1 /* 2 * linux/fs/ext4/inode.c 3 * 4 * Copyright (C) 1992, 1993, 1994, 1995 5 * Remy Card (card@masi.ibp.fr) 6 * Laboratoire MASI - Institut Blaise Pascal 7 * Universite Pierre et Marie Curie (Paris VI) 8 * 9 * from 10 * 11 * linux/fs/minix/inode.c 12 * 13 * Copyright (C) 1991, 1992 Linus Torvalds 14 * 15 * Goal-directed block allocation by Stephen Tweedie 16 * (sct@redhat.com), 1993, 1998 17 * Big-endian to little-endian byte-swapping/bitmaps by 18 * David S. Miller (davem@caip.rutgers.edu), 1995 19 * 64-bit file support on 64-bit platforms by Jakub Jelinek 20 * (jj@sunsite.ms.mff.cuni.cz) 21 * 22 * Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000 23 */ 24 25 #include <linux/module.h> 26 #include <linux/fs.h> 27 #include <linux/time.h> 28 #include <linux/jbd2.h> 29 #include <linux/highuid.h> 30 #include <linux/pagemap.h> 31 #include <linux/quotaops.h> 32 #include <linux/string.h> 33 #include <linux/buffer_head.h> 34 #include <linux/writeback.h> 35 #include <linux/pagevec.h> 36 #include <linux/mpage.h> 37 #include <linux/namei.h> 38 #include <linux/uio.h> 39 #include <linux/bio.h> 40 #include <linux/workqueue.h> 41 42 #include "ext4_jbd2.h" 43 #include "xattr.h" 44 #include "acl.h" 45 #include "ext4_extents.h" 46 47 #include <trace/events/ext4.h> 48 49 #define MPAGE_DA_EXTENT_TAIL 0x01 50 51 static inline int ext4_begin_ordered_truncate(struct inode *inode, 52 loff_t new_size) 53 { 54 return jbd2_journal_begin_ordered_truncate( 55 EXT4_SB(inode->i_sb)->s_journal, 56 &EXT4_I(inode)->jinode, 57 new_size); 58 } 59 60 static void ext4_invalidatepage(struct page *page, unsigned long offset); 61 62 /* 63 * Test whether an inode is a fast symlink. 64 */ 65 static int ext4_inode_is_fast_symlink(struct inode *inode) 66 { 67 int ea_blocks = EXT4_I(inode)->i_file_acl ? 68 (inode->i_sb->s_blocksize >> 9) : 0; 69 70 return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0); 71 } 72 73 /* 74 * Work out how many blocks we need to proceed with the next chunk of a 75 * truncate transaction. 76 */ 77 static unsigned long blocks_for_truncate(struct inode *inode) 78 { 79 ext4_lblk_t needed; 80 81 needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9); 82 83 /* Give ourselves just enough room to cope with inodes in which 84 * i_blocks is corrupt: we've seen disk corruptions in the past 85 * which resulted in random data in an inode which looked enough 86 * like a regular file for ext4 to try to delete it. Things 87 * will go a bit crazy if that happens, but at least we should 88 * try not to panic the whole kernel. */ 89 if (needed < 2) 90 needed = 2; 91 92 /* But we need to bound the transaction so we don't overflow the 93 * journal. */ 94 if (needed > EXT4_MAX_TRANS_DATA) 95 needed = EXT4_MAX_TRANS_DATA; 96 97 return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed; 98 } 99 100 /* 101 * Truncate transactions can be complex and absolutely huge. So we need to 102 * be able to restart the transaction at a conventient checkpoint to make 103 * sure we don't overflow the journal. 104 * 105 * start_transaction gets us a new handle for a truncate transaction, 106 * and extend_transaction tries to extend the existing one a bit. If 107 * extend fails, we need to propagate the failure up and restart the 108 * transaction in the top-level truncate loop. --sct 109 */ 110 static handle_t *start_transaction(struct inode *inode) 111 { 112 handle_t *result; 113 114 result = ext4_journal_start(inode, blocks_for_truncate(inode)); 115 if (!IS_ERR(result)) 116 return result; 117 118 ext4_std_error(inode->i_sb, PTR_ERR(result)); 119 return result; 120 } 121 122 /* 123 * Try to extend this transaction for the purposes of truncation. 124 * 125 * Returns 0 if we managed to create more room. If we can't create more 126 * room, and the transaction must be restarted we return 1. 127 */ 128 static int try_to_extend_transaction(handle_t *handle, struct inode *inode) 129 { 130 if (!ext4_handle_valid(handle)) 131 return 0; 132 if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1)) 133 return 0; 134 if (!ext4_journal_extend(handle, blocks_for_truncate(inode))) 135 return 0; 136 return 1; 137 } 138 139 /* 140 * Restart the transaction associated with *handle. This does a commit, 141 * so before we call here everything must be consistently dirtied against 142 * this transaction. 143 */ 144 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode, 145 int nblocks) 146 { 147 int ret; 148 149 /* 150 * Drop i_data_sem to avoid deadlock with ext4_get_blocks At this 151 * moment, get_block can be called only for blocks inside i_size since 152 * page cache has been already dropped and writes are blocked by 153 * i_mutex. So we can safely drop the i_data_sem here. 154 */ 155 BUG_ON(EXT4_JOURNAL(inode) == NULL); 156 jbd_debug(2, "restarting handle %p\n", handle); 157 up_write(&EXT4_I(inode)->i_data_sem); 158 ret = ext4_journal_restart(handle, blocks_for_truncate(inode)); 159 down_write(&EXT4_I(inode)->i_data_sem); 160 ext4_discard_preallocations(inode); 161 162 return ret; 163 } 164 165 /* 166 * Called at the last iput() if i_nlink is zero. 167 */ 168 void ext4_delete_inode(struct inode *inode) 169 { 170 handle_t *handle; 171 int err; 172 173 if (ext4_should_order_data(inode)) 174 ext4_begin_ordered_truncate(inode, 0); 175 truncate_inode_pages(&inode->i_data, 0); 176 177 if (is_bad_inode(inode)) 178 goto no_delete; 179 180 handle = ext4_journal_start(inode, blocks_for_truncate(inode)+3); 181 if (IS_ERR(handle)) { 182 ext4_std_error(inode->i_sb, PTR_ERR(handle)); 183 /* 184 * If we're going to skip the normal cleanup, we still need to 185 * make sure that the in-core orphan linked list is properly 186 * cleaned up. 187 */ 188 ext4_orphan_del(NULL, inode); 189 goto no_delete; 190 } 191 192 if (IS_SYNC(inode)) 193 ext4_handle_sync(handle); 194 inode->i_size = 0; 195 err = ext4_mark_inode_dirty(handle, inode); 196 if (err) { 197 ext4_warning(inode->i_sb, __func__, 198 "couldn't mark inode dirty (err %d)", err); 199 goto stop_handle; 200 } 201 if (inode->i_blocks) 202 ext4_truncate(inode); 203 204 /* 205 * ext4_ext_truncate() doesn't reserve any slop when it 206 * restarts journal transactions; therefore there may not be 207 * enough credits left in the handle to remove the inode from 208 * the orphan list and set the dtime field. 209 */ 210 if (!ext4_handle_has_enough_credits(handle, 3)) { 211 err = ext4_journal_extend(handle, 3); 212 if (err > 0) 213 err = ext4_journal_restart(handle, 3); 214 if (err != 0) { 215 ext4_warning(inode->i_sb, __func__, 216 "couldn't extend journal (err %d)", err); 217 stop_handle: 218 ext4_journal_stop(handle); 219 goto no_delete; 220 } 221 } 222 223 /* 224 * Kill off the orphan record which ext4_truncate created. 225 * AKPM: I think this can be inside the above `if'. 226 * Note that ext4_orphan_del() has to be able to cope with the 227 * deletion of a non-existent orphan - this is because we don't 228 * know if ext4_truncate() actually created an orphan record. 229 * (Well, we could do this if we need to, but heck - it works) 230 */ 231 ext4_orphan_del(handle, inode); 232 EXT4_I(inode)->i_dtime = get_seconds(); 233 234 /* 235 * One subtle ordering requirement: if anything has gone wrong 236 * (transaction abort, IO errors, whatever), then we can still 237 * do these next steps (the fs will already have been marked as 238 * having errors), but we can't free the inode if the mark_dirty 239 * fails. 240 */ 241 if (ext4_mark_inode_dirty(handle, inode)) 242 /* If that failed, just do the required in-core inode clear. */ 243 clear_inode(inode); 244 else 245 ext4_free_inode(handle, inode); 246 ext4_journal_stop(handle); 247 return; 248 no_delete: 249 clear_inode(inode); /* We must guarantee clearing of inode... */ 250 } 251 252 typedef struct { 253 __le32 *p; 254 __le32 key; 255 struct buffer_head *bh; 256 } Indirect; 257 258 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v) 259 { 260 p->key = *(p->p = v); 261 p->bh = bh; 262 } 263 264 /** 265 * ext4_block_to_path - parse the block number into array of offsets 266 * @inode: inode in question (we are only interested in its superblock) 267 * @i_block: block number to be parsed 268 * @offsets: array to store the offsets in 269 * @boundary: set this non-zero if the referred-to block is likely to be 270 * followed (on disk) by an indirect block. 271 * 272 * To store the locations of file's data ext4 uses a data structure common 273 * for UNIX filesystems - tree of pointers anchored in the inode, with 274 * data blocks at leaves and indirect blocks in intermediate nodes. 275 * This function translates the block number into path in that tree - 276 * return value is the path length and @offsets[n] is the offset of 277 * pointer to (n+1)th node in the nth one. If @block is out of range 278 * (negative or too large) warning is printed and zero returned. 279 * 280 * Note: function doesn't find node addresses, so no IO is needed. All 281 * we need to know is the capacity of indirect blocks (taken from the 282 * inode->i_sb). 283 */ 284 285 /* 286 * Portability note: the last comparison (check that we fit into triple 287 * indirect block) is spelled differently, because otherwise on an 288 * architecture with 32-bit longs and 8Kb pages we might get into trouble 289 * if our filesystem had 8Kb blocks. We might use long long, but that would 290 * kill us on x86. Oh, well, at least the sign propagation does not matter - 291 * i_block would have to be negative in the very beginning, so we would not 292 * get there at all. 293 */ 294 295 static int ext4_block_to_path(struct inode *inode, 296 ext4_lblk_t i_block, 297 ext4_lblk_t offsets[4], int *boundary) 298 { 299 int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb); 300 int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb); 301 const long direct_blocks = EXT4_NDIR_BLOCKS, 302 indirect_blocks = ptrs, 303 double_blocks = (1 << (ptrs_bits * 2)); 304 int n = 0; 305 int final = 0; 306 307 if (i_block < direct_blocks) { 308 offsets[n++] = i_block; 309 final = direct_blocks; 310 } else if ((i_block -= direct_blocks) < indirect_blocks) { 311 offsets[n++] = EXT4_IND_BLOCK; 312 offsets[n++] = i_block; 313 final = ptrs; 314 } else if ((i_block -= indirect_blocks) < double_blocks) { 315 offsets[n++] = EXT4_DIND_BLOCK; 316 offsets[n++] = i_block >> ptrs_bits; 317 offsets[n++] = i_block & (ptrs - 1); 318 final = ptrs; 319 } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) { 320 offsets[n++] = EXT4_TIND_BLOCK; 321 offsets[n++] = i_block >> (ptrs_bits * 2); 322 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1); 323 offsets[n++] = i_block & (ptrs - 1); 324 final = ptrs; 325 } else { 326 ext4_warning(inode->i_sb, "ext4_block_to_path", 327 "block %lu > max in inode %lu", 328 i_block + direct_blocks + 329 indirect_blocks + double_blocks, inode->i_ino); 330 } 331 if (boundary) 332 *boundary = final - 1 - (i_block & (ptrs - 1)); 333 return n; 334 } 335 336 static int __ext4_check_blockref(const char *function, struct inode *inode, 337 __le32 *p, unsigned int max) 338 { 339 __le32 *bref = p; 340 unsigned int blk; 341 342 while (bref < p+max) { 343 blk = le32_to_cpu(*bref++); 344 if (blk && 345 unlikely(!ext4_data_block_valid(EXT4_SB(inode->i_sb), 346 blk, 1))) { 347 ext4_error(inode->i_sb, function, 348 "invalid block reference %u " 349 "in inode #%lu", blk, inode->i_ino); 350 return -EIO; 351 } 352 } 353 return 0; 354 } 355 356 357 #define ext4_check_indirect_blockref(inode, bh) \ 358 __ext4_check_blockref(__func__, inode, (__le32 *)(bh)->b_data, \ 359 EXT4_ADDR_PER_BLOCK((inode)->i_sb)) 360 361 #define ext4_check_inode_blockref(inode) \ 362 __ext4_check_blockref(__func__, inode, EXT4_I(inode)->i_data, \ 363 EXT4_NDIR_BLOCKS) 364 365 /** 366 * ext4_get_branch - read the chain of indirect blocks leading to data 367 * @inode: inode in question 368 * @depth: depth of the chain (1 - direct pointer, etc.) 369 * @offsets: offsets of pointers in inode/indirect blocks 370 * @chain: place to store the result 371 * @err: here we store the error value 372 * 373 * Function fills the array of triples <key, p, bh> and returns %NULL 374 * if everything went OK or the pointer to the last filled triple 375 * (incomplete one) otherwise. Upon the return chain[i].key contains 376 * the number of (i+1)-th block in the chain (as it is stored in memory, 377 * i.e. little-endian 32-bit), chain[i].p contains the address of that 378 * number (it points into struct inode for i==0 and into the bh->b_data 379 * for i>0) and chain[i].bh points to the buffer_head of i-th indirect 380 * block for i>0 and NULL for i==0. In other words, it holds the block 381 * numbers of the chain, addresses they were taken from (and where we can 382 * verify that chain did not change) and buffer_heads hosting these 383 * numbers. 384 * 385 * Function stops when it stumbles upon zero pointer (absent block) 386 * (pointer to last triple returned, *@err == 0) 387 * or when it gets an IO error reading an indirect block 388 * (ditto, *@err == -EIO) 389 * or when it reads all @depth-1 indirect blocks successfully and finds 390 * the whole chain, all way to the data (returns %NULL, *err == 0). 391 * 392 * Need to be called with 393 * down_read(&EXT4_I(inode)->i_data_sem) 394 */ 395 static Indirect *ext4_get_branch(struct inode *inode, int depth, 396 ext4_lblk_t *offsets, 397 Indirect chain[4], int *err) 398 { 399 struct super_block *sb = inode->i_sb; 400 Indirect *p = chain; 401 struct buffer_head *bh; 402 403 *err = 0; 404 /* i_data is not going away, no lock needed */ 405 add_chain(chain, NULL, EXT4_I(inode)->i_data + *offsets); 406 if (!p->key) 407 goto no_block; 408 while (--depth) { 409 bh = sb_getblk(sb, le32_to_cpu(p->key)); 410 if (unlikely(!bh)) 411 goto failure; 412 413 if (!bh_uptodate_or_lock(bh)) { 414 if (bh_submit_read(bh) < 0) { 415 put_bh(bh); 416 goto failure; 417 } 418 /* validate block references */ 419 if (ext4_check_indirect_blockref(inode, bh)) { 420 put_bh(bh); 421 goto failure; 422 } 423 } 424 425 add_chain(++p, bh, (__le32 *)bh->b_data + *++offsets); 426 /* Reader: end */ 427 if (!p->key) 428 goto no_block; 429 } 430 return NULL; 431 432 failure: 433 *err = -EIO; 434 no_block: 435 return p; 436 } 437 438 /** 439 * ext4_find_near - find a place for allocation with sufficient locality 440 * @inode: owner 441 * @ind: descriptor of indirect block. 442 * 443 * This function returns the preferred place for block allocation. 444 * It is used when heuristic for sequential allocation fails. 445 * Rules are: 446 * + if there is a block to the left of our position - allocate near it. 447 * + if pointer will live in indirect block - allocate near that block. 448 * + if pointer will live in inode - allocate in the same 449 * cylinder group. 450 * 451 * In the latter case we colour the starting block by the callers PID to 452 * prevent it from clashing with concurrent allocations for a different inode 453 * in the same block group. The PID is used here so that functionally related 454 * files will be close-by on-disk. 455 * 456 * Caller must make sure that @ind is valid and will stay that way. 457 */ 458 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind) 459 { 460 struct ext4_inode_info *ei = EXT4_I(inode); 461 __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data; 462 __le32 *p; 463 ext4_fsblk_t bg_start; 464 ext4_fsblk_t last_block; 465 ext4_grpblk_t colour; 466 ext4_group_t block_group; 467 int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb)); 468 469 /* Try to find previous block */ 470 for (p = ind->p - 1; p >= start; p--) { 471 if (*p) 472 return le32_to_cpu(*p); 473 } 474 475 /* No such thing, so let's try location of indirect block */ 476 if (ind->bh) 477 return ind->bh->b_blocknr; 478 479 /* 480 * It is going to be referred to from the inode itself? OK, just put it 481 * into the same cylinder group then. 482 */ 483 block_group = ei->i_block_group; 484 if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) { 485 block_group &= ~(flex_size-1); 486 if (S_ISREG(inode->i_mode)) 487 block_group++; 488 } 489 bg_start = ext4_group_first_block_no(inode->i_sb, block_group); 490 last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1; 491 492 /* 493 * If we are doing delayed allocation, we don't need take 494 * colour into account. 495 */ 496 if (test_opt(inode->i_sb, DELALLOC)) 497 return bg_start; 498 499 if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block) 500 colour = (current->pid % 16) * 501 (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16); 502 else 503 colour = (current->pid % 16) * ((last_block - bg_start) / 16); 504 return bg_start + colour; 505 } 506 507 /** 508 * ext4_find_goal - find a preferred place for allocation. 509 * @inode: owner 510 * @block: block we want 511 * @partial: pointer to the last triple within a chain 512 * 513 * Normally this function find the preferred place for block allocation, 514 * returns it. 515 * Because this is only used for non-extent files, we limit the block nr 516 * to 32 bits. 517 */ 518 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block, 519 Indirect *partial) 520 { 521 ext4_fsblk_t goal; 522 523 /* 524 * XXX need to get goal block from mballoc's data structures 525 */ 526 527 goal = ext4_find_near(inode, partial); 528 goal = goal & EXT4_MAX_BLOCK_FILE_PHYS; 529 return goal; 530 } 531 532 /** 533 * ext4_blks_to_allocate: Look up the block map and count the number 534 * of direct blocks need to be allocated for the given branch. 535 * 536 * @branch: chain of indirect blocks 537 * @k: number of blocks need for indirect blocks 538 * @blks: number of data blocks to be mapped. 539 * @blocks_to_boundary: the offset in the indirect block 540 * 541 * return the total number of blocks to be allocate, including the 542 * direct and indirect blocks. 543 */ 544 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned int blks, 545 int blocks_to_boundary) 546 { 547 unsigned int count = 0; 548 549 /* 550 * Simple case, [t,d]Indirect block(s) has not allocated yet 551 * then it's clear blocks on that path have not allocated 552 */ 553 if (k > 0) { 554 /* right now we don't handle cross boundary allocation */ 555 if (blks < blocks_to_boundary + 1) 556 count += blks; 557 else 558 count += blocks_to_boundary + 1; 559 return count; 560 } 561 562 count++; 563 while (count < blks && count <= blocks_to_boundary && 564 le32_to_cpu(*(branch[0].p + count)) == 0) { 565 count++; 566 } 567 return count; 568 } 569 570 /** 571 * ext4_alloc_blocks: multiple allocate blocks needed for a branch 572 * @indirect_blks: the number of blocks need to allocate for indirect 573 * blocks 574 * 575 * @new_blocks: on return it will store the new block numbers for 576 * the indirect blocks(if needed) and the first direct block, 577 * @blks: on return it will store the total number of allocated 578 * direct blocks 579 */ 580 static int ext4_alloc_blocks(handle_t *handle, struct inode *inode, 581 ext4_lblk_t iblock, ext4_fsblk_t goal, 582 int indirect_blks, int blks, 583 ext4_fsblk_t new_blocks[4], int *err) 584 { 585 struct ext4_allocation_request ar; 586 int target, i; 587 unsigned long count = 0, blk_allocated = 0; 588 int index = 0; 589 ext4_fsblk_t current_block = 0; 590 int ret = 0; 591 592 /* 593 * Here we try to allocate the requested multiple blocks at once, 594 * on a best-effort basis. 595 * To build a branch, we should allocate blocks for 596 * the indirect blocks(if not allocated yet), and at least 597 * the first direct block of this branch. That's the 598 * minimum number of blocks need to allocate(required) 599 */ 600 /* first we try to allocate the indirect blocks */ 601 target = indirect_blks; 602 while (target > 0) { 603 count = target; 604 /* allocating blocks for indirect blocks and direct blocks */ 605 current_block = ext4_new_meta_blocks(handle, inode, 606 goal, &count, err); 607 if (*err) 608 goto failed_out; 609 610 BUG_ON(current_block + count > EXT4_MAX_BLOCK_FILE_PHYS); 611 612 target -= count; 613 /* allocate blocks for indirect blocks */ 614 while (index < indirect_blks && count) { 615 new_blocks[index++] = current_block++; 616 count--; 617 } 618 if (count > 0) { 619 /* 620 * save the new block number 621 * for the first direct block 622 */ 623 new_blocks[index] = current_block; 624 printk(KERN_INFO "%s returned more blocks than " 625 "requested\n", __func__); 626 WARN_ON(1); 627 break; 628 } 629 } 630 631 target = blks - count ; 632 blk_allocated = count; 633 if (!target) 634 goto allocated; 635 /* Now allocate data blocks */ 636 memset(&ar, 0, sizeof(ar)); 637 ar.inode = inode; 638 ar.goal = goal; 639 ar.len = target; 640 ar.logical = iblock; 641 if (S_ISREG(inode->i_mode)) 642 /* enable in-core preallocation only for regular files */ 643 ar.flags = EXT4_MB_HINT_DATA; 644 645 current_block = ext4_mb_new_blocks(handle, &ar, err); 646 BUG_ON(current_block + ar.len > EXT4_MAX_BLOCK_FILE_PHYS); 647 648 if (*err && (target == blks)) { 649 /* 650 * if the allocation failed and we didn't allocate 651 * any blocks before 652 */ 653 goto failed_out; 654 } 655 if (!*err) { 656 if (target == blks) { 657 /* 658 * save the new block number 659 * for the first direct block 660 */ 661 new_blocks[index] = current_block; 662 } 663 blk_allocated += ar.len; 664 } 665 allocated: 666 /* total number of blocks allocated for direct blocks */ 667 ret = blk_allocated; 668 *err = 0; 669 return ret; 670 failed_out: 671 for (i = 0; i < index; i++) 672 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 0); 673 return ret; 674 } 675 676 /** 677 * ext4_alloc_branch - allocate and set up a chain of blocks. 678 * @inode: owner 679 * @indirect_blks: number of allocated indirect blocks 680 * @blks: number of allocated direct blocks 681 * @offsets: offsets (in the blocks) to store the pointers to next. 682 * @branch: place to store the chain in. 683 * 684 * This function allocates blocks, zeroes out all but the last one, 685 * links them into chain and (if we are synchronous) writes them to disk. 686 * In other words, it prepares a branch that can be spliced onto the 687 * inode. It stores the information about that chain in the branch[], in 688 * the same format as ext4_get_branch() would do. We are calling it after 689 * we had read the existing part of chain and partial points to the last 690 * triple of that (one with zero ->key). Upon the exit we have the same 691 * picture as after the successful ext4_get_block(), except that in one 692 * place chain is disconnected - *branch->p is still zero (we did not 693 * set the last link), but branch->key contains the number that should 694 * be placed into *branch->p to fill that gap. 695 * 696 * If allocation fails we free all blocks we've allocated (and forget 697 * their buffer_heads) and return the error value the from failed 698 * ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain 699 * as described above and return 0. 700 */ 701 static int ext4_alloc_branch(handle_t *handle, struct inode *inode, 702 ext4_lblk_t iblock, int indirect_blks, 703 int *blks, ext4_fsblk_t goal, 704 ext4_lblk_t *offsets, Indirect *branch) 705 { 706 int blocksize = inode->i_sb->s_blocksize; 707 int i, n = 0; 708 int err = 0; 709 struct buffer_head *bh; 710 int num; 711 ext4_fsblk_t new_blocks[4]; 712 ext4_fsblk_t current_block; 713 714 num = ext4_alloc_blocks(handle, inode, iblock, goal, indirect_blks, 715 *blks, new_blocks, &err); 716 if (err) 717 return err; 718 719 branch[0].key = cpu_to_le32(new_blocks[0]); 720 /* 721 * metadata blocks and data blocks are allocated. 