[PATCH v3 03/18] btrfs: use correct bio size for error message in btrfs_end_dio_bio()

[Qu Wenruo <wqu@suse.com>]

At endio time, bio->bi_iter is no longer valid (there are some cases
they are still valid, but never ensured).

Thus if we really want to get the full size of bio, we have to iterate
them.

In btrfs_end_dio_bio() when we hit error, we would grab bio size from
bi_iter which can be wrong.

Fix it by iterating the bvecs and calculate the bio size.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/inode.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index dded46291637..dbcb4ae9e06d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -7866,12 +7866,19 @@ static void btrfs_end_dio_bio(struct bio *bio)
 	struct btrfs_dio_private *dip = bio->bi_private;
 	blk_status_t err = bio->bi_status;
 
-	if (err)
+	if (err) {
+		struct bvec_iter_all iter_all;
+		struct bio_vec *bvec;
+		u32 bi_size = 0;
+
+		bio_for_each_segment_all(bvec, bio, iter_all)
+			bi_size += bvec->bv_len;
+
 		btrfs_warn(BTRFS_I(dip->inode)->root->fs_info,
 			   "direct IO failed ino %llu rw %d,%u sector %#Lx len %u err no %d",
 			   btrfs_ino(BTRFS_I(dip->inode)), bio_op(bio),
-			   bio->bi_opf, bio->bi_iter.bi_sector,
-			   bio->bi_iter.bi_size, err);
+			   bio->bi_opf, bio->bi_iter.bi_sector, bi_size, err);
+	}
 
 	if (bio_op(bio) == REQ_OP_READ)
 		err = btrfs_check_read_dio_bio(dip, btrfs_bio(bio), !err);
-- 
2.35.1