From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id 9CC747F3F for ; Fri, 17 Apr 2015 02:40:39 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay3.corp.sgi.com (Postfix) with ESMTP id 36598AC003 for ; Fri, 17 Apr 2015 00:40:39 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id LITQERBFNq7t0EHV (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Fri, 17 Apr 2015 00:40:35 -0700 (PDT) From: xuw2015@gmail.com Subject: [PATCH v2] xfs: use percpu_counter_read_positive for mp->m_icount Date: Fri, 17 Apr 2015 15:40:23 +0800 Message-Id: <1429256423-9809-1-git-send-email-xuw2015@gmail.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com Cc: George Wang From: George Wang Function percpu_counter_read just return the current counter, which can be negative. This will cause the checking of "allocated inode counts <= m_maxicount" false positive. Use percpu_counter_read_positive can solve this problem, and be consistent with the purpose to introduce percpu mechanism to xfs. Signed-off-by: George Wang --- fs/xfs/libxfs/xfs_ialloc.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c index 07349a1..1c9e755 100644 --- a/fs/xfs/libxfs/xfs_ialloc.c +++ b/fs/xfs/libxfs/xfs_ialloc.c @@ -376,7 +376,7 @@ xfs_ialloc_ag_alloc( */ newlen = args.mp->m_ialloc_inos; if (args.mp->m_maxicount && - percpu_counter_read(&args.mp->m_icount) + newlen > + percpu_counter_read_positive(&args.mp->m_icount) + newlen > args.mp->m_maxicount) return -ENOSPC; args.minlen = args.maxlen = args.mp->m_ialloc_blks; @@ -1339,10 +1339,13 @@ xfs_dialloc( * If we have already hit the ceiling of inode blocks then clear * okalloc so we scan all available agi structures for a free * inode. + * + * Read rough value of mp->m_icount by percpu_counter_read_positive, + * which will sacrifice the preciseness but improve the performance. */ if (mp->m_maxicount && - percpu_counter_read(&mp->m_icount) + mp->m_ialloc_inos > - mp->m_maxicount) { + percpu_counter_read_positive(&mp->m_icount) + mp->m_ialloc_inos + > mp->m_maxicount) { noroom = 1; okalloc = 0; } -- 1.9.3 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs