[PATCH V21 18/19] Btrfs: subpage-blocksize: __btrfs_lookup_bio_sums: Set offset when moving to a new bio_vec

[Chandan Rajendra <chandan@linux.vnet.ibm.com>]

In __btrfs_lookup_bio_sums() we set the file offset value at the
beginning of every iteration of the while loop. This is incorrect since
the blocks mapped by the current bvec->bv_page might not yet have been
completely processed.

This commit fixes the issue by setting the file offset value when we
move to the next bvec of the bio.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
---
 fs/btrfs/file-item.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index d0d571c..8fc09c1 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -222,11 +222,11 @@ static int __btrfs_lookup_bio_sums(struct btrfs_root *root,
 	disk_bytenr = (u64)bio->bi_iter.bi_sector << 9;
 	if (dio)
 		offset = logical_offset;
+	else
+		offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 
 	page_bytes_left = bvec->bv_len;
 	while (bio_index < bio->bi_vcnt) {
-		if (!dio)
-			offset = page_offset(bvec->bv_page) + bvec->bv_offset;
 		count = btrfs_find_ordered_sum(inode, offset, disk_bytenr,
 					       (u32 *)csum, nblocks);
 		if (count)
@@ -301,6 +301,9 @@ found:
 					goto done;
 				}
 				bvec++;
+				if (!dio)
+					offset = page_offset(bvec->bv_page)
+						+ bvec->bv_offset;
 				page_bytes_left = bvec->bv_len;
 			}
 
-- 
2.5.5