[mirror_ubuntu-artful-kernel.git] / fs / ocfs2 / dlm / userdlm.c

/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * userdlm.c
 *
 * Code which implements the kernel side of a minimal userspace
 * interface to our DLM.
 *
 * Many of the functions here are pared down versions of dlmglue.c
 * functions.
 *
 * Copyright (C) 2003, 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 */

#include <linux/signal.h>

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/crc32.h>


#include "cluster/nodemanager.h"
#include "cluster/heartbeat.h"
#include "cluster/tcp.h"

#include "dlmapi.h"

#include "userdlm.h"

#define MLOG_MASK_PREFIX ML_DLMFS
#include "cluster/masklog.h"

static inline int user_check_wait_flag(struct user_lock_res *lockres,
				       int flag)
{
	int ret;

	spin_lock(&lockres->l_lock);
	ret = lockres->l_flags & flag;
	spin_unlock(&lockres->l_lock);

	return ret;
}

static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)

{
	wait_event(lockres->l_event,
		   !user_check_wait_flag(lockres, USER_LOCK_BUSY));
}

static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)

{
	wait_event(lockres->l_event,
		   !user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
}

/* I heart container_of... */
static inline struct dlm_ctxt *
dlm_ctxt_from_user_lockres(struct user_lock_res *lockres)
{
	struct dlmfs_inode_private *ip;

	ip = container_of(lockres,
			  struct dlmfs_inode_private,
			  ip_lockres);
	return ip->ip_dlm;
}

static struct inode *
user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
{
	struct dlmfs_inode_private *ip;

	ip = container_of(lockres,
			  struct dlmfs_inode_private,
			  ip_lockres);
	return &ip->ip_vfs_inode;
}

static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
{
	spin_lock(&lockres->l_lock);
	lockres->l_flags &= ~USER_LOCK_BUSY;
	spin_unlock(&lockres->l_lock);
}

#define user_log_dlm_error(_func, _stat, _lockres) do {		\
	mlog(ML_ERROR, "Dlm error \"%s\" while calling %s on "	\
		"resource %s: %s\n", dlm_errname(_stat), _func,	\
		_lockres->l_name, dlm_errmsg(_stat));		\
} while (0)

/* WARNING: This function lives in a world where the only three lock
 * levels are EX, PR, and NL. It *will* have to be adjusted when more
 * lock types are added. */
static inline int user_highest_compat_lock_level(int level)
{
	int new_level = LKM_EXMODE;

	if (level == LKM_EXMODE)
		new_level = LKM_NLMODE;
	else if (level == LKM_PRMODE)
		new_level = LKM_PRMODE;
	return new_level;
}

static void user_ast(void *opaque)
{
	struct user_lock_res *lockres = opaque;
	struct dlm_lockstatus *lksb;

	mlog(0, "AST fired for lockres %s\n", lockres->l_name);

	spin_lock(&lockres->l_lock);

	lksb = &(lockres->l_lksb);
	if (lksb->status != DLM_NORMAL) {
		mlog(ML_ERROR, "lksb status value of %u on lockres %s\n",
		     lksb->status, lockres->l_name);
		spin_unlock(&lockres->l_lock);
		return;
	}

	mlog_bug_on_msg(lockres->l_requested == LKM_IVMODE,
			"Lockres %s, requested ivmode. flags 0x%x\n",
			lockres->l_name, lockres->l_flags);

	/* we're downconverting. */
	if (lockres->l_requested < lockres->l_level) {
		if (lockres->l_requested <=
		    user_highest_compat_lock_level(lockres->l_blocking)) {
			lockres->l_blocking = LKM_NLMODE;
			lockres->l_flags &= ~USER_LOCK_BLOCKED;
		}
	}

	lockres->l_level = lockres->l_requested;
	lockres->l_requested = LKM_IVMODE;
	lockres->l_flags |= USER_LOCK_ATTACHED;
	lockres->l_flags &= ~USER_LOCK_BUSY;

	spin_unlock(&lockres->l_lock);

	wake_up(&lockres->l_event);
}

static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
{
	struct inode *inode;
	inode = user_dlm_inode_from_user_lockres(lockres);
	if (!igrab(inode))
		BUG();
}

static void user_dlm_unblock_lock(void *opaque);

static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
{
	if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
		user_dlm_grab_inode_ref(lockres);

		INIT_WORK(&lockres->l_work, user_dlm_unblock_lock,
			  lockres);

		queue_work(user_dlm_worker, &lockres->l_work);
		lockres->l_flags |= USER_LOCK_QUEUED;
	}
}

static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
{
	int queue = 0;

	if (!(lockres->l_flags & USER_LOCK_BLOCKED))
		return;

	switch (lockres->l_blocking) {
	case LKM_EXMODE:
		if (!lockres->l_ex_holders && !lockres->l_ro_holders)
			queue = 1;
		break;
	case LKM_PRMODE:
		if (!lockres->l_ex_holders)
			queue = 1;
		break;
	default:
		BUG();
	}

	if (queue)
		__user_dlm_queue_lockres(lockres);
}

static void user_bast(void *opaque, int level)
{
	struct user_lock_res *lockres = opaque;

	mlog(0, "Blocking AST fired for lockres %s. Blocking level %d\n",
		lockres->l_name, level);

	spin_lock(&lockres->l_lock);
	lockres->l_flags |= USER_LOCK_BLOCKED;
	if (level > lockres->l_blocking)
		lockres->l_blocking = level;

