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btrfs: move ordered extent cleanup to where they are allocated

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The ordered extent cleanup is hard to grasp because it doesn't follow
the common cleanup-asap pattern.

E.g. run_delalloc_nocow() and cow_file_range() allocate one or more
ordered extent, but if any error is hit, the cleanup is done later inside
btrfs_run_delalloc_range().

To change the existing delayed cleanup:

- Update the comment on error handling of run_delalloc_nocow()
  There are in fact 3 different cases other than 2 if we are doing
  ordered extents cleanup inside run_delalloc_nocow():

  1) @cow_start and @cow_end not set
     No fallback to COW at all.
     Before @cur_offset we need to cleanup the OE and page dirty.
     After @cur_offset just clear all involved page and extent flags.

  2) @cow_start set but @cow_end not set.
     This means we failed before even calling fallback_to_cow().
     It's just a variant of case 1), where it's @cow_start splitting
     the two parts (and we should just ignore @cur_offset since it's
     advanced without any new ordered extent).

  3) @cow_start and @cow_end both set
     This means fallback_to_cow() failed, meaning [start, cow_start)
     needs the regular OE and dirty folio cleanup, and skip range
     [cow_start, cow_end) as cow_file_range() has done the cleanup,
     and eventually cleanup [cow_end, end) range.

- Only reset @cow_start after fallback_to_cow() succeeded
  As above case 2) and 3) are both relying on @cow_start to determine
  the cleanup range.

- Move btrfs_cleanup_ordered_extents() into run_delalloc_nocow(),
  cow_file_range() and nocow_one_range()

  For cow_file_range() it's pretty straightforward and easy.

  For run_delalloc_nocow() refer to the above 3 different error cases.

  For nocow_one_range() if we hit an error, we need to cleanup the
  ordered extents by ourselves.
  And then it will fallback to case 1), since @cur_offset is not yet
  advanced, the existing cleanup will co-operate with nocow_one_range()
  well.

- Remove the btrfs_cleanup_ordered_extents() inside submit_uncompressed_range()
  As failed cow_file_range() will do all the proper cleanup now.

Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2025-01-13 14:09:24 +10:30 • committed by David Sterba
parent 10326fdcb3
commit 94f6c5c17e
1 changed files with 43 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

