dlm: cleanup plock_op vs plock_xop

[ Upstream commit bcbb4ba6c9ba81e6975b642a2cade68044cd8a66 ]

Lately the different casting between plock_op and plock_xop and list
holders which was involved showed some issues which were hard to see.
This patch removes the "plock_xop" structure and introduces a
"struct plock_async_data". This structure will be set in "struct plock_op"
in case of asynchronous lock handling as the original "plock_xop" was
made for. There is no need anymore to cast pointers around for
additional fields in case of asynchronous lock handling.  As disadvantage
another allocation was introduces but only needed in the asynchronous
case which is currently only used in combination with nfs lockd.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Stable-dep-of: 59e45c758ca1 ("fs: dlm: interrupt posix locks only when process is killed")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
diff --git a/fs/dlm/plock.c b/fs/dlm/plock.c
index 25bf72c..943f4b4 100644
--- a/fs/dlm/plock.c
+++ b/fs/dlm/plock.c
@@ -22,21 +22,21 @@
 static wait_queue_head_t send_wq;
 static wait_queue_head_t recv_wq;
 
+struct plock_async_data {
+	void *fl;
+	void *file;
+	struct file_lock flc;
+	int (*callback)(struct file_lock *fl, int result);
+};
+
 struct plock_op {
 	struct list_head list;
 	int done;
 	struct dlm_plock_info info;
-	int (*callback)(struct file_lock *fl, int result);
+	/* if set indicates async handling */
+	struct plock_async_data *data;
 };
 
-struct plock_xop {
-	struct plock_op xop;
-	void *fl;
-	void *file;
-	struct file_lock flc;
-};
-
-
 static inline void set_version(struct dlm_plock_info *info)
 {
 	info->version[0] = DLM_PLOCK_VERSION_MAJOR;
@@ -61,6 +61,12 @@
 	return 0;
 }
 
+static void dlm_release_plock_op(struct plock_op *op)
+{
+	kfree(op->data);
+	kfree(op);
+}
+
 static void send_op(struct plock_op *op)
 {
 	set_version(&op->info);
@@ -104,22 +110,21 @@
 int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
 		   int cmd, struct file_lock *fl)
 {
+	struct plock_async_data *op_data;
 	struct dlm_ls *ls;
 	struct plock_op *op;
-	struct plock_xop *xop;
 	int rv;
 
 	ls = dlm_find_lockspace_local(lockspace);
 	if (!ls)
 		return -EINVAL;
 
-	xop = kzalloc(sizeof(*xop), GFP_NOFS);
-	if (!xop) {
+	op = kzalloc(sizeof(*op), GFP_NOFS);
+	if (!op) {
 		rv = -ENOMEM;
 		goto out;
 	}
 
-	op = &xop->xop;
 	op->info.optype		= DLM_PLOCK_OP_LOCK;
 	op->info.pid		= fl->fl_pid;
 	op->info.ex		= (fl->fl_type == F_WRLCK);
@@ -128,22 +133,32 @@
 	op->info.number		= number;
 	op->info.start		= fl->fl_start;
 	op->info.end		= fl->fl_end;
+	/* async handling */
 	if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
+		op_data = kzalloc(sizeof(*op_data), GFP_NOFS);
+		if (!op_data) {
+			dlm_release_plock_op(op);
+			rv = -ENOMEM;
+			goto out;
+		}
+
 		/* fl_owner is lockd which doesn't distinguish
 		   processes on the nfs client */
 		op->info.owner	= (__u64) fl->fl_pid;
-		op->callback	= fl->fl_lmops->lm_grant;
-		locks_init_lock(&xop->flc);
-		locks_copy_lock(&xop->flc, fl);
-		xop->fl		= fl;
-		xop->file	= file;
+		op_data->callback = fl->fl_lmops->lm_grant;
+		locks_init_lock(&op_data->flc);
+		locks_copy_lock(&op_data->flc, fl);
+		op_data->fl		= fl;
+		op_data->file	= file;
+
+		op->data = op_data;
 	} else {
 		op->info.owner	= (__u64)(long) fl->fl_owner;
 	}
 
 	send_op(op);
 
-	if (!op->callback) {
+	if (!op->data) {
 		rv = wait_event_interruptible(recv_wq, (op->done != 0));
 		if (rv == -ERESTARTSYS) {
 			log_debug(ls, "dlm_posix_lock: wait killed %llx",
@@ -151,7 +166,7 @@
 			spin_lock(&ops_lock);
 			list_del(&op->list);
 			spin_unlock(&ops_lock);
-			kfree(xop);
+			dlm_release_plock_op(op);
 			do_unlock_close(ls, number, file, fl);
 			goto out;
 		}
@@ -176,7 +191,7 @@
 				  (unsigned long long)number);
 	}
 
-	kfree(xop);
+	dlm_release_plock_op(op);
 out:
 	dlm_put_lockspace(ls);
 	return rv;
@@ -186,11 +201,11 @@
 /* Returns failure iff a successful lock operation should be canceled */
 static int dlm_plock_callback(struct plock_op *op)
 {
+	struct plock_async_data *op_data = op->data;
 	struct file *file;
 	struct file_lock *fl;
 	struct file_lock *flc;
 	int (*notify)(struct file_lock *fl, int result) = NULL;
-	struct plock_xop *xop = (struct plock_xop *)op;
 	int rv = 0;
 
 	spin_lock(&ops_lock);
@@ -202,10 +217,10 @@
 	spin_unlock(&ops_lock);
 
 	/* check if the following 2 are still valid or make a copy */
-	file = xop->file;
-	flc = &xop->flc;
-	fl = xop->fl;
-	notify = op->callback;
+	file = op_data->file;
+	flc = &op_data->flc;
+	fl = op_data->fl;
+	notify = op_data->callback;
 
 	if (op->info.rv) {
 		notify(fl, op->info.rv);
@@ -236,7 +251,7 @@
 	}
 
 out:
-	kfree(xop);
+	dlm_release_plock_op(op);
 	return rv;
 }
 
@@ -306,7 +321,7 @@
 		rv = 0;
 
 out_free:
-	kfree(op);
+	dlm_release_plock_op(op);
 out:
 	dlm_put_lockspace(ls);
 	fl->fl_flags = fl_flags;
@@ -374,7 +389,7 @@
 		rv = 0;
 	}
 
-	kfree(op);
+	dlm_release_plock_op(op);
 out:
 	dlm_put_lockspace(ls);
 	return rv;
@@ -410,7 +425,7 @@
 	   (the process did not make an unlock call). */
 
 	if (op->info.flags & DLM_PLOCK_FL_CLOSE)
-		kfree(op);
+		dlm_release_plock_op(op);
 
 	if (copy_to_user(u, &info, sizeof(info)))
 		return -EFAULT;
@@ -442,7 +457,7 @@
 		    op->info.owner == info.owner) {
 			list_del_init(&op->list);
 			memcpy(&op->info, &info, sizeof(info));
-			if (op->callback)
+			if (op->data)
 				do_callback = 1;
 			else
 				op->done = 1;