[deliverable/linux.git] / fs / nfs / delegation.c

/*
 * linux/fs/nfs/delegation.c
 *
 * Copyright (C) 2004 Trond Myklebust
 *
 * NFS file delegation management
 *
 */
#include <linux/config.h>
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/spinlock.h>

#include <linux/nfs4.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_xdr.h>

#include "nfs4_fs.h"
#include "delegation.h"

static struct nfs_delegation *nfs_alloc_delegation(void)
{
	return (struct nfs_delegation *)kmalloc(sizeof(struct nfs_delegation), GFP_KERNEL);
}

static void nfs_free_delegation(struct nfs_delegation *delegation)
{
	if (delegation->cred)
		put_rpccred(delegation->cred);
	kfree(delegation);
}

static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state)
{
	struct inode *inode = state->inode;
	struct file_lock *fl;
	int status;

	for (fl = inode->i_flock; fl != 0; fl = fl->fl_next) {
		if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
			continue;
		if ((struct nfs_open_context *)fl->fl_file->private_data != ctx)
			continue;
		status = nfs4_lock_delegation_recall(state, fl);
		if (status >= 0)
			continue;
		switch (status) {
			default:
				printk(KERN_ERR "%s: unhandled error %d.\n",
						__FUNCTION__, status);
			case -NFS4ERR_EXPIRED:
				/* kill_proc(fl->fl_pid, SIGLOST, 1); */
			case -NFS4ERR_STALE_CLIENTID:
				nfs4_schedule_state_recovery(NFS_SERVER(inode)->nfs4_state);
				goto out_err;
		}
	}
	return 0;
out_err:
	return status;
}

static void nfs_delegation_claim_opens(struct inode *inode)
{
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_open_context *ctx;
	struct nfs4_state *state;
	int err;

again:
	spin_lock(&inode->i_lock);
	list_for_each_entry(ctx, &nfsi->open_files, list) {
		state = ctx->state;
		if (state == NULL)
			continue;
		if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
			continue;
		get_nfs_open_context(ctx);
		spin_unlock(&inode->i_lock);
		err = nfs4_open_delegation_recall(ctx->dentry, state);
		if (err >= 0)
			err = nfs_delegation_claim_locks(ctx, state);
		put_nfs_open_context(ctx);
		if (err != 0)
			return;
		goto again;
	}
	spin_unlock(&inode->i_lock);
}

/*
 * Set up a delegation on an inode
 */
void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
{
	struct nfs_delegation *delegation = NFS_I(inode)->delegation;

	if (delegation == NULL)
		return;
	memcpy(delegation->stateid.data, res->delegation.data,
			sizeof(delegation->stateid.data));
	delegation->type = res->delegation_type;
	delegation->maxsize = res->maxsize;
	put_rpccred(cred);
	delegation->cred = get_rpccred(cred);
	delegation->flags &= ~NFS_DELEGATION_NEED_RECLAIM;
	NFS_I(inode)->delegation_state = delegation->type;
	smp_wmb();
}

/*
 * Set up a delegation on an inode
 */
int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
{
	struct nfs4_client *clp = NFS_SERVER(inode)->nfs4_state;
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;
	int status = 0;

	/* Ensure we first revalidate the attributes and page cache! */
	if ((nfsi->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_ATTR)))
		__nfs_revalidate_inode(NFS_SERVER(inode), inode);

	delegation = nfs_alloc_delegation();
	if (delegation == NULL)
		return -ENOMEM;
	memcpy(delegation->stateid.data, res->delegation.data,
			sizeof(delegation->stateid.data));
	delegation->type = res->delegation_type;
	delegation->maxsize = res->maxsize;
	delegation->change_attr = nfsi->change_attr;
	delegation->cred = get_rpccred(cred);
	delegation->inode = inode;

	spin_lock(&clp->cl_lock);
	if (nfsi->delegation == NULL) {
		list_add(&delegation->super_list, &clp->cl_delegations);
		nfsi->delegation = delegation;
		nfsi->delegation_state = delegation->type;
		delegation = NULL;
	} else {
		if (memcmp(&delegation->stateid, &nfsi->delegation->stateid,
					sizeof(delegation->stateid)) != 0 ||
				delegation->type != nfsi->delegation->type) {
			printk("%s: server %u.%u.%u.%u, handed out a duplicate delegation!\n",
					__FUNCTION__, NIPQUAD(clp->cl_addr));
			status = -EIO;
		}
	}
	spin_unlock(&clp->cl_lock);
	kfree(delegation);
	return status;
}

static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation)
{
	int res = 0;

