[deliverable/linux.git] / fs / lockd / clntlock.c

/*
 * linux/fs/lockd/clntlock.c
 *
 * Lock handling for the client side NLM implementation
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/time.h>
#include <linux/nfs_fs.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.h>
#include <linux/smp_lock.h>

#define NLMDBG_FACILITY		NLMDBG_CLIENT

/*
 * Local function prototypes
 */
static int			reclaimer(void *ptr);

/*
 * The following functions handle blocking and granting from the
 * client perspective.
 */

/*
 * This is the representation of a blocked client lock.
 */
struct nlm_wait {
	struct list_head	b_list;		/* linked list */
	wait_queue_head_t	b_wait;		/* where to wait on */
	struct nlm_host *	b_host;
	struct file_lock *	b_lock;		/* local file lock */
	unsigned short		b_reclaim;	/* got to reclaim lock */
	u32			b_status;	/* grant callback status */
};

static LIST_HEAD(nlm_blocked);

/*
 * Queue up a lock for blocking so that the GRANTED request can see it
 */
int nlmclnt_prepare_block(struct nlm_rqst *req, struct nlm_host *host, struct file_lock *fl)
{
	struct nlm_wait *block;

	BUG_ON(req->a_block != NULL);
	block = kmalloc(sizeof(*block), GFP_KERNEL);
	if (block == NULL)
		return -ENOMEM;
	block->b_host = host;
	block->b_lock = fl;
	init_waitqueue_head(&block->b_wait);
	block->b_status = NLM_LCK_BLOCKED;

	list_add(&block->b_list, &nlm_blocked);
	req->a_block = block;

	return 0;
}

void nlmclnt_finish_block(struct nlm_rqst *req)
{
	struct nlm_wait *block = req->a_block;

	if (block == NULL)
		return;
	req->a_block = NULL;
	list_del(&block->b_list);
	kfree(block);
}

/*
 * Block on a lock
 */
long nlmclnt_block(struct nlm_rqst *req, long timeout)
{
	struct nlm_wait	*block = req->a_block;
	long ret;

	/* A borken server might ask us to block even if we didn't
	 * request it. Just say no!
	 */
	if (!req->a_args.block)
		return -EAGAIN;

	/* Go to sleep waiting for GRANT callback. Some servers seem
	 * to lose callbacks, however, so we're going to poll from
	 * time to time just to make sure.
	 *
	 * For now, the retry frequency is pretty high; normally 
	 * a 1 minute timeout would do. See the comment before
	 * nlmclnt_lock for an explanation.
	 */
	ret = wait_event_interruptible_timeout(block->b_wait,
			block->b_status != NLM_LCK_BLOCKED,
			timeout);

	if (block->b_status != NLM_LCK_BLOCKED) {
		req->a_res.status = block->b_status;
		block->b_status = NLM_LCK_BLOCKED;
	}

	return ret;
}

/*
 * The server lockd has called us back to tell us the lock was granted
 */
u32
nlmclnt_grant(struct nlm_lock *lock)
{
	struct nlm_wait	*block;
	u32 res = nlm_lck_denied;

	/*
	 * Look up blocked request based on arguments. 
	 * Warning: must not use cookie to match it!
	 */
	list_for_each_entry(block, &nlm_blocked, b_list) {
		if (nlm_compare_locks(block->b_lock, &lock->fl)) {
			/* Alright, we found a lock. Set the return status
			 * and wake up the caller
			 */
			block->b_status = NLM_LCK_GRANTED;
			wake_up(&block->b_wait);
			res = nlm_granted;
		}
	}
	return res;
}

/*
 * The following procedures deal with the recovery of locks after a
 * server crash.
 */

