1 /* 2 * fs/mpage.c 3 * 4 * Copyright (C) 2002, Linus Torvalds. 5 * 6 * Contains functions related to preparing and submitting BIOs which contain 7 * multiple pagecache pages. 8 * 9 * 15May2002 akpm@zip.com.au 10 * Initial version 11 * 27Jun2002 axboe@suse.de 12 * use bio_add_page() to build bio's just the right size 13 */ 14 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/mm.h> 18 #include <linux/kdev_t.h> 19 #include <linux/bio.h> 20 #include <linux/fs.h> 21 #include <linux/buffer_head.h> 22 #include <linux/blkdev.h> 23 #include <linux/highmem.h> 24 #include <linux/prefetch.h> 25 #include <linux/mpage.h> 26 #include <linux/writeback.h> 27 #include <linux/backing-dev.h> 28 #include <linux/pagevec.h> 29 30 /* 31 * I/O completion handler for multipage BIOs. 32 * 33 * The mpage code never puts partial pages into a BIO (except for end-of-file). 34 * If a page does not map to a contiguous run of blocks then it simply falls 35 * back to block_read_full_page(). 36 * 37 * Why is this? If a page's completion depends on a number of different BIOs 38 * which can complete in any order (or at the same time) then determining the 39 * status of that page is hard. See end_buffer_async_read() for the details. 40 * There is no point in duplicating all that complexity. 41 */ 42 static int mpage_end_io_read(struct bio *bio, unsigned int bytes_done, int err) 43 { 44 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); 45 struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1; 46 47 if (bio->bi_size) 48 return 1; 49 50 do { 51 struct page *page = bvec->bv_page; 52 53 if (--bvec >= bio->bi_io_vec) 54 prefetchw(&bvec->bv_page->flags); 55 56 if (uptodate) { 57 SetPageUptodate(page); 58 } else { 59 ClearPageUptodate(page); 60 SetPageError(page); 61 } 62 unlock_page(page); 63 } while (bvec >= bio->bi_io_vec); 64 bio_put(bio); 65 return 0; 66 } 67 68 static int mpage_end_io_write(struct bio *bio, unsigned int bytes_done, int err) 69 { 70 const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); 71 struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1; 72 73 if (bio->bi_size) 74 return 1; 75 76 do { 77 struct page *page = bvec->bv_page; 78 79 if (--bvec >= bio->bi_io_vec) 80 prefetchw(&bvec->bv_page->flags); 81 82 if (!uptodate){ 83 SetPageError(page); 84 if (page->mapping) 85 set_bit(AS_EIO, &page->mapping->flags); 86 } 87 end_page_writeback(page); 88 } while (bvec >= bio->bi_io_vec); 89 bio_put(bio); 90 return 0; 91 } 92 93 static struct bio *mpage_bio_submit(int rw, struct bio *bio) 94 { 95 bio->bi_end_io = mpage_end_io_read; 96 if (rw == WRITE) 97 bio->bi_end_io = mpage_end_io_write; 98 submit_bio(rw, bio); 99 return NULL; 100 } 101 102 static struct bio * 103 mpage_alloc(struct block_device *bdev, 104 sector_t first_sector, int nr_vecs, 105 gfp_t gfp_flags) 106 { 107 struct bio *bio; 108 109 bio = bio_alloc(gfp_flags, nr_vecs); 110 111 if (bio == NULL && (current->flags & PF_MEMALLOC)) { 112 while (!bio && (nr_vecs /= 2)) 113 bio = bio_alloc(gfp_flags, nr_vecs); 114 } 115 116 if (bio) { 117 bio->bi_bdev = bdev; 118 bio->bi_sector = first_sector; 119 } 120 return bio; 121 } 122 123 /* 124 * support function for mpage_readpages. The fs supplied get_block might 125 * return an up to date buffer. This is used to map that buffer into 126 * the page, which allows readpage to avoid triggering a duplicate call 127 * to get_block. 128 * 129 * The idea is to avoid adding buffers to pages that don't already have 130 * them. So when the buffer is up to date and the page size == block size, 131 * this marks the page up to date instead of adding new buffers. 