	__nfs_revalidate_inode(NFS_SERVER(inode), inode);

	res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid);
	nfs_free_delegation(delegation);
	return res;
}

/* Sync all data to disk upon delegation return */
static void nfs_msync_inode(struct inode *inode)
{
	filemap_fdatawrite(inode->i_mapping);
	nfs_wb_all(inode);
	filemap_fdatawait(inode->i_mapping);
}

/*
 * Basic procedure for returning a delegation to the server
 */
int __nfs_inode_return_delegation(struct inode *inode)
{
	struct nfs4_client *clp = NFS_SERVER(inode)->nfs4_state;
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;
	int res = 0;

	nfs_msync_inode(inode);
	down_read(&clp->cl_sem);
	/* Guard against new delegated open calls */
	down_write(&nfsi->rwsem);
	spin_lock(&clp->cl_lock);
	delegation = nfsi->delegation;
	if (delegation != NULL) {
		list_del_init(&delegation->super_list);
		nfsi->delegation = NULL;
		nfsi->delegation_state = 0;
	}
	spin_unlock(&clp->cl_lock);
	nfs_delegation_claim_opens(inode);
	up_write(&nfsi->rwsem);
	up_read(&clp->cl_sem);
	nfs_msync_inode(inode);

	if (delegation != NULL)
		res = nfs_do_return_delegation(inode, delegation);
	return res;
}

/*
 * Return all delegations associated to a super block
 */
void nfs_return_all_delegations(struct super_block *sb)
{
	struct nfs4_client *clp = NFS_SB(sb)->nfs4_state;
	struct nfs_delegation *delegation;
	struct inode *inode;

	if (clp == NULL)
		return;
restart:
	spin_lock(&clp->cl_lock);
	list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
		if (delegation->inode->i_sb != sb)
			continue;
		inode = igrab(delegation->inode);
		if (inode == NULL)
			continue;
		spin_unlock(&clp->cl_lock);
		nfs_inode_return_delegation(inode);
		iput(inode);
		goto restart;
	}
	spin_unlock(&clp->cl_lock);
}

int nfs_do_expire_all_delegations(void *ptr)
{
	struct nfs4_client *clp = ptr;
	struct nfs_delegation *delegation;
	struct inode *inode;
	int err = 0;

	allow_signal(SIGKILL);
restart:
	spin_lock(&clp->cl_lock);
	if (test_bit(NFS4CLNT_STATE_RECOVER, &clp->cl_state) != 0)
		goto out;
	if (test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) == 0)
		goto out;
	list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
		inode = igrab(delegation->inode);
		if (inode == NULL)
			continue;
		spin_unlock(&clp->cl_lock);
		err = nfs_inode_return_delegation(inode);
		iput(inode);
		if (!err)
			goto restart;
	}
out:
	spin_unlock(&clp->cl_lock);
	nfs4_put_client(clp);
	module_put_and_exit(0);
}

void nfs_expire_all_delegations(struct nfs4_client *clp)
{
	struct task_struct *task;

	__module_get(THIS_MODULE);
	atomic_inc(&clp->cl_count);
	task = kthread_run(nfs_do_expire_all_delegations, clp,
			"%u.%u.%u.%u-delegreturn",
			NIPQUAD(clp->cl_addr));
	if (!IS_ERR(task))
		return;
	nfs4_put_client(clp);
	module_put(THIS_MODULE);
}

