Btrfs: avoid stack bloat in btrfs_ioctl_fs_info()

The size of struct btrfs_ioctl_fs_info_args is as big as 1KB, so
don't declare the variable on stack.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Reviewed-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index ac37040..b793d11 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2054,29 +2054,34 @@ static long btrfs_ioctl_rm_dev(struct btrfs_root *root, void __user *arg)
 
 static long btrfs_ioctl_fs_info(struct btrfs_root *root, void __user *arg)
 {
-       struct btrfs_ioctl_fs_info_args fi_args;
+       struct btrfs_ioctl_fs_info_args *fi_args;
        struct btrfs_device *device;
        struct btrfs_device *next;
        struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
+       int ret = 0;
 
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
 
-       fi_args.num_devices = fs_devices->num_devices;
-       fi_args.max_id = 0;
-       memcpy(&fi_args.fsid, root->fs_info->fsid, sizeof(fi_args.fsid));
+       fi_args = kzalloc(sizeof(*fi_args), GFP_KERNEL);
+       if (!fi_args)
+               return -ENOMEM;
+
+       fi_args->num_devices = fs_devices->num_devices;
+       memcpy(&fi_args->fsid, root->fs_info->fsid, sizeof(fi_args->fsid));
 
        mutex_lock(&fs_devices->device_list_mutex);
        list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
-               if (device->devid > fi_args.max_id)
-                       fi_args.max_id = device->devid;
+               if (device->devid > fi_args->max_id)
+                       fi_args->max_id = device->devid;
        }
        mutex_unlock(&fs_devices->device_list_mutex);
 
-       if (copy_to_user(arg, &fi_args, sizeof(fi_args)))
-               return -EFAULT;
+       if (copy_to_user(arg, fi_args, sizeof(*fi_args)))
+               ret = -EFAULT;
 
-       return 0;
+       kfree(fi_args);
+       return ret;
 }
 
 static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg)