[mirror_ubuntu-zesty-kernel.git] / fs / nfs / nfs4session.c

/*
 * fs/nfs/nfs4session.c
 *
 * Copyright (c) 2012 Trond Myklebust <Trond.Myklebust@netapp.com>
 *
 */
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/bc_xprt.h>
#include <linux/nfs.h>
#include <linux/nfs4.h>
#include <linux/nfs_fs.h>
#include <linux/module.h>

#include "nfs4_fs.h"
#include "internal.h"
#include "nfs4session.h"
#include "callback.h"

#define NFSDBG_FACILITY		NFSDBG_STATE

static void nfs4_init_slot_table(struct nfs4_slot_table *tbl, const char *queue)
{
	tbl->highest_used_slotid = NFS4_NO_SLOT;
	spin_lock_init(&tbl->slot_tbl_lock);
	rpc_init_priority_wait_queue(&tbl->slot_tbl_waitq, queue);
	init_completion(&tbl->complete);
}

/*
 * nfs4_shrink_slot_table - free retired slots from the slot table
 */
static void nfs4_shrink_slot_table(struct nfs4_slot_table  *tbl, u32 newsize)
{
	struct nfs4_slot **p;
	if (newsize >= tbl->max_slots)
		return;

	p = &tbl->slots;
	while (newsize--)
		p = &(*p)->next;
	while (*p) {
		struct nfs4_slot *slot = *p;

		*p = slot->next;
		kfree(slot);
		tbl->max_slots--;
	}
}

/**
 * nfs4_slot_tbl_drain_complete - wake waiters when drain is complete
 * @tbl - controlling slot table
 *
 */
void nfs4_slot_tbl_drain_complete(struct nfs4_slot_table *tbl)
{
	if (nfs4_slot_tbl_draining(tbl))
		complete(&tbl->complete);
}

/*
 * nfs4_free_slot - free a slot and efficiently update slot table.
 *
 * freeing a slot is trivially done by clearing its respective bit
 * in the bitmap.
 * If the freed slotid equals highest_used_slotid we want to update it
 * so that the server would be able to size down the slot table if needed,
 * otherwise we know that the highest_used_slotid is still in use.
 * When updating highest_used_slotid there may be "holes" in the bitmap
 * so we need to scan down from highest_used_slotid to 0 looking for the now
 * highest slotid in use.
 * If none found, highest_used_slotid is set to NFS4_NO_SLOT.
 *
 * Must be called while holding tbl->slot_tbl_lock
 */
void nfs4_free_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
{
	u32 slotid = slot->slot_nr;

	/* clear used bit in bitmap */
	__clear_bit(slotid, tbl->used_slots);

	/* update highest_used_slotid when it is freed */
	if (slotid == tbl->highest_used_slotid) {
		u32 new_max = find_last_bit(tbl->used_slots, slotid);
		if (new_max < slotid)
			tbl->highest_used_slotid = new_max;
		else {
			tbl->highest_used_slotid = NFS4_NO_SLOT;
			nfs4_slot_tbl_drain_complete(tbl);
		}
	}
	dprintk("%s: slotid %u highest_used_slotid %u\n", __func__,
		slotid, tbl->highest_used_slotid);
}

static struct nfs4_slot *nfs4_new_slot(struct nfs4_slot_table  *tbl,
		u32 slotid, u32 seq_init, gfp_t gfp_mask)
{
	struct nfs4_slot *slot;

	slot = kzalloc(sizeof(*slot), gfp_mask);
	if (slot) {
		slot->table = tbl;
		slot->slot_nr = slotid;
		slot->seq_nr = seq_init;
	}
	return slot;
}

static struct nfs4_slot *nfs4_find_or_create_slot(struct nfs4_slot_table  *tbl,
		u32 slotid, u32 seq_init, gfp_t gfp_mask)
{
	struct nfs4_slot **p, *slot;

	p = &tbl->slots;
	for (;;) {
		if (*p == NULL) {
			*p = nfs4_new_slot(tbl, tbl->max_slots,
					seq_init, gfp_mask);
			if (*p == NULL)
				break;
			tbl->max_slots++;
		}
		slot = *p;
		if (slot->slot_nr == slotid)
			return slot;
		p = &slot->next;
	}
	return ERR_PTR(-ENOMEM);
}

