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btrfs: remove the io_pages field in struct extent_buffer 

No need to track the number of pages under I/O now that each
extent_buffer is read and written using a single bio.  For the
read side we need to grab an extra reference for the duration of
the I/O to prevent eviction, though.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Christoph Hellwig 2023-05-03 17:24:36 +02:00 committed by David Sterba
parent 31d89399da
commit 113fa05c2f
2 changed files with 5 additions and 13 deletions
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17
fs/btrfs/extent_io.c
View File

@ -1767,8 +1767,6 @@ static void extent_buffer_write_end_io(struct btrfs_bio *bbio)
struct page *page = bvec->bv_page;
u32 len = bvec->bv_len;
atomic_dec(&eb->io_pages);
if (!uptodate) {
btrfs_page_clear_uptodate(fs_info, page, start, len);
btrfs_page_set_error(fs_info, page, start, len);
@ -1791,7 +1789,6 @@ static void prepare_eb_write(struct extent_buffer *eb)
unsigned long end;
clear_bit(EXTENT_BUFFER_WRITE_ERR, &eb->bflags);
atomic_set(&eb->io_pages, num_extent_pages(eb));
/* Set btree blocks beyond nritems with 0 to avoid stale content */
nritems = btrfs_header_nritems(eb);
@ -3235,8 +3232,7 @@ static void __free_extent_buffer(struct extent_buffer *eb)
static int extent_buffer_under_io(const struct extent_buffer *eb)
{
return (atomic_read(&eb->io_pages) ||
test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
return (test_bit(EXTENT_BUFFER_WRITEBACK, &eb->bflags) ||
test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags));
}
@ -3372,7 +3368,6 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
spin_lock_init(&eb->refs_lock);
atomic_set(&eb->refs, 1);
atomic_set(&eb->io_pages, 0);
ASSERT(len <= BTRFS_MAX_METADATA_BLOCKSIZE);
@ -3489,9 +3484,9 @@ static void check_buffer_tree_ref(struct extent_buffer *eb)
* adequately protected by the refcount, but the TREE_REF bit and
* its corresponding reference are not. To protect against this
* class of races, we call check_buffer_tree_ref from the codepaths
* which trigger io after they set eb->io_pages. Note that once io is
* initiated, TREE_REF can no longer be cleared, so that is the
* moment at which any such race is best fixed.
* which trigger io. Note that once io is initiated, TREE_REF can no
* longer be cleared, so that is the moment at which any such race is
* best fixed.
*/
refs = atomic_read(&eb->refs);
if (refs >= 2 && test_bit(EXTENT_BUFFER_TREE_REF, &eb->bflags))
@ -4062,7 +4057,6 @@ static void extent_buffer_read_end_io(struct btrfs_bio *bbio)
struct bio_vec *bvec;
u32 bio_offset = 0;
atomic_inc(&eb->refs);
eb->read_mirror = bbio->mirror_num;
if (uptodate &&
@ -4077,7 +4071,6 @@ static void extent_buffer_read_end_io(struct btrfs_bio *bbio)
}
bio_for_each_segment_all(bvec, &bbio->bio, iter_all) {
atomic_dec(&eb->io_pages);
end_page_read(bvec->bv_page, uptodate, eb->start + bio_offset,
bvec->bv_len);
bio_offset += bvec->bv_len;
@ -4100,8 +4093,8 @@ static void __read_extent_buffer_pages(struct extent_buffer *eb, int mirror_num,
clear_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
eb->read_mirror = 0;
atomic_set(&eb->io_pages, num_pages);
check_buffer_tree_ref(eb);
atomic_inc(&eb->refs);
bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
REQ_OP_READ | REQ_META, eb->fs_info,

1
fs/btrfs/extent_io.h
View File

@ -79,7 +79,6 @@ struct extent_buffer {
struct btrfs_fs_info *fs_info;
spinlock_t refs_lock;
atomic_t refs;
atomic_t io_pages;
int read_mirror;
struct rcu_head rcu_head;
pid_t lock_owner;