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btrfs: use iosize while reading compressed pages

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While using compression, a submitted bio is mapped with a compressed bio
which performs the read from disk, decompresses and returns uncompressed
data to original bio. The original bio must reflect the uncompressed
size (iosize) of the I/O to be performed, or else the page just gets the
decompressed I/O length of data (disk_io_size). The compressed bio
checks the extent map and gets the correct length while performing the
I/O from disk.

This came up in subpage work when only compressed length of the original
bio was filled in the page. This worked correctly for pagesize ==
sectorsize because both compressed and uncompressed data are at pagesize
boundaries, and would end up filling the requested page.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Goldwyn Rodrigues 2020-09-15 10:41:40 -05:00 committed by David Sterba
parent eefa45f593
commit 949b32732e
1 changed files with 3 additions and 7 deletions
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10
fs/btrfs/extent_io.c
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@ -3158,7 +3158,6 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
int nr = 0;
size_t pg_offset = 0;
size_t iosize;
size_t disk_io_size;
size_t blocksize = inode->i_sb->s_blocksize;
unsigned long this_bio_flag = 0;
struct extent_io_tree *tree = &BTRFS_I(inode)->io_tree;
@ -3224,13 +3223,10 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
iosize = min(extent_map_end(em) - cur, end - cur + 1);
cur_end = min(extent_map_end(em) - 1, end);
iosize = ALIGN(iosize, blocksize);
if (this_bio_flag & EXTENT_BIO_COMPRESSED) {
disk_io_size = em->block_len;
if (this_bio_flag & EXTENT_BIO_COMPRESSED)
offset = em->block_start;
} else {
else
offset = em->block_start + extent_offset;
disk_io_size = iosize;
}
block_start = em->block_start;
if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
block_start = EXTENT_MAP_HOLE;
@ -3319,7 +3315,7 @@ int btrfs_do_readpage(struct page *page, struct extent_map **em_cached,
}
ret = submit_extent_page(REQ_OP_READ | read_flags, NULL,
page, offset, disk_io_size,
page, offset, iosize,
pg_offset, bio,
end_bio_extent_readpage, 0,
*bio_flags,