/*
 * nfs4_alloc_slot - efficiently look for a free slot
 *
 * nfs4_alloc_slot looks for an unset bit in the used_slots bitmap.
 * If found, we mark the slot as used, update the highest_used_slotid,
 * and respectively set up the sequence operation args.
 *
 * Note: must be called with under the slot_tbl_lock.
 */
struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
{
	struct nfs4_slot *ret = ERR_PTR(-EBUSY);
	u32 slotid;

	dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
		__func__, tbl->used_slots[0], tbl->highest_used_slotid,
		tbl->max_slotid + 1);
	slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
	if (slotid > tbl->max_slotid)
		goto out;
	ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
	if (IS_ERR(ret))
		goto out;
	__set_bit(slotid, tbl->used_slots);
	if (slotid > tbl->highest_used_slotid ||
			tbl->highest_used_slotid == NFS4_NO_SLOT)
		tbl->highest_used_slotid = slotid;
	ret->generation = tbl->generation;

out:
	dprintk("<-- %s used_slots=%04lx highest_used=%u slotid=%u\n",
		__func__, tbl->used_slots[0], tbl->highest_used_slotid,
		!IS_ERR(ret) ? ret->slot_nr : NFS4_NO_SLOT);
	return ret;
}

static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
		 u32 max_reqs, u32 ivalue)
{
	if (max_reqs <= tbl->max_slots)
		return 0;
	if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
		return 0;
	return -ENOMEM;
}

static void nfs4_reset_slot_table(struct nfs4_slot_table *tbl,
		u32 server_highest_slotid,
		u32 ivalue)
{
	struct nfs4_slot **p;

	nfs4_shrink_slot_table(tbl, server_highest_slotid + 1);
	p = &tbl->slots;
	while (*p) {
		(*p)->seq_nr = ivalue;
		(*p)->interrupted = 0;
		p = &(*p)->next;
	}
	tbl->highest_used_slotid = NFS4_NO_SLOT;
	tbl->target_highest_slotid = server_highest_slotid;
	tbl->server_highest_slotid = server_highest_slotid;
	tbl->d_target_highest_slotid = 0;
	tbl->d2_target_highest_slotid = 0;
	tbl->max_slotid = server_highest_slotid;
}

/*
 * (re)Initialise a slot table
 */
static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl,
		u32 max_reqs, u32 ivalue)
{
	int ret;

	dprintk("--> %s: max_reqs=%u, tbl->max_slots %u\n", __func__,
		max_reqs, tbl->max_slots);

	if (max_reqs > NFS4_MAX_SLOT_TABLE)
		max_reqs = NFS4_MAX_SLOT_TABLE;

	ret = nfs4_grow_slot_table(tbl, max_reqs, ivalue);
	if (ret)
		goto out;

	spin_lock(&tbl->slot_tbl_lock);
	nfs4_reset_slot_table(tbl, max_reqs - 1, ivalue);
	spin_unlock(&tbl->slot_tbl_lock);

	dprintk("%s: tbl=%p slots=%p max_slots=%u\n", __func__,
		tbl, tbl->slots, tbl->max_slots);
out:
	dprintk("<-- %s: return %d\n", __func__, ret);
	return ret;
}

/**
 * nfs4_release_slot_table - release resources attached to a slot table
 * @tbl: slot table to shut down
 *
 */
void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
{
	nfs4_shrink_slot_table(tbl, 0);
}

/**
 * nfs4_setup_slot_table - prepare a stand-alone slot table for use
 * @tbl: slot table to set up
 * @max_reqs: maximum number of requests allowed
 * @queue: name to give RPC wait queue
 *
 * Returns zero on success, or a negative errno.
 */
int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
		const char *queue)
{
	nfs4_init_slot_table(tbl, queue);
	return nfs4_realloc_slot_table(tbl, max_reqs, 0);
}

static bool nfs41_assign_slot(struct rpc_task *task, void *pslot)
{
	struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
	struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
	struct nfs4_slot *slot = pslot;
	struct nfs4_slot_table *tbl = slot->table;

	if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
		return false;
	slot->generation = tbl->generation;
	args->sa_slot = slot;
	res->sr_timestamp = jiffies;
	res->sr_slot = slot;
	res->sr_status_flags = 0;
	res->sr_status = 1;
	return true;
}

static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
		struct nfs4_slot *slot)
{
	if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
		return true;
	return false;
}

bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
		struct nfs4_slot *slot)
{
	if (slot->slot_nr > tbl->max_slotid)
		return false;
	return __nfs41_wake_and_assign_slot(tbl, slot);
}

static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
{
	struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
	if (!IS_ERR(slot)) {
		bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
		if (ret)
			return ret;
		nfs4_free_slot(tbl, slot);
	}
	return false;
}

void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
{
	for (;;) {
		if (!nfs41_try_wake_next_slot_table_entry(tbl))
			break;
	}
}