	__user_dlm_queue_lockres(lockres);
	spin_unlock(&lockres->l_lock);

	wake_up(&lockres->l_event);
}

static void user_unlock_ast(void *opaque, enum dlm_status status)
{
	struct user_lock_res *lockres = opaque;

	mlog(0, "UNLOCK AST called on lock %s\n", lockres->l_name);

	if (status != DLM_NORMAL && status != DLM_CANCELGRANT)
		mlog(ML_ERROR, "Dlm returns status %d\n", status);

	spin_lock(&lockres->l_lock);
	/* The teardown flag gets set early during the unlock process,
	 * so test the cancel flag to make sure that this ast isn't
	 * for a concurrent cancel. */
	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN
	    && !(lockres->l_flags & USER_LOCK_IN_CANCEL)) {
		lockres->l_level = LKM_IVMODE;
	} else if (status == DLM_CANCELGRANT) {
		mlog(0, "Lock %s, cancel fails, flags 0x%x\n",
		     lockres->l_name, lockres->l_flags);
		/* We tried to cancel a convert request, but it was
		 * already granted. Don't clear the busy flag - the
		 * ast should've done this already. */
		BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
		lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
		goto out_noclear;
	} else {
		BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
		/* Cancel succeeded, we want to re-queue */
		mlog(0, "Lock %s, cancel succeeds, flags 0x%x\n",
		     lockres->l_name, lockres->l_flags);
		lockres->l_requested = LKM_IVMODE; /* cancel an
						    * upconvert
						    * request. */
		lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
		/* we want the unblock thread to look at it again
		 * now. */
		if (lockres->l_flags & USER_LOCK_BLOCKED)
			__user_dlm_queue_lockres(lockres);
	}

	lockres->l_flags &= ~USER_LOCK_BUSY;
out_noclear:
	spin_unlock(&lockres->l_lock);

	wake_up(&lockres->l_event);
}

static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
{
	struct inode *inode;
	inode = user_dlm_inode_from_user_lockres(lockres);
	iput(inode);
}

static void user_dlm_unblock_lock(void *opaque)
{
	int new_level, status;
	struct user_lock_res *lockres = (struct user_lock_res *) opaque;
	struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);

	mlog(0, "processing lockres %s\n", lockres->l_name);

	spin_lock(&lockres->l_lock);

	mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
			"Lockres %s, flags 0x%x\n",
			lockres->l_name, lockres->l_flags);

	/* notice that we don't clear USER_LOCK_BLOCKED here. If it's
	 * set, we want user_ast clear it. */
	lockres->l_flags &= ~USER_LOCK_QUEUED;

	/* It's valid to get here and no longer be blocked - if we get
	 * several basts in a row, we might be queued by the first
	 * one, the unblock thread might run and clear the queued
	 * flag, and finally we might get another bast which re-queues
	 * us before our ast for the downconvert is called. */
	if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
		mlog(0, "Lockres %s, flags 0x%x: queued but not blocking\n",
			lockres->l_name, lockres->l_flags);
		spin_unlock(&lockres->l_lock);
		goto drop_ref;
	}

	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
		mlog(0, "lock is in teardown so we do nothing\n");
		spin_unlock(&lockres->l_lock);
		goto drop_ref;
	}

	if (lockres->l_flags & USER_LOCK_BUSY) {
		mlog(0, "Cancel lock %s, flags 0x%x\n",
		     lockres->l_name, lockres->l_flags);

		if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
			spin_unlock(&lockres->l_lock);
			goto drop_ref;
		}

		lockres->l_flags |= USER_LOCK_IN_CANCEL;
		spin_unlock(&lockres->l_lock);

		status = dlmunlock(dlm,
				   &lockres->l_lksb,
				   LKM_CANCEL,
				   user_unlock_ast,
				   lockres);
		if (status != DLM_NORMAL)
			user_log_dlm_error("dlmunlock", status, lockres);
		goto drop_ref;
	}

	/* If there are still incompat holders, we can exit safely
	 * without worrying about re-queueing this lock as that will
	 * happen on the last call to user_cluster_unlock. */
	if ((lockres->l_blocking == LKM_EXMODE)
	    && (lockres->l_ex_holders || lockres->l_ro_holders)) {
		spin_unlock(&lockres->l_lock);
		mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
			lockres->l_ro_holders, lockres->l_ex_holders);
		goto drop_ref;
	}

	if ((lockres->l_blocking == LKM_PRMODE)
	    && lockres->l_ex_holders) {
		spin_unlock(&lockres->l_lock);
		mlog(0, "can't downconvert for pr: ex = %u\n",
			lockres->l_ex_holders);
		goto drop_ref;
	}

	/* yay, we can downconvert now. */
	new_level = user_highest_compat_lock_level(lockres->l_blocking);
	lockres->l_requested = new_level;
	lockres->l_flags |= USER_LOCK_BUSY;
	mlog(0, "Downconvert lock from %d to %d\n",
		lockres->l_level, new_level);
	spin_unlock(&lockres->l_lock);

