From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavel Shilovsky , Jeff Layton , Steve French Subject: [ 02/72] CIFS: Fix a deadlock when a file is reopened Date: Thu, 18 Jul 2013 22:25:19 -0700 Message-Id: <20130719052600.022992619@linuxfoundation.org> In-Reply-To: <20130719052559.852627424@linuxfoundation.org> References: <20130719052559.852627424@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-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: Greg Kroah-Hartman --- fs/cifs/file.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- a/fs/cifs/file.c +++ b/fs/cifs/file.c @@ -553,11 +553,10 @@ cifs_relock_file(struct cifsFileInfo *cf 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; } @@ -568,7 +567,7 @@ cifs_relock_file(struct cifsFileInfo *cf else rc = tcon->ses->server->ops->push_mand_locks(cfile); - up_write(&cinode->lock_sem); + up_read(&cinode->lock_sem); return rc; }