1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* AFS filesystem directory editing 3 * 4 * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/fs.h> 10 #include <linux/namei.h> 11 #include <linux/pagemap.h> 12 #include <linux/iversion.h> 13 #include "internal.h" 14 #include "xdr_fs.h" 15 16 /* 17 * Find a number of contiguous clear bits in a directory block bitmask. 18 * 19 * There are 64 slots, which means we can load the entire bitmap into a 20 * variable. The first bit doesn't count as it corresponds to the block header 21 * slot. nr_slots is between 1 and 9. 22 */ 23 static int afs_find_contig_bits(union afs_xdr_dir_block *block, unsigned int nr_slots) 24 { 25 u64 bitmap; 26 u32 mask; 27 int bit, n; 28 29 bitmap = (u64)block->hdr.bitmap[0] << 0 * 8; 30 bitmap |= (u64)block->hdr.bitmap[1] << 1 * 8; 31 bitmap |= (u64)block->hdr.bitmap[2] << 2 * 8; 32 bitmap |= (u64)block->hdr.bitmap[3] << 3 * 8; 33 bitmap |= (u64)block->hdr.bitmap[4] << 4 * 8; 34 bitmap |= (u64)block->hdr.bitmap[5] << 5 * 8; 35 bitmap |= (u64)block->hdr.bitmap[6] << 6 * 8; 36 bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8; 37 bitmap >>= 1; /* The first entry is metadata */ 38 bit = 1; 39 mask = (1 << nr_slots) - 1; 40 41 do { 42 if (sizeof(unsigned long) == 8) 43 n = ffz(bitmap); 44 else 45 n = ((u32)bitmap) != 0 ? 46 ffz((u32)bitmap) : 47 ffz((u32)(bitmap >> 32)) + 32; 48 bitmap >>= n; 49 bit += n; 50 51 if ((bitmap & mask) == 0) { 52 if (bit > 64 - nr_slots) 53 return -1; 54 return bit; 55 } 56 57 n = __ffs(bitmap); 58 bitmap >>= n; 59 bit += n; 60 } while (bitmap); 61 62 return -1; 63 } 64 65 /* 66 * Set a number of contiguous bits in the directory block bitmap. 67 */ 68 static void afs_set_contig_bits(union afs_xdr_dir_block *block, 69 int bit, unsigned int nr_slots) 70 { 71 u64 mask; 72 73 mask = (1 << nr_slots) - 1; 74 mask <<= bit; 75 76 block->hdr.bitmap[0] |= (u8)(mask >> 0 * 8); 77 block->hdr.bitmap[1] |= (u8)(mask >> 1 * 8); 78 block->hdr.bitmap[2] |= (u8)(mask >> 2 * 8); 79 block->hdr.bitmap[3] |= (u8)(mask >> 3 * 8); 80 block->hdr.bitmap[4] |= (u8)(mask >> 4 * 8); 81 block->hdr.bitmap[5] |= (u8)(mask >> 5 * 8); 82 block->hdr.bitmap[6] |= (u8)(mask >> 6 * 8); 83 block->hdr.bitmap[7] |= (u8)(mask >> 7 * 8); 84 } 85 86 /* 87 * Clear a number of contiguous bits in the directory block bitmap. 88 */ 89 static void afs_clear_contig_bits(union afs_xdr_dir_block *block, 90 int bit, unsigned int nr_slots) 91 { 92 u64 mask; 93 94 mask = (1 << nr_slots) - 1; 95 mask <<= bit; 96 97 block->hdr.bitmap[0] &= ~(u8)(mask >> 0 * 8); 98 block->hdr.bitmap[1] &= ~(u8)(mask >> 1 * 8); 99 block->hdr.bitmap[2] &= ~(u8)(mask >> 2 * 8); 100 block->hdr.bitmap[3] &= ~(u8)(mask >> 3 * 8); 101 block->hdr.bitmap[4] &= ~(u8)(mask >> 4 * 8); 102 block->hdr.bitmap[5] &= ~(u8)(mask >> 5 * 8); 103 block->hdr.bitmap[6] &= ~(u8)(mask >> 6 * 8); 104 block->hdr.bitmap[7] &= ~(u8)(mask >> 7 * 8); 105 } 106 107 /* 108 * Scan a directory block looking for a dirent of the right name. 109 */ 110 static int afs_dir_scan_block(union afs_xdr_dir_block *block, struct qstr *name, 111 unsigned int blocknum) 112 { 113 union afs_xdr_dirent *de; 114 u64 bitmap; 115 int d, len, n; 116 117 _enter(""); 118 119 bitmap = (u64)block->hdr.bitmap[0] << 0 * 8; 120 bitmap |= (u64)block->hdr.bitmap[1] << 1 * 8; 121 bitmap |= (u64)block->hdr.bitmap[2] << 2 * 8; 122 bitmap |= (u64)block->hdr.bitmap[3] << 3 * 8; 123 bitmap |= (u64)block->hdr.bitmap[4] << 4 * 8; 124 bitmap |= (u64)block->hdr.bitmap[5] << 5 * 8; 125 bitmap |= (u64)block->hdr.bitmap[6] << 6 * 8; 126 bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8; 127 128 for (d = (blocknum == 0 ? AFS_DIR_RESV_BLOCKS0 : AFS_DIR_RESV_BLOCKS); 129 d < AFS_DIR_SLOTS_PER_BLOCK; 130 d++) { 131 if (!