722 */ 723 for (n = 1; n <= indirect_blks; n++) { 724 /* 725 * Get buffer_head for parent block, zero it out 726 * and set the pointer to new one, then send 727 * parent to disk. 728 */ 729 bh = sb_getblk(inode->i_sb, new_blocks[n-1]); 730 branch[n].bh = bh; 731 lock_buffer(bh); 732 BUFFER_TRACE(bh, "call get_create_access"); 733 err = ext4_journal_get_create_access(handle, bh); 734 if (err) { 735 /* Don't brelse(bh) here; it's done in 736 * ext4_journal_forget() below */ 737 unlock_buffer(bh); 738 goto failed; 739 } 740 741 memset(bh->b_data, 0, blocksize); 742 branch[n].p = (__le32 *) bh->b_data + offsets[n]; 743 branch[n].key = cpu_to_le32(new_blocks[n]); 744 *branch[n].p = branch[n].key; 745 if (n == indirect_blks) { 746 current_block = new_blocks[n]; 747 /* 748 * End of chain, update the last new metablock of 749 * the chain to point to the new allocated 750 * data blocks numbers 751 */ 752 for (i = 1; i < num; i++) 753 *(branch[n].p + i) = cpu_to_le32(++current_block); 754 } 755 BUFFER_TRACE(bh, "marking uptodate"); 756 set_buffer_uptodate(bh); 757 unlock_buffer(bh); 758 759 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata"); 760 err = ext4_handle_dirty_metadata(handle, inode, bh); 761 if (err) 762 goto failed; 763 } 764 *blks = num; 765 return err; 766 failed: 767 /* Allocation failed, free what we already allocated */ 768 ext4_free_blocks(handle, inode, 0, new_blocks[0], 1, 0); 769 for (i = 1; i <= n ; i++) { 770 /* 771 * branch[i].bh is newly allocated, so there is no 772 * need to revoke the block, which is why we don't 773 * need to set EXT4_FREE_BLOCKS_METADATA. 774 */ 775 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 776 EXT4_FREE_BLOCKS_FORGET); 777 } 778 for (i = n+1; i < indirect_blks; i++) 779 ext4_free_blocks(handle, inode, 0, new_blocks[i], 1, 0); 780 781 ext4_free_blocks(handle, inode, 0, new_blocks[i], num, 0); 782 783 return err; 784 } 785 786 /** 787 * ext4_splice_branch - splice the allocated branch onto inode. 788 * @inode: owner 789 * @block: (logical) number of block we are adding 790 * @chain: chain of indirect blocks (with a missing link - see 791 * ext4_alloc_branch) 792 * @where: location of missing link 793 * @num: number of indirect blocks we are adding 794 * @blks: number of direct blocks we are adding 795 * 796 * This function fills the missing link and does all housekeeping needed in 797 * inode (->i_blocks, etc.). In case of success we end up with the full 798 * chain to new block and return 0. 799 */ 800 static int ext4_splice_branch(handle_t *handle, struct inode *inode, 801 ext4_lblk_t block, Indirect *where, int num, 802 int blks) 803 { 804 int i; 805 int err = 0; 806 ext4_fsblk_t current_block; 807 808 /* 809 * If we're splicing into a [td]indirect block (as opposed to the 810 * inode) then we need to get write access to the [td]indirect block 811 * before the splice. 812 */ 813 if (where->bh) { 814 BUFFER_TRACE(where->bh, "get_write_access"); 815 err = ext4_journal_get_write_access(handle, where->bh); 816 if (err) 817 goto err_out; 818 } 819 /* That's it */ 820 821 *where->p = where->key; 822 823 /* 824 * Update the host buffer_head or inode to point to more just allocated 825 * direct blocks blocks 826 */ 827 if (num == 0 && blks > 1) { 828 current_block = le32_to_cpu(where->key) + 1; 829 for (i = 1; i < blks; i++) 830 *(where->p + i) = cpu_to_le32(current_block++); 831 } 832 833 /* We are done with atomic stuff, now do the rest of housekeeping */ 834 /* had we spliced it onto indirect block? */ 835 if (where->bh) { 836 /* 837 * If we spliced it onto an indirect block, we haven't 838 * altered the inode. Note however that if it is being spliced 839 * onto an indirect block at the very end of the file (the 840 * file is growing) then we *will* alter the inode to reflect 841 * the new i_size. But that is not done here - it is done in 842 * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode. 843 */ 844 jbd_debug(5, "splicing indirect only\n"); 845 BUFFER_TRACE(where->bh, "call ext4_handle_dirty_metadata"); 846 err = ext4_handle_dirty_metadata(handle, inode, where->bh); 847 if (err) 848 goto err_out; 849 } else { 850 /* 851 * OK, we spliced it into the inode itself on a direct block. 852 */ 853 ext4_mark_inode_dirty(handle, inode); 854 jbd_debug(5, "splicing direct\n"); 855 } 856 return err; 857 858 err_out: 859 for (i = 1; i <= num; i++) { 860 /* 861 * branch[i].bh is newly allocated, so there is no 862 * need to revoke the block, which is why we don't 863 * need to set EXT4_FREE_BLOCKS_METADATA. 864 */ 865 ext4_free_blocks(handle, inode, where[i].bh, 0, 1, 866 EXT4_FREE_BLOCKS_FORGET); 867 } 868 ext4_free_blocks(handle, inode, 0, le32_to_cpu(where[num].key), 869 blks, 0); 870 871 return err; 872 } 873 874 /* 875 * The ext4_ind_get_blocks() function handles non-extents inodes 876 * (i.e., using the traditional indirect/double-indirect i_blocks 877 * scheme) for ext4_get_blocks(). 878 * 879 * Allocation strategy is simple: if we have to allocate something, we will 880 * have to go the whole way to leaf. So let's do it before attaching anything 881 * to tree, set linkage between the newborn blocks, write them if sync is 882 * required, recheck the path, free and repeat if check fails, otherwise 883 * set the last missing link (that will protect us from any truncate-generated 884 * removals - all blocks on the path are immune now) and possibly force the 885 * write on the parent block. 886 * That has a nice additional property: no special recovery from the failed 887 * allocations is needed - we simply release blocks and do not touch anything 888 * reachable from inode. 889 * 890 * `handle' can be NULL if create == 0. 891 * 892 * return > 0, # of blocks mapped or allocated. 893 * return = 0, if plain lookup failed. 894 * return < 0, error case. 895 * 896 * The ext4_ind_get_blocks() function should be called with 897 * down_write(&EXT4_I(inode)->i_data_sem) if allocating filesystem 898 * blocks (i.e., flags has EXT4_GET_BLOCKS_CREATE set) or 899 * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system 900 * blocks. 901 */ 902 static int ext4_ind_get_blocks(handle_t *handle, struct inode *inode, 903 ext4_lblk_t iblock, unsigned int maxblocks, 904 struct buffer_head *bh_result, 905 int flags) 906 { 907 int err = -EIO; 908 ext4_lblk_t offsets[4]; 909 Indirect chain[4]; 910 Indirect *partial; 911 ext4_fsblk_t goal; 912 int indirect_blks; 913 int blocks_to_boundary = 0; 914 int depth; 915 int count = 0; 916 ext4_fsblk_t first_block = 0; 917 918 J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)); 919 J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0); 920 depth = ext4_block_to_path(inode, iblock, offsets, 921 &blocks_to_boundary); 922 923 if (depth == 0) 924 goto out; 925 926 partial = ext4_get_branch(inode, depth, offsets, chain, &err); 927 928 /* Simplest case - block found, no allocation needed */ 929 if (!partial) { 930 first_block = le32_to_cpu(chain[depth - 1].key); 931 clear_buffer_new(bh_result); 932 count++; 933 /*map more blocks*/ 934 while (count < maxblocks && count <= blocks_to_boundary) { 935 ext4_fsblk_t blk; 936 937 blk = le32_to_cpu(*(chain[depth-1].p + count)); 938 939 if (blk == first_block + count) 940 count++; 941 else 942 break; 943 } 944 goto got_it; 945 } 946 947 /* Next simple case - plain lookup or failed read of indirect block */ 948 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0 || err == -EIO) 949 goto cleanup; 950 951 /* 952 * Okay, we need to do block allocation. 953 */ 954 goal = ext4_find_goal(inode, iblock, partial); 955 956 /* the number of blocks need to allocate for [d,t]indirect blocks */ 957 indirect_blks = (chain + depth) - partial - 1; 958 959 /* 960 * Next look up the indirect map to count the totoal number of 961 * direct blocks to allocate for this branch. 962 */ 963 count = ext4_blks_to_allocate(partial, indirect_blks, 964 maxblocks, blocks_to_boundary); 965 /* 966 * Block out ext4_truncate while we alter the tree 967 */ 968 err = ext4_alloc_branch(handle, inode, iblock, indirect_blks, 969 &count, goal, 970 offsets + (partial - chain), partial); 971 972 /* 973 * The ext4_splice_branch call will free and forget any buffers 974 * on the new chain if there is a failure, but that risks using 975 * up transaction credits, especially for bitmaps where the 976 * credits cannot be returned. Can we handle this somehow? We 977 * may need to return -EAGAIN upwards in the worst case. --sct 978 */ 979 if (!err) 980 err = ext4_splice_branch(handle, inode, iblock, 981 partial, indirect_blks, count); 982 if (err) 983 goto cleanup; 984 985 set_buffer_new(bh_result); 986 987 ext4_update_inode_fsync_trans(handle, inode, 1); 988 got_it: 989 map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key)); 990 if (count > blocks_to_boundary) 991 set_buffer_boundary(bh_result); 992 err = count; 993 /* Clean up and exit */ 994 partial = chain + depth - 1; /* the whole chain */ 995 cleanup: 996 while (partial > chain) { 997 BUFFER_TRACE(partial->bh, "call brelse"); 998 brelse(partial->bh); 999 partial--; 1000 } 1001 BUFFER_TRACE(bh_result, "returned"); 1002 out: 1003 return err; 1004 } 1005 1006 #ifdef CONFIG_QUOTA 1007 qsize_t *ext4_get_reserved_space(struct inode *inode) 1008 { 1009 return &EXT4_I(inode)->i_reserved_quota; 1010 } 1011 #endif 1012 /* 1013 * Calculate the number of metadata blocks need to reserve 1014 * to allocate @blocks for non extent file based file 1015 */ 1016 static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks) 1017 { 1018 int icap = EXT4_ADDR_PER_BLOCK(inode->i_sb); 1019 int ind_blks, dind_blks, tind_blks; 1020 1021 /* number of new indirect blocks needed */ 1022 ind_blks = (blocks + icap - 1) / icap; 1023 1024 dind_blks = (ind_blks + icap - 1) / icap; 1025 1026 tind_blks = 1; 1027 1028 return ind_blks + dind_blks + tind_blks; 1029 } 1030 1031 /* 1032 * Calculate the number of metadata blocks need to reserve 1033 * to allocate given number of blocks 1034 */ 1035 static int ext4_calc_metadata_amount(struct inode *inode, int blocks) 1036 { 1037 if (!blocks) 1038 return 0; 1039 1040 if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) 1041 return ext4_ext_calc_metadata_amount(inode, blocks); 1042 1043 return ext4_indirect_calc_metadata_amount(inode, blocks); 1044 } 1045 1046 static void ext4_da_update_reserve_space(struct inode *inode, int used) 1047 { 1048 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 1049 int total, mdb, mdb_free, mdb_claim = 0; 1050 1051 spin_lock(&EXT4_I(inode)->i_block_reservation_lock); 1052 /* recalculate the number of metablocks still need to be reserved */ 1053 total = EXT4_I(inode)->i_reserved_data_blocks - used; 1054 mdb = ext4_calc_metadata_amount(inode, total); 1055 1056 /* figure out how many metablocks to release */ 1057 BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks); 1058 mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb; 1059 1060 if (mdb_free) { 1061 /* Account for allocated meta_blocks */ 1062 mdb_claim = EXT4_I(inode)->i_allocated_meta_blocks; 1063 BUG_ON(mdb_free < mdb_claim); 1064 mdb_free -= mdb_claim; 1065 1066 /* update fs dirty blocks counter */ 1067 percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free); 1068 EXT4_I(inode)->i_allocated_meta_blocks = 0; 1069 EXT4_I(inode)->i_reserved_meta_blocks = mdb; 1070 } 1071 1072 /* update per-inode reservations */ 1073 BUG_ON(used > EXT4_I(inode)->i_reserved_data_blocks); 1074 EXT4_I(inode)->i_reserved_data_blocks -= used; 1075 percpu_counter_sub(&sbi->s_dirtyblocks_counter, used + mdb_claim); 1076 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 1077 1078 vfs_dq_claim_block(inode, used + mdb_claim); 1079 1080 /* 1081 * free those over-booking quota for metadata blocks 1082 */ 1083 if (mdb_free) 1084 vfs_dq_release_reservation_block(inode, mdb_free); 1085 1086 /* 1087 * If we have done all the pending block allocations and if 1088 * there aren't any writers on the inode, we can discard the 1089 * inode's preallocations. 1090 */ 1091 if (!total && (atomic_read(&inode->i_writecount) == 0)) 1092 ext4_discard_preallocations(inode); 1093 } 1094 1095 static int check_block_validity(struct inode *inode, const char *msg, 1096 sector_t logical, sector_t phys, int len) 1097 { 1098 if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), phys, len)) { 1099 ext4_error(inode->i_sb, msg, 1100 "inode #%lu logical block %llu mapped to %llu " 1101 "(size %d)", inode->i_ino, 1102 (unsigned long long) logical, 1103 (unsigned long long) phys, len); 1104 return -EIO; 1105 } 1106 return 0; 1107 } 1108 1109 /* 1110 * Return the number of contiguous dirty pages in a given inode 1111 * starting at page frame idx. 1112 */ 1113 static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx, 1114 unsigned int max_pages) 1115 { 1116 struct address_space *mapping = inode->i_mapping; 1117 pgoff_t index; 1118 struct pagevec pvec; 1119 pgoff_t num = 0; 1120 int i, nr_pages, done = 0; 1121 1122 if (max_pages == 0) 1123 return 0; 1124 pagevec_init(&pvec, 0); 1125 while (!done) { 1126 index = idx; 1127 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, 1128 PAGECACHE_TAG_DIRTY, 1129 (pgoff_t)PAGEVEC_SIZE); 1130 if (nr_pages == 0) 1131 break; 1132 for (i = 0; i < nr_pages; i++) { 1133 struct page *page = pvec.pages[i]; 1134 struct buffer_head *bh, *head; 1135 1136 lock_page(page); 1137 if (unlikely(page->mapping != mapping) || 1138 !PageDirty(page) || 1139 PageWriteback(page) || 1140 page->index != idx) { 1141 done = 1; 1142 unlock_page(page); 1143 break; 1144 } 1145 if (page_has_buffers(page)) { 1146 bh = head = page_buffers(page); 1147 do { 1148 if (!buffer_delay(bh) && 1149 !buffer_unwritten(bh)) 1150 done = 1; 1151 bh = bh->b_this_page; 1152 } while (!done && (bh != head)); 1153 } 1154 unlock_page(page); 1155 if (done) 1156 break; 1157 idx++; 1158 num++; 1159 if (num >= max_pages) 1160 break; 1161 } 1162 pagevec_release(&pvec); 1163 } 1164 return num; 1165 } 1166 1167 /* 1168 * The ext4_get_blocks() function tries to look up the requested blocks, 1169 * and returns if the blocks are already mapped. 1170 * 1171 * Otherwise it takes the write lock of the i_data_sem and allocate blocks 1172 * and store the allocated blocks in the result buffer head and mark it 1173 * mapped. 1174 * 1175 * If file type is extents based, it will call ext4_ext_get_blocks(), 1176 * Otherwise, call with ext4_ind_get_blocks() to handle indirect mapping 1177 * based files 1178 * 1179 * On success, it returns the number of blocks being mapped or allocate. 1180 * if create==0 and the blocks are pre-allocated and uninitialized block, 1181 * the result buffer head is unmapped. If the create ==1, it will make sure 1182 * the buffer head is mapped. 1183 * 1184 * It returns 0 if plain look up failed (blocks have not been allocated), in 1185 * that casem, buffer head is unmapped 1186 * 1187 * It returns the error in case of allocation failure. 1188 */ 1189 int ext4_get_blocks(handle_t *handle, struct inode *inode, sector_t block, 1190 unsigned int max_blocks, struct buffer_head *bh, 1191 int flags) 1192 { 1193 int retval; 1194 1195 clear_buffer_mapped(bh); 1196 clear_buffer_unwritten(bh); 1197 1198 ext_debug("ext4_get_blocks(): inode %lu, flag %d, max_blocks %u," 1199 "logical block %lu\n", inode->i_ino, flags, max_blocks, 1200 (unsigned long)block); 1201 /* 1202 * Try to see if we can get the block without requesting a new 1203 * file system block. 1204 */ 1205 down_read((&EXT4_I(inode)->i_data_sem)); 1206 if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) { 1207 retval = ext4_ext_get_blocks(handle, inode, block, max_blocks, 1208 bh, 0); 1209 } else { 1210 retval = ext4_ind_get_blocks(handle, inode, block, max_blocks, 1211 bh, 0); 1212 } 1213 up_read((&EXT4_I(inode)->i_data_sem)); 1214 1215 if (retval > 0 && buffer_mapped(bh)) { 1216 int ret = check_block_validity(inode, "file system corruption", 1217 block, bh->b_blocknr, retval); 1218 if (ret != 0) 1219 return ret; 1220 } 1221 1222 /* If it is only a block(s) look up */ 1223 if ((flags & EXT4_GET_BLOCKS_CREATE) == 0) 1224 return retval; 1225 1226 /* 1227 * Returns if the blocks have already allocated 1228 * 1229 * Note that if blocks have been preallocated 1230 * ext4_ext_get_block() returns th create = 0 1231 * with buffer head unmapped. 1232 */ 1233 if (retval > 0 && buffer_mapped(bh)) 1234 return retval; 1235 1236 /* 1237 * When we call get_blocks without the create flag, the 1238 * BH_Unwritten flag could have gotten set if the blocks 1239 * requested were part of a uninitialized extent. We need to 1240 * clear this flag now that we are committed to convert all or 1241 * part of the uninitialized extent to be an initialized 1242 * extent. This is because we need to avoid the combination 1243 * of BH_Unwritten and BH_Mapped flags being simultaneously 1244 * set on the buffer_head. 1245 */ 1246 clear_buffer_unwritten(bh); 1247 1248 /* 1249 * New blocks allocate and/or writing to uninitialized extent 1250 * will possibly result in updating i_data, so we take 1251 * the write lock of i_data_sem, and call get_blocks() 1252 * with create == 1 flag. 1253 */ 1254 down_write((&EXT4_I(inode)->i_data_sem)); 1255 1256 /* 1257 * if the caller is from delayed allocation writeout path 1258 * we have already reserved fs blocks for allocation 1259 * let the underlying get_block() function know to 1260 * avoid double accounting 1261 */ 1262 if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) 1263 EXT4_I(inode)->i_delalloc_reserved_flag = 1; 1264 /* 1265 * We need to check for EXT4 here because migrate 1266 * could have changed the inode type in between 1267 */ 1268 if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) { 1269 retval = ext4_ext_get_blocks(handle, inode, block, max_blocks, 1270 bh, flags); 1271 } else { 1272 retval = ext4_ind_get_blocks(handle, inode, block, 1273 max_blocks, bh, flags); 1274 1275 if (retval > 0 && buffer_new(bh)) { 1276 /* 1277 * We allocated new blocks which will result in 1278 * i_data's format changing. Force the migrate 1279 * to fail by clearing migrate flags 1280 */ 1281 EXT4_I(inode)->i_state &= ~EXT4_STATE_EXT_MIGRATE; 1282 } 1283 } 1284 1285 if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) 1286 EXT4_I(inode)->i_delalloc_reserved_flag = 0; 1287 1288 /* 1289 * Update reserved blocks/metadata blocks after successful 1290 * block allocation which had been deferred till now. 1291 */ 1292 if ((retval > 0) && (flags & EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE)) 1293 ext4_da_update_reserve_space(inode, retval); 1294 1295 up_write((&EXT4_I(inode)->i_data_sem)); 1296 if (retval > 0 && buffer_mapped(bh)) { 1297 int ret = check_block_validity(inode, "file system " 1298 "corruption after allocation", 1299 block, bh->b_blocknr, retval); 1300 if (ret != 0) 1301 return ret; 1302 } 1303 return retval; 1304 } 1305 1306 /* Maximum number of blocks we map for direct IO at once. */ 1307 #define DIO_MAX_BLOCKS 4096 1308 1309 int ext4_get_block(struct inode *inode, sector_t iblock, 1310 struct buffer_head *bh_result, int create) 1311 { 1312 handle_t *handle = ext4_journal_current_handle(); 1313 int ret = 0, started = 0; 1314 unsigned max_blocks = bh_result->b_size >> inode->i_blkbits; 1315 int dio_credits; 1316 1317 if (create && !handle) { 1318 /* Direct IO write... */ 1319 if (max_blocks > DIO_MAX_BLOCKS) 1320 max_blocks = DIO_MAX_BLOCKS; 1321 dio_credits = ext4_chunk_trans_blocks(inode, max_blocks); 1322 handle = ext4_journal_start(inode, dio_credits); 1323 if (IS_ERR(handle)) { 1324 ret = PTR_ERR(handle); 1325 goto out; 1326 } 1327 started = 1; 1328 } 1329 1330 ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result, 1331 create ? EXT4_GET_BLOCKS_CREATE : 0); 1332 if (ret > 0) { 1333 bh_result->b_size = (ret << inode->i_blkbits); 1334 ret = 0; 1335 } 1336 if (started) 1337 ext4_journal_stop(handle); 1338 out: 1339 return ret; 1340 } 1341 1342 /* 1343 * `handle' can be NULL if create is zero 1344 */ 1345 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode, 1346 ext4_lblk_t block, int create, int *errp) 1347 { 1348 struct buffer_head dummy; 1349 int fatal = 0, err; 1350 int flags = 0; 1351 1352 J_ASSERT(handle != NULL || create == 0); 1353 1354 dummy.b_state = 0; 1355 dummy.b_blocknr = -1000; 1356 buffer_trace_init(&dummy.b_history); 1357 if (create) 1358 flags |= EXT4_GET_BLOCKS_CREATE; 1359 err = ext4_get_blocks(handle, inode, block, 1, &dummy, flags); 1360 /* 1361 * ext4_get_blocks() returns number of blocks mapped. 0 in 1362 * case of a HOLE. 1363 */ 1364 if (err > 0) { 1365 if (err > 1) 1366 WARN_ON(1); 1367 err = 0; 1368 } 1369 *errp = err; 1370 if (!err && buffer_mapped(&dummy)) { 1371 struct buffer_head *bh; 1372 bh = sb_getblk(inode->i_sb, dummy.b_blocknr); 1373 if (!bh) { 1374 *errp = -EIO; 1375 goto err; 1376 } 1377 if (buffer_new(&dummy)) { 1378 J_ASSERT(create != 0); 1379 J_ASSERT(handle != NULL); 1380 1381 /* 1382 * Now that we do not always journal data, we should 1383 * keep in mind whether this should always journal the 1384 * new buffer as metadata. For now, regular file 1385 * writes use ext4_get_block instead, so it's not a 1386 * problem. 1387 */ 1388 lock_buffer(bh); 1389 BUFFER_TRACE(bh, "call get_create_access"); 1390 fatal = ext4_journal_get_create_access(handle, bh); 1391 if (!fatal && !buffer_uptodate(bh)) { 1392 memset(bh->b_data, 0, inode->i_sb->s_blocksize); 1393 set_buffer_uptodate(bh); 1394 } 1395 unlock_buffer(bh); 1396 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata"); 1397 err = ext4_handle_dirty_metadata(handle, inode, bh); 1398 if (!fatal) 1399 fatal = err; 1400 } else { 1401 BUFFER_TRACE(bh, "not a new buffer"); 1402 } 1403 if (fatal) { 1404 *errp = fatal; 1405 brelse(bh); 1406 bh = NULL; 1407 } 1408 return bh; 1409 } 1410 err: 1411 return NULL; 1412 } 1413 1414 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode, 1415 ext4_lblk_t block, int create, int *err) 1416 { 1417 struct buffer_head *bh; 1418 1419 bh = ext4_getblk(handle, inode, block, create, err); 1420 if (!bh) 1421 return bh; 1422 if (buffer_uptodate(bh)) 1423 return bh; 1424 ll_rw_block(READ_META, 1, &bh); 1425 wait_on_buffer(bh); 1426 if (buffer_uptodate(bh)) 1427 return bh; 1428 put_bh(bh); 1429 *err = -EIO; 1430 return NULL; 1431 } 1432 1433 static int walk_page_buffers(handle_t *handle, 1434 struct buffer_head *head, 1435 unsigned from, 1436 unsigned to, 1437 int *partial, 1438 int (*fn)(handle_t *handle, 1439 struct buffer_head *bh)) 1440 { 1441 struct buffer_head *bh; 1442 unsigned block_start, block_end; 1443 unsigned blocksize = head->b_size; 1444 int err, ret = 0; 1445 struct buffer_head *next; 1446 1447 for (bh = head, block_start = 0; 1448 ret == 0 && (bh != head || !block_start); 1449 block_start = block_end, bh = next) { 1450 next = bh->b_this_page; 1451 block_end = block_start + blocksize; 1452 if (block_end <= from || block_start >= to) { 1453 if (partial && !buffer_uptodate(bh)) 1454 *partial = 1; 1455 continue; 1456 } 1457 err = (*fn)(handle, bh); 1458 if (!ret) 1459 ret = err; 1460 } 1461 return ret; 1462 } 1463 1464 /* 1465 * To preserve ordering, it is essential that the hole instantiation and 1466 * the data write be encapsulated in a single transaction. We cannot 1467 * close off a transaction and start a new one between the ext4_get_block() 1468 * and the commit_write(). So doing the jbd2_journal_start at the start of 1469 * prepare_write() is the right place. 