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 <[EMAIL PROTECTED]>
Cc: Sunil Mushran <[EMAIL PROTECTED]>
Cc: Mark Fasheh <[EMAIL PROTECTED]>
Cc: Jeff Mahoney <[EMAIL PROTECTED]>
---
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
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