1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
4 * Copyright (c) 2016-2018 Christoph Hellwig.
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_log_format.h"
11 #include "xfs_trans_resv.h"
12 #include "xfs_mount.h"
13 #include "xfs_inode.h"
14 #include "xfs_trans.h"
15 #include "xfs_inode_item.h"
16 #include "xfs_alloc.h"
17 #include "xfs_error.h"
18 #include "xfs_iomap.h"
19 #include "xfs_trace.h"
21 #include "xfs_bmap_util.h"
22 #include "xfs_bmap_btree.h"
23 #include "xfs_reflink.h"
24 #include <linux/writeback.h>
27 * structure owned by writepages passed to individual writepage calls
29 struct xfs_writepage_ctx {
30 struct xfs_bmbt_irec imap;
33 struct xfs_ioend *ioend;
37 xfs_find_bdev_for_inode(
40 struct xfs_inode *ip = XFS_I(inode);
41 struct xfs_mount *mp = ip->i_mount;
43 if (XFS_IS_REALTIME_INODE(ip))
44 return mp->m_rtdev_targp->bt_bdev;
46 return mp->m_ddev_targp->bt_bdev;
50 xfs_find_daxdev_for_inode(
53 struct xfs_inode *ip = XFS_I(inode);
54 struct xfs_mount *mp = ip->i_mount;
56 if (XFS_IS_REALTIME_INODE(ip))
57 return mp->m_rtdev_targp->bt_daxdev;
59 return mp->m_ddev_targp->bt_daxdev;
63 xfs_finish_page_writeback(
68 struct iomap_page *iop = to_iomap_page(bvec->bv_page);
71 SetPageError(bvec->bv_page);
72 mapping_set_error(inode->i_mapping, -EIO);
75 ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
76 ASSERT(!iop || atomic_read(&iop->write_count) > 0);
78 if (!iop || atomic_dec_and_test(&iop->write_count))
79 end_page_writeback(bvec->bv_page);
83 * We're now finished for good with this ioend structure. Update the page
84 * state, release holds on bios, and finally free up memory. Do not use the
89 struct xfs_ioend *ioend,
92 struct inode *inode = ioend->io_inode;
93 struct bio *bio = &ioend->io_inline_bio;
94 struct bio *last = ioend->io_bio, *next;
95 u64 start = bio->bi_iter.bi_sector;
96 bool quiet = bio_flagged(bio, BIO_QUIET);
98 for (bio = &ioend->io_inline_bio; bio; bio = next) {
101 struct bvec_iter_all iter_all;
104 * For the last bio, bi_private points to the ioend, so we
105 * need to explicitly end the iteration here.
110 next = bio->bi_private;
112 /* walk each page on bio, ending page IO on them */
113 bio_for_each_segment_all(bvec, bio, i, iter_all)
114 xfs_finish_page_writeback(inode, bvec, error);
118 if (unlikely(error && !quiet)) {
119 xfs_err_ratelimited(XFS_I(inode)->i_mount,
120 "writeback error on sector %llu", start);
125 * Fast and loose check if this write could update the on-disk inode size.
127 static inline bool xfs_ioend_is_append(struct xfs_ioend *ioend)
129 return ioend->io_offset + ioend->io_size >
130 XFS_I(ioend->io_inode)->i_d.di_size;
134 xfs_setfilesize_trans_alloc(
135 struct xfs_ioend *ioend)
137 struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
138 struct xfs_trans *tp;
141 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0,
142 XFS_TRANS_NOFS, &tp);
146 ioend->io_append_trans = tp;
149 * We may pass freeze protection with a transaction. So tell lockdep
152 __sb_writers_release(ioend->io_inode->i_sb, SB_FREEZE_FS);
154 * We hand off the transaction to the completion thread now, so
155 * clear the flag here.
157 current_restore_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
162 * Update on-disk file size now that data has been written to disk.
