Btrfs: use a lock to protect incompat/compat flag of the super block
The following case will make the incompat/compat flag of the super block
be recovered.
Task1 |Task2
flags = btrfs_super_incompat_flags(); |
|flags = btrfs_super_incompat_flags();
flags |= new_flag1; |
|flags |= new_flag2;
btrfs_set_super_incompat_flags(flags); |
|btrfs_set_super_incompat_flags(flags);
the new_flag1 is recovered.
In order to avoid this problem, we introduce a lock named super_lock into
the btrfs_fs_info structure. If we want to update incompat/compat flags
of the super block, we must hold it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 5aa52ee..76ded9e 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3674,18 +3674,10 @@
static void check_raid56_incompat_flag(struct btrfs_fs_info *info, u64 type)
{
- u64 features;
-
if (!(type & (BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)))
return;
- features = btrfs_super_incompat_flags(info->super_copy);
- if (features & BTRFS_FEATURE_INCOMPAT_RAID56)
- return;
-
- features |= BTRFS_FEATURE_INCOMPAT_RAID56;
- btrfs_set_super_incompat_flags(info->super_copy, features);
- printk(KERN_INFO "btrfs: setting RAID5/6 feature flag\n");
+ btrfs_set_fs_incompat(info, RAID56);
}
static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,