btrfs: sysfs: protect reading label by lock (ee17fc80) · Commits · 戴 / test

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 <dsterba@suse.com>

fs/btrfs/sysfs.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -367,7 +367,13 @@ 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);
		ssize_t ret;

		spin_lock(&fs_info->super_lock);
		ret = snprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label);
		spin_unlock(&fs_info->super_lock);

		return ret;
		}

		static ssize_t btrfs_label_store(struct kobject *kobj,

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