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btrfs: use a separate end_io handler for read_extent_buffer

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Now that we always use a single bio to read an extent_buffer, the buffer
can be passed to the end_io handler as private data.  This allows
implementing a much simplified dedicated end I/O handler for metadata
reads.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Christoph Hellwig 2023-05-03 17:24:28 +02:00 committed by David Sterba
parent e194931076
commit 046b562b20
3 changed files with 41 additions and 149 deletions
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105
fs/btrfs/disk-io.c
View file

@ -427,8 +427,8 @@ static int check_tree_block_fsid(struct extent_buffer *eb)
}
/* Do basic extent buffer checks at read time */
static int validate_extent_buffer(struct extent_buffer *eb,
struct btrfs_tree_parent_check *check)
int btrfs_validate_extent_buffer(struct extent_buffer *eb,
struct btrfs_tree_parent_check *check)
{
struct btrfs_fs_info *fs_info = eb->fs_info;
u64 found_start;
@ -541,107 +541,6 @@ static int validate_extent_buffer(struct extent_buffer *eb,
return ret;
}
static int validate_subpage_buffer(struct page *page, u64 start, u64 end,
int mirror, struct btrfs_tree_parent_check *check)
{
struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
struct extent_buffer *eb;
bool reads_done;
int ret = 0;
ASSERT(check);
/*
* We don't allow bio merge for subpage metadata read, so we should
* only get one eb for each endio hook.
*/
ASSERT(end == start + fs_info->nodesize - 1);
ASSERT(PagePrivate(page));
eb = find_extent_buffer(fs_info, start);
/*
* When we are reading one tree block, eb must have been inserted into
* the radix tree. If not, something is wrong.
*/
ASSERT(eb);
reads_done = atomic_dec_and_test(&eb->io_pages);
/* Subpage read must finish in page read */
ASSERT(reads_done);
eb->read_mirror = mirror;
if (test_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags)) {
ret = -EIO;
goto err;
}
ret = validate_extent_buffer(eb, check);
if (ret < 0)
goto err;
set_extent_buffer_uptodate(eb);
free_extent_buffer(eb);
return ret;
err:
/*
* end_bio_extent_readpage decrements io_pages in case of error,
* make sure it has something to decrement.
*/
atomic_inc(&eb->io_pages);
clear_extent_buffer_uptodate(eb);
free_extent_buffer(eb);
return ret;
}
int btrfs_validate_metadata_buffer(struct btrfs_bio *bbio,
struct page *page, u64 start, u64 end,
int mirror)
{
struct extent_buffer *eb;
int ret = 0;
int reads_done;
ASSERT(page->private);
if (btrfs_sb(page->mapping->host->i_sb)->nodesize < PAGE_SIZE)
return validate_subpage_buffer(page, start, end, mirror,
&bbio->parent_check);
eb = (struct extent_buffer *)page->private;
/*
* The pending IO might have been the only thing that kept this buffer
* in memory. Make sure we have a ref for all this other checks
*/
atomic_inc(&eb->refs);
reads_done = atomic_dec_and_test(&eb->io_pages);
if (!reads_done)
goto err;
eb->read_mirror = mirror;
if (test_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags)) {
ret = -EIO;
goto err;
}
ret = validate_extent_buffer(eb, &bbio->parent_check);
if (!ret)
set_extent_buffer_uptodate(eb);
err:
if (ret) {
/*
* our io error hook is going to dec the io pages
* again, we have to make sure it has something
* to decrement
*/
atomic_inc(&eb->io_pages);
clear_extent_buffer_uptodate(eb);
}
free_extent_buffer(eb);
return ret;
}
#ifdef CONFIG_MIGRATION
static int btree_migrate_folio(struct address_space *mapping,
struct folio *dst, struct folio *src, enum migrate_mode mode)

5
fs/btrfs/disk-io.h
View file

@ -82,9 +82,8 @@ void btrfs_btree_balance_dirty(struct btrfs_fs_info *fs_info);
void btrfs_btree_balance_dirty_nodelay(struct btrfs_fs_info *fs_info);
void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
struct btrfs_root *root);
int btrfs_validate_metadata_buffer(struct btrfs_bio *bbio,
struct page *page, u64 start, u64 end,
int mirror);
int btrfs_validate_extent_buffer(struct extent_buffer *eb,
struct btrfs_tree_parent_check *check);
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
struct btrfs_root *btrfs_alloc_dummy_root(struct btrfs_fs_info *fs_info);
#endif