/*
 * Return all delegations following an NFS4ERR_CB_PATH_DOWN error.
 */
void nfs_handle_cb_pathdown(struct nfs4_client *clp)
{
	struct nfs_delegation *delegation;
	struct inode *inode;

	if (clp == NULL)
		return;
restart:
	spin_lock(&clp->cl_lock);
	list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
		inode = igrab(delegation->inode);
		if (inode == NULL)
			continue;
		spin_unlock(&clp->cl_lock);
		nfs_inode_return_delegation(inode);
		iput(inode);
		goto restart;
	}
	spin_unlock(&clp->cl_lock);
}

struct recall_threadargs {
	struct inode *inode;
	struct nfs4_client *clp;
	const nfs4_stateid *stateid;

	struct completion started;
	int result;
};

static int recall_thread(void *data)
{
	struct recall_threadargs *args = (struct recall_threadargs *)data;
	struct inode *inode = igrab(args->inode);
	struct nfs4_client *clp = NFS_SERVER(inode)->nfs4_state;
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;

	daemonize("nfsv4-delegreturn");

	nfs_msync_inode(inode);
	down_read(&clp->cl_sem);
	down_write(&nfsi->rwsem);
	spin_lock(&clp->cl_lock);
	delegation = nfsi->delegation;
	if (delegation != NULL && memcmp(delegation->stateid.data,
				args->stateid->data,
				sizeof(delegation->stateid.data)) == 0) {
		list_del_init(&delegation->super_list);
		nfsi->delegation = NULL;
		nfsi->delegation_state = 0;
		args->result = 0;
	} else {
		delegation = NULL;
		args->result = -ENOENT;
	}
	spin_unlock(&clp->cl_lock);
	complete(&args->started);
	nfs_delegation_claim_opens(inode);
	up_write(&nfsi->rwsem);
	up_read(&clp->cl_sem);
	nfs_msync_inode(inode);

	if (delegation != NULL)
		nfs_do_return_delegation(inode, delegation);
	iput(inode);
	module_put_and_exit(0);
}

/*
 * Asynchronous delegation recall!
 */
int nfs_async_inode_return_delegation(struct inode *inode, const nfs4_stateid *stateid)
{
	struct recall_threadargs data = {
		.inode = inode,
		.stateid = stateid,
	};
	int status;

	init_completion(&data.started);
	__module_get(THIS_MODULE);
	status = kernel_thread(recall_thread, &data, CLONE_KERNEL);
	if (status < 0)
		goto out_module_put;
	wait_for_completion(&data.started);
	return data.result;
out_module_put:
	module_put(THIS_MODULE);
	return status;
}

/*
 * Retrieve the inode associated with a delegation
 */
struct inode *nfs_delegation_find_inode(struct nfs4_client *clp, const struct nfs_fh *fhandle)
{
	struct nfs_delegation *delegation;
	struct inode *res = NULL;
	spin_lock(&clp->cl_lock);
	list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
		if (nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
			res = igrab(delegation->inode);
			break;
		}
	}
	spin_unlock(&clp->cl_lock);
	return res;
}

/*
 * Mark all delegations as needing to be reclaimed
 */
void nfs_delegation_mark_reclaim(struct nfs4_client *clp)
{
	struct nfs_delegation *delegation;
	spin_lock(&clp->cl_lock);
	list_for_each_entry(delegation, &clp->cl_delegations, super_list)
		delegation->flags |= NFS_DELEGATION_NEED_RECLAIM;
	spin_unlock(&clp->cl_lock);
}

