Linux: drop GLOCK before calling dput

Holding the GLOCK when calling dput can result in a deadlock when
the kernel calls back into afs_dentry_iput.  It should be safe
to drop the lock here.

Change-Id: I8966aea7336b39b4c3ec265a53d820fc6135eeaf
Reviewed-on: http://gerrit.openafs.org/8046
Reviewed-by: Simon Wilkinson <simonxwilkinson@gmail.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: Derrick Brashear <shadow@your-file-system.com>

diff --git a/src/afs/afs_pioctl.c b/src/afs/afs_pioctl.c
index aab52ff..0836b87 100644 (file)
--- a/src/afs/afs_pioctl.c
+++ b/src/afs/afs_pioctl.c
@@ -1239,7 +1239,13 @@ afs_syscall_pioctl(char *path, unsigned int com, caddr_t cmarg, int follow)
 #endif /* AFS_NEED_CLIENTCONTEXT */
     if (vp) {
 #ifdef AFS_LINUX22_ENV
+       /*
+        * Holding the global lock when calling dput can cause a deadlock
+        * when the kernel calls back into afs_dentry_iput
+        */
+       AFS_GUNLOCK();
        dput(dp);
+       AFS_GLOCK();
 #else
 #if defined(AFS_FBSD80_ENV)
     if (VOP_ISLOCKED(vp))