btrfs: fix file_offset for REQ_BTRFS_ONE_ORDERED bios that get split

If a bio gets split, it needs to have a proper file_offset for checksum
validation and repair to work properly.

Based on feedback from Josef, commit 852eee62 ("btrfs: allow
btrfs_submit_bio to split bios") skipped this adjustment for ONE_ORDERED
bios.  But if we actually ever need to split a ONE_ORDERED read bio, this
will lead to a wrong file offset in the repair code.  Right now the only
user of the file_offset is logging of an error message so this is mostly
harmless, but the wrong offset might be more problematic for additional
users in the future.

Fixes: 852eee62 ("btrfs: allow btrfs_submit_bio to split bios")
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/bio.c

@@ -81,8 +81,7 @@ static struct btrfs_bio *btrfs_split_bio(struct btrfs_fs_info *fs_info,
 	btrfs_bio_init(bbio, fs_info, NULL, orig_bbio);
 	bbio->inode = orig_bbio->inode;
 	bbio->file_offset = orig_bbio->file_offset;
-	if (!(orig_bbio->bio.bi_opf & REQ_BTRFS_ONE_ORDERED))
-		orig_bbio->file_offset += map_length;
+	orig_bbio->file_offset += map_length;
 
 	atomic_inc(&orig_bbio->pending_ios);
 	return bbio;