From: Michal Privoznik <mprivozn@redhat.com>
Date: Fri, 7 Sep 2018 14:07:13 +0000 (+0200)
Subject: lock_driver: Introduce VIR_LOCK_MANAGER_ACQUIRE_ROLLBACK
X-Git-Tag: v4.8.0-rc1~157
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=385eb8399bdb1610447c2857abfe99cee4a9fb9e;p=thirdparty%2Flibvirt.git

lock_driver: Introduce VIR_LOCK_MANAGER_ACQUIRE_ROLLBACK

Soon there will be a virtlockd client that wants to either lock
all the resources or none (in order to avoid virtlockd killing
the client on connection close). Because on the RPC layer we can
only acquire one resource at a time, we have to perform a
rollback once we hit a resource that can't be acquired.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
---

diff --git a/src/locking/lock_driver.h b/src/locking/lock_driver.h
index 9be0abcfba..7c8f744be3 100644
--- a/src/locking/lock_driver.h
+++ b/src/locking/lock_driver.h
@@ -67,6 +67,10 @@ typedef enum {
     VIR_LOCK_MANAGER_ACQUIRE_REGISTER_ONLY = (1 << 0),
     /* Prevent further lock/unlock calls from this process */
     VIR_LOCK_MANAGER_ACQUIRE_RESTRICT = (1 << 1),
+    /* Used when acquiring more resources in which one of them
+     * can't be acquired, perform a rollback and release all
+     * resources acquired so far. */
+    VIR_LOCK_MANAGER_ACQUIRE_ROLLBACK = (1 << 2),
 } virLockManagerAcquireFlags;
 
 typedef enum {
diff --git a/src/locking/lock_driver_lockd.c b/src/locking/lock_driver_lockd.c
index d6551e125c..85cdcf97be 100644
--- a/src/locking/lock_driver_lockd.c
+++ b/src/locking/lock_driver_lockd.c
@@ -735,6 +735,34 @@ static int virLockManagerLockDaemonAddResource(virLockManagerPtr lock,
 }
 
 
+static int virLockManagerLockDaemonReleaseImpl(virNetClientPtr client,
+                                               virNetClientProgramPtr program,
+                                               int counter,
+                                               virLockManagerLockDaemonResourcePtr res)
+{
+    virLockSpaceProtocolReleaseResourceArgs args;
+
+    memset(&args, 0, sizeof(args));
+
+    args.path = res->lockspace;
+    args.name = res->name;
+    args.flags = res->flags;
+
+    args.flags &=
+        ~(VIR_LOCK_SPACE_PROTOCOL_ACQUIRE_RESOURCE_SHARED |
+          VIR_LOCK_SPACE_PROTOCOL_ACQUIRE_RESOURCE_AUTOCREATE |
+          VIR_LOCK_SPACE_PROTOCOL_ACQUIRE_RESOURCE_METADATA);
+
+    return virNetClientProgramCall(program,
+                                   client,
+                                   counter,
+                                   VIR_LOCK_SPACE_PROTOCOL_PROC_RELEASE_RESOURCE,
+                                   0, NULL, NULL, NULL,
+                                   (xdrproc_t)xdr_virLockSpaceProtocolReleaseResourceArgs, &args,
+                                   (xdrproc_t)xdr_void, NULL);
+}
+
+
 static int virLockManagerLockDaemonAcquire(virLockManagerPtr lock,
                                            const char *state ATTRIBUTE_UNUSED,
                                            unsigned int flags,
@@ -745,10 +773,13 @@ static int virLockManagerLockDaemonAcquire(virLockManagerPtr lock,
     virNetClientProgramPtr program = NULL;
     int counter = 0;
     int rv = -1;
+    ssize_t i;
+    ssize_t lastGood = -1;
     virLockManagerLockDaemonPrivatePtr priv = lock->privateData;
 
