btrfs: use memdup_user()

Remove open-coded memdup_user().

Note this changes some GFP_NOFS to GFP_KERNEL, since copy_from_user() may
cause pagefault, it's pointless to pass GFP_NOFS to kmalloc().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 9 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 9744af9d71e9..a7acfe639a44 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -635,14 +635,9 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
         if (!capable(CAP_SYS_ADMIN))
                 return -EPERM;
 
-        vol = kmalloc(sizeof(*vol), GFP_KERNEL);
-        if (!vol)
-                return -ENOMEM;
-
-        if (copy_from_user(vol, (void __user *)arg, sizeof(*vol))) {
-                ret = -EFAULT;
-                goto out;
-        }
+        vol = memdup_user((void __user *)arg, sizeof(*vol));
+        if (IS_ERR(vol))
+                return PTR_ERR(vol);
 
         switch (cmd) {
         case BTRFS_IOC_SCAN_DEV:
@@ -650,7 +645,7 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
                                             &btrfs_fs_type, &fs_devices);
                 break;
         }
-out:
+
         kfree(vol);
         return ret;
 }