1822 lines
45 KiB
C
1822 lines
45 KiB
C
/* $OpenBSD: vfs_bio.c,v 1.213 2024/02/03 18:51:58 beck Exp $ */
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/* $NetBSD: vfs_bio.c,v 1.44 1996/06/11 11:15:36 pk Exp $ */
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/*
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* Copyright (c) 1994 Christopher G. Demetriou
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* Copyright (c) 1982, 1986, 1989, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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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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* @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94
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*/
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/*
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* Some references:
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* Bach: The Design of the UNIX Operating System (Prentice Hall, 1986)
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* Leffler, et al.: The Design and Implementation of the 4.3BSD
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* UNIX Operating System (Addison Welley, 1989)
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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/proc.h>
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#include <sys/buf.h>
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#include <sys/vnode.h>
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#include <sys/mount.h>
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#include <sys/malloc.h>
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#include <sys/pool.h>
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#include <sys/specdev.h>
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#include <sys/tracepoint.h>
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#include <uvm/uvm_extern.h>
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/* XXX Should really be in buf.h, but for uvm_constraint_range.. */
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int buf_realloc_pages(struct buf *, struct uvm_constraint_range *, int);
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struct uvm_constraint_range high_constraint;
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int fliphigh;
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int nobuffers;
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int needbuffer;
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/* private bufcache functions */
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void bufcache_init(void);
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void bufcache_adjust(void);
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struct buf *bufcache_gethighcleanbuf(void);
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struct buf *bufcache_getdmacleanbuf(void);
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/*
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* Buffer pool for I/O buffers.
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*/
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struct pool bufpool;
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struct bufhead bufhead = LIST_HEAD_INITIALIZER(bufhead);
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void buf_put(struct buf *);
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struct buf *bio_doread(struct vnode *, daddr_t, int, int);
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struct buf *buf_get(struct vnode *, daddr_t, size_t);
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void bread_cluster_callback(struct buf *);
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int64_t bufcache_recover_dmapages(int discard, int64_t howmany);
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static struct buf *incore_locked(struct vnode *vp, daddr_t blkno);
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struct bcachestats bcstats; /* counters */
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long lodirtypages; /* dirty page count low water mark */
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long hidirtypages; /* dirty page count high water mark */
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long targetpages; /* target number of pages for cache size */
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long buflowpages; /* smallest size cache allowed */
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long bufhighpages; /* largest size cache allowed */
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long bufbackpages; /* minimum number of pages we shrink when asked to */
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vsize_t bufkvm;
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struct proc *cleanerproc;
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int bd_req; /* Sleep point for cleaner daemon. */
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#define NUM_CACHES 2
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#define DMA_CACHE 0
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struct bufcache cleancache[NUM_CACHES];
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struct bufqueue dirtyqueue;
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void
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buf_put(struct buf *bp)
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{
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splassert(IPL_BIO);
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#ifdef DIAGNOSTIC
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if (bp->b_pobj != NULL)
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KASSERT(bp->b_bufsize > 0);
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if (ISSET(bp->b_flags, B_DELWRI))
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panic("buf_put: releasing dirty buffer");
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if (bp->b_freelist.tqe_next != NOLIST &&
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bp->b_freelist.tqe_next != (void *)-1)
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panic("buf_put: still on the free list");
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if (bp->b_vnbufs.le_next != NOLIST &&
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bp->b_vnbufs.le_next != (void *)-1)
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panic("buf_put: still on the vnode list");
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#endif
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LIST_REMOVE(bp, b_list);
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bcstats.numbufs--;
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if (buf_dealloc_mem(bp) != 0)
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return;
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pool_put(&bufpool, bp);
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}
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/*
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* Initialize buffers and hash links for buffers.
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*/
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void
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bufinit(void)
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{
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u_int64_t dmapages;
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u_int64_t highpages;
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dmapages = uvm_pagecount(&dma_constraint);
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/* take away a guess at how much of this the kernel will consume */
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dmapages -= (atop(physmem) - atop(uvmexp.free));
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/* See if we have memory above the dma accessible region. */
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high_constraint.ucr_low = dma_constraint.ucr_high;
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high_constraint.ucr_high = no_constraint.ucr_high;
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if (high_constraint.ucr_low != high_constraint.ucr_high)
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high_constraint.ucr_low++;
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highpages = uvm_pagecount(&high_constraint);
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/*
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* Do we have any significant amount of high memory above
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* the DMA region? if so enable moving buffers there, if not,
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* don't bother.
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*/
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if (highpages > dmapages / 4)
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fliphigh = 1;
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else
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fliphigh = 0;
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/*
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* If MD code doesn't say otherwise, use up to 10% of DMA'able
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* memory for buffers.
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*/
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if (bufcachepercent == 0)
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bufcachepercent = 10;
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/*
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* XXX these values and their same use in kern_sysctl
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* need to move into buf.h
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*/
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KASSERT(bufcachepercent <= 90);
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KASSERT(bufcachepercent >= 5);
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if (bufpages == 0)
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bufpages = dmapages * bufcachepercent / 100;
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if (bufpages < BCACHE_MIN)
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bufpages = BCACHE_MIN;
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KASSERT(bufpages < dmapages);
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bufhighpages = bufpages;
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/*
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* Set the base backoff level for the buffer cache. We will
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* not allow uvm to steal back more than this number of pages.
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*/
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buflowpages = dmapages * 5 / 100;
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if (buflowpages < BCACHE_MIN)
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buflowpages = BCACHE_MIN;
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/*
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* set bufbackpages to 100 pages, or 10 percent of the low water mark
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* if we don't have that many pages.
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*/
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bufbackpages = buflowpages * 10 / 100;
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if (bufbackpages > 100)
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bufbackpages = 100;
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/*
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* If the MD code does not say otherwise, reserve 10% of kva
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* space for mapping buffers.
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*/
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if (bufkvm == 0)
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bufkvm = VM_KERNEL_SPACE_SIZE / 10;
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/*
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* Don't use more than twice the amount of bufpages for mappings.
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* It's twice since we map things sparsely.
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*/
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if (bufkvm > bufpages * PAGE_SIZE)
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bufkvm = bufpages * PAGE_SIZE;
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/*
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* Round bufkvm to MAXPHYS because we allocate chunks of va space
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* in MAXPHYS chunks.
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*/
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bufkvm &= ~(MAXPHYS - 1);
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pool_init(&bufpool, sizeof(struct buf), 0, IPL_BIO, 0, "bufpl", NULL);
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bufcache_init();
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/*
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* hmm - bufkvm is an argument because it's static, while
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* bufpages is global because it can change while running.
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*/
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buf_mem_init(bufkvm);
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/*
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* Set the dirty page high water mark to be less than the low
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* water mark for pages in the buffer cache. This ensures we
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* can always back off by throwing away clean pages, and give
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* ourselves a chance to write out the dirty pages eventually.
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*/
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hidirtypages = (buflowpages / 4) * 3;
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lodirtypages = buflowpages / 2;
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/*
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* We are allowed to use up to the reserve.
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*/
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targetpages = bufpages - RESERVE_PAGES;
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}
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/*
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* Change cachepct
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*/
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void
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bufadjust(int newbufpages)
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{
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int s;
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int64_t npages;
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if (newbufpages < buflowpages)
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newbufpages = buflowpages;
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s = splbio();
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bufpages = newbufpages;
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/*
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* We are allowed to use up to the reserve
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*/
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targetpages = bufpages - RESERVE_PAGES;
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npages = bcstats.dmapages - targetpages;
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/*
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* Shrinking the cache happens here only if someone has manually
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* adjusted bufcachepercent - or the pagedaemon has told us
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* to give back memory *now* - so we give it all back.
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*/
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if (bcstats.dmapages > targetpages)
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(void) bufcache_recover_dmapages(0, bcstats.dmapages - targetpages);
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bufcache_adjust();
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/*
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* Wake up the cleaner if we have lots of dirty pages,
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* or if we are getting low on buffer cache kva.
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*/
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if ((UNCLEAN_PAGES >= hidirtypages) ||
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bcstats.kvaslots_avail <= 2 * RESERVE_SLOTS)
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wakeup(&bd_req);
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splx(s);
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}
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/*
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* Make the buffer cache back off from cachepct.