1470 * 1471 * Also, this function can nest inside ext4_writepage() -> 1472 * block_write_full_page(). In that case, we *know* that ext4_writepage() 1473 * has generated enough buffer credits to do the whole page. So we won't 1474 * block on the journal in that case, which is good, because the caller may 1475 * be PF_MEMALLOC. 1476 * 1477 * By accident, ext4 can be reentered when a transaction is open via 1478 * quota file writes. If we were to commit the transaction while thus 1479 * reentered, there can be a deadlock - we would be holding a quota 1480 * lock, and the commit would never complete if another thread had a 1481 * transaction open and was blocking on the quota lock - a ranking 1482 * violation. 1483 * 1484 * So what we do is to rely on the fact that jbd2_journal_stop/journal_start 1485 * will _not_ run commit under these circumstances because handle->h_ref 1486 * is elevated. We'll still have enough credits for the tiny quotafile 1487 * write. 1488 */ 1489 static int do_journal_get_write_access(handle_t *handle, 1490 struct buffer_head *bh) 1491 { 1492 if (!buffer_mapped(bh) || buffer_freed(bh)) 1493 return 0; 1494 return ext4_journal_get_write_access(handle, bh); 1495 } 1496 1497 /* 1498 * Truncate blocks that were not used by write. We have to truncate the 1499 * pagecache as well so that corresponding buffers get properly unmapped. 1500 */ 1501 static void ext4_truncate_failed_write(struct inode *inode) 1502 { 1503 truncate_inode_pages(inode->i_mapping, inode->i_size); 1504 ext4_truncate(inode); 1505 } 1506 1507 static int ext4_write_begin(struct file *file, struct address_space *mapping, 1508 loff_t pos, unsigned len, unsigned flags, 1509 struct page **pagep, void **fsdata) 1510 { 1511 struct inode *inode = mapping->host; 1512 int ret, needed_blocks; 1513 handle_t *handle; 1514 int retries = 0; 1515 struct page *page; 1516 pgoff_t index; 1517 unsigned from, to; 1518 1519 trace_ext4_write_begin(inode, pos, len, flags); 1520 /* 1521 * Reserve one block more for addition to orphan list in case 1522 * we allocate blocks but write fails for some reason 1523 */ 1524 needed_blocks = ext4_writepage_trans_blocks(inode) + 1; 1525 index = pos >> PAGE_CACHE_SHIFT; 1526 from = pos & (PAGE_CACHE_SIZE - 1); 1527 to = from + len; 1528 1529 retry: 1530 handle = ext4_journal_start(inode, needed_blocks); 1531 if (IS_ERR(handle)) { 1532 ret = PTR_ERR(handle); 1533 goto out; 1534 } 1535 1536 /* We cannot recurse into the filesystem as the transaction is already 1537 * started */ 1538 flags |= AOP_FLAG_NOFS; 1539 1540 page = grab_cache_page_write_begin(mapping, index, flags); 1541 if (!page) { 1542 ext4_journal_stop(handle); 1543 ret = -ENOMEM; 1544 goto out; 1545 } 1546 *pagep = page; 1547 1548 ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata, 1549 ext4_get_block); 1550 1551 if (!ret && ext4_should_journal_data(inode)) { 1552 ret = walk_page_buffers(handle, page_buffers(page), 1553 from, to, NULL, do_journal_get_write_access); 1554 } 1555 1556 if (ret) { 1557 unlock_page(page); 1558 page_cache_release(page); 1559 /* 1560 * block_write_begin may have instantiated a few blocks 1561 * outside i_size. Trim these off again. Don't need 1562 * i_size_read because we hold i_mutex. 1563 * 1564 * Add inode to orphan list in case we crash before 1565 * truncate finishes 1566 */ 1567 if (pos + len > inode->i_size && ext4_can_truncate(inode)) 1568 ext4_orphan_add(handle, inode); 1569 1570 ext4_journal_stop(handle); 1571 if (pos + len > inode->i_size) { 1572 ext4_truncate_failed_write(inode); 1573 /* 1574 * If truncate failed early the inode might 1575 * still be on the orphan list; we need to 1576 * make sure the inode is removed from the 1577 * orphan list in that case. 1578 */ 1579 if (inode->i_nlink) 1580 ext4_orphan_del(NULL, inode); 1581 } 1582 } 1583 1584 if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 1585 goto retry; 1586 out: 1587 return ret; 1588 } 1589 1590 /* For write_end() in data=journal mode */ 1591 static int write_end_fn(handle_t *handle, struct buffer_head *bh) 1592 { 1593 if (!buffer_mapped(bh) || buffer_freed(bh)) 1594 return 0; 1595 set_buffer_uptodate(bh); 1596 return ext4_handle_dirty_metadata(handle, NULL, bh); 1597 } 1598 1599 static int ext4_generic_write_end(struct file *file, 1600 struct address_space *mapping, 1601 loff_t pos, unsigned len, unsigned copied, 1602 struct page *page, void *fsdata) 1603 { 1604 int i_size_changed = 0; 1605 struct inode *inode = mapping->host; 1606 handle_t *handle = ext4_journal_current_handle(); 1607 1608 copied = block_write_end(file, mapping, pos, len, copied, page, fsdata); 1609 1610 /* 1611 * No need to use i_size_read() here, the i_size 1612 * cannot change under us because we hold i_mutex. 1613 * 1614 * But it's important to update i_size while still holding page lock: 1615 * page writeout could otherwise come in and zero beyond i_size. 1616 */ 1617 if (pos + copied > inode->i_size) { 1618 i_size_write(inode, pos + copied); 1619 i_size_changed = 1; 1620 } 1621 1622 if (pos + copied > EXT4_I(inode)->i_disksize) { 1623 /* We need to mark inode dirty even if 1624 * new_i_size is less that inode->i_size 1625 * bu greater than i_disksize.(hint delalloc) 1626 */ 1627 ext4_update_i_disksize(inode, (pos + copied)); 1628 i_size_changed = 1; 1629 } 1630 unlock_page(page); 1631 page_cache_release(page); 1632 1633 /* 1634 * Don't mark the inode dirty under page lock. First, it unnecessarily 1635 * makes the holding time of page lock longer. Second, it forces lock 1636 * ordering of page lock and transaction start for journaling 1637 * filesystems. 1638 */ 1639 if (i_size_changed) 1640 ext4_mark_inode_dirty(handle, inode); 1641 1642 return copied; 1643 } 1644 1645 /* 1646 * We need to pick up the new inode size which generic_commit_write gave us 1647 * `file' can be NULL - eg, when called from page_symlink(). 1648 * 1649 * ext4 never places buffers on inode->i_mapping->private_list. metadata 1650 * buffers are managed internally. 1651 */ 1652 static int ext4_ordered_write_end(struct file *file, 1653 struct address_space *mapping, 1654 loff_t pos, unsigned len, unsigned copied, 1655 struct page *page, void *fsdata) 1656 { 1657 handle_t *handle = ext4_journal_current_handle(); 1658 struct inode *inode = mapping->host; 1659 int ret = 0, ret2; 1660 1661 trace_ext4_ordered_write_end(inode, pos, len, copied); 1662 ret = ext4_jbd2_file_inode(handle, inode); 1663 1664 if (ret == 0) { 1665 ret2 = ext4_generic_write_end(file, mapping, pos, len, copied, 1666 page, fsdata); 1667 copied = ret2; 1668 if (pos + len > inode->i_size && ext4_can_truncate(inode)) 1669 /* if we have allocated more blocks and copied 1670 * less. We will have blocks allocated outside 1671 * inode->i_size. So truncate them 1672 */ 1673 ext4_orphan_add(handle, inode); 1674 if (ret2 < 0) 1675 ret = ret2; 1676 } 1677 ret2 = ext4_journal_stop(handle); 1678 if (!ret) 1679 ret = ret2; 1680 1681 if (pos + len > inode->i_size) { 1682 ext4_truncate_failed_write(inode); 1683 /* 1684 * If truncate failed early the inode might still be 1685 * on the orphan list; we need to make sure the inode 1686 * is removed from the orphan list in that case. 1687 */ 1688 if (inode->i_nlink) 1689 ext4_orphan_del(NULL, inode); 1690 } 1691 1692 1693 return ret ? ret : copied; 1694 } 1695 1696 static int ext4_writeback_write_end(struct file *file, 1697 struct address_space *mapping, 1698 loff_t pos, unsigned len, unsigned copied, 1699 struct page *page, void *fsdata) 1700 { 1701 handle_t *handle = ext4_journal_current_handle(); 1702 struct inode *inode = mapping->host; 1703 int ret = 0, ret2; 1704 1705 trace_ext4_writeback_write_end(inode, pos, len, copied); 1706 ret2 = ext4_generic_write_end(file, mapping, pos, len, copied, 1707 page, fsdata); 1708 copied = ret2; 1709 if (pos + len > inode->i_size && ext4_can_truncate(inode)) 1710 /* if we have allocated more blocks and copied 1711 * less. We will have blocks allocated outside 1712 * inode->i_size. So truncate them 1713 */ 1714 ext4_orphan_add(handle, inode); 1715 1716 if (ret2 < 0) 1717 ret = ret2; 1718 1719 ret2 = ext4_journal_stop(handle); 1720 if (!ret) 1721 ret = ret2; 1722 1723 if (pos + len > inode->i_size) { 1724 ext4_truncate_failed_write(inode); 1725 /* 1726 * If truncate failed early the inode might still be 1727 * on the orphan list; we need to make sure the inode 1728 * is removed from the orphan list in that case. 1729 */ 1730 if (inode->i_nlink) 1731 ext4_orphan_del(NULL, inode); 1732 } 1733 1734 return ret ? ret : copied; 1735 } 1736 1737 static int ext4_journalled_write_end(struct file *file, 1738 struct address_space *mapping, 1739 loff_t pos, unsigned len, unsigned copied, 1740 struct page *page, void *fsdata) 1741 { 1742 handle_t *handle = ext4_journal_current_handle(); 1743 struct inode *inode = mapping->host; 1744 int ret = 0, ret2; 1745 int partial = 0; 1746 unsigned from, to; 1747 loff_t new_i_size; 1748 1749 trace_ext4_journalled_write_end(inode, pos, len, copied); 1750 from = pos & (PAGE_CACHE_SIZE - 1); 1751 to = from + len; 1752 1753 if (copied < len) { 1754 if (!PageUptodate(page)) 1755 copied = 0; 1756 page_zero_new_buffers(page, from+copied, to); 1757 } 1758 1759 ret = walk_page_buffers(handle, page_buffers(page), from, 1760 to, &partial, write_end_fn); 1761 if (!partial) 1762 SetPageUptodate(page); 1763 new_i_size = pos + copied; 1764 if (new_i_size > inode->i_size) 1765 i_size_write(inode, pos+copied); 1766 EXT4_I(inode)->i_state |= EXT4_STATE_JDATA; 1767 if (new_i_size > EXT4_I(inode)->i_disksize) { 1768 ext4_update_i_disksize(inode, new_i_size); 1769 ret2 = ext4_mark_inode_dirty(handle, inode); 1770 if (!ret) 1771 ret = ret2; 1772 } 1773 1774 unlock_page(page); 1775 page_cache_release(page); 1776 if (pos + len > inode->i_size && ext4_can_truncate(inode)) 1777 /* if we have allocated more blocks and copied 1778 * less. We will have blocks allocated outside 1779 * inode->i_size. So truncate them 1780 */ 1781 ext4_orphan_add(handle, inode); 1782 1783 ret2 = ext4_journal_stop(handle); 1784 if (!ret) 1785 ret = ret2; 1786 if (pos + len > inode->i_size) { 1787 ext4_truncate_failed_write(inode); 1788 /* 1789 * If truncate failed early the inode might still be 1790 * on the orphan list; we need to make sure the inode 1791 * is removed from the orphan list in that case. 1792 */ 1793 if (inode->i_nlink) 1794 ext4_orphan_del(NULL, inode); 1795 } 1796 1797 return ret ? ret : copied; 1798 } 1799 1800 static int ext4_da_reserve_space(struct inode *inode, int nrblocks) 1801 { 1802 int retries = 0; 1803 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 1804 unsigned long md_needed, mdblocks, total = 0; 1805 1806 /* 1807 * recalculate the amount of metadata blocks to reserve 1808 * in order to allocate nrblocks 1809 * worse case is one extent per block 1810 */ 1811 repeat: 1812 spin_lock(&EXT4_I(inode)->i_block_reservation_lock); 1813 total = EXT4_I(inode)->i_reserved_data_blocks + nrblocks; 1814 mdblocks = ext4_calc_metadata_amount(inode, total); 1815 BUG_ON(mdblocks < EXT4_I(inode)->i_reserved_meta_blocks); 1816 1817 md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks; 1818 total = md_needed + nrblocks; 1819 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 1820 1821 /* 1822 * Make quota reservation here to prevent quota overflow 1823 * later. Real quota accounting is done at pages writeout 1824 * time. 1825 */ 1826 if (vfs_dq_reserve_block(inode, total)) 1827 return -EDQUOT; 1828 1829 if (ext4_claim_free_blocks(sbi, total)) { 1830 vfs_dq_release_reservation_block(inode, total); 1831 if (ext4_should_retry_alloc(inode->i_sb, &retries)) { 1832 yield(); 1833 goto repeat; 1834 } 1835 return -ENOSPC; 1836 } 1837 spin_lock(&EXT4_I(inode)->i_block_reservation_lock); 1838 EXT4_I(inode)->i_reserved_data_blocks += nrblocks; 1839 EXT4_I(inode)->i_reserved_meta_blocks += md_needed; 1840 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 1841 1842 return 0; /* success */ 1843 } 1844 1845 static void ext4_da_release_space(struct inode *inode, int to_free) 1846 { 1847 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 1848 int total, mdb, mdb_free, release; 1849 1850 if (!to_free) 1851 return; /* Nothing to release, exit */ 1852 1853 spin_lock(&EXT4_I(inode)->i_block_reservation_lock); 1854 1855 if (!EXT4_I(inode)->i_reserved_data_blocks) { 1856 /* 1857 * if there is no reserved blocks, but we try to free some 1858 * then the counter is messed up somewhere. 1859 * but since this function is called from invalidate 1860 * page, it's harmless to return without any action 1861 */ 1862 printk(KERN_INFO "ext4 delalloc try to release %d reserved " 1863 "blocks for inode %lu, but there is no reserved " 1864 "data blocks\n", to_free, inode->i_ino); 1865 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 1866 return; 1867 } 1868 1869 /* recalculate the number of metablocks still need to be reserved */ 1870 total = EXT4_I(inode)->i_reserved_data_blocks - to_free; 1871 mdb = ext4_calc_metadata_amount(inode, total); 1872 1873 /* figure out how many metablocks to release */ 1874 BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks); 1875 mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb; 1876 1877 release = to_free + mdb_free; 1878 1879 /* update fs dirty blocks counter for truncate case */ 1880 percpu_counter_sub(&sbi->s_dirtyblocks_counter, release); 1881 1882 /* update per-inode reservations */ 1883 BUG_ON(to_free > EXT4_I(inode)->i_reserved_data_blocks); 1884 EXT4_I(inode)->i_reserved_data_blocks -= to_free; 1885 1886 BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks); 1887 EXT4_I(inode)->i_reserved_meta_blocks = mdb; 1888 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 1889 1890 vfs_dq_release_reservation_block(inode, release); 1891 } 1892 1893 static void ext4_da_page_release_reservation(struct page *page, 1894 unsigned long offset) 1895 { 1896 int to_release = 0; 1897 struct buffer_head *head, *bh; 1898 unsigned int curr_off = 0; 1899 1900 head = page_buffers(page); 1901 bh = head; 1902 do { 1903 unsigned int next_off = curr_off + bh->b_size; 1904 1905 if ((offset <= curr_off) && (buffer_delay(bh))) { 1906 to_release++; 1907 clear_buffer_delay(bh); 1908 } 1909 curr_off = next_off; 1910 } while ((bh = bh->b_this_page) != head); 1911 ext4_da_release_space(page->mapping->host, to_release); 1912 } 1913 1914 /* 1915 * Delayed allocation stuff 1916 */ 1917 1918 /* 1919 * mpage_da_submit_io - walks through extent of pages and try to write 1920 * them with writepage() call back 1921 * 1922 * @mpd->inode: inode 1923 * @mpd->first_page: first page of the extent 1924 * @mpd->next_page: page after the last page of the extent 1925 * 1926 * By the time mpage_da_submit_io() is called we expect all blocks 1927 * to be allocated. this may be wrong if allocation failed. 1928 * 1929 * As pages are already locked by write_cache_pages(), we can't use it 1930 */ 1931 static int mpage_da_submit_io(struct mpage_da_data *mpd) 1932 { 1933 long pages_skipped; 1934 struct pagevec pvec; 1935 unsigned long index, end; 1936 int ret = 0, err, nr_pages, i; 1937 struct inode *inode = mpd->inode; 1938 struct address_space *mapping = inode->i_mapping; 1939 1940 BUG_ON(mpd->next_page <= mpd->first_page); 1941 /* 1942 * We need to start from the first_page to the next_page - 1 1943 * to make sure we also write the mapped dirty buffer_heads. 1944 * If we look at mpd->b_blocknr we would only be looking 1945 * at the currently mapped buffer_heads. 1946 */ 1947 index = mpd->first_page; 1948 end = mpd->next_page - 1; 1949 1950 pagevec_init(&pvec, 0); 1951 while (index <= end) { 1952 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE); 1953 if (nr_pages == 0) 1954 break; 1955 for (i = 0; i < nr_pages; i++) { 1956 struct page *page = pvec.pages[i]; 1957 1958 index = page->index; 1959 if (index > end) 1960 break; 1961 index++; 1962 1963 BUG_ON(!PageLocked(page)); 1964 BUG_ON(PageWriteback(page)); 1965 1966 pages_skipped = mpd->wbc->pages_skipped; 1967 err = mapping->a_ops->writepage(page, mpd->wbc); 1968 if (!err && (pages_skipped == mpd->wbc->pages_skipped)) 1969 /* 1970 * have successfully written the page 1971 * without skipping the same 1972 */ 1973 mpd->pages_written++; 1974 /* 1975 * In error case, we have to continue because 1976 * remaining pages are still locked 1977 * XXX: unlock and re-dirty them? 1978 */ 1979 if (ret == 0) 1980 ret = err; 1981 } 1982 pagevec_release(&pvec); 1983 } 1984 return ret; 1985 } 1986 1987 /* 1988 * mpage_put_bnr_to_bhs - walk blocks and assign them actual numbers 1989 * 1990 * @mpd->inode - inode to walk through 1991 * @exbh->b_blocknr - first block on a disk 1992 * @exbh->b_size - amount of space in bytes 1993 * @logical - first logical block to start assignment with 1994 * 1995 * the function goes through all passed space and put actual disk 1996 * block numbers into buffer heads, dropping BH_Delay and BH_Unwritten 1997 */ 1998 static void mpage_put_bnr_to_bhs(struct mpage_da_data *mpd, sector_t logical, 1999 struct buffer_head *exbh) 2000 { 2001 struct inode *inode = mpd->inode; 2002 struct address_space *mapping = inode->i_mapping; 2003 int blocks = exbh->b_size >> inode->i_blkbits; 2004 sector_t pblock = exbh->b_blocknr, cur_logical; 2005 struct buffer_head *head, *bh; 2006 pgoff_t index, end; 2007 struct pagevec pvec; 2008 int nr_pages, i; 2009 2010 index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits); 2011 end = (logical + blocks - 1) >> (PAGE_CACHE_SHIFT - inode->i_blkbits); 2012 cur_logical = index << (PAGE_CACHE_SHIFT - inode->i_blkbits); 2013 2014 pagevec_init(&pvec, 0); 2015 2016 while (index <= end) { 2017 /* XXX: optimize tail */ 2018 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE); 2019 if (nr_pages == 0) 2020 break; 2021 for (i = 0; i < nr_pages; i++) { 2022 struct page *page = pvec.pages[i]; 2023 2024 index = page->index; 2025 if (index > end) 2026 break; 2027 index++; 2028 2029 BUG_ON(!PageLocked(page)); 2030 BUG_ON(PageWriteback(page)); 2031 BUG_ON(!page_has_buffers(page)); 2032 2033 bh = page_buffers(page); 2034 head = bh; 2035 2036 /* skip blocks out of the range */ 2037 do { 2038 if (cur_logical >= logical) 2039 break; 2040 cur_logical++; 2041 } while ((bh = bh->b_this_page) != head); 2042 2043 do { 2044 if (cur_logical >= logical + blocks) 2045 break; 2046 2047 if (buffer_delay(bh) || 2048 buffer_unwritten(bh)) { 2049 2050 BUG_ON(bh->b_bdev != inode->i_sb->s_bdev); 2051 2052 if (buffer_delay(bh)) { 2053 clear_buffer_delay(bh); 2054 bh->b_blocknr = pblock; 2055 } else { 2056 /* 2057 * unwritten already should have 2058 * blocknr assigned. Verify that 2059 */ 2060 clear_buffer_unwritten(bh); 2061 BUG_ON(bh->b_blocknr != pblock); 2062 } 2063 2064 } else if (buffer_mapped(bh)) 2065 BUG_ON(bh->b_blocknr != pblock); 2066 2067 cur_logical++; 2068 pblock++; 2069 } while ((bh = bh->b_this_page) != head); 2070 } 2071 pagevec_release(&pvec); 2072 } 2073 } 2074 2075 2076 /* 2077 * __unmap_underlying_blocks - just a helper function to unmap 2078 * set of blocks described by @bh 2079 */ 2080 static inline void __unmap_underlying_blocks(struct inode *inode, 2081 struct buffer_head *bh) 2082 { 2083 struct block_device *bdev = inode->i_sb->s_bdev; 2084 int blocks, i; 2085 2086 blocks = bh->b_size >> inode->i_blkbits; 2087 for (i = 0; i < blocks; i++) 2088 unmap_underlying_metadata(bdev, bh->b_blocknr + i); 2089 } 2090 2091 static void ext4_da_block_invalidatepages(struct mpage_da_data *mpd, 2092 sector_t logical, long blk_cnt) 2093 { 2094 int nr_pages, i; 2095 pgoff_t index, end; 2096 struct pagevec pvec; 2097 struct inode *inode = mpd->inode; 2098 struct address_space *mapping = inode->i_mapping; 2099 2100 index = logical >> (PAGE_CACHE_SHIFT - inode->i_blkbits); 2101 end = (logical + blk_cnt - 1) >> 2102 (PAGE_CACHE_SHIFT - inode->i_blkbits); 2103 while (index <= end) { 2104 nr_pages = pagevec_lookup(&pvec, mapping, index, PAGEVEC_SIZE); 2105 if (nr_pages == 0) 2106 break; 2107 for (i = 0; i < nr_pages; i++) { 2108 struct page *page = pvec.pages[i]; 2109 index = page->index; 2110 if (index > end) 2111 break; 2112 index++; 2113 2114 BUG_ON(!PageLocked(page)); 2115 BUG_ON(PageWriteback(page)); 2116 block_invalidatepage(page, 0); 2117 ClearPageUptodate(page); 2118 unlock_page(page); 2119 } 2120 } 2121 return; 2122 } 2123 2124 static void ext4_print_free_blocks(struct inode *inode) 2125 { 2126 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 2127 printk(KERN_CRIT "Total free blocks count %lld\n", 2128 ext4_count_free_blocks(inode->i_sb)); 2129 printk(KERN_CRIT "Free/Dirty block details\n"); 2130 printk(KERN_CRIT "free_blocks=%lld\n", 2131 (long long) percpu_counter_sum(&sbi->s_freeblocks_counter)); 2132 printk(KERN_CRIT "dirty_blocks=%lld\n", 2133 (long long) percpu_counter_sum(&sbi->s_dirtyblocks_counter)); 2134 printk(KERN_CRIT "Block reservation details\n"); 2135 printk(KERN_CRIT "i_reserved_data_blocks=%u\n", 2136 EXT4_I(inode)->i_reserved_data_blocks); 2137 printk(KERN_CRIT "i_reserved_meta_blocks=%u\n", 2138 EXT4_I(inode)->i_reserved_meta_blocks); 2139 return; 2140 } 2141 2142 /* 2143 * mpage_da_map_blocks - go through given space 2144 * 2145 * @mpd - bh describing space 2146 * 2147 * The function skips space we know is already mapped to disk blocks. 2148 * 2149 */ 2150 static int mpage_da_map_blocks(struct mpage_da_data *mpd) 2151 { 2152 int err, blks, get_blocks_flags; 2153 struct buffer_head new; 2154 sector_t next = mpd->b_blocknr; 2155 unsigned max_blocks = mpd->b_size >> mpd->inode->i_blkbits; 2156 loff_t disksize = EXT4_I(mpd->inode)->i_disksize; 2157 handle_t *handle = NULL; 2158 2159 /* 2160 * We consider only non-mapped and non-allocated blocks 2161 */ 2162 if ((mpd->b_state & (1 << BH_Mapped)) && 2163 !(mpd->b_state & (1 << BH_Delay)) && 2164 !(mpd->b_state & (1 << BH_Unwritten))) 2165 return 0; 2166 2167 /* 2168 * If we didn't accumulate anything to write simply return 2169 */ 2170 if (!mpd->b_size) 2171 return 0; 2172 2173 handle = ext4_journal_current_handle(); 2174 BUG_ON(!handle); 2175 2176 /* 2177 * Call ext4_get_blocks() to allocate any delayed allocation 2178 * blocks, or to convert an uninitialized extent to be 2179 * initialized (in the case where we have written into 2180 * one or more preallocated blocks). 2181 * 2182 * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE to 2183 * indicate that we are on the delayed allocation path. This 2184 * affects functions in many different parts of the allocation 2185 * call path. This flag exists primarily because we don't 2186 * want to change *many* call functions, so ext4_get_blocks() 2187 * will set the magic i_delalloc_reserved_flag once the 2188 * inode's allocation semaphore is taken. 2189 * 2190 * If the blocks in questions were delalloc blocks, set 2191 * EXT4_GET_BLOCKS_DELALLOC_RESERVE so the delalloc accounting 2192 * variables are updated after the blocks have been allocated. 