From: Qu Wenruo <wqu@suse.com>
Date: Fri, 17 Jun 2022 10:04:06 +0000 (+0200)
Subject: btrfs: return proper mapped length for RAID56 profiles in __btrfs_map_block()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=462b0b2a86c4d5a902812a449f99722e65c6cc66;p=linux.git

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 36a5466266c41..2eb72dda764c2 100644
--- 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 {