75
fs/btrfs/inode.c
View file

@ -1090,7 +1090,6 @@ static void submit_uncompressed_range(struct btrfs_inode *inode,
&wbc, false);
wbc_detach_inode(&wbc);
if (ret < 0) {
btrfs_cleanup_ordered_extents(inode, start, end - start + 1);
if (locked_folio)
btrfs_folio_end_lock(inode->root->fs_info, locked_folio,
start, async_extent->ram_size);
@ -1272,10 +1271,7 @@ u64 btrfs_get_extent_allocation_hint(struct btrfs_inode *inode, u64 start,
* - Else all pages except for @locked_folio are unlocked.
*
* When a failure happens in the second or later iteration of the
* while-loop, the ordered extents created in previous iterations are kept
* intact. So, the caller must clean them up by calling
* btrfs_cleanup_ordered_extents(). See btrfs_run_delalloc_range() for
* example.
* while-loop, the ordered extents created in previous iterations are cleaned up.
*/
static noinline int cow_file_range(struct btrfs_inode *inode,
struct folio *locked_folio, u64 start,
@ -1492,11 +1488,9 @@ out_unlock:
/*
* For the range (1). We have already instantiated the ordered extents
* for this region. They are cleaned up by
* btrfs_cleanup_ordered_extents() in e.g,
* btrfs_run_delalloc_range().
* for this region, thus we need to cleanup those ordered extents.
* EXTENT_DELALLOC_NEW | EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV
* are also handled by the cleanup function.
* are also handled by the ordered extents cleanup.
*
* So here we only clear EXTENT_LOCKED and EXTENT_DELALLOC flag, and
* finish the writeback of the involved folios, which will be never submitted.
@ -1507,6 +1501,8 @@ out_unlock:
if (!locked_folio)
mapping_set_error(inode->vfs_inode.i_mapping, ret);
btrfs_cleanup_ordered_extents(inode, orig_start, start - orig_start);
extent_clear_unlock_delalloc(inode, orig_start, start - 1,
locked_folio, NULL, clear_bits, page_ops);
}
@ -2024,12 +2020,14 @@ static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio
EXTENT_LOCKED | EXTENT_DELALLOC |
EXTENT_CLEAR_DATA_RESV,
PAGE_UNLOCK | PAGE_SET_ORDERED);
/*
* btrfs_reloc_clone_csums() error, now we're OK to call error handler,
* as metadata for created ordered extent will only be freed by
* btrfs_finish_ordered_io().
* On error, we need to cleanup the ordered extents we created.
*
* We do not clear the folio Dirty flags because they are set and
* cleaered by the caller.
*/
if (ret < 0)
btrfs_cleanup_ordered_extents(inode, file_pos, end);
return ret;
}
@ -2208,12 +2206,12 @@ must_cow:
if (cow_start != (u64)-1) {
ret = fallback_to_cow(inode, locked_folio, cow_start,
found_key.offset - 1);
cow_start = (u64)-1;
if (ret) {
cow_end = found_key.offset - 1;
btrfs_dec_nocow_writers(nocow_bg);
goto error;
}
cow_start = (u64)-1;
}
ret = nocow_one_range(inode, locked_folio, &cached_state,
@ -2231,11 +2229,11 @@ must_cow:
if (cow_start != (u64)-1) {
ret = fallback_to_cow(inode, locked_folio, cow_start, end);
cow_start = (u64)-1;
if (ret) {
cow_end = end;
goto error;
}
cow_start = (u64)-1;
}
btrfs_free_path(path);
@ -2249,27 +2247,44 @@ error:
* start cur_offset end
* |/////////////| |
*
* In this case, cow_start should be (u64)-1.
*
* For range [start, cur_offset) the folios are already unlocked (except
* @locked_folio), EXTENT_DELALLOC already removed.
* Only need to clear the dirty flag as they will never be submitted.
* Ordered extent and extent maps are handled by
* btrfs_mark_ordered_io_finished() inside run_delalloc_range().
* Need to clear the dirty flags and finish the ordered extents.
*
* 2) Failed with error from fallback_to_cow()
* start cur_offset cow_end end
* 2) Failed with error before calling fallback_to_cow()
*
* start cow_start end
* |/////////////| |
*
* In this case, only @cow_start is set, @cur_offset is between
* [cow_start, end)
*
* It's mostly the same as case 1), just replace @cur_offset with
* @cow_start.
*
* 3) Failed with error from fallback_to_cow()
*
* start cow_start cow_end end
* |/////////////|-----------| |
*
* For range [start, cur_offset) it's the same as case 1).
* But for range [cur_offset, cow_end), the folios have dirty flag
* cleared and unlocked, EXTENT_DEALLLOC cleared by cow_file_range().
* In this case, both @cow_start and @cow_end is set.
*
* Thus we should not call extent_clear_unlock_delalloc() on range
* [cur_offset, cow_end), as the folios are already unlocked.
* For range [start, cow_start) it's the same as case 1).
* But for range [cow_start, cow_end), all the cleanup is handled by
* cow_file_range(), we should not touch anything in that range.
*
* So clear the folio dirty flags for [start, cur_offset) first.
* So for all above cases, if @cow_start is set, cleanup ordered extents
* for range [start, @cow_start), other wise cleanup range [start, @cur_offset).
*/
if (cur_offset > start)
if (cow_start != (u64)-1)
cur_offset = cow_start;
if (cur_offset > start) {
btrfs_cleanup_ordered_extents(inode, start, cur_offset - start);
cleanup_dirty_folios(inode, locked_folio, start, cur_offset - 1, ret);
}
/*
* If an error happened while a COW region is outstanding, cur_offset
@ -2334,7 +2349,7 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct folio *locked_fol
if (should_nocow(inode, start, end)) {
ret = run_delalloc_nocow(inode, locked_folio, start, end);
goto out;
return ret;
}
if (btrfs_inode_can_compress(inode) &&
@ -2348,10 +2363,6 @@ int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct folio *locked_fol
else
ret = cow_file_range(inode, locked_folio, start, end, NULL,
false, false);
out:
if (ret < 0)
btrfs_cleanup_ordered_extents(inode, start, end - start + 1);
return ret;
}