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btrfs: make nocow_one_range() to do cleanup on error

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Currently if we hit an error inside nocow_one_range(), we do not clear
the page dirty, and let the caller to handle it.

This is very different compared to fallback_to_cow(), when that function
failed, everything will be cleaned up by cow_file_range().

Enhance the situation by:

- Use a common error handling for nocow_one_range()
  If we failed anything, use the same btrfs_cleanup_ordered_extents()
  and extent_clear_unlock_delalloc().

  btrfs_cleanup_ordered_extents() is safe even if we haven't created new
  ordered extent, in that case there should be no OE and that function
  will do nothing.

  The same applies to extent_clear_unlock_delalloc(), and since we're
  passing PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK, it
  will also clear folio dirty flag during error handling.

- Avoid touching the failed range of nocow_one_range()
  As the failed range will be cleaned up and unlocked by that function.

  Here we introduce a new variable @nocow_end to record the failed range,
  so that we can skip it during the error handling of run_delalloc_nocow().

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Qu Wenruo 2025-07-28 17:57:56 +09:30 committed by David Sterba
parent 6a378edc9a
commit 13141df705
1 changed files with 39 additions and 21 deletions
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60
fs/btrfs/inode.c
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@ -1982,8 +1982,8 @@ static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio
em = btrfs_create_io_em(inode, file_pos, &nocow_args->file_extent,
BTRFS_ORDERED_PREALLOC);
if (IS_ERR(em)) {
btrfs_unlock_extent(&inode->io_tree, file_pos, end, cached);
return PTR_ERR(em);
ret = PTR_ERR(em);
goto error;
}
btrfs_free_extent_map(em);
}
@ -1995,8 +1995,8 @@ static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio
if (IS_ERR(ordered)) {
if (is_prealloc)
btrfs_drop_extent_map_range(inode, file_pos, end, false);
btrfs_unlock_extent(&inode->io_tree, file_pos, end, cached);
return PTR_ERR(ordered);
ret = PTR_ERR(ordered);
goto error;
}
if (btrfs_is_data_reloc_root(inode->root))
@ -2008,23 +2008,25 @@ static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio
ret = btrfs_reloc_clone_csums(ordered);
btrfs_put_ordered_extent(ordered);
if (ret < 0)
goto error;
extent_clear_unlock_delalloc(inode, file_pos, end, locked_folio, cached,
EXTENT_LOCKED | EXTENT_DELALLOC |
EXTENT_CLEAR_DATA_RESV,
PAGE_UNLOCK | PAGE_SET_ORDERED);
/*
* 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, len);
btrfs_err(inode->root->fs_info,
"%s failed, root=%lld inode=%llu start=%llu len=%llu: %d",
__func__, btrfs_root_id(inode->root), btrfs_ino(inode),
file_pos, len, ret);
}
return ret;
error:
btrfs_cleanup_ordered_extents(inode, file_pos, len);
extent_clear_unlock_delalloc(inode, file_pos, end, locked_folio, cached,
EXTENT_LOCKED | EXTENT_DELALLOC |
EXTENT_CLEAR_DATA_RESV,
PAGE_UNLOCK | PAGE_START_WRITEBACK |
PAGE_END_WRITEBACK);
btrfs_err(inode->root->fs_info,
"%s failed, root=%lld inode=%llu start=%llu len=%llu: %d",
__func__, btrfs_root_id(inode->root), btrfs_ino(inode),
file_pos, len, ret);
return ret;
}
@ -2046,8 +2048,12 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
/*
* If not 0, represents the inclusive end of the last fallback_to_cow()
* range. Only for error handling.
*
* The same for nocow_end, it's to avoid double cleaning up the range
* already cleaned by nocow_one_range().
*/
u64 cow_end = 0;
u64 nocow_end = 0;
u64 cur_offset = start;
int ret;
bool check_prev = true;
@ -2222,8 +2228,10 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
&nocow_args, cur_offset,
extent_type == BTRFS_FILE_EXTENT_PREALLOC);
btrfs_dec_nocow_writers(nocow_bg);
if (ret < 0)
if (ret < 0) {
nocow_end = cur_offset + nocow_args.file_extent.num_bytes - 1;
goto error;
}
cur_offset = extent_end;
}
btrfs_release_path(path);
@ -2250,12 +2258,22 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
* start cur_offset end
* | OE cleanup | Untouched |
*
* We finished a fallback_to_cow() or nocow_one_range() call, but
* failed to check the next range.
* We finished a fallback_to_cow() or nocow_one_range() call,
* but failed to check the next range.
*
* or
* start cur_offset nocow_end end
* | OE cleanup | Skip | Untouched |
*
* nocow_one_range() failed, the range [cur_offset, nocow_end] is
* alread cleaned up.
*/
oe_cleanup_start = start;
oe_cleanup_len = cur_offset - start;
untouched_start = cur_offset;
if (nocow_end)
untouched_start = nocow_end + 1;
else
untouched_start = cur_offset;
untouched_len = end + 1 - untouched_start;
} else if (cow_start != (u64)-1 && cow_end == 0) {
/*