2193 */ 2194 new.b_state = 0; 2195 get_blocks_flags = (EXT4_GET_BLOCKS_CREATE | 2196 EXT4_GET_BLOCKS_DELALLOC_RESERVE); 2197 if (mpd->b_state & (1 << BH_Delay)) 2198 get_blocks_flags |= EXT4_GET_BLOCKS_UPDATE_RESERVE_SPACE; 2199 blks = ext4_get_blocks(handle, mpd->inode, next, max_blocks, 2200 &new, get_blocks_flags); 2201 if (blks < 0) { 2202 err = blks; 2203 /* 2204 * If get block returns with error we simply 2205 * return. Later writepage will redirty the page and 2206 * writepages will find the dirty page again 2207 */ 2208 if (err == -EAGAIN) 2209 return 0; 2210 2211 if (err == -ENOSPC && 2212 ext4_count_free_blocks(mpd->inode->i_sb)) { 2213 mpd->retval = err; 2214 return 0; 2215 } 2216 2217 /* 2218 * get block failure will cause us to loop in 2219 * writepages, because a_ops->writepage won't be able 2220 * to make progress. The page will be redirtied by 2221 * writepage and writepages will again try to write 2222 * the same. 2223 */ 2224 ext4_msg(mpd->inode->i_sb, KERN_CRIT, 2225 "delayed block allocation failed for inode %lu at " 2226 "logical offset %llu with max blocks %zd with " 2227 "error %d\n", mpd->inode->i_ino, 2228 (unsigned long long) next, 2229 mpd->b_size >> mpd->inode->i_blkbits, err); 2230 printk(KERN_CRIT "This should not happen!! " 2231 "Data will be lost\n"); 2232 if (err == -ENOSPC) { 2233 ext4_print_free_blocks(mpd->inode); 2234 } 2235 /* invalidate all the pages */ 2236 ext4_da_block_invalidatepages(mpd, next, 2237 mpd->b_size >> mpd->inode->i_blkbits); 2238 return err; 2239 } 2240 BUG_ON(blks == 0); 2241 2242 new.b_size = (blks << mpd->inode->i_blkbits); 2243 2244 if (buffer_new(&new)) 2245 __unmap_underlying_blocks(mpd->inode, &new); 2246 2247 /* 2248 * If blocks are delayed marked, we need to 2249 * put actual blocknr and drop delayed bit 2250 */ 2251 if ((mpd->b_state & (1 << BH_Delay)) || 2252 (mpd->b_state & (1 << BH_Unwritten))) 2253 mpage_put_bnr_to_bhs(mpd, next, &new); 2254 2255 if (ext4_should_order_data(mpd->inode)) { 2256 err = ext4_jbd2_file_inode(handle, mpd->inode); 2257 if (err) 2258 return err; 2259 } 2260 2261 /* 2262 * Update on-disk size along with block allocation. 2263 */ 2264 disksize = ((loff_t) next + blks) << mpd->inode->i_blkbits; 2265 if (disksize > i_size_read(mpd->inode)) 2266 disksize = i_size_read(mpd->inode); 2267 if (disksize > EXT4_I(mpd->inode)->i_disksize) { 2268 ext4_update_i_disksize(mpd->inode, disksize); 2269 return ext4_mark_inode_dirty(handle, mpd->inode); 2270 } 2271 2272 return 0; 2273 } 2274 2275 #define BH_FLAGS ((1 << BH_Uptodate) | (1 << BH_Mapped) | \ 2276 (1 << BH_Delay) | (1 << BH_Unwritten)) 2277 2278 /* 2279 * mpage_add_bh_to_extent - try to add one more block to extent of blocks 2280 * 2281 * @mpd->lbh - extent of blocks 2282 * @logical - logical number of the block in the file 2283 * @bh - bh of the block (used to access block's state) 2284 * 2285 * the function is used to collect contig. blocks in same state 2286 */ 2287 static void mpage_add_bh_to_extent(struct mpage_da_data *mpd, 2288 sector_t logical, size_t b_size, 2289 unsigned long b_state) 2290 { 2291 sector_t next; 2292 int nrblocks = mpd->b_size >> mpd->inode->i_blkbits; 2293 2294 /* check if thereserved journal credits might overflow */ 2295 if (!(EXT4_I(mpd->inode)->i_flags & EXT4_EXTENTS_FL)) { 2296 if (nrblocks >= EXT4_MAX_TRANS_DATA) { 2297 /* 2298 * With non-extent format we are limited by the journal 2299 * credit available. Total credit needed to insert 2300 * nrblocks contiguous blocks is dependent on the 2301 * nrblocks. So limit nrblocks. 2302 */ 2303 goto flush_it; 2304 } else if ((nrblocks + (b_size >> mpd->inode->i_blkbits)) > 2305 EXT4_MAX_TRANS_DATA) { 2306 /* 2307 * Adding the new buffer_head would make it cross the 2308 * allowed limit for which we have journal credit 2309 * reserved. So limit the new bh->b_size 2310 */ 2311 b_size = (EXT4_MAX_TRANS_DATA - nrblocks) << 2312 mpd->inode->i_blkbits; 2313 /* we will do mpage_da_submit_io in the next loop */ 2314 } 2315 } 2316 /* 2317 * First block in the extent 2318 */ 2319 if (mpd->b_size == 0) { 2320 mpd->b_blocknr = logical; 2321 mpd->b_size = b_size; 2322 mpd->b_state = b_state & BH_FLAGS; 2323 return; 2324 } 2325 2326 next = mpd->b_blocknr + nrblocks; 2327 /* 2328 * Can we merge the block to our big extent? 2329 */ 2330 if (logical == next && (b_state & BH_FLAGS) == mpd->b_state) { 2331 mpd->b_size += b_size; 2332 return; 2333 } 2334 2335 flush_it: 2336 /* 2337 * We couldn't merge the block to our extent, so we 2338 * need to flush current extent and start new one 2339 */ 2340 if (mpage_da_map_blocks(mpd) == 0) 2341 mpage_da_submit_io(mpd); 2342 mpd->io_done = 1; 2343 return; 2344 } 2345 2346 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh) 2347 { 2348 return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh); 2349 } 2350 2351 /* 2352 * __mpage_da_writepage - finds extent of pages and blocks 2353 * 2354 * @page: page to consider 2355 * @wbc: not used, we just follow rules 2356 * @data: context 2357 * 2358 * The function finds extents of pages and scan them for all blocks. 2359 */ 2360 static int __mpage_da_writepage(struct page *page, 2361 struct writeback_control *wbc, void *data) 2362 { 2363 struct mpage_da_data *mpd = data; 2364 struct inode *inode = mpd->inode; 2365 struct buffer_head *bh, *head; 2366 sector_t logical; 2367 2368 if (mpd->io_done) { 2369 /* 2370 * Rest of the page in the page_vec 2371 * redirty then and skip then. We will 2372 * try to write them again after 2373 * starting a new transaction 2374 */ 2375 redirty_page_for_writepage(wbc, page); 2376 unlock_page(page); 2377 return MPAGE_DA_EXTENT_TAIL; 2378 } 2379 /* 2380 * Can we merge this page to current extent? 2381 */ 2382 if (mpd->next_page != page->index) { 2383 /* 2384 * Nope, we can't. So, we map non-allocated blocks 2385 * and start IO on them using writepage() 2386 */ 2387 if (mpd->next_page != mpd->first_page) { 2388 if (mpage_da_map_blocks(mpd) == 0) 2389 mpage_da_submit_io(mpd); 2390 /* 2391 * skip rest of the page in the page_vec 2392 */ 2393 mpd->io_done = 1; 2394 redirty_page_for_writepage(wbc, page); 2395 unlock_page(page); 2396 return MPAGE_DA_EXTENT_TAIL; 2397 } 2398 2399 /* 2400 * Start next extent of pages ... 2401 */ 2402 mpd->first_page = page->index; 2403 2404 /* 2405 * ... and blocks 2406 */ 2407 mpd->b_size = 0; 2408 mpd->b_state = 0; 2409 mpd->b_blocknr = 0; 2410 } 2411 2412 mpd->next_page = page->index + 1; 2413 logical = (sector_t) page->index << 2414 (PAGE_CACHE_SHIFT - inode->i_blkbits); 2415 2416 if (!page_has_buffers(page)) { 2417 mpage_add_bh_to_extent(mpd, logical, PAGE_CACHE_SIZE, 2418 (1 << BH_Dirty) | (1 << BH_Uptodate)); 2419 if (mpd->io_done) 2420 return MPAGE_DA_EXTENT_TAIL; 2421 } else { 2422 /* 2423 * Page with regular buffer heads, just add all dirty ones 2424 */ 2425 head = page_buffers(page); 2426 bh = head; 2427 do { 2428 BUG_ON(buffer_locked(bh)); 2429 /* 2430 * We need to try to allocate 2431 * unmapped blocks in the same page. 2432 * Otherwise we won't make progress 2433 * with the page in ext4_writepage 2434 */ 2435 if (ext4_bh_delay_or_unwritten(NULL, bh)) { 2436 mpage_add_bh_to_extent(mpd, logical, 2437 bh->b_size, 2438 bh->b_state); 2439 if (mpd->io_done) 2440 return MPAGE_DA_EXTENT_TAIL; 2441 } else if (buffer_dirty(bh) && (buffer_mapped(bh))) { 2442 /* 2443 * mapped dirty buffer. We need to update 2444 * the b_state because we look at 2445 * b_state in mpage_da_map_blocks. We don't 2446 * update b_size because if we find an 2447 * unmapped buffer_head later we need to 2448 * use the b_state flag of that buffer_head. 2449 */ 2450 if (mpd->b_size == 0) 2451 mpd->b_state = bh->b_state & BH_FLAGS; 2452 } 2453 logical++; 2454 } while ((bh = bh->b_this_page) != head); 2455 } 2456 2457 return 0; 2458 } 2459 2460 /* 2461 * This is a special get_blocks_t callback which is used by 2462 * ext4_da_write_begin(). It will either return mapped block or 2463 * reserve space for a single block. 2464 * 2465 * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set. 2466 * We also have b_blocknr = -1 and b_bdev initialized properly 2467 * 2468 * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set. 2469 * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev 2470 * initialized properly. 2471 */ 2472 static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock, 2473 struct buffer_head *bh_result, int create) 2474 { 2475 int ret = 0; 2476 sector_t invalid_block = ~((sector_t) 0xffff); 2477 2478 if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es)) 2479 invalid_block = ~0; 2480 2481 BUG_ON(create == 0); 2482 BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize); 2483 2484 /* 2485 * first, we need to know whether the block is allocated already 2486 * preallocated blocks are unmapped but should treated 2487 * the same as allocated blocks. 2488 */ 2489 ret = ext4_get_blocks(NULL, inode, iblock, 1, bh_result, 0); 2490 if ((ret == 0) && !buffer_delay(bh_result)) { 2491 /* the block isn't (pre)allocated yet, let's reserve space */ 2492 /* 2493 * XXX: __block_prepare_write() unmaps passed block, 2494 * is it OK? 2495 */ 2496 ret = ext4_da_reserve_space(inode, 1); 2497 if (ret) 2498 /* not enough space to reserve */ 2499 return ret; 2500 2501 map_bh(bh_result, inode->i_sb, invalid_block); 2502 set_buffer_new(bh_result); 2503 set_buffer_delay(bh_result); 2504 } else if (ret > 0) { 2505 bh_result->b_size = (ret << inode->i_blkbits); 2506 if (buffer_unwritten(bh_result)) { 2507 /* A delayed write to unwritten bh should 2508 * be marked new and mapped. Mapped ensures 2509 * that we don't do get_block multiple times 2510 * when we write to the same offset and new 2511 * ensures that we do proper zero out for 2512 * partial write. 2513 */ 2514 set_buffer_new(bh_result); 2515 set_buffer_mapped(bh_result); 2516 } 2517 ret = 0; 2518 } 2519 2520 return ret; 2521 } 2522 2523 /* 2524 * This function is used as a standard get_block_t calback function 2525 * when there is no desire to allocate any blocks. It is used as a 2526 * callback function for block_prepare_write(), nobh_writepage(), and 2527 * block_write_full_page(). These functions should only try to map a 2528 * single block at a time. 2529 * 2530 * Since this function doesn't do block allocations even if the caller 2531 * requests it by passing in create=1, it is critically important that 2532 * any caller checks to make sure that any buffer heads are returned 2533 * by this function are either all already mapped or marked for 2534 * delayed allocation before calling nobh_writepage() or 2535 * block_write_full_page(). Otherwise, b_blocknr could be left 2536 * unitialized, and the page write functions will be taken by 2537 * surprise. 2538 */ 2539 static int noalloc_get_block_write(struct inode *inode, sector_t iblock, 2540 struct buffer_head *bh_result, int create) 2541 { 2542 int ret = 0; 2543 unsigned max_blocks = bh_result->b_size >> inode->i_blkbits; 2544 2545 BUG_ON(bh_result->b_size != inode->i_sb->s_blocksize); 2546 2547 /* 2548 * we don't want to do block allocation in writepage 2549 * so call get_block_wrap with create = 0 2550 */ 2551 ret = ext4_get_blocks(NULL, inode, iblock, max_blocks, bh_result, 0); 2552 if (ret > 0) { 2553 bh_result->b_size = (ret << inode->i_blkbits); 2554 ret = 0; 2555 } 2556 return ret; 2557 } 2558 2559 static int bget_one(handle_t *handle, struct buffer_head *bh) 2560 { 2561 get_bh(bh); 2562 return 0; 2563 } 2564 2565 static int bput_one(handle_t *handle, struct buffer_head *bh) 2566 { 2567 put_bh(bh); 2568 return 0; 2569 } 2570 2571 static int __ext4_journalled_writepage(struct page *page, 2572 unsigned int len) 2573 { 2574 struct address_space *mapping = page->mapping; 2575 struct inode *inode = mapping->host; 2576 struct buffer_head *page_bufs; 2577 handle_t *handle = NULL; 2578 int ret = 0; 2579 int err; 2580 2581 page_bufs = page_buffers(page); 2582 BUG_ON(!page_bufs); 2583 walk_page_buffers(handle, page_bufs, 0, len, NULL, bget_one); 2584 /* As soon as we unlock the page, it can go away, but we have 2585 * references to buffers so we are safe */ 2586 unlock_page(page); 2587 2588 handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode)); 2589 if (IS_ERR(handle)) { 2590 ret = PTR_ERR(handle); 2591 goto out; 2592 } 2593 2594 ret = walk_page_buffers(handle, page_bufs, 0, len, NULL, 2595 do_journal_get_write_access); 2596 2597 err = walk_page_buffers(handle, page_bufs, 0, len, NULL, 2598 write_end_fn); 2599 if (ret == 0) 2600 ret = err; 2601 err = ext4_journal_stop(handle); 2602 if (!ret) 2603 ret = err; 2604 2605 walk_page_buffers(handle, page_bufs, 0, len, NULL, bput_one); 2606 EXT4_I(inode)->i_state |= EXT4_STATE_JDATA; 2607 out: 2608 return ret; 2609 } 2610 2611 /* 2612 * Note that we don't need to start a transaction unless we're journaling data 2613 * because we should have holes filled from ext4_page_mkwrite(). We even don't 2614 * need to file the inode to the transaction's list in ordered mode because if 2615 * we are writing back data added by write(), the inode is already there and if 2616 * we are writing back data modified via mmap(), noone guarantees in which 2617 * transaction the data will hit the disk. In case we are journaling data, we 2618 * cannot start transaction directly because transaction start ranks above page 2619 * lock so we have to do some magic. 2620 * 2621 * This function can get called via... 2622 * - ext4_da_writepages after taking page lock (have journal handle) 2623 * - journal_submit_inode_data_buffers (no journal handle) 2624 * - shrink_page_list via pdflush (no journal handle) 2625 * - grab_page_cache when doing write_begin (have journal handle) 2626 * 2627 * We don't do any block allocation in this function. If we have page with 2628 * multiple blocks we need to write those buffer_heads that are mapped. This 2629 * is important for mmaped based write. So if we do with blocksize 1K 2630 * truncate(f, 1024); 2631 * a = mmap(f, 0, 4096); 2632 * a[0] = 'a'; 2633 * truncate(f, 4096); 2634 * we have in the page first buffer_head mapped via page_mkwrite call back 2635 * but other bufer_heads would be unmapped but dirty(dirty done via the 2636 * do_wp_page). So writepage should write the first block. If we modify 2637 * the mmap area beyond 1024 we will again get a page_fault and the 2638 * page_mkwrite callback will do the block allocation and mark the 2639 * buffer_heads mapped. 2640 * 2641 * We redirty the page if we have any buffer_heads that is either delay or 2642 * unwritten in the page. 2643 * 2644 * We can get recursively called as show below. 2645 * 2646 * ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() -> 2647 * ext4_writepage() 2648 * 2649 * But since we don't do any block allocation we should not deadlock. 2650 * Page also have the dirty flag cleared so we don't get recurive page_lock. 2651 */ 2652 static int ext4_writepage(struct page *page, 2653 struct writeback_control *wbc) 2654 { 2655 int ret = 0; 2656 loff_t size; 2657 unsigned int len; 2658 struct buffer_head *page_bufs; 2659 struct inode *inode = page->mapping->host; 2660 2661 trace_ext4_writepage(inode, page); 2662 size = i_size_read(inode); 2663 if (page->index == size >> PAGE_CACHE_SHIFT) 2664 len = size & ~PAGE_CACHE_MASK; 2665 else 2666 len = PAGE_CACHE_SIZE; 2667 2668 if (page_has_buffers(page)) { 2669 page_bufs = page_buffers(page); 2670 if (walk_page_buffers(NULL, page_bufs, 0, len, NULL, 2671 ext4_bh_delay_or_unwritten)) { 2672 /* 2673 * We don't want to do block allocation 2674 * So redirty the page and return 2675 * We may reach here when we do a journal commit 2676 * via journal_submit_inode_data_buffers. 2677 * If we don't have mapping block we just ignore 2678 * them. We can also reach here via shrink_page_list 2679 */ 2680 redirty_page_for_writepage(wbc, page); 2681 unlock_page(page); 2682 return 0; 2683 } 2684 } else { 2685 /* 2686 * The test for page_has_buffers() is subtle: 2687 * We know the page is dirty but it lost buffers. That means 2688 * that at some moment in time after write_begin()/write_end() 2689 * has been called all buffers have been clean and thus they 2690 * must have been written at least once. So they are all 2691 * mapped and we can happily proceed with mapping them 2692 * and writing the page. 2693 * 2694 * Try to initialize the buffer_heads and check whether 2695 * all are mapped and non delay. We don't want to 2696 * do block allocation here. 2697 */ 2698 ret = block_prepare_write(page, 0, len, 2699 noalloc_get_block_write); 2700 if (!ret) { 2701 page_bufs = page_buffers(page); 2702 /* check whether all are mapped and non delay */ 2703 if (walk_page_buffers(NULL, page_bufs, 0, len, NULL, 2704 ext4_bh_delay_or_unwritten)) { 2705 redirty_page_for_writepage(wbc, page); 2706 unlock_page(page); 2707 return 0; 2708 } 2709 } else { 2710 /* 2711 * We can't do block allocation here 2712 * so just redity the page and unlock 2713 * and return 2714 */ 2715 redirty_page_for_writepage(wbc, page); 2716 unlock_page(page); 2717 return 0; 2718 } 2719 /* now mark the buffer_heads as dirty and uptodate */ 2720 block_commit_write(page, 0, len); 2721 } 2722 2723 if (PageChecked(page) && ext4_should_journal_data(inode)) { 2724 /* 2725 * It's mmapped pagecache. Add buffers and journal it. There 2726 * doesn't seem much point in redirtying the page here. 2727 */ 2728 ClearPageChecked(page); 2729 return __ext4_journalled_writepage(page, len); 2730 } 2731 2732 if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode)) 2733 ret = nobh_writepage(page, noalloc_get_block_write, wbc); 2734 else 2735 ret = block_write_full_page(page, noalloc_get_block_write, 2736 wbc); 2737 2738 return ret; 2739 } 2740 2741 /* 2742 * This is called via ext4_da_writepages() to 2743 * calulate the total number of credits to reserve to fit 2744 * a single extent allocation into a single transaction, 2745 * ext4_da_writpeages() will loop calling this before 2746 * the block allocation. 2747 */ 2748 2749 static int ext4_da_writepages_trans_blocks(struct inode *inode) 2750 { 2751 int max_blocks = EXT4_I(inode)->i_reserved_data_blocks; 2752 2753 /* 2754 * With non-extent format the journal credit needed to 2755 * insert nrblocks contiguous block is dependent on 2756 * number of contiguous block. So we will limit 2757 * number of contiguous block to a sane value 2758 */ 2759 if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) && 2760 (max_blocks > EXT4_MAX_TRANS_DATA)) 2761 max_blocks = EXT4_MAX_TRANS_DATA; 2762 2763 return ext4_chunk_trans_blocks(inode, max_blocks); 2764 } 2765 2766 static int ext4_da_writepages(struct address_space *mapping, 2767 struct writeback_control *wbc) 2768 { 2769 pgoff_t index; 2770 int range_whole = 0; 2771 handle_t *handle = NULL; 2772 struct mpage_da_data mpd; 2773 struct inode *inode = mapping->host; 2774 int no_nrwrite_index_update; 2775 int pages_written = 0; 2776 long pages_skipped; 2777 unsigned int max_pages; 2778 int range_cyclic, cycled = 1, io_done = 0; 2779 int needed_blocks, ret = 0; 2780 long desired_nr_to_write, nr_to_writebump = 0; 2781 loff_t range_start = wbc->range_start; 2782 struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb); 2783 2784 trace_ext4_da_writepages(inode, wbc); 2785 2786 /* 2787 * No pages to write? This is mainly a kludge to avoid starting 2788 * a transaction for special inodes like journal inode on last iput() 2789 * because that could violate lock ordering on umount 2790 */ 2791 if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) 2792 return 0; 2793 2794 /* 2795 * If the filesystem has aborted, it is read-only, so return 2796 * right away instead of dumping stack traces later on that 2797 * will obscure the real source of the problem. We test 2798 * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because 2799 * the latter could be true if the filesystem is mounted 2800 * read-only, and in that case, ext4_da_writepages should 2801 * *never* be called, so if that ever happens, we would want 2802 * the stack trace. 2803 */ 2804 if (unlikely(sbi->s_mount_flags & EXT4_MF_FS_ABORTED)) 2805 return -EROFS; 2806 2807 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) 2808 range_whole = 1; 2809 2810 range_cyclic = wbc->range_cyclic; 2811 if (wbc->range_cyclic) { 2812 index = mapping->writeback_index; 2813 if (index) 2814 cycled = 0; 2815 wbc->range_start = index << PAGE_CACHE_SHIFT; 2816 wbc->range_end = LLONG_MAX; 2817 wbc->range_cyclic = 0; 2818 } else 2819 index = wbc->range_start >> PAGE_CACHE_SHIFT; 2820 2821 /* 2822 * This works around two forms of stupidity. The first is in 2823 * the writeback code, which caps the maximum number of pages 2824 * written to be 1024 pages. This is wrong on multiple 2825 * levels; different architectues have a different page size, 2826 * which changes the maximum amount of data which gets 2827 * written. Secondly, 4 megabytes is way too small. XFS 2828 * forces this value to be 16 megabytes by multiplying 2829 * nr_to_write parameter by four, and then relies on its 2830 * allocator to allocate larger extents to make them 2831 * contiguous. Unfortunately this brings us to the second 2832 * stupidity, which is that ext4's mballoc code only allocates 2833 * at most 2048 blocks. So we force contiguous writes up to 2834 * the number of dirty blocks in the inode, or 2835 * sbi->max_writeback_mb_bump whichever is smaller. 2836 */ 2837 max_pages = sbi->s_max_writeback_mb_bump << (20 - PAGE_CACHE_SHIFT); 2838 if (!range_cyclic && range_whole) 2839 desired_nr_to_write = wbc->nr_to_write * 8; 2840 else 2841 desired_nr_to_write = ext4_num_dirty_pages(inode, index, 2842 max_pages); 2843 if (desired_nr_to_write > max_pages) 2844 desired_nr_to_write = max_pages; 2845 2846 if (wbc->nr_to_write < desired_nr_to_write) { 2847 nr_to_writebump = desired_nr_to_write - wbc->nr_to_write; 2848 wbc->nr_to_write = desired_nr_to_write; 2849 } 2850 2851 mpd.wbc = wbc; 2852 mpd.inode = mapping->host; 2853 2854 /* 2855 * we don't want write_cache_pages to update 2856 * nr_to_write and writeback_index 2857 */ 2858 no_nrwrite_index_update = wbc->no_nrwrite_index_update; 2859 wbc->no_nrwrite_index_update = 1; 2860 pages_skipped = wbc->pages_skipped; 2861 2862 retry: 2863 while (!ret && wbc->nr_to_write > 0) { 2864 2865 /* 2866 * we insert one extent at a time. So we need 2867 * credit needed for single extent allocation. 2868 * journalled mode is currently not supported 2869 * by delalloc 2870 */ 2871 BUG_ON(ext4_should_journal_data(inode)); 2872 needed_blocks = ext4_da_writepages_trans_blocks(inode); 2873 2874 /* start a new transaction*/ 2875 handle = ext4_journal_start(inode, needed_blocks); 2876 if (IS_ERR(handle)) { 2877 ret = PTR_ERR(handle); 2878 ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: " 2879 "%ld pages, ino %lu; err %d\n", __func__, 2880 wbc->nr_to_write, inode->i_ino, ret); 2881 goto out_writepages; 2882 } 2883 2884 /* 2885 * Now call __mpage_da_writepage to find the next 2886 * contiguous region of logical blocks that need 2887 * blocks to be allocated by ext4. We don't actually 2888 * submit the blocks for I/O here, even though 2889 * write_cache_pages thinks it will, and will set the 2890 * pages as clean for write before calling 2891 * __mpage_da_writepage(). 