Btrfs: fix allocation size calculations in alloc_btrfs_bio

Since commit 8e5cfb55d3f (Btrfs: Make raid_map array be inlined in
btrfs_bio structure), the raid map array is allocated along with the
btrfs bio in alloc_btrfs_bio.  The calculation used to decide how much
we need to allocate was using the wrong parameter passed into the
allocation function.

The passed in real_stripes will be zero if a target replace operation
is not currently running.  We want to use total_stripes instead.

Signed-off-by: Chris Mason <clm@fb.com>
Reported-by: David Sterba <dsterba@suse.cz>
Tested-by: David Sterba <dsterba@suse.cz>

1 files changed, 8 insertions, 1 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index cd4d1315aaa9..8222f6f74147 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4903,10 +4903,17 @@ static void sort_parity_stripes(struct btrfs_bio *bbio, int num_stripes)
 static struct btrfs_bio *alloc_btrfs_bio(int total_stripes, int real_stripes)
 {
         struct btrfs_bio *bbio = kzalloc(
+                 /* the size of the btrfs_bio */
                 sizeof(struct btrfs_bio) +
+                /* plus the variable array for the stripes */
                 sizeof(struct btrfs_bio_stripe) * (total_stripes) +
+                /* plus the variable array for the tgt dev */
                 sizeof(int) * (real_stripes) +
-                sizeof(u64) * (real_stripes),
+                /*
+                 * plus the raid_map, which includes both the tgt dev
+                 * and the stripes
+                 */
+                sizeof(u64) * (total_stripes),
                 GFP_NOFS);
         if (!bbio)
                 return NULL;