btrfs: return proper mapped length for RAID56 profiles in __btrfs_map_block()

For profiles other than RAID56, __btrfs_map_block() returns @map_length
as min(stripe_end, logical + *length), which is also the same result
from btrfs_get_io_geometry().

But for RAID56, __btrfs_map_block() returns @map_length as stripe_len.

This strange behavior is going to hurt incoming bio split at
btrfs_map_bio() time, as we will use @map_length as bio split size.

Fix this behavior by returning @map_length by the same calculation as
for other profiles.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 36a5466..2eb72dd 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6471,7 +6471,10 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info,
                        num_stripes = map->num_stripes;
                        max_errors = btrfs_chunk_max_errors(map);
 
-                       *length = map->stripe_len;
+                       /* Return the length to the full stripe end */
+                       *length = min(logical + *length,
+                                     raid56_full_stripe_start + em->start +
+                                     data_stripes * stripe_len) - logical;
                        stripe_index = 0;
                        stripe_offset = 0;
                } else {