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btrfs: update some folio related comments

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Remove references to the page lock and page->mapping.  Also btrfs folios
can never be swizzled into swap (mentioned in extent_write_cache_pages()).

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Matthew Wilcox (Oracle) 2025-01-21 05:40:50 +00:00 committed by David Sterba
parent 96b2854de8
commit b9967834ab
3 changed files with 5 additions and 7 deletions
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8
fs/btrfs/extent_io.c
View File

@ -2192,10 +2192,8 @@ static int extent_write_cache_pages(struct address_space *mapping,
done_index = folio_next_index(folio);
/*
* At this point we hold neither the i_pages lock nor
* the page lock: the page may be truncated or
* invalidated (changing page->mapping to NULL),
* or even swizzled back from swapper_space to
* tmpfs file mapping
* the folio lock: the folio may be truncated or
* invalidated (changing folio->mapping to NULL).
*/
if (!folio_trylock(folio)) {
submit_write_bio(bio_ctrl, 0);
@ -3233,7 +3231,7 @@ struct extent_buffer *alloc_extent_buffer(struct btrfs_fs_info *fs_info,
}
/*
* Now all pages of that extent buffer is unmapped, set UNMAPPED flag,
* so it can be cleaned up without utilizing page->mapping.
* so it can be cleaned up without utilizing folio->mapping.
*/
set_bit(EXTENT_BUFFER_UNMAPPED, &eb->bflags);

2
fs/btrfs/inode.c
View File

@ -2896,7 +2896,7 @@ int btrfs_writepage_cow_fixup(struct folio *folio)
* We are already holding a reference to this inode from
* write_cache_pages. We need to hold it because the space reservation
* takes place outside of the folio lock, and we can't trust
* page->mapping outside of the folio lock.
* folio->mapping outside of the folio lock.
*/
ihold(inode);
btrfs_folio_set_checked(fs_info, folio, folio_pos(folio), folio_size(folio));

2
fs/btrfs/subpage.c
View File

@ -72,7 +72,7 @@ bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space
/*
* Only data pages (either through DIO or compression) can have no
* mapping. And if page->mapping->host is data inode, it's subpage.
* mapping. And if mapping->host is data inode, it's subpage.
* As we have ruled our sectorsize >= PAGE_SIZE case already.
*/
if (!mapping || !mapping->host || is_data_inode(BTRFS_I(mapping->host)))