132 */ 133 static void 134 map_buffer_to_page(struct page *page, struct buffer_head *bh, int page_block) 135 { 136 struct inode *inode = page->mapping->host; 137 struct buffer_head *page_bh, *head; 138 int block = 0; 139 140 if (!page_has_buffers(page)) { 141 /* 142 * don't make any buffers if there is only one buffer on 143 * the page and the page just needs to be set up to date 144 */ 145 if (inode->i_blkbits == PAGE_CACHE_SHIFT && 146 buffer_uptodate(bh)) { 147 SetPageUptodate(page); 148 return; 149 } 150 create_empty_buffers(page, 1 << inode->i_blkbits, 0); 151 } 152 head = page_buffers(page); 153 page_bh = head; 154 do { 155 if (block == page_block) { 156 page_bh->b_state = bh->b_state; 157 page_bh->b_bdev = bh->b_bdev; 158 page_bh->b_blocknr = bh->b_blocknr; 159 break; 160 } 161 page_bh = page_bh->b_this_page; 162 block++; 163 } while (page_bh != head); 164 } 165 166 static struct bio * 167 do_mpage_readpage(struct bio *bio, struct page *page, unsigned nr_pages, 168 sector_t *last_block_in_bio, get_block_t get_block) 169 { 170 struct inode *inode = page->mapping->host; 171 const unsigned blkbits = inode->i_blkbits; 172 const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits; 173 const unsigned blocksize = 1 << blkbits; 174 sector_t block_in_file; 175 sector_t last_block; 176 sector_t blocks[MAX_BUF_PER_PAGE]; 177 unsigned page_block; 178 unsigned first_hole = blocks_per_page; 179 struct block_device *bdev = NULL; 180 struct buffer_head bh; 181 int length; 182 int fully_mapped = 1; 183 184 if (page_has_buffers(page)) 185 goto confused; 186 187 block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits); 188 last_block = (i_size_read(inode) + blocksize - 1) >> blkbits; 189 190 bh.b_page = page; 191 for (page_block = 0; page_block < blocks_per_page; 192 page_block++, block_in_file++) { 193 bh.b_state = 0; 194 if (block_in_file < last_block) { 195 if (get_block(inode, block_in_file, &bh, 0)) 196 goto confused; 197 } 198 199 if (!buffer_mapped(&bh)) { 200 fully_mapped = 0; 201 if (first_hole == blocks_per_page) 202 first_hole = page_block; 203 continue; 204 } 205 206 /* some filesystems will copy data into the page during 207 * the get_block call, in which case we don't want to 208 * read it again. map_buffer_to_page copies the data 209 * we just collected from get_block into the page's buffers 210 * so readpage doesn't have to repeat the get_block call 211 */ 212 if (buffer_uptodate(&bh)) { 213 map_buffer_to_page(page, &bh, page_block); 214 goto confused; 215 } 216 217 if (first_hole != blocks_per_page) 218 goto confused; /* hole -> non-hole */ 219 220 /* Contiguous blocks? */ 221 if (page_block && blocks[page_block-1] != bh.b_blocknr-1) 222 goto confused; 223 blocks[page_block] = bh.b_blocknr; 224 bdev = bh.b_bdev; 225 } 226 227 if (first_hole != blocks_per_page) { 228 char *kaddr = kmap_atomic(page, KM_USER0); 229 memset(kaddr + (first_hole << blkbits), 0, 230 PAGE_CACHE_SIZE - (first_hole << blkbits)); 231 flush_dcache_page(page); 232 kunmap_atomic(kaddr, KM_USER0); 233 if (first_hole == 0) { 234 SetPageUptodate(page); 235 unlock_page(page); 236 goto out; 237 } 238 } else if (fully_mapped) { 239 SetPageMappedToDisk(page); 240 } 241 242 /* 243 * This page will go to BIO. Do we need to send this BIO off first? 244 */ 245 if (bio && (*last_block_in_bio != blocks[0] - 1)) 246 bio = mpage_bio_submit(READ, bio); 247 248 alloc_new: 249 if (bio == NULL) { 250 bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9), 251 min_t(int, nr_pages, bio_get_nr_vecs(bdev)), 252 GFP_KERNEL); 253 if (bio == NULL) 254 goto confused; 255 } 256 257 length = first_hole << blkbits; 258 if (bio_add_page(bio, page, length, 0) < length) { 259 bio = mpage_bio_submit(READ, bio); 260 goto alloc_new; 261 } 262 263 if (buffer_boundary(&bh) || (first_hole != blocks_per_page)) 264 bio = mpage_bio_submit(READ, bio); 265 else 266 *last_block_in_bio = blocks[blocks_per_page - 1]; 267 out: 268 return bio; 269 270 confused: 271 if (bio) 272 bio = mpage_bio_submit(READ, bio); 273 if (!PageUptodate(page)) 274 block_read_full_page(page, get_block); 275 else 276 unlock_page(page); 277 goto out; 278 } 279 280 /** 281 * mpage_readpages - populate an address space with some pages, and 282 * start reads against them. 283 * 284 * @mapping: the address_space 285 * @pages: The address of a list_head which contains the target pages. These 286 * pages have their ->index populated and are otherwise uninitialised. 