[DLM] canceling deadlocked lock

Add a function that can be used through libdlm by a system daemon to cancel
another process's deadlocked lock.  A completion ast with EDEADLK is returned
to the process waiting for the lock.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index 329da1b5285f..6438941ab1f8 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -156,6 +156,7 @@ static int lkb_is_endoflife(struct dlm_lkb *lkb, int sb_status, int type)
 		return 1;
 	case -DLM_ECANCEL:
 	case -ETIMEDOUT:
+	case -EDEADLK:
 		if (lkb->lkb_grmode == DLM_LOCK_IV)
 			return 1;
 		break;
@@ -320,6 +321,22 @@ static int device_user_unlock(struct dlm_user_proc *proc,
 	return error;
 }
 
+static int device_user_deadlock(struct dlm_user_proc *proc,
+				struct dlm_lock_params *params)
+{
+	struct dlm_ls *ls;
+	int error;
+
+	ls = dlm_find_lockspace_local(proc->lockspace);
+	if (!ls)
+		return -ENOENT;
+
+	error = dlm_user_deadlock(ls, params->flags, params->lkid);
+
+	dlm_put_lockspace(ls);
+	return error;
+}
+
 static int create_misc_device(struct dlm_ls *ls, char *name)
 {
 	int error, len;
@@ -545,6 +562,14 @@ static ssize_t device_write(struct file *file, const char __user *buf,
 		error = device_user_unlock(proc, &kbuf->i.lock);
 		break;
 
+	case DLM_USER_DEADLOCK:
+		if (!proc) {
+			log_print("no locking on control device");
+			goto out_sig;
+		}
+		error = device_user_deadlock(proc, &kbuf->i.lock);
+		break;
+
 	case DLM_USER_CREATE_LOCKSPACE:
 		if (proc) {
 			log_print("create/remove only on control device");