#if defined(CONFIG_NFS_V4_1)

static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
		u32 target_highest_slotid)
{
	u32 max_slotid;

	max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
	if (max_slotid > tbl->server_highest_slotid)
		max_slotid = tbl->server_highest_slotid;
	if (max_slotid > tbl->target_highest_slotid)
		max_slotid = tbl->target_highest_slotid;
	tbl->max_slotid = max_slotid;
	nfs41_wake_slot_table(tbl);
}

/* Update the client's idea of target_highest_slotid */
static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
		u32 target_highest_slotid)
{
	if (tbl->target_highest_slotid == target_highest_slotid)
		return;
	tbl->target_highest_slotid = target_highest_slotid;
	tbl->generation++;
}

void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
		u32 target_highest_slotid)
{
	spin_lock(&tbl->slot_tbl_lock);
	nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
	tbl->d_target_highest_slotid = 0;
	tbl->d2_target_highest_slotid = 0;
	nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
	spin_unlock(&tbl->slot_tbl_lock);
}

static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
		u32 highest_slotid)
{
	if (tbl->server_highest_slotid == highest_slotid)
		return;
	if (tbl->highest_used_slotid > highest_slotid)
		return;
	/* Deallocate slots */
	nfs4_shrink_slot_table(tbl, highest_slotid + 1);
	tbl->server_highest_slotid = highest_slotid;
}

static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
{
	s1 -= s2;
	if (s1 == 0)
		return 0;
	if (s1 < 0)
		return (s1 - 1) >> 1;
	return (s1 + 1) >> 1;
}

static int nfs41_sign_s32(s32 s1)
{
	if (s1 > 0)
		return 1;
	if (s1 < 0)
		return -1;
	return 0;
}

static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
{
	if (!s1 || !s2)
		return true;
	return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
}

/* Try to eliminate outliers by checking for sharp changes in the
 * derivatives and second derivatives
 */
static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
		u32 new_target)
{
	s32 d_target, d2_target;
	bool ret = true;

	d_target = nfs41_derivative_target_slotid(new_target,
			tbl->target_highest_slotid);
	d2_target = nfs41_derivative_target_slotid(d_target,
			tbl->d_target_highest_slotid);
	/* Is first derivative same sign? */
	if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
		ret = false;
	/* Is second derivative same sign? */
	if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
		ret = false;
	tbl->d_target_highest_slotid = d_target;
	tbl->d2_target_highest_slotid = d2_target;
	return ret;
}

void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
		struct nfs4_slot *slot,
		struct nfs4_sequence_res *res)
{
	spin_lock(&tbl->slot_tbl_lock);
	if (!nfs41_is_outlier_target_slotid(tbl, res->sr_target_highest_slotid))
		nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
	if (tbl->generation == slot->generation)
		nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
	nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
	spin_unlock(&tbl->slot_tbl_lock);
}

static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
{
	nfs4_release_slot_table(&session->fc_slot_table);
	nfs4_release_slot_table(&session->bc_slot_table);
}

/*
 * Initialize or reset the forechannel and backchannel tables
 */
int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
{
	struct nfs4_slot_table *tbl;
	int status;

	dprintk("--> %s\n", __func__);
	/* Fore channel */
	tbl = &ses->fc_slot_table;
	tbl->session = ses;
	status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
	if (status) /* -ENOMEM */
		return status;
	/* Back channel */
	tbl = &ses->bc_slot_table;
	tbl->session = ses;
	status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
	if (status && tbl->slots == NULL)
		/* Fore and back channel share a connection so get
		 * both slot tables or neither */
		nfs4_destroy_session_slot_tables(ses);
	return status;
}

struct nfs4_session *nfs4_alloc_session(struct nfs_client *clp)
{
	struct nfs4_session *session;

	session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
	if (!session)
		return NULL;

	nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
	nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
	session->session_state = 1<<NFS4_SESSION_INITING;

	session->clp = clp;
	return session;
}

void nfs4_destroy_session(struct nfs4_session *session)
{
	struct rpc_xprt *xprt;
	struct rpc_cred *cred;

	cred = nfs4_get_clid_cred(session->clp);
	nfs4_proc_destroy_session(session, cred);
	if (cred)
		put_rpccred(cred);

	rcu_read_lock();
	xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
	rcu_read_unlock();
	dprintk("%s Destroy backchannel for xprt %p\n",
		__func__, xprt);
	xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
	nfs4_destroy_session_slot_tables(session);
	kfree(session);
}

