/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License, Version 1.0 only

 * (the "License").  You may not use this file except in compliance

 * with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <sys/systm.h>

#include <sys/sdt.h>

#include <rpc/types.h>

#include <rpc/auth.h>

#include <rpc/auth_unix.h>

#include <rpc/auth_des.h>

#include <rpc/svc.h>

#include <rpc/xdr.h>

#include <nfs/nfs4.h>

#include <nfs/nfs_dispatch.h>

#include <nfs/nfs4_drc.h>

/*

 * This is the duplicate request cache for NFSv4

 */

rfs4_drc_t *nfs4_drc = NULL;

/*

 * How long the entry can remain in the cache

 * once it has been sent to the client and not

 * used in a reply (in seconds)

 */

unsigned nfs4_drc_lifetime = 1;

/*

 * The default size of the duplicate request cache

 */

uint32_t nfs4_drc_max = 8 * 1024;

/*

 * The number of buckets we'd like to hash the

 * replies into.. do not change this on the fly.

 */

uint32_t nfs4_drc_hash = 541;

/*

 * Initialize a duplicate request cache.

 */

rfs4_drc_t *

rfs4_init_drc(uint32_t drc_size, uint32_t drc_hash_size, unsigned ttl)

{

	rfs4_drc_t *drc;

	uint32_t   bki;

	ASSERT(drc_size);

	ASSERT(drc_hash_size);

	drc = kmem_alloc(sizeof (rfs4_drc_t), KM_SLEEP);

	drc->max_size = drc_size;

	drc->in_use = 0;

	drc->drc_ttl = ttl;

	mutex_init(&drc->lock, NULL, MUTEX_DEFAULT, NULL);

	drc->dr_hash = drc_hash_size;

	drc->dr_buckets = kmem_alloc(sizeof (list_t)*drc_hash_size, KM_SLEEP);

	for (bki = 0; bki < drc_hash_size; bki++) {

		list_create(&drc->dr_buckets[bki], sizeof (rfs4_dupreq_t),

		    offsetof(rfs4_dupreq_t, dr_bkt_next));

	}

	list_create(&(drc->dr_cache), sizeof (rfs4_dupreq_t),

		    offsetof(rfs4_dupreq_t, dr_next));

	return (drc);

}

/*

 * Destroy a duplicate request cache.

 */

void

rfs4_fini_drc(rfs4_drc_t *drc)

{

	rfs4_dupreq_t *drp, *drp_next;

	ASSERT(drc);

	/* iterate over the dr_cache and free the enties */

	for (drp = list_head(&(drc->dr_cache)); drp != NULL; drp = drp_next) {

		if (drp->dr_state == NFS4_DUP_REPLAY)

			rfs4_compound_free(&(drp->dr_res));

		if (drp->dr_addr.buf != NULL)

			kmem_free(drp->dr_addr.buf, drp->dr_addr.maxlen);

		drp_next = list_next(&(drc->dr_cache), drp);

		kmem_free(drp, sizeof (rfs4_dupreq_t));

	}

	mutex_destroy(&drc->lock);

	kmem_free(drc->dr_buckets,

		sizeof (list_t)*drc->dr_hash);

	kmem_free(drc, sizeof (rfs4_drc_t));

}

/*

 * rfs4_dr_chstate:

 *

 * Change the state of a rfs4_dupreq. If it's not in transition

 * to the FREE state, update the time used and return. If we

 * are moving to the FREE state then we need to clean up the

 * compound results and move the entry to the end of the list.

 */

void

rfs4_dr_chstate(rfs4_dupreq_t *drp, int new_state)

{

	rfs4_drc_t *drc;

	ASSERT(drp);

	ASSERT(drp->drc);

	ASSERT(drp->dr_bkt);

	ASSERT(MUTEX_HELD(&drp->drc->lock));

	drp->dr_state = new_state;

	if (new_state != NFS4_DUP_FREE) {

		gethrestime(&drp->dr_time_used);

		return;

	}

	drc = drp->drc;

	/*

	 * Remove entry from the bucket and

	 * dr_cache list, free compound results.