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*/
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int
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bufbackoff(struct uvm_constraint_range *range, long size)
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{
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/*
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* Back off "size" buffer cache pages. Called by the page
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* daemon to consume buffer cache pages rather than scanning.
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*
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* It returns 0 to the pagedaemon to indicate that it has
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* succeeded in freeing enough pages. It returns -1 to
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* indicate that it could not and the pagedaemon should take
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* other measures.
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*
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*/
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long pdelta, oldbufpages;
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/*
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* If we will accept high memory for this backoff
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* try to steal it from the high memory buffer cache.
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*/
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if (range != NULL && range->ucr_high > dma_constraint.ucr_high) {
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struct buf *bp;
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int64_t start = bcstats.numbufpages, recovered = 0;
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int s = splbio();
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while ((recovered < size) &&
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(bp = bufcache_gethighcleanbuf())) {
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bufcache_take(bp);
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if (bp->b_vp) {
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RBT_REMOVE(buf_rb_bufs,
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&bp->b_vp->v_bufs_tree, bp);
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brelvp(bp);
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}
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buf_put(bp);
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recovered = start - bcstats.numbufpages;
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}
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bufcache_adjust();
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splx(s);
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/* If we got enough, return success */
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if (recovered >= size)
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return 0;
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/*
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* If we needed only memory above DMA,
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* return failure
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*/
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if (range->ucr_low > dma_constraint.ucr_high)
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return -1;
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/* Otherwise get the rest from DMA */
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size -= recovered;
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}
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/*
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* XXX Otherwise do the dma memory cache dance. this needs
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* refactoring later to get rid of 'bufpages'
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*/
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/*
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* Back off by at least bufbackpages. If the page daemon gave us
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* a larger size, back off by that much.
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*/
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pdelta = (size > bufbackpages) ? size : bufbackpages;
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if (bufpages <= buflowpages)
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return(-1);
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if (bufpages - pdelta < buflowpages)
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pdelta = bufpages - buflowpages;
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oldbufpages = bufpages;
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bufadjust(bufpages - pdelta);
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if (oldbufpages - bufpages < size)
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return (-1); /* we did not free what we were asked */
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else
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return(0);
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}
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/*
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* Opportunistically flip a buffer into high memory. Will move the buffer
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* if memory is available without sleeping, and return 0, otherwise will
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* fail and return -1 with the buffer unchanged.
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*/
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int
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buf_flip_high(struct buf *bp)
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{
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int ret = -1;
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KASSERT(ISSET(bp->b_flags, B_BC));
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KASSERT(ISSET(bp->b_flags, B_DMA));
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KASSERT(bp->cache == DMA_CACHE);
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KASSERT(fliphigh);
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splassert(IPL_BIO);
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/* Attempt to move the buffer to high memory if we can */
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if (buf_realloc_pages(bp, &high_constraint, UVM_PLA_NOWAIT) == 0) {
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KASSERT(!ISSET(bp->b_flags, B_DMA));
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bcstats.highflips++;
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ret = 0;
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} else
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bcstats.highflops++;
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return ret;
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}
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/*
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* Flip a buffer to dma reachable memory, when we need it there for
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* I/O. This can sleep since it will wait for memory allocation in the
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* DMA reachable area since we have to have the buffer there to proceed.
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*/
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void
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buf_flip_dma(struct buf *bp)
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{
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KASSERT(ISSET(bp->b_flags, B_BC));
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KASSERT(ISSET(bp->b_flags, B_BUSY));
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KASSERT(bp->cache < NUM_CACHES);
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splassert(IPL_BIO);
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if (!ISSET(bp->b_flags, B_DMA)) {
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/* move buf to dma reachable memory */
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(void) buf_realloc_pages(bp, &dma_constraint, UVM_PLA_WAITOK);
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KASSERT(ISSET(bp->b_flags, B_DMA));
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bcstats.dmaflips++;
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}
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if (bp->cache > DMA_CACHE) {
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CLR(bp->b_flags, B_COLD);
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CLR(bp->b_flags, B_WARM);
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bp->cache = DMA_CACHE;
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}
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}
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struct buf *
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bio_doread(struct vnode *vp, daddr_t blkno, int size, int async)
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{
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struct buf *bp;
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struct mount *mp;
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bp = getblk(vp, blkno, size, 0, INFSLP);
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/*
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* If buffer does not have valid data, start a read.
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* Note that if buffer is B_INVAL, getblk() won't return it.
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* Therefore, it's valid if its I/O has completed or been delayed.
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*/
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if (!ISSET(bp->b_flags, (B_DONE | B_DELWRI))) {
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SET(bp->b_flags, B_READ | async);
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bcstats.pendingreads++;
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bcstats.numreads++;
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VOP_STRATEGY(bp->b_vp, bp);
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/* Pay for the read. */
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curproc->p_ru.ru_inblock++; /* XXX */
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} else if (async) {
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brelse(bp);
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}
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mp = vp->v_type == VBLK ? vp->v_specmountpoint : vp->v_mount;
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/*
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* Collect statistics on synchronous and asynchronous reads.
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* Reads from block devices are charged to their associated
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* filesystem (if any).
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*/
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if (mp != NULL) {
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if (async == 0)
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mp->mnt_stat.f_syncreads++;
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else
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mp->mnt_stat.f_asyncreads++;
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}
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return (bp);
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}
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/*
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* Read a disk block.
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* This algorithm described in Bach (p.54).
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*/
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int
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bread(struct vnode *vp, daddr_t blkno, int size, struct buf **bpp)
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{
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struct buf *bp;
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/* Get buffer for block. */
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bp = *bpp = bio_doread(vp, blkno, size, 0);
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/* Wait for the read to complete, and return result. */
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return (biowait(bp));
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}
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/*
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* Read-ahead multiple disk blocks. The first is sync, the rest async.
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* Trivial modification to the breada algorithm presented in Bach (p.55).
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*/
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int
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breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t rablks[],
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int rasizes[], int nrablks, struct buf **bpp)
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{
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struct buf *bp;
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int i;
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bp = *bpp = bio_doread(vp, blkno, size, 0);
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/*
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* For each of the read-ahead blocks, start a read, if necessary.
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*/
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for (i = 0; i < nrablks; i++) {
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/* If it's in the cache, just go on to next one. */
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if (incore(vp, rablks[i]))
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continue;
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/* Get a buffer for the read-ahead block */
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(void) bio_doread(vp, rablks[i], rasizes[i], B_ASYNC);
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}
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/* Otherwise, we had to start a read for it; wait until it's valid. */
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return (biowait(bp));
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}
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|
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/*
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* Called from interrupt context.
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*/
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void
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bread_cluster_callback(struct buf *bp)
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{
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struct buf **xbpp = bp->b_saveaddr;
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int i;
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|
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if (xbpp[1] != NULL) {
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size_t newsize = xbpp[1]->b_bufsize;
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|
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/*
|
|
* Shrink this buffer's mapping to only cover its part of
|
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* the total I/O.
|
|
*/
|
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buf_fix_mapping(bp, newsize);
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bp->b_bcount = newsize;
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}
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|
|
/* Invalidate read-ahead buffers if read short */
|
|
if (bp->b_resid > 0) {
|
|
for (i = 1; xbpp[i] != NULL; i++)
|
|
continue;
|
|
for (i = i - 1; i != 0; i--) {
|
|
if (xbpp[i]->b_bufsize <= bp->b_resid) {
|
|
bp->b_resid -= xbpp[i]->b_bufsize;
|
|
SET(xbpp[i]->b_flags, B_INVAL);
|
|
} else if (bp->b_resid > 0) {
|
|
bp->b_resid = 0;
|
|
SET(xbpp[i]->b_flags, B_INVAL);
|
|
} else
|
|
break;
|
|
}
|
|
}
|
|
|
|
for (i = 1; xbpp[i] != NULL; i++) {
|
|
if (ISSET(bp->b_flags, B_ERROR))
|
|
SET(xbpp[i]->b_flags, B_INVAL | B_ERROR);
|
|
/*
|
|
* Move the pages from the master buffer's uvm object
|
|
* into the individual buffer's uvm objects.
