[PATCH 1/2] btrfs: fix direct I/O read repair for split bios

Christoph Hellwig
2022-03-24T16:06:43Z

When a bio is split in btrfs_submit_direct, dip->file_offset contains
the file offset for the first bio. But this means the start value used
in btrfs_check_read_dio_bio is incorrect for subsequent bios. Add
a file_offset field to struct btrfs_bio to pass along the correct offset.

Given that check_data_csum only uses start of an error message this
means problems with this miscalculation will only show up when I/O
fails or checksums mismatch.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Qu Wenruo <wqu@suse.com>
---
fs/btrfs/extent_io.c | 1 +
fs/btrfs/inode.c | 13 +++++--------
fs/btrfs/volumes.h | 3 +++
3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index d78b3a2d04e3b..c50d3a1225086 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2658,6 +2658,7 @@ int btrfs_repair_one_sector(struct inode *inode,

repair_bio = btrfs_bio_alloc(1);
repair_bbio = btrfs_bio(repair_bio);
+ repair_bbio->file_offset = start;
repair_bio->bi_opf = REQ_OP_READ;
repair_bio->bi_end_io = failed_bio->bi_end_io;
repair_bio->bi_iter.bi_sector = failrec->logical >> 9;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index aa0a60ee26cb7..762133fac0df1 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7805,8 +7805,6 @@ static blk_status_t btrfs_check_read_dio_bio(struct btrfs_dio_private *dip,
const bool csum = !(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM);
struct bio_vec bvec;
struct bvec_iter iter;
- const u64 orig_file_offset = dip->file_offset;
- u64 start = orig_file_offset;
u32 bio_offset = 0;
blk_status_t err = BLK_STS_OK;

@@ -7816,6 +7814,8 @@ static blk_status_t btrfs_check_read_dio_bio(struct btrfs_dio_private *dip,
nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info, bvec.bv_len);
pgoff = bvec.bv_offset;
for (i = 0; i < nr_sectors; i++) {
+ u64 start = bbio->file_offset + bio_offset;
+
ASSERT(pgoff < PAGE_SIZE);
if (uptodate &&
(!csum || !check_data_csum(inode, bbio,
@@ -7828,17 +7828,13 @@ static blk_status_t btrfs_check_read_dio_bio(struct btrfs_dio_private *dip,
} else {
int ret;

- ASSERT((start - orig_file_offset) < UINT_MAX);
- ret = btrfs_repair_one_sector(inode,
- &bbio->bio,
- start - orig_file_offset,
- bvec.bv_page, pgoff,
+ ret = btrfs_repair_one_sector(inode, &bbio->bio,
+ bio_offset, bvec.bv_page, pgoff,
start, bbio->mirror_num,
submit_dio_repair_bio);
if (ret)
err = errno_to_blk_status(ret);
}
- start += sectorsize;
ASSERT(bio_offset + sectorsize > bio_offset);
bio_offset += sectorsize;
pgoff += sectorsize;
@@ -8041,6 +8037,7 @@ static void btrfs_submit_direct(const struct iomap_iter *iter,
bio = btrfs_bio_clone_partial(dio_bio, clone_offset, clone_len);
bio->bi_private = dip;
bio->bi_end_io = btrfs_end_dio_bio;
+ btrfs_bio(bio)->file_offset = file_offset;

if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
status = extract_ordered_extent(BTRFS_I(inode), bio,
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index bd297f23d19e7..f3e28f11cfb6e 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -328,6 +328,9 @@ struct btrfs_fs_devices {
struct btrfs_bio {
unsigned int mirror_num;

+ /* for direct I/O */
+ u64 file_offset;
+
/* @device is for stripe IO submission. */
struct btrfs_device *device;
u8 *csum;
--
2.30.2