((bitmap >> d) & 1)) 132 continue; 133 de = &block->dirents[d]; 134 if (de->u.valid != 1) 135 continue; 136 137 /* The block was NUL-terminated by afs_dir_check_page(). */ 138 len = strlen(de->u.name); 139 if (len == name->len && 140 memcmp(de->u.name, name->name, name->len) == 0) 141 return d; 142 143 n = round_up(12 + len + 1 + 4, AFS_DIR_DIRENT_SIZE); 144 n /= AFS_DIR_DIRENT_SIZE; 145 d += n - 1; 146 } 147 148 return -1; 149 } 150 151 /* 152 * Initialise a new directory block. Note that block 0 is special and contains 153 * some extra metadata. 154 */ 155 static void afs_edit_init_block(union afs_xdr_dir_block *meta, 156 union afs_xdr_dir_block *block, int block_num) 157 { 158 memset(block, 0, sizeof(*block)); 159 block->hdr.npages = htons(1); 160 block->hdr.magic = AFS_DIR_MAGIC; 161 block->hdr.bitmap[0] = 1; 162 163 if (block_num == 0) { 164 block->hdr.bitmap[0] = 0xff; 165 block->hdr.bitmap[1] = 0x1f; 166 memset(block->meta.alloc_ctrs, 167 AFS_DIR_SLOTS_PER_BLOCK, 168 sizeof(block->meta.alloc_ctrs)); 169 meta->meta.alloc_ctrs[0] = 170 AFS_DIR_SLOTS_PER_BLOCK - AFS_DIR_RESV_BLOCKS0; 171 } 172 173 if (block_num < AFS_DIR_BLOCKS_WITH_CTR) 174 meta->meta.alloc_ctrs[block_num] = 175 AFS_DIR_SLOTS_PER_BLOCK - AFS_DIR_RESV_BLOCKS; 176 } 177 178 /* 179 * Edit a directory's file data to add a new directory entry. Doing this after 180 * create, mkdir, symlink, link or rename if the data version number is 181 * incremented by exactly one avoids the need to re-download the entire 182 * directory contents. 183 * 184 * The caller must hold the inode locked. 185 */ 186 void afs_edit_dir_add(struct afs_vnode *vnode, 187 struct qstr *name, struct afs_fid *new_fid, 188 enum afs_edit_dir_reason why) 189 { 190 union afs_xdr_dir_block *meta, *block; 191 struct afs_xdr_dir_page *meta_page, *dir_page; 192 union afs_xdr_dirent *de; 193 struct page *page0, *page; 194 unsigned int need_slots, nr_blocks, b; 195 pgoff_t index; 196 loff_t i_size; 197 gfp_t gfp; 198 int slot; 199 200 _enter(",,{%d,%s},", name->len, name->name); 201 202 i_size = i_size_read(&vnode->vfs_inode); 203 if (i_size > AFS_DIR_BLOCK_SIZE * AFS_DIR_MAX_BLOCKS || 204 (i_size & (AFS_DIR_BLOCK_SIZE - 1))) { 205 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 206 return; 207 } 208 209 gfp = vnode->vfs_inode.i_mapping->gfp_mask; 210 page0 = find_or_create_page(vnode->vfs_inode.i_mapping, 0, gfp); 211 if (!page0) { 212 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 213 _leave(" [fgp]"); 214 return; 215 } 216 217 /* Work out how many slots we're going to need. */ 218 need_slots = afs_dir_calc_slots(name->len); 219 220 meta_page = kmap(page0); 221 meta = &meta_page->blocks[0]; 222 if (i_size == 0) 223 goto new_directory; 224 nr_blocks = i_size / AFS_DIR_BLOCK_SIZE; 225 226 /* Find a block that has sufficient slots available. Each VM page 227 * contains two or more directory blocks. 