	/* need lock downconvert request now... */
	status = dlmlock(dlm,
			 new_level,
			 &lockres->l_lksb,
			 LKM_CONVERT|LKM_VALBLK,
			 lockres->l_name,
			 user_ast,
			 lockres,
			 user_bast);
	if (status != DLM_NORMAL) {
		user_log_dlm_error("dlmlock", status, lockres);
		user_recover_from_dlm_error(lockres);
	}

drop_ref:
	user_dlm_drop_inode_ref(lockres);
}

static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
					int level)
{
	switch(level) {
	case LKM_EXMODE:
		lockres->l_ex_holders++;
		break;
	case LKM_PRMODE:
		lockres->l_ro_holders++;
		break;
	default:
		BUG();
	}
}

/* predict what lock level we'll be dropping down to on behalf
 * of another node, and return true if the currently wanted
 * level will be compatible with it. */
static inline int
user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
				  int wanted)
{
	BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));

	return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
}

int user_dlm_cluster_lock(struct user_lock_res *lockres,
			  int level,
			  int lkm_flags)
{
	int status, local_flags;
	struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);

	if (level != LKM_EXMODE &&
	    level != LKM_PRMODE) {
		mlog(ML_ERROR, "lockres %s: invalid request!\n",
		     lockres->l_name);
		status = -EINVAL;
		goto bail;
	}

	mlog(0, "lockres %s: asking for %s lock, passed flags = 0x%x\n",
		lockres->l_name,
		(level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
		lkm_flags);

again:
	if (signal_pending(current)) {
		status = -ERESTARTSYS;
		goto bail;
	}

	spin_lock(&lockres->l_lock);

	/* We only compare against the currently granted level
	 * here. If the lock is blocked waiting on a downconvert,
	 * we'll get caught below. */
	if ((lockres->l_flags & USER_LOCK_BUSY) &&
	    (level > lockres->l_level)) {
		/* is someone sitting in dlm_lock? If so, wait on
		 * them. */
		spin_unlock(&lockres->l_lock);

		user_wait_on_busy_lock(lockres);
		goto again;
	}

	if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
	    (!user_may_continue_on_blocked_lock(lockres, level))) {
		/* is the lock is currently blocked on behalf of
		 * another node */
		spin_unlock(&lockres->l_lock);

		user_wait_on_blocked_lock(lockres);
		goto again;
	}

	if (level > lockres->l_level) {
		local_flags = lkm_flags | LKM_VALBLK;
		if (lockres->l_level != LKM_IVMODE)
			local_flags |= LKM_CONVERT;

		lockres->l_requested = level;
		lockres->l_flags |= USER_LOCK_BUSY;
		spin_unlock(&lockres->l_lock);

		BUG_ON(level == LKM_IVMODE);
		BUG_ON(level == LKM_NLMODE);

		mlog(0, "lock %s, get lock from %d to level = %d\n",
			lockres->l_name, lockres->l_level, level);

		/* call dlm_lock to upgrade lock now */
		status = dlmlock(dlm,
				 level,
				 &lockres->l_lksb,
				 local_flags,
				 lockres->l_name,
				 user_ast,
				 lockres,
				 user_bast);
		if (status != DLM_NORMAL) {
			if ((lkm_flags & LKM_NOQUEUE) &&
			    (status == DLM_NOTQUEUED))
				status = -EAGAIN;
			else {
				user_log_dlm_error("dlmlock", status, lockres);
				status = -EINVAL;
			}
			user_recover_from_dlm_error(lockres);
			goto bail;
		}

		mlog(0, "lock %s, successfull return from dlmlock\n",
			lockres->l_name);

		user_wait_on_busy_lock(lockres);
		goto again;
	}

	user_dlm_inc_holders(lockres, level);
	spin_unlock(&lockres->l_lock);

	mlog(0, "lockres %s: Got %s lock!\n", lockres->l_name,
		(level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");

	status = 0;
bail:
	return status;
}

static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
					int level)
{
	switch(level) {
	case LKM_EXMODE:
		BUG_ON(!lockres->l_ex_holders);
		lockres->l_ex_holders--;
		break;
	case LKM_PRMODE:
		BUG_ON(!lockres->l_ro_holders);
		lockres->l_ro_holders--;
		break;
	default:
		BUG();
	}
}

void user_dlm_cluster_unlock(struct user_lock_res *lockres,
			     int level)
{
	if (level != LKM_EXMODE &&
	    level != LKM_PRMODE) {
		mlog(ML_ERROR, "lockres %s: invalid request!\n", lockres->l_name);
		return;
	}

	mlog(0, "lockres %s: dropping %s lock\n", lockres->l_name,
		(level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");

	spin_lock(&lockres->l_lock);
	user_dlm_dec_holders(lockres, level);
	__user_dlm_cond_queue_lockres(lockres);
	spin_unlock(&lockres->l_lock);
}

void user_dlm_write_lvb(struct inode *inode,
			const char *val,
			unsigned int len)
{
	struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
	char *lvb = lockres->l_lksb.lvb;

	BUG_ON(len > DLM_LVB_LEN);

	spin_lock(&lockres->l_lock);

	BUG_ON(lockres->l_level < LKM_EXMODE);
	memcpy(lvb, val, len);

	spin_unlock(&lockres->l_lock);
}

void user_dlm_read_lvb(struct inode *inode,
		       char *val,
		       unsigned int len)
{
	struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
	char *lvb = lockres->l_lksb.lvb;

	BUG_ON(len > DLM_LVB_LEN);

	spin_lock(&lockres->l_lock);