287 * 288 * The page at @pages->prev has the lowest file offset, and reads should be 289 * issued in @pages->prev to @pages->next order. 290 * 291 * @nr_pages: The number of pages at *@pages 292 * @get_block: The filesystem's block mapper function. 293 * 294 * This function walks the pages and the blocks within each page, building and 295 * emitting large BIOs. 296 * 297 * If anything unusual happens, such as: 298 * 299 * - encountering a page which has buffers 300 * - encountering a page which has a non-hole after a hole 301 * - encountering a page with non-contiguous blocks 302 * 303 * then this code just gives up and calls the buffer_head-based read function. 304 * It does handle a page which has holes at the end - that is a common case: 305 * the end-of-file on blocksize < PAGE_CACHE_SIZE setups. 306 * 307 * BH_Boundary explanation: 308 * 309 * There is a problem. The mpage read code assembles several pages, gets all 310 * their disk mappings, and then submits them all. That's fine, but obtaining 311 * the disk mappings may require I/O. Reads of indirect blocks, for example. 312 * 313 * So an mpage read of the first 16 blocks of an ext2 file will cause I/O to be 314 * submitted in the following order: 315 * 12 0 1 2 3 4 5 6 7 8 9 10 11 13 14 15 16 316 * because the indirect block has to be read to get the mappings of blocks 317 * 13,14,15,16. Obviously, this impacts performance. 318 * 319 * So what we do it to allow the filesystem's get_block() function to set 320 * BH_Boundary when it maps block 11. BH_Boundary says: mapping of the block 321 * after this one will require I/O against a block which is probably close to 322 * this one. So you should push what I/O you have currently accumulated. 323 * 324 * This all causes the disk requests to be issued in the correct order. 325 */ 326 int 327 mpage_readpages(struct address_space *mapping, struct list_head *pages, 328 unsigned nr_pages, get_block_t get_block) 329 { 330 struct bio *bio = NULL; 331 unsigned page_idx; 332 sector_t last_block_in_bio = 0; 333 struct pagevec lru_pvec; 334 335 pagevec_init(&lru_pvec, 0); 336 for (page_idx = 0; page_idx < nr_pages; page_idx++) { 337 struct page *page = list_entry(pages->prev, struct page, lru); 338 339 prefetchw(&page->flags); 340 list_del(&page->lru); 341 if (!add_to_page_cache(page, mapping, 342 page->index, GFP_KERNEL)) { 343 bio = do_mpage_readpage(bio, page, 344 nr_pages - page_idx, 345 &last_block_in_bio, get_block); 346 if (!pagevec_add(&lru_pvec, page)) 347 __pagevec_lru_add(&lru_pvec); 348 } else { 349 page_cache_release(page); 350 } 351 } 352 pagevec_lru_add(&lru_pvec); 353 BUG_ON(!list_empty(pages)); 354 if (bio) 355 mpage_bio_submit(READ, bio); 356 return 0; 357 } 358 EXPORT_SYMBOL(mpage_readpages); 359 360 /* 361 * This isn't called much at all 362 */ 363 int mpage_readpage(struct page *page, get_block_t get_block) 364 { 365 struct bio *bio = NULL; 366 sector_t last_block_in_bio = 0; 367 368 bio = do_mpage_readpage(bio, page, 1, 369 &last_block_in_bio, get_block); 370 if (bio) 371 mpage_bio_submit(READ, bio); 372 return 0; 373 } 374 EXPORT_SYMBOL(mpage_readpage); 375 376 /* 377 * Writing is not so simple. 