|
|
*/
|
|
struct uvm_object *newobj = &xbpp[i]->b_uobj;
|
|
struct uvm_object *oldobj = &bp->b_uobj;
|
|
int page;
|
|
|
|
uvm_obj_init(newobj, &bufcache_pager, 1);
|
|
for (page = 0; page < atop(xbpp[i]->b_bufsize); page++) {
|
|
struct vm_page *pg = uvm_pagelookup(oldobj,
|
|
xbpp[i]->b_poffs + ptoa(page));
|
|
KASSERT(pg != NULL);
|
|
KASSERT(pg->wire_count == 1);
|
|
uvm_pagerealloc(pg, newobj, xbpp[i]->b_poffs + ptoa(page));
|
|
}
|
|
xbpp[i]->b_pobj = newobj;
|
|
|
|
biodone(xbpp[i]);
|
|
}
|
|
|
|
free(xbpp, M_TEMP, (i + 1) * sizeof(*xbpp));
|
|
|
|
if (ISSET(bp->b_flags, B_ASYNC)) {
|
|
brelse(bp);
|
|
} else {
|
|
CLR(bp->b_flags, B_WANTED);
|
|
wakeup(bp);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Read-ahead multiple disk blocks, but make sure only one (big) I/O
|
|
* request is sent to the disk.
|
|
* XXX This should probably be dropped and breadn should instead be optimized
|
|
* XXX to do fewer I/O requests.
|
|
*/
|
|
int
|
|
bread_cluster(struct vnode *vp, daddr_t blkno, int size, struct buf **rbpp)
|
|
{
|
|
struct buf *bp, **xbpp;
|
|
int howmany, maxra, i, inc;
|
|
daddr_t sblkno;
|
|
|
|
*rbpp = bio_doread(vp, blkno, size, 0);
|
|
|
|
/*
|
|
* If the buffer is in the cache skip any I/O operation.
|
|
*/
|
|
if (ISSET((*rbpp)->b_flags, B_CACHE))
|
|
goto out;
|
|
|
|
if (size != round_page(size))
|
|
goto out;
|
|
|
|
if (VOP_BMAP(vp, blkno + 1, NULL, &sblkno, &maxra))
|
|
goto out;
|
|
|
|
maxra++;
|
|
if (sblkno == -1 || maxra < 2)
|
|
goto out;
|
|
|
|
howmany = MAXPHYS / size;
|
|
if (howmany > maxra)
|
|
howmany = maxra;
|
|
|
|
xbpp = mallocarray(howmany + 1, sizeof(*xbpp), M_TEMP, M_NOWAIT);
|
|
if (xbpp == NULL)
|
|
goto out;
|
|
|
|
for (i = howmany - 1; i >= 0; i--) {
|
|
size_t sz;
|
|
|
|
/*
|
|
* First buffer allocates big enough size to cover what
|
|
* all the other buffers need.
|
|
*/
|
|
sz = i == 0 ? howmany * size : 0;
|
|
|
|
xbpp[i] = buf_get(vp, blkno + i + 1, sz);
|
|
if (xbpp[i] == NULL) {
|
|
for (++i; i < howmany; i++) {
|
|
SET(xbpp[i]->b_flags, B_INVAL);
|
|
brelse(xbpp[i]);
|
|
}
|
|
free(xbpp, M_TEMP, (howmany + 1) * sizeof(*xbpp));
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
bp = xbpp[0];
|
|
|
|
xbpp[howmany] = NULL;
|
|
|
|
inc = btodb(size);
|
|
|
|
for (i = 1; i < howmany; i++) {
|
|
bcstats.pendingreads++;
|
|
bcstats.numreads++;
|
|
/*
|
|
* We set B_DMA here because bp above will be B_DMA,
|
|
* and we are playing buffer slice-n-dice games from
|
|
* the memory allocated in bp.
|
|
*/
|
|
SET(xbpp[i]->b_flags, B_DMA | B_READ | B_ASYNC);
|
|
xbpp[i]->b_blkno = sblkno + (i * inc);
|
|
xbpp[i]->b_bufsize = xbpp[i]->b_bcount = size;
|
|
xbpp[i]->b_data = NULL;
|
|
xbpp[i]->b_pobj = bp->b_pobj;
|
|
xbpp[i]->b_poffs = bp->b_poffs + (i * size);
|
|
}
|
|
|
|
KASSERT(bp->b_lblkno == blkno + 1);
|
|
KASSERT(bp->b_vp == vp);
|
|
|
|
bp->b_blkno = sblkno;
|
|
SET(bp->b_flags, B_READ | B_ASYNC | B_CALL);
|
|
|
|
bp->b_saveaddr = (void *)xbpp;
|
|
bp->b_iodone = bread_cluster_callback;
|
|
|
|
bcstats.pendingreads++;
|
|
bcstats.numreads++;
|
|
VOP_STRATEGY(bp->b_vp, bp);
|
|
curproc->p_ru.ru_inblock++;
|
|
|
|
out:
|
|
return (biowait(*rbpp));
|
|
}
|
|
|
|
/*
|
|
* Block write. Described in Bach (p.56)
|
|
*/
|
|
int
|
|
bwrite(struct buf *bp)
|
|
{
|
|
int rv, async, wasdelayed, s;
|
|
struct vnode *vp;
|
|
struct mount *mp;
|
|
|
|
vp = bp->b_vp;
|
|
if (vp != NULL)
|
|
mp = vp->v_type == VBLK? vp->v_specmountpoint : vp->v_mount;
|
|
else
|
|
mp = NULL;
|
|
|
|
/*
|
|
* Remember buffer type, to switch on it later. If the write was
|
|
* synchronous, but the file system was mounted with MNT_ASYNC,
|
|
* convert it to a delayed write.
|
|
* XXX note that this relies on delayed tape writes being converted
|
|
* to async, not sync writes (which is safe, but ugly).
|
|
*/
|
|
async = ISSET(bp->b_flags, B_ASYNC);
|
|
if (!async && mp && ISSET(mp->mnt_flag, MNT_ASYNC)) {
|
|
/*
|
|
* Don't convert writes from VND on async filesystems
|
|
* that already have delayed writes in the upper layer.
|
|
*/
|
|
if (!ISSET(bp->b_flags, B_NOCACHE)) {
|
|
bdwrite(bp);
|
|
return (0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Collect statistics on synchronous and asynchronous writes.
|
|
* Writes to block devices are charged to their associated
|
|
* filesystem (if any).
|
|
*/
|
|
if (mp != NULL) {
|
|
if (async)
|
|
mp->mnt_stat.f_asyncwrites++;
|
|
else
|
|
mp->mnt_stat.f_syncwrites++;
|
|
}
|
|
bcstats.pendingwrites++;
|
|
bcstats.numwrites++;
|
|
|
|
wasdelayed = ISSET(bp->b_flags, B_DELWRI);
|
|
CLR(bp->b_flags, (B_READ | B_DONE | B_ERROR | B_DELWRI));
|
|
|
|
s = splbio();
|
|
|
|
/*
|
|
* If not synchronous, pay for the I/O operation and make
|
|
* sure the buf is on the correct vnode queue. We have
|
|
* to do this now, because if we don't, the vnode may not
|
|
* be properly notified that its I/O has completed.
|
|
*/
|
|
if (wasdelayed) {
|
|
reassignbuf(bp);
|
|
} else
|
|
curproc->p_ru.ru_oublock++;
|
|
|
|
|
|
/* Initiate disk write. Make sure the appropriate party is charged. */
|
|
bp->b_vp->v_numoutput++;
|
|
buf_flip_dma(bp);
|
|
SET(bp->b_flags, B_WRITEINPROG);
|
|
splx(s);
|
|
VOP_STRATEGY(bp->b_vp, bp);
|
|
|
|
/*
|
|
* If the queue is above the high water mark, wait till
|
|
* the number of outstanding write bufs drops below the low
|
|
* water mark.
|
|
*/
|
|
if (bp->b_bq)
|
|
bufq_wait(bp->b_bq);
|
|
|
|
if (async)
|
|
return (0);
|
|
|
|
/*
|
|
* If I/O was synchronous, wait for it to complete.