2892 */ 2893 mpd.b_size = 0; 2894 mpd.b_state = 0; 2895 mpd.b_blocknr = 0; 2896 mpd.first_page = 0; 2897 mpd.next_page = 0; 2898 mpd.io_done = 0; 2899 mpd.pages_written = 0; 2900 mpd.retval = 0; 2901 ret = write_cache_pages(mapping, wbc, __mpage_da_writepage, 2902 &mpd); 2903 /* 2904 * If we have a contiguous extent of pages and we 2905 * haven't done the I/O yet, map the blocks and submit 2906 * them for I/O. 2907 */ 2908 if (!mpd.io_done && mpd.next_page != mpd.first_page) { 2909 if (mpage_da_map_blocks(&mpd) == 0) 2910 mpage_da_submit_io(&mpd); 2911 mpd.io_done = 1; 2912 ret = MPAGE_DA_EXTENT_TAIL; 2913 } 2914 trace_ext4_da_write_pages(inode, &mpd); 2915 wbc->nr_to_write -= mpd.pages_written; 2916 2917 ext4_journal_stop(handle); 2918 2919 if ((mpd.retval == -ENOSPC) && sbi->s_journal) { 2920 /* commit the transaction which would 2921 * free blocks released in the transaction 2922 * and try again 2923 */ 2924 jbd2_journal_force_commit_nested(sbi->s_journal); 2925 wbc->pages_skipped = pages_skipped; 2926 ret = 0; 2927 } else if (ret == MPAGE_DA_EXTENT_TAIL) { 2928 /* 2929 * got one extent now try with 2930 * rest of the pages 2931 */ 2932 pages_written += mpd.pages_written; 2933 wbc->pages_skipped = pages_skipped; 2934 ret = 0; 2935 io_done = 1; 2936 } else if (wbc->nr_to_write) 2937 /* 2938 * There is no more writeout needed 2939 * or we requested for a noblocking writeout 2940 * and we found the device congested 2941 */ 2942 break; 2943 } 2944 if (!io_done && !cycled) { 2945 cycled = 1; 2946 index = 0; 2947 wbc->range_start = index << PAGE_CACHE_SHIFT; 2948 wbc->range_end = mapping->writeback_index - 1; 2949 goto retry; 2950 } 2951 if (pages_skipped != wbc->pages_skipped) 2952 ext4_msg(inode->i_sb, KERN_CRIT, 2953 "This should not happen leaving %s " 2954 "with nr_to_write = %ld ret = %d\n", 2955 __func__, wbc->nr_to_write, ret); 2956 2957 /* Update index */ 2958 index += pages_written; 2959 wbc->range_cyclic = range_cyclic; 2960 if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) 2961 /* 2962 * set the writeback_index so that range_cyclic 2963 * mode will write it back later 2964 */ 2965 mapping->writeback_index = index; 2966 2967 out_writepages: 2968 if (!no_nrwrite_index_update) 2969 wbc->no_nrwrite_index_update = 0; 2970 if (wbc->nr_to_write > nr_to_writebump) 2971 wbc->nr_to_write -= nr_to_writebump; 2972 wbc->range_start = range_start; 2973 trace_ext4_da_writepages_result(inode, wbc, ret, pages_written); 2974 return ret; 2975 } 2976 2977 #define FALL_BACK_TO_NONDELALLOC 1 2978 static int ext4_nonda_switch(struct super_block *sb) 2979 { 2980 s64 free_blocks, dirty_blocks; 2981 struct ext4_sb_info *sbi = EXT4_SB(sb); 2982 2983 /* 2984 * switch to non delalloc mode if we are running low 2985 * on free block. The free block accounting via percpu 2986 * counters can get slightly wrong with percpu_counter_batch getting 2987 * accumulated on each CPU without updating global counters 2988 * Delalloc need an accurate free block accounting. So switch 2989 * to non delalloc when we are near to error range. 2990 */ 2991 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter); 2992 dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyblocks_counter); 2993 if (2 * free_blocks < 3 * dirty_blocks || 2994 free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) { 2995 /* 2996 * free block count is less that 150% of dirty blocks 2997 * or free blocks is less that watermark 2998 */ 2999 return 1; 3000 } 3001 return 0; 3002 } 3003 3004 static int ext4_da_write_begin(struct file *file, struct address_space *mapping, 3005 loff_t pos, unsigned len, unsigned flags, 3006 struct page **pagep, void **fsdata) 3007 { 3008 int ret, retries = 0; 3009 struct page *page; 3010 pgoff_t index; 3011 unsigned from, to; 3012 struct inode *inode = mapping->host; 3013 handle_t *handle; 3014 3015 index = pos >> PAGE_CACHE_SHIFT; 3016 from = pos & (PAGE_CACHE_SIZE - 1); 3017 to = from + len; 3018 3019 if (ext4_nonda_switch(inode->i_sb)) { 3020 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC; 3021 return ext4_write_begin(file, mapping, pos, 3022 len, flags, pagep, fsdata); 3023 } 3024 *fsdata = (void *)0; 3025 trace_ext4_da_write_begin(inode, pos, len, flags); 3026 retry: 3027 /* 3028 * With delayed allocation, we don't log the i_disksize update 3029 * if there is delayed block allocation. But we still need 3030 * to journalling the i_disksize update if writes to the end 3031 * of file which has an already mapped buffer. 3032 */ 3033 handle = ext4_journal_start(inode, 1); 3034 if (IS_ERR(handle)) { 3035 ret = PTR_ERR(handle); 3036 goto out; 3037 } 3038 /* We cannot recurse into the filesystem as the transaction is already 3039 * started */ 3040 flags |= AOP_FLAG_NOFS; 3041 3042 page = grab_cache_page_write_begin(mapping, index, flags); 3043 if (!page) { 3044 ext4_journal_stop(handle); 3045 ret = -ENOMEM; 3046 goto out; 3047 } 3048 *pagep = page; 3049 3050 ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata, 3051 ext4_da_get_block_prep); 3052 if (ret < 0) { 3053 unlock_page(page); 3054 ext4_journal_stop(handle); 3055 page_cache_release(page); 3056 /* 3057 * block_write_begin may have instantiated a few blocks 3058 * outside i_size. Trim these off again. Don't need 3059 * i_size_read because we hold i_mutex. 3060 */ 3061 if (pos + len > inode->i_size) 3062 ext4_truncate_failed_write(inode); 3063 } 3064 3065 if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 3066 goto retry; 3067 out: 3068 return ret; 3069 } 3070 3071 /* 3072 * Check if we should update i_disksize 3073 * when write to the end of file but not require block allocation 3074 */ 3075 static int ext4_da_should_update_i_disksize(struct page *page, 3076 unsigned long offset) 3077 { 3078 struct buffer_head *bh; 3079 struct inode *inode = page->mapping->host; 3080 unsigned int idx; 3081 int i; 3082 3083 bh = page_buffers(page); 3084 idx = offset >> inode->i_blkbits; 3085 3086 for (i = 0; i < idx; i++) 3087 bh = bh->b_this_page; 3088 3089 if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh)) 3090 return 0; 3091 return 1; 3092 } 3093 3094 static int ext4_da_write_end(struct file *file, 3095 struct address_space *mapping, 3096 loff_t pos, unsigned len, unsigned copied, 3097 struct page *page, void *fsdata) 3098 { 3099 struct inode *inode = mapping->host; 3100 int ret = 0, ret2; 3101 handle_t *handle = ext4_journal_current_handle(); 3102 loff_t new_i_size; 3103 unsigned long start, end; 3104 int write_mode = (int)(unsigned long)fsdata; 3105 3106 if (write_mode == FALL_BACK_TO_NONDELALLOC) { 3107 if (ext4_should_order_data(inode)) { 3108 return ext4_ordered_write_end(file, mapping, pos, 3109 len, copied, page, fsdata); 3110 } else if (ext4_should_writeback_data(inode)) { 3111 return ext4_writeback_write_end(file, mapping, pos, 3112 len, copied, page, fsdata); 3113 } else { 3114 BUG(); 3115 } 3116 } 3117 3118 trace_ext4_da_write_end(inode, pos, len, copied); 3119 start = pos & (PAGE_CACHE_SIZE - 1); 3120 end = start + copied - 1; 3121 3122 /* 3123 * generic_write_end() will run mark_inode_dirty() if i_size 3124 * changes. So let's piggyback the i_disksize mark_inode_dirty 3125 * into that. 3126 */ 3127 3128 new_i_size = pos + copied; 3129 if (new_i_size > EXT4_I(inode)->i_disksize) { 3130 if (ext4_da_should_update_i_disksize(page, end)) { 3131 down_write(&EXT4_I(inode)->i_data_sem); 3132 if (new_i_size > EXT4_I(inode)->i_disksize) { 3133 /* 3134 * Updating i_disksize when extending file 3135 * without needing block allocation 3136 */ 3137 if (ext4_should_order_data(inode)) 3138 ret = ext4_jbd2_file_inode(handle, 3139 inode); 3140 3141 EXT4_I(inode)->i_disksize = new_i_size; 3142 } 3143 up_write(&EXT4_I(inode)->i_data_sem); 3144 /* We need to mark inode dirty even if 3145 * new_i_size is less that inode->i_size 3146 * bu greater than i_disksize.(hint delalloc) 3147 */ 3148 ext4_mark_inode_dirty(handle, inode); 3149 } 3150 } 3151 ret2 = generic_write_end(file, mapping, pos, len, copied, 3152 page, fsdata); 3153 copied = ret2; 3154 if (ret2 < 0) 3155 ret = ret2; 3156 ret2 = ext4_journal_stop(handle); 3157 if (!ret) 3158 ret = ret2; 3159 3160 return ret ? ret : copied; 3161 } 3162 3163 static void ext4_da_invalidatepage(struct page *page, unsigned long offset) 3164 { 3165 /* 3166 * Drop reserved blocks 3167 */ 3168 BUG_ON(!PageLocked(page)); 3169 if (!page_has_buffers(page)) 3170 goto out; 3171 3172 ext4_da_page_release_reservation(page, offset); 3173 3174 out: 3175 ext4_invalidatepage(page, offset); 3176 3177 return; 3178 } 3179 3180 /* 3181 * Force all delayed allocation blocks to be allocated for a given inode. 3182 */ 3183 int ext4_alloc_da_blocks(struct inode *inode) 3184 { 3185 trace_ext4_alloc_da_blocks(inode); 3186 3187 if (!EXT4_I(inode)->i_reserved_data_blocks && 3188 !EXT4_I(inode)->i_reserved_meta_blocks) 3189 return 0; 3190 3191 /* 3192 * We do something simple for now. The filemap_flush() will 3193 * also start triggering a write of the data blocks, which is 3194 * not strictly speaking necessary (and for users of 3195 * laptop_mode, not even desirable). However, to do otherwise 3196 * would require replicating code paths in: 3197 * 3198 * ext4_da_writepages() -> 3199 * write_cache_pages() ---> (via passed in callback function) 3200 * __mpage_da_writepage() --> 3201 * mpage_add_bh_to_extent() 3202 * mpage_da_map_blocks() 3203 * 3204 * The problem is that write_cache_pages(), located in 3205 * mm/page-writeback.c, marks pages clean in preparation for 3206 * doing I/O, which is not desirable if we're not planning on 3207 * doing I/O at all. 3208 * 3209 * We could call write_cache_pages(), and then redirty all of 3210 * the pages by calling redirty_page_for_writeback() but that 3211 * would be ugly in the extreme. So instead we would need to 3212 * replicate parts of the code in the above functions, 3213 * simplifying them becuase we wouldn't actually intend to 3214 * write out the pages, but rather only collect contiguous 3215 * logical block extents, call the multi-block allocator, and 3216 * then update the buffer heads with the block allocations. 3217 * 3218 * For now, though, we'll cheat by calling filemap_flush(), 3219 * which will map the blocks, and start the I/O, but not 3220 * actually wait for the I/O to complete. 3221 */ 3222 return filemap_flush(inode->i_mapping); 3223 } 3224 3225 /* 3226 * bmap() is special. It gets used by applications such as lilo and by 3227 * the swapper to find the on-disk block of a specific piece of data. 3228 * 3229 * Naturally, this is dangerous if the block concerned is still in the 3230 * journal. If somebody makes a swapfile on an ext4 data-journaling 3231 * filesystem and enables swap, then they may get a nasty shock when the 3232 * data getting swapped to that swapfile suddenly gets overwritten by 3233 * the original zero's written out previously to the journal and 3234 * awaiting writeback in the kernel's buffer cache. 3235 * 3236 * So, if we see any bmap calls here on a modified, data-journaled file, 3237 * take extra steps to flush any blocks which might be in the cache. 3238 */ 3239 static sector_t ext4_bmap(struct address_space *mapping, sector_t block) 3240 { 3241 struct inode *inode = mapping->host; 3242 journal_t *journal; 3243 int err; 3244 3245 if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) && 3246 test_opt(inode->i_sb, DELALLOC)) { 3247 /* 3248 * With delalloc we want to sync the file 3249 * so that we can make sure we allocate 3250 * blocks for file 3251 */ 3252 filemap_write_and_wait(mapping); 3253 } 3254 3255 if (EXT4_JOURNAL(inode) && EXT4_I(inode)->i_state & EXT4_STATE_JDATA) { 3256 /* 3257 * This is a REALLY heavyweight approach, but the use of 3258 * bmap on dirty files is expected to be extremely rare: 3259 * only if we run lilo or swapon on a freshly made file 3260 * do we expect this to happen. 3261 * 3262 * (bmap requires CAP_SYS_RAWIO so this does not 3263 * represent an unprivileged user DOS attack --- we'd be 3264 * in trouble if mortal users could trigger this path at 3265 * will.) 3266 * 3267 * NB. EXT4_STATE_JDATA is not set on files other than 3268 * regular files. If somebody wants to bmap a directory 3269 * or symlink and gets confused because the buffer 3270 * hasn't yet been flushed to disk, they deserve 3271 * everything they get. 3272 */ 3273 3274 EXT4_I(inode)->i_state &= ~EXT4_STATE_JDATA; 3275 journal = EXT4_JOURNAL(inode); 3276 jbd2_journal_lock_updates(journal); 3277 err = jbd2_journal_flush(journal); 3278 jbd2_journal_unlock_updates(journal); 3279 3280 if (err) 3281 return 0; 3282 } 3283 3284 return generic_block_bmap(mapping, block, ext4_get_block); 3285 } 3286 3287 static int ext4_readpage(struct file *file, struct page *page) 3288 { 3289 return mpage_readpage(page, ext4_get_block); 3290 } 3291 3292 static int 3293 ext4_readpages(struct file *file, struct address_space *mapping, 3294 struct list_head *pages, unsigned nr_pages) 3295 { 3296 return mpage_readpages(mapping, pages, nr_pages, ext4_get_block); 3297 } 3298 3299 static void ext4_invalidatepage(struct page *page, unsigned long offset) 3300 { 3301 journal_t *journal = EXT4_JOURNAL(page->mapping->host); 3302 3303 /* 3304 * If it's a full truncate we just forget about the pending dirtying 3305 */ 3306 if (offset == 0) 3307 ClearPageChecked(page); 3308 3309 if (journal) 3310 jbd2_journal_invalidatepage(journal, page, offset); 3311 else 3312 block_invalidatepage(page, offset); 3313 } 3314 3315 static int ext4_releasepage(struct page *page, gfp_t wait) 3316 { 3317 journal_t *journal = EXT4_JOURNAL(page->mapping->host); 3318 3319 WARN_ON(PageChecked(page)); 3320 if (!page_has_buffers(page)) 3321 return 0; 3322 if (journal) 3323 return jbd2_journal_try_to_free_buffers(journal, page, wait); 3324 else 3325 return try_to_free_buffers(page); 3326 } 3327 3328 /* 3329 * O_DIRECT for ext3 (or indirect map) based files 3330 * 3331 * If the O_DIRECT write will extend the file then add this inode to the 3332 * orphan list. So recovery will truncate it back to the original size 3333 * if the machine crashes during the write. 3334 * 3335 * If the O_DIRECT write is intantiating holes inside i_size and the machine 3336 * crashes then stale disk data _may_ be exposed inside the file. But current 3337 * VFS code falls back into buffered path in that case so we are safe. 3338 */ 3339 static ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb, 3340 const struct iovec *iov, loff_t offset, 3341 unsigned long nr_segs) 3342 { 3343 struct file *file = iocb->ki_filp; 3344 struct inode *inode = file->f_mapping->host; 3345 struct ext4_inode_info *ei = EXT4_I(inode); 3346 handle_t *handle; 3347 ssize_t ret; 3348 int orphan = 0; 3349 size_t count = iov_length(iov, nr_segs); 3350 int retries = 0; 3351 3352 if (rw == WRITE) { 3353 loff_t final_size = offset + count; 3354 3355 if (final_size > inode->i_size) { 3356 /* Credits for sb + inode write */ 3357 handle = ext4_journal_start(inode, 2); 3358 if (IS_ERR(handle)) { 3359 ret = PTR_ERR(handle); 3360 goto out; 3361 } 3362 ret = ext4_orphan_add(handle, inode); 3363 if (ret) { 3364 ext4_journal_stop(handle); 3365 goto out; 3366 } 3367 orphan = 1; 3368 ei->i_disksize = inode->i_size; 3369 ext4_journal_stop(handle); 3370 } 3371 } 3372 3373 retry: 3374 ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov, 3375 offset, nr_segs, 3376 ext4_get_block, NULL); 3377 if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries)) 3378 goto retry; 3379 3380 if (orphan) { 3381 int err; 3382 3383 /* Credits for sb + inode write */ 3384 handle = ext4_journal_start(inode, 2); 3385 if (IS_ERR(handle)) { 3386 /* This is really bad luck. We've written the data 3387 * but cannot extend i_size. Bail out and pretend 3388 * the write failed... */ 3389 ret = PTR_ERR(handle); 3390 goto out; 3391 } 3392 if (inode->i_nlink) 3393 ext4_orphan_del(handle, inode); 3394 if (ret > 0) { 3395 loff_t end = offset + ret; 3396 if (end > inode->i_size) { 3397 ei->i_disksize = end; 3398 i_size_write(inode, end); 3399 /* 3400 * We're going to return a positive `ret' 3401 * here due to non-zero-length I/O, so there's 3402 * no way of reporting error returns from 3403 * ext4_mark_inode_dirty() to userspace. So 3404 * ignore it. 3405 */ 3406 ext4_mark_inode_dirty(handle, inode); 3407 } 3408 } 3409 err = ext4_journal_stop(handle); 3410 if (ret == 0) 3411 ret = err; 3412 } 3413 out: 3414 return ret; 3415 } 3416 3417 static int ext4_get_block_dio_write(struct inode *inode, sector_t iblock, 3418 struct buffer_head *bh_result, int create) 3419 { 3420 handle_t *handle = NULL; 3421 int ret = 0; 3422 unsigned max_blocks = bh_result->b_size >> inode->i_blkbits; 3423 int dio_credits; 3424 3425 ext4_debug("ext4_get_block_dio_write: inode %lu, create flag %d\n", 3426 inode->i_ino, create); 3427 /* 3428 * DIO VFS code passes create = 0 flag for write to 3429 * the middle of file. It does this to avoid block 3430 * allocation for holes, to prevent expose stale data 3431 * out when there is parallel buffered read (which does 3432 * not hold the i_mutex lock) while direct IO write has 3433 * not completed. DIO request on holes finally falls back 3434 * to buffered IO for this reason. 3435 * 3436 * For ext4 extent based file, since we support fallocate, 3437 * new allocated extent as uninitialized, for holes, we 3438 * could fallocate blocks for holes, thus parallel 3439 * buffered IO read will zero out the page when read on 3440 * a hole while parallel DIO write to the hole has not completed. 3441 * 3442 * when we come here, we know it's a direct IO write to 3443 * to the middle of file (<i_size) 3444 * so it's safe to override the create flag from VFS. 3445 */ 3446 create = EXT4_GET_BLOCKS_DIO_CREATE_EXT; 3447 3448 if (max_blocks > DIO_MAX_BLOCKS) 3449 max_blocks = DIO_MAX_BLOCKS; 3450 dio_credits = ext4_chunk_trans_blocks(inode, max_blocks); 3451 handle = ext4_journal_start(inode, dio_credits); 3452 if (IS_ERR(handle)) { 3453 ret = PTR_ERR(handle); 3454 goto out; 3455 } 3456 ret = ext4_get_blocks(handle, inode, iblock, max_blocks, bh_result, 3457 create); 3458 if (ret > 0) { 3459 bh_result->b_size = (ret << inode->i_blkbits); 3460 ret = 0; 3461 } 3462 ext4_journal_stop(handle); 3463 out: 3464 return ret; 3465 } 3466 3467 static void ext4_free_io_end(ext4_io_end_t *io) 3468 { 3469 BUG_ON(!io); 3470 iput(io->inode); 3471 kfree(io); 3472 } 3473 static void dump_aio_dio_list(struct inode * inode) 3474 { 3475 #ifdef EXT4_DEBUG 3476 struct list_head *cur, *before, *after; 3477 ext4_io_end_t *io, *io0, *io1; 3478 3479 if (list_empty(&EXT4_I(inode)->i_aio_dio_complete_list)){ 3480 ext4_debug("inode %lu aio dio list is empty\n", inode->i_ino); 3481 return; 3482 } 3483 3484 ext4_debug("Dump inode %lu aio_dio_completed_IO list \n", inode->i_ino); 3485 list_for_each_entry(io, &EXT4_I(inode)->i_aio_dio_complete_list, list){ 3486 cur = &io->list; 3487 before = cur->prev; 3488 io0 = container_of(before, ext4_io_end_t, list); 3489 after = cur->next; 3490 io1 = container_of(after, ext4_io_end_t, list); 3491 3492 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n", 3493 io, inode->i_ino, io0, io1); 3494 } 3495 #endif 3496 } 3497 3498 /* 3499 * check a range of space and convert unwritten extents to written. 3500 */ 3501 static int ext4_end_aio_dio_nolock(ext4_io_end_t *io) 3502 { 3503 struct inode *inode = io->inode; 3504 loff_t offset = io->offset; 3505 size_t size = io->size; 3506 int ret = 0; 3507 3508 ext4_debug("end_aio_dio_onlock: io 0x%p from inode %lu,list->next 0x%p," 3509 "list->prev 0x%p\n", 3510 io, inode->i_ino, io->list.next, io->list.prev); 3511 3512 if (list_empty(&io->list)) 3513 return ret; 3514 3515 if (io->flag != DIO_AIO_UNWRITTEN) 3516 return ret; 3517 3518 if (offset + size <= i_size_read(inode)) 3519 ret = ext4_convert_unwritten_extents(inode, offset, size); 3520 3521 if (ret < 0) { 3522 printk(KERN_EMERG "%s: failed to convert unwritten" 3523 "extents to written extents, error is %d" 3524 " io is still on inode %lu aio dio list\n", 3525 __func__, ret, inode->i_ino); 3526 return ret; 3527 } 3528 3529 /* clear the DIO AIO unwritten flag */ 3530 io->flag = 0; 3531 return ret; 3532 } 3533 /* 3534 * work on completed aio dio IO, to convert unwritten extents to extents 3535 */ 3536 static void ext4_end_aio_dio_work(struct work_struct *work) 3537 { 3538 ext4_io_end_t *io = container_of(work, ext4_io_end_t, work); 3539 struct inode *inode = io->inode; 3540 int ret = 0; 3541 3542 mutex_lock(&inode->i_mutex); 3543 ret = ext4_end_aio_dio_nolock(io); 3544 if (ret >= 0) { 3545 if (!list_empty(&io->list)) 3546 list_del_init(&io->list); 3547 ext4_free_io_end(io); 3548 } 3549 mutex_unlock(&inode->i_mutex); 3550 } 3551 /* 3552 * This function is called from ext4_sync_file(). 3553 * 3554 * When AIO DIO IO is completed, the work to convert unwritten 3555 * extents to written is queued on workqueue but may not get immediately 3556 * scheduled. When fsync is called, we need to ensure the 3557 * conversion is complete before fsync returns. 3558 * The inode keeps track of a list of completed AIO from DIO path 3559 * that might needs to do the conversion. This function walks through 3560 * the list and convert the related unwritten extents to written. 3561 */ 3562 int flush_aio_dio_completed_IO(struct inode *inode) 3563 { 3564 ext4_io_end_t *io; 3565 int ret = 0; 3566 int ret2 = 0; 3567 3568 if (list_empty(&EXT4_I(inode)->i_aio_dio_complete_list)) 3569 return ret; 3570 3571 dump_aio_dio_list(inode); 3572 while (!list_empty(&EXT4_I(inode)->i_aio_dio_complete_list)){ 3573 io = list_entry(EXT4_I(inode)->i_aio_dio_complete_list.next, 3574 ext4_io_end_t, list); 3575 /* 3576 * Calling ext4_end_aio_dio_nolock() to convert completed 3577 * IO to written. 3578 * 3579 * When ext4_sync_file() is called, run_queue() may already 3580 * about to flush the work corresponding to this io structure. 3581 * It will be upset if it founds the io structure related 3582 * to the work-to-be schedule is freed. 3583 * 3584 * Thus we need to keep the io structure still valid here after 3585 * convertion finished. The io structure has a flag to 3586 * avoid double converting from both fsync and background work 3587 * queue work. 3588 */ 3589 ret = ext4_end_aio_dio_nolock(io); 3590 if (ret < 0) 3591 ret2 = ret; 3592 else 3593 list_del_init(&io->list); 3594 } 3595 return (ret2 < 0) ? ret2 : 0; 3596 } 3597 3598 static ext4_io_end_t *ext4_init_io_end (struct inode *inode) 3599 { 3600 ext4_io_end_t *io = NULL; 3601 3602 io = kmalloc(sizeof(*io), GFP_NOFS); 3603 3604 if (io) { 3605 igrab(inode); 3606 io->inode = inode; 3607 io->flag = 0; 3608 io->offset = 0; 3609 io->size = 0; 3610 io->error = 0; 3611 INIT_WORK(&io->work, ext4_end_aio_dio_work); 3612 INIT_LIST_HEAD(&io->list); 3613 } 3614 3615 return io; 3616 } 3617 3618 static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset, 3619 ssize_t size, void *private) 3620 { 3621 ext4_io_end_t *io_end = iocb->private; 3622 struct workqueue_struct *wq; 3623 3624 /* if not async direct IO or dio with 0 bytes write, just return */ 3625 if (!io_end || !size) 3626 return; 3627 3628 ext_debug("ext4_end_io_dio(): io_end 0x%p" 3629 "for inode %lu, iocb 0x%p, offset %llu, size %llu\n", 3630 iocb->private, io_end->inode->i_ino, iocb, offset, 3631 size); 3632 3633 /* if not aio dio with unwritten extents, just free io and return */ 3634 if (io_end->flag != DIO_AIO_UNWRITTEN){ 3635 ext4_free_io_end(io_end); 3636 iocb->private = NULL; 3637 return; 3638 } 3639 3640 io_end->offset = offset; 3641 io_end->size = size; 3642 wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq; 3643 3644 /* queue the work to convert unwritten extents to written */ 3645 queue_work(wq, &io_end->work); 3646 3647 /* Add the io_end to per-inode completed aio dio list*/ 3648 list_add_tail(&io_end->list, 3649 &EXT4_I(io_end->inode)->i_aio_dio_complete_list); 3650 iocb->private = NULL; 3651 } 3652 /* 3653 * For ext4 extent files, ext4 will do direct-io write to holes, 3654 * preallocated extents, and those write extend the file, no need to 3655 * fall back to buffered IO. 3656 * 3657 * For holes, we fallocate those blocks, mark them as unintialized 3658 * If those blocks were preallocated, we mark sure they are splited, but 3659 * still keep the range to write as unintialized. 3660 * 3661 * The unwrritten extents will be converted to written when DIO is completed. 3662 * For async direct IO, since the IO may still pending when return, we 3663 * set up an end_io call back function, which will do the convertion 3664 * when async direct IO completed. 