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Commit ee17fc80 authored by David Sterba's avatar David Sterba
Browse files

btrfs: sysfs: protect reading label by lock 



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: default avatarDavid Sterba <dsterba@suse.com>
parent 66ac9fe7

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,