|
|
*/
|
|
rv = biowait(bp);
|
|
|
|
/* Release the buffer. */
|
|
brelse(bp);
|
|
|
|
return (rv);
|
|
}
|
|
|
|
|
|
/*
|
|
* Delayed write.
|
|
*
|
|
* The buffer is marked dirty, but is not queued for I/O.
|
|
* This routine should be used when the buffer is expected
|
|
* to be modified again soon, typically a small write that
|
|
* partially fills a buffer.
|
|
*
|
|
* NB: magnetic tapes cannot be delayed; they must be
|
|
* written in the order that the writes are requested.
|
|
*
|
|
* Described in Leffler, et al. (pp. 208-213).
|
|
*/
|
|
void
|
|
bdwrite(struct buf *bp)
|
|
{
|
|
int s;
|
|
|
|
/*
|
|
* If the block hasn't been seen before:
|
|
* (1) Mark it as having been seen,
|
|
* (2) Charge for the write.
|
|
* (3) Make sure it's on its vnode's correct block list,
|
|
* (4) If a buffer is rewritten, move it to end of dirty list
|
|
*/
|
|
if (!ISSET(bp->b_flags, B_DELWRI)) {
|
|
SET(bp->b_flags, B_DELWRI);
|
|
s = splbio();
|
|
buf_flip_dma(bp);
|
|
reassignbuf(bp);
|
|
splx(s);
|
|
curproc->p_ru.ru_oublock++; /* XXX */
|
|
}
|
|
|
|
/* The "write" is done, so mark and release the buffer. */
|
|
CLR(bp->b_flags, B_NEEDCOMMIT);
|
|
CLR(bp->b_flags, B_NOCACHE); /* Must cache delayed writes */
|
|
SET(bp->b_flags, B_DONE);
|
|
brelse(bp);
|
|
}
|
|
|
|
/*
|
|
* Asynchronous block write; just an asynchronous bwrite().
|
|
*/
|
|
void
|
|
bawrite(struct buf *bp)
|
|
{
|
|
|
|
SET(bp->b_flags, B_ASYNC);
|
|
VOP_BWRITE(bp);
|
|
}
|
|
|
|
/*
|
|
* Must be called at splbio()
|
|
*/
|
|
void
|
|
buf_dirty(struct buf *bp)
|
|
{
|
|
splassert(IPL_BIO);
|
|
|
|
#ifdef DIAGNOSTIC
|
|
if (!ISSET(bp->b_flags, B_BUSY))
|
|
panic("Trying to dirty buffer on freelist!");
|
|
#endif
|
|
|
|
if (ISSET(bp->b_flags, B_DELWRI) == 0) {
|
|
SET(bp->b_flags, B_DELWRI);
|
|
buf_flip_dma(bp);
|
|
reassignbuf(bp);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Must be called at splbio()
|
|
*/
|
|
void
|
|
buf_undirty(struct buf *bp)
|
|
{
|
|
splassert(IPL_BIO);
|
|
|
|
#ifdef DIAGNOSTIC
|
|
if (!ISSET(bp->b_flags, B_BUSY))
|
|
panic("Trying to undirty buffer on freelist!");
|
|
#endif
|
|
if (ISSET(bp->b_flags, B_DELWRI)) {
|
|
CLR(bp->b_flags, B_DELWRI);
|
|
reassignbuf(bp);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Release a buffer on to the free lists.
|
|
* Described in Bach (p. 46).
|
|
*/
|
|
void
|
|
brelse(struct buf *bp)
|
|
{
|
|
int s;
|
|
|
|
s = splbio();
|
|
|
|
if (bp->b_data != NULL)
|
|
KASSERT(bp->b_bufsize > 0);
|
|
|
|
/*
|
|
* Determine which queue the buffer should be on, then put it there.
|
|
*/
|
|
|
|
/* If it's not cacheable, or an error, mark it invalid. */
|
|
if (ISSET(bp->b_flags, (B_NOCACHE|B_ERROR)))
|
|
SET(bp->b_flags, B_INVAL);
|
|
/* If it's a write error, also mark the vnode as damaged. */
|
|
if (ISSET(bp->b_flags, B_ERROR) && !ISSET(bp->b_flags, B_READ)) {
|
|
if (bp->b_vp && bp->b_vp->v_type == VREG)
|
|
SET(bp->b_vp->v_bioflag, VBIOERROR);
|
|
}
|
|
|
|
if (ISSET(bp->b_flags, B_INVAL)) {
|
|
/*
|
|
* If the buffer is invalid, free it now rather than leaving
|
|
* it in a queue and wasting memory.
|
|
*/
|
|
if (ISSET(bp->b_flags, B_DELWRI)) {
|
|
CLR(bp->b_flags, B_DELWRI);
|
|
}
|
|
|
|
if (bp->b_vp) {
|
|
RBT_REMOVE(buf_rb_bufs, &bp->b_vp->v_bufs_tree, bp);
|
|
brelvp(bp);
|
|
}
|
|
bp->b_vp = NULL;
|
|
|
|
/*
|
|
* Wake up any processes waiting for _this_ buffer to
|
|
* become free. They are not allowed to grab it
|
|
* since it will be freed. But the only sleeper is
|
|
* getblk and it will restart the operation after
|
|
* sleep.
|
|
*/
|
|
if (ISSET(bp->b_flags, B_WANTED)) {
|
|
CLR(bp->b_flags, B_WANTED);
|
|
wakeup(bp);
|
|
}
|
|
buf_put(bp);
|
|
} else {
|
|
/*
|
|
* It has valid data. Put it on the end of the appropriate
|
|
* queue, so that it'll stick around for as long as possible.
|
|
*/
|
|
bufcache_release(bp);
|
|
|
|
/* Unlock the buffer. */
|
|
CLR(bp->b_flags, (B_AGE | B_ASYNC | B_NOCACHE | B_DEFERRED));
|
|
buf_release(bp);
|
|
|
|
/* Wake up any processes waiting for _this_ buffer to
|
|
* become free. */
|
|
if (ISSET(bp->b_flags, B_WANTED)) {
|
|
CLR(bp->b_flags, B_WANTED);
|
|
wakeup(bp);
|
|
}
|
|
|
|
if (bcstats.dmapages > targetpages)
|
|
(void) bufcache_recover_dmapages(0,
|
|
bcstats.dmapages - targetpages);
|
|
bufcache_adjust();
|
|
}
|
|
|
|
/* Wake up syncer and cleaner processes waiting for buffers. */
|
|
if (nobuffers) {
|
|
nobuffers = 0;
|
|
wakeup(&nobuffers);
|
|
}
|
|
|
|
/* Wake up any processes waiting for any buffer to become free. */
|
|
if (needbuffer && bcstats.dmapages < targetpages &&
|
|
bcstats.kvaslots_avail > RESERVE_SLOTS) {
|
|
needbuffer = 0;
|
|
wakeup(&needbuffer);
|
|
}
|
|
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* Determine if a block is in the cache. Just look on what would be its hash
|
|
* chain. If it's there, return a pointer to it, unless it's marked invalid.
|
|
*/
|
|
static struct buf *
|
|
incore_locked(struct vnode *vp, daddr_t blkno)
|
|
{
|
|
struct buf *bp;
|
|
struct buf b;
|
|
|
|
splassert(IPL_BIO);
|
|
|
|
/* Search buf lookup tree */
|
|
b.b_lblkno = blkno;
|
|
bp = RBT_FIND(buf_rb_bufs, &vp->v_bufs_tree, &b);
|
|
if (bp != NULL && ISSET(bp->b_flags, B_INVAL))
|
|
bp = NULL;
|
|
|
|
return (bp);
|
|
}
|
|
struct buf *
|
|
incore(struct vnode *vp, daddr_t blkno)
|
|
{
|
|
struct buf *bp;
|
|
int s;
|
|
|
|
s = splbio();
|
|
bp = incore_locked(vp, blkno);
|
|
splx(s);
|
|
|
|
return (bp);
|
|
}
|
|
|
|
/*
|
|
* Get a block of requested size that is associated with
|
|
* a given vnode and block offset. If it is found in the
|
|
* block cache, mark it as having been found, make it busy
|
|
* and return it. Otherwise, return an empty block of the
|
|
* correct size. It is up to the caller to ensure that the
|
|
* cached blocks be of the correct size.