3665 * 3666 * If the O_DIRECT write will extend the file then add this inode to the 3667 * orphan list. So recovery will truncate it back to the original size 3668 * if the machine crashes during the write. 3669 * 3670 */ 3671 static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, 3672 const struct iovec *iov, loff_t offset, 3673 unsigned long nr_segs) 3674 { 3675 struct file *file = iocb->ki_filp; 3676 struct inode *inode = file->f_mapping->host; 3677 ssize_t ret; 3678 size_t count = iov_length(iov, nr_segs); 3679 3680 loff_t final_size = offset + count; 3681 if (rw == WRITE && final_size <= inode->i_size) { 3682 /* 3683 * We could direct write to holes and fallocate. 3684 * 3685 * Allocated blocks to fill the hole are marked as uninitialized 3686 * to prevent paralel buffered read to expose the stale data 3687 * before DIO complete the data IO. 3688 * 3689 * As to previously fallocated extents, ext4 get_block 3690 * will just simply mark the buffer mapped but still 3691 * keep the extents uninitialized. 3692 * 3693 * for non AIO case, we will convert those unwritten extents 3694 * to written after return back from blockdev_direct_IO. 3695 * 3696 * for async DIO, the conversion needs to be defered when 3697 * the IO is completed. The ext4 end_io callback function 3698 * will be called to take care of the conversion work. 3699 * Here for async case, we allocate an io_end structure to 3700 * hook to the iocb. 3701 */ 3702 iocb->private = NULL; 3703 EXT4_I(inode)->cur_aio_dio = NULL; 3704 if (!is_sync_kiocb(iocb)) { 3705 iocb->private = ext4_init_io_end(inode); 3706 if (!iocb->private) 3707 return -ENOMEM; 3708 /* 3709 * we save the io structure for current async 3710 * direct IO, so that later ext4_get_blocks() 3711 * could flag the io structure whether there 3712 * is a unwritten extents needs to be converted 3713 * when IO is completed. 3714 */ 3715 EXT4_I(inode)->cur_aio_dio = iocb->private; 3716 } 3717 3718 ret = blockdev_direct_IO(rw, iocb, inode, 3719 inode->i_sb->s_bdev, iov, 3720 offset, nr_segs, 3721 ext4_get_block_dio_write, 3722 ext4_end_io_dio); 3723 if (iocb->private) 3724 EXT4_I(inode)->cur_aio_dio = NULL; 3725 /* 3726 * The io_end structure takes a reference to the inode, 3727 * that structure needs to be destroyed and the 3728 * reference to the inode need to be dropped, when IO is 3729 * complete, even with 0 byte write, or failed. 3730 * 3731 * In the successful AIO DIO case, the io_end structure will be 3732 * desctroyed and the reference to the inode will be dropped 3733 * after the end_io call back function is called. 3734 * 3735 * In the case there is 0 byte write, or error case, since 3736 * VFS direct IO won't invoke the end_io call back function, 3737 * we need to free the end_io structure here. 3738 */ 3739 if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) { 3740 ext4_free_io_end(iocb->private); 3741 iocb->private = NULL; 3742 } else if (ret > 0 && (EXT4_I(inode)->i_state & 3743 EXT4_STATE_DIO_UNWRITTEN)) { 3744 int err; 3745 /* 3746 * for non AIO case, since the IO is already 3747 * completed, we could do the convertion right here 3748 */ 3749 err = ext4_convert_unwritten_extents(inode, 3750 offset, ret); 3751 if (err < 0) 3752 ret = err; 3753 EXT4_I(inode)->i_state &= ~EXT4_STATE_DIO_UNWRITTEN; 3754 } 3755 return ret; 3756 } 3757 3758 /* for write the the end of file case, we fall back to old way */ 3759 return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs); 3760 } 3761 3762 static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb, 3763 const struct iovec *iov, loff_t offset, 3764 unsigned long nr_segs) 3765 { 3766 struct file *file = iocb->ki_filp; 3767 struct inode *inode = file->f_mapping->host; 3768 3769 if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) 3770 return ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs); 3771 3772 return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs); 3773 } 3774 3775 /* 3776 * Pages can be marked dirty completely asynchronously from ext4's journalling 3777 * activity. By filemap_sync_pte(), try_to_unmap_one(), etc. We cannot do 3778 * much here because ->set_page_dirty is called under VFS locks. The page is 3779 * not necessarily locked. 3780 * 3781 * We cannot just dirty the page and leave attached buffers clean, because the 3782 * buffers' dirty state is "definitive". We cannot just set the buffers dirty 3783 * or jbddirty because all the journalling code will explode. 3784 * 3785 * So what we do is to mark the page "pending dirty" and next time writepage 3786 * is called, propagate that into the buffers appropriately. 3787 */ 3788 static int ext4_journalled_set_page_dirty(struct page *page) 3789 { 3790 SetPageChecked(page); 3791 return __set_page_dirty_nobuffers(page); 3792 } 3793 3794 static const struct address_space_operations ext4_ordered_aops = { 3795 .readpage = ext4_readpage, 3796 .readpages = ext4_readpages, 3797 .writepage = ext4_writepage, 3798 .sync_page = block_sync_page, 3799 .write_begin = ext4_write_begin, 3800 .write_end = ext4_ordered_write_end, 3801 .bmap = ext4_bmap, 3802 .invalidatepage = ext4_invalidatepage, 3803 .releasepage = ext4_releasepage, 3804 .direct_IO = ext4_direct_IO, 3805 .migratepage = buffer_migrate_page, 3806 .is_partially_uptodate = block_is_partially_uptodate, 3807 .error_remove_page = generic_error_remove_page, 3808 }; 3809 3810 static const struct address_space_operations ext4_writeback_aops = { 3811 .readpage = ext4_readpage, 3812 .readpages = ext4_readpages, 3813 .writepage = ext4_writepage, 3814 .sync_page = block_sync_page, 3815 .write_begin = ext4_write_begin, 3816 .write_end = ext4_writeback_write_end, 3817 .bmap = ext4_bmap, 3818 .invalidatepage = ext4_invalidatepage, 3819 .releasepage = ext4_releasepage, 3820 .direct_IO = ext4_direct_IO, 3821 .migratepage = buffer_migrate_page, 3822 .is_partially_uptodate = block_is_partially_uptodate, 3823 .error_remove_page = generic_error_remove_page, 3824 }; 3825 3826 static const struct address_space_operations ext4_journalled_aops = { 3827 .readpage = ext4_readpage, 3828 .readpages = ext4_readpages, 3829 .writepage = ext4_writepage, 3830 .sync_page = block_sync_page, 3831 .write_begin = ext4_write_begin, 3832 .write_end = ext4_journalled_write_end, 3833 .set_page_dirty = ext4_journalled_set_page_dirty, 3834 .bmap = ext4_bmap, 3835 .invalidatepage = ext4_invalidatepage, 3836 .releasepage = ext4_releasepage, 3837 .is_partially_uptodate = block_is_partially_uptodate, 3838 .error_remove_page = generic_error_remove_page, 3839 }; 3840 3841 static const struct address_space_operations ext4_da_aops = { 3842 .readpage = ext4_readpage, 3843 .readpages = ext4_readpages, 3844 .writepage = ext4_writepage, 3845 .writepages = ext4_da_writepages, 3846 .sync_page = block_sync_page, 3847 .write_begin = ext4_da_write_begin, 3848 .write_end = ext4_da_write_end, 3849 .bmap = ext4_bmap, 3850 .invalidatepage = ext4_da_invalidatepage, 3851 .releasepage = ext4_releasepage, 3852 .direct_IO = ext4_direct_IO, 3853 .migratepage = buffer_migrate_page, 3854 .is_partially_uptodate = block_is_partially_uptodate, 3855 .error_remove_page = generic_error_remove_page, 3856 }; 3857 3858 void ext4_set_aops(struct inode *inode) 3859 { 3860 if (ext4_should_order_data(inode) && 3861 test_opt(inode->i_sb, DELALLOC)) 3862 inode->i_mapping->a_ops = &ext4_da_aops; 3863 else if (ext4_should_order_data(inode)) 3864 inode->i_mapping->a_ops = &ext4_ordered_aops; 3865 else if (ext4_should_writeback_data(inode) && 3866 test_opt(inode->i_sb, DELALLOC)) 3867 inode->i_mapping->a_ops = &ext4_da_aops; 3868 else if (ext4_should_writeback_data(inode)) 3869 inode->i_mapping->a_ops = &ext4_writeback_aops; 3870 else 3871 inode->i_mapping->a_ops = &ext4_journalled_aops; 3872 } 3873 3874 /* 3875 * ext4_block_truncate_page() zeroes out a mapping from file offset `from' 3876 * up to the end of the block which corresponds to `from'. 3877 * This required during truncate. We need to physically zero the tail end 3878 * of that block so it doesn't yield old data if the file is later grown. 3879 */ 3880 int ext4_block_truncate_page(handle_t *handle, 3881 struct address_space *mapping, loff_t from) 3882 { 3883 ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT; 3884 unsigned offset = from & (PAGE_CACHE_SIZE-1); 3885 unsigned blocksize, length, pos; 3886 ext4_lblk_t iblock; 3887 struct inode *inode = mapping->host; 3888 struct buffer_head *bh; 3889 struct page *page; 3890 int err = 0; 3891 3892 page = find_or_create_page(mapping, from >> PAGE_CACHE_SHIFT, 3893 mapping_gfp_mask(mapping) & ~__GFP_FS); 3894 if (!page) 3895 return -EINVAL; 3896 3897 blocksize = inode->i_sb->s_blocksize; 3898 length = blocksize - (offset & (blocksize - 1)); 3899 iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits); 3900 3901 /* 3902 * For "nobh" option, we can only work if we don't need to 3903 * read-in the page - otherwise we create buffers to do the IO. 3904 */ 3905 if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) && 3906 ext4_should_writeback_data(inode) && PageUptodate(page)) { 3907 zero_user(page, offset, length); 3908 set_page_dirty(page); 3909 goto unlock; 3910 } 3911 3912 if (!page_has_buffers(page)) 3913 create_empty_buffers(page, blocksize, 0); 3914 3915 /* Find the buffer that contains "offset" */ 3916 bh = page_buffers(page); 3917 pos = blocksize; 3918 while (offset >= pos) { 3919 bh = bh->b_this_page; 3920 iblock++; 3921 pos += blocksize; 3922 } 3923 3924 err = 0; 3925 if (buffer_freed(bh)) { 3926 BUFFER_TRACE(bh, "freed: skip"); 3927 goto unlock; 3928 } 3929 3930 if (!buffer_mapped(bh)) { 3931 BUFFER_TRACE(bh, "unmapped"); 3932 ext4_get_block(inode, iblock, bh, 0); 3933 /* unmapped? It's a hole - nothing to do */ 3934 if (!buffer_mapped(bh)) { 3935 BUFFER_TRACE(bh, "still unmapped"); 3936 goto unlock; 3937 } 3938 } 3939 3940 /* Ok, it's mapped. Make sure it's up-to-date */ 3941 if (PageUptodate(page)) 3942 set_buffer_uptodate(bh); 3943 3944 if (!buffer_uptodate(bh)) { 3945 err = -EIO; 3946 ll_rw_block(READ, 1, &bh); 3947 wait_on_buffer(bh); 3948 /* Uhhuh. Read error. Complain and punt. */ 3949 if (!buffer_uptodate(bh)) 3950 goto unlock; 3951 } 3952 3953 if (ext4_should_journal_data(inode)) { 3954 BUFFER_TRACE(bh, "get write access"); 3955 err = ext4_journal_get_write_access(handle, bh); 3956 if (err) 3957 goto unlock; 3958 } 3959 3960 zero_user(page, offset, length); 3961 3962 BUFFER_TRACE(bh, "zeroed end of block"); 3963 3964 err = 0; 3965 if (ext4_should_journal_data(inode)) { 3966 err = ext4_handle_dirty_metadata(handle, inode, bh); 3967 } else { 3968 if (ext4_should_order_data(inode)) 3969 err = ext4_jbd2_file_inode(handle, inode); 3970 mark_buffer_dirty(bh); 3971 } 3972 3973 unlock: 3974 unlock_page(page); 3975 page_cache_release(page); 3976 return err; 3977 } 3978 3979 /* 3980 * Probably it should be a library function... search for first non-zero word 3981 * or memcmp with zero_page, whatever is better for particular architecture. 3982 * Linus? 3983 */ 3984 static inline int all_zeroes(__le32 *p, __le32 *q) 3985 { 3986 while (p < q) 3987 if (*p++) 3988 return 0; 3989 return 1; 3990 } 3991 3992 /** 3993 * ext4_find_shared - find the indirect blocks for partial truncation. 3994 * @inode: inode in question 3995 * @depth: depth of the affected branch 3996 * @offsets: offsets of pointers in that branch (see ext4_block_to_path) 3997 * @chain: place to store the pointers to partial indirect blocks 3998 * @top: place to the (detached) top of branch 3999 * 4000 * This is a helper function used by ext4_truncate(). 4001 * 4002 * When we do truncate() we may have to clean the ends of several 4003 * indirect blocks but leave the blocks themselves alive. Block is 4004 * partially truncated if some data below the new i_size is refered 4005 * from it (and it is on the path to the first completely truncated 4006 * data block, indeed). We have to free the top of that path along 4007 * with everything to the right of the path. Since no allocation 4008 * past the truncation point is possible until ext4_truncate() 4009 * finishes, we may safely do the latter, but top of branch may 4010 * require special attention - pageout below the truncation point 4011 * might try to populate it. 4012 * 4013 * We atomically detach the top of branch from the tree, store the 4014 * block number of its root in *@top, pointers to buffer_heads of 4015 * partially truncated blocks - in @chain[].bh and pointers to 4016 * their last elements that should not be removed - in 4017 * @chain[].p. Return value is the pointer to last filled element 4018 * of @chain. 4019 * 4020 * The work left to caller to do the actual freeing of subtrees: 4021 * a) free the subtree starting from *@top 4022 * b) free the subtrees whose roots are stored in 4023 * (@chain[i].p+1 .. end of @chain[i].bh->b_data) 4024 * c) free the subtrees growing from the inode past the @chain[0]. 4025 * (no partially truncated stuff there). */ 4026 4027 static Indirect *ext4_find_shared(struct inode *inode, int depth, 4028 ext4_lblk_t offsets[4], Indirect chain[4], 4029 __le32 *top) 4030 { 4031 Indirect *partial, *p; 4032 int k, err; 4033 4034 *top = 0; 4035 /* Make k index the deepest non-null offset + 1 */ 4036 for (k = depth; k > 1 && !offsets[k-1]; k--) 4037 ; 4038 partial = ext4_get_branch(inode, k, offsets, chain, &err); 4039 /* Writer: pointers */ 4040 if (!partial) 4041 partial = chain + k-1; 4042 /* 4043 * If the branch acquired continuation since we've looked at it - 4044 * fine, it should all survive and (new) top doesn't belong to us. 4045 */ 4046 if (!partial->key && *partial->p) 4047 /* Writer: end */ 4048 goto no_top; 4049 for (p = partial; (p > chain) && all_zeroes((__le32 *) p->bh->b_data, p->p); p--) 4050 ; 4051 /* 4052 * OK, we've found the last block that must survive. The rest of our 4053 * branch should be detached before unlocking. However, if that rest 4054 * of branch is all ours and does not grow immediately from the inode 4055 * it's easier to cheat and just decrement partial->p. 4056 */ 4057 if (p == chain + k - 1 && p > chain) { 4058 p->p--; 4059 } else { 4060 *top = *p->p; 4061 /* Nope, don't do this in ext4. Must leave the tree intact */ 4062 #if 0 4063 *p->p = 0; 4064 #endif 4065 } 4066 /* Writer: end */ 4067 4068 while (partial > p) { 4069 brelse(partial->bh); 4070 partial--; 4071 } 4072 no_top: 4073 return partial; 4074 } 4075 4076 /* 4077 * Zero a number of block pointers in either an inode or an indirect block. 4078 * If we restart the transaction we must again get write access to the 4079 * indirect block for further modification. 4080 * 4081 * We release `count' blocks on disk, but (last - first) may be greater 4082 * than `count' because there can be holes in there. 4083 */ 4084 static void ext4_clear_blocks(handle_t *handle, struct inode *inode, 4085 struct buffer_head *bh, 4086 ext4_fsblk_t block_to_free, 4087 unsigned long count, __le32 *first, 4088 __le32 *last) 4089 { 4090 __le32 *p; 4091 int flags = EXT4_FREE_BLOCKS_FORGET; 4092 4093 if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode)) 4094 flags |= EXT4_FREE_BLOCKS_METADATA; 4095 4096 if (try_to_extend_transaction(handle, inode)) { 4097 if (bh) { 4098 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata"); 4099 ext4_handle_dirty_metadata(handle, inode, bh); 4100 } 4101 ext4_mark_inode_dirty(handle, inode); 4102 ext4_truncate_restart_trans(handle, inode, 4103 blocks_for_truncate(inode)); 4104 if (bh) { 4105 BUFFER_TRACE(bh, "retaking write access"); 4106 ext4_journal_get_write_access(handle, bh); 4107 } 4108 } 4109 4110 for (p = first; p < last; p++) 4111 *p = 0; 4112 4113 ext4_free_blocks(handle, inode, 0, block_to_free, count, flags); 4114 } 4115 4116 /** 4117 * ext4_free_data - free a list of data blocks 4118 * @handle: handle for this transaction 4119 * @inode: inode we are dealing with 4120 * @this_bh: indirect buffer_head which contains *@first and *@last 4121 * @first: array of block numbers 4122 * @last: points immediately past the end of array 4123 * 4124 * We are freeing all blocks refered from that array (numbers are stored as 4125 * little-endian 32-bit) and updating @inode->i_blocks appropriately. 4126 * 4127 * We accumulate contiguous runs of blocks to free. Conveniently, if these 4128 * blocks are contiguous then releasing them at one time will only affect one 4129 * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't 4130 * actually use a lot of journal space. 4131 * 4132 * @this_bh will be %NULL if @first and @last point into the inode's direct 4133 * block pointers. 4134 */ 4135 static void ext4_free_data(handle_t *handle, struct inode *inode, 4136 struct buffer_head *this_bh, 4137 __le32 *first, __le32 *last) 4138 { 4139 ext4_fsblk_t block_to_free = 0; /* Starting block # of a run */ 4140 unsigned long count = 0; /* Number of blocks in the run */ 4141 __le32 *block_to_free_p = NULL; /* Pointer into inode/ind 4142 corresponding to 4143 block_to_free */ 4144 ext4_fsblk_t nr; /* Current block # */ 4145 __le32 *p; /* Pointer into inode/ind 4146 for current block */ 4147 int err; 4148 4149 if (this_bh) { /* For indirect block */ 4150 BUFFER_TRACE(this_bh, "get_write_access"); 4151 err = ext4_journal_get_write_access(handle, this_bh); 4152 /* Important: if we can't update the indirect pointers 4153 * to the blocks, we can't free them. */ 4154 if (err) 4155 return; 4156 } 4157 4158 for (p = first; p < last; p++) { 4159 nr = le32_to_cpu(*p); 4160 if (nr) { 4161 /* accumulate blocks to free if they're contiguous */ 4162 if (count == 0) { 4163 block_to_free = nr; 4164 block_to_free_p = p; 4165 count = 1; 4166 } else if (nr == block_to_free + count) { 4167 count++; 4168 } else { 4169 ext4_clear_blocks(handle, inode, this_bh, 4170 block_to_free, 4171 count, block_to_free_p, p); 4172 block_to_free = nr; 4173 block_to_free_p = p; 4174 count = 1; 4175 } 4176 } 4177 } 4178 4179 if (count > 0) 4180 ext4_clear_blocks(handle, inode, this_bh, block_to_free, 4181 count, block_to_free_p, p); 4182 4183 if (this_bh) { 4184 BUFFER_TRACE(this_bh, "call ext4_handle_dirty_metadata"); 4185 4186 /* 4187 * The buffer head should have an attached journal head at this 4188 * point. However, if the data is corrupted and an indirect 4189 * block pointed to itself, it would have been detached when 4190 * the block was cleared. Check for this instead of OOPSing. 4191 */ 4192 if ((EXT4_JOURNAL(inode) == NULL) || bh2jh(this_bh)) 4193 ext4_handle_dirty_metadata(handle, inode, this_bh); 4194 else 4195 ext4_error(inode->i_sb, __func__, 4196 "circular indirect block detected, " 4197 "inode=%lu, block=%llu", 4198 inode->i_ino, 4199 (unsigned long long) this_bh->b_blocknr); 4200 } 4201 } 4202 4203 /** 4204 * ext4_free_branches - free an array of branches 4205 * @handle: JBD handle for this transaction 4206 * @inode: inode we are dealing with 4207 * @parent_bh: the buffer_head which contains *@first and *@last 4208 * @first: array of block numbers 4209 * @last: pointer immediately past the end of array 4210 * @depth: depth of the branches to free 4211 * 4212 * We are freeing all blocks refered from these branches (numbers are 4213 * stored as little-endian 32-bit) and updating @inode->i_blocks 4214 * appropriately. 4215 */ 4216 static void ext4_free_branches(handle_t *handle, struct inode *inode, 4217 struct buffer_head *parent_bh, 4218 __le32 *first, __le32 *last, int depth) 4219 { 4220 ext4_fsblk_t nr; 4221 __le32 *p; 4222 4223 if (ext4_handle_is_aborted(handle)) 4224 return; 4225 4226 if (depth--) { 4227 struct buffer_head *bh; 4228 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb); 4229 p = last; 4230 while (--p >= first) { 4231 nr = le32_to_cpu(*p); 4232 if (!nr) 4233 continue; /* A hole */ 4234 4235 /* Go read the buffer for the next level down */ 4236 bh = sb_bread(inode->i_sb, nr); 4237 4238 /* 4239 * A read failure? Report error and clear slot 4240 * (should be rare). 4241 */ 4242 if (!bh) { 4243 ext4_error(inode->i_sb, "ext4_free_branches", 4244 "Read failure, inode=%lu, block=%llu", 4245 inode->i_ino, nr); 4246 continue; 4247 } 4248 4249 /* This zaps the entire block. Bottom up. */ 4250 BUFFER_TRACE(bh, "free child branches"); 4251 ext4_free_branches(handle, inode, bh, 4252 (__le32 *) bh->b_data, 4253 (__le32 *) bh->b_data + addr_per_block, 4254 depth); 4255 4256 /* 4257 * We've probably journalled the indirect block several 4258 * times during the truncate. But it's no longer 4259 * needed and we now drop it from the transaction via 4260 * jbd2_journal_revoke(). 4261 * 4262 * That's easy if it's exclusively part of this 4263 * transaction. But if it's part of the committing 4264 * transaction then jbd2_journal_forget() will simply 4265 * brelse() it. That means that if the underlying 4266 * block is reallocated in ext4_get_block(), 4267 * unmap_underlying_metadata() will find this block 4268 * and will try to get rid of it. damn, damn. 4269 * 4270 * If this block has already been committed to the 4271 * journal, a revoke record will be written. And 4272 * revoke records must be emitted *before* clearing 4273 * this block's bit in the bitmaps. 4274 */ 4275 ext4_forget(handle, 1, inode, bh, bh->b_blocknr); 4276 4277 /* 4278 * Everything below this this pointer has been 4279 * released. Now let this top-of-subtree go. 4280 * 4281 * We want the freeing of this indirect block to be 4282 * atomic in the journal with the updating of the 4283 * bitmap block which owns it. So make some room in 4284 * the journal. 4285 * 4286 * We zero the parent pointer *after* freeing its 4287 * pointee in the bitmaps, so if extend_transaction() 4288 * for some reason fails to put the bitmap changes and 4289 * the release into the same transaction, recovery 4290 * will merely complain about releasing a free block, 4291 * rather than leaking blocks. 4292 */ 4293 if (ext4_handle_is_aborted(handle)) 4294 return; 4295 if (try_to_extend_transaction(handle, inode)) { 4296 ext4_mark_inode_dirty(handle, inode); 4297 ext4_truncate_restart_trans(handle, inode, 4298 blocks_for_truncate(inode)); 4299 } 4300 4301 ext4_free_blocks(handle, inode, 0, nr, 1, 4302 EXT4_FREE_BLOCKS_METADATA); 4303 4304 if (parent_bh) { 4305 /* 4306 * The block which we have just freed is 4307 * pointed to by an indirect block: journal it 4308 */ 4309 BUFFER_TRACE(parent_bh, "get_write_access"); 4310 if (!ext4_journal_get_write_access(handle, 4311 parent_bh)){ 4312 *p = 0; 4313 BUFFER_TRACE(parent_bh, 4314 "call ext4_handle_dirty_metadata"); 4315 ext4_handle_dirty_metadata(handle, 4316 inode, 4317 parent_bh); 4318 } 4319 } 4320 } 4321 } else { 4322 /* We have reached the bottom of the tree. */ 4323 BUFFER_TRACE(parent_bh, "free data blocks"); 4324 ext4_free_data(handle, inode, parent_bh, first, last); 4325 } 4326 } 4327 4328 int ext4_can_truncate(struct inode *inode) 4329 { 4330 if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) 4331 return 0; 4332 if (S_ISREG(inode->i_mode)) 4333 return 1; 4334 if (S_ISDIR(inode->i_mode)) 4335 return 1; 4336 if (S_ISLNK(inode->i_mode)) 4337 return !ext4_inode_is_fast_symlink(inode); 4338 return 0; 4339 } 4340 4341 /* 4342 * ext4_truncate() 4343 * 4344 * We block out ext4_get_block() block instantiations across the entire 4345 * transaction, and VFS/VM ensures that ext4_truncate() cannot run 4346 * simultaneously on behalf of the same inode. 4347 * 4348 * As we work through the truncate and commmit bits of it to the journal there 4349 * is one core, guiding principle: the file's tree must always be consistent on 4350 * disk. We must be able to restart the truncate after a crash. 