/*
 * Reap all unclaimed delegations after reboot recovery is done
 */
void nfs_delegation_reap_unclaimed(struct nfs4_client *clp)
{
	struct nfs_delegation *delegation, *n;
	LIST_HEAD(head);
	spin_lock(&clp->cl_lock);
	list_for_each_entry_safe(delegation, n, &clp->cl_delegations, super_list) {
		if ((delegation->flags & NFS_DELEGATION_NEED_RECLAIM) == 0)
			continue;
		list_move(&delegation->super_list, &head);
		NFS_I(delegation->inode)->delegation = NULL;
		NFS_I(delegation->inode)->delegation_state = 0;
	}
	spin_unlock(&clp->cl_lock);
	while(!list_empty(&head)) {
		delegation = list_entry(head.next, struct nfs_delegation, super_list);
		list_del(&delegation->super_list);
		nfs_free_delegation(delegation);
	}
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/fs/nfs/delegation.c
	3	*
	4	* Copyright (C) 2004 Trond Myklebust
	5	*
	6	* NFS file delegation management
	7	*
	8	*/
	9	#include <linux/config.h>
	10	#include <linux/completion.h>
58d9714a	11	#include <linux/kthread.h>
1da177e4 LT	12	#include <linux/module.h>
	13	#include <linux/sched.h>
	14	#include <linux/spinlock.h>
	15
	16	#include <linux/nfs4.h>
	17	#include <linux/nfs_fs.h>
	18	#include <linux/nfs_xdr.h>
	19
4ce79717	20	#include "nfs4_fs.h"
1da177e4 LT	21	#include "delegation.h"
	22
	23	static struct nfs_delegation *nfs_alloc_delegation(void)
	24	{
	25	return (struct nfs_delegation *)kmalloc(sizeof(struct nfs_delegation), GFP_KERNEL);
	26	}
	27
	28	static void nfs_free_delegation(struct nfs_delegation *delegation)
	29	{
	30	if (delegation->cred)
	31	put_rpccred(delegation->cred);
	32	kfree(delegation);
	33	}
	34
888e694c TM	35	static int nfs_delegation_claim_locks(struct nfs_open_context ctx, struct nfs4_state state)
	36	{
	37	struct inode *inode = state->inode;
	38	struct file_lock *fl;
	39	int status;
	40
	41	for (fl = inode->i_flock; fl != 0; fl = fl->fl_next) {
	42	if (!(fl->fl_flags & (FL_POSIX\|FL_FLOCK)))
	43	continue;
	44	if ((struct nfs_open_context *)fl->fl_file->private_data != ctx)
	45	continue;
	46	status = nfs4_lock_delegation_recall(state, fl);
	47	if (status >= 0)
	48	continue;
	49	switch (status) {
	50	default:
	51	printk(KERN_ERR "%s: unhandled error %d.\n",
	52	__FUNCTION__, status);
	53	case -NFS4ERR_EXPIRED:
	54	/* kill_proc(fl->fl_pid, SIGLOST, 1); */
	55	case -NFS4ERR_STALE_CLIENTID:
	56	nfs4_schedule_state_recovery(NFS_SERVER(inode)->nfs4_state);
	57	goto out_err;
	58	}
	59	}
	60	return 0;
	61	out_err:
	62	return status;
	63	}
	64
1da177e4 LT	65	static void nfs_delegation_claim_opens(struct inode *inode)
	66	{
	67	struct nfs_inode *nfsi = NFS_I(inode);
	68	struct nfs_open_context *ctx;
	69	struct nfs4_state *state;
888e694c	70	int err;
1da177e4 LT	71
	72	again:
	73	spin_lock(&inode->i_lock);
	74	list_for_each_entry(ctx, &nfsi->open_files, list) {
	75	state = ctx->state;
	76	if (state == NULL)
	77	continue;
	78	if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
	79	continue;
	80	get_nfs_open_context(ctx);
	81	spin_unlock(&inode->i_lock);
888e694c TM	82	err = nfs4_open_delegation_recall(ctx->dentry, state);
	83	if (err >= 0)
	84	err = nfs_delegation_claim_locks(ctx, state);
1da177e4	85	put_nfs_open_context(ctx);
888e694c TM	86	if (err != 0)
888e694c TM	87	return;
1da177e4 LT	88	goto again;
	89	}
	90	spin_unlock(&inode->i_lock);
	91	}
	92
	93	/*
	94	* Set up a delegation on an inode
