ocfs2: POSIX file locks support

This is actually pretty easy since fs/dlm already handles the bulk of the
work. The Ocfs2 userspace cluster stack module already uses fs/dlm as the
underlying lock manager, so I only had to add the right calls.

Cluster-aware POSIX locks ("plocks") can be turned off by the same means at
UNIX locks - mount with 'noflocks', or create a local-only Ocfs2 volume.
Internally, the file system uses two sets of file_operations, depending on
whether cluster aware plocks is required. This turns out to be easier than
implementing local-only versions of ->lock.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/fs/ocfs2/stackglue.h b/fs/ocfs2/stackglue.h
index db56281dd1be..c571af375ef8 100644
--- a/fs/ocfs2/stackglue.h
+++ b/fs/ocfs2/stackglue.h
@@ -28,6 +28,10 @@
 #include "dlm/dlmapi.h"
 #include <linux/dlm.h>
 
+/* Needed for plock-related prototypes */
+struct file;
+struct file_lock;
+
 /*
  * dlmconstants.h does not have a LOCAL flag.  We hope to remove it
  * some day, but right now we need it.  Let's fake it.  This value is larger
@@ -187,6 +191,17 @@ struct ocfs2_stack_operations {
         void *(*lock_lvb)(union ocfs2_dlm_lksb *lksb);
 
         /*
+         * Cluster-aware posix locks
+         *
+         * This is NULL for stacks which do not support posix locks.
+         */
+        int (*plock)(struct ocfs2_cluster_connection *conn,
+                     u64 ino,
+                     struct file *file,
+                     int cmd,
+                     struct file_lock *fl);
+
+        /*
          * This is an optoinal debugging hook.  If provided, the
          * stack can dump debugging information about this lock.
          */
@@ -240,6 +255,10 @@ int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb);
 void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb);
 void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb);
 
+int ocfs2_stack_supports_plocks(void);
+int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
+                struct file *file, int cmd, struct file_lock *fl);
+
 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto);