dlm: move plock code from gfs2

Move the code that handles cluster posix locks from gfs2 into the dlm
so that it can be used by both gfs2 and ocfs2.

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

1 files changed, 439 insertions, 0 deletions

diff --git a/fs/dlm/plock.c b/fs/dlm/plock.c
new file mode 100644
index 0000000..d6d6e37
--- /dev/null
+++ b/fs/dlm/plock.c
@@ -0,0 +1,439 @@
+/*
+ * Copyright (C) 2005-2008 Red Hat, Inc.  All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License version 2.
+ */
+
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/poll.h>
+#include <linux/dlm.h>
+#include <linux/dlm_plock.h>
+
+#include "dlm_internal.h"
+#include "lockspace.h"
+
+static spinlock_t ops_lock;
+static struct list_head send_list;
+static struct list_head recv_list;
+static wait_queue_head_t send_wq;
+static wait_queue_head_t recv_wq;
+
+struct plock_op {
+	struct list_head list;
+	int done;
+	struct dlm_plock_info info;
+};
+
+struct plock_xop {
+	struct plock_op xop;
+	void *callback;
+	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;
+	info->version[1] = DLM_PLOCK_VERSION_MINOR;
+	info->version[2] = DLM_PLOCK_VERSION_PATCH;
+}
+
+static int check_version(struct dlm_plock_info *info)
+{
+	if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) ||
+	    (DLM_PLOCK_VERSION_MINOR < info->version[1])) {
+		log_print("plock device version mismatch: "
+			  "kernel (%u.%u.%u), user (%u.%u.%u)",
+			  DLM_PLOCK_VERSION_MAJOR,
+			  DLM_PLOCK_VERSION_MINOR,
+			  DLM_PLOCK_VERSION_PATCH,
+			  info->version[0],
+			  info->version[1],
+			  info->version[2]);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static void send_op(struct plock_op *op)
+{
+	set_version(&op->info);
+	INIT_LIST_HEAD(&op->list);
+	spin_lock(&ops_lock);
+	list_add_tail(&op->list, &send_list);
+	spin_unlock(&ops_lock);
+	wake_up(&send_wq);
+}
+
+int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
+		   int cmd, struct file_lock *fl)
+{
+	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_KERNEL);
+	if (!xop) {
+		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);
+	op->info.wait		= IS_SETLKW(cmd);
+	op->info.fsid		= ls->ls_global_id;
+	op->info.number		= number;
+	op->info.start		= fl->fl_start;
+	op->info.end		= fl->fl_end;
+	if (fl->fl_lmops && fl->fl_lmops->fl_grant) {
+		/* fl_owner is lockd which doesn't distinguish
+		   processes on the nfs client */
+		op->info.owner	= (__u64) fl->fl_pid;
+		xop->callback	= fl->fl_lmops->fl_grant;
+		locks_init_lock(&xop->flc);
+		locks_copy_lock(&xop->flc, fl);
+		xop->fl		= fl;
+		xop->file	= file;
+	} else {
+		op->info.owner	= (__u64)(long) fl->fl_owner;
+		xop->callback	= NULL;
+	}
+
+	send_op(op);
+
+	if (xop->callback == NULL)
+		wait_event(recv_wq, (op->done != 0));
+	else {
+		rv = -EINPROGRESS;
+		goto out;
+	}
+
+	spin_lock(&ops_lock);
+	if (!list_empty(&op->list)) {
+		log_error(ls, "dlm_posix_lock: op on list %llx",
+			  (unsigned long long)number);
+		list_del(&op->list);
+	}
+	spin_unlock(&ops_lock);
+
+	rv = op->info.rv;
+
+	if (!rv) {
+		if (posix_lock_file_wait(file, fl) < 0)
+			log_error(ls, "dlm_posix_lock: vfs lock error %llx",
+				  (unsigned long long)number);
+	}
+
+	kfree(xop);
+out:
+	dlm_put_lockspace(ls);
+	return rv;
+}
+EXPORT_SYMBOL_GPL(dlm_posix_lock);
+
+/* Returns failure iff a succesful lock operation should be canceled */
+static int dlm_plock_callback(struct plock_op *op)
+{
+	struct file *file;
+	struct file_lock *fl;
+	struct file_lock *flc;
+	int (*notify)(void *, void *, int) = NULL;
+	struct plock_xop *xop = (struct plock_xop *)op;
+	int rv = 0;
+
+	spin_lock(&ops_lock);
+	if (!list_empty(&op->list)) {
+		log_print("dlm_plock_callback: op on list %llx",
+			  (unsigned long long)op->info.number);
+		list_del(&op->list);
+	}
+	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 = xop->callback;
+
+	if (op->info.rv) {
+		notify(flc, NULL, op->info.rv);
+		goto out;
+	}
+
+	/* got fs lock; bookkeep locally as well: */
+	flc->fl_flags &= ~FL_SLEEP;
+	if (posix_lock_file(file, flc, NULL)) {
+		/*
+		 * This can only happen in the case of kmalloc() failure.
