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btrfs: factor out nocow ordered extent and extent map generation into a helper

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Currently we're doing all the ordered extent and extent map generation
inside a while() loop of run_delalloc_nocow().  This makes it pretty
hard to read, nor doing proper error handling.

So move that part of code into a helper, nocow_one_range().

This should not change anything, but there is a tiny timing change where
btrfs_dec_nocow_writers() is only called after nocow_one_range() helper
exits.

This timing change is small, and makes error handling easier, thus
should be fine.

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 13:53:41 +10:30
committed by David Sterba
parent ecde48a1a6
commit 10326fdcb3
1 changed files with 61 additions and 61 deletions
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122
fs/btrfs/inode.c
View File

@@ -1976,6 +1976,63 @@ static void cleanup_dirty_folios(struct btrfs_inode *inode,
mapping_set_error(mapping, error);
}
static int nocow_one_range(struct btrfs_inode *inode, struct folio *locked_folio,
struct extent_state **cached,
struct can_nocow_file_extent_args *nocow_args,
u64 file_pos, bool is_prealloc)
{
struct btrfs_ordered_extent *ordered;
u64 len = nocow_args->file_extent.num_bytes;
u64 end = file_pos + len - 1;
int ret = 0;
lock_extent(&inode->io_tree, file_pos, end, cached);
if (is_prealloc) {
struct extent_map *em;
em = btrfs_create_io_em(inode, file_pos, &nocow_args->file_extent,
BTRFS_ORDERED_PREALLOC);
if (IS_ERR(em)) {
unlock_extent(&inode->io_tree, file_pos, end, cached);
return PTR_ERR(em);
}
free_extent_map(em);
}
ordered = btrfs_alloc_ordered_extent(inode, file_pos, &nocow_args->file_extent,
is_prealloc
? (1 << BTRFS_ORDERED_PREALLOC)
: (1 << BTRFS_ORDERED_NOCOW));
if (IS_ERR(ordered)) {
if (is_prealloc)
btrfs_drop_extent_map_range(inode, file_pos, end, false);
unlock_extent(&inode->io_tree, file_pos, end, cached);
return PTR_ERR(ordered);
}
if (btrfs_is_data_reloc_root(inode->root))
/*
* Errors are handled later, as we must prevent
* extent_clear_unlock_delalloc() in error handler from freeing
* metadata of the created ordered extent.
*/
ret = btrfs_reloc_clone_csums(ordered);
btrfs_put_ordered_extent(ordered);
extent_clear_unlock_delalloc(inode, file_pos, end, locked_folio, cached,
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().
*/
return ret;
}
/*
* when nowcow writeback call back. This checks for snapshots or COW copies
* of the extents that exist in the file, and COWs the file as required.
@@ -2020,15 +2077,12 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
while (cur_offset <= end) {
struct btrfs_block_group *nocow_bg = NULL;
struct btrfs_ordered_extent *ordered;
struct btrfs_key found_key;
struct btrfs_file_extent_item *fi;
struct extent_buffer *leaf;
struct extent_state *cached_state = NULL;
u64 extent_end;
u64 nocow_end;
int extent_type;
bool is_prealloc;
ret = btrfs_lookup_file_extent(NULL, root, path, ino,
cur_offset, 0);
@@ -2162,67 +2216,13 @@ static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
}
}
nocow_end = cur_offset + nocow_args.file_extent.num_bytes - 1;
lock_extent(&inode->io_tree, cur_offset, nocow_end, &cached_state);
is_prealloc = extent_type == BTRFS_FILE_EXTENT_PREALLOC;
if (is_prealloc) {
struct extent_map *em;
em = btrfs_create_io_em(inode, cur_offset,
&nocow_args.file_extent,
BTRFS_ORDERED_PREALLOC);
if (IS_ERR(em)) {
unlock_extent(&inode->io_tree, cur_offset,
nocow_end, &cached_state);
btrfs_dec_nocow_writers(nocow_bg);
ret = PTR_ERR(em);
goto error;
}
free_extent_map(em);
}
ordered = btrfs_alloc_ordered_extent(inode, cur_offset,
&nocow_args.file_extent,
is_prealloc
? (1 << BTRFS_ORDERED_PREALLOC)
: (1 << BTRFS_ORDERED_NOCOW));
ret = nocow_one_range(inode, locked_folio, &cached_state,
&nocow_args, cur_offset,
extent_type == BTRFS_FILE_EXTENT_PREALLOC);
btrfs_dec_nocow_writers(nocow_bg);
if (IS_ERR(ordered)) {
if (is_prealloc) {
btrfs_drop_extent_map_range(inode, cur_offset,
nocow_end, false);
}
unlock_extent(&inode->io_tree, cur_offset,
nocow_end, &cached_state);
ret = PTR_ERR(ordered);
if (ret < 0)
goto error;
}
if (btrfs_is_data_reloc_root(root))
/*
* Error handled later, as we must prevent
* extent_clear_unlock_delalloc() in error handler
* from freeing metadata of created ordered extent.
*/
ret = btrfs_reloc_clone_csums(ordered);
btrfs_put_ordered_extent(ordered);
extent_clear_unlock_delalloc(inode, cur_offset, nocow_end,
locked_folio, &cached_state,
EXTENT_LOCKED | EXTENT_DELALLOC |
EXTENT_CLEAR_DATA_RESV,
PAGE_UNLOCK | PAGE_SET_ORDERED);
cur_offset = extent_end;
/*
* 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().
*/
if (ret)
goto error;
}
btrfs_release_path(path);