[linux-2.6-block.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>
#include <linux/kthread.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 */
	__be32			b_status;	/* grant callback status */
};

static LIST_HEAD(nlm_blocked);

/**
 * nlmclnt_init - Set up per-NFS mount point lockd data structures
 * @nlm_init: pointer to arguments structure
 *
 * Returns pointer to an appropriate nlm_host struct,
 * or an ERR_PTR value.
 */
struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
{
	struct nlm_host *host;
	u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
	int status;

	status = lockd_up();
	if (status < 0)
		return ERR_PTR(status);

	host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
				   nlm_init->protocol, nlm_version,
				   nlm_init->hostname, nlm_init->noresvport);
	if (host == NULL) {
		lockd_down();
		return ERR_PTR(-ENOLCK);
	}

	return host;
}
EXPORT_SYMBOL_GPL(nlmclnt_init);

/**
 * nlmclnt_done - Release resources allocated by nlmclnt_init()
 * @host: nlm_host structure reserved by nlmclnt_init()
 *
 */
void nlmclnt_done(struct nlm_host *host)
{
	nlm_release_host(host);
	lockd_down();
}
EXPORT_SYMBOL_GPL(nlmclnt_done);

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

	block = kmalloc(sizeof(*block), GFP_KERNEL);
	if (block != NULL) {
		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);
	}
	return block;
}

void nlmclnt_finish_block(struct nlm_wait *block)
{
	if (block == NULL)
		return;
	list_del(&block->b_list);
	kfree(block);
}

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

	/* A borken server might ask us to block even if we didn't
	 * request it. Just say no!
	 */
	if (block == NULL)
		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 (ret < 0)
		return -ERESTARTSYS;
	req->a_res.status = block->b_status;
	return 0;
}

/*
 * The server lockd has called us back to tell us the lock was granted
 */
__be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
{
	const struct file_lock *fl = &lock->fl;
	const struct nfs_fh *fh = &lock->fh;
	struct nlm_wait	*block;
	__be32 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) {
		struct file_lock *fl_blocked = block->b_lock;

		if (fl_blocked->fl_start != fl->fl_start)
			continue;
		if (fl_blocked->fl_end != fl->fl_end)
			continue;
		/*
		 * Careful! The NLM server will return the 32-bit "pid" that
		 * we put on the wire: in this case the lockowner "pid".
		 */
		if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
			continue;
		if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
			continue;
		if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
			continue;
		/* Alright, we found a lock. Set the return status
		 * and wake up the caller
		 */
		block->b_status = nlm_granted;
		wake_up(&block->b_wait);
		res = nlm_granted;
	}
	return res;
}

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

/*
 * Reclaim all locks on server host. We do this by spawning a separate
 * reclaimer thread.
 */
void
nlmclnt_recovery(struct nlm_host *host)
{
	struct task_struct *task;

	if (!host->h_reclaiming++) {
		nlm_get_host(host);
		task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
		if (IS_ERR(task))
			printk(KERN_ERR "lockd: unable to spawn reclaimer "
				"thread. Locks for %s won't be reclaimed! "
				"(%ld)\n", host->h_name, PTR_ERR(task));
	}
}

static int
reclaimer(void *ptr)
{
	struct nlm_host	  *host = (struct nlm_host *) ptr;
	struct nlm_wait	  *block;
	struct file_lock *fl, *next;
	u32 nsmstate;

	allow_signal(SIGKILL);

	down_write(&host->h_rwsem);

	/* This one ensures that our parent doesn't terminate while the
	 * reclaim is in progress */
	lock_kernel();
	lockd_up();	/* note: this cannot fail as lockd is already running */

	dprintk("lockd: reclaiming locks for host %s\n", host->h_name);

restart:
	nsmstate = host->h_nsmstate;

	/* Force a portmap getport - the peer's lockd will
	 * most likely end up on a different port.
	 */
	host->h_nextrebind = jiffies;
	nlm_rebind_host(host);

	/* First, reclaim all locks that have been granted. */
	list_splice_init(&host->h_granted, &host->h_reclaim);
	list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
		list_del_init(&fl->fl_u.nfs_fl.list);

		/*
		 * sending this thread a SIGKILL will result in any unreclaimed
		 * locks being removed from the h_granted list. This means that
		 * the kernel will not attempt to reclaim them again if a new
		 * reclaimer thread is spawned for this host.
		 */
		if (signalled())
			continue;
		if (nlmclnt_reclaim(host, fl) != 0)
			continue;
		list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
		if (host->h_nsmstate != nsmstate) {
			/* Argh! The server rebooted again! */
			goto restart;
		}
	}

	host->h_reclaiming = 0;
	up_write(&host->h_rwsem);
	dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);