	BUG_ON(lockres->l_level < LKM_PRMODE);
	memcpy(val, lvb, len);

	spin_unlock(&lockres->l_lock);
}

void user_dlm_lock_res_init(struct user_lock_res *lockres,
			    struct dentry *dentry)
{
	memset(lockres, 0, sizeof(*lockres));

	spin_lock_init(&lockres->l_lock);
	init_waitqueue_head(&lockres->l_event);
	lockres->l_level = LKM_IVMODE;
	lockres->l_requested = LKM_IVMODE;
	lockres->l_blocking = LKM_IVMODE;

	/* should have been checked before getting here. */
	BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);

	memcpy(lockres->l_name,
	       dentry->d_name.name,
	       dentry->d_name.len);
}

int user_dlm_destroy_lock(struct user_lock_res *lockres)
{
	int status = -EBUSY;
	struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);

	mlog(0, "asked to destroy %s\n", lockres->l_name);

	spin_lock(&lockres->l_lock);
	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
		mlog(0, "Lock is already torn down\n");
		spin_unlock(&lockres->l_lock);
		return 0;
	}

	lockres->l_flags |= USER_LOCK_IN_TEARDOWN;

	while (lockres->l_flags & USER_LOCK_BUSY) {
		spin_unlock(&lockres->l_lock);

		mlog(0, "lock %s is busy\n", lockres->l_name);

		user_wait_on_busy_lock(lockres);

		spin_lock(&lockres->l_lock);
	}

	if (lockres->l_ro_holders || lockres->l_ex_holders) {
		spin_unlock(&lockres->l_lock);
		mlog(0, "lock %s has holders\n", lockres->l_name);
		goto bail;
	}

	status = 0;
	if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
		spin_unlock(&lockres->l_lock);
		mlog(0, "lock %s is not attached\n", lockres->l_name);
		goto bail;
	}

	lockres->l_flags &= ~USER_LOCK_ATTACHED;
	lockres->l_flags |= USER_LOCK_BUSY;
	spin_unlock(&lockres->l_lock);

	mlog(0, "unlocking lockres %s\n", lockres->l_name);
	status = dlmunlock(dlm,
			   &lockres->l_lksb,
			   LKM_VALBLK,
			   user_unlock_ast,
			   lockres);
	if (status != DLM_NORMAL) {
		user_log_dlm_error("dlmunlock", status, lockres);
		status = -EINVAL;
		goto bail;
	}

	user_wait_on_busy_lock(lockres);

	status = 0;
bail:
	return status;
}

struct dlm_ctxt *user_dlm_register_context(struct qstr *name)
{
	struct dlm_ctxt *dlm;
	u32 dlm_key;
	char *domain;

	domain = kmalloc(name->len + 1, GFP_NOFS);
	if (!domain) {
		mlog_errno(-ENOMEM);
		return ERR_PTR(-ENOMEM);
	}

	dlm_key = crc32_le(0, name->name, name->len);

	snprintf(domain, name->len + 1, "%.*s", name->len, name->name);

	dlm = dlm_register_domain(domain, dlm_key);
	if (IS_ERR(dlm))
		mlog_errno(PTR_ERR(dlm));