|
|
*/
|
|
struct buf *
|
|
getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag,
|
|
uint64_t slptimeo)
|
|
{
|
|
struct buf *bp;
|
|
struct buf b;
|
|
int s, error;
|
|
|
|
/*
|
|
* XXX
|
|
* The following is an inlined version of 'incore()', but with
|
|
* the 'invalid' test moved to after the 'busy' test. It's
|
|
* necessary because there are some cases in which the NFS
|
|
* code sets B_INVAL prior to writing data to the server, but
|
|
* in which the buffers actually contain valid data. In this
|
|
* case, we can't allow the system to allocate a new buffer for
|
|
* the block until the write is finished.
|
|
*/
|
|
start:
|
|
s = splbio();
|
|
b.b_lblkno = blkno;
|
|
bp = RBT_FIND(buf_rb_bufs, &vp->v_bufs_tree, &b);
|
|
if (bp != NULL) {
|
|
if (ISSET(bp->b_flags, B_BUSY)) {
|
|
SET(bp->b_flags, B_WANTED);
|
|
error = tsleep_nsec(bp, slpflag | (PRIBIO + 1),
|
|
"getblk", slptimeo);
|
|
splx(s);
|
|
if (error)
|
|
return (NULL);
|
|
goto start;
|
|
}
|
|
|
|
if (!ISSET(bp->b_flags, B_INVAL)) {
|
|
bcstats.cachehits++;
|
|
SET(bp->b_flags, B_CACHE);
|
|
bufcache_take(bp);
|
|
buf_acquire(bp);
|
|
splx(s);
|
|
return (bp);
|
|
}
|
|
}
|
|
splx(s);
|
|
|
|
if ((bp = buf_get(vp, blkno, size)) == NULL)
|
|
goto start;
|
|
|
|
return (bp);
|
|
}
|
|
|
|
/*
|
|
* Get an empty, disassociated buffer of given size.
|
|
*/
|
|
struct buf *
|
|
geteblk(size_t size)
|
|
{
|
|
struct buf *bp;
|
|
|
|
while ((bp = buf_get(NULL, 0, size)) == NULL)
|
|
continue;
|
|
|
|
return (bp);
|
|
}
|
|
|
|
/*
|
|
* Allocate a buffer.
|
|
* If vp is given, put it into the buffer cache for that vnode.
|
|
* If size != 0, allocate memory and call buf_map().
|
|
* If there is already a buffer for the given vnode/blkno, return NULL.
|
|
*/
|
|
struct buf *
|
|
buf_get(struct vnode *vp, daddr_t blkno, size_t size)
|
|
{
|
|
struct buf *bp;
|
|
int poolwait = size == 0 ? PR_NOWAIT : PR_WAITOK;
|
|
int npages;
|
|
int s;
|
|
|
|
s = splbio();
|
|
if (size) {
|
|
/*
|
|
* Wake up the cleaner if we have lots of dirty pages,
|
|
* or if we are getting low on buffer cache kva.
|
|
*/
|
|
if (UNCLEAN_PAGES >= hidirtypages ||
|
|
bcstats.kvaslots_avail <= 2 * RESERVE_SLOTS)
|
|
wakeup(&bd_req);
|
|
|
|
npages = atop(round_page(size));
|
|
|
|
/*
|
|
* if our cache has been previously shrunk,
|
|
* allow it to grow again with use up to
|
|
* bufhighpages (cachepercent)
|
|
*/
|
|
if (bufpages < bufhighpages)
|
|
bufadjust(bufhighpages);
|
|
|
|
/*
|
|
* If we would go over the page target with our
|
|
* new allocation, free enough buffers first
|
|
* to stay at the target with our new allocation.
|
|
*/
|
|
if (bcstats.dmapages + npages > targetpages) {
|
|
(void) bufcache_recover_dmapages(0, npages);
|
|
bufcache_adjust();
|
|
}
|
|
|
|
/*
|
|
* If we get here, we tried to free the world down
|
|
* above, and couldn't get down - Wake the cleaner
|
|
* and wait for it to push some buffers out.
|
|
*/
|
|
if ((bcstats.dmapages + npages > targetpages ||
|
|
bcstats.kvaslots_avail <= RESERVE_SLOTS) &&
|
|
curproc != syncerproc && curproc != cleanerproc) {
|
|
wakeup(&bd_req);
|
|
needbuffer++;
|
|
tsleep_nsec(&needbuffer, PRIBIO, "needbuffer", INFSLP);
|
|
splx(s);
|
|
return (NULL);
|
|
}
|
|
if (bcstats.dmapages + npages > bufpages) {
|
|
/* cleaner or syncer */
|
|
nobuffers = 1;
|
|
tsleep_nsec(&nobuffers, PRIBIO, "nobuffers", INFSLP);
|
|
splx(s);
|
|
return (NULL);
|
|
}
|
|
}
|
|
|
|
bp = pool_get(&bufpool, poolwait|PR_ZERO);
|
|
|
|
if (bp == NULL) {
|
|
splx(s);
|
|
return (NULL);
|
|
}
|
|
|
|
bp->b_freelist.tqe_next = NOLIST;
|
|
bp->b_dev = NODEV;
|
|
bp->b_bcount = size;
|
|
|
|
buf_acquire_nomap(bp);
|
|
|
|
if (vp != NULL) {
|
|
/*
|
|
* We insert the buffer into the hash with B_BUSY set
|
|
* while we allocate pages for it. This way any getblk
|
|
* that happens while we allocate pages will wait for
|
|
* this buffer instead of starting its own buf_get.
|
|
*
|
|
* But first, we check if someone beat us to it.
|
|
*/
|
|
if (incore_locked(vp, blkno)) {
|
|
pool_put(&bufpool, bp);
|
|
splx(s);
|
|
return (NULL);
|
|
}
|
|
|
|
bp->b_blkno = bp->b_lblkno = blkno;
|
|
bgetvp(vp, bp);
|
|
if (RBT_INSERT(buf_rb_bufs, &vp->v_bufs_tree, bp))
|
|
panic("buf_get: dup lblk vp %p bp %p", vp, bp);
|
|
} else {
|
|
bp->b_vnbufs.le_next = NOLIST;
|
|
SET(bp->b_flags, B_INVAL);
|
|
bp->b_vp = NULL;
|
|
}
|
|
|
|
LIST_INSERT_HEAD(&bufhead, bp, b_list);
|
|
bcstats.numbufs++;
|
|
|
|
if (size) {
|
|
buf_alloc_pages(bp, round_page(size));
|
|
KASSERT(ISSET(bp->b_flags, B_DMA));
|
|
buf_map(bp);
|
|
}
|
|
|
|
SET(bp->b_flags, B_BC);
|
|
splx(s);
|
|
|
|
return (bp);
|
|
}
|
|
|
|
/*
|
|
* Buffer cleaning daemon.
|
|
*/
|
|
void
|
|
buf_daemon(void *arg)
|
|
{
|
|
struct buf *bp = NULL;
|
|
int s, pushed = 0;
|
|
|
|
s = splbio();
|
|
for (;;) {
|
|
if (bp == NULL || (pushed >= 16 &&
|
|
UNCLEAN_PAGES < hidirtypages &&
|
|
bcstats.kvaslots_avail > 2 * RESERVE_SLOTS)){
|
|
pushed = 0;
|
|
/*
|
|
* Wake up anyone who was waiting for buffers
|
|
* to be released.
