[PATCH V4 10/45] btrfs: avoid to access bvec table directly for a cloned bio

From: Ming Lei
Date: Mon Dec 18 2017 - 07:40:00 EST


Commit 17347cec15f919901c90(Btrfs: change how we iterate bios in endio)
mentioned that for dio the submitted bio may be fast cloned, we
can't access the bvec table directly for a cloned bio, so use
bio_get_first_bvec() to retrieve the 1st bvec.

Cc: Chris Mason <clm@xxxxxx>
Cc: Josef Bacik <jbacik@xxxxxx>
Cc: David Sterba <dsterba@xxxxxxxx>
Cc: linux-btrfs@xxxxxxxxxxxxxxx
Cc: Liu Bo <bo.li.liu@xxxxxxxxxx>
Reviewed-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
Acked: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
fs/btrfs/inode.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4d5cb6e93c80..cb1e2d201434 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8015,6 +8015,7 @@ static blk_status_t dio_read_error(struct inode *inode, struct bio *failed_bio,
int segs;
int ret;
blk_status_t status;
+ struct bio_vec bvec;

BUG_ON(bio_op(failed_bio) == REQ_OP_WRITE);

@@ -8030,8 +8031,9 @@ static blk_status_t dio_read_error(struct inode *inode, struct bio *failed_bio,
}

segs = bio_segments(failed_bio);
+ bio_get_first_bvec(failed_bio, &bvec);
if (segs > 1 ||
- (failed_bio->bi_io_vec->bv_len > btrfs_inode_sectorsize(inode)))
+ (bvec.bv_len > btrfs_inode_sectorsize(inode)))
read_mode |= REQ_FAILFAST_DEV;

isector = start - btrfs_io_bio(failed_bio)->logical;
--
2.9.5