378 * 379 * If the page has buffers then they will be used for obtaining the disk 380 * mapping. We only support pages which are fully mapped-and-dirty, with a 381 * special case for pages which are unmapped at the end: end-of-file. 382 * 383 * If the page has no buffers (preferred) then the page is mapped here. 384 * 385 * If all blocks are found to be contiguous then the page can go into the 386 * BIO. Otherwise fall back to the mapping's writepage(). 387 * 388 * FIXME: This code wants an estimate of how many pages are still to be 389 * written, so it can intelligently allocate a suitably-sized BIO. For now, 390 * just allocate full-size (16-page) BIOs. 391 */ 392 static struct bio * 393 __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block, 394 sector_t *last_block_in_bio, int *ret, struct writeback_control *wbc, 395 writepage_t writepage_fn) 396 { 397 struct address_space *mapping = page->mapping; 398 struct inode *inode = page->mapping->host; 399 const unsigned blkbits = inode->i_blkbits; 400 unsigned long end_index; 401 const unsigned blocks_per_page = PAGE_CACHE_SIZE >> blkbits; 402 sector_t last_block; 403 sector_t block_in_file; 404 sector_t blocks[MAX_BUF_PER_PAGE]; 405 unsigned page_block; 406 unsigned first_unmapped = blocks_per_page; 407 struct block_device *bdev = NULL; 408 int boundary = 0; 409 sector_t boundary_block = 0; 410 struct block_device *boundary_bdev = NULL; 411 int length; 412 struct buffer_head map_bh; 413 loff_t i_size = i_size_read(inode); 414 415 if (page_has_buffers(page)) { 416 struct buffer_head *head = page_buffers(page); 417 struct buffer_head *bh = head; 418 419 /* If they're all mapped and dirty, do it */ 420 page_block = 0; 421 do { 422 BUG_ON(buffer_locked(bh)); 423 if (!buffer_mapped(bh)) { 424 /* 425 * unmapped dirty buffers are created by 426 * __set_page_dirty_buffers -> mmapped data 427 */ 428 if (buffer_dirty(bh)) 429 goto confused; 430 if (first_unmapped == blocks_per_page) 431 first_unmapped = page_block; 432 continue; 433 } 434 435 if (first_unmapped != blocks_per_page) 436 goto confused; /* hole -> non-hole */ 437 438 if (!buffer_dirty(bh) || !buffer_uptodate(bh)) 439 goto confused; 440 if (page_block) { 441 if (bh->b_blocknr != blocks[page_block-1] + 1) 442 goto confused; 443 } 444 blocks[page_block++] = bh->b_blocknr; 445 boundary = buffer_boundary(bh); 446 if (boundary) { 447 boundary_block = bh->b_blocknr; 448 boundary_bdev = bh->b_bdev; 449 } 450 bdev = bh->b_bdev; 451 } while ((bh = bh->b_this_page) != head); 452 453 if (first_unmapped) 454 goto page_is_mapped; 455 456 /* 457 * Page has buffers, but they are all unmapped. The page was 458 * created by pagein or read over a hole which was handled by 459 * block_read_full_page(). If this address_space is also 460 * using mpage_readpages then this can rarely happen. 461 */ 462 goto confused; 463 } 464 465 /* 466 * The page has no buffers: map it to disk 467 */ 468 BUG_ON(!PageUptodate(page)); 469 block_in_file = page->index << (PAGE_CACHE_SHIFT - blkbits); 470 last_block = (i_size - 1) >> blkbits; 471 map_bh.b_page = page; 472 for (page_block = 0; page_block < blocks_per_page; ) { 473 474 map_bh.b_state = 0; 475 if (get_block(inode, block_in_file, &map_bh, 1)) 476 goto confused; 477 if (buffer_new(&map_bh)) 478 unmap_underlying_metadata(map_bh.b_bdev, 479 map_bh.b_blocknr); 480 if (buffer_boundary(&map_bh)) { 481 boundary_block = map_bh.b_blocknr; 482 boundary_bdev = map_bh.b_bdev; 483 } 484 if (page_block) { 485 if (map_bh.b_blocknr != blocks[page_block-1] + 1) 486 goto confused; 487 } 488 blocks[page_block++] = map_bh.b_blocknr; 489 boundary = buffer_boundary(&map_bh); 490 bdev = map_bh.b_bdev; 491 if (block_in_file == last_block) 492 break; 493 block_in_file++; 494 } 495 BUG_ON(page_block == 0); 496 497 first_unmapped = page_block; 498 499 page_is_mapped: 500 end_index = i_size >> PAGE_CACHE_SHIFT; 501 if (page->index >= end_index) { 502 /* 503 * The page straddles i_size. It must be zeroed out on each 504 * and every writepage invokation because it may be mmapped. 