|
|
*/
|
|
if (needbuffer) {
|
|
needbuffer = 0;
|
|
wakeup(&needbuffer);
|
|
}
|
|
tsleep_nsec(&bd_req, PRIBIO - 7, "cleaner", INFSLP);
|
|
}
|
|
|
|
while ((bp = bufcache_getdirtybuf())) {
|
|
TRACEPOINT(vfs, cleaner, bp->b_flags, pushed,
|
|
lodirtypages, hidirtypages);
|
|
|
|
if (UNCLEAN_PAGES < lodirtypages &&
|
|
bcstats.kvaslots_avail > 2 * RESERVE_SLOTS &&
|
|
pushed >= 16)
|
|
break;
|
|
|
|
bufcache_take(bp);
|
|
buf_acquire(bp);
|
|
splx(s);
|
|
|
|
if (ISSET(bp->b_flags, B_INVAL)) {
|
|
brelse(bp);
|
|
s = splbio();
|
|
continue;
|
|
}
|
|
#ifdef DIAGNOSTIC
|
|
if (!ISSET(bp->b_flags, B_DELWRI))
|
|
panic("Clean buffer on dirty queue");
|
|
#endif
|
|
bawrite(bp);
|
|
pushed++;
|
|
|
|
sched_pause(yield);
|
|
|
|
s = splbio();
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Wait for operations on the buffer to complete.
|
|
* When they do, extract and return the I/O's error value.
|
|
*/
|
|
int
|
|
biowait(struct buf *bp)
|
|
{
|
|
int s;
|
|
|
|
KASSERT(!(bp->b_flags & B_ASYNC));
|
|
|
|
s = splbio();
|
|
while (!ISSET(bp->b_flags, B_DONE))
|
|
tsleep_nsec(bp, PRIBIO + 1, "biowait", INFSLP);
|
|
splx(s);
|
|
|
|
/* check for interruption of I/O (e.g. via NFS), then errors. */
|
|
if (ISSET(bp->b_flags, B_EINTR)) {
|
|
CLR(bp->b_flags, B_EINTR);
|
|
return (EINTR);
|
|
}
|
|
|
|
if (ISSET(bp->b_flags, B_ERROR))
|
|
return (bp->b_error ? bp->b_error : EIO);
|
|
else
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Mark I/O complete on a buffer.
|
|
*
|
|
* If a callback has been requested, e.g. the pageout
|
|
* daemon, do so. Otherwise, awaken waiting processes.
|
|
*
|
|
* [ Leffler, et al., says on p.247:
|
|
* "This routine wakes up the blocked process, frees the buffer
|
|
* for an asynchronous write, or, for a request by the pagedaemon
|
|
* process, invokes a procedure specified in the buffer structure" ]
|
|
*
|
|
* In real life, the pagedaemon (or other system processes) wants
|
|
* to do async stuff to, and doesn't want the buffer brelse()'d.
|
|
* (for swap pager, that puts swap buffers on the free lists (!!!),
|
|
* for the vn device, that puts malloc'd buffers on the free lists!)
|
|
*
|
|
* Must be called at splbio().
|
|
*/
|
|
void
|
|
biodone(struct buf *bp)
|
|
{
|
|
splassert(IPL_BIO);
|
|
|
|
if (ISSET(bp->b_flags, B_DONE))
|
|
panic("biodone already");
|
|
SET(bp->b_flags, B_DONE); /* note that it's done */
|
|
|
|
if (bp->b_bq)
|
|
bufq_done(bp->b_bq, bp);
|
|
|
|
if (!ISSET(bp->b_flags, B_READ)) {
|
|
CLR(bp->b_flags, B_WRITEINPROG);
|
|
vwakeup(bp->b_vp);
|
|
}
|
|
if (bcstats.numbufs &&
|
|
(!(ISSET(bp->b_flags, B_RAW) || ISSET(bp->b_flags, B_PHYS)))) {
|
|
if (!ISSET(bp->b_flags, B_READ)) {
|
|
bcstats.pendingwrites--;
|
|
} else
|
|
bcstats.pendingreads--;
|
|
}
|
|
if (ISSET(bp->b_flags, B_CALL)) { /* if necessary, call out */
|
|
CLR(bp->b_flags, B_CALL); /* but note callout done */
|
|
(*bp->b_iodone)(bp);
|
|
} else {
|
|
if (ISSET(bp->b_flags, B_ASYNC)) {/* if async, release it */
|
|
brelse(bp);
|
|
} else { /* or just wakeup the buffer */
|
|
CLR(bp->b_flags, B_WANTED);
|
|
wakeup(bp);
|
|
}
|
|
}
|
|
}
|
|
|
|
#ifdef DDB
|
|
void bcstats_print(int (*)(const char *, ...)
|
|
__attribute__((__format__(__kprintf__,1,2))));
|
|
/*
|
|
* bcstats_print: ddb hook to print interesting buffer cache counters
|
|
*/
|
|
void
|
|
bcstats_print(
|
|
int (*pr)(const char *, ...) __attribute__((__format__(__kprintf__,1,2))))
|
|
{
|
|
(*pr)("Current Buffer Cache status:\n");
|
|
(*pr)("numbufs %lld busymapped %lld, delwri %lld\n",
|
|
bcstats.numbufs, bcstats.busymapped, bcstats.delwribufs);
|
|
(*pr)("kvaslots %lld avail kva slots %lld\n",
|
|
bcstats.kvaslots, bcstats.kvaslots_avail);
|
|
(*pr)("bufpages %lld, dmapages %lld, dirtypages %lld\n",
|
|
bcstats.numbufpages, bcstats.dmapages, bcstats.numdirtypages);
|
|
(*pr)("pendingreads %lld, pendingwrites %lld\n",
|
|
bcstats.pendingreads, bcstats.pendingwrites);
|
|
(*pr)("highflips %lld, highflops %lld, dmaflips %lld\n",
|
|
bcstats.highflips, bcstats.highflops, bcstats.dmaflips);
|
|
}
|
|
#endif
|
|
|
|
void
|
|
buf_adjcnt(struct buf *bp, long ncount)
|
|
{
|
|
KASSERT(ncount <= bp->b_bufsize);
|
|
bp->b_bcount = ncount;
|
|
}
|
|
|
|
/* bufcache freelist code below */
|
|
/*
|
|
* Copyright (c) 2014 Ted Unangst <tedu@openbsd.org>
|
|
*
|
|
* Permission to use, copy, modify, and distribute this software for any
|
|
* purpose with or without fee is hereby granted, provided that the above
|
|
* copyright notice and this permission notice appear in all copies.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
|
|
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
|
|
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
|
|
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
|
|
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
|
|
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
|
|
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
|
*/
|
|
|
|
/*
|
|
* The code below implements a variant of the 2Q buffer cache algorithm by
|
|
* Johnson and Shasha.
|
|
*
|
|
* General Outline
|
|
* We divide the buffer cache into three working sets: current, previous,
|
|
* and long term. Each list is itself LRU and buffers get promoted and moved
|
|
* around between them. A buffer starts its life in the current working set.
|
|
* As time passes and newer buffers push it out, it will turn into the previous
|
|
* working set and is subject to recycling. But if it's accessed again from
|
|
* the previous working set, that's an indication that it's actually in the
|
|
* long term working set, so we promote it there. The separation of current
|
|
* and previous working sets prevents us from promoting a buffer that's only
|
|
* temporarily hot to the long term cache.
|
|
*
|
|
* The objective is to provide scan resistance by making the long term
|
|
* working set ineligible for immediate recycling, even as the current
|
|
* working set is rapidly turned over.
|
|
*
|
|
* Implementation
|
|
* The code below identifies the current, previous, and long term sets as
|
|
* hotqueue, coldqueue, and warmqueue. The hot and warm queues are capped at
|
|
* 1/3 of the total clean pages, after which point they start pushing their
|
|
* oldest buffers into coldqueue.
|
|
* A buf always starts out with neither WARM or COLD flags set (implying HOT).
|
|
* When released, it will be returned to the tail of the hotqueue list.
|
|
* When the hotqueue gets too large, the oldest hot buf will be moved to the
|
|
* coldqueue, with the B_COLD flag set. When a cold buf is released, we set
|
|
* the B_WARM flag and put it onto the warmqueue. Warm bufs are also
|
|
* directly returned to the end of the warmqueue. As with the hotqueue, when
|
|
* the warmqueue grows too large, B_WARM bufs are moved onto the coldqueue.