+		 * The filesystem's own lock is the authoritative lock,
+		 * so a failure to get the lock locally is not a disaster.
+		 * As long as the fs cannot reliably cancel locks (especially
+		 * in a low-memory situation), we're better off ignoring
+		 * this failure than trying to recover.
+		 */
+		log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p",
+			  (unsigned long long)op->info.number, file, fl);
+	}
+
+	rv = notify(flc, NULL, 0);
+	if (rv) {
+		/* XXX: We need to cancel the fs lock here: */
+		log_print("dlm_plock_callback: lock granted after lock request "
+			  "failed; dangling lock!\n");
+		goto out;
+	}
+
+out:
+	kfree(xop);
+	return rv;
+}
+
+int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
+		     struct file_lock *fl)
+{
+	struct dlm_ls *ls;
+	struct plock_op *op;
+	int rv;
+
+	ls = dlm_find_lockspace_local(lockspace);
+	if (!ls)
+		return -EINVAL;
+
+	op = kzalloc(sizeof(*op), GFP_KERNEL);
+	if (!op) {
+		rv = -ENOMEM;
+		goto out;
+	}
+
+	if (posix_lock_file_wait(file, fl) < 0)
+		log_error(ls, "dlm_posix_unlock: vfs unlock error %llx",
+			  (unsigned long long)number);
+
+	op->info.optype		= DLM_PLOCK_OP_UNLOCK;
+	op->info.pid		= fl->fl_pid;
+	op->info.fsid		= ls->ls_global_id;
+	op->info.number		= number;
+	op->info.start		= fl->fl_start;
+	op->info.end		= fl->fl_end;
+	if (fl->fl_lmops && fl->fl_lmops->fl_grant)
+		op->info.owner	= (__u64) fl->fl_pid;
+	else
+		op->info.owner	= (__u64)(long) fl->fl_owner;
+
+	send_op(op);
+	wait_event(recv_wq, (op->done != 0));
+
+	spin_lock(&ops_lock);
+	if (!list_empty(&op->list)) {
+		log_error(ls, "dlm_posix_unlock: op on list %llx",
+			  (unsigned long long)number);
+		list_del(&op->list);
+	}
+	spin_unlock(&ops_lock);
+
+	rv = op->info.rv;
+
+	if (rv == -ENOENT)
+		rv = 0;
+
+	kfree(op);
+out:
+	dlm_put_lockspace(ls);
+	return rv;
+}
+EXPORT_SYMBOL_GPL(dlm_posix_unlock);
+
+int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file,
+		  struct file_lock *fl)
+{
+	struct dlm_ls *ls;
+	struct plock_op *op;
+	int rv;
+
+	ls = dlm_find_lockspace_local(lockspace);
+	if (!ls)
+		return -EINVAL;
+
+	op = kzalloc(sizeof(*op), GFP_KERNEL);
+	if (!op) {
+		rv = -ENOMEM;
+		goto out;
+	}
+
+	op->info.optype		= DLM_PLOCK_OP_GET;
+	op->info.pid		= fl->fl_pid;
+	op->info.ex		= (fl->fl_type == F_WRLCK);
+	op->info.fsid		= ls->ls_global_id;
+	op->info.number		= number;
+	op->info.start		= fl->fl_start;
+	op->info.end		= fl->fl_end;
+	if (fl->fl_lmops && fl->fl_lmops->fl_grant)
+		op->info.owner	= (__u64) fl->fl_pid;
+	else
+		op->info.owner	= (__u64)(long) fl->fl_owner;
+
+	send_op(op);
+	wait_event(recv_wq, (op->done != 0));
+
+	spin_lock(&ops_lock);
+	if (!list_empty(&op->list)) {
+		log_error(ls, "dlm_posix_get: op on list %llx",
+			  (unsigned long long)number);
+		list_del(&op->list);
+	}
+	spin_unlock(&ops_lock);
+
+	/* info.rv from userspace is 1 for conflict, 0 for no-conflict,
+	   -ENOENT if there are no locks on the file */
+
+	rv = op->info.rv;
+
+	fl->fl_type = F_UNLCK;