	kfree(domain);
	return dlm;
}

void user_dlm_unregister_context(struct dlm_ctxt *dlm)
{
	dlm_unregister_domain(dlm);
}
Commit	Line	Data
8df08c89 MF	1	/* -- mode: c; c-basic-offset: 8; --
	2	* vim: noexpandtab sw=8 ts=8 sts=0:
	3	*
	4	* userdlm.c
	5	*
	6	* Code which implements the kernel side of a minimal userspace
	7	* interface to our DLM.
	8	*
	9	* Many of the functions here are pared down versions of dlmglue.c
	10	* functions.
	11	*
	12	* Copyright (C) 2003, 2004 Oracle. All rights reserved.
	13	*
	14	* This program is free software; you can redistribute it and/or
	15	* modify it under the terms of the GNU General Public
	16	* License as published by the Free Software Foundation; either
	17	* version 2 of the License, or (at your option) any later version.
	18	*
	19	* This program is distributed in the hope that it will be useful,
	20	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	22	* General Public License for more details.
	23	*
	24	* You should have received a copy of the GNU General Public
	25	* License along with this program; if not, write to the
	26	* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	27	* Boston, MA 021110-1307, USA.
	28	*/
	29
aee93ac4	30	#include <linux/signal.h>
8df08c89 MF	31
	32	#include <linux/module.h>
	33	#include <linux/fs.h>
	34	#include <linux/types.h>
	35	#include <linux/crc32.h>
	36
	37
	38	#include "cluster/nodemanager.h"
	39	#include "cluster/heartbeat.h"
	40	#include "cluster/tcp.h"
	41
	42	#include "dlmapi.h"
	43
	44	#include "userdlm.h"
	45
	46	#define MLOG_MASK_PREFIX ML_DLMFS
	47	#include "cluster/masklog.h"
	48
	49	static inline int user_check_wait_flag(struct user_lock_res *lockres,
	50	int flag)
	51	{
	52	int ret;
	53
	54	spin_lock(&lockres->l_lock);
	55	ret = lockres->l_flags & flag;
	56	spin_unlock(&lockres->l_lock);
	57
	58	return ret;
	59	}
	60
	61	static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)
	62
	63	{
	64	wait_event(lockres->l_event,
	65	!user_check_wait_flag(lockres, USER_LOCK_BUSY));
	66	}
	67
	68	static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)
	69
	70	{
	71	wait_event(lockres->l_event,
	72	!user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
	73	}
	74
	75	/* I heart container_of... */
	76	static inline struct dlm_ctxt *
	77	dlm_ctxt_from_user_lockres(struct user_lock_res *lockres)
	78	{
	79	struct dlmfs_inode_private *ip;
	80
	81	ip = container_of(lockres,
	82	struct dlmfs_inode_private,
	83	ip_lockres);
	84	return ip->ip_dlm;
	85	}
	86
	87	static struct inode *
	88	user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
	89	{
	90	struct dlmfs_inode_private *ip;
	91
	92	ip = container_of(lockres,
	93	struct dlmfs_inode_private,
	94	ip_lockres);
95	return &ip->ip_vfs_inode;
96	}
97
98	static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
99	{
100	spin_lock(&lockres->l_lock);
101	lockres->l_flags &= ~USER_LOCK_BUSY;
102	spin_unlock(&lockres->l_lock);
103	}
104
105	#define user_log_dlm_error(_func, _stat, _lockres) do { \
106	mlog(ML_ERROR, "Dlm error \"%s\" while calling %s on " \
107	"resource %s: %s\n", dlm_errname(_stat), _func, \
108	_lockres->l_name, dlm_errmsg(_stat)); \
109	} while (0)
110
111	/* WARNING: This function lives in a world where the only three lock
112	* levels are EX, PR, and NL. It will have to be adjusted when more
113	* lock types are added. */
114	static inline int user_highest_compat_lock_level(int level)
115	{
116	int new_level = LKM_EXMODE;
117
118	if (level == LKM_EXMODE)
119	new_level = LKM_NLMODE;
120	else if (level == LKM_PRMODE)
121	new_level = LKM_PRMODE;
122	return new_level;
123	}
124
125	static void user_ast(void *opaque)
126	{
127	struct user_lock_res *lockres = opaque;
128	struct dlm_lockstatus *lksb;
129
130	mlog(0, "AST fired for lockres %s\n", lockres->l_name);
131
132	spin_lock(&lockres->l_lock);
133
134	lksb = &(lockres->l_lksb);
135	if (lksb->status != DLM_NORMAL) {
136	mlog(ML_ERROR, "lksb status value of %u on lockres %s\n",
137	lksb->status, lockres->l_name);
138	spin_unlock(&lockres->l_lock);
139	return;
140	}
141
cc6eb725 MF	142	mlog_bug_on_msg(lockres->l_requested == LKM_IVMODE,
	143	"Lockres %s, requested ivmode. flags 0x%x\n",
	144	lockres->l_name, lockres->l_flags);
	145
8df08c89 MF	146	/* we're downconverting. */
	147	if (lockres->l_requested < lockres->l_level) {
	148	if (lockres->l_requested <=
	149	user_highest_compat_lock_level(lockres->l_blocking)) {
	150	lockres->l_blocking = LKM_NLMODE;
	151	lockres->l_flags &= ~USER_LOCK_BLOCKED;
	152	}
	153	}
	154
	155	lockres->l_level = lockres->l_requested;
	156	lockres->l_requested = LKM_IVMODE;
	157	lockres->l_flags \|= USER_LOCK_ATTACHED;
	158	lockres->l_flags &= ~USER_LOCK_BUSY;
	159
	160	spin_unlock(&lockres->l_lock);
	161
	162	wake_up(&lockres->l_event);
	163	}
	164
	165	static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
	166	{
	167	struct inode *inode;
	168	inode = user_dlm_inode_from_user_lockres(lockres);
	169	if (!igrab(inode))
	170	BUG();
	171	}
	172
