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>
diff --git a/fs/ocfs2/stack_user.c b/fs/ocfs2/stack_user.c
index 353fc35..faec2d8 100644
--- a/fs/ocfs2/stack_user.c
+++ b/fs/ocfs2/stack_user.c
@@ -28,6 +28,7 @@
#include "ocfs2.h" /* For struct ocfs2_lock_res */
#include "stackglue.h"
+#include <linux/dlm_plock.h>
/*
* The control protocol starts with a handshake. Until the handshake
@@ -746,6 +747,37 @@
{
}
+static int user_plock(struct ocfs2_cluster_connection *conn,
+ u64 ino,
+ struct file *file,
+ int cmd,
+ struct file_lock *fl)
+{
+ /*
+ * This more or less just demuxes the plock request into any
+ * one of three dlm calls.
+ *
+ * Internally, fs/dlm will pass these to a misc device, which
+ * a userspace daemon will read and write to.
+ *
+ * For now, cancel requests (which happen internally only),
+ * are turned into unlocks. Most of this function taken from
+ * gfs2_lock.
+ */
+
+ if (cmd == F_CANCELLK) {
+ cmd = F_SETLK;
+ fl->fl_type = F_UNLCK;
+ }
+
+ if (IS_GETLK(cmd))
+ return dlm_posix_get(conn->cc_lockspace, ino, file, fl);
+ else if (fl->fl_type == F_UNLCK)
+ return dlm_posix_unlock(conn->cc_lockspace, ino, file, fl);
+ else
+ return dlm_posix_lock(conn->cc_lockspace, ino, file, cmd, fl);
+}
+
/*
* Compare a requested locking protocol version against the current one.
*
@@ -839,6 +871,7 @@
.dlm_unlock = user_dlm_unlock,
.lock_status = user_dlm_lock_status,
.lock_lvb = user_dlm_lvb,
+ .plock = user_plock,
.dump_lksb = user_dlm_dump_lksb,
};