505 * "A file is mapped in multiples of the page size. For a file 506 * that is not a multiple of the page size, the remaining memory 507 * is zeroed when mapped, and writes to that region are not 508 * written out to the file." 509 */ 510 unsigned offset = i_size & (PAGE_CACHE_SIZE - 1); 511 char *kaddr; 512 513 if (page->index > end_index || !offset) 514 goto confused; 515 kaddr = kmap_atomic(page, KM_USER0); 516 memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset); 517 flush_dcache_page(page); 518 kunmap_atomic(kaddr, KM_USER0); 519 } 520 521 /* 522 * This page will go to BIO. Do we need to send this BIO off first? 523 */ 524 if (bio && *last_block_in_bio != blocks[0] - 1) 525 bio = mpage_bio_submit(WRITE, bio); 526 527 alloc_new: 528 if (bio == NULL) { 529 bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9), 530 bio_get_nr_vecs(bdev), GFP_NOFS|__GFP_HIGH); 531 if (bio == NULL) 532 goto confused; 533 } 534 535 /* 536 * Must try to add the page before marking the buffer clean or 537 * the confused fail path above (OOM) will be very confused when 538 * it finds all bh marked clean (i.e. it will not write anything) 539 */ 540 length = first_unmapped << blkbits; 541 if (bio_add_page(bio, page, length, 0) < length) { 542 bio = mpage_bio_submit(WRITE, bio); 543 goto alloc_new; 544 } 545 546 /* 547 * OK, we have our BIO, so we can now mark the buffers clean. Make 548 * sure to only clean buffers which we know we'll be writing. 549 */ 550 if (page_has_buffers(page)) { 551 struct buffer_head *head = page_buffers(page); 552 struct buffer_head *bh = head; 553 unsigned buffer_counter = 0; 554 555 do { 556 if (buffer_counter++ == first_unmapped) 557 break; 558 clear_buffer_dirty(bh); 559 bh = bh->b_this_page; 560 } while (bh != head); 561 562 /* 563 * we cannot drop the bh if the page is not uptodate 564 * or a concurrent readpage would fail to serialize with the bh 565 * and it would read from disk before we reach the platter. 566 */ 567 if (buffer_heads_over_limit && PageUptodate(page)) 568 try_to_free_buffers(page); 569 } 570 571 BUG_ON(PageWriteback(page)); 572 set_page_writeback(page); 573 unlock_page(page); 574 if (boundary || (first_unmapped != blocks_per_page)) { 575 bio = mpage_bio_submit(WRITE, bio); 576 if (boundary_block) { 577 write_boundary_block(boundary_bdev, 578 boundary_block, 1 << blkbits); 579 } 580 } else { 581 *last_block_in_bio = blocks[blocks_per_page - 1]; 582 } 583 goto out; 584 585 confused: 586 if (bio) 587 bio = mpage_bio_submit(WRITE, bio); 588 589 if (writepage_fn) { 590 *ret = (*writepage_fn)(page, wbc); 591 } else { 592 *ret = -EAGAIN; 593 goto out; 594 } 595 /* 596 * The caller has a ref on the inode, so *mapping is stable 597 */ 598 if (*ret) { 599 if (*ret == -ENOSPC) 600 set_bit(AS_ENOSPC, &mapping->flags); 601 else 602 set_bit(AS_EIO, &mapping->flags); 603 } 604 out: 605 return bio; 606 } 607 608 /** 609 * mpage_writepages - walk the list of dirty pages of the given 610 * address space and writepage() all of them. 611 * 612 * @mapping: address space structure to write 613 * @wbc: subtract the number of written pages from *@wbc->nr_to_write 614 * @get_block: the filesystem's block mapper function. 615 * If this is NULL then use a_ops->writepage. Otherwise, go 616 * direct-to-BIO. 617 * 618 * This is a library function, which implements the writepages() 619 * address_space_operation. 