3925 lines
103 KiB
C
3925 lines
103 KiB
C
/*-
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* Copyright (c) 2004 Poul-Henning Kamp
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* Copyright (c) 1994,1997 John S. Dyson
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* All rights reserved.
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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/*
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* this file contains a new buffer I/O scheme implementing a coherent
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* VM object and buffer cache scheme. Pains have been taken to make
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* sure that the performance degradation associated with schemes such
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* as this is not realized.
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*
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* Author: John S. Dyson
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* Significant help during the development and debugging phases
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* had been provided by David Greenman, also of the FreeBSD core team.
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*
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* see man buf(9) for more info.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bio.h>
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#include <sys/conf.h>
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#include <sys/buf.h>
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#include <sys/devicestat.h>
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#include <sys/eventhandler.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/mutex.h>
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#include <sys/kernel.h>
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#include <sys/kthread.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/sysctl.h>
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#include <sys/vmmeter.h>
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#include <sys/vnode.h>
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#include <geom/geom.h>
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/vm_kern.h>
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#include <vm/vm_pageout.h>
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#include <vm/vm_page.h>
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#include <vm/vm_object.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_map.h>
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#include "opt_directio.h"
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#include "opt_swap.h"
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static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer");
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struct bio_ops bioops; /* I/O operation notification */
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struct buf_ops buf_ops_bio = {
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.bop_name = "buf_ops_bio",
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.bop_write = bufwrite,
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.bop_strategy = bufstrategy,
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.bop_sync = bufsync,
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};
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/*
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* XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
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* carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
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*/
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struct buf *buf; /* buffer header pool */
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static struct proc *bufdaemonproc;
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static int inmem(struct vnode *vp, daddr_t blkno);
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static void vm_hold_free_pages(struct buf *bp, vm_offset_t from,
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vm_offset_t to);
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static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
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vm_offset_t to);
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static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off,
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int pageno, vm_page_t m);
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static void vfs_clean_pages(struct buf *bp);
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static void vfs_setdirty(struct buf *bp);
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static void vfs_vmio_release(struct buf *bp);
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static void vfs_backgroundwritedone(struct buf *bp);
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static int vfs_bio_clcheck(struct vnode *vp, int size,
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daddr_t lblkno, daddr_t blkno);
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static int flushbufqueues(int flushdeps);
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static void buf_daemon(void);
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void bremfreel(struct buf *bp);
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int vmiodirenable = TRUE;
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SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
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"Use the VM system for directory writes");
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int runningbufspace;
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SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
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"Amount of presently outstanding async buffer io");
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static int bufspace;
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SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
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"KVA memory used for bufs");
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static int maxbufspace;
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SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
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"Maximum allowed value of bufspace (including buf_daemon)");
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static int bufmallocspace;
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SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
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"Amount of malloced memory for buffers");
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static int maxbufmallocspace;
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SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
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"Maximum amount of malloced memory for buffers");
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static int lobufspace;
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SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
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"Minimum amount of buffers we want to have");
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static int hibufspace;
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SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
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"Maximum allowed value of bufspace (excluding buf_daemon)");
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static int bufreusecnt;
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SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
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"Number of times we have reused a buffer");
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static int buffreekvacnt;
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SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
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"Number of times we have freed the KVA space from some buffer");
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static int bufdefragcnt;
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SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
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"Number of times we have had to repeat buffer allocation to defragment");
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static int lorunningspace;
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SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
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"Minimum preferred space used for in-progress I/O");
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static int hirunningspace;
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SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
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"Maximum amount of space to use for in-progress I/O");
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static int dirtybufferflushes;
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SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
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0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
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static int altbufferflushes;
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SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
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0, "Number of fsync flushes to limit dirty buffers");
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static int recursiveflushes;
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SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
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0, "Number of flushes skipped due to being recursive");
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static int numdirtybuffers;
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SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
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"Number of buffers that are dirty (has unwritten changes) at the moment");
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static int lodirtybuffers;
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SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
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"How many buffers we want to have free before bufdaemon can sleep");
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static int hidirtybuffers;
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SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
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"When the number of dirty buffers is considered severe");
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static int dirtybufthresh;
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SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
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0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
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static int numfreebuffers;
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SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
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"Number of free buffers");
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static int lofreebuffers;
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SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
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"XXX Unused");
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static int hifreebuffers;
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SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
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"XXX Complicatedly unused");
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static int getnewbufcalls;
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SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
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"Number of calls to getnewbuf");
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static int getnewbufrestarts;
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SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
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"Number of times getnewbuf has had to restart a buffer aquisition");
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static int dobkgrdwrite = 1;
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SYSCTL_INT(_debug, OID_AUTO, dobkgrdwrite, CTLFLAG_RW, &dobkgrdwrite, 0,
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"Do background writes (honoring the BV_BKGRDWRITE flag)?");
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/*
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* Wakeup point for bufdaemon, as well as indicator of whether it is already
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* active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
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* is idling.
