[mirror_ubuntu-artful-kernel.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/slab.h>
#include <linux/time.h>
#include <linux/nfs_fs.h>
#include <linux/sunrpc/addr.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.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);
static DEFINE_SPINLOCK(nlm_blocked_lock);

/**
 * 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(nlm_init->net);
	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,
				   nlm_init->net);
	if (host == NULL)
		goto out_nohost;
	if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
		goto out_nobind;

	host->h_nlmclnt_ops = nlm_init->nlmclnt_ops;
	return host;
out_nobind:
	nlmclnt_release_host(host);
out_nohost:
	lockd_down(nlm_init->net);
	return ERR_PTR(-ENOLCK);
}
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)
{
	struct net *net = host->net;

	nlmclnt_release_host(host);
	lockd_down(net);
}
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;

		spin_lock(&nlm_blocked_lock);
		list_add(&block->b_list, &nlm_blocked);
		spin_unlock(&nlm_blocked_lock);
	}
	return block;
}

void nlmclnt_finish_block(struct nlm_wait *block)
{
	if (block == NULL)
		return;
	spin_lock(&nlm_blocked_lock);
	list_del(&block->b_list);
	spin_unlock(&nlm_blocked_lock);
	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;
	/* Reset the lock status after a server reboot so we resend */
	if (block->b_status == nlm_lck_denied_grace_period)
		block->b_status = nlm_lck_blocked;
	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!
	 */
	spin_lock(&nlm_blocked_lock);
	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(file_inode(fl_blocked->fl_file)) ,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;
	}
	spin_unlock(&nlm_blocked_lock);
	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 nlm_rqst   *req;
	struct file_lock *fl, *next;
	u32 nsmstate;
	struct net *net = host->net;

	req = kmalloc(sizeof(*req), GFP_KERNEL);
	if (!req) {
		printk(KERN_ERR "lockd: reclaimer unable to alloc memory."
				" Locks for %s won't be reclaimed!\n",
				host->h_name);
		return 0;
	}

	allow_signal(SIGKILL);

	down_write(&host->h_rwsem);
	lockd_up(net);	/* 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, req) != 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 */
	spin_lock(&nlm_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);
		}
	}
	spin_unlock(&nlm_blocked_lock);