166 struct xfs_inode *ip,
167 struct xfs_trans *tp,
173 xfs_ilock(ip, XFS_ILOCK_EXCL);
174 isize = xfs_new_eof(ip, offset + size);
176 xfs_iunlock(ip, XFS_ILOCK_EXCL);
177 xfs_trans_cancel(tp);
181 trace_xfs_setfilesize(ip, offset, size);
183 ip->i_d.di_size = isize;
184 xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
185 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
187 return xfs_trans_commit(tp);
192 struct xfs_inode *ip,
196 struct xfs_mount *mp = ip->i_mount;
197 struct xfs_trans *tp;
200 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp);
204 return __xfs_setfilesize(ip, tp, offset, size);
208 xfs_setfilesize_ioend(
209 struct xfs_ioend *ioend,
212 struct xfs_inode *ip = XFS_I(ioend->io_inode);
213 struct xfs_trans *tp = ioend->io_append_trans;
216 * The transaction may have been allocated in the I/O submission thread,
217 * thus we need to mark ourselves as being in a transaction manually.
218 * Similarly for freeze protection.
220 current_set_flags_nested(&tp->t_pflags, PF_MEMALLOC_NOFS);
221 __sb_writers_acquired(VFS_I(ip)->i_sb, SB_FREEZE_FS);
223 /* we abort the update if there was an IO error */
225 xfs_trans_cancel(tp);
229 return __xfs_setfilesize(ip, tp, ioend->io_offset, ioend->io_size);
233 * IO write completion.
237 struct work_struct *work)
239 struct xfs_ioend *ioend =
240 container_of(work, struct xfs_ioend, io_work);
241 struct xfs_inode *ip = XFS_I(ioend->io_inode);
242 xfs_off_t offset = ioend->io_offset;
243 size_t size = ioend->io_size;
247 * Just clean up the in-memory strutures if the fs has been shut down.
249 if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
255 * Clean up any COW blocks on an I/O error.
257 error = blk_status_to_errno(ioend->io_bio->bi_status);
258 if (unlikely(error)) {
259 switch (ioend->io_type) {
261 xfs_reflink_cancel_cow_range(ip, offset, size, true);
269 * Success: commit the COW or unwritten blocks if needed.
271 switch (ioend->io_type) {
273 error = xfs_reflink_end_cow(ip, offset, size);
275 case XFS_IO_UNWRITTEN:
276 /* writeback should never update isize */
277 error = xfs_iomap_write_unwritten(ip, offset, size, false);
280 ASSERT(!xfs_ioend_is_append(ioend) || ioend->io_append_trans);
285 if (ioend->io_append_trans)
286 error = xfs_setfilesize_ioend(ioend, error);
287 xfs_destroy_ioend(ioend, error);
294 struct xfs_ioend *ioend = bio->bi_private;
295 struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount;
297 if (ioend->io_type == XFS_IO_UNWRITTEN || ioend->io_type == XFS_IO_COW)
298 queue_work(mp->m_unwritten_workqueue, &ioend->io_work);
299 else if (ioend->io_append_trans)
300 queue_work(mp->m_data_workqueue, &ioend->io_work);
302 xfs_destroy_ioend(ioend, blk_status_to_errno(bio->bi_status));
307 struct xfs_writepage_ctx *wpc,
311 struct xfs_inode *ip = XFS_I(inode);
312 struct xfs_mount *mp = ip->i_mount;
313 ssize_t count = i_blocksize(inode);
314 xfs_fileoff_t offset_fsb = XFS_B_TO_FSBT(mp, offset), end_fsb;
315 xfs_fileoff_t cow_fsb = NULLFILEOFF;
316 struct xfs_bmbt_irec imap;
317 int whichfork = XFS_DATA_FORK;
318 struct xfs_iext_cursor icur;
323 * We have to make sure the cached mapping is within EOF to protect
324 * against eofblocks trimming on file release leaving us with a stale
325 * mapping. Otherwise, a page for a subsequent file extending buffered
326 * write could get picked up by this writeback cycle and written to the
329 * Note that what we really want here is a generic mapping invalidation
330 * mechanism to protect us from arbitrary extent modifying contexts, not
333 xfs_trim_extent_eof(&wpc->imap, ip);
336 * COW fork blocks can overlap data fork blocks even if the blocks
337 * aren't shared. COW I/O always takes precedent, so we must always
338 * check for overlap on reflink inodes unless the mapping is already a
339 * COW one, or the COW fork hasn't changed from the last time we looked
342 * It's safe to check the COW fork if_seq here without the ILOCK because
343 * we've indirectly protected against concurrent updates: writeback has
344 * the page locked, which prevents concurrent invalidations by reflink
345 * and directio and prevents concurrent buffered writes to the same
346 * page. Changes to if_seq always happen under i_lock, which protects
347 * against concurrent updates and provides a memory barrier on the way
348 * out that ensures that we always see the current value.
