[PATCH 2/2] [Repost] btrfslabel - kernel space

[Goffredo Baroncelli]

This is the second patch, the one kernel related. This patch introduces two new
ioctls to read and change the label of a btrfs filesystem.

This patch is a repost of a previous patch of Morey Roof.

If request I can modify the patch. Comments are welcome.

BR
G.Baroncelli

---
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 645a179..18f3ada 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1301,6 +1301,53 @@ long btrfs_ioctl_trans_end(struct file *file)
        return 0;
 }
 
+long btrfs_ioctl_set_label(struct btrfs_root *root, void __user *arg)
+{
+       struct btrfs_trans_handle *trans;
+       struct btrfs_ioctl_label_args *label_args;
+       int ret = 0;
+
+       label_args = kmalloc(sizeof(*label_args), GFP_NOFS);
+
+       if (!label_args)
+               return -ENOMEM;
+
+       if (copy_from_user(label_args, arg, sizeof(*label_args)))
+       {
+               ret = -EFAULT;
+       } else
+       {
+               /* Everything looks good, so lets do a label change */
+               label_args->name[BTRFS_LABEL_SIZE] = 0x00;
+               trans = btrfs_start_transaction(root, 1);
+               strncpy(root->fs_info->super_copy.label, label_args->name, 
BTRFS_LABEL_SIZE);
+               btrfs_commit_transaction(trans, root);
+       }
+
+       kfree(label_args);
+       return ret;
+}
+
+long btrfs_ioctl_get_label(struct btrfs_root *root, void __user *arg)
+{
+       struct btrfs_ioctl_label_args *label_args;
+       int ret = 0;
+
+       label_args = kmalloc(sizeof(*label_args), GFP_NOFS);
+
+       if (!label_args)
+               return -ENOMEM;
+
+       strncpy(label_args->name, root->fs_info->super_copy.label, 
BTRFS_LABEL_SIZE);
+       if (copy_to_user(arg, label_args, sizeof(*label_args)))
+       {
+               ret = -EFAULT;
+       }
+
+       kfree(label_args);
+       return ret;
+}
+
 long btrfs_ioctl(struct file *file, unsigned int
                cmd, unsigned long arg)
 {
@@ -1338,6 +1385,10 @@ long btrfs_ioctl(struct file *file, unsigned int
                return btrfs_ioctl_trans_start(file);
        case BTRFS_IOC_TRANS_END:
                return btrfs_ioctl_trans_end(file);
+       case BTRFS_IOC_SET_LABEL:
+               return btrfs_ioctl_set_label(root, (void __user *)arg);
+       case BTRFS_IOC_GET_LABEL:
+               return btrfs_ioctl_get_label(root, (void __user *)arg);
        case BTRFS_IOC_SYNC:
                btrfs_sync_fs(file->f_dentry->d_sb, 1);
                return 0;
diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h
index bc49914..995756d 100644
--- a/fs/btrfs/ioctl.h
+++ b/fs/btrfs/ioctl.h
@@ -19,6 +19,7 @@
 #ifndef __IOCTL_
 #define __IOCTL_
 #include <linux/ioctl.h>
+#include "ctree.h"
 
 #define BTRFS_IOCTL_MAGIC 0x94
 #define BTRFS_VOL_NAME_MAX 255
@@ -30,6 +31,10 @@ struct btrfs_ioctl_vol_args {
        char name[BTRFS_PATH_NAME_MAX + 1];
 };
 
+struct btrfs_ioctl_label_args {
+       char name[BTRFS_LABEL_SIZE + 1];
+};
+
 struct btrfs_ioctl_clone_range_args {
   __s64 src_fd;
   __u64 src_offset, src_length;
@@ -67,4 +72,11 @@ struct btrfs_ioctl_clone_range_args {
                                   struct btrfs_ioctl_vol_args)
 #define BTRFS_IOC_SNAP_DESTROY _IOW(BTRFS_IOCTL_MAGIC, 15, \
                                struct btrfs_ioctl_vol_args)
+
+/* Used to set and get the current volume label */
+#define BTRFS_IOC_SET_LABEL    _IOW(BTRFS_IOCTL_MAGIC, 16, \
+                               struct btrfs_ioctl_label_args)
+#define BTRFS_IOC_GET_LABEL    _IOW(BTRFS_IOCTL_MAGIC, 17, \
+                               struct btrfs_ioctl_label_args)
+
 #endif

---

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