From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:55472 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756568Ab3AHTq5 (ORCPT ); Tue, 8 Jan 2013 14:46:57 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r08Jkvk7016664 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 8 Jan 2013 14:46:57 -0500 Message-ID: <50EC77B0.3050400@redhat.com> Date: Tue, 08 Jan 2013 13:46:56 -0600 From: Eric Sandeen MIME-Version: 1.0 To: Zach Brown CC: linux-btrfs@vger.kernel.org Subject: Re: [PATCH] btrfs: fix btrfs_cont_expand() freeing IS_ERR em References: <1357673878-25591-1-git-send-email-zab@redhat.com> In-Reply-To: <1357673878-25591-1-git-send-email-zab@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 1/8/13 1:37 PM, Zach Brown wrote: > btrfs_cont_expand() tries to free an IS_ERR em as it gets an error from > btrfs_get_extent() and breaks out of its loop. > > An instance of -EEXIST was reported in the wild: > > https://bugzilla.redhat.com/show_bug.cgi?id=874407 > > I have no idea if that -EEXIST is surprising, or not. Regardless, this > error handling should be cleaned up to handle other reasonable errors > (ENOMEM, EIO; whatever). > > This seemed to be the only buggy freeing of the relatively rare IS_ERR > em so I opted to fix the caller rather than teach free_extent_map() to > use IS_ERR_OR_NULL(). > > Signed-off-by: Zach Brown Looks good (maybe IS_ERR_OR_NULL would be more future-proof, but *shrug*) Reviewed-by: Eric Sandeen > --- > fs/btrfs/inode.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index edd30ae..0bc7bb3 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -3690,6 +3690,7 @@ int btrfs_cont_expand(struct inode *inode, loff_t oldsize, loff_t size) > block_end - cur_offset, 0); > if (IS_ERR(em)) { > err = PTR_ERR(em); > + em = NULL; > break; > } > last_byte = min(extent_map_end(em), block_end); >