[linux-2.6-block.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);
}

static void nfs4_lock_slot(struct nfs4_slot_table *tbl,
		struct nfs4_slot *slot)
{
	u32 slotid = slot->slot_nr;

	__set_bit(slotid, tbl->used_slots);
	if (slotid > tbl->highest_used_slotid ||
	    tbl->highest_used_slotid == NFS4_NO_SLOT)
		tbl->highest_used_slotid = slotid;
	slot->generation = tbl->generation;
}

/*
 * nfs4_try_to_lock_slot - Given a slot try to allocate it
 *
 * Note: must be called with the slot_tbl_lock held.
 */
bool nfs4_try_to_lock_slot(struct nfs4_slot_table *tbl, struct nfs4_slot *slot)
{
	if (nfs4_test_locked_slot(tbl, slot->slot_nr))
		return false;
	nfs4_lock_slot(tbl, slot);
	return true;
}

/*
 * nfs4_lookup_slot - Find a slot but don't allocate it
 *
 * Note: must be called with the slot_tbl_lock held.
 */
struct nfs4_slot *nfs4_lookup_slot(struct nfs4_slot_table *tbl, u32 slotid)
{
	if (slotid <= tbl->max_slotid)
		return nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
	return ERR_PTR(-E2BIG);
}

/*
 * 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) {
		ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
		if (!IS_ERR(ret))
			nfs4_lock_slot(tbl, ret);
	}
	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 all slot table entries
 */
static void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
{
	nfs4_shrink_slot_table(tbl, 0);
}

/**
 * nfs4_shutdown_slot_table - release resources attached to a slot table
 * @tbl: slot table to shut down
 *
 */
void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl)
{
	nfs4_release_slot_table(tbl);
	rpc_destroy_wait_queue(&tbl->slot_tbl_waitq);
}

/**
 * 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_release_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 || !(ses->flags & SESSION4_BACK_CHAN)) /* -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_release_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;
}

static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
{
	nfs4_shutdown_slot_table(&session->fc_slot_table);
	nfs4_shutdown_slot_table(&session->bc_slot_table);
}