350 imap_valid = offset_fsb >= wpc->imap.br_startoff &&
351 offset_fsb < wpc->imap.br_startoff + wpc->imap.br_blockcount;
353 (!xfs_inode_has_cow_data(ip) ||
354 wpc->io_type == XFS_IO_COW ||
355 wpc->cow_seq == READ_ONCE(ip->i_cowfp->if_seq)))
358 if (XFS_FORCED_SHUTDOWN(mp))
362 * If we don't have a valid map, now it's time to get a new one for this
363 * offset. This will convert delayed allocations (including COW ones)
364 * into real extents. If we return without a valid map, it means we
365 * landed in a hole and we skip the block.
367 xfs_ilock(ip, XFS_ILOCK_SHARED);
368 ASSERT(ip->i_d.di_format != XFS_DINODE_FMT_BTREE ||
369 (ip->i_df.if_flags & XFS_IFEXTENTS));
370 ASSERT(offset <= mp->m_super->s_maxbytes);
372 if (offset > mp->m_super->s_maxbytes - count)
373 count = mp->m_super->s_maxbytes - offset;
374 end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
377 * Check if this is offset is covered by a COW extents, and if yes use
378 * it directly instead of looking up anything in the data fork.
380 if (xfs_inode_has_cow_data(ip) &&
381 xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap))
382 cow_fsb = imap.br_startoff;
383 if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) {
384 wpc->cow_seq = READ_ONCE(ip->i_cowfp->if_seq);
385 xfs_iunlock(ip, XFS_ILOCK_SHARED);
387 * Truncate can race with writeback since writeback doesn't
388 * take the iolock and truncate decreases the file size before
389 * it starts truncating the pages between new_size and old_size.
390 * Therefore, we can end up in the situation where writeback
391 * gets a CoW fork mapping but the truncate makes the mapping
392 * invalid and we end up in here trying to get a new mapping.
393 * bail out here so that we simply never get a valid mapping
394 * and so we drop the write altogether. The page truncation
395 * will kill the contents anyway.
397 if (offset > i_size_read(inode)) {
398 wpc->io_type = XFS_IO_HOLE;
401 whichfork = XFS_COW_FORK;
402 wpc->io_type = XFS_IO_COW;
403 goto allocate_blocks;
407 * Map valid and no COW extent in the way? We're done.
410 xfs_iunlock(ip, XFS_ILOCK_SHARED);
415 * If we don't have a valid map, now it's time to get a new one for this
416 * offset. This will convert delayed allocations (including COW ones)
419 if (!xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap))
420 imap.br_startoff = end_fsb; /* fake a hole past EOF */
421 xfs_iunlock(ip, XFS_ILOCK_SHARED);
423 if (imap.br_startoff > offset_fsb) {
424 /* landed in a hole or beyond EOF */
425 imap.br_blockcount = imap.br_startoff - offset_fsb;
426 imap.br_startoff = offset_fsb;
427 imap.br_startblock = HOLESTARTBLOCK;
428 wpc->io_type = XFS_IO_HOLE;
431 * Truncate to the next COW extent if there is one. This is the
432 * only opportunity to do this because we can skip COW fork
433 * lookups for the subsequent blocks in the mapping; however,
434 * the requirement to treat the COW range separately remains.
436 if (cow_fsb != NULLFILEOFF &&
437 cow_fsb < imap.br_startoff + imap.br_blockcount)
438 imap.br_blockcount = cow_fsb - imap.br_startoff;
440 if (isnullstartblock(imap.br_startblock)) {
441 /* got a delalloc extent */
442 wpc->io_type = XFS_IO_DELALLOC;
443 goto allocate_blocks;
446 if (imap.br_state == XFS_EXT_UNWRITTEN)
447 wpc->io_type = XFS_IO_UNWRITTEN;
449 wpc->io_type = XFS_IO_OVERWRITE;
453 trace_xfs_map_blocks_found(ip, offset, count, wpc->io_type, &imap);
456 error = xfs_iomap_write_allocate(ip, whichfork, offset, &imap,
460 ASSERT(whichfork == XFS_COW_FORK || cow_fsb == NULLFILEOFF ||
461 imap.br_startoff + imap.br_blockcount <= cow_fsb);
463 trace_xfs_map_blocks_alloc(ip, offset, count, wpc->io_type, &imap);
468 * Submit the bio for an ioend. We are passed an ioend with a bio attached to
469 * it, and we submit that bio. The ioend may be used for multiple bio
470 * submissions, so we only want to allocate an append transaction for the ioend
471 * once. In the case of multiple bio submission, each bio will take an IO
472 * reference to the ioend to ensure that the ioend completion is only done once
473 * all bios have been submitted and the ioend is really done.
