From patchwork Fri May 7 14:03:51 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 51914 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.samba.org (fn.samba.org [216.83.154.106]) by ozlabs.org (Postfix) with ESMTP id E8246B7D5E for ; Sat, 8 May 2010 00:02:54 +1000 (EST) Received: from fn.samba.org (localhost [127.0.0.1]) by lists.samba.org (Postfix) with ESMTP id A8404AD2F2; Fri, 7 May 2010 08:02:54 -0600 (MDT) X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on fn.samba.org X-Spam-Level: X-Spam-Status: No, score=-9.6 required=3.8 tests=AWL, BAYES_00, RCVD_IN_DNSWL_HI, SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.2.5 X-Original-To: linux-cifs-client@lists.samba.org Delivered-To: linux-cifs-client@lists.samba.org Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by lists.samba.org (Postfix) with ESMTP id 9B431ACFC9 for ; Fri, 7 May 2010 08:02:48 -0600 (MDT) Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o47E2k7W028485 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 7 May 2010 10:02:46 -0400 Received: from localhost.localdomain (vpn2-10-172.ams2.redhat.com [10.36.10.172]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id o47E2hpn024460; Fri, 7 May 2010 10:02:44 -0400 From: Jeff Layton To: linux-cifs-client@lists.samba.org Date: Fri, 7 May 2010 16:03:51 +0200 Message-Id: <1273241032-6404-1-git-send-email-jlayton@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.12 Cc: smfrench@gmail.com Subject: [linux-cifs-client] [PATCH] cifs: guard against hardlinking directories X-BeenThere: linux-cifs-client@lists.samba.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: The Linux CIFS VFS client List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-cifs-client-bounces@lists.samba.org Errors-To: linux-cifs-client-bounces@lists.samba.org When we made serverino the default, we trusted that the field sent by the server in the "uniqueid" field was actually unique. It turns out that it isn't reliably so. Samba, in particular, will just put the st_ino in the uniqueid field when unix extensions are enabled. When a share spans multiple filesystems, it's quite possible that there will be collisions. This is a server bug, but when the inodes in question are a directory (as is often the case) and there is a collision with the root inode of the mount, the result is a kernel panic on umount. Fix this by checking explicitly for directory inodes with the same uniqueid. If that is the case, then we can assume that using server inode numbers will be a problem and that they should be disabled. Signed-off-by: Jeff Layton --- fs/cifs/cifsglob.h | 1 + fs/cifs/inode.c | 21 +++++++++++++++++++-- 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h index ecf0ffb..0c2fd17 100644 --- a/fs/cifs/cifsglob.h +++ b/fs/cifs/cifsglob.h @@ -502,6 +502,7 @@ struct dfs_info3_param { #define CIFS_FATTR_DFS_REFERRAL 0x1 #define CIFS_FATTR_DELETE_PENDING 0x2 #define CIFS_FATTR_NEED_REVAL 0x4 +#define CIFS_FATTR_INO_COLLISION 0x8 struct cifs_fattr { u32 cf_flags; diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c index ee35c97..fb20f11 100644 --- a/fs/cifs/inode.c +++ b/fs/cifs/inode.c @@ -714,6 +714,16 @@ cifs_find_inode(struct inode *inode, void *opaque) if (CIFS_I(inode)->uniqueid != fattr->cf_uniqueid) return 0; + /* + * uh oh -- it's a directory. We can't use it since hardlinked dirs are + * verboten. Disable serverino and return it as if it were found, the + * caller can discard it, generate a uniqueid and retry the find + */ + if (S_ISDIR(inode->i_mode)) { + fattr->cf_flags |= CIFS_FATTR_INO_COLLISION; + cifs_autodisable_serverino(CIFS_SB(inode->i_sb)); + } + return 1; } @@ -733,15 +743,22 @@ cifs_iget(struct super_block *sb, struct cifs_fattr *fattr) unsigned long hash; struct inode *inode; +retry_iget5_locked: cFYI(1, ("looking for uniqueid=%llu", fattr->cf_uniqueid)); /* hash down to 32-bits on 32-bit arch */ hash = cifs_uniqueid_to_ino_t(fattr->cf_uniqueid); inode = iget5_locked(sb, hash, cifs_find_inode, cifs_init_inode, fattr); - - /* we have fattrs in hand, update the inode */ if (inode) { + /* was there a problematic inode number collision? */ + if (fattr->cf_flags & CIFS_FATTR_INO_COLLISION) { + iput(inode); + fattr->cf_uniqueid = iunique(sb, ROOT_I); + fattr->cf_flags &= ~CIFS_FATTR_INO_COLLISION; + goto retry_iget5_locked; + } + cifs_fattr_to_inode(inode, fattr); if (sb->s_flags & MS_NOATIME) inode->i_flags |= S_NOATIME | S_NOCMTIME;