btrfs: Refactor btrfs_merge_bio_hook

This function really checks whether adding more data to the bio will
straddle a stripe/chunk. So first let's give it a more appropraite name
- btrfs_bio_fits_in_stripe. Secondly, the offset parameter was never
used to just remove it. Thirdly, pages are submitted to either btree or
data inodes so it's guaranteed that tree->ops is set so replace the
check with an ASSERT. Finally, document the parameters of the function.
No functional changes.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2085d4d3a6fe..6c806808b6a1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6136,8 +6136,10 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
 		*length = em->len - offset;
 	}
 
-	/* This is for when we're called from btrfs_merge_bio_hook() and all
-	   it cares about is the length */
+	/*
+	 * This is for when we're called from btrfs_bio_fits_in_stripe and all
+	 * it cares about is the length
+	 */
 	if (!bbio_ret)
 		goto out;