475 * If @fail is non-zero, it means that we have a situation where some part of
476 * the submission process has failed after we have marked paged for writeback
477 * and unlocked them. In this situation, we need to fail the bio and ioend
478 * rather than submit it to IO. This typically only happens on a filesystem
483 struct writeback_control *wbc,
484 struct xfs_ioend *ioend,
487 /* Convert CoW extents to regular */
488 if (!status && ioend->io_type == XFS_IO_COW) {
490 * Yuk. This can do memory allocation, but is not a
491 * transactional operation so everything is done in GFP_KERNEL
492 * context. That can deadlock, because we hold pages in
493 * writeback state and GFP_KERNEL allocations can block on them.
494 * Hence we must operate in nofs conditions here.
498 nofs_flag = memalloc_nofs_save();
499 status = xfs_reflink_convert_cow(XFS_I(ioend->io_inode),
500 ioend->io_offset, ioend->io_size);
501 memalloc_nofs_restore(nofs_flag);
504 /* Reserve log space if we might write beyond the on-disk inode size. */
506 ioend->io_type != XFS_IO_UNWRITTEN &&
507 xfs_ioend_is_append(ioend) &&
508 !ioend->io_append_trans)
509 status = xfs_setfilesize_trans_alloc(ioend);
511 ioend->io_bio->bi_private = ioend;
512 ioend->io_bio->bi_end_io = xfs_end_bio;
513 ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
516 * If we are failing the IO now, just mark the ioend with an
517 * error and finish it. This will run IO completion immediately
518 * as there is only one reference to the ioend at this point in
522 ioend->io_bio->bi_status = errno_to_blk_status(status);
523 bio_endio(ioend->io_bio);
527 ioend->io_bio->bi_write_hint = ioend->io_inode->i_write_hint;
528 submit_bio(ioend->io_bio);
532 static struct xfs_ioend *
537 struct block_device *bdev,
540 struct xfs_ioend *ioend;
543 bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, &xfs_ioend_bioset);
544 bio_set_dev(bio, bdev);
545 bio->bi_iter.bi_sector = sector;
547 ioend = container_of(bio, struct xfs_ioend, io_inline_bio);
548 INIT_LIST_HEAD(&ioend->io_list);
549 ioend->io_type = type;
550 ioend->io_inode = inode;
552 ioend->io_offset = offset;
553 INIT_WORK(&ioend->io_work, xfs_end_io);
554 ioend->io_append_trans = NULL;
560 * Allocate a new bio, and chain the old bio to the new one.
562 * Note that we have to do perform the chaining in this unintuitive order
563 * so that the bi_private linkage is set up in the right direction for the
564 * traversal in xfs_destroy_ioend().
568 struct xfs_ioend *ioend,
569 struct writeback_control *wbc,
570 struct block_device *bdev,
575 new = bio_alloc(GFP_NOFS, BIO_MAX_PAGES);
576 bio_set_dev(new, bdev);
577 new->bi_iter.bi_sector = sector;
578 bio_chain(ioend->io_bio, new);
579 bio_get(ioend->io_bio); /* for xfs_destroy_ioend */
580 ioend->io_bio->bi_opf = REQ_OP_WRITE | wbc_to_write_flags(wbc);
581 ioend->io_bio->bi_write_hint = ioend->io_inode->i_write_hint;
582 submit_bio(ioend->io_bio);
587 * Test to see if we have an existing ioend structure that we could append to
588 * first, otherwise finish off the current ioend and start another.