	 */

	list_remove(drp->dr_bkt, drp);

	list_remove(&(drc->dr_cache), drp);

	rfs4_compound_free(&(drp->dr_res));

}

/*

 * rfs4_alloc_dr:

 *

 * Pick an entry off the tail -- Use if it is

 * marked NFS4_DUP_FREE, or is an entry in the

 * NFS4_DUP_REPLAY state that has timed-out...

 * Otherwise malloc a new one if we have not reached

 * our maximum cache limit.

 *

 * The list should be in time order, so no need

 * to traverse backwards looking for a timed out

 * entry, NFS4_DUP_FREE's are place on the tail.

 */

rfs4_dupreq_t *

rfs4_alloc_dr(rfs4_drc_t *drc)

{

	rfs4_dupreq_t *drp_tail, *drp = NULL;

	ASSERT(drc);

	ASSERT(MUTEX_HELD(&drc->lock));

	if ((drp_tail = list_tail(&drc->dr_cache)) != NULL) {

		switch (drp_tail->dr_state) {

		case NFS4_DUP_FREE:

			list_remove(&(drc->dr_cache), drp_tail);

			DTRACE_PROBE1(nfss__i__drc_freeclaim,

					rfs4_dupreq_t *, drp_tail);

			return (drp_tail);

			/* NOTREACHED */

		case NFS4_DUP_REPLAY:

			if (gethrestime_sec() >

			    drp_tail->dr_time_used.tv_sec+drc->drc_ttl) {

				/* this entry has timedout so grab it. */

				rfs4_dr_chstate(drp_tail, NFS4_DUP_FREE);

				DTRACE_PROBE1(nfss__i__drc_ttlclaim,

					rfs4_dupreq_t *, drp_tail);

				return (drp_tail);

			}

			break;

		}

	}

	/*

	 * Didn't find something to recycle have

	 * we hit the cache limit ?

	 */

	if (drc->in_use >= drc->max_size) {

		DTRACE_PROBE1(nfss__i__drc_full,

			rfs4_drc_t *, drc);

		return (NULL);

	}

	/* nope, so let's malloc a new one */

	drp = kmem_zalloc(sizeof (rfs4_dupreq_t), KM_SLEEP);

	drp->drc = drc;

	drc->in_use++;

	gethrestime(&drp->dr_time_created);

	DTRACE_PROBE1(nfss__i__drc_new, rfs4_dupreq_t *, drp);

	return (drp);

}

/*

 * rfs4_find_dr:

 *

 * Search for an entry in the duplicate request cache by

 * calculating the hash index based on the XID, and examining

 * the entries in the hash bucket. If we find a match stamp the

 * time_used and return. If the entry does not match it could be

 * ready to be freed. Once we have searched the bucket and we

 * have not exhausted the maximum limit for the cache we will

 * allocate a new entry.

 */

int

rfs4_find_dr(struct svc_req *req, rfs4_drc_t *drc, rfs4_dupreq_t **dup)

{

	uint32_t	the_xid;

	list_t		*dr_bkt;

	rfs4_dupreq_t	*drp;

	int		bktdex;

	/*

	 * Get the XID, calculate the bucket and search to

	 * see if we need to replay from the cache.

	 */

	the_xid = req->rq_xprt->xp_xid;

	bktdex = the_xid % drc->dr_hash;

	dr_bkt = (list_t *)

		&(drc->dr_buckets[(the_xid % drc->dr_hash)]);

	DTRACE_PROBE3(nfss__i__drc_bktdex,

			int, bktdex,

			uint32_t, the_xid,

			list_t *, dr_bkt);

	*dup = NULL;

	mutex_enter(&drc->lock);

	/*

	 * Search the bucket for a matching xid and address.