	173	static void user_dlm_unblock_lock(void *opaque);
	174
	175	static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
	176	{
	177	if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
	178	user_dlm_grab_inode_ref(lockres);
	179
	180	INIT_WORK(&lockres->l_work, user_dlm_unblock_lock,
	181	lockres);
	182
	183	queue_work(user_dlm_worker, &lockres->l_work);
	184	lockres->l_flags \|= USER_LOCK_QUEUED;
	185	}
	186	}
	187
	188	static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
	189	{
	190	int queue = 0;
	191
	192	if (!(lockres->l_flags & USER_LOCK_BLOCKED))
	193	return;
	194
	195	switch (lockres->l_blocking) {
	196	case LKM_EXMODE:
	197	if (!lockres->l_ex_holders && !lockres->l_ro_holders)
	198	queue = 1;
	199	break;
	200	case LKM_PRMODE:
	201	if (!lockres->l_ex_holders)
	202	queue = 1;
	203	break;
	204	default:
	205	BUG();
	206	}
	207
	208	if (queue)
	209	__user_dlm_queue_lockres(lockres);
210	}
211
212	static void user_bast(void *opaque, int level)
213	{
214	struct user_lock_res *lockres = opaque;
215
216	mlog(0, "Blocking AST fired for lockres %s. Blocking level %d\n",
217	lockres->l_name, level);
218
219	spin_lock(&lockres->l_lock);
220	lockres->l_flags \|= USER_LOCK_BLOCKED;
221	if (level > lockres->l_blocking)
222	lockres->l_blocking = level;
223
224	__user_dlm_queue_lockres(lockres);
225	spin_unlock(&lockres->l_lock);
226
227	wake_up(&lockres->l_event);
228	}
229
230	static void user_unlock_ast(void *opaque, enum dlm_status status)
231	{
232	struct user_lock_res *lockres = opaque;
233
234	mlog(0, "UNLOCK AST called on lock %s\n", lockres->l_name);
235
f43e6918	236	if (status != DLM_NORMAL && status != DLM_CANCELGRANT)
8df08c89 MF	237	mlog(ML_ERROR, "Dlm returns status %d\n", status);
	238
	239	spin_lock(&lockres->l_lock);
2cd98885 MF	240	/* The teardown flag gets set early during the unlock process,
	241	* so test the cancel flag to make sure that this ast isn't
	242	* for a concurrent cancel. */
	243	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN
	244	&& !(lockres->l_flags & USER_LOCK_IN_CANCEL)) {
8df08c89	245	lockres->l_level = LKM_IVMODE;
2cd98885	246	} else if (status == DLM_CANCELGRANT) {
f43e6918 MF	247	mlog(0, "Lock %s, cancel fails, flags 0x%x\n",
	248	lockres->l_name, lockres->l_flags);
	249	/* We tried to cancel a convert request, but it was
	250	* already granted. Don't clear the busy flag - the
	251	* ast should've done this already. */
	252	BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
	253	lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
	254	goto out_noclear;
	255	} else {
	256	BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
	257	/* Cancel succeeded, we want to re-queue */
	258	mlog(0, "Lock %s, cancel succeeds, flags 0x%x\n",
	259	lockres->l_name, lockres->l_flags);
8df08c89 MF	260	lockres->l_requested = LKM_IVMODE; /* cancel an
	261	* upconvert
	262	* request. */
	263	lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
	264	/* we want the unblock thread to look at it again
	265	* now. */
f43e6918 MF	266	if (lockres->l_flags & USER_LOCK_BLOCKED)
f43e6918 MF	267	__user_dlm_queue_lockres(lockres);
8df08c89 MF	268	}
	269
	270	lockres->l_flags &= ~USER_LOCK_BUSY;
f43e6918	271	out_noclear:
8df08c89 MF	272	spin_unlock(&lockres->l_lock);
	273
	274	wake_up(&lockres->l_event);
	275	}
	276
	277	static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
	278	{
	279	struct inode *inode;
	280	inode = user_dlm_inode_from_user_lockres(lockres);
	281	iput(inode);
	282	}
	283
	284	static void user_dlm_unblock_lock(void *opaque)
	285	{
	286	int new_level, status;
	287	struct user_lock_res lockres = (struct user_lock_res ) opaque;
	288	struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
	289
	290	mlog(0, "processing lockres %s\n", lockres->l_name);
	291
	292	spin_lock(&lockres->l_lock);
	293
1f7bc828 MF	294	mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
	295	"Lockres %s, flags 0x%x\n",
	296	lockres->l_name, lockres->l_flags);
8df08c89	297
1f7bc828 MF	298	/* notice that we don't clear USER_LOCK_BLOCKED here. If it's
1f7bc828 MF	299	* set, we want user_ast clear it. */
8df08c89 MF	300	lockres->l_flags &= ~USER_LOCK_QUEUED;
8df08c89 MF	301
1f7bc828 MF	302	/* It's valid to get here and no longer be blocked - if we get
	303	* several basts in a row, we might be queued by the first
	304	* one, the unblock thread might run and clear the queued
	305	* flag, and finally we might get another bast which re-queues
	306	* us before our ast for the downconvert is called. */
	307	if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
	308	mlog(0, "Lockres %s, flags 0x%x: queued but not blocking\n",
	309	lockres->l_name, lockres->l_flags);
	310	spin_unlock(&lockres->l_lock);
	311	goto drop_ref;
	312	}
	313
8df08c89 MF	314	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
	315	mlog(0, "lock is in teardown so we do nothing\n");
	316	spin_unlock(&lockres->l_lock);
	317	goto drop_ref;
	318	}
	319
	320	if (lockres->l_flags & USER_LOCK_BUSY) {
