214 lines
6.0 KiB
C
214 lines
6.0 KiB
C
/* $OpenBSD: nfs_aiod.c,v 1.9 2022/01/11 03:13:59 jsg Exp $ */
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/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Rick Macklem at The University of Guelph.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/vnode.h>
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#include <sys/kthread.h>
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#include <sys/rwlock.h>
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#include <sys/signalvar.h>
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#include <sys/queue.h>
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#include <sys/mutex.h>
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#include <nfs/rpcv2.h>
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#include <nfs/nfsproto.h>
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#include <nfs/nfs.h>
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#include <nfs/nfsnode.h>
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#include <nfs/nfs_var.h>
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#include <nfs/nfsmount.h>
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/* The nfs_aiodl_mtx mutex protects the two lists. */
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struct mutex nfs_aiodl_mtx;
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struct nfs_aiodhead nfs_aiods_all;
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struct nfs_aiodhead nfs_aiods_idle;
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/* Current number of "running" aiods. Defaults to NFS_DEFASYNCDAEMON (4). */
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int nfs_numaiods = -1;
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/* Maximum # of buf to queue on an aiod. */
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int nfs_aiodbufqmax;
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/*
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* Asynchronous I/O threads for client nfs.
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* They do read-ahead and write-behind operations on the block I/O cache.
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* Never returns unless it fails or gets killed.
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*/
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void
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nfs_aiod(void *arg)
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{
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struct nfs_aiod *aiod;
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struct nfsmount *nmp;
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struct buf *bp;
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aiod = malloc(sizeof(*aiod), M_TEMP, M_WAITOK|M_ZERO);
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mtx_enter(&nfs_aiodl_mtx);
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LIST_INSERT_HEAD(&nfs_aiods_all, aiod, nad_all);
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LIST_INSERT_HEAD(&nfs_aiods_idle, aiod, nad_idle);
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mtx_leave(&nfs_aiodl_mtx);
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nfs_numaiods++;
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/*
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* Enforce an upper limit on how many bufs we'll queue up for
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* a given aiod. This is arbitrarily chosen to be a quarter of
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* the number of bufs in the system, divided evenly between
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* the running aiods.
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*
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* Since the number of bufs in the system is dynamic, and the
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* aiods are usually started up very early (during boot), the
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* number of buffers available is pretty low, so the limit we
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* enforce is way to low: So, always allow a minimum of 64 bufs.
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* XXX: Footshooting.
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*/
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nfs_aiodbufqmax = max((bcstats.numbufs / 4) / nfs_numaiods, 64);
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loop: /* Loop around until SIGKILL */
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if (aiod->nad_flags & NFSAIOD_WAKEUP) {
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mtx_enter(&nfs_aiodl_mtx);
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LIST_INSERT_HEAD(&nfs_aiods_idle, aiod, nad_idle);
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mtx_leave(&nfs_aiodl_mtx);
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aiod->nad_flags &= ~NFSAIOD_WAKEUP;
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}
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while (1) {
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nmp = aiod->nad_mnt;
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if (nmp) {
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aiod->nad_mnt = NULL;
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break;
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}
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while (!(aiod->nad_flags & NFSAIOD_WAKEUP))
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tsleep_nsec(aiod, PWAIT, "aiodidle", INFSLP);
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/*
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* Wakeup for this aiod happens in one of the following
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* situations:
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* - The thread is being asked to exit by nfs_set_naiod(), or
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* - nfs_asyncio() has found work for this thread on a mount.
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*
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* In the former case, check to see if nfs_asyncio() has just
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* found some work for this thread, and if so, ignore it until
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* later.
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*/
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if (aiod->nad_flags & NFSAIOD_EXIT) {
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if (aiod->nad_mnt == NULL)
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goto out1;
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else
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break;
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}
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}
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while ((bp = TAILQ_FIRST(&nmp->nm_bufq)) != NULL) {
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/* Take one off the front of the list */
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TAILQ_REMOVE(&nmp->nm_bufq, bp, b_freelist);
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nmp->nm_bufqlen--;
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nfs_doio(bp, NULL);
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}
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KASSERT(nmp->nm_naiods > 0);
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nmp->nm_naiods--;
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if (aiod->nad_flags & NFSAIOD_EXIT)
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goto out1;
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goto loop;
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out1:
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free(aiod, M_TEMP, sizeof(*aiod));
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nfs_numaiods--;
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KASSERT(nfs_numaiods >= 0);
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/* Readjust the limit of bufs to queue. See comment above. */
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if (nfs_numaiods > 0)
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nfs_aiodbufqmax = max((bcstats.numbufs / 4) / nfs_numaiods, 64);
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else
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nfs_aiodbufqmax = 0;
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kthread_exit(0);
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}
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int
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nfs_set_naiod(int howmany)
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{
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struct nfs_aiod *aiod;
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int want, error;
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KASSERT(howmany >= 0);
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error = 0;
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if (nfs_numaiods == -1)
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nfs_numaiods = 0;
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want = howmany - nfs_numaiods;
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if (want > 0) {
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/* Add more. */
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want = min(want, NFS_MAXASYNCDAEMON);
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while (want > 0) {
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error = kthread_create(nfs_aiod, NULL, NULL, "nfsaio");
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if (error)
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return (error);
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want--;
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}
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} else if (want < 0) {
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/* Get rid of some. */
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want = -want;
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want = min(want, nfs_numaiods);
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/* Favour idle aiod's. */
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mtx_enter(&nfs_aiodl_mtx);
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while (!LIST_EMPTY(&nfs_aiods_idle) && want > 0) {
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aiod = LIST_FIRST(&nfs_aiods_idle);
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LIST_REMOVE(aiod, nad_idle);
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LIST_REMOVE(aiod, nad_all); /* Yuck. */
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aiod->nad_flags |= NFSAIOD_QUIT;
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wakeup_one(aiod);
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want--;
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}
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while (!LIST_EMPTY(&nfs_aiods_all) && want > 0) {
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aiod = LIST_FIRST(&nfs_aiods_all);
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LIST_REMOVE(aiod, nad_all);
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aiod->nad_flags |= NFSAIOD_QUIT;
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wakeup_one(aiod);
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want--;
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}
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mtx_leave(&nfs_aiodl_mtx);
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}
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/* ignore the want == nfs_numaiods case, since it means no work */
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return (error);
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}
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