Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757981Ab0FFOxt (ORCPT ); Sun, 6 Jun 2010 10:53:49 -0400 Received: from smtp.nokia.com ([192.100.105.134]:18235 "EHLO mgw-mx09.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934025Ab0FFOxi (ORCPT ); Sun, 6 Jun 2010 10:53:38 -0400 From: Artem Bityutskiy To: Al Viro Cc: Andrew Morton , LKML , linux-fsdevel@vger.kernel.org, Artem Bityutskiy , Boaz Harrosh Subject: [PATCHv5 10/16] exofs: fix race condition in marking SB dirty Date: Sun, 6 Jun 2010 17:50:23 +0300 Message-Id: <1275835829-1478-11-git-send-email-dedekind1@gmail.com> X-Mailer: git-send-email 1.7.0.1 In-Reply-To: <1275835829-1478-1-git-send-email-dedekind1@gmail.com> References: <1275835829-1478-1-git-send-email-dedekind1@gmail.com> X-OriginalArrivalTime: 06 Jun 2010 14:53:29.0637 (UTC) FILETIME=[06B46D50:01CB0588] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1814 Lines: 48 From: Artem Bityutskiy When synchronizing the superblock, exofs first initiates the SB write (a) and then marks the superblock as clean (b). However, meanwhile (between (a) and (b)) someone else can modify the superblock and mark it as dirty. This would be a race condition, and the result would be that we'd end up with a modified superblock which would nevertheless be marked as clean (because of (b)). This means that 'sync_supers()' would never call our '->write_super()', at least not until yet another SB change happens. This patch fixes this race condition by marking the superblock as clean before initiating the write operation. Signed-off-by: Artem Bityutskiy Cc: Boaz Harrosh --- fs/exofs/super.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/fs/exofs/super.c b/fs/exofs/super.c index 74ccbdc..0b432b9 100644 --- a/fs/exofs/super.c +++ b/fs/exofs/super.c @@ -219,6 +219,7 @@ int exofs_sync_fs(struct super_block *sb, int wait) * the fscb->s_dev_table_oid member. There is no read-modify-write * here. */ + sb_mark_clean(sb); ios->length = offsetof(struct exofs_fscb, s_dev_table_oid); memset(fscb, 0, ios->length); fscb->s_nextid = cpu_to_le64(sbi->s_nextid); @@ -237,7 +238,6 @@ int exofs_sync_fs(struct super_block *sb, int wait) EXOFS_ERR("%s: exofs_sbi_write failed.\n", __func__); goto out; } - sb_mark_clean(sb); out: EXOFS_DBGMSG("s_nextid=0x%llx ret=%d\n", _LLU(sbi->s_nextid), ret); -- 1.7.0.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/