From 63eab2b00bcff620682e8570367458c9619a9970 Mon Sep 17 00:00:00 2001
From: Alexander Aring <aahringo@redhat.com>
Date: Tue, 2 Nov 2021 15:17:23 -0400
Subject: fs: dlm: add lkb waiters debugfs functionality

This patch adds functionality to put a lkb to the waiters state. It can
be useful to combine this feature with the "rawmsg" debugfs
functionality. It will bring the DLM lkb into a state that a message
will be parsed by the kernel.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
---
 fs/dlm/debug_fs.c | 27 ++++++++++++++++++++++++++-
 fs/dlm/lock.c     | 15 +++++++++++++++
 fs/dlm/lock.h     |  2 ++
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c
index 2ead4751d655..df6f3f107be4 100644
--- a/fs/dlm/debug_fs.c
+++ b/fs/dlm/debug_fs.c
@@ -754,10 +754,35 @@ static ssize_t waiters_read(struct file *file, char __user *userbuf,
 	return rv;
 }
 
+static ssize_t waiters_write(struct file *file, const char __user *user_buf,
+			     size_t count, loff_t *ppos)
+{
+	struct dlm_ls *ls = file->private_data;
+	int mstype, to_nodeid;
+	char buf[128] = {};
+	uint32_t lkb_id;
+	int n, error;
+
+	if (copy_from_user(buf, user_buf,
+			   min_t(size_t, sizeof(buf) - 1, count)))
+		return -EFAULT;
+
+	n = sscanf(buf, "%x %d %d", &lkb_id, &mstype, &to_nodeid);
+	if (n != 3)
+		return -EINVAL;
+
+	error = dlm_debug_add_lkb_to_waiters(ls, lkb_id, mstype, to_nodeid);
+	if (error)
+		return error;
+
+	return count;
+}
+
 static const struct file_operations waiters_fops = {
 	.owner   = THIS_MODULE,
 	.open    = simple_open,
 	.read    = waiters_read,
+	.write   = waiters_write,
 	.llseek  = default_llseek,
 };
 
@@ -907,7 +932,7 @@ void dlm_create_debug_file(struct dlm_ls *ls)
 	snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_waiters", ls->ls_name);
 
 	ls->ls_debug_waiters_dentry = debugfs_create_file(name,
-							  S_IFREG | S_IRUGO,
+							  0644,
 							  dlm_root,
 							  ls,
 							  &waiters_fops);
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index aeb793693d8c..0dbe273566c0 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -6363,3 +6363,18 @@ int dlm_debug_add_lkb(struct dlm_ls *ls, uint32_t lkb_id, char *name, int len,
 	return 0;
 }
 
+int dlm_debug_add_lkb_to_waiters(struct dlm_ls *ls, uint32_t lkb_id,
+				 int mstype, int to_nodeid)
+{
+	struct dlm_lkb *lkb;
+	int error;
+
+	error = find_lkb(ls, lkb_id, &lkb);
+	if (error)
+		return error;
+
+	error = add_to_waiters(lkb, mstype, to_nodeid);
+	dlm_put_lkb(lkb);
+	return error;
+}
+
diff --git a/fs/dlm/lock.h b/fs/dlm/lock.h
index 863a66e128a2..252a5898f908 100644
--- a/fs/dlm/lock.h
+++ b/fs/dlm/lock.h
@@ -60,6 +60,8 @@ int dlm_user_deadlock(struct dlm_ls *ls, uint32_t flags, uint32_t lkid);
 void dlm_clear_proc_locks(struct dlm_ls *ls, struct dlm_user_proc *proc);
 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);
+int dlm_debug_add_lkb_to_waiters(struct dlm_ls *ls, uint32_t lkb_id,
+				 int mstype, int to_nodeid);
 
 static inline int is_master(struct dlm_rsb *r)
 {
-- 
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