Add /dev/btrfs-control for device scanning ioctls

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 40 insertions, 1 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 4423a91206a1..67ed216df475 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -36,6 +36,7 @@
 #include <linux/parser.h>
 #include <linux/ctype.h>
 #include <linux/namei.h>
+#include <linux/miscdevice.h>
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
@@ -444,6 +445,13 @@ static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
         return 0;
 }
 
+static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
+                                unsigned long arg)
+{
+        printk("btrfs control ioctl %d\n", cmd);
+        return 0;
+}
+
 static struct file_system_type btrfs_fs_type = {
         .owner          = THIS_MODULE,
         .name           = "btrfs",
@@ -451,6 +459,7 @@ static struct file_system_type btrfs_fs_type = {
         .kill_sb        = kill_block_super,
         .fs_flags       = FS_REQUIRES_DEV,
 };
+
 static void btrfs_write_super_lockfs(struct super_block *sb)
 {
         struct btrfs_root *root = btrfs_sb(sb);
@@ -482,6 +491,30 @@ static struct super_operations btrfs_super_ops = {
         .write_super_lockfs = btrfs_write_super_lockfs,
         .unlockfs       = btrfs_unlockfs,
 };
+
+static const struct file_operations btrfs_ctl_fops = {
+        .unlocked_ioctl  = btrfs_control_ioctl,
+        .compat_ioctl = btrfs_control_ioctl,
+        .owner   = THIS_MODULE,
+};
+
+static struct miscdevice btrfs_misc = {
+        .minor          = MISC_DYNAMIC_MINOR,
+        .name           = "btrfs-control",
+        .fops           = &btrfs_ctl_fops
+};
+
+static int btrfs_interface_init(void)
+{
+        return misc_register(&btrfs_misc);
+}
+
+void btrfs_interface_exit(void)
+{
+        if (misc_deregister(&btrfs_misc) < 0)
+                printk("misc_deregister failed for control device");
+}
+
 static int __init init_btrfs_fs(void)
 {
         int err;
@@ -503,11 +536,16 @@ static int __init init_btrfs_fs(void)
         if (err)
                 goto free_extent_io;
 
-        err = register_filesystem(&btrfs_fs_type);
+        err = btrfs_interface_init();
         if (err)
                 goto free_extent_map;
+        err = register_filesystem(&btrfs_fs_type);
+        if (err)
+                goto unregister_ioctl;
         return 0;
 
+unregister_ioctl:
+        btrfs_interface_exit();
 free_extent_map:
         extent_map_exit();
 free_extent_io:
@@ -526,6 +564,7 @@ static void __exit exit_btrfs_fs(void)
         btrfs_destroy_cachep();
         extent_map_exit();
         extent_io_exit();
+        btrfs_interface_exit();
         unregister_filesystem(&btrfs_fs_type);
         btrfs_exit_sysfs();
 }