     virCheckFlags(VIR_LOCK_MANAGER_ACQUIRE_REGISTER_ONLY |
-                  VIR_LOCK_MANAGER_ACQUIRE_RESTRICT, -1);
+                  VIR_LOCK_MANAGER_ACQUIRE_RESTRICT |
+                  VIR_LOCK_MANAGER_ACQUIRE_ROLLBACK, -1);
 
     if (priv->type == VIR_LOCK_MANAGER_OBJECT_TYPE_DOMAIN &&
         priv->nresources == 0 &&
@@ -767,7 +798,6 @@ static int virLockManagerLockDaemonAcquire(virLockManagerPtr lock,
         goto cleanup;
 
     if (!(flags & VIR_LOCK_MANAGER_ACQUIRE_REGISTER_ONLY)) {
-        size_t i;
         for (i = 0; i < priv->nresources; i++) {
             virLockSpaceProtocolAcquireResourceArgs args;
 
@@ -785,6 +815,7 @@ static int virLockManagerLockDaemonAcquire(virLockManagerPtr lock,
                                         (xdrproc_t)xdr_virLockSpaceProtocolAcquireResourceArgs, &args,
                                         (xdrproc_t)xdr_void, NULL) < 0)
                 goto cleanup;
+            lastGood = i;
         }
     }
 
@@ -795,8 +826,28 @@ static int virLockManagerLockDaemonAcquire(virLockManagerPtr lock,
     rv = 0;
 
  cleanup:
-    if (rv != 0 && fd)
-        VIR_FORCE_CLOSE(*fd);
+    if (rv < 0) {
+        int saved_errno = errno;
+        virErrorPtr origerr;
+
+        virErrorPreserveLast(&origerr);
+        if (fd)
+            VIR_FORCE_CLOSE(*fd);
+
+        if (flags & VIR_LOCK_MANAGER_ACQUIRE_ROLLBACK) {
+            for (i = lastGood; i >= 0; i--) {
+                virLockManagerLockDaemonResourcePtr res = &priv->resources[i];
+
+                if (virLockManagerLockDaemonReleaseImpl(client, program,
+                                                        counter++, res) < 0)
+                    VIR_WARN("Unable to release resource lockspace=%s name=%s",
+                             res->lockspace, res->name);
+            }
+        }
+
+        virErrorRestore(&origerr);
+        errno = saved_errno;
+    }
     virNetClientClose(client);
     virObjectUnref(client);
     virObjectUnref(program);
@@ -824,27 +875,10 @@ static int virLockManagerLockDaemonRelease(virLockManagerPtr lock,
         goto cleanup;
 
     for (i = 0; i < priv->nresources; i++) {
-        virLockSpaceProtocolReleaseResourceArgs args;
-
-        memset(&args, 0, sizeof(args));
+        virLockManagerLockDaemonResourcePtr res = &priv->resources[i];
 
-        if (priv->resources[i].lockspace)
-            args.path = priv->resources[i].lockspace;
-        args.name = priv->resources[i].name;
-        args.flags = priv->resources[i].flags;
-
-        args.flags &=
-            ~(VIR_LOCK_SPACE_PROTOCOL_ACQUIRE_RESOURCE_SHARED |
-              VIR_LOCK_SPACE_PROTOCOL_ACQUIRE_RESOURCE_AUTOCREATE |
-              VIR_LOCK_SPACE_PROTOCOL_ACQUIRE_RESOURCE_METADATA);
-
-        if (virNetClientProgramCall(program,
-                                    client,
-                                    counter++,
-                                    VIR_LOCK_SPACE_PROTOCOL_PROC_RELEASE_RESOURCE,
-                                    0, NULL, NULL, NULL,
-                                    (xdrproc_t)xdr_virLockSpaceProtocolReleaseResourceArgs, &args,
-                                    (xdrproc_t)xdr_void, NULL) < 0)
+        if (virLockManagerLockDaemonReleaseImpl(client, program,
+                                                counter++, res) < 0)
             goto cleanup;
     }