6.12-stable review patch. If anyone has any objections, please let me know.
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From: Qu Wenruo wqu@suse.com
[ Upstream commit 336e69f3025fb70db9d0dfb7f36ac79887bf5341 ]
Since commit d7172f52e993 ("btrfs: use per-buffer locking for extent_buffer reading"), metadata read no longer relies on the subpage reader locking.
This means we do not need to maintain a different metadata/data split for locking, so we can convert the existing reader lock users by:
- add_ra_bio_pages() Convert to btrfs_folio_set_writer_lock()
- end_folio_read() Convert to btrfs_folio_end_writer_lock()
- begin_folio_read() Convert to btrfs_folio_set_writer_lock()
- folio_range_has_eb() Remove the subpage->readers checks, since it is always 0.
- Remove btrfs_subpage_start_reader() and btrfs_subpage_end_reader()
Signed-off-by: Qu Wenruo wqu@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Stable-dep-of: 8bf334beb349 ("btrfs: fix double accounting race when extent_writepage_io() failed") Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/compression.c | 3 +- fs/btrfs/extent_io.c | 10 ++----- fs/btrfs/subpage.c | 62 ++---------------------------------------- fs/btrfs/subpage.h | 13 --------- 4 files changed, 5 insertions(+), 83 deletions(-)
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 90aef2627ca27..64eaf74fbebc8 100644 --- a/fs/btrfs/compression.c +++ b/fs/btrfs/compression.c @@ -545,8 +545,7 @@ static noinline int add_ra_bio_pages(struct inode *inode, * subpage::readers and to unlock the page. */ if (fs_info->sectorsize < PAGE_SIZE) - btrfs_subpage_start_reader(fs_info, folio, cur, - add_size); + btrfs_folio_set_writer_lock(fs_info, folio, cur, add_size); folio_put(folio); cur += add_size; } diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 8222ae6f29af5..5d6b3b812593d 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -438,7 +438,7 @@ static void end_folio_read(struct folio *folio, bool uptodate, u64 start, u32 le if (!btrfs_is_subpage(fs_info, folio->mapping)) folio_unlock(folio); else - btrfs_subpage_end_reader(fs_info, folio, start, len); + btrfs_folio_end_writer_lock(fs_info, folio, start, len); }
/* @@ -495,7 +495,7 @@ static void begin_folio_read(struct btrfs_fs_info *fs_info, struct folio *folio) return;
ASSERT(folio_test_private(folio)); - btrfs_subpage_start_reader(fs_info, folio, folio_pos(folio), PAGE_SIZE); + btrfs_folio_set_writer_lock(fs_info, folio, folio_pos(folio), PAGE_SIZE); }
/* @@ -2507,12 +2507,6 @@ static bool folio_range_has_eb(struct btrfs_fs_info *fs_info, struct folio *foli subpage = folio_get_private(folio); if (atomic_read(&subpage->eb_refs)) return true; - /* - * Even there is no eb refs here, we may still have - * end_folio_read() call relying on page::private. - */ - if (atomic_read(&subpage->readers)) - return true; } return false; } diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c index 99341e98bbcc7..0587a7d7b5e81 100644 --- a/fs/btrfs/subpage.c +++ b/fs/btrfs/subpage.c @@ -140,12 +140,10 @@ struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info, return ERR_PTR(-ENOMEM);
spin_lock_init(&ret->lock); - if (type == BTRFS_SUBPAGE_METADATA) { + if (type == BTRFS_SUBPAGE_METADATA) atomic_set(&ret->eb_refs, 0); - } else { - atomic_set(&ret->readers, 0); + else atomic_set(&ret->writers, 0); - } return ret; }
@@ -221,62 +219,6 @@ static void btrfs_subpage_assert(const struct btrfs_fs_info *fs_info, __start_bit; \ })
-void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, - struct folio *folio, u64 start, u32 len) -{ - struct btrfs_subpage *subpage = folio_get_private(folio); - const int start_bit = subpage_calc_start_bit(fs_info, folio, locked, start, len); - const int nbits = len >> fs_info->sectorsize_bits; - unsigned long flags; - - - btrfs_subpage_assert(fs_info, folio, start, len); - - spin_lock_irqsave(&subpage->lock, flags); - /* - * Even though it's just for reading the page, no one should have - * locked the subpage range. - */ - ASSERT(bitmap_test_range_all_zero(subpage->bitmaps, start_bit, nbits)); - bitmap_set(subpage->bitmaps, start_bit, nbits); - atomic_add(nbits, &subpage->readers); - spin_unlock_irqrestore(&subpage->lock, flags); -} - -void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, - struct folio *folio, u64 start, u32 len) -{ - struct btrfs_subpage *subpage = folio_get_private(folio); - const int start_bit = subpage_calc_start_bit(fs_info, folio, locked, start, len); - const int nbits = len >> fs_info->sectorsize_bits; - unsigned long flags; - bool is_data; - bool last; - - btrfs_subpage_assert(fs_info, folio, start, len); - is_data = is_data_inode(BTRFS_I(folio->mapping->host)); - - spin_lock_irqsave(&subpage->lock, flags); - - /* The range should have already been locked. */ - ASSERT(bitmap_test_range_all_set(subpage->bitmaps, start_bit, nbits)); - ASSERT(atomic_read(&subpage->readers) >= nbits); - - bitmap_clear(subpage->bitmaps, start_bit, nbits); - last = atomic_sub_and_test(nbits, &subpage->readers); - - /* - * For data we need to unlock the page if the last read has finished. - * - * And please don't replace @last with atomic_sub_and_test() call - * inside if () condition. - * As we want the atomic_sub_and_test() to be always executed. - */ - if (is_data && last) - folio_unlock(folio); - spin_unlock_irqrestore(&subpage->lock, flags); -} - static void btrfs_subpage_clamp_range(struct folio *folio, u64 *start, u32 *len) { u64 orig_start = *start; diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h index 6289d6f65b87d..8488ea057b30b 100644 --- a/fs/btrfs/subpage.h +++ b/fs/btrfs/subpage.h @@ -45,14 +45,6 @@ enum { struct btrfs_subpage { /* Common members for both data and metadata pages */ spinlock_t lock; - /* - * Both data and metadata needs to track how many readers are for the - * page. - * Data relies on @readers to unlock the page when last reader finished. - * While metadata doesn't need page unlock, it needs to prevent - * page::private get cleared before the last end_page_read(). - */ - atomic_t readers; union { /* * Structures only used by metadata @@ -95,11 +87,6 @@ void btrfs_free_subpage(struct btrfs_subpage *subpage); void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio); void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
-void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info, - struct folio *folio, u64 start, u32 len); -void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, - struct folio *folio, u64 start, u32 len); - void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info, struct folio *folio, u64 start, u32 len); void btrfs_folio_set_writer_lock(const struct btrfs_fs_info *fs_info,