Add a new ioctl(2) BTRFS_IOC_GET_FSLABLE, so that we can get the label upon a mounted file system.
Signed-off-by: Jie Liu <jeff....@oracle.com> Signed-off-by: Anand Jain <anand.j...@oracle.com> Cc: Miao Xie <mi...@cn.fujitsu.com> Cc: Goffredo Baroncelli <kreij...@inwind.it> Cc: David Sterba <dste...@suse.cz> --- fs/btrfs/ioctl.c | 22 ++++++++++++++++++++++ fs/btrfs/ioctl.h | 2 ++ 2 files changed, 24 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 8fcf9a5..4be5d15 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -3699,6 +3699,26 @@ 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) { + len--; + WARN(1, "btrfs: device label is not zero terminated, " + "it will be truncated to %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) { @@ -3797,6 +3817,8 @@ long btrfs_ioctl(struct file *file, unsigned int return btrfs_ioctl_qgroup_create(root, argp); case BTRFS_IOC_QGROUP_LIMIT: return btrfs_ioctl_qgroup_limit(root, argp); + case BTRFS_IOC_GET_FSLABEL: + return btrfs_ioctl_get_fslabel(file, argp); } return -ENOTTY; diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h index 731e287..5b2cbef 100644 --- a/fs/btrfs/ioctl.h +++ b/fs/btrfs/ioctl.h @@ -451,6 +451,8 @@ 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) #endif -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html