	95	*/
	96	void nfs_inode_reclaim_delegation(struct inode inode, struct rpc_cred cred, struct nfs_openres *res)
	97	{
	98	struct nfs_delegation *delegation = NFS_I(inode)->delegation;
	99
	100	if (delegation == NULL)
	101	return;
	102	memcpy(delegation->stateid.data, res->delegation.data,
	103	sizeof(delegation->stateid.data));
	104	delegation->type = res->delegation_type;
	105	delegation->maxsize = res->maxsize;
	106	put_rpccred(cred);
	107	delegation->cred = get_rpccred(cred);
	108	delegation->flags &= ~NFS_DELEGATION_NEED_RECLAIM;
	109	NFS_I(inode)->delegation_state = delegation->type;
	110	smp_wmb();
	111	}
	112
	113	/*
	114	* Set up a delegation on an inode
	115	*/
	116	int nfs_inode_set_delegation(struct inode inode, struct rpc_cred cred, struct nfs_openres *res)
	117	{
	118	struct nfs4_client *clp = NFS_SERVER(inode)->nfs4_state;
	119	struct nfs_inode *nfsi = NFS_I(inode);
	120	struct nfs_delegation *delegation;
	121	int status = 0;
	122
b3c52da3 TM	123	/* Ensure we first revalidate the attributes and page cache! */
	124	if ((nfsi->cache_validity & (NFS_INO_REVAL_PAGECACHE\|NFS_INO_INVALID_ATTR)))
	125	__nfs_revalidate_inode(NFS_SERVER(inode), inode);
	126
1da177e4 LT	127	delegation = nfs_alloc_delegation();
	128	if (delegation == NULL)
	129	return -ENOMEM;
	130	memcpy(delegation->stateid.data, res->delegation.data,
	131	sizeof(delegation->stateid.data));
	132	delegation->type = res->delegation_type;
	133	delegation->maxsize = res->maxsize;
beb2a5ec	134	delegation->change_attr = nfsi->change_attr;
1da177e4 LT	135	delegation->cred = get_rpccred(cred);
	136	delegation->inode = inode;
	137
	138	spin_lock(&clp->cl_lock);
	139	if (nfsi->delegation == NULL) {
	140	list_add(&delegation->super_list, &clp->cl_delegations);
	141	nfsi->delegation = delegation;
	142	nfsi->delegation_state = delegation->type;
	143	delegation = NULL;
	144	} else {
	145	if (memcmp(&delegation->stateid, &nfsi->delegation->stateid,
	146	sizeof(delegation->stateid)) != 0 \|\|
	147	delegation->type != nfsi->delegation->type) {
	148	printk("%s: server %u.%u.%u.%u, handed out a duplicate delegation!\n",
	149	__FUNCTION__, NIPQUAD(clp->cl_addr));
	150	status = -EIO;
	151	}
	152	}
	153	spin_unlock(&clp->cl_lock);
f99d49ad	154	kfree(delegation);
1da177e4 LT	155	return status;
	156	}
	157
	158	static int nfs_do_return_delegation(struct inode inode, struct nfs_delegation delegation)
	159	{
	160	int res = 0;
	161
	162	__nfs_revalidate_inode(NFS_SERVER(inode), inode);
	163
	164	res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid);
	165	nfs_free_delegation(delegation);
	166	return res;
	167	}
	168
	169	/* Sync all data to disk upon delegation return */
	170	static void nfs_msync_inode(struct inode *inode)
	171	{
	172	filemap_fdatawrite(inode->i_mapping);
	173	nfs_wb_all(inode);
	174	filemap_fdatawait(inode->i_mapping);
	175	}
	176
	177	/*
	178	* Basic procedure for returning a delegation to the server
	179	*/
cae7a073	180	int __nfs_inode_return_delegation(struct inode *inode)
1da177e4 LT	181	{
	182	struct nfs4_client *clp = NFS_SERVER(inode)->nfs4_state;
	183	struct nfs_inode *nfsi = NFS_I(inode);
	184	struct nfs_delegation *delegation;
	185	int res = 0;
	186
	187	nfs_msync_inode(inode);
	188	down_read(&clp->cl_sem);
	189	/* Guard against new delegated open calls */
	190	down_write(&nfsi->rwsem);