228 */ 229 for (b = 0; b < nr_blocks + 1; b++) { 230 /* If the directory extended into a new page, then we need to 231 * tack a new page on the end. 232 */ 233 index = b / AFS_DIR_BLOCKS_PER_PAGE; 234 if (index == 0) { 235 page = page0; 236 dir_page = meta_page; 237 } else { 238 if (nr_blocks >= AFS_DIR_MAX_BLOCKS) 239 goto error; 240 gfp = vnode->vfs_inode.i_mapping->gfp_mask; 241 page = find_or_create_page(vnode->vfs_inode.i_mapping, 242 index, gfp); 243 if (!page) 244 goto error; 245 if (!PagePrivate(page)) 246 attach_page_private(page, (void *)1); 247 dir_page = kmap(page); 248 } 249 250 /* Abandon the edit if we got a callback break. */ 251 if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags)) 252 goto invalidated; 253 254 block = &dir_page->blocks[b % AFS_DIR_BLOCKS_PER_PAGE]; 255 256 _debug("block %u: %2u %3u %u", 257 b, 258 (b < AFS_DIR_BLOCKS_WITH_CTR) ? meta->meta.alloc_ctrs[b] : 99, 259 ntohs(block->hdr.npages), 260 ntohs(block->hdr.magic)); 261 262 /* Initialise the block if necessary. */ 263 if (b == nr_blocks) { 264 _debug("init %u", b); 265 afs_edit_init_block(meta, block, b); 266 afs_set_i_size(vnode, (b + 1) * AFS_DIR_BLOCK_SIZE); 267 } 268 269 /* Only lower dir pages have a counter in the header. */ 270 if (b >= AFS_DIR_BLOCKS_WITH_CTR || 271 meta->meta.alloc_ctrs[b] >= need_slots) { 272 /* We need to try and find one or more consecutive 273 * slots to hold the entry. 274 */ 275 slot = afs_find_contig_bits(block, need_slots); 276 if (slot >= 0) { 277 _debug("slot %u", slot); 278 goto found_space; 279 } 280 } 281 282 if (page != page0) { 283 unlock_page(page); 284 kunmap(page); 285 put_page(page); 286 } 287 } 288 289 /* There are no spare slots of sufficient size, yet the operation 290 * succeeded. Download the directory again. 291 */ 292 trace_afs_edit_dir(vnode, why, afs_edit_dir_create_nospc, 0, 0, 0, 0, name->name); 293 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 294 goto out_unmap; 295 296 new_directory: 297 afs_edit_init_block(meta, meta, 0); 298 i_size = AFS_DIR_BLOCK_SIZE; 299 afs_set_i_size(vnode, i_size); 300 slot = AFS_DIR_RESV_BLOCKS0; 301 page = page0; 302 block = meta; 303 nr_blocks = 1; 304 b = 0; 305 306 found_space: 307 /* Set the dirent slot. */ 308 trace_afs_edit_dir(vnode, why, afs_edit_dir_create, b, slot, 309 new_fid->vnode, new_fid->unique, name->name); 310 de = &block->dirents[slot]; 311 de->u.valid = 1; 312 de->u.unused[0] = 0; 313 de->u.hash_next = 0; // TODO: Really need to maintain this 314 de->u.vnode = htonl(new_fid->vnode); 315 de->u.unique = htonl(new_fid->unique); 316 memcpy(de->u.name, name->name, name->len + 1); 317 de->u.name[name->len] = 0; 318 319 /* Adjust the bitmap. */ 320 afs_set_contig_bits(block, slot, need_slots); 321 if (page != page0) { 322 unlock_page(page); 323 kunmap(page); 324 put_page(page); 325 } 326 327 /* Adjust the allocation counter. */ 328 if (b < AFS_DIR_BLOCKS_WITH_CTR) 329 meta->meta.alloc_ctrs[b] -= need_slots; 330 331 inode_inc_iversion_raw(&vnode->vfs_inode); 332 afs_stat_v(vnode, n_dir_cr); 333 _debug("Insert %s in %u[%u]", name->name, b, slot); 334 335 out_unmap: 336 unlock_page(page0); 337 kunmap(page0); 338 put_page(page0); 339 _leave(""); 340 return; 341 342 invalidated: 343 trace_afs_edit_dir(vnode, why, afs_edit_dir_create_inval, 0, 0, 0, 0, name->name); 344 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 345 if (page != page0) { 346 kunmap(page); 347 put_page(page); 348 } 349 goto out_unmap; 350 351 error: 352 trace_afs_edit_dir(vnode, why, afs_edit_dir_create_error, 0, 0, 0, 0, name->name); 353 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 354 goto out_unmap; 355 } 356 357 /* 358 * Edit a directory's file data to remove a new directory entry. Doing this 359 * after unlink, rmdir or rename if the data version number is incremented by 360 * exactly one avoids the need to re-download the entire directory contents. 361 * 362 * The caller must hold the inode locked. 