/*
 * Mark the locks for reclaiming.
 * FIXME: In 2.5 we don't want to iterate through any global file_lock_list.
 *        Maintain NLM lock reclaiming lists in the nlm_host instead.
 */
static
void nlmclnt_mark_reclaim(struct nlm_host *host)
{
	struct file_lock *fl;
	struct inode *inode;
	struct list_head *tmp;

	list_for_each(tmp, &file_lock_list) {
		fl = list_entry(tmp, struct file_lock, fl_link);

		inode = fl->fl_file->f_dentry->d_inode;
		if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
			continue;
		if (fl->fl_u.nfs_fl.owner == NULL)
			continue;
		if (fl->fl_u.nfs_fl.owner->host != host)
			continue;
		if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
			continue;
		fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM;
	}
}

/*
 * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
 * that we mark locks for reclaiming, and that we bump the pseudo NSM state.
 */
static inline
void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
{
	host->h_monitored = 0;
	host->h_nsmstate = newstate;
	host->h_state++;
	host->h_nextrebind = 0;
	nlm_rebind_host(host);
	nlmclnt_mark_reclaim(host);
	dprintk("NLM: reclaiming locks for host %s", host->h_name);
}

/*
 * Reclaim all locks on server host. We do this by spawning a separate
 * reclaimer thread.
 */
void
nlmclnt_recovery(struct nlm_host *host, u32 newstate)
{
	if (host->h_reclaiming++) {
		if (host->h_nsmstate == newstate)
			return;
		nlmclnt_prepare_reclaim(host, newstate);
	} else {
		nlmclnt_prepare_reclaim(host, newstate);
		nlm_get_host(host);
		__module_get(THIS_MODULE);
		if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
			module_put(THIS_MODULE);
	}
}

static int
reclaimer(void *ptr)
{
	struct nlm_host	  *host = (struct nlm_host *) ptr;
	struct nlm_wait	  *block;
	struct list_head *tmp;
	struct file_lock *fl;
	struct inode *inode;

	daemonize("%s-reclaim", host->h_name);
	allow_signal(SIGKILL);

	/* This one ensures that our parent doesn't terminate while the
	 * reclaim is in progress */
	lock_kernel();
	lockd_up();

	/* First, reclaim all locks that have been marked. */
restart:
	list_for_each(tmp, &file_lock_list) {
		fl = list_entry(tmp, struct file_lock, fl_link);

		inode = fl->fl_file->f_dentry->d_inode;
		if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
			continue;
		if (fl->fl_u.nfs_fl.owner == NULL)
			continue;
		if (fl->fl_u.nfs_fl.owner->host != host)
			continue;
		if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
			continue;

		fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM;
		nlmclnt_reclaim(host, fl);
		if (signalled())
			break;
		goto restart;
	}

	host->h_reclaiming = 0;

	/* Now, wake up all processes that sleep on a blocked lock */
	list_for_each_entry(block, &nlm_blocked, b_list) {
		if (block->b_host == host) {
			block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
			wake_up(&block->b_wait);
		}
	}