	191	spin_lock(&clp->cl_lock);
	192	delegation = nfsi->delegation;
	193	if (delegation != NULL) {
	194	list_del_init(&delegation->super_list);
	195	nfsi->delegation = NULL;
	196	nfsi->delegation_state = 0;
	197	}
	198	spin_unlock(&clp->cl_lock);
	199	nfs_delegation_claim_opens(inode);
	200	up_write(&nfsi->rwsem);
	201	up_read(&clp->cl_sem);
	202	nfs_msync_inode(inode);
	203
	204	if (delegation != NULL)
	205	res = nfs_do_return_delegation(inode, delegation);
	206	return res;
	207	}
	208
	209	/*
	210	* Return all delegations associated to a super block
	211	*/
	212	void nfs_return_all_delegations(struct super_block *sb)
	213	{
	214	struct nfs4_client *clp = NFS_SB(sb)->nfs4_state;
	215	struct nfs_delegation *delegation;
	216	struct inode *inode;
	217
	218	if (clp == NULL)
	219	return;
	220	restart:
	221	spin_lock(&clp->cl_lock);
	222	list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
	223	if (delegation->inode->i_sb != sb)
	224	continue;
	225	inode = igrab(delegation->inode);
	226	if (inode == NULL)
	227	continue;
	228	spin_unlock(&clp->cl_lock);
	229	nfs_inode_return_delegation(inode);
	230	iput(inode);
	231	goto restart;
	232	}
	233	spin_unlock(&clp->cl_lock);
	234	}
	235
58d9714a TM	236	int nfs_do_expire_all_delegations(void *ptr)
	237	{
	238	struct nfs4_client *clp = ptr;
	239	struct nfs_delegation *delegation;
	240	struct inode *inode;
	241	int err = 0;
	242
	243	allow_signal(SIGKILL);
	244	restart:
	245	spin_lock(&clp->cl_lock);
	246	if (test_bit(NFS4CLNT_STATE_RECOVER, &clp->cl_state) != 0)
	247	goto out;
	248	if (test_bit(NFS4CLNT_LEASE_EXPIRED, &clp->cl_state) == 0)
	249	goto out;
	250	list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
	251	inode = igrab(delegation->inode);
	252	if (inode == NULL)
	253	continue;
	254	spin_unlock(&clp->cl_lock);
	255	err = nfs_inode_return_delegation(inode);
	256	iput(inode);
	257	if (!err)
	258	goto restart;
	259	}
	260	out:
	261	spin_unlock(&clp->cl_lock);
	262	nfs4_put_client(clp);
	263	module_put_and_exit(0);
	264	}
	265
	266	void nfs_expire_all_delegations(struct nfs4_client *clp)
	267	{
	268	struct task_struct *task;
	269
	270	__module_get(THIS_MODULE);
	271	atomic_inc(&clp->cl_count);
	272	task = kthread_run(nfs_do_expire_all_delegations, clp,
	273	"%u.%u.%u.%u-delegreturn",
	274	NIPQUAD(clp->cl_addr));
	275	if (!IS_ERR(task))
	276	return;
	277	nfs4_put_client(clp);
	278	module_put(THIS_MODULE);
	279	}
	280
1da177e4 LT	281	/*
	282	* Return all delegations following an NFS4ERR_CB_PATH_DOWN error.
	283	*/
	284	void nfs_handle_cb_pathdown(struct nfs4_client *clp)
	285	{
	286	struct nfs_delegation *delegation;
	287	struct inode *inode;
	288
	289	if (clp == NULL)
	290	return;
	291	restart:
	292	spin_lock(&clp->cl_lock);
	293	list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
	294	inode = igrab(delegation->inode);
	295	if (inode == NULL)
	296	continue;
	297	spin_unlock(&clp->cl_lock);
	298	nfs_inode_return_delegation(inode);
	299	iput(inode);
	300	goto restart;
	301	}
	302	spin_unlock(&clp->cl_lock);
	303	}
	304
	305	struct recall_threadargs {
	306	struct inode *inode;
	307	struct nfs4_client *clp;
	308	const nfs4_stateid *stateid;
	309
	310	struct completion started;
	311	int result;
	312	};
	313
	314	static int recall_thread(void *data)
	315	{
	316	struct recall_threadargs args = (struct recall_threadargs )data;