f43e6918 MF	321	mlog(0, "Cancel lock %s, flags 0x%x\n",
	322	lockres->l_name, lockres->l_flags);
	323
8df08c89 MF	324	if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
	325	spin_unlock(&lockres->l_lock);
	326	goto drop_ref;
	327	}
	328
	329	lockres->l_flags \|= USER_LOCK_IN_CANCEL;
	330	spin_unlock(&lockres->l_lock);
	331
	332	status = dlmunlock(dlm,
	333	&lockres->l_lksb,
	334	LKM_CANCEL,
	335	user_unlock_ast,
	336	lockres);
f43e6918	337	if (status != DLM_NORMAL)
8df08c89 MF	338	user_log_dlm_error("dlmunlock", status, lockres);
	339	goto drop_ref;
	340	}
	341
	342	/* If there are still incompat holders, we can exit safely
	343	* without worrying about re-queueing this lock as that will
	344	* happen on the last call to user_cluster_unlock. */
	345	if ((lockres->l_blocking == LKM_EXMODE)
	346	&& (lockres->l_ex_holders \|\| lockres->l_ro_holders)) {
	347	spin_unlock(&lockres->l_lock);
	348	mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
	349	lockres->l_ro_holders, lockres->l_ex_holders);
	350	goto drop_ref;
	351	}
	352
	353	if ((lockres->l_blocking == LKM_PRMODE)
	354	&& lockres->l_ex_holders) {
	355	spin_unlock(&lockres->l_lock);
	356	mlog(0, "can't downconvert for pr: ex = %u\n",
	357	lockres->l_ex_holders);
	358	goto drop_ref;
	359	}
	360
	361	/* yay, we can downconvert now. */
	362	new_level = user_highest_compat_lock_level(lockres->l_blocking);
	363	lockres->l_requested = new_level;
	364	lockres->l_flags \|= USER_LOCK_BUSY;
	365	mlog(0, "Downconvert lock from %d to %d\n",
	366	lockres->l_level, new_level);
	367	spin_unlock(&lockres->l_lock);
	368
	369	/* need lock downconvert request now... */
	370	status = dlmlock(dlm,
	371	new_level,
	372	&lockres->l_lksb,
	373	LKM_CONVERT\|LKM_VALBLK,
	374	lockres->l_name,
	375	user_ast,
	376	lockres,
	377	user_bast);
	378	if (status != DLM_NORMAL) {
	379	user_log_dlm_error("dlmlock", status, lockres);
	380	user_recover_from_dlm_error(lockres);
	381	}
	382
	383	drop_ref:
	384	user_dlm_drop_inode_ref(lockres);
	385	}
	386
	387	static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
	388	int level)
	389	{
	390	switch(level) {
	391	case LKM_EXMODE:
	392	lockres->l_ex_holders++;
	393	break;
	394	case LKM_PRMODE:
	395	lockres->l_ro_holders++;
	396	break;
	397	default:
	398	BUG();
	399	}
	400	}
	401
402	/* predict what lock level we'll be dropping down to on behalf
403	* of another node, and return true if the currently wanted
404	* level will be compatible with it. */
405	static inline int
406	user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
407	int wanted)
408	{
409	BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
410
411	return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
412	}
413
414	int user_dlm_cluster_lock(struct user_lock_res *lockres,
415	int level,
416	int lkm_flags)
417	{
418	int status, local_flags;
419	struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
420
421	if (level != LKM_EXMODE &&
422	level != LKM_PRMODE) {
423	mlog(ML_ERROR, "lockres %s: invalid request!\n",
424	lockres->l_name);
425	status = -EINVAL;
426	goto bail;
427	}
428
429	mlog(0, "lockres %s: asking for %s lock, passed flags = 0x%x\n",
430	lockres->l_name,
431	(level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
432	lkm_flags);
433
434	again:
435	if (signal_pending(current)) {
436	status = -ERESTARTSYS;
437	goto bail;
438	}
439
440	spin_lock(&lockres->l_lock);
441
442	/* We only compare against the currently granted level
443	* here. If the lock is blocked waiting on a downconvert,
444	* we'll get caught below. */
445	if ((lockres->l_flags & USER_LOCK_BUSY) &&
446	(level > lockres->l_level)) {
447	/* is someone sitting in dlm_lock? If so, wait on
448	* them. */
449	spin_unlock(&lockres->l_lock);
450
451	user_wait_on_busy_lock(lockres);
452	goto again;
453	}
454
455	if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
456	(!user_may_continue_on_blocked_lock(lockres, level))) {
457	/* is the lock is currently blocked on behalf of
458	* another node */
459	spin_unlock(&lockres->l_lock);
460
461	user_wait_on_blocked_lock(lockres);
462	goto again;
463	}
464
465	if (level > lockres->l_level) {
466	local_flags = lkm_flags \| LKM_VALBLK;
467	if (lockres->l_level != LKM_IVMODE)
468	local_flags \|= LKM_CONVERT;
469
470	lockres->l_requested = level;
471	lockres->l_flags \|= USER_LOCK_BUSY;
472	spin_unlock(&lockres->l_lock);
473
474	BUG_ON(level == LKM_IVMODE);
475	BUG_ON(level == LKM_NLMODE);
476
477	mlog(0, "lock %s, get lock from %d to level = %d\n",
478	lockres->l_name, lockres->l_level, level);
479
480	/* call dlm_lock to upgrade lock now */
481	status = dlmlock(dlm,
482	level,
483	&lockres->l_lksb,
484	local_flags,
485	lockres->l_name,
486	user_ast,
487	lockres,
488	user_bast);
489	if (status != DLM_NORMAL) {
490	if ((lkm_flags & LKM_NOQUEUE) &&
491	(status == DLM_NOTQUEUED))
492	status = -EAGAIN;
493	else {
494	user_log_dlm_error("dlmlock", status, lockres);
495	status = -EINVAL;
496	}
497	user_recover_from_dlm_error(lockres);
