Commit f8ba9c11 authored by Jeff Mahoney's avatar Jeff Mahoney Committed by Chris Mason
Browse files

btrfs: publish fs label in sysfs 



This adds a writeable attribute which describes the label.

Signed-off-by: default avatarJeff Mahoney <jeffm@suse.com>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent 29e5be24

fs/btrfs/sysfs.c

+44 −0
Original line number Diff line number Diff line
@@ -355,6 +355,49 @@ static const struct attribute *allocation_attrs[] = { 
	NULL,

};



static ssize_t btrfs_label_show(struct kobject *kobj,

				struct kobj_attribute *a, char *buf)

{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);

	return snprintf(buf, PAGE_SIZE, "%s\n", fs_info->super_copy->label);

}



static ssize_t btrfs_label_store(struct kobject *kobj,

				 struct kobj_attribute *a,

				 const char *buf, size_t len)

{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);

	struct btrfs_trans_handle *trans;

	struct btrfs_root *root = fs_info->fs_root;

	int ret;



	if (len >= BTRFS_LABEL_SIZE) {

		pr_err("btrfs: unable to set label with more than %d bytes\n",

		       BTRFS_LABEL_SIZE - 1);

		return -EINVAL;

	}



	trans = btrfs_start_transaction(root, 0);

	if (IS_ERR(trans))

		return PTR_ERR(trans);



	spin_lock(&root->fs_info->super_lock);

	strcpy(fs_info->super_copy->label, buf);

	spin_unlock(&root->fs_info->super_lock);

	ret = btrfs_commit_transaction(trans, root);



	if (!ret)

		return len;



	return ret;

}

BTRFS_ATTR_RW(label, 0644, btrfs_label_show, btrfs_label_store);



static struct attribute *btrfs_attrs[] = {

	BTRFS_ATTR_PTR(label),

	NULL,

};



static void btrfs_release_super_kobj(struct kobject *kobj)

{

	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
@@ -364,6 +407,7 @@ static void btrfs_release_super_kobj(struct kobject *kobj) 
static struct kobj_type btrfs_ktype = {

	.sysfs_ops	= &kobj_sysfs_ops,

	.release	= btrfs_release_super_kobj,

	.default_attrs	= btrfs_attrs,

};



static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)