/*
 * With sessions, the client is not marked ready until after a
 * successful EXCHANGE_ID and CREATE_SESSION.
 *
 * Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
 * other versions of NFS can be tried.
 */
static int nfs41_check_session_ready(struct nfs_client *clp)
{
	int ret;
	
	if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
		ret = nfs4_client_recover_expired_lease(clp);
		if (ret)
			return ret;
	}
	if (clp->cl_cons_state < NFS_CS_READY)
		return -EPROTONOSUPPORT;
	smp_rmb();
	return 0;
}

int nfs4_init_session(struct nfs_client *clp)
{
	if (!nfs4_has_session(clp))
		return 0;

	clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
	return nfs41_check_session_ready(clp);
}

int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
{
	struct nfs4_session *session = clp->cl_session;
	int ret;

	spin_lock(&clp->cl_lock);
	if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
		/*
		 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the
		 * DS lease to be equal to the MDS lease.
		 */
		clp->cl_lease_time = lease_time;
		clp->cl_last_renewal = jiffies;
	}
	spin_unlock(&clp->cl_lock);

	ret = nfs41_check_session_ready(clp);
	if (ret)
		return ret;
	/* Test for the DS role */
	if (!is_ds_client(clp))
		return -ENODEV;
	return 0;
}
EXPORT_SYMBOL_GPL(nfs4_init_ds_session);

