afs: Avoid memory leak on recursive write flock

When a process requests an exclusive lock on a file on which it
already holds an exclusive lock, we basically form a no-op. However,
HandleFlock was allocating a new SimpleLocks and attaching it to
avc->slocks, without freeing the old SimpleLocks structure.

Since we don't need to do anything if we already hold an exclusive
lock, just break out of the loop right away when we detect that
scenario. Thus we avoid adding a new structure to avc->slocks, and we
avoid a memory leak.

Reviewed-on: http://gerrit.openafs.org/4395
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit ba9ae1ed7c269d7c080b5ce99b3b4bb2fe0a2a6f)

Change-Id: I9e45a51e02774c555c6d5cb5ba9d0407b8442215
Reviewed-on: http://gerrit.openafs.org/5765
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>

diff --git a/src/afs/VNOPS/afs_vnop_flock.c b/src/afs/VNOPS/afs_vnop_flock.c
index f904d50c4f4021fe69d298c0dc8f47bcc9efa376..2eeb427c3f4fb1b09aab44240cd1ebf84ff81a8a 100644 (file)
--- a/src/afs/VNOPS/afs_vnop_flock.c
+++ b/src/afs/VNOPS/afs_vnop_flock.c
@@ -408,8 +408,14 @@ HandleFlock(struct vcache *avc, int acom, struct vrequest *areq,
            } else if (avc->flockCount == -1 && (acom & LOCK_EX)) {
                if (lockIdcmp2(&flock, avc, NULL, 1, clid)) {
                    code = EWOULDBLOCK;
-               } else
+               } else {
                    code = 0;
+                   /* We've just re-grabbed an exclusive lock, so we don't
+                    * need to contact the fileserver, and we don't need to
+                    * add the lock to avc->slocks (since we already have a
+                    * lock there). So, we are done. */
+                   break;
+               }
            }
            if (code == 0) {
                /* compatible here, decide if needs to go to file server.  If