+	if (rv == -ENOENT)
+		rv = 0;
+	else if (rv > 0) {
+		fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
+		fl->fl_pid = op->info.pid;
+		fl->fl_start = op->info.start;
+		fl->fl_end = op->info.end;
+		rv = 0;
+	}
+
+	kfree(op);
+out:
+	dlm_put_lockspace(ls);
+	return rv;
+}
+EXPORT_SYMBOL_GPL(dlm_posix_get);
+
+/* a read copies out one plock request from the send list */
+static ssize_t dev_read(struct file *file, char __user *u, size_t count,
+			loff_t *ppos)
+{
+	struct dlm_plock_info info;
+	struct plock_op *op = NULL;
+
+	if (count < sizeof(info))
+		return -EINVAL;
+
+	spin_lock(&ops_lock);
+	if (!list_empty(&send_list)) {
+		op = list_entry(send_list.next, struct plock_op, list);
+		list_move(&op->list, &recv_list);
+		memcpy(&info, &op->info, sizeof(info));
+	}
+	spin_unlock(&ops_lock);
+
+	if (!op)
+		return -EAGAIN;
+
+	if (copy_to_user(u, &info, sizeof(info)))
+		return -EFAULT;
+	return sizeof(info);
+}
+
+/* a write copies in one plock result that should match a plock_op
+   on the recv list */
+static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
+			 loff_t *ppos)
+{
+	struct dlm_plock_info info;
+	struct plock_op *op;
+	int found = 0;
+
+	if (count != sizeof(info))
+		return -EINVAL;
+
+	if (copy_from_user(&info, u, sizeof(info)))
+		return -EFAULT;
+
+	if (check_version(&info))
+		return -EINVAL;
+
+	spin_lock(&ops_lock);
+	list_for_each_entry(op, &recv_list, list) {
+		if (op->info.fsid == info.fsid && op->info.number == info.number &&
+		    op->info.owner == info.owner) {
+			list_del_init(&op->list);
+			found = 1;
+			op->done = 1;
+			memcpy(&op->info, &info, sizeof(info));
+			break;
+		}
+	}
+	spin_unlock(&ops_lock);
+
+	if (found) {
+		struct plock_xop *xop;
+		xop = (struct plock_xop *)op;
+		if (xop->callback)
+			count = dlm_plock_callback(op);
+		else
+			wake_up(&recv_wq);
+	} else
+		log_print("dev_write no op %x %llx", info.fsid,
+			  (unsigned long long)info.number);
+	return count;
+}
+
+static unsigned int dev_poll(struct file *file, poll_table *wait)
+{
+	unsigned int mask = 0;
+
+	poll_wait(file, &send_wq, wait);
+
+	spin_lock(&ops_lock);
+	if (!list_empty(&send_list))
+		mask = POLLIN | POLLRDNORM;
+	spin_unlock(&ops_lock);
+
+	return mask;
+}
+
+static const struct file_operations dev_fops = {
+	.read    = dev_read,
+	.write   = dev_write,
+	.poll    = dev_poll,
+	.owner   = THIS_MODULE
+};
+
+static struct miscdevice plock_dev_misc = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = DLM_PLOCK_MISC_NAME,
+	.fops = &dev_fops
+};
+
+int dlm_plock_init(void)
+{
+	int rv;
+
+	spin_lock_init(&ops_lock);
+	INIT_LIST_HEAD(&send_list);
+	INIT_LIST_HEAD(&recv_list);
+	init_waitqueue_head(&send_wq);
+	init_waitqueue_head(&recv_wq);
+
+	rv = misc_register(&plock_dev_misc);
+	if (rv)
+		log_print("dlm_plock_init: misc_register failed %d", rv);
+	return rv;
+}
+
+void dlm_plock_exit(void)
+{
+	if (misc_deregister(&plock_dev_misc) < 0)
+		log_print("dlm_plock_exit: misc_deregister failed");
+}
+