4351 * 4352 * The file's tree may be transiently inconsistent in memory (although it 4353 * probably isn't), but whenever we close off and commit a journal transaction, 4354 * the contents of (the filesystem + the journal) must be consistent and 4355 * restartable. It's pretty simple, really: bottom up, right to left (although 4356 * left-to-right works OK too). 4357 * 4358 * Note that at recovery time, journal replay occurs *before* the restart of 4359 * truncate against the orphan inode list. 4360 * 4361 * The committed inode has the new, desired i_size (which is the same as 4362 * i_disksize in this case). After a crash, ext4_orphan_cleanup() will see 4363 * that this inode's truncate did not complete and it will again call 4364 * ext4_truncate() to have another go. So there will be instantiated blocks 4365 * to the right of the truncation point in a crashed ext4 filesystem. But 4366 * that's fine - as long as they are linked from the inode, the post-crash 4367 * ext4_truncate() run will find them and release them. 4368 */ 4369 void ext4_truncate(struct inode *inode) 4370 { 4371 handle_t *handle; 4372 struct ext4_inode_info *ei = EXT4_I(inode); 4373 __le32 *i_data = ei->i_data; 4374 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb); 4375 struct address_space *mapping = inode->i_mapping; 4376 ext4_lblk_t offsets[4]; 4377 Indirect chain[4]; 4378 Indirect *partial; 4379 __le32 nr = 0; 4380 int n; 4381 ext4_lblk_t last_block; 4382 unsigned blocksize = inode->i_sb->s_blocksize; 4383 4384 if (!ext4_can_truncate(inode)) 4385 return; 4386 4387 if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC)) 4388 ei->i_state |= EXT4_STATE_DA_ALLOC_CLOSE; 4389 4390 if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) { 4391 ext4_ext_truncate(inode); 4392 return; 4393 } 4394 4395 handle = start_transaction(inode); 4396 if (IS_ERR(handle)) 4397 return; /* AKPM: return what? */ 4398 4399 last_block = (inode->i_size + blocksize-1) 4400 >> EXT4_BLOCK_SIZE_BITS(inode->i_sb); 4401 4402 if (inode->i_size & (blocksize - 1)) 4403 if (ext4_block_truncate_page(handle, mapping, inode->i_size)) 4404 goto out_stop; 4405 4406 n = ext4_block_to_path(inode, last_block, offsets, NULL); 4407 if (n == 0) 4408 goto out_stop; /* error */ 4409 4410 /* 4411 * OK. This truncate is going to happen. We add the inode to the 4412 * orphan list, so that if this truncate spans multiple transactions, 4413 * and we crash, we will resume the truncate when the filesystem 4414 * recovers. It also marks the inode dirty, to catch the new size. 4415 * 4416 * Implication: the file must always be in a sane, consistent 4417 * truncatable state while each transaction commits. 4418 */ 4419 if (ext4_orphan_add(handle, inode)) 4420 goto out_stop; 4421 4422 /* 4423 * From here we block out all ext4_get_block() callers who want to 4424 * modify the block allocation tree. 4425 */ 4426 down_write(&ei->i_data_sem); 4427 4428 ext4_discard_preallocations(inode); 4429 4430 /* 4431 * The orphan list entry will now protect us from any crash which 4432 * occurs before the truncate completes, so it is now safe to propagate 4433 * the new, shorter inode size (held for now in i_size) into the 4434 * on-disk inode. We do this via i_disksize, which is the value which 4435 * ext4 *really* writes onto the disk inode. 4436 */ 4437 ei->i_disksize = inode->i_size; 4438 4439 if (n == 1) { /* direct blocks */ 4440 ext4_free_data(handle, inode, NULL, i_data+offsets[0], 4441 i_data + EXT4_NDIR_BLOCKS); 4442 goto do_indirects; 4443 } 4444 4445 partial = ext4_find_shared(inode, n, offsets, chain, &nr); 4446 /* Kill the top of shared branch (not detached) */ 4447 if (nr) { 4448 if (partial == chain) { 4449 /* Shared branch grows from the inode */ 4450 ext4_free_branches(handle, inode, NULL, 4451 &nr, &nr+1, (chain+n-1) - partial); 4452 *partial->p = 0; 4453 /* 4454 * We mark the inode dirty prior to restart, 4455 * and prior to stop. No need for it here. 4456 */ 4457 } else { 4458 /* Shared branch grows from an indirect block */ 4459 BUFFER_TRACE(partial->bh, "get_write_access"); 4460 ext4_free_branches(handle, inode, partial->bh, 4461 partial->p, 4462 partial->p+1, (chain+n-1) - partial); 4463 } 4464 } 4465 /* Clear the ends of indirect blocks on the shared branch */ 4466 while (partial > chain) { 4467 ext4_free_branches(handle, inode, partial->bh, partial->p + 1, 4468 (__le32*)partial->bh->b_data+addr_per_block, 4469 (chain+n-1) - partial); 4470 BUFFER_TRACE(partial->bh, "call brelse"); 4471 brelse(partial->bh); 4472 partial--; 4473 } 4474 do_indirects: 4475 /* Kill the remaining (whole) subtrees */ 4476 switch (offsets[0]) { 4477 default: 4478 nr = i_data[EXT4_IND_BLOCK]; 4479 if (nr) { 4480 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1); 4481 i_data[EXT4_IND_BLOCK] = 0; 4482 } 4483 case EXT4_IND_BLOCK: 4484 nr = i_data[EXT4_DIND_BLOCK]; 4485 if (nr) { 4486 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2); 4487 i_data[EXT4_DIND_BLOCK] = 0; 4488 } 4489 case EXT4_DIND_BLOCK: 4490 nr = i_data[EXT4_TIND_BLOCK]; 4491 if (nr) { 4492 ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3); 4493 i_data[EXT4_TIND_BLOCK] = 0; 4494 } 4495 case EXT4_TIND_BLOCK: 4496 ; 4497 } 4498 4499 up_write(&ei->i_data_sem); 4500 inode->i_mtime = inode->i_ctime = ext4_current_time(inode); 4501 ext4_mark_inode_dirty(handle, inode); 4502 4503 /* 4504 * In a multi-transaction truncate, we only make the final transaction 4505 * synchronous 4506 */ 4507 if (IS_SYNC(inode)) 4508 ext4_handle_sync(handle); 4509 out_stop: 4510 /* 4511 * If this was a simple ftruncate(), and the file will remain alive 4512 * then we need to clear up the orphan record which we created above. 4513 * However, if this was a real unlink then we were called by 4514 * ext4_delete_inode(), and we allow that function to clean up the 4515 * orphan info for us. 4516 */ 4517 if (inode->i_nlink) 4518 ext4_orphan_del(handle, inode); 4519 4520 ext4_journal_stop(handle); 4521 } 4522 4523 /* 4524 * ext4_get_inode_loc returns with an extra refcount against the inode's 4525 * underlying buffer_head on success. If 'in_mem' is true, we have all 4526 * data in memory that is needed to recreate the on-disk version of this 4527 * inode. 4528 */ 4529 static int __ext4_get_inode_loc(struct inode *inode, 4530 struct ext4_iloc *iloc, int in_mem) 4531 { 4532 struct ext4_group_desc *gdp; 4533 struct buffer_head *bh; 4534 struct super_block *sb = inode->i_sb; 4535 ext4_fsblk_t block; 4536 int inodes_per_block, inode_offset; 4537 4538 iloc->bh = NULL; 4539 if (!ext4_valid_inum(sb, inode->i_ino)) 4540 return -EIO; 4541 4542 iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb); 4543 gdp = ext4_get_group_desc(sb, iloc->block_group, NULL); 4544 if (!gdp) 4545 return -EIO; 4546 4547 /* 4548 * Figure out the offset within the block group inode table 4549 */ 4550 inodes_per_block = (EXT4_BLOCK_SIZE(sb) / EXT4_INODE_SIZE(sb)); 4551 inode_offset = ((inode->i_ino - 1) % 4552 EXT4_INODES_PER_GROUP(sb)); 4553 block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block); 4554 iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb); 4555 4556 bh = sb_getblk(sb, block); 4557 if (!bh) { 4558 ext4_error(sb, "ext4_get_inode_loc", "unable to read " 4559 "inode block - inode=%lu, block=%llu", 4560 inode->i_ino, block); 4561 return -EIO; 4562 } 4563 if (!buffer_uptodate(bh)) { 4564 lock_buffer(bh); 4565 4566 /* 4567 * If the buffer has the write error flag, we have failed 4568 * to write out another inode in the same block. In this 4569 * case, we don't have to read the block because we may 4570 * read the old inode data successfully. 4571 */ 4572 if (buffer_write_io_error(bh) && !buffer_uptodate(bh)) 4573 set_buffer_uptodate(bh); 4574 4575 if (buffer_uptodate(bh)) { 4576 /* someone brought it uptodate while we waited */ 4577 unlock_buffer(bh); 4578 goto has_buffer; 4579 } 4580 4581 /* 4582 * If we have all information of the inode in memory and this 4583 * is the only valid inode in the block, we need not read the 4584 * block. 4585 */ 4586 if (in_mem) { 4587 struct buffer_head *bitmap_bh; 4588 int i, start; 4589 4590 start = inode_offset & ~(inodes_per_block - 1); 4591 4592 /* Is the inode bitmap in cache? */ 4593 bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp)); 4594 if (!bitmap_bh) 4595 goto make_io; 4596 4597 /* 4598 * If the inode bitmap isn't in cache then the 4599 * optimisation may end up performing two reads instead 4600 * of one, so skip it. 4601 */ 4602 if (!buffer_uptodate(bitmap_bh)) { 4603 brelse(bitmap_bh); 4604 goto make_io; 4605 } 4606 for (i = start; i < start + inodes_per_block; i++) { 4607 if (i == inode_offset) 4608 continue; 4609 if (ext4_test_bit(i, bitmap_bh->b_data)) 4610 break; 4611 } 4612 brelse(bitmap_bh); 4613 if (i == start + inodes_per_block) { 4614 /* all other inodes are free, so skip I/O */ 4615 memset(bh->b_data, 0, bh->b_size); 4616 set_buffer_uptodate(bh); 4617 unlock_buffer(bh); 4618 goto has_buffer; 4619 } 4620 } 4621 4622 make_io: 4623 /* 4624 * If we need to do any I/O, try to pre-readahead extra 4625 * blocks from the inode table. 4626 */ 4627 if (EXT4_SB(sb)->s_inode_readahead_blks) { 4628 ext4_fsblk_t b, end, table; 4629 unsigned num; 4630 4631 table = ext4_inode_table(sb, gdp); 4632 /* s_inode_readahead_blks is always a power of 2 */ 4633 b = block & ~(EXT4_SB(sb)->s_inode_readahead_blks-1); 4634 if (table > b) 4635 b = table; 4636 end = b + EXT4_SB(sb)->s_inode_readahead_blks; 4637 num = EXT4_INODES_PER_GROUP(sb); 4638 if (EXT4_HAS_RO_COMPAT_FEATURE(sb, 4639 EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) 4640 num -= ext4_itable_unused_count(sb, gdp); 4641 table += num / inodes_per_block; 4642 if (end > table) 4643 end = table; 4644 while (b <= end) 4645 sb_breadahead(sb, b++); 4646 } 4647 4648 /* 4649 * There are other valid inodes in the buffer, this inode 4650 * has in-inode xattrs, or we don't have this inode in memory. 4651 * Read the block from disk. 4652 */ 4653 get_bh(bh); 4654 bh->b_end_io = end_buffer_read_sync; 4655 submit_bh(READ_META, bh); 4656 wait_on_buffer(bh); 4657 if (!buffer_uptodate(bh)) { 4658 ext4_error(sb, __func__, 4659 "unable to read inode block - inode=%lu, " 4660 "block=%llu", inode->i_ino, block); 4661 brelse(bh); 4662 return -EIO; 4663 } 4664 } 4665 has_buffer: 4666 iloc->bh = bh; 4667 return 0; 4668 } 4669 4670 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc) 4671 { 4672 /* We have all inode data except xattrs in memory here. */ 4673 return __ext4_get_inode_loc(inode, iloc, 4674 !(EXT4_I(inode)->i_state & EXT4_STATE_XATTR)); 4675 } 4676 4677 void ext4_set_inode_flags(struct inode *inode) 4678 { 4679 unsigned int flags = EXT4_I(inode)->i_flags; 4680 4681 inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC); 4682 if (flags & EXT4_SYNC_FL) 4683 inode->i_flags |= S_SYNC; 4684 if (flags & EXT4_APPEND_FL) 4685 inode->i_flags |= S_APPEND; 4686 if (flags & EXT4_IMMUTABLE_FL) 4687 inode->i_flags |= S_IMMUTABLE; 4688 if (flags & EXT4_NOATIME_FL) 4689 inode->i_flags |= S_NOATIME; 4690 if (flags & EXT4_DIRSYNC_FL) 4691 inode->i_flags |= S_DIRSYNC; 4692 } 4693 4694 /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */ 4695 void ext4_get_inode_flags(struct ext4_inode_info *ei) 4696 { 4697 unsigned int flags = ei->vfs_inode.i_flags; 4698 4699 ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL| 4700 EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|EXT4_DIRSYNC_FL); 4701 if (flags & S_SYNC) 4702 ei->i_flags |= EXT4_SYNC_FL; 4703 if (flags & S_APPEND) 4704 ei->i_flags |= EXT4_APPEND_FL; 4705 if (flags & S_IMMUTABLE) 4706 ei->i_flags |= EXT4_IMMUTABLE_FL; 4707 if (flags & S_NOATIME) 4708 ei->i_flags |= EXT4_NOATIME_FL; 4709 if (flags & S_DIRSYNC) 4710 ei->i_flags |= EXT4_DIRSYNC_FL; 4711 } 4712 4713 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode, 4714 struct ext4_inode_info *ei) 4715 { 4716 blkcnt_t i_blocks ; 4717 struct inode *inode = &(ei->vfs_inode); 4718 struct super_block *sb = inode->i_sb; 4719 4720 if (EXT4_HAS_RO_COMPAT_FEATURE(sb, 4721 EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) { 4722 /* we are using combined 48 bit field */ 4723 i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 | 4724 le32_to_cpu(raw_inode->i_blocks_lo); 4725 if (ei->i_flags & EXT4_HUGE_FILE_FL) { 4726 /* i_blocks represent file system block size */ 4727 return i_blocks << (inode->i_blkbits - 9); 4728 } else { 4729 return i_blocks; 4730 } 4731 } else { 4732 return le32_to_cpu(raw_inode->i_blocks_lo); 4733 } 4734 } 4735 4736 struct inode *ext4_iget(struct super_block *sb, unsigned long ino) 4737 { 4738 struct ext4_iloc iloc; 4739 struct ext4_inode *raw_inode; 4740 struct ext4_inode_info *ei; 4741 struct inode *inode; 4742 journal_t *journal = EXT4_SB(sb)->s_journal; 4743 long ret; 4744 int block; 4745 4746 inode = iget_locked(sb, ino); 4747 if (!inode) 4748 return ERR_PTR(-ENOMEM); 4749 if (!(inode->i_state & I_NEW)) 4750 return inode; 4751 4752 ei = EXT4_I(inode); 4753 iloc.bh = 0; 4754 4755 ret = __ext4_get_inode_loc(inode, &iloc, 0); 4756 if (ret < 0) 4757 goto bad_inode; 4758 raw_inode = ext4_raw_inode(&iloc); 4759 inode->i_mode = le16_to_cpu(raw_inode->i_mode); 4760 inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low); 4761 inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low); 4762 if (!(test_opt(inode->i_sb, NO_UID32))) { 4763 inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16; 4764 inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16; 4765 } 4766 inode->i_nlink = le16_to_cpu(raw_inode->i_links_count); 4767 4768 ei->i_state = 0; 4769 ei->i_dir_start_lookup = 0; 4770 ei->i_dtime = le32_to_cpu(raw_inode->i_dtime); 4771 /* We now have enough fields to check if the inode was active or not. 4772 * This is needed because nfsd might try to access dead inodes 4773 * the test is that same one that e2fsck uses 4774 * NeilBrown 1999oct15 4775 */ 4776 if (inode->i_nlink == 0) { 4777 if (inode->i_mode == 0 || 4778 !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) { 4779 /* this inode is deleted */ 4780 ret = -ESTALE; 4781 goto bad_inode; 4782 } 4783 /* The only unlinked inodes we let through here have 4784 * valid i_mode and are being read by the orphan 4785 * recovery code: that's fine, we're about to complete 4786 * the process of deleting those. */ 4787 } 4788 ei->i_flags = le32_to_cpu(raw_inode->i_flags); 4789 inode->i_blocks = ext4_inode_blocks(raw_inode, ei); 4790 ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo); 4791 if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_64BIT)) 4792 ei->i_file_acl |= 4793 ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32; 4794 inode->i_size = ext4_isize(raw_inode); 4795 ei->i_disksize = inode->i_size; 4796 #ifdef CONFIG_QUOTA 4797 ei->i_reserved_quota = 0; 4798 #endif 4799 inode->i_generation = le32_to_cpu(raw_inode->i_generation); 4800 ei->i_block_group = iloc.block_group; 4801 ei->i_last_alloc_group = ~0; 4802 /* 4803 * NOTE! The in-memory inode i_data array is in little-endian order 4804 * even on big-endian machines: we do NOT byteswap the block numbers! 4805 */ 4806 for (block = 0; block < EXT4_N_BLOCKS; block++) 4807 ei->i_data[block] = raw_inode->i_block[block]; 4808 INIT_LIST_HEAD(&ei->i_orphan); 4809 4810 /* 4811 * Set transaction id's of transactions that have to be committed 4812 * to finish f[data]sync. We set them to currently running transaction 4813 * as we cannot be sure that the inode or some of its metadata isn't 4814 * part of the transaction - the inode could have been reclaimed and 4815 * now it is reread from disk. 4816 */ 4817 if (journal) { 4818 transaction_t *transaction; 4819 tid_t tid; 4820 4821 spin_lock(&journal->j_state_lock); 4822 if (journal->j_running_transaction) 4823 transaction = journal->j_running_transaction; 4824 else 4825 transaction = journal->j_committing_transaction; 4826 if (transaction) 4827 tid = transaction->t_tid; 4828 else 4829 tid = journal->j_commit_sequence; 4830 spin_unlock(&journal->j_state_lock); 4831 ei->i_sync_tid = tid; 4832 ei->i_datasync_tid = tid; 4833 } 4834 4835 if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) { 4836 ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize); 4837 if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize > 4838 EXT4_INODE_SIZE(inode->i_sb)) { 4839 ret = -EIO; 4840 goto bad_inode; 4841 } 4842 if (ei->i_extra_isize == 0) { 4843 /* The extra space is currently unused. Use it. */ 4844 ei->i_extra_isize = sizeof(struct ext4_inode) - 4845 EXT4_GOOD_OLD_INODE_SIZE; 4846 } else { 4847 __le32 *magic = (void *)raw_inode + 4848 EXT4_GOOD_OLD_INODE_SIZE + 4849 ei->i_extra_isize; 4850 if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC)) 4851 ei->i_state |= EXT4_STATE_XATTR; 4852 } 4853 } else 4854 ei->i_extra_isize = 0; 4855 4856 EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode); 4857 EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode); 4858 EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode); 4859 EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode); 4860 4861 inode->i_version = le32_to_cpu(raw_inode->i_disk_version); 4862 if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) { 4863 if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi)) 4864 inode->i_version |= 4865 (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32; 4866 } 4867 4868 ret = 0; 4869 if (ei->i_file_acl && 4870 !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) { 4871 ext4_error(sb, __func__, 4872 "bad extended attribute block %llu in inode #%lu", 4873 ei->i_file_acl, inode->i_ino); 4874 ret = -EIO; 4875 goto bad_inode; 4876 } else if (ei->i_flags & EXT4_EXTENTS_FL) { 4877 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || 4878 (S_ISLNK(inode->i_mode) && 4879 !ext4_inode_is_fast_symlink(inode))) 4880 /* Validate extent which is part of inode */ 4881 ret = ext4_ext_check_inode(inode); 4882 } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) || 4883 (S_ISLNK(inode->i_mode) && 4884 !ext4_inode_is_fast_symlink(inode))) { 4885 /* Validate block references which are part of inode */ 4886 ret = ext4_check_inode_blockref(inode); 4887 } 4888 if (ret) 4889 goto bad_inode; 4890 4891 if (S_ISREG(inode->i_mode)) { 4892 inode->i_op = &ext4_file_inode_operations; 4893 inode->i_fop = &ext4_file_operations; 4894 ext4_set_aops(inode); 4895 } else if (S_ISDIR(inode->i_mode)) { 4896 inode->i_op = &ext4_dir_inode_operations; 4897 inode->i_fop = &ext4_dir_operations; 4898 } else if (S_ISLNK(inode->i_mode)) { 4899 if (ext4_inode_is_fast_symlink(inode)) { 4900 inode->i_op = &ext4_fast_symlink_inode_operations; 4901 nd_terminate_link(ei->i_data, inode->i_size, 4902 sizeof(ei->i_data) - 1); 4903 } else { 4904 inode->i_op = &ext4_symlink_inode_operations; 4905 ext4_set_aops(inode); 4906 } 4907 } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) || 4908 S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) { 4909 inode->i_op = &ext4_special_inode_operations; 4910 if (raw_inode->i_block[0]) 4911 init_special_inode(inode, inode->i_mode, 4912 old_decode_dev(le32_to_cpu(raw_inode->i_block[0]))); 4913 else 4914 init_special_inode(inode, inode->i_mode, 4915 new_decode_dev(le32_to_cpu(raw_inode->i_block[1]))); 4916 } else { 4917 ret = -EIO; 4918 ext4_error(inode->i_sb, __func__, 4919 "bogus i_mode (%o) for inode=%lu", 4920 inode->i_mode, inode->i_ino); 4921 goto bad_inode; 4922 } 4923 brelse(iloc.bh); 4924 ext4_set_inode_flags(inode); 4925 unlock_new_inode(inode); 4926 return inode; 4927 4928 bad_inode: 4929 brelse(iloc.bh); 4930 iget_failed(inode); 4931 return ERR_PTR(ret); 4932 } 4933 4934 static int ext4_inode_blocks_set(handle_t *handle, 4935 struct ext4_inode *raw_inode, 4936 struct ext4_inode_info *ei) 4937 { 4938 struct inode *inode = &(ei->vfs_inode); 4939 u64 i_blocks = inode->i_blocks; 4940 struct super_block *sb = inode->i_sb; 4941 4942 if (i_blocks <= ~0U) { 4943 /* 4944 * i_blocks can be represnted in a 32 bit variable 4945 * as multiple of 512 bytes 4946 */ 4947 raw_inode->i_blocks_lo = cpu_to_le32(i_blocks); 4948 raw_inode->i_blocks_high = 0; 4949 ei->i_flags &= ~EXT4_HUGE_FILE_FL; 4950 return 0; 4951 } 4952 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) 4953 return -EFBIG; 4954 4955 if (i_blocks <= 0xffffffffffffULL) { 4956 /* 4957 * i_blocks can be represented in a 48 bit variable 4958 * as multiple of 512 bytes 4959 */ 4960 raw_inode->i_blocks_lo = cpu_to_le32(i_blocks); 4961 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32); 4962 ei->i_flags &= ~EXT4_HUGE_FILE_FL; 4963 } else { 4964 ei->i_flags |= EXT4_HUGE_FILE_FL; 4965 /* i_block is stored in file system block size */ 4966 i_blocks = i_blocks >> (inode->i_blkbits - 9); 4967 raw_inode->i_blocks_lo = cpu_to_le32(i_blocks); 4968 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32); 4969 } 4970 return 0; 4971 } 4972 4973 /* 4974 * Post the struct inode info into an on-disk inode location in the 4975 * buffer-cache. This gobbles the caller's reference to the 4976 * buffer_head in the inode location struct. 4977 * 4978 * The caller must have write access to iloc->bh. 4979 */ 4980 static int ext4_do_update_inode(handle_t *handle, 4981 struct inode *inode, 4982 struct ext4_iloc *iloc) 4983 { 4984 struct ext4_inode *raw_inode = ext4_raw_inode(iloc); 4985 struct ext4_inode_info *ei = EXT4_I(inode); 4986 struct buffer_head *bh = iloc->bh; 4987 int err = 0, rc, block; 4988 4989 /* For fields not not tracking in the in-memory inode, 4990 * initialise them to zero for new inodes. */ 4991 if (ei->i_state & EXT4_STATE_NEW) 4992 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size); 4993 4994 ext4_get_inode_flags(ei); 4995 raw_inode->i_mode = cpu_to_le16(inode->i_mode); 4996 if (!(test_opt(inode->i_sb, NO_UID32))) { 4997 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid)); 4998 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid)); 4999 /* 5000 * Fix up interoperability with old kernels. Otherwise, old inodes get 5001 * re-used with the upper 16 bits of the uid/gid intact 5002 */ 5003 if (!ei->i_dtime) { 5004 raw_inode->i_uid_high = 5005 cpu_to_le16(high_16_bits(inode->i_uid)); 5006 raw_inode->i_gid_high = 5007 cpu_to_le16(high_16_bits(inode->i_gid)); 5008 } else { 5009 raw_inode->i_uid_high = 0; 5010 raw_inode->i_gid_high = 0; 5011 } 5012 } else { 5013 raw_inode->i_uid_low = 5014 cpu_to_le16(fs_high2lowuid(inode->i_uid)); 5015 raw_inode->i_gid_low = 5016 cpu_to_le16(fs_high2lowgid(inode->i_gid)); 5017 raw_inode->i_uid_high = 0; 5018 raw_inode->i_gid_high = 0; 5019 } 5020 raw_inode->i_links_count = cpu_to_le16(inode->i_nlink); 5021 5022 EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode); 5023 EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode); 5024 EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode); 5025 EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode); 5026 5027 if (ext4_inode_blocks_set(handle, raw_inode, ei)) 5028 goto out_brelse; 5029 raw_inode->i_dtime = cpu_to_le32(ei->i_dtime); 5030 raw_inode->i_flags = cpu_to_le32(ei->i_flags); 5031 if (EXT4_SB(inode->i_sb)->s_es->s_creator_os != 5032 cpu_to_le32(EXT4_OS_HURD)) 5033 raw_inode->i_file_acl_high = 5034 cpu_to_le16(ei->i_file_acl >> 32); 5035 raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl); 5036 ext4_isize_set(raw_inode, ei->i_disksize); 5037 if (ei->i_disksize > 0x7fffffffULL) { 5038 struct super_block *sb = inode->i_sb; 5039 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, 5040 EXT4_FEATURE_RO_COMPAT_LARGE_FILE) || 5041 EXT4_SB(sb)->s_es->s_rev_level == 5042 cpu_to_le32(EXT4_GOOD_OLD_REV)) { 5043 /* If this is the first large file 5044 * created, add a flag to the superblock. 