From: zam <zam>
Date: Thu, 22 Oct 2009 07:35:58 +0000 (+0000)
Subject: Branch HEAD
X-Git-Tag: v1_9_290~5
X-Git-Url: https://git.whamcloud.com/gitweb?a=commitdiff_plain;h=28a4dc177465b6ba6ac16def212578ad14b742e6;p=fs%2Flustre-release.git

Branch HEAD
b=20831
i=nathan.rutman
i=robert.read

Fix a race between do_requeue and client_disconnect_export by protecting
the check for cl_conn_count by the client semaphore.
---

diff --git a/lustre/mgc/mgc_request.c b/lustre/mgc/mgc_request.c
index 337418b..8652566 100644
--- a/lustre/mgc/mgc_request.c
+++ b/lustre/mgc/mgc_request.c
@@ -374,6 +374,10 @@ static void do_requeue(struct config_llog_data *cld)
 {
         LASSERT(atomic_read(&cld->cld_refcount) > 0);
 
+        /* Do not run mgc_process_log on a disconnected export or an
+           export which is being disconnected. Take the client
+           semaphore to make the check non-racy. */
+        down_read(&cld->cld_mgcexp->exp_obd->u.cli.cl_sem);
         if (cld->cld_mgcexp->exp_obd->u.cli.cl_conn_count != 0) {
                 CDEBUG(D_MGC, "updating log %s\n", cld->cld_logname);
                 mgc_process_log(cld->cld_mgcexp->exp_obd, cld);
@@ -381,6 +385,7 @@ static void do_requeue(struct config_llog_data *cld)
                 CDEBUG(D_MGC, "disconnecting, won't update log %s\n",
                        cld->cld_logname);
         }
+        up_read(&cld->cld_mgcexp->exp_obd->u.cli.cl_sem);
 
         /* Whether we enqueued again or not in mgc_process_log, we're done
          * with the ref from the old enqueue */