fs: dlm: add lkb debugfs functionality

This patch adds functionality to add an lkb during runtime. This is a
highly debugging feature only, wrong input can crash the kernel. It is a
early state feature as well. The goal is to provide a user interface for
manipulate dlm state and combine it with the rawmsg feature. It is
debugfs functionality, we don't care about UAPI breakage. Even it's
possible to add lkb's/rsb's which could never be exists in such wat by
using normal DLM operation. The user of this interface always need to
think before using this feature, not every crash which happens can really
occur during normal dlm operation.

Future there should be more functionality to add a more realistic lkb
which reflects normal DLM state inside the kernel. For now this is
enough.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 8b30c9d9e545d..aeb793693d8c5 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -6317,3 +6317,49 @@ int dlm_user_purge(struct dlm_ls *ls, struct dlm_user_proc *proc,
 	return error;
 }
 
+/* debug functionality */
+int dlm_debug_add_lkb(struct dlm_ls *ls, uint32_t lkb_id, char *name, int len,
+		      int lkb_nodeid, unsigned int lkb_flags, int lkb_status)
+{
+	struct dlm_lksb *lksb;
+	struct dlm_lkb *lkb;
+	struct dlm_rsb *r;
+	int error;
+
+	/* we currently can't set a valid user lock */
+	if (lkb_flags & DLM_IFL_USER)
+		return -EOPNOTSUPP;
+
+	lksb = kzalloc(sizeof(*lksb), GFP_NOFS);
+	if (!lksb)
+		return -ENOMEM;
+
+	error = _create_lkb(ls, &lkb, lkb_id, lkb_id + 1);
+	if (error) {
+		kfree(lksb);
+		return error;
+	}
+
+	lkb->lkb_flags = lkb_flags;
+	lkb->lkb_nodeid = lkb_nodeid;
+	lkb->lkb_lksb = lksb;
+	/* user specific pointer, just don't have it NULL for kernel locks */
+	if (~lkb_flags & DLM_IFL_USER)
+		lkb->lkb_astparam = (void *)0xDEADBEEF;
+
+	error = find_rsb(ls, name, len, 0, R_REQUEST, &r);
+	if (error) {
+		kfree(lksb);
+		__put_lkb(ls, lkb);
+		return error;
+	}
+
+	lock_rsb(r);
+	attach_lkb(r, lkb);
+	add_lkb(r, lkb, lkb_status);
+	unlock_rsb(r);
+	put_rsb(r);
+
+	return 0;
+}
+