595 struct iomap_page *iop,
596 struct xfs_writepage_ctx *wpc,
597 struct writeback_control *wbc,
598 struct list_head *iolist)
600 struct xfs_inode *ip = XFS_I(inode);
601 struct xfs_mount *mp = ip->i_mount;
602 struct block_device *bdev = xfs_find_bdev_for_inode(inode);
603 unsigned len = i_blocksize(inode);
604 unsigned poff = offset & (PAGE_SIZE - 1);
607 sector = xfs_fsb_to_db(ip, wpc->imap.br_startblock) +
608 ((offset - XFS_FSB_TO_B(mp, wpc->imap.br_startoff)) >> 9);
610 if (!wpc->ioend || wpc->io_type != wpc->ioend->io_type ||
611 sector != bio_end_sector(wpc->ioend->io_bio) ||
612 offset != wpc->ioend->io_offset + wpc->ioend->io_size) {
614 list_add(&wpc->ioend->io_list, iolist);
615 wpc->ioend = xfs_alloc_ioend(inode, wpc->io_type, offset,
619 if (!__bio_try_merge_page(wpc->ioend->io_bio, page, len, poff)) {
621 atomic_inc(&iop->write_count);
622 if (bio_full(wpc->ioend->io_bio))
623 xfs_chain_bio(wpc->ioend, wbc, bdev, sector);
624 __bio_add_page(wpc->ioend->io_bio, page, len, poff);
627 wpc->ioend->io_size += len;
631 xfs_vm_invalidatepage(
636 trace_xfs_invalidatepage(page->mapping->host, page, offset, length);
637 iomap_invalidatepage(page, offset, length);
641 * If the page has delalloc blocks on it, we need to punch them out before we
642 * invalidate the page. If we don't, we leave a stale delalloc mapping on the
643 * inode that can trip up a later direct I/O read operation on the same region.
645 * We prevent this by truncating away the delalloc regions on the page. Because
646 * they are delalloc, we can do this without needing a transaction. Indeed - if
647 * we get ENOSPC errors, we have to be able to do this truncation without a
648 * transaction as there is no space left for block reservation (typically why we
649 * see a ENOSPC in writeback).
652 xfs_aops_discard_page(
655 struct inode *inode = page->mapping->host;
656 struct xfs_inode *ip = XFS_I(inode);
657 struct xfs_mount *mp = ip->i_mount;
658 loff_t offset = page_offset(page);
659 xfs_fileoff_t start_fsb = XFS_B_TO_FSBT(mp, offset);
662 if (XFS_FORCED_SHUTDOWN(mp))
666 "page discard on page "PTR_FMT", inode 0x%llx, offset %llu.",
667 page, ip->i_ino, offset);
669 error = xfs_bmap_punch_delalloc_range(ip, start_fsb,
670 PAGE_SIZE / i_blocksize(inode));
671 if (error && !XFS_FORCED_SHUTDOWN(mp))
672 xfs_alert(mp, "page discard unable to remove delalloc mapping.");
674 xfs_vm_invalidatepage(page, 0, PAGE_SIZE);
678 * We implement an immediate ioend submission policy here to avoid needing to
679 * chain multiple ioends and hence nest mempool allocations which can violate
680 * forward progress guarantees we need to provide. The current ioend we are
681 * adding blocks to is cached on the writepage context, and if the new block
682 * does not append to the cached ioend it will create a new ioend and cache that
685 * If a new ioend is created and cached, the old ioend is returned and queued
686 * locally for submission once the entire page is processed or an error has been
687 * detected. While ioends are submitted immediately after they are completed,
688 * batching optimisations are provided by higher level block plugging.
690 * At the end of a writeback pass, there will be a cached ioend remaining on the
691 * writepage context that the caller will need to submit.
695 struct xfs_writepage_ctx *wpc,
696 struct writeback_control *wbc,
701 LIST_HEAD(submit_list);
702 struct iomap_page *iop = to_iomap_page(page);
703 unsigned len = i_blocksize(inode);
704 struct xfs_ioend *ioend, *next;
705 uint64_t file_offset; /* file offset of page */
706 int error = 0, count = 0, i;
708 ASSERT(iop || i_blocksize(inode) == PAGE_SIZE);
709 ASSERT(!iop || atomic_read(&iop->write_count) == 0);
712 * Walk through the page to find areas to write back. If we run off the
713 * end of the current map or find the current map invalid, grab a new
716 for (i = 0, file_offset = page_offset(page);
717 i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
718 i++, file_offset += len) {
719 if (iop && !test_bit(i, iop->uptodate))
722 error = xfs_map_blocks(wpc, inode, file_offset);
725 if (wpc->io_type == XFS_IO_HOLE)
727 xfs_add_to_ioend(inode, file_offset, page, iop, wpc, wbc,
732 ASSERT(wpc->ioend || list_empty(&submit_list));
733 ASSERT(PageLocked(page));
734 ASSERT(!PageWriteback(page));
737 * On error, we have to fail the ioend here because we may have set
738 * pages under writeback, we have to make sure we run IO completion to
739 * mark the error state of the IO appropriately, so we can't cancel the
740 * ioend directly here. That means we have to mark this page as under
741 * writeback if we included any blocks from it in the ioend chain so
742 * that completion treats it correctly.