620 * 621 * If a page is already under I/O, generic_writepages() skips it, even 622 * if it's dirty. This is desirable behaviour for memory-cleaning writeback, 623 * but it is INCORRECT for data-integrity system calls such as fsync(). fsync() 624 * and msync() need to guarantee that all the data which was dirty at the time 625 * the call was made get new I/O started against them. If wbc->sync_mode is 626 * WB_SYNC_ALL then we were called for data integrity and we must wait for 627 * existing IO to complete. 628 */ 629 int 630 mpage_writepages(struct address_space *mapping, 631 struct writeback_control *wbc, get_block_t get_block) 632 { 633 struct backing_dev_info *bdi = mapping->backing_dev_info; 634 struct bio *bio = NULL; 635 sector_t last_block_in_bio = 0; 636 int ret = 0; 637 int done = 0; 638 int (*writepage)(struct page *page, struct writeback_control *wbc); 639 struct pagevec pvec; 640 int nr_pages; 641 pgoff_t index; 642 pgoff_t end = -1; /* Inclusive */ 643 int scanned = 0; 644 int is_range = 0; 645 646 if (wbc->nonblocking && bdi_write_congested(bdi)) { 647 wbc->encountered_congestion = 1; 648 return 0; 649 } 650 651 writepage = NULL; 652 if (get_block == NULL) 653 writepage = mapping->a_ops->writepage; 654 655 pagevec_init(&pvec, 0); 656 if (wbc->sync_mode == WB_SYNC_NONE) { 657 index = mapping->writeback_index; /* Start from prev offset */ 658 } else { 659 index = 0; /* whole-file sweep */ 660 scanned = 1; 661 } 662 if (wbc->start || wbc->end) { 663 index = wbc->start >> PAGE_CACHE_SHIFT; 664 end = wbc->end >> PAGE_CACHE_SHIFT; 665 is_range = 1; 666 scanned = 1; 667 } 668 retry: 669 while (!done && (index <= end) && 670 (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, 671 PAGECACHE_TAG_DIRTY, 672 min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) { 673 unsigned i; 674 675 scanned = 1; 676 for (i = 0; i < nr_pages; i++) { 677 struct page *page = pvec.pages[i]; 678 679 /* 680 * At this point we hold neither mapping->tree_lock nor 681 * lock on the page itself: the page may be truncated or 682 * invalidated (changing page->mapping to NULL), or even 683 * swizzled back from swapper_space to tmpfs file 684 * mapping 685 */ 686 687 lock_page(page); 688 689 if (unlikely(page->mapping != mapping)) { 690 unlock_page(page); 691 continue; 692 } 693 694 if (unlikely(is_range) && page->index > end) { 695 done = 1; 696 unlock_page(page); 697 continue; 698 } 699 700 if (wbc->sync_mode != WB_SYNC_NONE) 701 wait_on_page_writeback(page); 702 703 if (PageWriteback(page) || 704 !clear_page_dirty_for_io(page)) { 705 unlock_page(page); 706 continue; 707 } 708 709 if (writepage) { 710 ret = (*writepage)(page, wbc); 711 if (ret) { 712 if (ret == -ENOSPC) 713 set_bit(AS_ENOSPC, 714 &mapping->flags); 715 else 716 set_bit(AS_EIO, 717 &mapping->flags); 718 } 719 } else { 720 bio = __mpage_writepage(bio, page, get_block, 721 &last_block_in_bio, &ret, wbc, 722 page->mapping->a_ops->writepage); 723 } 724 if (unlikely(ret == WRITEPAGE_ACTIVATE)) 725 unlock_page(page); 726 if (ret || (--(wbc->nr_to_write) <= 0)) 727 done = 1; 728 if (wbc->nonblocking && bdi_write_congested(bdi)) { 729 wbc->encountered_congestion = 1; 730 done = 1; 731 } 732 } 733 pagevec_release(&pvec); 734 cond_resched(); 735 } 736 if (!scanned && !done) { 737 /* 738 * We hit the last page and there is more work to be done: wrap 739 * back to the start of the file 740 */ 741 scanned = 1; 742 index = 0; 743 goto retry; 744 } 745 if (!is_range) 746 mapping->writeback_index = index; 747 if (bio) 748 mpage_bio_submit(WRITE, bio); 749 return ret; 750 } 751 EXPORT_SYMBOL(mpage_writepages); 752 753 int mpage_writepage(struct page *page, get_block_t get_block, 754 struct writeback_control *wbc) 755 { 756 int ret = 0; 757 struct bio *bio; 758 sector_t last_block_in_bio = 0; 759 760 bio = __mpage_writepage(NULL, page, get_block, 761 &last_block_in_bio, &ret, wbc, NULL); 762 if (bio) 763 mpage_bio_submit(WRITE, bio); 764 765 return ret; 766 } 767 EXPORT_SYMBOL(mpage_writepage); 768