	/* Release host handle after use */
	nlmclnt_release_host(host);
	lockd_down(net);
	kfree(req);
	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>
5a0e3ad6	11	#include <linux/slab.h>
1da177e4 LT	12	#include <linux/time.h>
1da177e4 LT	13	#include <linux/nfs_fs.h>
5976687a	14	#include <linux/sunrpc/addr.h>
1da177e4 LT	15	#include <linux/sunrpc/svc.h>
1da177e4 LT	16	#include <linux/lockd/lockd.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);
63185942	44	static DEFINE_SPINLOCK(nlm_blocked_lock);
1da177e4	45
52c4044d CL	46	/**
52c4044d CL	47	* nlmclnt_init - Set up per-NFS mount point lockd data structures
883bb163	48	* @nlm_init: pointer to arguments structure
52c4044d CL	49	*
	50	* Returns pointer to an appropriate nlm_host struct,
	51	* or an ERR_PTR value.
	52	*/
883bb163	53	struct nlm_host nlmclnt_init(const struct nlmclnt_initdata nlm_init)
52c4044d CL	54	{
52c4044d CL	55	struct nlm_host *host;
883bb163	56	u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
52c4044d CL	57	int status;
52c4044d CL	58
e3f70ead	59	status = lockd_up(nlm_init->net);
52c4044d CL	60	if (status < 0)
	61	return ERR_PTR(status);
	62
d7d20440	63	host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
883bb163	64	nlm_init->protocol, nlm_version,
66697bfd SK	65	nlm_init->hostname, nlm_init->noresvport,
66697bfd SK	66	nlm_init->net);
9a1b6bf8 TM	67	if (host == NULL)
	68	goto out_nohost;
	69	if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
	70	goto out_nobind;
52c4044d	71
b1ece737	72	host->h_nlmclnt_ops = nlm_init->nlmclnt_ops;
52c4044d	73	return host;
9a1b6bf8 TM	74	out_nobind:
	75	nlmclnt_release_host(host);
	76	out_nohost:
	77	lockd_down(nlm_init->net);
	78	return ERR_PTR(-ENOLCK);
52c4044d CL	79	}
	80	EXPORT_SYMBOL_GPL(nlmclnt_init);
	81
	82	/**
	83	* nlmclnt_done - Release resources allocated by nlmclnt_init()
	84	* @host: nlm_host structure reserved by nlmclnt_init()
	85	*
	86	*/
	87	void nlmclnt_done(struct nlm_host *host)
	88	{
e3f70ead SK	89	struct net *net = host->net;
e3f70ead SK	90
8ea6ecc8	91	nlmclnt_release_host(host);
e3f70ead	92	lockd_down(net);
52c4044d CL	93	}
	94	EXPORT_SYMBOL_GPL(nlmclnt_done);
	95
1da177e4	96	/*
ecdbf769	97	* Queue up a lock for blocking so that the GRANTED request can see it
1da177e4	98	*/
3a649b88	99	struct nlm_wait nlmclnt_prepare_block(struct nlm_host host, struct file_lock *fl)
ecdbf769 TM	100	{
	101	struct nlm_wait *block;
	102
ecdbf769	103	block = kmalloc(sizeof(*block), GFP_KERNEL);
3a649b88 TM	104	if (block != NULL) {
	105	block->b_host = host;
	106	block->b_lock = fl;
	107	init_waitqueue_head(&block->b_wait);
e8c5c045	108	block->b_status = nlm_lck_blocked;
63185942 BS	109
63185942 BS	110	spin_lock(&nlm_blocked_lock);
3a649b88	111	list_add(&block->b_list, &nlm_blocked);
63185942	112	spin_unlock(&nlm_blocked_lock);
3a649b88 TM	113	}
3a649b88 TM	114	return block;
ecdbf769 TM	115	}
ecdbf769 TM	116
3a649b88	117	void nlmclnt_finish_block(struct nlm_wait *block)
1da177e4	118	{
ecdbf769 TM	119	if (block == NULL)
ecdbf769 TM	120	return;
63185942	121	spin_lock(&nlm_blocked_lock);
ecdbf769	122	list_del(&block->b_list);
63185942	123	spin_unlock(&nlm_blocked_lock);
ecdbf769 TM	124	kfree(block);
ecdbf769 TM	125	}
1da177e4	126
ecdbf769 TM	127	/*
	128	* Block on a lock
	129	*/
3a649b88	130	int nlmclnt_block(struct nlm_wait block, struct nlm_rqst req, long timeout)
ecdbf769	131	{
ecdbf769	132	long ret;
1da177e4	133
ecdbf769 TM	134	/* A borken server might ask us to block even if we didn't
	135	* request it. Just say no!
	136	*/
3a649b88	137	if (block == NULL)
ecdbf769	138	return -EAGAIN;
1da177e4 LT	139
	140	/* Go to sleep waiting for GRANT callback. Some servers seem
	141	* to lose callbacks, however, so we're going to poll from
	142	* time to time just to make sure.
	143	*
	144	* For now, the retry frequency is pretty high; normally
	145	* a 1 minute timeout would do. See the comment before
	146	* nlmclnt_lock for an explanation.
	147	*/
ecdbf769	148	ret = wait_event_interruptible_timeout(block->b_wait,
e8c5c045	149	block->b_status != nlm_lck_blocked,
ecdbf769	150	timeout);
3a649b88 TM	151	if (ret < 0)
3a649b88 TM	152	return -ERESTARTSYS;
1dfd89af TM	153	/* Reset the lock status after a server reboot so we resend */
	154	if (block->b_status == nlm_lck_denied_grace_period)
	155	block->b_status = nlm_lck_blocked;
3a649b88 TM	156	req->a_res.status = block->b_status;
3a649b88 TM	157	return 0;
1da177e4 LT	158	}
	159
	160	/*
	161	* The server lockd has called us back to tell us the lock was granted
	162	*/
dcff09f1	163	__be32 nlmclnt_grant(const struct sockaddr addr, const struct nlm_lock lock)
1da177e4	164	{
5ac5f9d1 TM	165	const struct file_lock *fl = &lock->fl;
5ac5f9d1 TM	166	const struct nfs_fh *fh = &lock->fh;