5045 */ 5046 err = ext4_journal_get_write_access(handle, 5047 EXT4_SB(sb)->s_sbh); 5048 if (err) 5049 goto out_brelse; 5050 ext4_update_dynamic_rev(sb); 5051 EXT4_SET_RO_COMPAT_FEATURE(sb, 5052 EXT4_FEATURE_RO_COMPAT_LARGE_FILE); 5053 sb->s_dirt = 1; 5054 ext4_handle_sync(handle); 5055 err = ext4_handle_dirty_metadata(handle, inode, 5056 EXT4_SB(sb)->s_sbh); 5057 } 5058 } 5059 raw_inode->i_generation = cpu_to_le32(inode->i_generation); 5060 if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) { 5061 if (old_valid_dev(inode->i_rdev)) { 5062 raw_inode->i_block[0] = 5063 cpu_to_le32(old_encode_dev(inode->i_rdev)); 5064 raw_inode->i_block[1] = 0; 5065 } else { 5066 raw_inode->i_block[0] = 0; 5067 raw_inode->i_block[1] = 5068 cpu_to_le32(new_encode_dev(inode->i_rdev)); 5069 raw_inode->i_block[2] = 0; 5070 } 5071 } else 5072 for (block = 0; block < EXT4_N_BLOCKS; block++) 5073 raw_inode->i_block[block] = ei->i_data[block]; 5074 5075 raw_inode->i_disk_version = cpu_to_le32(inode->i_version); 5076 if (ei->i_extra_isize) { 5077 if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi)) 5078 raw_inode->i_version_hi = 5079 cpu_to_le32(inode->i_version >> 32); 5080 raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize); 5081 } 5082 5083 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata"); 5084 rc = ext4_handle_dirty_metadata(handle, inode, bh); 5085 if (!err) 5086 err = rc; 5087 ei->i_state &= ~EXT4_STATE_NEW; 5088 5089 ext4_update_inode_fsync_trans(handle, inode, 0); 5090 out_brelse: 5091 brelse(bh); 5092 ext4_std_error(inode->i_sb, err); 5093 return err; 5094 } 5095 5096 /* 5097 * ext4_write_inode() 5098 * 5099 * We are called from a few places: 5100 * 5101 * - Within generic_file_write() for O_SYNC files. 5102 * Here, there will be no transaction running. We wait for any running 5103 * trasnaction to commit. 5104 * 5105 * - Within sys_sync(), kupdate and such. 5106 * We wait on commit, if tol to. 5107 * 5108 * - Within prune_icache() (PF_MEMALLOC == true) 5109 * Here we simply return. We can't afford to block kswapd on the 5110 * journal commit. 5111 * 5112 * In all cases it is actually safe for us to return without doing anything, 5113 * because the inode has been copied into a raw inode buffer in 5114 * ext4_mark_inode_dirty(). This is a correctness thing for O_SYNC and for 5115 * knfsd. 5116 * 5117 * Note that we are absolutely dependent upon all inode dirtiers doing the 5118 * right thing: they *must* call mark_inode_dirty() after dirtying info in 5119 * which we are interested. 5120 * 5121 * It would be a bug for them to not do this. The code: 5122 * 5123 * mark_inode_dirty(inode) 5124 * stuff(); 5125 * inode->i_size = expr; 5126 * 5127 * is in error because a kswapd-driven write_inode() could occur while 5128 * `stuff()' is running, and the new i_size will be lost. Plus the inode 5129 * will no longer be on the superblock's dirty inode list. 5130 */ 5131 int ext4_write_inode(struct inode *inode, int wait) 5132 { 5133 int err; 5134 5135 if (current->flags & PF_MEMALLOC) 5136 return 0; 5137 5138 if (EXT4_SB(inode->i_sb)->s_journal) { 5139 if (ext4_journal_current_handle()) { 5140 jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n"); 5141 dump_stack(); 5142 return -EIO; 5143 } 5144 5145 if (!wait) 5146 return 0; 5147 5148 err = ext4_force_commit(inode->i_sb); 5149 } else { 5150 struct ext4_iloc iloc; 5151 5152 err = ext4_get_inode_loc(inode, &iloc); 5153 if (err) 5154 return err; 5155 if (wait) 5156 sync_dirty_buffer(iloc.bh); 5157 if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) { 5158 ext4_error(inode->i_sb, __func__, 5159 "IO error syncing inode, " 5160 "inode=%lu, block=%llu", 5161 inode->i_ino, 5162 (unsigned long long)iloc.bh->b_blocknr); 5163 err = -EIO; 5164 } 5165 } 5166 return err; 5167 } 5168 5169 /* 5170 * ext4_setattr() 5171 * 5172 * Called from notify_change. 5173 * 5174 * We want to trap VFS attempts to truncate the file as soon as 5175 * possible. In particular, we want to make sure that when the VFS 5176 * shrinks i_size, we put the inode on the orphan list and modify 5177 * i_disksize immediately, so that during the subsequent flushing of 5178 * dirty pages and freeing of disk blocks, we can guarantee that any 5179 * commit will leave the blocks being flushed in an unused state on 5180 * disk. (On recovery, the inode will get truncated and the blocks will 5181 * be freed, so we have a strong guarantee that no future commit will 5182 * leave these blocks visible to the user.) 5183 * 5184 * Another thing we have to assure is that if we are in ordered mode 5185 * and inode is still attached to the committing transaction, we must 5186 * we start writeout of all the dirty pages which are being truncated. 5187 * This way we are sure that all the data written in the previous 5188 * transaction are already on disk (truncate waits for pages under 5189 * writeback). 5190 * 5191 * Called with inode->i_mutex down. 5192 */ 5193 int ext4_setattr(struct dentry *dentry, struct iattr *attr) 5194 { 5195 struct inode *inode = dentry->d_inode; 5196 int error, rc = 0; 5197 const unsigned int ia_valid = attr->ia_valid; 5198 5199 error = inode_change_ok(inode, attr); 5200 if (error) 5201 return error; 5202 5203 if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) || 5204 (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) { 5205 handle_t *handle; 5206 5207 /* (user+group)*(old+new) structure, inode write (sb, 5208 * inode block, ? - but truncate inode update has it) */ 5209 handle = ext4_journal_start(inode, (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb)+ 5210 EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb))+3); 5211 if (IS_ERR(handle)) { 5212 error = PTR_ERR(handle); 5213 goto err_out; 5214 } 5215 error = vfs_dq_transfer(inode, attr) ? -EDQUOT : 0; 5216 if (error) { 5217 ext4_journal_stop(handle); 5218 return error; 5219 } 5220 /* Update corresponding info in inode so that everything is in 5221 * one transaction */ 5222 if (attr->ia_valid & ATTR_UID) 5223 inode->i_uid = attr->ia_uid; 5224 if (attr->ia_valid & ATTR_GID) 5225 inode->i_gid = attr->ia_gid; 5226 error = ext4_mark_inode_dirty(handle, inode); 5227 ext4_journal_stop(handle); 5228 } 5229 5230 if (attr->ia_valid & ATTR_SIZE) { 5231 if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) { 5232 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 5233 5234 if (attr->ia_size > sbi->s_bitmap_maxbytes) { 5235 error = -EFBIG; 5236 goto err_out; 5237 } 5238 } 5239 } 5240 5241 if (S_ISREG(inode->i_mode) && 5242 attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) { 5243 handle_t *handle; 5244 5245 handle = ext4_journal_start(inode, 3); 5246 if (IS_ERR(handle)) { 5247 error = PTR_ERR(handle); 5248 goto err_out; 5249 } 5250 5251 error = ext4_orphan_add(handle, inode); 5252 EXT4_I(inode)->i_disksize = attr->ia_size; 5253 rc = ext4_mark_inode_dirty(handle, inode); 5254 if (!error) 5255 error = rc; 5256 ext4_journal_stop(handle); 5257 5258 if (ext4_should_order_data(inode)) { 5259 error = ext4_begin_ordered_truncate(inode, 5260 attr->ia_size); 5261 if (error) { 5262 /* Do as much error cleanup as possible */ 5263 handle = ext4_journal_start(inode, 3); 5264 if (IS_ERR(handle)) { 5265 ext4_orphan_del(NULL, inode); 5266 goto err_out; 5267 } 5268 ext4_orphan_del(handle, inode); 5269 ext4_journal_stop(handle); 5270 goto err_out; 5271 } 5272 } 5273 } 5274 5275 rc = inode_setattr(inode, attr); 5276 5277 /* If inode_setattr's call to ext4_truncate failed to get a 5278 * transaction handle at all, we need to clean up the in-core 5279 * orphan list manually. */ 5280 if (inode->i_nlink) 5281 ext4_orphan_del(NULL, inode); 5282 5283 if (!rc && (ia_valid & ATTR_MODE)) 5284 rc = ext4_acl_chmod(inode); 5285 5286 err_out: 5287 ext4_std_error(inode->i_sb, error); 5288 if (!error) 5289 error = rc; 5290 return error; 5291 } 5292 5293 int ext4_getattr(struct vfsmount *mnt, struct dentry *dentry, 5294 struct kstat *stat) 5295 { 5296 struct inode *inode; 5297 unsigned long delalloc_blocks; 5298 5299 inode = dentry->d_inode; 5300 generic_fillattr(inode, stat); 5301 5302 /* 5303 * We can't update i_blocks if the block allocation is delayed 5304 * otherwise in the case of system crash before the real block 5305 * allocation is done, we will have i_blocks inconsistent with 5306 * on-disk file blocks. 5307 * We always keep i_blocks updated together with real 5308 * allocation. But to not confuse with user, stat 5309 * will return the blocks that include the delayed allocation 5310 * blocks for this file. 5311 */ 5312 spin_lock(&EXT4_I(inode)->i_block_reservation_lock); 5313 delalloc_blocks = EXT4_I(inode)->i_reserved_data_blocks; 5314 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); 5315 5316 stat->blocks += (delalloc_blocks << inode->i_sb->s_blocksize_bits)>>9; 5317 return 0; 5318 } 5319 5320 static int ext4_indirect_trans_blocks(struct inode *inode, int nrblocks, 5321 int chunk) 5322 { 5323 int indirects; 5324 5325 /* if nrblocks are contiguous */ 5326 if (chunk) { 5327 /* 5328 * With N contiguous data blocks, it need at most 5329 * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) indirect blocks 5330 * 2 dindirect blocks 5331 * 1 tindirect block 5332 */ 5333 indirects = nrblocks / EXT4_ADDR_PER_BLOCK(inode->i_sb); 5334 return indirects + 3; 5335 } 5336 /* 5337 * if nrblocks are not contiguous, worse case, each block touch 5338 * a indirect block, and each indirect block touch a double indirect 5339 * block, plus a triple indirect block 5340 */ 5341 indirects = nrblocks * 2 + 1; 5342 return indirects; 5343 } 5344 5345 static int ext4_index_trans_blocks(struct inode *inode, int nrblocks, int chunk) 5346 { 5347 if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) 5348 return ext4_indirect_trans_blocks(inode, nrblocks, chunk); 5349 return ext4_ext_index_trans_blocks(inode, nrblocks, chunk); 5350 } 5351 5352 /* 5353 * Account for index blocks, block groups bitmaps and block group 5354 * descriptor blocks if modify datablocks and index blocks 5355 * worse case, the indexs blocks spread over different block groups 5356 * 5357 * If datablocks are discontiguous, they are possible to spread over 5358 * different block groups too. If they are contiuguous, with flexbg, 5359 * they could still across block group boundary. 5360 * 5361 * Also account for superblock, inode, quota and xattr blocks 5362 */ 5363 int ext4_meta_trans_blocks(struct inode *inode, int nrblocks, int chunk) 5364 { 5365 ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb); 5366 int gdpblocks; 5367 int idxblocks; 5368 int ret = 0; 5369 5370 /* 5371 * How many index blocks need to touch to modify nrblocks? 5372 * The "Chunk" flag indicating whether the nrblocks is 5373 * physically contiguous on disk 5374 * 5375 * For Direct IO and fallocate, they calls get_block to allocate 5376 * one single extent at a time, so they could set the "Chunk" flag 5377 */ 5378 idxblocks = ext4_index_trans_blocks(inode, nrblocks, chunk); 5379 5380 ret = idxblocks; 5381 5382 /* 5383 * Now let's see how many group bitmaps and group descriptors need 5384 * to account 5385 */ 5386 groups = idxblocks; 5387 if (chunk) 5388 groups += 1; 5389 else 5390 groups += nrblocks; 5391 5392 gdpblocks = groups; 5393 if (groups > ngroups) 5394 groups = ngroups; 5395 if (groups > EXT4_SB(inode->i_sb)->s_gdb_count) 5396 gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count; 5397 5398 /* bitmaps and block group descriptor blocks */ 5399 ret += groups + gdpblocks; 5400 5401 /* Blocks for super block, inode, quota and xattr blocks */ 5402 ret += EXT4_META_TRANS_BLOCKS(inode->i_sb); 5403 5404 return ret; 5405 } 5406 5407 /* 5408 * Calulate the total number of credits to reserve to fit 5409 * the modification of a single pages into a single transaction, 5410 * which may include multiple chunks of block allocations. 5411 * 5412 * This could be called via ext4_write_begin() 5413 * 5414 * We need to consider the worse case, when 5415 * one new block per extent. 5416 */ 5417 int ext4_writepage_trans_blocks(struct inode *inode) 5418 { 5419 int bpp = ext4_journal_blocks_per_page(inode); 5420 int ret; 5421 5422 ret = ext4_meta_trans_blocks(inode, bpp, 0); 5423 5424 /* Account for data blocks for journalled mode */ 5425 if (ext4_should_journal_data(inode)) 5426 ret += bpp; 5427 return ret; 5428 } 5429 5430 /* 5431 * Calculate the journal credits for a chunk of data modification. 5432 * 5433 * This is called from DIO, fallocate or whoever calling 5434 * ext4_get_blocks() to map/allocate a chunk of contiguous disk blocks. 5435 * 5436 * journal buffers for data blocks are not included here, as DIO 5437 * and fallocate do no need to journal data buffers. 5438 */ 5439 int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks) 5440 { 5441 return ext4_meta_trans_blocks(inode, nrblocks, 1); 5442 } 5443 5444 /* 5445 * The caller must have previously called ext4_reserve_inode_write(). 5446 * Give this, we know that the caller already has write access to iloc->bh. 5447 */ 5448 int ext4_mark_iloc_dirty(handle_t *handle, 5449 struct inode *inode, struct ext4_iloc *iloc) 5450 { 5451 int err = 0; 5452 5453 if (test_opt(inode->i_sb, I_VERSION)) 5454 inode_inc_iversion(inode); 5455 5456 /* the do_update_inode consumes one bh->b_count */ 5457 get_bh(iloc->bh); 5458 5459 /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */ 5460 err = ext4_do_update_inode(handle, inode, iloc); 5461 put_bh(iloc->bh); 5462 return err; 5463 } 5464 5465 /* 5466 * On success, We end up with an outstanding reference count against 5467 * iloc->bh. This _must_ be cleaned up later. 5468 */ 5469 5470 int 5471 ext4_reserve_inode_write(handle_t *handle, struct inode *inode, 5472 struct ext4_iloc *iloc) 5473 { 5474 int err; 5475 5476 err = ext4_get_inode_loc(inode, iloc); 5477 if (!err) { 5478 BUFFER_TRACE(iloc->bh, "get_write_access"); 5479 err = ext4_journal_get_write_access(handle, iloc->bh); 5480 if (err) { 5481 brelse(iloc->bh); 5482 iloc->bh = NULL; 5483 } 5484 } 5485 ext4_std_error(inode->i_sb, err); 5486 return err; 5487 } 5488 5489 /* 5490 * Expand an inode by new_extra_isize bytes. 5491 * Returns 0 on success or negative error number on failure. 5492 */ 5493 static int ext4_expand_extra_isize(struct inode *inode, 5494 unsigned int new_extra_isize, 5495 struct ext4_iloc iloc, 5496 handle_t *handle) 5497 { 5498 struct ext4_inode *raw_inode; 5499 struct ext4_xattr_ibody_header *header; 5500 struct ext4_xattr_entry *entry; 5501 5502 if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) 5503 return 0; 5504 5505 raw_inode = ext4_raw_inode(&iloc); 5506 5507 header = IHDR(inode, raw_inode); 5508 entry = IFIRST(header); 5509 5510 /* No extended attributes present */ 5511 if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR) || 5512 header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) { 5513 memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0, 5514 new_extra_isize); 5515 EXT4_I(inode)->i_extra_isize = new_extra_isize; 5516 return 0; 5517 } 5518 5519 /* try to expand with EAs present */ 5520 return ext4_expand_extra_isize_ea(inode, new_extra_isize, 5521 raw_inode, handle); 5522 } 5523 5524 /* 5525 * What we do here is to mark the in-core inode as clean with respect to inode 5526 * dirtiness (it may still be data-dirty). 5527 * This means that the in-core inode may be reaped by prune_icache 5528 * without having to perform any I/O. This is a very good thing, 5529 * because *any* task may call prune_icache - even ones which 5530 * have a transaction open against a different journal. 5531 * 5532 * Is this cheating? Not really. Sure, we haven't written the 5533 * inode out, but prune_icache isn't a user-visible syncing function. 5534 * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync) 5535 * we start and wait on commits. 5536 * 5537 * Is this efficient/effective? Well, we're being nice to the system 5538 * by cleaning up our inodes proactively so they can be reaped 5539 * without I/O. But we are potentially leaving up to five seconds' 5540 * worth of inodes floating about which prune_icache wants us to 5541 * write out. One way to fix that would be to get prune_icache() 5542 * to do a write_super() to free up some memory. It has the desired 5543 * effect. 5544 */ 5545 int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode) 5546 { 5547 struct ext4_iloc iloc; 5548 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); 5549 static unsigned int mnt_count; 5550 int err, ret; 5551 5552 might_sleep(); 5553 err = ext4_reserve_inode_write(handle, inode, &iloc); 5554 if (ext4_handle_valid(handle) && 5555 EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize && 5556 !(EXT4_I(inode)->i_state & EXT4_STATE_NO_EXPAND)) { 5557 /* 5558 * We need extra buffer credits since we may write into EA block 5559 * with this same handle. If journal_extend fails, then it will 5560 * only result in a minor loss of functionality for that inode. 5561 * If this is felt to be critical, then e2fsck should be run to 5562 * force a large enough s_min_extra_isize. 5563 */ 5564 if ((jbd2_journal_extend(handle, 5565 EXT4_DATA_TRANS_BLOCKS(inode->i_sb))) == 0) { 5566 ret = ext4_expand_extra_isize(inode, 5567 sbi->s_want_extra_isize, 5568 iloc, handle); 5569 if (ret) { 5570 EXT4_I(inode)->i_state |= EXT4_STATE_NO_EXPAND; 5571 if (mnt_count != 5572 le16_to_cpu(sbi->s_es->s_mnt_count)) { 5573 ext4_warning(inode->i_sb, __func__, 5574 "Unable to expand inode %lu. Delete" 5575 " some EAs or run e2fsck.", 5576 inode->i_ino); 5577 mnt_count = 5578 le16_to_cpu(sbi->s_es->s_mnt_count); 5579 } 5580 } 5581 } 5582 } 5583 if (!err) 5584 err = ext4_mark_iloc_dirty(handle, inode, &iloc); 5585 return err; 5586 } 5587 5588 /* 5589 * ext4_dirty_inode() is called from __mark_inode_dirty() 5590 * 5591 * We're really interested in the case where a file is being extended. 5592 * i_size has been changed by generic_commit_write() and we thus need 5593 * to include the updated inode in the current transaction. 5594 * 5595 * Also, vfs_dq_alloc_block() will always dirty the inode when blocks 5596 * are allocated to the file. 5597 * 5598 * If the inode is marked synchronous, we don't honour that here - doing 5599 * so would cause a commit on atime updates, which we don't bother doing. 5600 * We handle synchronous inodes at the highest possible level. 5601 */ 5602 void ext4_dirty_inode(struct inode *inode) 5603 { 5604 handle_t *handle; 5605 5606 handle = ext4_journal_start(inode, 2); 5607 if (IS_ERR(handle)) 5608 goto out; 5609 5610 ext4_mark_inode_dirty(handle, inode); 5611 5612 ext4_journal_stop(handle); 5613 out: 5614 return; 5615 } 5616 5617 #if 0 5618 /* 5619 * Bind an inode's backing buffer_head into this transaction, to prevent 5620 * it from being flushed to disk early. Unlike 5621 * ext4_reserve_inode_write, this leaves behind no bh reference and 5622 * returns no iloc structure, so the caller needs to repeat the iloc 5623 * lookup to mark the inode dirty later. 5624 */ 5625 static int ext4_pin_inode(handle_t *handle, struct inode *inode) 5626 { 5627 struct ext4_iloc iloc; 5628 5629 int err = 0; 5630 if (handle) { 5631 err = ext4_get_inode_loc(inode, &iloc); 5632 if (!err) { 5633 BUFFER_TRACE(iloc.bh, "get_write_access"); 5634 err = jbd2_journal_get_write_access(handle, iloc.bh); 5635 if (!err) 5636 err = ext4_handle_dirty_metadata(handle, 5637 inode, 5638 iloc.bh); 5639 brelse(iloc.bh); 5640 } 5641 } 5642 ext4_std_error(inode->i_sb, err); 5643 return err; 5644 } 5645 #endif 5646 5647 int ext4_change_inode_journal_flag(struct inode *inode, int val) 5648 { 5649 journal_t *journal; 5650 handle_t *handle; 5651 int err; 5652 5653 /* 5654 * We have to be very careful here: changing a data block's 5655 * journaling status dynamically is dangerous. If we write a 5656 * data block to the journal, change the status and then delete 5657 * that block, we risk forgetting to revoke the old log record 5658 * from the journal and so a subsequent replay can corrupt data. 5659 * So, first we make sure that the journal is empty and that 5660 * nobody is changing anything. 5661 */ 5662 5663 journal = EXT4_JOURNAL(inode); 5664 if (!journal) 5665 return 0; 5666 if (is_journal_aborted(journal)) 5667 return -EROFS; 5668 5669 jbd2_journal_lock_updates(journal); 5670 jbd2_journal_flush(journal); 5671 5672 /* 5673 * OK, there are no updates running now, and all cached data is 5674 * synced to disk. We are now in a completely consistent state 5675 * which doesn't have anything in the journal, and we know that 5676 * no filesystem updates are running, so it is safe to modify 5677 * the inode's in-core data-journaling state flag now. 5678 */ 5679 5680 if (val) 5681 EXT4_I(inode)->i_flags |= EXT4_JOURNAL_DATA_FL; 5682 else 5683 EXT4_I(inode)->i_flags &= ~EXT4_JOURNAL_DATA_FL; 5684 ext4_set_aops(inode); 5685 5686 jbd2_journal_unlock_updates(journal); 5687 5688 /* Finally we can mark the inode as dirty. */ 5689 5690 handle = ext4_journal_start(inode, 1); 5691 if (IS_ERR(handle)) 5692 return PTR_ERR(handle); 5693 5694 err = ext4_mark_inode_dirty(handle, inode); 5695 ext4_handle_sync(handle); 5696 ext4_journal_stop(handle); 5697 ext4_std_error(inode->i_sb, err); 5698 5699 return err; 5700 } 5701 5702 static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh) 5703 { 5704 return !buffer_mapped(bh); 5705 } 5706 5707 int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) 5708 { 5709 struct page *page = vmf->page; 5710 loff_t size; 5711 unsigned long len; 5712 int ret = -EINVAL; 5713 void *fsdata; 5714 struct file *file = vma->vm_file; 5715 struct inode *inode = file->f_path.dentry->d_inode; 5716 struct address_space *mapping = inode->i_mapping; 5717 5718 /* 5719 * Get i_alloc_sem to stop truncates messing with the inode. We cannot 5720 * get i_mutex because we are already holding mmap_sem. 5721 */ 5722 down_read(&inode->i_alloc_sem); 5723 size = i_size_read(inode); 5724 if (page->mapping != mapping || size <= page_offset(page) 5725 || !PageUptodate(page)) { 5726 /* page got truncated from under us? */ 5727 goto out_unlock; 5728 } 5729 ret = 0; 5730 if (PageMappedToDisk(page)) 5731 goto out_unlock; 5732 5733 if (page->index == size >> PAGE_CACHE_SHIFT) 5734 len = size & ~PAGE_CACHE_MASK; 5735 else 5736 len = PAGE_CACHE_SIZE; 5737 5738 lock_page(page); 5739 /* 5740 * return if we have all the buffers mapped. This avoid 5741 * the need to call write_begin/write_end which does a 5742 * journal_start/journal_stop which can block and take 5743 * long time 5744 */ 5745 if (page_has_buffers(page)) { 5746 if (!walk_page_buffers(NULL, page_buffers(page), 0, len, NULL, 5747 ext4_bh_unmapped)) { 5748 unlock_page(page); 5749 goto out_unlock; 5750 } 5751 } 5752 unlock_page(page); 5753 /* 5754 * OK, we need to fill the hole... Do write_begin write_end 5755 * to do block allocation/reservation.We are not holding 5756 * inode.i__mutex here. That allow * parallel write_begin, 5757 * write_end call. lock_page prevent this from happening 5758 * on the same page though 5759 */ 5760 ret = mapping->a_ops->write_begin(file, mapping, page_offset(page), 5761 len, AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); 5762 if (ret < 0) 5763 goto out_unlock; 5764 ret = mapping->a_ops->write_end(file, mapping, page_offset(page), 5765 len, len, page, fsdata); 5766 if (ret < 0) 5767 goto out_unlock; 5768 ret = 0; 5769 out_unlock: 5770 if (ret) 5771 ret = VM_FAULT_SIGBUS; 5772 up_read(&inode->i_alloc_sem); 5773 return ret; 5774 } 5775