744 * If we didn't include the page in the ioend, the on error we can
745 * simply discard and unlock it as there are no other users of the page
746 * now. The caller will still need to trigger submission of outstanding
747 * ioends on the writepage context so they are treated correctly on
750 if (unlikely(error)) {
752 xfs_aops_discard_page(page);
753 ClearPageUptodate(page);
759 * If the page was not fully cleaned, we need to ensure that the
760 * higher layers come back to it correctly. That means we need
761 * to keep the page dirty, and for WB_SYNC_ALL writeback we need
762 * to ensure the PAGECACHE_TAG_TOWRITE index mark is not removed
763 * so another attempt to write this page in this writeback sweep
766 set_page_writeback_keepwrite(page);
768 clear_page_dirty_for_io(page);
769 set_page_writeback(page);
775 * Preserve the original error if there was one, otherwise catch
776 * submission errors here and propagate into subsequent ioend
779 list_for_each_entry_safe(ioend, next, &submit_list, io_list) {
782 list_del_init(&ioend->io_list);
783 error2 = xfs_submit_ioend(wbc, ioend, error);
784 if (error2 && !error)
789 * We can end up here with no error and nothing to write only if we race
790 * with a partial page truncate on a sub-page block sized filesystem.
793 end_page_writeback(page);
795 mapping_set_error(page->mapping, error);
800 * Write out a dirty page.
802 * For delalloc space on the page we need to allocate space and flush it.
803 * For unwritten space on the page we need to start the conversion to
804 * regular allocated space.
809 struct writeback_control *wbc,
812 struct xfs_writepage_ctx *wpc = data;
813 struct inode *inode = page->mapping->host;
818 trace_xfs_writepage(inode, page, 0, 0);
821 * Refuse to write the page out if we are called from reclaim context.
823 * This avoids stack overflows when called from deeply used stacks in
824 * random callers for direct reclaim or memcg reclaim. We explicitly
825 * allow reclaim from kswapd as the stack usage there is relatively low.
827 * This should never happen except in the case of a VM regression so
830 if (WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD)) ==
835 * Given that we do not allow direct reclaim to call us, we should
836 * never be called while in a filesystem transaction.
838 if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS))
842 * Is this page beyond the end of the file?
844 * The page index is less than the end_index, adjust the end_offset
845 * to the highest offset that this page should represent.
846 * -----------------------------------------------------
847 * | file mapping | <EOF> |
848 * -----------------------------------------------------
849 * | Page ... | Page N-2 | Page N-1 | Page N | |
850 * ^--------------------------------^----------|--------
851 * | desired writeback range | see else |
852 * ---------------------------------^------------------|
854 offset = i_size_read(inode);
855 end_index = offset >> PAGE_SHIFT;
856 if (page->index < end_index)
857 end_offset = (xfs_off_t)(page->index + 1) << PAGE_SHIFT;
860 * Check whether the page to write out is beyond or straddles
862 * -------------------------------------------------------
863 * | file mapping | <EOF> |
864 * -------------------------------------------------------
865 * | Page ... | Page N-2 | Page N-1 | Page N | Beyond |
866 * ^--------------------------------^-----------|---------
868 * ---------------------------------^-----------|--------|
870 unsigned offset_into_page = offset & (PAGE_SIZE - 1);
873 * Skip the page if it is fully outside i_size, e.g. due to a
874 * truncate operation that is in progress. We must redirty the
875 * page so that reclaim stops reclaiming it. Otherwise
876 * xfs_vm_releasepage() is called on it and gets confused.
878 * Note that the end_index is unsigned long, it would overflow
879 * if the given offset is greater than 16TB on 32-bit system
880 * and if we do check the page is fully outside i_size or not
881 * via "if (page->index >= end_index + 1)" as "end_index + 1"
882 * will be evaluated to 0. Hence this page will be redirtied
883 * and be written out repeatedly which would result in an
884 * infinite loop, the user program that perform this operation
885 * will hang. Instead, we can verify this situation by checking
886 * if the page to write is totally beyond the i_size or if it's
887 * offset is just equal to the EOF.
