From patchwork Wed Jul 17 22:47:44 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 259825 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 26E2D2C0098 for ; Thu, 18 Jul 2013 08:52:46 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UzaaO-0007Pq-B9; Wed, 17 Jul 2013 22:52:40 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UzaYZ-0006en-EA for kernel-team@lists.ubuntu.com; Wed, 17 Jul 2013 22:50:47 +0000 Received: from c-67-160-231-162.hsd1.ca.comcast.net ([67.160.231.162] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UzaWh-0008Fy-OT; Wed, 17 Jul 2013 22:48:52 +0000 Received: from kamal by fourier with local (Exim 4.80) (envelope-from ) id 1UzaWf-0002VO-Gu; Wed, 17 Jul 2013 15:48:49 -0700 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 132/145] CIFS: Fix a deadlock when a file is reopened Date: Wed, 17 Jul 2013 15:47:44 -0700 Message-Id: <1374101277-7915-133-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1374101277-7915-1-git-send-email-kamal@canonical.com> References: <1374101277-7915-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Cc: Steve French , Kamal Mostafa , Pavel Shilovsky X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.8.13.5 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Pavel Shilovsky commit 689c3db4d57a73bee6c5ad7797fce7b54d32a87c upstream. If we request reading or writing on a file that needs to be reopened, it causes the deadlock: we are already holding rw semaphore for reading and then we try to acquire it for writing in cifs_relock_file. Fix this by acquiring the semaphore for reading in cifs_relock_file due to we don't make any changes in locks and don't need a write access. Signed-off-by: Pavel Shilovsky Acked-by: Jeff Layton Signed-off-by: Steve French Signed-off-by: Kamal Mostafa --- fs/cifs/file.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/fs/cifs/file.c b/fs/cifs/file.c index 1d93ee8..ae62632 100644 --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -551,11 +551,10 @@ cifs_relock_file(struct cifsFileInfo *cfile) struct cifs_tcon *tcon = tlink_tcon(cfile->tlink); int rc = 0; - /* we are going to update can_cache_brlcks here - need a write access */ - down_write(&cinode->lock_sem); + down_read(&cinode->lock_sem); if (cinode->can_cache_brlcks) { - /* can cache locks - no need to push them */ - up_write(&cinode->lock_sem); + /* can cache locks - no need to relock */ + up_read(&cinode->lock_sem); return rc; } @@ -566,7 +565,7 @@ cifs_relock_file(struct cifsFileInfo *cfile) else rc = tcon->ses->server->ops->push_mand_locks(cfile); - up_write(&cinode->lock_sem); + up_read(&cinode->lock_sem); return rc; }