|
|
*
|
|
* Note that this design does still support large working sets, greater
|
|
* than the cap of hotqueue or warmqueue would imply. The coldqueue is still
|
|
* cached and has no maximum length. The hot and warm queues form a Y feeding
|
|
* into the coldqueue. Moving bufs between queues is constant time, so this
|
|
* design decays to one long warm->cold queue.
|
|
*
|
|
* In the 2Q paper, hotqueue and coldqueue are A1in and A1out. The warmqueue
|
|
* is Am. We always cache pages, as opposed to pointers to pages for A1.
|
|
*
|
|
* This implementation adds support for multiple 2q caches.
|
|
*
|
|
* If we have more than one 2q cache, as bufs fall off the cold queue
|
|
* for recycling, bufs that have been warm before (which retain the
|
|
* B_WARM flag in addition to B_COLD) can be put into the hot queue of
|
|
* a second level 2Q cache. buffers which are only B_COLD are
|
|
* recycled. Bufs falling off the last cache's cold queue are always
|
|
* recycled.
|
|
*
|
|
*/
|
|
|
|
/*
|
|
* this function is called when a hot or warm queue may have exceeded its
|
|
* size limit. it will move a buf to the coldqueue.
|
|
*/
|
|
int chillbufs(struct
|
|
bufcache *cache, struct bufqueue *queue, int64_t *queuepages);
|
|
|
|
void
|
|
bufcache_init(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NUM_CACHES; i++) {
|
|
TAILQ_INIT(&cleancache[i].hotqueue);
|
|
TAILQ_INIT(&cleancache[i].coldqueue);
|
|
TAILQ_INIT(&cleancache[i].warmqueue);
|
|
}
|
|
TAILQ_INIT(&dirtyqueue);
|
|
}
|
|
|
|
/*
|
|
* if the buffer caches have shrunk, we may need to rebalance our queues.
|
|
*/
|
|
void
|
|
bufcache_adjust(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < NUM_CACHES; i++) {
|
|
while (chillbufs(&cleancache[i], &cleancache[i].warmqueue,
|
|
&cleancache[i].warmbufpages) ||
|
|
chillbufs(&cleancache[i], &cleancache[i].hotqueue,
|
|
&cleancache[i].hotbufpages))
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Get a clean buffer from the cache. if "discard" is set do not promote
|
|
* previously warm buffers as normal, because we are tossing everything
|
|
* away such as in a hibernation
|
|
*/
|
|
struct buf *
|
|
bufcache_getcleanbuf(int cachenum, int discard)
|
|
{
|
|
struct buf *bp = NULL;
|
|
struct bufcache *cache = &cleancache[cachenum];
|
|
struct bufqueue * queue;
|
|
|
|
splassert(IPL_BIO);
|
|
|
|
/* try cold queue */
|
|
while ((bp = TAILQ_FIRST(&cache->coldqueue)) ||
|
|
(bp = TAILQ_FIRST(&cache->warmqueue)) ||
|
|
(bp = TAILQ_FIRST(&cache->hotqueue))) {
|
|
int64_t pages = atop(bp->b_bufsize);
|
|
struct bufcache *newcache;
|
|
|
|
if (discard || cachenum >= NUM_CACHES - 1) {
|
|
/* Victim selected, give it up */
|
|
return bp;
|
|
}
|
|
KASSERT(bp->cache == cachenum);
|
|
|
|
/*
|
|
* If this buffer was warm before, move it to
|
|
* the hot queue in the next cache
|
|
*/
|
|
|
|
if (fliphigh) {
|
|
/*
|
|
* If we are in the DMA cache, try to flip the
|
|
* buffer up high to move it on to the other
|
|
* caches. if we can't move the buffer to high
|
|
* memory without sleeping, we give it up and
|
|
* return it rather than fight for more memory
|
|
* against non buffer cache competitors.
|
|
*/
|
|
SET(bp->b_flags, B_BUSY);
|
|
if (bp->cache == 0 && buf_flip_high(bp) == -1) {
|
|
CLR(bp->b_flags, B_BUSY);
|
|
return bp;
|
|
}
|
|
CLR(bp->b_flags, B_BUSY);
|
|
}
|
|
|
|
/* Move the buffer to the hot queue in the next cache */
|
|
if (ISSET(bp->b_flags, B_COLD)) {
|
|
queue = &cache->coldqueue;
|
|
} else if (ISSET(bp->b_flags, B_WARM)) {
|
|
queue = &cache->warmqueue;
|
|
cache->warmbufpages -= pages;
|
|
} else {
|
|
queue = &cache->hotqueue;
|
|
cache->hotbufpages -= pages;
|
|
}
|
|
TAILQ_REMOVE(queue, bp, b_freelist);
|
|
cache->cachepages -= pages;
|
|
CLR(bp->b_flags, B_WARM);
|
|
CLR(bp->b_flags, B_COLD);
|
|
bp->cache++;
|
|
newcache= &cleancache[bp->cache];
|
|
newcache->cachepages += pages;
|
|
newcache->hotbufpages += pages;
|
|
chillbufs(newcache, &newcache->hotqueue,
|
|
&newcache->hotbufpages);
|
|
TAILQ_INSERT_TAIL(&newcache->hotqueue, bp, b_freelist);
|
|
}
|
|
return bp;
|
|
}
|
|
|
|
|
|
void
|
|
discard_buffer(struct buf *bp)
|
|
{
|
|
splassert(IPL_BIO);
|
|
|
|
bufcache_take(bp);
|
|
if (bp->b_vp) {
|
|
RBT_REMOVE(buf_rb_bufs,
|
|
&bp->b_vp->v_bufs_tree, bp);
|
|
brelvp(bp);
|
|
}
|
|
buf_put(bp);
|
|
}
|
|
|
|
int64_t
|
|
bufcache_recover_dmapages(int discard, int64_t howmany)
|
|
{
|
|
struct buf *bp = NULL;
|
|
struct bufcache *cache = &cleancache[DMA_CACHE];
|
|
struct bufqueue * queue;
|
|
int64_t recovered = 0;
|
|
|
|
splassert(IPL_BIO);
|
|
|
|
while ((recovered < howmany) &&
|
|
((bp = TAILQ_FIRST(&cache->coldqueue)) ||
|
|
(bp = TAILQ_FIRST(&cache->warmqueue)) ||
|
|
(bp = TAILQ_FIRST(&cache->hotqueue)))) {
|
|
int64_t pages = atop(bp->b_bufsize);
|
|
struct bufcache *newcache;
|
|
|
|
if (discard || DMA_CACHE >= NUM_CACHES - 1) {
|
|
discard_buffer(bp);
|
|
continue;
|
|
}
|
|
KASSERT(bp->cache == DMA_CACHE);
|
|
|
|
/*
|
|
* If this buffer was warm before, move it to
|
|
* the hot queue in the next cache
|
|
*/
|
|
|
|
/*
|
|
* One way or another, the pages for this
|
|
* buffer are leaving DMA memory
|
|
*/
|
|
recovered += pages;
|
|
|
|
if (!fliphigh) {
|
|
discard_buffer(bp);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* If we are in the DMA cache, try to flip the
|
|
* buffer up high to move it on to the other
|
|
* caches. if we can't move the buffer to high
|
|
* memory without sleeping, we give it up
|
|
* now rather than fight for more memory
|
|
* against non buffer cache competitors.
