From: Filipe Manana <fdmanana@suse.com>
Date: Tue, 8 Jan 2019 11:42:01 +0000 (+0000)
Subject: Btrfs: do not overwrite error return value in the balance ioctl
X-Git-Tag: v5.1-rc1~138^2~72
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d00c2d9c76975d70089418dc1447b51da3a6a118;p=users%2Fjedix%2Flinux-maple.git

Btrfs: do not overwrite error return value in the balance ioctl

If the call to btrfs_balance() failed we would overwrite the error
returned to user space with -EFAULT if the call to copy_to_user() failed
as well. Fix that by calling copy_to_user() only if btrfs_balance()
returned success or was canceled.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index b07b19acdbb1..c21cc408556d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4781,7 +4781,7 @@ do_balance:
 	ret = btrfs_balance(fs_info, bctl, bargs);
 	bctl = NULL;
 
-	if (arg) {
+	if ((ret == 0 || ret == -ECANCELED) && arg) {
 		if (copy_to_user(arg, bargs, sizeof(*bargs)))
 			ret = -EFAULT;
 	}