363 */ 364 void afs_edit_dir_remove(struct afs_vnode *vnode, 365 struct qstr *name, enum afs_edit_dir_reason why) 366 { 367 struct afs_xdr_dir_page *meta_page, *dir_page; 368 union afs_xdr_dir_block *meta, *block; 369 union afs_xdr_dirent *de; 370 struct page *page0, *page; 371 unsigned int need_slots, nr_blocks, b; 372 pgoff_t index; 373 loff_t i_size; 374 int slot; 375 376 _enter(",,{%d,%s},", name->len, name->name); 377 378 i_size = i_size_read(&vnode->vfs_inode); 379 if (i_size < AFS_DIR_BLOCK_SIZE || 380 i_size > AFS_DIR_BLOCK_SIZE * AFS_DIR_MAX_BLOCKS || 381 (i_size & (AFS_DIR_BLOCK_SIZE - 1))) { 382 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 383 return; 384 } 385 nr_blocks = i_size / AFS_DIR_BLOCK_SIZE; 386 387 page0 = find_lock_page(vnode->vfs_inode.i_mapping, 0); 388 if (!page0) { 389 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 390 _leave(" [fgp]"); 391 return; 392 } 393 394 /* Work out how many slots we're going to discard. */ 395 need_slots = afs_dir_calc_slots(name->len); 396 397 meta_page = kmap(page0); 398 meta = &meta_page->blocks[0]; 399 400 /* Find a page that has sufficient slots available. Each VM page 401 * contains two or more directory blocks. 402 */ 403 for (b = 0; b < nr_blocks; b++) { 404 index = b / AFS_DIR_BLOCKS_PER_PAGE; 405 if (index != 0) { 406 page = find_lock_page(vnode->vfs_inode.i_mapping, index); 407 if (!page) 408 goto error; 409 dir_page = kmap(page); 410 } else { 411 page = page0; 412 dir_page = meta_page; 413 } 414 415 /* Abandon the edit if we got a callback break. */ 416 if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags)) 417 goto invalidated; 418 419 block = &dir_page->blocks[b % AFS_DIR_BLOCKS_PER_PAGE]; 420 421 if (b > AFS_DIR_BLOCKS_WITH_CTR || 422 meta->meta.alloc_ctrs[b] <= AFS_DIR_SLOTS_PER_BLOCK - 1 - need_slots) { 423 slot = afs_dir_scan_block(block, name, b); 424 if (slot >= 0) 425 goto found_dirent; 426 } 427 428 if (page != page0) { 429 unlock_page(page); 430 kunmap(page); 431 put_page(page); 432 } 433 } 434 435 /* Didn't find the dirent to clobber. Download the directory again. */ 436 trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_noent, 437 0, 0, 0, 0, name->name); 438 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 439 goto out_unmap; 440 441 found_dirent: 442 de = &block->dirents[slot]; 443 444 trace_afs_edit_dir(vnode, why, afs_edit_dir_delete, b, slot, 445 ntohl(de->u.vnode), ntohl(de->u.unique), 446 name->name); 447 448 memset(de, 0, sizeof(*de) * need_slots); 449 450 /* Adjust the bitmap. */ 451 afs_clear_contig_bits(block, slot, need_slots); 452 if (page != page0) { 453 unlock_page(page); 454 kunmap(page); 455 put_page(page); 456 } 457 458 /* Adjust the allocation counter. */ 459 if (b < AFS_DIR_BLOCKS_WITH_CTR) 460 meta->meta.alloc_ctrs[b] += need_slots; 461 462 inode_set_iversion_raw(&vnode->vfs_inode, vnode->status.data_version); 463 afs_stat_v(vnode, n_dir_rm); 464 _debug("Remove %s from %u[%u]", name->name, b, slot); 465 466 out_unmap: 467 unlock_page(page0); 468 kunmap(page0); 469 put_page(page0); 470 _leave(""); 471 return; 472 473 invalidated: 474 trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_inval, 475 0, 0, 0, 0, name->name); 476 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 477 if (page != page0) { 478 unlock_page(page); 479 kunmap(page); 480 put_page(page); 481 } 482 goto out_unmap; 483 484 error: 485 trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_error, 486 0, 0, 0, 0, name->name); 487 clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags); 488 goto out_unmap; 489 } 490