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