[RFC PATCH V6 2/1] Btrfs: Add a new ioctl to get the label of a mounted file system
From: Jeff Liu <hidden>
Date: 2012-12-18 03:06:14
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
Introduce a new ioctl BTRFS_IOC_GET_FSLABEL to fetch the label of a mounted file system. Signed-off-by: Jie Liu <redacted> Signed-off-by: Anand Jain <redacted> Reviewed-by: Miao Xie <redacted> --- fs/btrfs/ioctl.c | 15 +++++++++++++++ fs/btrfs/ioctl.h | 2 ++ 2 files changed, 17 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 8fcf9a5..6a2488a 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c@@ -3699,6 +3699,19 @@ 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; + int ret; + + mutex_lock(&root->fs_info->volume_mutex); + ret = copy_to_user(arg, label, strlen(label)); + 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 +3810,8 @@ 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