#endif	/* defined(CONFIG_NFS_V4_1) */
Commit	Line	Data
73e39aaa TM	1	/*
	2	* fs/nfs/nfs4session.c
	3	*
	4	* Copyright (c) 2012 Trond Myklebust <Trond.Myklebust@netapp.com>
	5	*
	6	*/
	7	#include <linux/kernel.h>
	8	#include <linux/errno.h>
	9	#include <linux/string.h>
	10	#include <linux/printk.h>
	11	#include <linux/slab.h>
	12	#include <linux/sunrpc/sched.h>
	13	#include <linux/sunrpc/bc_xprt.h>
	14	#include <linux/nfs.h>
	15	#include <linux/nfs4.h>
	16	#include <linux/nfs_fs.h>
	17	#include <linux/module.h>
	18
	19	#include "nfs4_fs.h"
	20	#include "internal.h"
	21	#include "nfs4session.h"
	22	#include "callback.h"
	23
	24	#define NFSDBG_FACILITY NFSDBG_STATE
	25
744aa525 CL	26	static void nfs4_init_slot_table(struct nfs4_slot_table tbl, const char queue)
	27	{
	28	tbl->highest_used_slotid = NFS4_NO_SLOT;
	29	spin_lock_init(&tbl->slot_tbl_lock);
	30	rpc_init_priority_wait_queue(&tbl->slot_tbl_waitq, queue);
	31	init_completion(&tbl->complete);
	32	}
	33
73e39aaa TM	34	/*
	35	* nfs4_shrink_slot_table - free retired slots from the slot table
	36	*/
	37	static void nfs4_shrink_slot_table(struct nfs4_slot_table *tbl, u32 newsize)
	38	{
	39	struct nfs4_slot **p;
	40	if (newsize >= tbl->max_slots)
	41	return;
	42
	43	p = &tbl->slots;
	44	while (newsize--)
	45	p = &(*p)->next;
	46	while (*p) {
	47	struct nfs4_slot slot = p;
	48
	49	*p = slot->next;
	50	kfree(slot);
	51	tbl->max_slots--;
	52	}
	53	}
	54
9d33059c CL	55	/**
	56	* nfs4_slot_tbl_drain_complete - wake waiters when drain is complete
	57	* @tbl - controlling slot table
	58	*
	59	*/
	60	void nfs4_slot_tbl_drain_complete(struct nfs4_slot_table *tbl)
	61	{
	62	if (nfs4_slot_tbl_draining(tbl))
	63	complete(&tbl->complete);
	64	}
	65
73e39aaa TM	66	/*
	67	* nfs4_free_slot - free a slot and efficiently update slot table.
	68	*
	69	* freeing a slot is trivially done by clearing its respective bit
	70	* in the bitmap.
	71	* If the freed slotid equals highest_used_slotid we want to update it
	72	* so that the server would be able to size down the slot table if needed,
	73	* otherwise we know that the highest_used_slotid is still in use.
	74	* When updating highest_used_slotid there may be "holes" in the bitmap
	75	* so we need to scan down from highest_used_slotid to 0 looking for the now
	76	* highest slotid in use.
	77	* If none found, highest_used_slotid is set to NFS4_NO_SLOT.
	78	*
	79	* Must be called while holding tbl->slot_tbl_lock
	80	*/
	81	void nfs4_free_slot(struct nfs4_slot_table tbl, struct nfs4_slot slot)
	82	{
	83	u32 slotid = slot->slot_nr;
	84
	85	/* clear used bit in bitmap */
	86	__clear_bit(slotid, tbl->used_slots);
	87
	88	/* update highest_used_slotid when it is freed */
	89	if (slotid == tbl->highest_used_slotid) {
	90	u32 new_max = find_last_bit(tbl->used_slots, slotid);
	91	if (new_max < slotid)
	92	tbl->highest_used_slotid = new_max;
	93	else {
	94	tbl->highest_used_slotid = NFS4_NO_SLOT;
774d5f14	95	nfs4_slot_tbl_drain_complete(tbl);
73e39aaa TM	96	}
73e39aaa TM	97	}
e8d92382	98	dprintk("%s: slotid %u highest_used_slotid %u\n", __func__,
73e39aaa TM	99	slotid, tbl->highest_used_slotid);
	100	}
	101
	102	static struct nfs4_slot nfs4_new_slot(struct nfs4_slot_table tbl,
	103	u32 slotid, u32 seq_init, gfp_t gfp_mask)
	104	{
	105	struct nfs4_slot *slot;
	106
	107	slot = kzalloc(sizeof(*slot), gfp_mask);
	108	if (slot) {
	109	slot->table = tbl;
	110	slot->slot_nr = slotid;
	111	slot->seq_nr = seq_init;
	112	}
	113	return slot;
	114	}
	115
	116	static struct nfs4_slot nfs4_find_or_create_slot(struct nfs4_slot_table tbl,
	117	u32 slotid, u32 seq_init, gfp_t gfp_mask)
	118	{
	119	struct nfs4_slot *p, slot;
	120
	121	p = &tbl->slots;
	122	for (;;) {
	123	if (*p == NULL) {
	124	*p = nfs4_new_slot(tbl, tbl->max_slots,
	125	seq_init, gfp_mask);
	126	if (*p == NULL)
	127	break;
	128	tbl->max_slots++;
	129	}
	130	slot = *p;
	131	if (slot->slot_nr == slotid)
	132	return slot;
	133	p = &slot->next;
	134	}
	135	return ERR_PTR(-ENOMEM);
	136	}
	137
	138	/*
	139	* nfs4_alloc_slot - efficiently look for a free slot
	140	*
	141	* nfs4_alloc_slot looks for an unset bit in the used_slots bitmap.
	142	* If found, we mark the slot as used, update the highest_used_slotid,
