releases/4.5.7/btrfs-add-write-protection-to-set_features-ioctl.patch

   1 From 7ab19625a911f7568ec85302e3aa7a64186006c8 Mon Sep 17 00:00:00 2001
   2 From: David Sterba <dsterba@suse.cz>
   3 Date: Wed, 4 May 2016 11:32:00 +0200
   4 Subject: btrfs: add write protection to SET_FEATURES ioctl
   5
   6 From: David Sterba <dsterba@suse.cz>
   7
   8 commit 7ab19625a911f7568ec85302e3aa7a64186006c8 upstream.
   9
  10 Perform the want_write check if we get far enough to do any writes.
  11
  12 Signed-off-by: David Sterba <dsterba@suse.com>
  13 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  14
  15 ---
  16  fs/btrfs/ioctl.c |   16 +++++++++++++---
  17  1 file changed, 13 insertions(+), 3 deletions(-)
  18
  19 --- a/fs/btrfs/ioctl.c
  20 +++ b/fs/btrfs/ioctl.c
  21 @@ -5397,9 +5397,15 @@ static int btrfs_ioctl_set_features(stru
  22         if (ret)
  23                 return ret;
  24
  25 +       ret = mnt_want_write_file(file);
  26 +       if (ret)
  27 +               return ret;
  28 +
  29         trans = btrfs_start_transaction(root, 0);
  30 -       if (IS_ERR(trans))
  31 -               return PTR_ERR(trans);
  32 +       if (IS_ERR(trans)) {
  33 +               ret = PTR_ERR(trans);
  34 +               goto out_drop_write;
  35 +       }
  36
  37         spin_lock(&root->fs_info->super_lock);
  38         newflags = btrfs_super_compat_flags(super_block);
  39 @@ -5418,7 +5424,11 @@ static int btrfs_ioctl_set_features(stru
  40         btrfs_set_super_incompat_flags(super_block, newflags);
  41         spin_unlock(&root->fs_info->super_lock);
  42
  43 -       return btrfs_commit_transaction(trans, root);
  44 +       ret = btrfs_commit_transaction(trans, root);
  45 +out_drop_write:
  46 +       mnt_drop_write_file(file);
  47 +
  48 +       return ret;
  49  }
  50
  51  long btrfs_ioctl(struct file *file, unsigned int