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
810d82e6 TM	138	static void nfs4_lock_slot(struct nfs4_slot_table *tbl,
	139	struct nfs4_slot *slot)
	140	{
	141	u32 slotid = slot->slot_nr;
	142
	143	__set_bit(slotid, tbl->used_slots);
	144	if (slotid > tbl->highest_used_slotid \|\|
	145	tbl->highest_used_slotid == NFS4_NO_SLOT)
	146	tbl->highest_used_slotid = slotid;
	147	slot->generation = tbl->generation;
	148	}
	149
	150	/*
	151	* nfs4_try_to_lock_slot - Given a slot try to allocate it
	152	*
	153	* Note: must be called with the slot_tbl_lock held.
	154	*/
	155	bool nfs4_try_to_lock_slot(struct nfs4_slot_table tbl, struct nfs4_slot slot)
	156	{
	157	if (nfs4_test_locked_slot(tbl, slot->slot_nr))
	158	return false;
	159	nfs4_lock_slot(tbl, slot);
	160	return true;
	161	}
	162
	163	/*
	164	* nfs4_lookup_slot - Find a slot but don't allocate it
	165	*
	166	* Note: must be called with the slot_tbl_lock held.
	167	*/
	168	struct nfs4_slot nfs4_lookup_slot(struct nfs4_slot_table tbl, u32 slotid)
	169	{
	170	if (slotid <= tbl->max_slotid)
	171	return nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
	172	return ERR_PTR(-E2BIG);
	173	}
	174
73e39aaa TM	175	/*
	176	* nfs4_alloc_slot - efficiently look for a free slot
	177	*
	178	* nfs4_alloc_slot looks for an unset bit in the used_slots bitmap.
	179	* If found, we mark the slot as used, update the highest_used_slotid,
	180	* and respectively set up the sequence operation args.
	181	*
	182	* Note: must be called with under the slot_tbl_lock.
	183	*/
	184	struct nfs4_slot nfs4_alloc_slot(struct nfs4_slot_table tbl)
	185	{
	186	struct nfs4_slot *ret = ERR_PTR(-EBUSY);
	187	u32 slotid;
	188
	189	dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
	190	__func__, tbl->used_slots[0], tbl->highest_used_slotid,
	191	tbl->max_slotid + 1);
	192	slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
810d82e6 TM	193	if (slotid <= tbl->max_slotid) {
	194	ret = nfs4_find_or_create_slot(tbl, slotid, 1, GFP_NOWAIT);
	195	if (!IS_ERR(ret))
	196	nfs4_lock_slot(tbl, ret);
	197	}
e8d92382	198	dprintk("<-- %s used_slots=%04lx highest_used=%u slotid=%u\n",
73e39aaa	199	__func__, tbl->used_slots[0], tbl->highest_used_slotid,
e8d92382	200	!IS_ERR(ret) ? ret->slot_nr : NFS4_NO_SLOT);
73e39aaa TM	201	return ret;
	202	}
	203
	204	static int nfs4_grow_slot_table(struct nfs4_slot_table *tbl,
	205	u32 max_reqs, u32 ivalue)
	206	{
	207	if (max_reqs <= tbl->max_slots)
	208	return 0;
	209	if (!IS_ERR(nfs4_find_or_create_slot(tbl, max_reqs - 1, ivalue, GFP_NOFS)))
	210	return 0;
	211	return -ENOMEM;
	212	}
	213
	214	static void nfs4_reset_slot_table(struct nfs4_slot_table *tbl,
	215	u32 server_highest_slotid,
	216	u32 ivalue)
	217	{
	218	struct nfs4_slot **p;
	219
	220	nfs4_shrink_slot_table(tbl, server_highest_slotid + 1);
	221	p = &tbl->slots;
	222	while (*p) {
	223	(*p)->seq_nr = ivalue;
ac20d163	224	(*p)->interrupted = 0;
73e39aaa TM	225	p = &(*p)->next;
	226	}
	227	tbl->highest_used_slotid = NFS4_NO_SLOT;
	228	tbl->target_highest_slotid = server_highest_slotid;
	229	tbl->server_highest_slotid = server_highest_slotid;
1fa80644 TM	230	tbl->d_target_highest_slotid = 0;
1fa80644 TM	231	tbl->d2_target_highest_slotid = 0;
73e39aaa TM	232	tbl->max_slotid = server_highest_slotid;
	233	}
	234
	235	/*
	236	* (re)Initialise a slot table
	237	*/
	238	static int nfs4_realloc_slot_table(struct nfs4_slot_table *tbl,
	239	u32 max_reqs, u32 ivalue)
	240	{
	241	int ret;
	242
e8d92382	243	dprintk("--> %s: max_reqs=%u, tbl->max_slots %u\n", __func__,
73e39aaa TM	244	max_reqs, tbl->max_slots);
	245
	246	if (max_reqs > NFS4_MAX_SLOT_TABLE)
	247	max_reqs = NFS4_MAX_SLOT_TABLE;
	248
	249	ret = nfs4_grow_slot_table(tbl, max_reqs, ivalue);
