fs: dlm: debugfs for queued callbacks

It was useful to debug an issue with the callback queue to check if any
callbacks in any lkb are for some reason not processed by the callback
workqueue. The mentioned issue was fixed by commit a034c13 ("fs:
dlm: fix DLM_IFL_CB_PENDING gets overwritten"). If there are similar
issue that looks like a ast callback was not processed, we can confirm
now that it is not sitting to be processed by the callback workqueue
anymore.

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

Author: Alexander Aring

fs/dlm/debug_fs.c

@@ -18,6 +18,7 @@
 #include "dlm_internal.h"
 #include "midcomms.h"
 #include "lock.h"
+#include "ast.h"
 
 #define DLM_DEBUG_BUF_LEN 4096
 static char debug_buf[DLM_DEBUG_BUF_LEN];
@@ -365,6 +366,52 @@ static void print_format4(struct dlm_rsb *r, struct seq_file *s)
 	unlock_rsb(r);
 }
 
+static void print_format5_lock(struct seq_file *s, struct dlm_lkb *lkb)
+{
+	struct dlm_callback *cb;
+
+	/* lkb_id lkb_flags mode flags sb_status sb_flags */
+
+	spin_lock(&lkb->lkb_cb_lock);
+	list_for_each_entry(cb, &lkb->lkb_callbacks, list) {
+		seq_printf(s, "%x %x %d %x %d %x\n",
+			   lkb->lkb_id,
+			   dlm_iflags_val(lkb),
+			   cb->mode,
+			   cb->flags,
+			   cb->sb_status,
+			   cb->sb_flags);
+	}
+	spin_unlock(&lkb->lkb_cb_lock);
+}
+
+static void print_format5(struct dlm_rsb *r, struct seq_file *s)
+{
+	struct dlm_lkb *lkb;
+
+	lock_rsb(r);
+
+	list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue) {
+		print_format5_lock(s, lkb);
+		if (seq_has_overflowed(s))
+			goto out;
+	}
+
+	list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue) {
+		print_format5_lock(s, lkb);
+		if (seq_has_overflowed(s))
+			goto out;
+	}
+
+	list_for_each_entry(lkb, &r->res_waitqueue, lkb_statequeue) {
+		print_format5_lock(s, lkb);
+		if (seq_has_overflowed(s))
+			goto out;
+	}
+ out:
+	unlock_rsb(r);
+}
+
 struct rsbtbl_iter {
 	struct dlm_rsb *rsb;
 	unsigned bucket;
@@ -408,6 +455,13 @@ static int table_seq_show(struct seq_file *seq, void *iter_ptr)
 		}
 		print_format4(ri->rsb, seq);
 		break;
+	case 5:
+		if (ri->header) {
+			seq_puts(seq, "lkb_id lkb_flags mode flags sb_status sb_flags\n");
+			ri->header = 0;
+		}
+		print_format5(ri->rsb, seq);
+		break;
 	}
 
 	return 0;
@@ -417,6 +471,7 @@ static const struct seq_operations format1_seq_ops;
 static const struct seq_operations format2_seq_ops;
 static const struct seq_operations format3_seq_ops;
 static const struct seq_operations format4_seq_ops;
+static const struct seq_operations format5_seq_ops;
 
 static void *table_seq_start(struct seq_file *seq, loff_t *pos)
 {
@@ -448,6 +503,8 @@ static void *table_seq_start(struct seq_file *seq, loff_t *pos)
 		ri->format = 3;
 	if (seq->op == &format4_seq_ops)
 		ri->format = 4;
+	if (seq->op == &format5_seq_ops)
+		ri->format = 5;
 
 	tree = toss ? &ls->ls_rsbtbl[bucket].toss : &ls->ls_rsbtbl[bucket].keep;
 
@@ -602,10 +659,18 @@ static const struct seq_operations format4_seq_ops = {
 	.show  = table_seq_show,
 };
 
+static const struct seq_operations format5_seq_ops = {
+	.start = table_seq_start,
+	.next  = table_seq_next,
+	.stop  = table_seq_stop,
+	.show  = table_seq_show,
+};
+
 static const struct file_operations format1_fops;
 static const struct file_operations format2_fops;
 static const struct file_operations format3_fops;
 static const struct file_operations format4_fops;
+static const struct file_operations format5_fops;
 
 static int table_open1(struct inode *inode, struct file *file)
 {
@@ -683,7 +748,21 @@ static int table_open4(struct inode *inode, struct file *file)
 	struct seq_file *seq;
 	int ret;
 
-	ret = seq_open(file, &format4_seq_ops);
+	ret = seq_open(file, &format5_seq_ops);
+	if (ret)
+		return ret;
+
+	seq = file->private_data;
+	seq->private = inode->i_private; /* the dlm_ls */
+	return 0;
+}
+
+static int table_open5(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq;
+	int ret;
+
+	ret = seq_open(file, &format5_seq_ops);
 	if (ret)
 		return ret;
 
@@ -725,6 +804,14 @@ static const struct file_operations format4_fops = {
 	.release = seq_release
 };
 
+static const struct file_operations format5_fops = {
+	.owner   = THIS_MODULE,
+	.open    = table_open5,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = seq_release
+};
+
 /*
  * dump lkb's on the ls_waiters list
  */
@@ -793,6 +880,7 @@ void dlm_delete_debug_file(struct dlm_ls *ls)
 	debugfs_remove(ls->ls_debug_locks_dentry);
 	debugfs_remove(ls->ls_debug_all_dentry);
 	debugfs_remove(ls->ls_debug_toss_dentry);
+	debugfs_remove(ls->ls_debug_queued_asts_dentry);
 }
 
 static int dlm_state_show(struct seq_file *file, void *offset)
@@ -936,6 +1024,17 @@ void dlm_create_debug_file(struct dlm_ls *ls)
 							  dlm_root,
 							  ls,
 							  &waiters_fops);
+
+	/* format 5 */
+
+	memset(name, 0, sizeof(name));
+	snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_queued_asts", ls->ls_name);
+
+	ls->ls_debug_queued_asts_dentry = debugfs_create_file(name,
+							      0644,
+							      dlm_root,
+							      ls,
+							      &format5_fops);
 }
 
 void __init dlm_register_debugfs(void)

fs/dlm/dlm_internal.h

@@ -598,6 +598,7 @@ struct dlm_ls {
 	struct dentry		*ls_debug_locks_dentry; /* debugfs */
 	struct dentry		*ls_debug_all_dentry; /* debugfs */
 	struct dentry		*ls_debug_toss_dentry; /* debugfs */
+	struct dentry		*ls_debug_queued_asts_dentry; /* debugfs */
 
 	wait_queue_head_t	ls_uevent_wait;	/* user part of join/leave */
 	int			ls_uevent_result;