	143	* and respectively set up the sequence operation args.
	144	*
	145	* Note: must be called with under the slot_tbl_lock.
	146	*/
	147	struct nfs4_slot nfs4_alloc_slot(struct nfs4_slot_table tbl)
	148	{
	149	struct nfs4_slot *ret = ERR_PTR(-EBUSY);
	150	u32 slotid;
	151
	152	dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
	153	__func__, tbl->used_slots[0], tbl->highest_used_slotid,
	154	tbl->max_slotid + 1);
	155	slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
	156	if (slotid > tbl->max_slotid)
	157	goto out;
	158	ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
	159	if (IS_ERR(ret))
	160	goto out;
	161	__set_bit(slotid, tbl->used_slots);
	162	if (slotid > tbl->highest_used_slotid \|\|
163	tbl->highest_used_slotid == NFS4_NO_SLOT)
164	tbl->highest_used_slotid = slotid;
73e39aaa TM	165	ret->generation = tbl->generation;
	166
	167	out:
e8d92382	168	dprintk("<-- %s used_slots=%04lx highest_used=%u slotid=%u\n",
73e39aaa	169	__func__, tbl->used_slots[0], tbl->highest_used_slotid,
e8d92382	170	!IS_ERR(ret) ? ret->slot_nr : NFS4_NO_SLOT);
73e39aaa TM	171	return ret;
	172	}
	173
	174	static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
	175	u32 max_reqs, u32 ivalue)
	176	{
	177	if (max_reqs <= tbl->max_slots)
	178	return 0;
	179	if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
	180	return 0;
	181	return -ENOMEM;
	182	}
	183
	184	static void nfs4_reset_slot_table(struct nfs4_slot_table *tbl,
	185	u32 server_highest_slotid,
	186	u32 ivalue)
	187	{
	188	struct nfs4_slot **p;
	189
	190	nfs4_shrink_slot_table(tbl, server_highest_slotid + 1);
	191	p = &tbl->slots;
	192	while (*p) {
	193	(*p)->seq_nr = ivalue;
ac20d163	194	(*p)->interrupted = 0;
73e39aaa TM	195	p = &(*p)->next;
	196	}
	197	tbl->highest_used_slotid = NFS4_NO_SLOT;
	198	tbl->target_highest_slotid = server_highest_slotid;
	199	tbl->server_highest_slotid = server_highest_slotid;
1fa80644 TM	200	tbl->d_target_highest_slotid = 0;
1fa80644 TM	201	tbl->d2_target_highest_slotid = 0;
73e39aaa TM	202	tbl->max_slotid = server_highest_slotid;
	203	}
	204
	205	/*
	206	* (re)Initialise a slot table
	207	*/
	208	static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl,
	209	u32 max_reqs, u32 ivalue)
	210	{
	211	int ret;
	212
e8d92382	213	dprintk("--> %s: max_reqs=%u, tbl->max_slots %u\n", __func__,
73e39aaa TM	214	max_reqs, tbl->max_slots);
	215
	216	if (max_reqs > NFS4_MAX_SLOT_TABLE)
	217	max_reqs = NFS4_MAX_SLOT_TABLE;
	218
	219	ret = nfs4_grow_slot_table(tbl, max_reqs, ivalue);
	220	if (ret)
	221	goto out;
	222
	223	spin_lock(&tbl->slot_tbl_lock);
	224	nfs4_reset_slot_table(tbl, max_reqs - 1, ivalue);
	225	spin_unlock(&tbl->slot_tbl_lock);
	226
e8d92382	227	dprintk("%s: tbl=%p slots=%p max_slots=%u\n", __func__,
73e39aaa TM	228	tbl, tbl->slots, tbl->max_slots);
	229	out:
	230	dprintk("<-- %s: return %d\n", __func__, ret);
	231	return ret;
	232	}
	233
eb2a1cd3 CL	234	/**
	235	* nfs4_release_slot_table - release resources attached to a slot table
	236	* @tbl: slot table to shut down
	237	*
	238	*/
	239	void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
	240	{
	241	nfs4_shrink_slot_table(tbl, 0);
	242	}
	243
744aa525 CL	244	/**
	245	* nfs4_setup_slot_table - prepare a stand-alone slot table for use
	246	* @tbl: slot table to set up
	247	* @max_reqs: maximum number of requests allowed
	248	* @queue: name to give RPC wait queue
	249	*
	250	* Returns zero on success, or a negative errno.
	251	*/
	252	int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
	253	const char *queue)
	254	{
	255	nfs4_init_slot_table(tbl, queue);
	256	return nfs4_realloc_slot_table(tbl, max_reqs, 0);
	257	}
	258
b75ad4cd TM	259	static bool nfs41_assign_slot(struct rpc_task task, void pslot)
	260	{
	261	struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
	262	struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
	263	struct nfs4_slot *slot = pslot;
	264	struct nfs4_slot_table *tbl = slot->table;
	265
774d5f14	266	if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
b75ad4cd	267	return false;
b75ad4cd TM	268	slot->generation = tbl->generation;
b75ad4cd TM	269	args->sa_slot = slot;
8e63b6a8	270	res->sr_timestamp = jiffies;
b75ad4cd TM	271	res->sr_slot = slot;
	272	res->sr_status_flags = 0;
	273	res->sr_status = 1;