|
|
*/
|
|
SET(bp->b_flags, B_BUSY);
|
|
if (bp->cache == 0 && buf_flip_high(bp) == -1) {
|
|
CLR(bp->b_flags, B_BUSY);
|
|
discard_buffer(bp);
|
|
continue;
|
|
}
|
|
CLR(bp->b_flags, B_BUSY);
|
|
|
|
/*
|
|
* Move the buffer to the hot queue in the next cache
|
|
*/
|
|
if (ISSET(bp->b_flags, B_COLD)) {
|
|
queue = &cache->coldqueue;
|
|
} else if (ISSET(bp->b_flags, B_WARM)) {
|
|
queue = &cache->warmqueue;
|
|
cache->warmbufpages -= pages;
|
|
} else {
|
|
queue = &cache->hotqueue;
|
|
cache->hotbufpages -= pages;
|
|
}
|
|
TAILQ_REMOVE(queue, bp, b_freelist);
|
|
cache->cachepages -= pages;
|
|
CLR(bp->b_flags, B_WARM);
|
|
CLR(bp->b_flags, B_COLD);
|
|
bp->cache++;
|
|
newcache= &cleancache[bp->cache];
|
|
newcache->cachepages += pages;
|
|
newcache->hotbufpages += pages;
|
|
chillbufs(newcache, &newcache->hotqueue,
|
|
&newcache->hotbufpages);
|
|
TAILQ_INSERT_TAIL(&newcache->hotqueue, bp, b_freelist);
|
|
}
|
|
return recovered;
|
|
}
|
|
|
|
struct buf *
|
|
bufcache_getcleanbuf_range(int start, int end, int discard)
|
|
{
|
|
int i, j = start, q = end;
|
|
struct buf *bp = NULL;
|
|
|
|
/*
|
|
* XXX in theory we could promote warm buffers into a previous queue
|
|
* so in the pathological case of where we go through all the caches
|
|
* without getting a buffer we have to start at the beginning again.
|
|
*/
|
|
while (j <= q) {
|
|
for (i = q; i >= j; i--)
|
|
if ((bp = bufcache_getcleanbuf(i, discard)))
|
|
return (bp);
|
|
j++;
|
|
}
|
|
return bp;
|
|
}
|
|
|
|
struct buf *
|
|
bufcache_gethighcleanbuf(void)
|
|
{
|
|
if (!fliphigh)
|
|
return NULL;
|
|
return bufcache_getcleanbuf_range(DMA_CACHE + 1, NUM_CACHES - 1, 0);
|
|
}
|
|
|
|
|
|
struct buf *
|
|
bufcache_getdmacleanbuf(void)
|
|
{
|
|
if (fliphigh)
|
|
return bufcache_getcleanbuf_range(DMA_CACHE, DMA_CACHE, 0);
|
|
return bufcache_getcleanbuf_range(DMA_CACHE, NUM_CACHES - 1, 0);
|
|
}
|
|
|
|
|
|
struct buf *
|
|
bufcache_getdirtybuf(void)
|
|
{
|
|
return TAILQ_FIRST(&dirtyqueue);
|
|
}
|
|
|
|
void
|
|
bufcache_take(struct buf *bp)
|
|
{
|
|
struct bufqueue *queue;
|
|
int64_t pages;
|
|
|
|
splassert(IPL_BIO);
|
|
KASSERT(ISSET(bp->b_flags, B_BC));
|
|
KASSERT(bp->cache >= DMA_CACHE);
|
|
KASSERT((bp->cache < NUM_CACHES));
|
|
|
|
pages = atop(bp->b_bufsize);
|
|
|
|
TRACEPOINT(vfs, bufcache_take, bp->b_flags, bp->cache, pages);
|
|
|
|
struct bufcache *cache = &cleancache[bp->cache];
|
|
if (!ISSET(bp->b_flags, B_DELWRI)) {
|
|
if (ISSET(bp->b_flags, B_COLD)) {
|
|
queue = &cache->coldqueue;
|
|
} else if (ISSET(bp->b_flags, B_WARM)) {
|
|
queue = &cache->warmqueue;
|
|
cache->warmbufpages -= pages;
|
|
} else {
|
|
queue = &cache->hotqueue;
|
|
cache->hotbufpages -= pages;
|
|
}
|
|
bcstats.numcleanpages -= pages;
|
|
cache->cachepages -= pages;
|
|
} else {
|
|
queue = &dirtyqueue;
|
|
bcstats.numdirtypages -= pages;
|
|
bcstats.delwribufs--;
|
|
}
|
|
TAILQ_REMOVE(queue, bp, b_freelist);
|
|
}
|
|
|
|
/* move buffers from a hot or warm queue to a cold queue in a cache */
|
|
int
|
|
chillbufs(struct bufcache *cache, struct bufqueue *queue, int64_t *queuepages)
|
|
{
|
|
struct buf *bp;
|
|
int64_t limit, pages;
|
|
|
|
/*
|
|
* We limit the hot queue to be small, with a max of 4096 pages.
|
|
* We limit the warm queue to half the cache size.
|
|
*
|
|
* We impose a minimum size of 96 to prevent too much "wobbling".
|
|
*/
|
|
if (queue == &cache->hotqueue)
|
|
limit = min(cache->cachepages / 20, 4096);
|
|
else if (queue == &cache->warmqueue)
|
|
limit = (cache->cachepages / 2);
|
|
else
|
|
panic("chillbufs: invalid queue");
|
|
|
|
if (*queuepages > 96 && *queuepages > limit) {
|
|
bp = TAILQ_FIRST(queue);
|
|
if (!bp)
|
|
panic("inconsistent bufpage counts");
|
|
pages = atop(bp->b_bufsize);
|
|
*queuepages -= pages;
|
|
TAILQ_REMOVE(queue, bp, b_freelist);
|
|
/* we do not clear B_WARM */
|
|
SET(bp->b_flags, B_COLD);
|
|
TAILQ_INSERT_TAIL(&cache->coldqueue, bp, b_freelist);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void
|
|
bufcache_release(struct buf *bp)
|
|
{
|
|
struct bufqueue *queue;
|
|
int64_t pages;
|
|
struct bufcache *cache = &cleancache[bp->cache];
|
|
|
|
KASSERT(ISSET(bp->b_flags, B_BC));
|
|
pages = atop(bp->b_bufsize);
|
|
|
|
TRACEPOINT(vfs, bufcache_rel, bp->b_flags, bp->cache, pages);
|
|
|
|
if (fliphigh) {
|
|
if (ISSET(bp->b_flags, B_DMA) && bp->cache > 0)
|
|
panic("B_DMA buffer release from cache %d",
|
|
bp->cache);
|
|
else if ((!ISSET(bp->b_flags, B_DMA)) && bp->cache == 0)
|
|
panic("Non B_DMA buffer release from cache %d",
|
|
bp->cache);
|
|
}
|
|
|
|
if (!ISSET(bp->b_flags, B_DELWRI)) {
|
|
int64_t *queuepages;
|
|
if (ISSET(bp->b_flags, B_WARM | B_COLD)) {
|
|
SET(bp->b_flags, B_WARM);
|
|
CLR(bp->b_flags, B_COLD);
|
|
queue = &cache->warmqueue;
|
|
queuepages = &cache->warmbufpages;
|
|
} else {
|
|
queue = &cache->hotqueue;
|
|
queuepages = &cache->hotbufpages;
|
|
}
|
|
*queuepages += pages;
|
|
bcstats.numcleanpages += pages;
|
|
cache->cachepages += pages;
|
|
chillbufs(cache, queue, queuepages);
|
|
} else {
|
|
queue = &dirtyqueue;
|
|
bcstats.numdirtypages += pages;
|
|
bcstats.delwribufs++;
|
|
}
|
|
TAILQ_INSERT_TAIL(queue, bp, b_freelist);
|
|
}
|
|
|
|
#ifdef HIBERNATE
|
|
/*
|
|
* Nuke the buffer cache from orbit when hibernating. We do not want to save
|
|
* any clean cache pages to swap and read them back. the original disk files
|
|
* are just as good.
|
|
*/
|
|
void
|
|
hibernate_suspend_bufcache(void)
|
|
{
|
|
struct buf *bp;
|
|
int s;
|
|
|
|
s = splbio();
|
|
/* Chuck away all the cache pages.. discard bufs, do not promote */
|
|
while ((bp = bufcache_getcleanbuf_range(DMA_CACHE, NUM_CACHES - 1, 1))) {
|
|
bufcache_take(bp);
|
|
if (bp->b_vp) {
|
|
RBT_REMOVE(buf_rb_bufs, &bp->b_vp->v_bufs_tree, bp);
|
|
brelvp(bp);
|
|
}
|
|
buf_put(bp);
|
|
}
|
|
splx(s);
|
|
}
|
|
|
|
void
|
|
hibernate_resume_bufcache(void)
|
|
{
|
|
/* XXX Nothing needed here for now */
|
|
}
|
|
#endif /* HIBERNATE */
|