	 */

	for (drp = list_head(dr_bkt); drp != NULL;

		drp = list_next(dr_bkt, drp)) {

		if (drp->dr_xid == the_xid &&

		    drp->dr_addr.len == req->rq_xprt->xp_rtaddr.len &&

		    bcmp((caddr_t)drp->dr_addr.buf,

		    (caddr_t)req->rq_xprt->xp_rtaddr.buf,

		    drp->dr_addr.len) == 0) {

			/*

			 * Found a match so REPLAY the Reply

			 */

			if (drp->dr_state == NFS4_DUP_REPLAY) {

				gethrestime(&drp->dr_time_used);

				mutex_exit(&drc->lock);

				*dup = drp;

				DTRACE_PROBE1(nfss__i__drc_replay,

					rfs4_dupreq_t *, drp);

				return (NFS4_DUP_REPLAY);

			}

			/*

			 * This entry must be in transition, so return

			 * the 'pending' status.

			 */

			mutex_exit(&drc->lock);

			return (NFS4_DUP_PENDING);

		}

		/*

		 * Not a match, but maybe this entry is ready

		 * to be reused.

		 */

		if (drp->dr_state == NFS4_DUP_REPLAY &&

			(gethrestime_sec() >

			drp->dr_time_used.tv_sec+drc->drc_ttl)) {

			rfs4_dr_chstate(drp, NFS4_DUP_FREE);

			list_insert_tail(&(drp->drc->dr_cache), drp);

		}

	}

	drp = rfs4_alloc_dr(drc);

	mutex_exit(&drc->lock);

	if (drp == NULL) {

		return (NFS4_DUP_ERROR);

	}

	/*

	 * Place at the head of the list, init the state

	 * to NEW and clear the time used field.

	 */

	drp->dr_state = NFS4_DUP_NEW;

	drp->dr_time_used.tv_sec = drp->dr_time_used.tv_nsec = 0;

	/*

	 * If needed, resize the address buffer

	 */

	if (drp->dr_addr.maxlen < req->rq_xprt->xp_rtaddr.len) {

		if (drp->dr_addr.buf != NULL)

			kmem_free(drp->dr_addr.buf, drp->dr_addr.maxlen);

		drp->dr_addr.maxlen = req->rq_xprt->xp_rtaddr.len;

		drp->dr_addr.buf = kmem_alloc(drp->dr_addr.maxlen, KM_NOSLEEP);

		if (drp->dr_addr.buf == NULL) {

			/*

			 * If the malloc fails, mark the entry

			 * as free and put on the tail.

			 */

			drp->dr_addr.maxlen = 0;

			drp->dr_state = NFS4_DUP_FREE;

			mutex_enter(&drc->lock);

			list_insert_tail(&(drc->dr_cache), drp);

			mutex_exit(&drc->lock);

			return (NFS4_DUP_ERROR);

		}

	}

	/*

	 * Copy the address.

	 */

	drp->dr_addr.len = req->rq_xprt->xp_rtaddr.len;

	bcopy((caddr_t)req->rq_xprt->xp_rtaddr.buf,

		(caddr_t)drp->dr_addr.buf,

		drp->dr_addr.len);

	drp->dr_xid = the_xid;

	drp->dr_bkt = dr_bkt;

	/*

	 * Insert at the head of the bucket and

	 * the drc lists..

	 */

	mutex_enter(&drc->lock);

	list_insert_head(&drc->dr_cache, drp);

	list_insert_head(dr_bkt, drp);

	mutex_exit(&drc->lock);

	*dup = drp;

	return (NFS4_DUP_NEW);

}

/*

 *

 * This function handles the duplicate request cache,

 * NULL_PROC and COMPOUND procedure calls for NFSv4;

 *

 * Passed into this function are:-

 *

 * 	disp	A pointer to our dispatch table entry

 * 	req	The request to process

 * 	xprt	The server transport handle

 * 	ap	A pointer to the arguments

 *

 *

 * When appropriate this function is responsible for inserting

 * the reply into the duplicate cache or replaying an existing

 * cached reply.