	/* Release host handle after use */
	nlm_release_host(host);
	lockd_down();
	unlock_kernel();
	module_put_and_exit(0);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/lockd/clntlock.c
	3	*
	4	* Lock handling for the client side NLM implementation
	5	*
	6	* Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
	7	*/
	8
	9	#include <linux/module.h>
	10	#include <linux/types.h>
	11	#include <linux/time.h>
	12	#include <linux/nfs_fs.h>
	13	#include <linux/sunrpc/clnt.h>
	14	#include <linux/sunrpc/svc.h>
	15	#include <linux/lockd/lockd.h>
	16	#include <linux/smp_lock.h>
	17
	18	#define NLMDBG_FACILITY NLMDBG_CLIENT
	19
	20	/*
	21	* Local function prototypes
	22	*/
	23	static int reclaimer(void *ptr);
	24
	25	/*
	26	* The following functions handle blocking and granting from the
	27	* client perspective.
	28	*/
	29
	30	/*
	31	* This is the representation of a blocked client lock.
	32	*/
	33	struct nlm_wait {
4f15e2b1	34	struct list_head b_list; /* linked list */
1da177e4 LT	35	wait_queue_head_t b_wait; /* where to wait on */
	36	struct nlm_host * b_host;
	37	struct file_lock * b_lock; /* local file lock */
	38	unsigned short b_reclaim; /* got to reclaim lock */
	39	u32 b_status; /* grant callback status */
	40	};
	41
4f15e2b1	42	static LIST_HEAD(nlm_blocked);
1da177e4 LT	43
1da177e4 LT	44	/*
ecdbf769	45	* Queue up a lock for blocking so that the GRANTED request can see it
1da177e4	46	*/
ecdbf769 TM	47	int nlmclnt_prepare_block(struct nlm_rqst req, struct nlm_host host, struct file_lock *fl)
	48	{
	49	struct nlm_wait *block;
	50
	51	BUG_ON(req->a_block != NULL);
	52	block = kmalloc(sizeof(*block), GFP_KERNEL);
	53	if (block == NULL)
	54	return -ENOMEM;
	55	block->b_host = host;
	56	block->b_lock = fl;
	57	init_waitqueue_head(&block->b_wait);
	58	block->b_status = NLM_LCK_BLOCKED;
	59
	60	list_add(&block->b_list, &nlm_blocked);
	61	req->a_block = block;
	62
	63	return 0;
	64	}
	65
	66	void nlmclnt_finish_block(struct nlm_rqst *req)
1da177e4	67	{
ecdbf769 TM	68	struct nlm_wait *block = req->a_block;
	69
	70	if (block == NULL)
	71	return;
	72	req->a_block = NULL;
	73	list_del(&block->b_list);
	74	kfree(block);
	75	}
1da177e4	76
ecdbf769 TM	77	/*
	78	* Block on a lock
	79	*/
	80	long nlmclnt_block(struct nlm_rqst *req, long timeout)
	81	{
	82	struct nlm_wait *block = req->a_block;
	83	long ret;
1da177e4	84
ecdbf769 TM	85	/* A borken server might ask us to block even if we didn't
	86	* request it. Just say no!
	87	*/
	88	if (!req->a_args.block)
	89	return -EAGAIN;
1da177e4 LT	90
	91	/* Go to sleep waiting for GRANT callback. Some servers seem
	92	* to lose callbacks, however, so we're going to poll from
	93	* time to time just to make sure.
	94	*
	95	* For now, the retry frequency is pretty high; normally
	96	* a 1 minute timeout would do. See the comment before
	97	* nlmclnt_lock for an explanation.
	98	*/
ecdbf769 TM	99	ret = wait_event_interruptible_timeout(block->b_wait,
	100	block->b_status != NLM_LCK_BLOCKED,
	101	timeout);
1da177e4	102
ecdbf769 TM	103	if (block->b_status != NLM_LCK_BLOCKED) {
	104	req->a_res.status = block->b_status;
	105	block->b_status = NLM_LCK_BLOCKED;
1da177e4 LT	106	}
1da177e4 LT	107
ecdbf769	108	return ret;
1da177e4 LT	109	}
	110
	111	/*
	112	* The server lockd has called us back to tell us the lock was granted
	113	*/
	114	u32
	115	nlmclnt_grant(struct nlm_lock *lock)
	116	{
	117	struct nlm_wait *block;
ecdbf769	118	u32 res = nlm_lck_denied;
1da177e4 LT	119
	120	/*
	121	* Look up blocked request based on arguments.
	122	* Warning: must not use cookie to match it!
	123	*/
4f15e2b1	124	list_for_each_entry(block, &nlm_blocked, b_list) {
ecdbf769 TM	125	if (nlm_compare_locks(block->b_lock, &lock->fl)) {
	126	/* Alright, we found a lock. Set the return status
	127	* and wake up the caller
	128	*/
