From mboxrd@z Thu Jan 1 00:00:00 1970 From: Coly Li Date: Thu, 04 Dec 2008 18:38:37 +0800 Subject: [Ocfs2-devel] [PATCH] ocfs2/dlm: fix lockres mastery race, v2 Message-ID: <4937B32D.2040600@suse.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com dlm_get_lock_resource() is supposed to return a lock resource with a proper master. If multiple concurrent threads attempt to lookup the lockres for the same lockid, one or more threads are likely to return a lockres without a proper master, if the lock mastery is underway. This patch makes the threads wait in dlm_get_lock_resource() while the mastery is underway, ensuring all threads return the lockres with a proper master. This issue is known limited to users using the flock() syscall. For all other fs operations, dlmglue should ensure that only one thread is performing dlm operations for a given lockid at any one time. Thank Sunil for his review and comments. Signed-off-by: Coly Li Cc: Sunil Mushran Cc: Mark Fasheh Cc: Jeff Mahoney --- fs/ocfs2/dlm/dlmmaster.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c index 44f87ca..dd1e754 100644 --- a/fs/ocfs2/dlm/dlmmaster.c +++ b/fs/ocfs2/dlm/dlmmaster.c @@ -742,6 +742,17 @@ lookup: goto lookup; } + /* wait for lock resource is being mastered by another thread */ + spin_lock(&tmpres->spinlock); + if (tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN) { + __dlm_wait_on_lockres_flags(tmpres, DLM_LOCK_RES_IN_PROGRESS); + spin_unlock(&tmpres->spinlock); + dlm_lockres_put(tmpres); + tmpres = NULL; + goto lookup; + } + spin_unlock(&tmpres->spinlock); + mlog(0, "found in hash!\n"); if (res) dlm_lockres_put(res); -- Coly Li SuSE PRC Labs