1da177e4	167	struct nlm_wait *block;
52921e02	168	__be32 res = nlm_lck_denied;
1da177e4 LT	169
	170	/*
	171	* Look up blocked request based on arguments.
	172	* Warning: must not use cookie to match it!
	173	*/
63185942	174	spin_lock(&nlm_blocked_lock);
4f15e2b1	175	list_for_each_entry(block, &nlm_blocked, b_list) {
5ac5f9d1 TM	176	struct file_lock *fl_blocked = block->b_lock;
5ac5f9d1 TM	177
7bab377f TM	178	if (fl_blocked->fl_start != fl->fl_start)
	179	continue;
	180	if (fl_blocked->fl_end != fl->fl_end)
	181	continue;
	182	/*
	183	* Careful! The NLM server will return the 32-bit "pid" that
	184	* we put on the wire: in this case the lockowner "pid".
	185	*/
	186	if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
5ac5f9d1	187	continue;
4516fc04	188	if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
5ac5f9d1	189	continue;
496ad9aa	190	if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)) ,fh) != 0)
5ac5f9d1 TM	191	continue;
	192	/* Alright, we found a lock. Set the return status
	193	* and wake up the caller
	194	*/
e8c5c045	195	block->b_status = nlm_granted;
5ac5f9d1 TM	196	wake_up(&block->b_wait);
5ac5f9d1 TM	197	res = nlm_granted;
1da177e4	198	}
63185942	199	spin_unlock(&nlm_blocked_lock);
ecdbf769	200	return res;
1da177e4 LT	201	}
	202
	203	/*
	204	* The following procedures deal with the recovery of locks after a
	205	* server crash.
	206	*/
	207
1da177e4 LT	208	/*
	209	* Reclaim all locks on server host. We do this by spawning a separate
	210	* reclaimer thread.
	211	*/
	212	void
5c8dd29c	213	nlmclnt_recovery(struct nlm_host *host)
1da177e4	214	{
df94f000 JL	215	struct task_struct *task;
df94f000 JL	216
28df955a	217	if (!host->h_reclaiming++) {
1da177e4	218	nlm_get_host(host);
df94f000 JL	219	task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
	220	if (IS_ERR(task))
	221	printk(KERN_ERR "lockd: unable to spawn reclaimer "
	222	"thread. Locks for %s won't be reclaimed! "
	223	"(%ld)\n", host->h_name, PTR_ERR(task));
1da177e4 LT	224	}
	225	}
	226
	227	static int
	228	reclaimer(void *ptr)
	229	{
	230	struct nlm_host host = (struct nlm_host ) ptr;
	231	struct nlm_wait *block;
f25cc71e	232	struct nlm_rqst *req;
26bcbf96	233	struct file_lock fl, next;
28df955a	234	u32 nsmstate;
e3f70ead	235	struct net *net = host->net;
1da177e4	236
f25cc71e TG	237	req = kmalloc(sizeof(*req), GFP_KERNEL);
	238	if (!req) {
	239	printk(KERN_ERR "lockd: reclaimer unable to alloc memory."
	240	" Locks for %s won't be reclaimed!\n",
	241	host->h_name);
	242	return 0;
	243	}
	244
1da177e4 LT	245	allow_signal(SIGKILL);
1da177e4 LT	246
5c8dd29c	247	down_write(&host->h_rwsem);
e3f70ead	248	lockd_up(net); /* note: this cannot fail as lockd is already running */
1da177e4	249
d019bcf0	250	dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
5c8dd29c	251
1da177e4	252	restart:
28df955a	253	nsmstate = host->h_nsmstate;
5c8dd29c OK	254
	255	/* Force a portmap getport - the peer's lockd will
	256	* most likely end up on a different port.
	257	*/
0ade060e	258	host->h_nextrebind = jiffies;
5c8dd29c OK	259	nlm_rebind_host(host);
	260
	261	/* First, reclaim all locks that have been granted. */
	262	list_splice_init(&host->h_granted, &host->h_reclaim);
26bcbf96	263	list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
4c060b53	264	list_del_init(&fl->fl_u.nfs_fl.list);
1da177e4	265
df94f000 JL	266	/*
	267	* sending this thread a SIGKILL will result in any unreclaimed
	268	* locks being removed from the h_granted list. This means that
	269	* the kernel will not attempt to reclaim them again if a new
	270	* reclaimer thread is spawned for this host.
	271	*/
1da177e4	272	if (signalled())
4c060b53	273	continue;
f25cc71e	274	if (nlmclnt_reclaim(host, fl, req) != 0)
28df955a TM	275	continue;
	276	list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
	277	if (host->h_nsmstate != nsmstate) {
	278	/* Argh! The server rebooted again! */
28df955a TM	279	goto restart;
28df955a TM	280	}
1da177e4	281	}
5c8dd29c OK	282
	283	host->h_reclaiming = 0;
	284	up_write(&host->h_rwsem);
d019bcf0	285	dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
1da177e4 LT	286
1da177e4 LT	287	/* Now, wake up all processes that sleep on a blocked lock */
63185942	288	spin_lock(&nlm_blocked_lock);
4f15e2b1	289	list_for_each_entry(block, &nlm_blocked, b_list) {
1da177e4	290	if (block->b_host == host) {
e8c5c045	291	block->b_status = nlm_lck_denied_grace_period;
1da177e4 LT	292	wake_up(&block->b_wait);
	293	}
	294	}
63185942	295	spin_unlock(&nlm_blocked_lock);
1da177e4 LT	296
1da177e4 LT	297	/* Release host handle after use */
8ea6ecc8	298	nlmclnt_release_host(host);
e3f70ead	299	lockd_down(net);
f25cc71e	300	kfree(req);
df94f000	301	return 0;
1da177e4	302	}