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Commit 867ab667 authored by jeff.liu's avatar jeff.liu Committed by Josef Bacik
Browse files

Btrfs: Add a new ioctl to get the label of a mounted file system 



Add a new ioctl(2) BTRFS_IOC_GET_FSLABLE, so that we can get the label upon a mounted filesystem.

Signed-off-by: default avatarJie Liu <jeff.liu@oracle.com>
Signed-off-by: default avatarAnand Jain <anand.jain@oracle.com>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: Goffredo Baroncelli <kreijack@inwind.it>
Cc: David Sterba <dsterba@suse.cz>
Signed-off-by: default avatarJosef Bacik <jbacik@fusionio.com>
parent 569e0f35

fs/btrfs/ioctl.c

+21 −0
Original line number Diff line number Diff line
@@ -3917,6 +3917,25 @@ static long btrfs_ioctl_set_received_subvol(struct file *file, 
	return ret;

}



static int btrfs_ioctl_get_fslabel(struct file *file, void __user *arg)

{

	struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;

	const char *label = root->fs_info->super_copy->label;

	size_t len = strnlen(label, BTRFS_LABEL_SIZE);

	int ret;



	if (len == BTRFS_LABEL_SIZE) {

		pr_warn("btrfs: label is too long, return the first %zu bytes\n",

			--len);

	}



	mutex_lock(&root->fs_info->volume_mutex);

	ret = copy_to_user(arg, label, len);

	mutex_unlock(&root->fs_info->volume_mutex);



	return ret ? -EFAULT : 0;

}



long btrfs_ioctl(struct file *file, unsigned int

		cmd, unsigned long arg)

{
@@ -4017,6 +4036,8 @@ long btrfs_ioctl(struct file *file, unsigned int 
		return btrfs_ioctl_qgroup_limit(file, argp);

	case BTRFS_IOC_DEV_REPLACE:

		return btrfs_ioctl_dev_replace(root, argp);

	case BTRFS_IOC_GET_FSLABEL:

		return btrfs_ioctl_get_fslabel(file, argp);

	}



	return -ENOTTY;

include/uapi/linux/btrfs.h

+2 −0
Original line number Diff line number Diff line
@@ -502,6 +502,8 @@ struct btrfs_ioctl_send_args { 
			       struct btrfs_ioctl_qgroup_create_args)

#define BTRFS_IOC_QGROUP_LIMIT _IOR(BTRFS_IOCTL_MAGIC, 43, \

			       struct btrfs_ioctl_qgroup_limit_args)

#define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \

				   char[BTRFS_LABEL_SIZE])

#define BTRFS_IOC_GET_DEV_STATS _IOWR(BTRFS_IOCTL_MAGIC, 52, \

				      struct btrfs_ioctl_get_dev_stats)

#define BTRFS_IOC_DEV_REPLACE _IOWR(BTRFS_IOCTL_MAGIC, 53, \