	129	block->b_status = NLM_LCK_GRANTED;
	130	wake_up(&block->b_wait);
	131	res = nlm_granted;
	132	}
1da177e4	133	}
ecdbf769	134	return res;
1da177e4 LT	135	}
	136
	137	/*
	138	* The following procedures deal with the recovery of locks after a
	139	* server crash.
	140	*/
	141
	142	/*
	143	* Mark the locks for reclaiming.
	144	* FIXME: In 2.5 we don't want to iterate through any global file_lock_list.
	145	* Maintain NLM lock reclaiming lists in the nlm_host instead.
	146	*/
	147	static
	148	void nlmclnt_mark_reclaim(struct nlm_host *host)
	149	{
	150	struct file_lock *fl;
	151	struct inode *inode;
	152	struct list_head *tmp;
	153
	154	list_for_each(tmp, &file_lock_list) {
	155	fl = list_entry(tmp, struct file_lock, fl_link);
	156
	157	inode = fl->fl_file->f_dentry->d_inode;
	158	if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
	159	continue;
9b5b1f5b TM	160	if (fl->fl_u.nfs_fl.owner == NULL)
9b5b1f5b TM	161	continue;
1da177e4 LT	162	if (fl->fl_u.nfs_fl.owner->host != host)
	163	continue;
	164	if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
	165	continue;
	166	fl->fl_u.nfs_fl.flags \|= NFS_LCK_RECLAIM;
	167	}
	168	}
	169
	170	/*
	171	* Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
	172	* that we mark locks for reclaiming, and that we bump the pseudo NSM state.
	173	*/
	174	static inline
	175	void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
	176	{
	177	host->h_monitored = 0;
	178	host->h_nsmstate = newstate;
	179	host->h_state++;
	180	host->h_nextrebind = 0;
	181	nlm_rebind_host(host);
	182	nlmclnt_mark_reclaim(host);
	183	dprintk("NLM: reclaiming locks for host %s", host->h_name);
	184	}
	185
	186	/*
	187	* Reclaim all locks on server host. We do this by spawning a separate
	188	* reclaimer thread.
	189	*/
	190	void
	191	nlmclnt_recovery(struct nlm_host *host, u32 newstate)
	192	{
	193	if (host->h_reclaiming++) {
	194	if (host->h_nsmstate == newstate)
	195	return;
	196	nlmclnt_prepare_reclaim(host, newstate);
	197	} else {
	198	nlmclnt_prepare_reclaim(host, newstate);
	199	nlm_get_host(host);
	200	__module_get(THIS_MODULE);
	201	if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
	202	module_put(THIS_MODULE);
	203	}
	204	}
	205
	206	static int
	207	reclaimer(void *ptr)
	208	{
	209	struct nlm_host host = (struct nlm_host ) ptr;
	210	struct nlm_wait *block;
	211	struct list_head *tmp;
	212	struct file_lock *fl;
	213	struct inode *inode;
	214
	215	daemonize("%s-reclaim", host->h_name);
	216	allow_signal(SIGKILL);
	217
	218	/* This one ensures that our parent doesn't terminate while the
	219	* reclaim is in progress */
	220	lock_kernel();
	221	lockd_up();
	222
	223	/* First, reclaim all locks that have been marked. */
	224	restart:
	225	list_for_each(tmp, &file_lock_list) {
226	fl = list_entry(tmp, struct file_lock, fl_link);
227
228	inode = fl->fl_file->f_dentry->d_inode;
229	if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
230	continue;
9b5b1f5b TM	231	if (fl->fl_u.nfs_fl.owner == NULL)
9b5b1f5b TM	232	continue;
1da177e4 LT	233	if (fl->fl_u.nfs_fl.owner->host != host)
	234	continue;
	235	if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
	236	continue;
	237
	238	fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM;
	239	nlmclnt_reclaim(host, fl);
	240	if (signalled())
	241	break;
	242	goto restart;
	243	}
	244
	245	host->h_reclaiming = 0;
	246
	247	/* Now, wake up all processes that sleep on a blocked lock */
4f15e2b1	248	list_for_each_entry(block, &nlm_blocked, b_list) {
1da177e4 LT	249	if (block->b_host == host) {
	250	block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
	251	wake_up(&block->b_wait);
	252	}
	253	}
	254
	255	/* Release host handle after use */
	256	nlm_release_host(host);
	257	lockd_down();
	258	unlock_kernel();
	259	module_put_and_exit(0);
	260	}