On Thu, Apr 11, 2013 at 06:30:16PM +0800, Miao Xie wrote:
> 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.
>
> + /*
> + * Used to protect the incompat_flags, compat_flags, compat_ro_flags
> + * when they are updated.
> + spinlock_t super_lock;
The lock name is too general for protecting just *_flags, do you have
plans to add more items from superblock under this lock? If no, I
suggest to pick a different name.
> @@ -3663,8 +3674,15 @@ static inline void __btrfs_set_fs_incompat(struct btrfs_fs_info *fs_info,
> disk_super = fs_info->super_copy;
> features = btrfs_super_incompat_flags(disk_super);
> if (!(features & flag)) {
> - features |= flag;
> - btrfs_set_super_incompat_flags(disk_super, features);
> + spin_lock(&fs_info->super_lock);
> + features = btrfs_super_incompat_flags(disk_super);
> + if (!(features & flag)) {
> + features |= flag;
> + btrfs_set_super_incompat_flags(disk_super, features);
> + printk(KERN_INFO "btrfs: setting %llu feature flag\n",
> + flag);
flag is u64, please use (unsigned long long)flag and possibly the new
btrfs_info replacement of printks.
> + }
> + spin_unlock(&fs_info->super_lock);
> }
> }
otherwise ok.
Reviewed-by: David Sterba <dsterba@xxxxxxx>
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