From: Chuck Lever Subject: [PATCH 18/27] NFS: Prevent nfs_getattr() hang during heavy write workloads Date: Fri, 26 Oct 2007 13:32:13 -0400 Message-ID: <20071026173213.31475.72792.stgit@manray.1015granger.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: nfs@lists.sourceforge.net To: trond.myklebust@fys.uio.no Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list2-new.sourceforge.net with esmtp (Exim 4.43) id 1IlT35-0007LK-JQ for nfs@lists.sourceforge.net; Fri, 26 Oct 2007 10:32:45 -0700 Received: from flpi185.sbcis.sbc.com ([207.115.20.187] helo=flpi185.prodigy.net) by mail.sourceforge.net with esmtp (Exim 4.44) id 1IlT2v-0006QR-AL for nfs@lists.sourceforge.net; Fri, 26 Oct 2007 10:32:35 -0700 List-Id: "Discussion of NFS under Linux development, interoperability, and testing." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfs-bounces@lists.sourceforge.net Errors-To: nfs-bounces@lists.sourceforge.net POSIX requires that ctime and mtime, as reported by the stat(2) call, reflect the activity of the most recent write(2). To that end, nfs_getattr() flushes pending dirty writes to a file before doing a GETATTR to allow the NFS server to set the file's size, ctime, and mtime properly. However, nfs_getattr() can be starved when a constant stream of application writes to a file prevents nfs_wb_nocommit() from completing. This usually results in hangs of programs doing a stat against an NFS file that is being written. "ls -l" is a common victim of this behavior. To prevent starvation, hold the file's i_mutex in nfs_getattr() to freeze applications writes temporarily so the client can more quickly obtain clean values for a file's size, mtime, and ctime. Signed-off-by: Chuck Lever --- fs/nfs/inode.c | 13 +++++++++++-- 1 files changed, 11 insertions(+), 2 deletions(-) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index cd0e57f..cc3a09d 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -461,9 +461,18 @@ int nfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) int need_atime = NFS_I(inode)->cache_validity & NFS_INO_INVALID_ATIME; int err; - /* Flush out writes to the server in order to update c/mtime */ - if (S_ISREG(inode->i_mode)) + /* + * Flush out writes to the server in order to update c/mtime. + * + * Hold the i_mutex to suspend application writes temporarily; + * this prevents long-running writing applications from blocking + * nfs_wb_nocommit. + */ + if (S_ISREG(inode->i_mode)) { + mutex_lock(&inode->i_mutex); nfs_wb_nocommit(inode); + mutex_unlock(&inode->i_mutex); + } /* * We may force a getattr if the user cares about atime. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs