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

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

Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Anand 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: Josef Bacik <jbacik@fusionio.com>
This commit is contained in:
jeff.liu 2013-01-05 02:48:01 +00:00 committed by Josef Bacik
parent 569e0f358c
commit 867ab667e7
2 changed files with 23 additions and 0 deletions
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21
fs/btrfs/ioctl.c
View File

@ -3917,6 +3917,25 @@ out:
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;

2
include/uapi/linux/btrfs.h
View File

@ -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, \