If the label setting ioctl races with sysfs label handler, we could get
mixed result in the output, part old part new. We should either get the
old or new label. The chances to hit this race are low.
Signed-off-by: David Sterba <dste...@suse.com>
---
fs/btrfs/sysfs.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 3d14618ce54b..7b0da1dcb6df 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -367,7 +367,12 @@ static ssize_t btrfs_label_show(struct kobject *kobj,
{
struct btrfs_fs_info *fs_info = to_fs_info(kobj);
char *label = fs_info->super_copy->label;
- return snprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label);
+
+ spin_lock(&fs_info->super_lock);
+ snprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label);
+ spin_unlock(&fs_info->super_lock);
+
+ return buf;
}
static ssize_t btrfs_label_store(struct kobject *kobj,
--
2.7.1
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