889 if (page->index > end_index ||
890 (page->index == end_index && offset_into_page == 0))
894 * The page straddles i_size. It must be zeroed out on each
895 * and every writepage invocation because it may be mmapped.
896 * "A file is mapped in multiples of the page size. For a file
897 * that is not a multiple of the page size, the remaining
898 * memory is zeroed when mapped, and writes to that region are
899 * not written out to the file."
901 zero_user_segment(page, offset_into_page, PAGE_SIZE);
903 /* Adjust the end_offset to the end of file */
907 return xfs_writepage_map(wpc, wbc, inode, page, end_offset);
910 redirty_page_for_writepage(wbc, page);
918 struct writeback_control *wbc)
920 struct xfs_writepage_ctx wpc = {
921 .io_type = XFS_IO_HOLE,
925 ret = xfs_do_writepage(page, wbc, &wpc);
927 ret = xfs_submit_ioend(wbc, wpc.ioend, ret);
933 struct address_space *mapping,
934 struct writeback_control *wbc)
936 struct xfs_writepage_ctx wpc = {
937 .io_type = XFS_IO_HOLE,
941 xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
942 ret = write_cache_pages(mapping, wbc, xfs_do_writepage, &wpc);
944 ret = xfs_submit_ioend(wbc, wpc.ioend, ret);
950 struct address_space *mapping,
951 struct writeback_control *wbc)
953 xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED);
954 return dax_writeback_mapping_range(mapping,
955 xfs_find_bdev_for_inode(mapping->host), wbc);
963 trace_xfs_releasepage(page->mapping->host, page, 0, 0);
964 return iomap_releasepage(page, gfp_mask);
969 struct address_space *mapping,
972 struct xfs_inode *ip = XFS_I(mapping->host);
974 trace_xfs_vm_bmap(ip);
977 * The swap code (ab-)uses ->bmap to get a block mapping and then
978 * bypasses the file system for actual I/O. We really can't allow
979 * that on reflinks inodes, so we have to skip out here. And yes,
980 * 0 is the magic code for a bmap error.
982 * Since we don't pass back blockdev info, we can't return bmap
983 * information for rt files either.
985 if (xfs_is_reflink_inode(ip) || XFS_IS_REALTIME_INODE(ip))
987 return iomap_bmap(mapping, block, &xfs_iomap_ops);
995 trace_xfs_vm_readpage(page->mapping->host, 1);
996 return iomap_readpage(page, &xfs_iomap_ops);
1001 struct file *unused,
1002 struct address_space *mapping,
1003 struct list_head *pages,
1006 trace_xfs_vm_readpages(mapping->host, nr_pages);
1007 return iomap_readpages(mapping, pages, nr_pages, &xfs_iomap_ops);
1011 xfs_iomap_swapfile_activate(
1012 struct swap_info_struct *sis,
1013 struct file *swap_file,
1016 sis->bdev = xfs_find_bdev_for_inode(file_inode(swap_file));
1017 return iomap_swapfile_activate(sis, swap_file, span, &xfs_iomap_ops);
1020 const struct address_space_operations xfs_address_space_operations = {
1021 .readpage = xfs_vm_readpage,
1022 .readpages = xfs_vm_readpages,
1023 .writepage = xfs_vm_writepage,
1024 .writepages = xfs_vm_writepages,
1025 .set_page_dirty = iomap_set_page_dirty,
1026 .releasepage = xfs_vm_releasepage,
1027 .invalidatepage = xfs_vm_invalidatepage,
1028 .bmap = xfs_vm_bmap,
1029 .direct_IO = noop_direct_IO,
1030 .migratepage = iomap_migrate_page,
1031 .is_partially_uptodate = iomap_is_partially_uptodate,
1032 .error_remove_page = generic_error_remove_page,
1033 .swap_activate = xfs_iomap_swapfile_activate,
1036 const struct address_space_operations xfs_dax_aops = {
1037 .writepages = xfs_dax_writepages,
1038 .direct_IO = noop_direct_IO,
1039 .set_page_dirty = noop_set_page_dirty,
1040 .invalidatepage = noop_invalidatepage,
1041 .swap_activate = xfs_iomap_swapfile_activate,