	/* 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();
	return 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>
df94f000	17	#include <linux/kthread.h>
1da177e4 LT	18
	19	#define NLMDBG_FACILITY NLMDBG_CLIENT
	20
	21	/*
	22	* Local function prototypes
	23	*/
	24	static int reclaimer(void *ptr);
	25
	26	/*
	27	* The following functions handle blocking and granting from the
	28	* client perspective.
	29	*/
	30
	31	/*
	32	* This is the representation of a blocked client lock.
	33	*/
	34	struct nlm_wait {
4f15e2b1	35	struct list_head b_list; /* linked list */
1da177e4 LT	36	wait_queue_head_t b_wait; /* where to wait on */
	37	struct nlm_host * b_host;
	38	struct file_lock * b_lock; /* local file lock */
	39	unsigned short b_reclaim; /* got to reclaim lock */
e8c5c045	40	__be32 b_status; /* grant callback status */
1da177e4 LT	41	};
1da177e4 LT	42
4f15e2b1	43	static LIST_HEAD(nlm_blocked);
1da177e4	44
52c4044d CL	45	/**
52c4044d CL	46	* nlmclnt_init - Set up per-NFS mount point lockd data structures
883bb163	47	* @nlm_init: pointer to arguments structure
52c4044d CL	48	*
	49	* Returns pointer to an appropriate nlm_host struct,
	50	* or an ERR_PTR value.
	51	*/
883bb163	52	struct nlm_host nlmclnt_init(const struct nlmclnt_initdata nlm_init)
52c4044d CL	53	{
52c4044d CL	54	struct nlm_host *host;
883bb163	55	u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
52c4044d CL	56	int status;
52c4044d CL	57
26a41409	58	status = lockd_up();
52c4044d CL	59	if (status < 0)
	60	return ERR_PTR(status);
	61
d7d20440	62	host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
883bb163	63	nlm_init->protocol, nlm_version,
0cb2659b	64	nlm_init->hostname, nlm_init->noresvport);
52c4044d CL	65	if (host == NULL) {
	66	lockd_down();
	67	return ERR_PTR(-ENOLCK);
	68	}
	69
	70	return host;
	71	}
	72	EXPORT_SYMBOL_GPL(nlmclnt_init);
	73
	74	/**
	75	* nlmclnt_done - Release resources allocated by nlmclnt_init()
	76	* @host: nlm_host structure reserved by nlmclnt_init()
	77	*
	78	*/
	79	void nlmclnt_done(struct nlm_host *host)
	80	{
	81	nlm_release_host(host);
	82	lockd_down();
	83	}
	84	EXPORT_SYMBOL_GPL(nlmclnt_done);
	85
1da177e4	86	/*
ecdbf769	87	* Queue up a lock for blocking so that the GRANTED request can see it
1da177e4	88	*/
3a649b88	89	struct nlm_wait nlmclnt_prepare_block(struct nlm_host host, struct file_lock *fl)
ecdbf769 TM	90	{
	91	struct nlm_wait *block;
	92
ecdbf769	93	block = kmalloc(sizeof(*block), GFP_KERNEL);
3a649b88 TM	94	if (block != NULL) {
	95	block->b_host = host;
	96	block->b_lock = fl;
	97	init_waitqueue_head(&block->b_wait);
e8c5c045	98	block->b_status = nlm_lck_blocked;
3a649b88 TM	99	list_add(&block->b_list, &nlm_blocked);
	100	}
	101	return block;
ecdbf769 TM	102	}
ecdbf769 TM	103
3a649b88	104	void nlmclnt_finish_block(struct nlm_wait *block)
1da177e4	105	{
ecdbf769 TM	106	if (block == NULL)
ecdbf769 TM	107	return;
ecdbf769 TM	108	list_del(&block->b_list);
	109	kfree(block);
	110	}
1da177e4	111
ecdbf769 TM	112	/*
	113	* Block on a lock
	114	*/
3a649b88	115	int nlmclnt_block(struct nlm_wait block, struct nlm_rqst req, long timeout)
ecdbf769	116	{
ecdbf769	117	long ret;
1da177e4	118
ecdbf769 TM	119	/* A borken server might ask us to block even if we didn't
	120	* request it. Just say no!
	121	*/
3a649b88	122	if (block == NULL)
ecdbf769	123	return -EAGAIN;
1da177e4 LT	124
	125	/* Go to sleep waiting for GRANT callback. Some servers seem
	126	* to lose callbacks, however, so we're going to poll from
	127	* time to time just to make sure.
	128	*
	129	* For now, the retry frequency is pretty high; normally
	130	* a 1 minute timeout would do. See the comment before
	131	* nlmclnt_lock for an explanation.
	132	*/
ecdbf769	133	ret = wait_event_interruptible_timeout(block->b_wait,
e8c5c045	134	block->b_status != nlm_lck_blocked,
ecdbf769	135	timeout);
3a649b88 TM	136	if (ret < 0)
	137	return -ERESTARTSYS;
	138	req->a_res.status = block->b_status;
	139	return 0;
1da177e4 LT	140	}
	141
	142	/*
	143	* The server lockd has called us back to tell us the lock was granted
	144	*/
dcff09f1	145	__be32 nlmclnt_grant(const struct sockaddr addr, const struct nlm_lock lock)
1da177e4	146	{
5ac5f9d1 TM	147	const struct file_lock *fl = &lock->fl;
5ac5f9d1 TM	148	const struct nfs_fh *fh = &lock->fh;