 *

 * dr_stat 	reflects the state of the duplicate request that

 * 		has been inserted into or retrieved from the cache

 *

 * drp		is the duplicate request entry

 *

 */

int

rfs4_dispatch(struct rpcdisp *disp, struct svc_req *req,

		SVCXPRT *xprt, char *ap)

{

	COMPOUND4res res_buf, *rbp;

	COMPOUND4args *cap;

	cred_t 	*cr = NULL;

	int	error = 0;

	int 	dis_flags = 0;

	int 	dr_stat = NFS4_NOT_DUP;

	rfs4_dupreq_t *drp = NULL;

	ASSERT(disp);

	/*

	 * Short circuit the RPC_NULL proc.

	 */

	if (disp->dis_proc == rpc_null) {

		if (!svc_sendreply(xprt, xdr_void, NULL)) {

			return (1);

		}

		return (0);

	}

	/* Only NFSv4 Compounds from this point onward */

	rbp = &res_buf;

	cap = (COMPOUND4args *)ap;

	/*

	 * Figure out the disposition of the whole COMPOUND

	 * and record it's IDEMPOTENTCY.

	 */

	rfs4_compound_flagproc(cap, &dis_flags);

	/*

	 * If NON-IDEMPOTENT then we need to figure out if this

	 * request can be replied from the duplicate cache.

	 *

	 * If this is a new request then we need to insert the

	 * reply into the duplicate cache.

	 */

	if (!(dis_flags & RPC_IDEMPOTENT)) {

		/* look for a replay from the cache or allocate */

		dr_stat = rfs4_find_dr(req, nfs4_drc, &drp);

		switch (dr_stat) {

		case NFS4_DUP_ERROR:

			svcerr_systemerr(xprt);

			return (1);

			/* NOTREACHED */

		case NFS4_DUP_PENDING:

			/*

			 * reply has previously been inserted into the

			 * duplicate cache, however the reply has

			 * not yet been sent via svc_sendreply()

			 */

			return (1);

			/* NOTREACHED */

		case NFS4_DUP_NEW:

			curthread->t_flag |= T_DONTPEND;

			/* NON-IDEMPOTENT proc call */

			rfs4_compound(cap, rbp, NULL, req, cr);

			curthread->t_flag &= ~T_DONTPEND;

			if (curthread->t_flag & T_WOULDBLOCK) {

				curthread->t_flag &= ~T_WOULDBLOCK;

				/*

				 * mark this entry as FREE and plop

				 * on the end of the cache list

				 */

				mutex_enter(&drp->drc->lock);

				rfs4_dr_chstate(drp, NFS4_DUP_FREE);

				list_insert_tail(&(drp->drc->dr_cache), drp);

				mutex_exit(&drp->drc->lock);

				return (1);

			}

			drp->dr_res = res_buf;

			break;

		case NFS4_DUP_REPLAY:

			/* replay from the cache */

			rbp = &(drp->dr_res);

			break;

		}

	} else {

		curthread->t_flag |= T_DONTPEND;

		/* IDEMPOTENT proc call */

		rfs4_compound(cap, rbp, NULL, req, cr);

		curthread->t_flag &= ~T_DONTPEND;

		if (curthread->t_flag & T_WOULDBLOCK) {

			curthread->t_flag &= ~T_WOULDBLOCK;

			return (1);

		}

	}

	/*

	 * Send out the replayed reply or the 'real' one.

	 */

		DTRACE_PROBE2(nfss__e__dispatch_sendfail,

			struct svc_req *, xprt,

			char *, rbp);

		error++;

	}

	/*

	 * If this reply was just inserted into the duplicate cache

	 * mark it as available for replay

	 */

	if (dr_stat == NFS4_DUP_NEW) {

		mutex_enter(&drp->drc->lock);

		rfs4_dr_chstate(drp, NFS4_DUP_REPLAY);

		mutex_exit(&drp->drc->lock);

	} else if (dr_stat == NFS4_NOT_DUP) {

		rfs4_compound_free(rbp);

	}

	return (error);

}