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[libvirt] [PATCH] sanlock: Retry after EINPROGRESS



It may take some time for sanlock to add a lockspace. And if user
restart libvirtd service meanwhile, the fresh daemon can fail adding the
same lockspace with EINPROGRESS. Hence, we should retry a few times
before claiming an error. This issue can be easily reproduced:

for i in {1..1000} ; do echo $i; service libvirtd restart; sleep 2; done
20
Stopping libvirtd daemon:                                  [FAILED]
Starting libvirtd daemon:                                  [  OK  ]
21
Stopping libvirtd daemon:                                  [  OK  ]
Starting libvirtd daemon:                                  [  OK  ]
22
Stopping libvirtd daemon:                                  [  OK  ]
Starting libvirtd daemon:                                  [  OK  ]

 error : virLockManagerSanlockSetupLockspace:334 : Unable to add
 lockspace /var/lib/libvirt/sanlock/__LIBVIRT__DISKS__: Operation now in
 progress
---
 src/locking/lock_driver_sanlock.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/src/locking/lock_driver_sanlock.c b/src/locking/lock_driver_sanlock.c
index d24f3d6..6d02ac6 100644
--- a/src/locking/lock_driver_sanlock.c
+++ b/src/locking/lock_driver_sanlock.c
@@ -184,6 +184,11 @@ static int virLockManagerSanlockLoadConfig(const char *configFile)
     return 0;
 }
 
+/* How much ms sleep before retrying to add a lockspace? */
+#define LOCKSPACE_SLEEP 100
+/* How many times try adding a lockspace? */
+#define LOCKSPACE_RETRIES 10
+
 static int virLockManagerSanlockSetupLockspace(void)
 {
     int fd = -1;
@@ -192,6 +197,7 @@ static int virLockManagerSanlockSetupLockspace(void)
     struct sanlk_lockspace ls;
     char *path = NULL;
     char *dir = NULL;
+    int retries = LOCKSPACE_RETRIES;
 
     if (virAsprintf(&path, "%s/%s",
                     driver->autoDiskLeasePath,
@@ -320,9 +326,17 @@ static int virLockManagerSanlockSetupLockspace(void)
     ls.host_id = driver->hostID;
     /* Stage 2: Try to register the lockspace with the daemon.
      * If the lockspace is already registered, we should get EEXIST back
-     * in which case we can just carry on with life
+     * in which case we can just carry on with life, or EINPROGRESS if
+     * previous libvirtd instance started the work but didn't finish.
+     * Unfortunately, sanlock lacks an API to determine state of lockspace,
+     * so we have to do this blindly.
      */
+retry:
     if ((rv = sanlock_add_lockspace(&ls, 0)) < 0) {
+        if (retries-- && -rv == EINPROGRESS) {
+            usleep(LOCKSPACE_SLEEP * 1000);
+            goto retry;
+        }
         if (-rv != EEXIST) {
             if (rv <= -200)
                 virReportError(VIR_ERR_INTERNAL_ERROR,
-- 
1.7.8.6


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