1da177e4	149	struct nlm_wait *block;
52921e02	150	__be32 res = nlm_lck_denied;
1da177e4 LT	151
	152	/*
	153	* Look up blocked request based on arguments.
	154	* Warning: must not use cookie to match it!
	155	*/
4f15e2b1	156	list_for_each_entry(block, &nlm_blocked, b_list) {
5ac5f9d1 TM	157	struct file_lock *fl_blocked = block->b_lock;
5ac5f9d1 TM	158
7bab377f TM	159	if (fl_blocked->fl_start != fl->fl_start)
	160	continue;
	161	if (fl_blocked->fl_end != fl->fl_end)
	162	continue;
	163	/*
	164	* Careful! The NLM server will return the 32-bit "pid" that
	165	* we put on the wire: in this case the lockowner "pid".
	166	*/
	167	if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
5ac5f9d1	168	continue;
4516fc04	169	if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
5ac5f9d1	170	continue;
225a719f	171	if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
5ac5f9d1 TM	172	continue;
	173	/* Alright, we found a lock. Set the return status
	174	* and wake up the caller
	175	*/
e8c5c045	176	block->b_status = nlm_granted;
5ac5f9d1 TM	177	wake_up(&block->b_wait);
5ac5f9d1 TM	178	res = nlm_granted;
1da177e4	179	}
ecdbf769	180	return res;
1da177e4 LT	181	}
	182
	183	/*
	184	* The following procedures deal with the recovery of locks after a
	185	* server crash.
	186	*/
	187
1da177e4 LT	188	/*
	189	* Reclaim all locks on server host. We do this by spawning a separate
	190	* reclaimer thread.
	191	*/
	192	void
5c8dd29c	193	nlmclnt_recovery(struct nlm_host *host)
1da177e4	194	{
df94f000 JL	195	struct task_struct *task;
df94f000 JL	196
28df955a	197	if (!host->h_reclaiming++) {
1da177e4	198	nlm_get_host(host);
df94f000 JL	199	task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
	200	if (IS_ERR(task))
	201	printk(KERN_ERR "lockd: unable to spawn reclaimer "
	202	"thread. Locks for %s won't be reclaimed! "
	203	"(%ld)\n", host->h_name, PTR_ERR(task));
1da177e4 LT	204	}
	205	}
	206
	207	static int
	208	reclaimer(void *ptr)
	209	{
	210	struct nlm_host host = (struct nlm_host ) ptr;
	211	struct nlm_wait *block;
26bcbf96	212	struct file_lock fl, next;
28df955a	213	u32 nsmstate;
1da177e4	214
1da177e4 LT	215	allow_signal(SIGKILL);
1da177e4 LT	216
5c8dd29c OK	217	down_write(&host->h_rwsem);
5c8dd29c OK	218
1da177e4 LT	219	/* This one ensures that our parent doesn't terminate while the
	220	* reclaim is in progress */
	221	lock_kernel();
26a41409	222	lockd_up(); /* note: this cannot fail as lockd is already running */
1da177e4	223
d019bcf0	224	dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
5c8dd29c	225
1da177e4	226	restart:
28df955a	227	nsmstate = host->h_nsmstate;
5c8dd29c OK	228
	229	/* Force a portmap getport - the peer's lockd will
	230	* most likely end up on a different port.
	231	*/
0ade060e	232	host->h_nextrebind = jiffies;
5c8dd29c OK	233	nlm_rebind_host(host);
	234
	235	/* First, reclaim all locks that have been granted. */
	236	list_splice_init(&host->h_granted, &host->h_reclaim);
26bcbf96	237	list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
4c060b53	238	list_del_init(&fl->fl_u.nfs_fl.list);
1da177e4	239
df94f000 JL	240	/*
	241	* sending this thread a SIGKILL will result in any unreclaimed
	242	* locks being removed from the h_granted list. This means that
	243	* the kernel will not attempt to reclaim them again if a new
	244	* reclaimer thread is spawned for this host.
	245	*/
1da177e4	246	if (signalled())
4c060b53	247	continue;
28df955a TM	248	if (nlmclnt_reclaim(host, fl) != 0)
	249	continue;
	250	list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
	251	if (host->h_nsmstate != nsmstate) {
	252	/* Argh! The server rebooted again! */
28df955a TM	253	goto restart;
28df955a TM	254	}
1da177e4	255	}
5c8dd29c OK	256
	257	host->h_reclaiming = 0;
	258	up_write(&host->h_rwsem);
d019bcf0	259	dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
1da177e4 LT	260
1da177e4 LT	261	/* Now, wake up all processes that sleep on a blocked lock */
4f15e2b1	262	list_for_each_entry(block, &nlm_blocked, b_list) {
1da177e4	263	if (block->b_host == host) {
e8c5c045	264	block->b_status = nlm_lck_denied_grace_period;
1da177e4 LT	265	wake_up(&block->b_wait);
	266	}
	267	}
	268
	269	/* Release host handle after use */
	270	nlm_release_host(host);
	271	lockd_down();
	272	unlock_kernel();
df94f000	273	return 0;
1da177e4	274	}