	274	return true;
	275	}
	276
	277	static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
	278	struct nfs4_slot *slot)
	279	{
	280	if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
	281	return true;
	282	return false;
	283	}
	284
	285	bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
	286	struct nfs4_slot *slot)
	287	{
	288	if (slot->slot_nr > tbl->max_slotid)
	289	return false;
	290	return __nfs41_wake_and_assign_slot(tbl, slot);
	291	}
	292
	293	static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
	294	{
	295	struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
	296	if (!IS_ERR(slot)) {
	297	bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
	298	if (ret)
	299	return ret;
	300	nfs4_free_slot(tbl, slot);
	301	}
	302	return false;
	303	}
	304
	305	void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
	306	{
	307	for (;;) {
	308	if (!nfs41_try_wake_next_slot_table_entry(tbl))
	309	break;
	310	}
	311	}
	312
1cec16ab CL	313	#if defined(CONFIG_NFS_V4_1)
1cec16ab CL	314
b0ef9647 TM	315	static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
	316	u32 target_highest_slotid)
	317	{
	318	u32 max_slotid;
	319
	320	max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
	321	if (max_slotid > tbl->server_highest_slotid)
	322	max_slotid = tbl->server_highest_slotid;
	323	if (max_slotid > tbl->target_highest_slotid)
	324	max_slotid = tbl->target_highest_slotid;
	325	tbl->max_slotid = max_slotid;
	326	nfs41_wake_slot_table(tbl);
	327	}
	328
73e39aaa TM	329	/* Update the client's idea of target_highest_slotid */
	330	static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
	331	u32 target_highest_slotid)
	332	{
73e39aaa TM	333	if (tbl->target_highest_slotid == target_highest_slotid)
	334	return;
	335	tbl->target_highest_slotid = target_highest_slotid;
	336	tbl->generation++;
73e39aaa TM	337	}
	338
	339	void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
	340	u32 target_highest_slotid)
	341	{
	342	spin_lock(&tbl->slot_tbl_lock);
	343	nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
1fa80644 TM	344	tbl->d_target_highest_slotid = 0;
1fa80644 TM	345	tbl->d2_target_highest_slotid = 0;
b0ef9647	346	nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
73e39aaa TM	347	spin_unlock(&tbl->slot_tbl_lock);
	348	}
	349
	350	static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
	351	u32 highest_slotid)
	352	{
	353	if (tbl->server_highest_slotid == highest_slotid)
	354	return;
	355	if (tbl->highest_used_slotid > highest_slotid)
	356	return;
	357	/* Deallocate slots */
	358	nfs4_shrink_slot_table(tbl, highest_slotid + 1);
	359	tbl->server_highest_slotid = highest_slotid;
	360	}
	361
1fa80644 TM	362	static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
	363	{
	364	s1 -= s2;
	365	if (s1 == 0)
	366	return 0;
	367	if (s1 < 0)
	368	return (s1 - 1) >> 1;
	369	return (s1 + 1) >> 1;
	370	}
	371
	372	static int nfs41_sign_s32(s32 s1)
	373	{
	374	if (s1 > 0)
	375	return 1;
	376	if (s1 < 0)
	377	return -1;
	378	return 0;
	379	}
	380
	381	static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
	382	{
	383	if (!s1 \|\| !s2)
	384	return true;
	385	return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
	386	}
	387
	388	/* Try to eliminate outliers by checking for sharp changes in the
	389	* derivatives and second derivatives
	390	*/
	391	static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
	392	u32 new_target)
	393	{
	394	s32 d_target, d2_target;
	395	bool ret = true;
	396
	397	d_target = nfs41_derivative_target_slotid(new_target,
	398	tbl->target_highest_slotid);
	399	d2_target = nfs41_derivative_target_slotid(d_target,
	400	tbl->d_target_highest_slotid);
	401	/* Is first derivative same sign? */
	402	if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
	403	ret = false;
	404	/* Is second derivative same sign? */
	405	if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
	406	ret = false;
	407	tbl->d_target_highest_slotid = d_target;
	408	tbl->d2_target_highest_slotid = d2_target;
	409	return ret;
	410	}
	411
73e39aaa TM	412	void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
	413	struct nfs4_slot *slot,
	414	struct nfs4_sequence_res *res)
	415	{
	416	spin_lock(&tbl->slot_tbl_lock);