80
fs/btrfs/extent_io.c
View file

@ -663,35 +663,6 @@ static void begin_page_read(struct btrfs_fs_info *fs_info, struct page *page)
btrfs_subpage_start_reader(fs_info, page, page_offset(page), PAGE_SIZE);
}
/*
* Find extent buffer for a givne bytenr.
*
* This is for end_bio_extent_readpage(), thus we can't do any unsafe locking
* in endio context.
*/
static struct extent_buffer *find_extent_buffer_readpage(
struct btrfs_fs_info *fs_info, struct page *page, u64 bytenr)
{
struct extent_buffer *eb;
/*
* For regular sectorsize, we can use page->private to grab extent
* buffer
*/
if (fs_info->nodesize >= PAGE_SIZE) {
ASSERT(PagePrivate(page) && page->private);
return (struct extent_buffer *)page->private;
}
/* For subpage case, we need to lookup buffer radix tree */
rcu_read_lock();
eb = radix_tree_lookup(&fs_info->buffer_radix,
bytenr >> fs_info->sectorsize_bits);
rcu_read_unlock();
ASSERT(eb);
return eb;
}
/*
* after a readpage IO is done, we need to:
* clear the uptodate bits on error
@ -713,7 +684,6 @@ static void end_bio_extent_readpage(struct btrfs_bio *bbio)
* larger than UINT_MAX, u32 here is enough.
*/
u32 bio_offset = 0;
int mirror;
struct bvec_iter_all iter_all;
ASSERT(!bio_flagged(bio, BIO_CLONED));
@ -753,11 +723,6 @@ static void end_bio_extent_readpage(struct btrfs_bio *bbio)
end = start + bvec->bv_len - 1;
len = bvec->bv_len;
mirror = bbio->mirror_num;
if (uptodate && !is_data_inode(inode) &&
btrfs_validate_metadata_buffer(bbio, page, start, end, mirror))
uptodate = false;
if (likely(uptodate)) {
loff_t i_size = i_size_read(inode);
pgoff_t end_index = i_size >> PAGE_SHIFT;
@ -778,13 +743,6 @@ static void end_bio_extent_readpage(struct btrfs_bio *bbio)
zero_user_segment(page, zero_start,
offset_in_page(end) + 1);
}
} else if (!is_data_inode(inode)) {
struct extent_buffer *eb;
eb = find_extent_buffer_readpage(fs_info, page, start);
set_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
eb->read_mirror = mirror;
atomic_dec(&eb->io_pages);
}
/* Update page status and unlock. */
@ -4221,6 +4179,42 @@ void set_extent_buffer_uptodate(struct extent_buffer *eb)
}
}
static void extent_buffer_read_end_io(struct btrfs_bio *bbio)
{
struct extent_buffer *eb = bbio->private;
bool uptodate = !bbio->bio.bi_status;
struct bvec_iter_all iter_all;
struct bio_vec *bvec;
u32 bio_offset = 0;
atomic_inc(&eb->refs);
eb->read_mirror = bbio->mirror_num;
if (uptodate &&
btrfs_validate_extent_buffer(eb, &bbio->parent_check) < 0)
uptodate = false;
if (uptodate) {
set_extent_buffer_uptodate(eb);
} else {
clear_extent_buffer_uptodate(eb);
set_bit(EXTENT_BUFFER_READ_ERR, &eb->bflags);
}
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;
}
unlock_extent(&bbio->inode->io_tree, eb->start,
eb->start + bio_offset - 1, NULL);
free_extent_buffer(eb);
bio_put(&bbio->bio);
}
static void __read_extent_buffer_pages(struct extent_buffer *eb, int mirror_num,
struct btrfs_tree_parent_check *check)
{
@ -4234,7 +4228,7 @@ static void __read_extent_buffer_pages(struct extent_buffer *eb, int mirror_num,
bbio = btrfs_bio_alloc(INLINE_EXTENT_BUFFER_PAGES,
REQ_OP_READ | REQ_META, eb->fs_info,
end_bio_extent_readpage, NULL);
extent_buffer_read_end_io, eb);
bbio->bio.bi_iter.bi_sector = eb->start >> SECTOR_SHIFT;
bbio->inode = BTRFS_I(eb->fs_info->btree_inode);
bbio->file_offset = eb->start;