	250	if (ret)
	251	goto out;
	252
	253	spin_lock(&tbl->slot_tbl_lock);
	254	nfs4_reset_slot_table(tbl, max_reqs - 1, ivalue);
	255	spin_unlock(&tbl->slot_tbl_lock);
	256
e8d92382	257	dprintk("%s: tbl=%p slots=%p max_slots=%u\n", __func__,
73e39aaa TM	258	tbl, tbl->slots, tbl->max_slots);
	259	out:
	260	dprintk("<-- %s: return %d\n", __func__, ret);
	261	return ret;
	262	}
	263
20b9a902 TM	264	/*
	265	* nfs4_release_slot_table - release all slot table entries
	266	*/
	267	static void nfs4_release_slot_table(struct nfs4_slot_table *tbl)
	268	{
	269	nfs4_shrink_slot_table(tbl, 0);
	270	}
	271
eb2a1cd3	272	/**
20b9a902	273	* nfs4_shutdown_slot_table - release resources attached to a slot table
eb2a1cd3 CL	274	* @tbl: slot table to shut down
	275	*
	276	*/
20b9a902	277	void nfs4_shutdown_slot_table(struct nfs4_slot_table *tbl)
eb2a1cd3	278	{
20b9a902 TM	279	nfs4_release_slot_table(tbl);
20b9a902 TM	280	rpc_destroy_wait_queue(&tbl->slot_tbl_waitq);
eb2a1cd3 CL	281	}
eb2a1cd3 CL	282
744aa525 CL	283	/**
	284	* nfs4_setup_slot_table - prepare a stand-alone slot table for use
	285	* @tbl: slot table to set up
	286	* @max_reqs: maximum number of requests allowed
	287	* @queue: name to give RPC wait queue
	288	*
	289	* Returns zero on success, or a negative errno.
	290	*/
	291	int nfs4_setup_slot_table(struct nfs4_slot_table *tbl, unsigned int max_reqs,
	292	const char *queue)
	293	{
	294	nfs4_init_slot_table(tbl, queue);
	295	return nfs4_realloc_slot_table(tbl, max_reqs, 0);
	296	}
	297
b75ad4cd TM	298	static bool nfs41_assign_slot(struct rpc_task task, void pslot)
	299	{
	300	struct nfs4_sequence_args *args = task->tk_msg.rpc_argp;
	301	struct nfs4_sequence_res *res = task->tk_msg.rpc_resp;
	302	struct nfs4_slot *slot = pslot;
	303	struct nfs4_slot_table *tbl = slot->table;
	304
774d5f14	305	if (nfs4_slot_tbl_draining(tbl) && !args->sa_privileged)
b75ad4cd	306	return false;
b75ad4cd TM	307	slot->generation = tbl->generation;
b75ad4cd TM	308	args->sa_slot = slot;
8e63b6a8	309	res->sr_timestamp = jiffies;
b75ad4cd TM	310	res->sr_slot = slot;
	311	res->sr_status_flags = 0;
	312	res->sr_status = 1;
	313	return true;
	314	}
	315
	316	static bool __nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
	317	struct nfs4_slot *slot)
	318	{
	319	if (rpc_wake_up_first(&tbl->slot_tbl_waitq, nfs41_assign_slot, slot))
	320	return true;
	321	return false;
	322	}
	323
	324	bool nfs41_wake_and_assign_slot(struct nfs4_slot_table *tbl,
	325	struct nfs4_slot *slot)
	326	{
	327	if (slot->slot_nr > tbl->max_slotid)
	328	return false;
	329	return __nfs41_wake_and_assign_slot(tbl, slot);
	330	}
	331
	332	static bool nfs41_try_wake_next_slot_table_entry(struct nfs4_slot_table *tbl)
	333	{
	334	struct nfs4_slot *slot = nfs4_alloc_slot(tbl);
	335	if (!IS_ERR(slot)) {
	336	bool ret = __nfs41_wake_and_assign_slot(tbl, slot);
	337	if (ret)
	338	return ret;
	339	nfs4_free_slot(tbl, slot);
	340	}
	341	return false;
	342	}
	343
	344	void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
	345	{
	346	for (;;) {
	347	if (!nfs41_try_wake_next_slot_table_entry(tbl))
	348	break;
	349	}
	350	}
	351
1cec16ab CL	352	#if defined(CONFIG_NFS_V4_1)
1cec16ab CL	353
b0ef9647 TM	354	static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
	355	u32 target_highest_slotid)
	356	{
	357	u32 max_slotid;
	358
	359	max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
	360	if (max_slotid > tbl->server_highest_slotid)
	361	max_slotid = tbl->server_highest_slotid;
	362	if (max_slotid > tbl->target_highest_slotid)
	363	max_slotid = tbl->target_highest_slotid;
	364	tbl->max_slotid = max_slotid;
	365	nfs41_wake_slot_table(tbl);
	366	}
	367