	317	struct inode *inode = igrab(args->inode);
	318	struct nfs4_client *clp = NFS_SERVER(inode)->nfs4_state;
	319	struct nfs_inode *nfsi = NFS_I(inode);
	320	struct nfs_delegation *delegation;
	321
	322	daemonize("nfsv4-delegreturn");
	323
	324	nfs_msync_inode(inode);
	325	down_read(&clp->cl_sem);
	326	down_write(&nfsi->rwsem);
	327	spin_lock(&clp->cl_lock);
	328	delegation = nfsi->delegation;
	329	if (delegation != NULL && memcmp(delegation->stateid.data,
	330	args->stateid->data,
	331	sizeof(delegation->stateid.data)) == 0) {
	332	list_del_init(&delegation->super_list);
	333	nfsi->delegation = NULL;
	334	nfsi->delegation_state = 0;
	335	args->result = 0;
	336	} else {
	337	delegation = NULL;
	338	args->result = -ENOENT;
	339	}
	340	spin_unlock(&clp->cl_lock);
	341	complete(&args->started);
	342	nfs_delegation_claim_opens(inode);
	343	up_write(&nfsi->rwsem);
	344	up_read(&clp->cl_sem);
345	nfs_msync_inode(inode);
346
347	if (delegation != NULL)
348	nfs_do_return_delegation(inode, delegation);
349	iput(inode);
350	module_put_and_exit(0);
351	}
352
353	/*
354	* Asynchronous delegation recall!
355	*/
356	int nfs_async_inode_return_delegation(struct inode inode, const nfs4_stateid stateid)
357	{
358	struct recall_threadargs data = {
359	.inode = inode,
360	.stateid = stateid,
361	};
362	int status;
363
364	init_completion(&data.started);
365	__module_get(THIS_MODULE);
366	status = kernel_thread(recall_thread, &data, CLONE_KERNEL);
367	if (status < 0)
368	goto out_module_put;
369	wait_for_completion(&data.started);
370	return data.result;
371	out_module_put:
372	module_put(THIS_MODULE);
373	return status;
374	}
375
376	/*
377	* Retrieve the inode associated with a delegation
378	*/
379	struct inode nfs_delegation_find_inode(struct nfs4_client clp, const struct nfs_fh *fhandle)
380	{
381	struct nfs_delegation *delegation;
382	struct inode *res = NULL;
383	spin_lock(&clp->cl_lock);
384	list_for_each_entry(delegation, &clp->cl_delegations, super_list) {
385	if (nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
386	res = igrab(delegation->inode);
387	break;
388	}
389	}
390	spin_unlock(&clp->cl_lock);
391	return res;
392	}
393
394	/*
395	* Mark all delegations as needing to be reclaimed
396	*/
397	void nfs_delegation_mark_reclaim(struct nfs4_client *clp)
398	{
399	struct nfs_delegation *delegation;
400	spin_lock(&clp->cl_lock);
401	list_for_each_entry(delegation, &clp->cl_delegations, super_list)
402	delegation->flags \|= NFS_DELEGATION_NEED_RECLAIM;
403	spin_unlock(&clp->cl_lock);
404	}
405
406	/*
407	* Reap all unclaimed delegations after reboot recovery is done
408	*/
409	void nfs_delegation_reap_unclaimed(struct nfs4_client *clp)
410	{
411	struct nfs_delegation delegation, n;
412	LIST_HEAD(head);
413	spin_lock(&clp->cl_lock);
414	list_for_each_entry_safe(delegation, n, &clp->cl_delegations, super_list) {
415	if ((delegation->flags & NFS_DELEGATION_NEED_RECLAIM) == 0)
416	continue;
417	list_move(&delegation->super_list, &head);
418	NFS_I(delegation->inode)->delegation = NULL;
419	NFS_I(delegation->inode)->delegation_state = 0;
420	}
421	spin_unlock(&clp->cl_lock);
422	while(!list_empty(&head)) {
423	delegation = list_entry(head.next, struct nfs_delegation, super_list);
424	list_del(&delegation->super_list);
425	nfs_free_delegation(delegation);
426	}
427	}