From a8bfd4abea3da0e28f215e2a2b8c2f1ca27ebe80 Mon Sep 17 00:00:00 2001
From: "jeff.liu" <jeff.liu@oracle.com>
Date: Sat, 5 Jan 2013 02:48:08 +0000
Subject: [PATCH] Btrfs: set/change the label of a mounted file system
With this new ioctl(2) BTRFS_IOC_SET_FSLABEL, we can set/change the label of a mounted file system.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Goffredo Baroncelli <kreijack@inwind.it>
Reviewed-by: David Sterba <dsterba@suse.cz>
Reviewed-by: Goffredo Baroncelli <kreijack@inwind.it>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
---
fs/btrfs/ioctl.c | 42 ++++++++++++++++++++++++++++++++++++++
include/uapi/linux/btrfs.h | 2 ++
2 files changed, 44 insertions(+)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index fcc15a6804a9b..0f68729f261e4 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3936,6 +3936,46 @@ static int btrfs_ioctl_get_fslabel(struct file *file, void __user *arg)
return ret ? -EFAULT : 0;
}
+static int btrfs_ioctl_set_fslabel(struct file *file, void __user *arg)
+{
+ struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
+ struct btrfs_super_block *super_block = root->fs_info->super_copy;
+ struct btrfs_trans_handle *trans;
+ char label[BTRFS_LABEL_SIZE];
+ int ret;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (copy_from_user(label, arg, sizeof(label)))
+ return -EFAULT;
+
+ if (strnlen(label, BTRFS_LABEL_SIZE) == BTRFS_LABEL_SIZE) {
+ pr_err("btrfs: unable to set label with more than %d bytes\n",
+ BTRFS_LABEL_SIZE - 1);
+ return -EINVAL;
+ }
+
+ ret = mnt_want_write_file(file);
+ if (ret)
+ return ret;
+
+ mutex_lock(&root->fs_info->volume_mutex);
+ trans = btrfs_start_transaction(root, 0);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ goto out_unlock;
+ }
+
+ strcpy(super_block->label, label);
+ ret = btrfs_end_transaction(trans, root);
+
+out_unlock:
+ mutex_unlock(&root->fs_info->volume_mutex);
+ mnt_drop_write_file(file);
+ return ret;
+}
+
long btrfs_ioctl(struct file *file, unsigned int
cmd, unsigned long arg)
{
@@ -4038,6 +4078,8 @@ long btrfs_ioctl(struct file *file, unsigned int
return btrfs_ioctl_dev_replace(root, argp);
case BTRFS_IOC_GET_FSLABEL:
return btrfs_ioctl_get_fslabel(file, argp);
+ case BTRFS_IOC_SET_FSLABEL:
+ return btrfs_ioctl_set_fslabel(file, argp);
}
return -ENOTTY;
diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index 51c0b335e0c88..fa3a5f9338fc5 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -504,6 +504,8 @@ struct btrfs_ioctl_send_args {
struct btrfs_ioctl_qgroup_limit_args)
#define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \
char[BTRFS_LABEL_SIZE])
+#define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 50, \
+ 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, \
--
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