73e39aaa TM	368	/* Update the client's idea of target_highest_slotid */
	369	static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
	370	u32 target_highest_slotid)
	371	{
73e39aaa TM	372	if (tbl->target_highest_slotid == target_highest_slotid)
	373	return;
	374	tbl->target_highest_slotid = target_highest_slotid;
	375	tbl->generation++;
73e39aaa TM	376	}
	377
	378	void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
	379	u32 target_highest_slotid)
	380	{
	381	spin_lock(&tbl->slot_tbl_lock);
	382	nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
1fa80644 TM	383	tbl->d_target_highest_slotid = 0;
1fa80644 TM	384	tbl->d2_target_highest_slotid = 0;
b0ef9647	385	nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
73e39aaa TM	386	spin_unlock(&tbl->slot_tbl_lock);
	387	}
	388
	389	static void nfs41_set_server_slotid_locked(struct nfs4_slot_table *tbl,
	390	u32 highest_slotid)
	391	{
	392	if (tbl->server_highest_slotid == highest_slotid)
	393	return;
	394	if (tbl->highest_used_slotid > highest_slotid)
	395	return;
	396	/* Deallocate slots */
	397	nfs4_shrink_slot_table(tbl, highest_slotid + 1);
	398	tbl->server_highest_slotid = highest_slotid;
	399	}
	400
1fa80644 TM	401	static s32 nfs41_derivative_target_slotid(s32 s1, s32 s2)
	402	{
	403	s1 -= s2;
	404	if (s1 == 0)
	405	return 0;
	406	if (s1 < 0)
	407	return (s1 - 1) >> 1;
	408	return (s1 + 1) >> 1;
	409	}
	410
	411	static int nfs41_sign_s32(s32 s1)
	412	{
	413	if (s1 > 0)
	414	return 1;
	415	if (s1 < 0)
	416	return -1;
	417	return 0;
	418	}
	419
	420	static bool nfs41_same_sign_or_zero_s32(s32 s1, s32 s2)
	421	{
	422	if (!s1 \|\| !s2)
	423	return true;
	424	return nfs41_sign_s32(s1) == nfs41_sign_s32(s2);
	425	}
	426
	427	/* Try to eliminate outliers by checking for sharp changes in the
	428	* derivatives and second derivatives
	429	*/
	430	static bool nfs41_is_outlier_target_slotid(struct nfs4_slot_table *tbl,
	431	u32 new_target)
	432	{
	433	s32 d_target, d2_target;
	434	bool ret = true;
	435
	436	d_target = nfs41_derivative_target_slotid(new_target,
	437	tbl->target_highest_slotid);
	438	d2_target = nfs41_derivative_target_slotid(d_target,
	439	tbl->d_target_highest_slotid);
	440	/* Is first derivative same sign? */
	441	if (nfs41_same_sign_or_zero_s32(d_target, tbl->d_target_highest_slotid))
	442	ret = false;
	443	/* Is second derivative same sign? */
	444	if (nfs41_same_sign_or_zero_s32(d2_target, tbl->d2_target_highest_slotid))
	445	ret = false;
	446	tbl->d_target_highest_slotid = d_target;
	447	tbl->d2_target_highest_slotid = d2_target;
	448	return ret;
	449	}
	450
73e39aaa TM	451	void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
	452	struct nfs4_slot *slot,
	453	struct nfs4_sequence_res *res)
	454	{
	455	spin_lock(&tbl->slot_tbl_lock);
1fa80644 TM	456	if (!nfs41_is_outlier_target_slotid(tbl, res->sr_target_highest_slotid))
	457	nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
	458	if (tbl->generation == slot->generation)
	459	nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
b0ef9647	460	nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
73e39aaa TM	461	spin_unlock(&tbl->slot_tbl_lock);
	462	}
	463
20b9a902	464	static void nfs4_release_session_slot_tables(struct nfs4_session *session)
9d33059c	465	{
eb2a1cd3 CL	466	nfs4_release_slot_table(&session->fc_slot_table);
eb2a1cd3 CL	467	nfs4_release_slot_table(&session->bc_slot_table);
9d33059c CL	468	}
9d33059c CL	469
73e39aaa TM	470	/*
	471	* Initialize or reset the forechannel and backchannel tables
	472	*/
	473	int nfs4_setup_session_slot_tables(struct nfs4_session *ses)
	474	{
	475	struct nfs4_slot_table *tbl;
	476	int status;
	477
	478	dprintk("--> %s\n", __func__);
	479	/* Fore channel */