498	goto bail;
499	}
500
501	mlog(0, "lock %s, successfull return from dlmlock\n",
502	lockres->l_name);
503
504	user_wait_on_busy_lock(lockres);
505	goto again;
506	}
507
508	user_dlm_inc_holders(lockres, level);
509	spin_unlock(&lockres->l_lock);
510
511	mlog(0, "lockres %s: Got %s lock!\n", lockres->l_name,
512	(level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
513
514	status = 0;
515	bail:
516	return status;
517	}
518
519	static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
520	int level)
521	{
522	switch(level) {
523	case LKM_EXMODE:
524	BUG_ON(!lockres->l_ex_holders);
525	lockres->l_ex_holders--;
526	break;
527	case LKM_PRMODE:
528	BUG_ON(!lockres->l_ro_holders);
529	lockres->l_ro_holders--;
530	break;
531	default:
532	BUG();
533	}
534	}
535
536	void user_dlm_cluster_unlock(struct user_lock_res *lockres,
537	int level)
538	{
539	if (level != LKM_EXMODE &&
540	level != LKM_PRMODE) {
541	mlog(ML_ERROR, "lockres %s: invalid request!\n", lockres->l_name);
542	return;
543	}
544
545	mlog(0, "lockres %s: dropping %s lock\n", lockres->l_name,
546	(level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE");
547
548	spin_lock(&lockres->l_lock);
549	user_dlm_dec_holders(lockres, level);
550	__user_dlm_cond_queue_lockres(lockres);
551	spin_unlock(&lockres->l_lock);
552	}
553
554	void user_dlm_write_lvb(struct inode *inode,
555	const char *val,
556	unsigned int len)
557	{
558	struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
559	char *lvb = lockres->l_lksb.lvb;
560
561	BUG_ON(len > DLM_LVB_LEN);
562
563	spin_lock(&lockres->l_lock);
564
565	BUG_ON(lockres->l_level < LKM_EXMODE);
566	memcpy(lvb, val, len);
567
568	spin_unlock(&lockres->l_lock);
569	}
570
571	void user_dlm_read_lvb(struct inode *inode,
572	char *val,
573	unsigned int len)
574	{
575	struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
576	char *lvb = lockres->l_lksb.lvb;
577
578	BUG_ON(len > DLM_LVB_LEN);
579
580	spin_lock(&lockres->l_lock);
581
582	BUG_ON(lockres->l_level < LKM_PRMODE);
583	memcpy(val, lvb, len);
584
585	spin_unlock(&lockres->l_lock);
586	}
587
588	void user_dlm_lock_res_init(struct user_lock_res *lockres,
589	struct dentry *dentry)
590	{
591	memset(lockres, 0, sizeof(*lockres));
592
593	spin_lock_init(&lockres->l_lock);
594	init_waitqueue_head(&lockres->l_event);
595	lockres->l_level = LKM_IVMODE;
596	lockres->l_requested = LKM_IVMODE;
597	lockres->l_blocking = LKM_IVMODE;
598
599	/* should have been checked before getting here. */
600	BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
601
602	memcpy(lockres->l_name,
603	dentry->d_name.name,
604	dentry->d_name.len);
605	}
606
607	int user_dlm_destroy_lock(struct user_lock_res *lockres)
608	{
609	int status = -EBUSY;
610	struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
611
612	mlog(0, "asked to destroy %s\n", lockres->l_name);
613
614	spin_lock(&lockres->l_lock);
2cd98885 MF	615	if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
	616	mlog(0, "Lock is already torn down\n");
	617	spin_unlock(&lockres->l_lock);
	618	return 0;
	619	}
	620
	621	lockres->l_flags \|= USER_LOCK_IN_TEARDOWN;
	622
8df08c89 MF	623	while (lockres->l_flags & USER_LOCK_BUSY) {
	624	spin_unlock(&lockres->l_lock);
	625
	626	mlog(0, "lock %s is busy\n", lockres->l_name);
	627
	628	user_wait_on_busy_lock(lockres);
	629
	630	spin_lock(&lockres->l_lock);
	631	}
	632
	633	if (lockres->l_ro_holders \|\| lockres->l_ex_holders) {
	634	spin_unlock(&lockres->l_lock);
	635	mlog(0, "lock %s has holders\n", lockres->l_name);
	636	goto bail;
	637	}
	638
	639	status = 0;
	640	if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
	641	spin_unlock(&lockres->l_lock);
	642	mlog(0, "lock %s is not attached\n", lockres->l_name);
	643	goto bail;
	644	}
	645
	646	lockres->l_flags &= ~USER_LOCK_ATTACHED;
	647	lockres->l_flags \|= USER_LOCK_BUSY;
8df08c89 MF	648	spin_unlock(&lockres->l_lock);
	649
	650	mlog(0, "unlocking lockres %s\n", lockres->l_name);
	651	status = dlmunlock(dlm,
	652	&lockres->l_lksb,
	653	LKM_VALBLK,
	654	user_unlock_ast,
	655	lockres);
	656	if (status != DLM_NORMAL) {
	657	user_log_dlm_error("dlmunlock", status, lockres);
	658	status = -EINVAL;
	659	goto bail;
	660	}
	661
	662	user_wait_on_busy_lock(lockres);
	663
	664	status = 0;
	665	bail:
	666	return status;
	667	}
	668
	669	struct dlm_ctxt user_dlm_register_context(struct qstr name)
	670	{
	671	struct dlm_ctxt *dlm;
	672	u32 dlm_key;
	673	char *domain;
	674
ad8100e0	675	domain = kmalloc(name->len + 1, GFP_NOFS);
8df08c89 MF	676	if (!domain) {
	677	mlog_errno(-ENOMEM);
	678	return ERR_PTR(-ENOMEM);
	679	}
	680
	681	dlm_key = crc32_le(0, name->name, name->len);
	682
	683	snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
	684
	685	dlm = dlm_register_domain(domain, dlm_key);
	686	if (IS_ERR(dlm))
	687	mlog_errno(PTR_ERR(dlm));
	688
	689	kfree(domain);
	690	return dlm;
	691	}
	692
	693	void user_dlm_unregister_context(struct dlm_ctxt *dlm)
	694	{
	695	dlm_unregister_domain(dlm);
	696	}