Re: [PATCH 1/2] btrfs: Abort transaction if btrfs_update_root fails in btrfs_ioctl_subvol_setflags

[David Sterba <dsterba@suse.cz>]

On Tue, Sep 26, 2017 at 05:27:41PM +0300, Nikolay Borisov wrote:
> btrfs_update_root can fail for any number of reasons, however the only error
> handling we do is to revert the modified flags, yet we do not abort the
> transaction but proceed to commit it.

AFAICS btrfs_update_root aborts the transaction itself, so it's not
needed in the caller.

> Fix this by explicitly checking if the
> update root routine has failed and abort the transaction.
> 
> Fixes: 0caa102da827 ("Btrfs: Add BTRFS_IOC_SUBVOL_GETFLAGS/SETFLAGS ioctls")
> Signed-off-by: Nikolay Borisov <nborisov@suse.com>
> ---
>  fs/btrfs/ioctl.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index d6715c2bcdc4..09fcd51f0e8c 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1842,8 +1842,11 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
>  
>  	ret = btrfs_update_root(trans, fs_info->tree_root,
>  				&root->root_key, &root->root_item);
> +	if (ret < 0)
> +		btrfs_abort_transaction(trans, ret);
>  
>  	btrfs_commit_transaction(trans);

I think the error from commit_transaction should be returned as well if
we get here.

So:

ret = btrfs_update_root();

if (ret < 0) {
	end_transaction();
	goto out_reset;
}

ret = btrfs_commit_transaction();

out_reset:
/* and then as it is */
if (ret)
	btrfs_set_root_flags(...);

etc.



> +
>  out_reset:
>  	if (ret)
>  		btrfs_set_root_flags(&root->root_item, root_flags);
> -- 
> 2.7.4
> 
> --
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