	480	tbl = &ses->fc_slot_table;
	481	tbl->session = ses;
	482	status = nfs4_realloc_slot_table(tbl, ses->fc_attrs.max_reqs, 1);
b1c0df5f	483	if (status \|\| !(ses->flags & SESSION4_BACK_CHAN)) /* -ENOMEM */
73e39aaa TM	484	return status;
	485	/* Back channel */
	486	tbl = &ses->bc_slot_table;
	487	tbl->session = ses;
	488	status = nfs4_realloc_slot_table(tbl, ses->bc_attrs.max_reqs, 0);
	489	if (status && tbl->slots == NULL)
	490	/* Fore and back channel share a connection so get
	491	* both slot tables or neither */
20b9a902	492	nfs4_release_session_slot_tables(ses);
73e39aaa TM	493	return status;
	494	}
	495
	496	struct nfs4_session nfs4_alloc_session(struct nfs_client clp)
	497	{
	498	struct nfs4_session *session;
73e39aaa TM	499
	500	session = kzalloc(sizeof(struct nfs4_session), GFP_NOFS);
	501	if (!session)
	502	return NULL;
	503
744aa525 CL	504	nfs4_init_slot_table(&session->fc_slot_table, "ForeChannel Slot table");
744aa525 CL	505	nfs4_init_slot_table(&session->bc_slot_table, "BackChannel Slot table");
73e39aaa TM	506	session->session_state = 1<<NFS4_SESSION_INITING;
	507
	508	session->clp = clp;
	509	return session;
	510	}
	511
20b9a902 TM	512	static void nfs4_destroy_session_slot_tables(struct nfs4_session *session)
	513	{
	514	nfs4_shutdown_slot_table(&session->fc_slot_table);
	515	nfs4_shutdown_slot_table(&session->bc_slot_table);
	516	}
	517
73e39aaa TM	518	void nfs4_destroy_session(struct nfs4_session *session)
	519	{
	520	struct rpc_xprt *xprt;
	521	struct rpc_cred *cred;
	522
73d8bde5	523	cred = nfs4_get_clid_cred(session->clp);
73e39aaa TM	524	nfs4_proc_destroy_session(session, cred);
	525	if (cred)
	526	put_rpccred(cred);
	527
	528	rcu_read_lock();
	529	xprt = rcu_dereference(session->clp->cl_rpcclient->cl_xprt);
	530	rcu_read_unlock();
	531	dprintk("%s Destroy backchannel for xprt %p\n",
	532	__func__, xprt);
	533	xprt_destroy_backchannel(xprt, NFS41_BC_MIN_CALLBACKS);
eb2a1cd3	534	nfs4_destroy_session_slot_tables(session);
73e39aaa TM	535	kfree(session);
	536	}
	537
	538	/*
	539	* With sessions, the client is not marked ready until after a
	540	* successful EXCHANGE_ID and CREATE_SESSION.
	541	*
	542	* Map errors cl_cons_state errors to EPROTONOSUPPORT to indicate
	543	* other versions of NFS can be tried.
	544	*/
	545	static int nfs41_check_session_ready(struct nfs_client *clp)
	546	{
	547	int ret;
	548
	549	if (clp->cl_cons_state == NFS_CS_SESSION_INITING) {
	550	ret = nfs4_client_recover_expired_lease(clp);
	551	if (ret)
	552	return ret;
	553	}
	554	if (clp->cl_cons_state < NFS_CS_READY)
	555	return -EPROTONOSUPPORT;
	556	smp_rmb();
	557	return 0;
	558	}
	559
18aad3d5	560	int nfs4_init_session(struct nfs_client *clp)
73e39aaa	561	{
73e39aaa TM	562	if (!nfs4_has_session(clp))
	563	return 0;
	564
18aad3d5	565	clear_bit(NFS4_SESSION_INITING, &clp->cl_session->session_state);
73e39aaa TM	566	return nfs41_check_session_ready(clp);
	567	}
	568
	569	int nfs4_init_ds_session(struct nfs_client *clp, unsigned long lease_time)
	570	{
	571	struct nfs4_session *session = clp->cl_session;
	572	int ret;
	573
	574	spin_lock(&clp->cl_lock);
	575	if (test_and_clear_bit(NFS4_SESSION_INITING, &session->session_state)) {
	576	/*
	577	* Do not set NFS_CS_CHECK_LEASE_TIME instead set the
	578	* DS lease to be equal to the MDS lease.
	579	*/
	580	clp->cl_lease_time = lease_time;
	581	clp->cl_last_renewal = jiffies;
	582	}
	583	spin_unlock(&clp->cl_lock);
	584
	585	ret = nfs41_check_session_ready(clp);
	586	if (ret)
	587	return ret;
	588	/* Test for the DS role */
	589	if (!is_ds_client(clp))
	590	return -ENODEV;
	591	return 0;
	592	}
	593	EXPORT_SYMBOL_GPL(nfs4_init_ds_session);
	594
9d33059c	595	#endif /* defined(CONFIG_NFS_V4_1) */