1fa80644 TM	417	if (!nfs41_is_outlier_target_slotid(tbl, res->sr_target_highest_slotid))
	418	nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
	419	if (tbl->generation == slot->generation)
	420	nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
b0ef9647	421	nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
73e39aaa TM	422	spin_unlock(&tbl->slot_tbl_lock);
	423	}
	424
eb2a1cd3	425	static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
9d33059c	426	{
eb2a1cd3 CL	427	nfs4_release_slot_table(&session->fc_slot_table);
eb2a1cd3 CL	428	nfs4_release_slot_table(&session->bc_slot_table);
9d33059c CL	429	}
9d33059c CL	430
73e39aaa TM	431	/*
	432	* Initialize or reset the forechannel and backchannel tables
	433	*/
	434	int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
	435	{
	436	struct nfs4_slot_table *tbl;
	437	int status;
	438
	439	dprintk("--> %s\n", __func__);
	440	/* Fore channel */
	441	tbl = &ses->fc_slot_table;
	442	tbl->session = ses;
	443	status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
	444	if (status) /* -ENOMEM */
	445	return status;
	446	/* Back channel */
	447	tbl = &ses->bc_slot_table;
	448	tbl->session = ses;
	449	status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
	450	if (status && tbl->slots == NULL)
	451	/* Fore and back channel share a connection so get
	452	* both slot tables or neither */
eb2a1cd3	453	nfs4_destroy_session_slot_tables(ses);
73e39aaa TM	454	return status;
	455	}
	456
	457	struct nfs4_session nfs4_alloc_session(struct nfs_client clp)
	458	{
	459	struct nfs4_session *session;
73e39aaa TM	460
	461	session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
	462	if (!session)
	463	return NULL;
	464
744aa525 CL	465	nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
744aa525 CL	466	nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
73e39aaa TM	467	session->session_state = 1<<NFS4_SESSION_INITING;
	468
	469	session->clp = clp;
	470	return session;
	471	}
	472
	473	void nfs4_destroy_session(struct nfs4_session *session)
	474	{
	475	struct rpc_xprt *xprt;
	476	struct rpc_cred *cred;
	477
73d8bde5	478	cred = nfs4_get_clid_cred(session->clp);
73e39aaa TM	479	nfs4_proc_destroy_session(session, cred);
	480	if (cred)
	481	put_rpccred(cred);
	482
	483	rcu_read_lock();
	484	xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
	485	rcu_read_unlock();
	486	dprintk("%s Destroy backchannel for xprt %p\n",
	487	__func__, xprt);
	488	xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
eb2a1cd3	489	nfs4_destroy_session_slot_tables(session);
73e39aaa TM	490	kfree(session);
	491	}
	492
	493	/*
	494	* With sessions, the client is not marked ready until after a
	495	* successful EXCHANGE_ID and CREATE_SESSION.
	496	*
	497	* Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
	498	* other versions of NFS can be tried.
	499	*/
	500	static int nfs41_check_session_ready(struct nfs_client *clp)
	501	{
	502	int ret;
	503
	504	if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
	505	ret = nfs4_client_recover_expired_lease(clp);
	506	if (ret)
	507	return ret;
	508	}
	509	if (clp->cl_cons_state < NFS_CS_READY)
	510	return -EPROTONOSUPPORT;
	511	smp_rmb();
	512	return 0;
	513	}
	514
18aad3d5	515	int nfs4_init_session(struct nfs_client *clp)
73e39aaa	516	{
73e39aaa TM	517	if (!nfs4_has_session(clp))
	518	return 0;
	519
18aad3d5	520	clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
73e39aaa TM	521	return nfs41_check_session_ready(clp);
	522	}
	523
	524	int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
	525	{
	526	struct nfs4_session *session = clp->cl_session;
	527	int ret;
	528
	529	spin_lock(&clp->cl_lock);
	530	if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
	531	/*
	532	* Do not set NFS_CS_CHECK_LEASE_TIME instead set the
	533	* DS lease to be equal to the MDS lease.
	534	*/
	535	clp->cl_lease_time = lease_time;
	536	clp->cl_last_renewal = jiffies;
	537	}
	538	spin_unlock(&clp->cl_lock);
	539
	540	ret = nfs41_check_session_ready(clp);
	541	if (ret)
	542	return ret;
	543	/* Test for the DS role */
	544	if (!is_ds_client(clp))
	545	return -ENODEV;
	546	return 0;
	547	}
	548	EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
	549
9d33059c	550	#endif /* defined(CONFIG_NFS_V4_1) */