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*/
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static int bd_request;
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/*
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* This lock synchronizes access to bd_request.
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*/
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static struct mtx bdlock;
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/*
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* bogus page -- for I/O to/from partially complete buffers
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* this is a temporary solution to the problem, but it is not
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* really that bad. it would be better to split the buffer
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* for input in the case of buffers partially already in memory,
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* but the code is intricate enough already.
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*/
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vm_page_t bogus_page;
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/*
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* Synchronization (sleep/wakeup) variable for active buffer space requests.
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* Set when wait starts, cleared prior to wakeup().
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* Used in runningbufwakeup() and waitrunningbufspace().
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*/
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static int runningbufreq;
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/*
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* This lock protects the runningbufreq and synchronizes runningbufwakeup and
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* waitrunningbufspace().
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*/
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static struct mtx rbreqlock;
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/*
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* Synchronization (sleep/wakeup) variable for buffer requests.
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* Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
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* by and/or.
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* Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
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* getnewbuf(), and getblk().
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*/
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static int needsbuffer;
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/*
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* Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
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*/
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static struct mtx nblock;
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/*
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* Lock that protects against bwait()/bdone()/B_DONE races.
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*/
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static struct mtx bdonelock;
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/*
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* Definitions for the buffer free lists.
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*/
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#define BUFFER_QUEUES 5 /* number of free buffer queues */
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#define QUEUE_NONE 0 /* on no queue */
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#define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
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#define QUEUE_DIRTY 2 /* B_DELWRI buffers */
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#define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
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#define QUEUE_EMPTY 4 /* empty buffer headers */
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/* Queues for free buffers with various properties */
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static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
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/* Lock for the bufqueues */
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static struct mtx bqlock;
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/*
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* Single global constant for BUF_WMESG, to avoid getting multiple references.
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* buf_wmesg is referred from macros.
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*/
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const char *buf_wmesg = BUF_WMESG;
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#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
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#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
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#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
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#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
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#ifdef DIRECTIO
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extern void ffs_rawread_setup(void);
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#endif /* DIRECTIO */
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/*
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* numdirtywakeup:
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*
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* If someone is blocked due to there being too many dirty buffers,
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* and numdirtybuffers is now reasonable, wake them up.
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*/
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static __inline void
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numdirtywakeup(int level)
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{
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if (numdirtybuffers <= level) {
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mtx_lock(&nblock);
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if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
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needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
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wakeup(&needsbuffer);
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}
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mtx_unlock(&nblock);
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}
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}
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/*
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* bufspacewakeup:
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*
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* Called when buffer space is potentially available for recovery.
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* getnewbuf() will block on this flag when it is unable to free
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* sufficient buffer space. Buffer space becomes recoverable when
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* bp's get placed back in the queues.
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*/
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static __inline void
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bufspacewakeup(void)
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{
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/*
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* If someone is waiting for BUF space, wake them up. Even
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* though we haven't freed the kva space yet, the waiting
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* process will be able to now.
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*/
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mtx_lock(&nblock);
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if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
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needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
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wakeup(&needsbuffer);
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}
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mtx_unlock(&nblock);
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}
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/*
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* runningbufwakeup() - in-progress I/O accounting.
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*
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*/
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static __inline void
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runningbufwakeup(struct buf *bp)
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{
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if (bp->b_runningbufspace) {
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atomic_subtract_int(&runningbufspace, bp->b_runningbufspace);
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bp->b_runningbufspace = 0;
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mtx_lock(&rbreqlock);
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if (runningbufreq && runningbufspace <= lorunningspace) {
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runningbufreq = 0;
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wakeup(&runningbufreq);
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}
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mtx_unlock(&rbreqlock);
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}
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}
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/*
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* bufcountwakeup:
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*
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* Called when a buffer has been added to one of the free queues to
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* account for the buffer and to wakeup anyone waiting for free buffers.
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* This typically occurs when large amounts of metadata are being handled
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* by the buffer cache ( else buffer space runs out first, usually ).
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*/
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static __inline void
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bufcountwakeup(void)
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{
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atomic_add_int(&numfreebuffers, 1);
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mtx_lock(&nblock);
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if (needsbuffer) {
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needsbuffer &= ~VFS_BIO_NEED_ANY;
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if (numfreebuffers >= hifreebuffers)
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needsbuffer &= ~VFS_BIO_NEED_FREE;
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wakeup(&needsbuffer);
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}
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mtx_unlock(&nblock);
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}
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/*
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* waitrunningbufspace()
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*
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* runningbufspace is a measure of the amount of I/O currently
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* running. This routine is used in async-write situations to
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* prevent creating huge backups of pending writes to a device.
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* Only asynchronous writes are governed by this function.
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*
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* Reads will adjust runningbufspace, but will not block based on it.
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* The read load has a side effect of reducing the allowed write load.
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*
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* This does NOT turn an async write into a sync write. It waits
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* for earlier writes to complete and generally returns before the
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* caller's write has reached the device.
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*/
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static __inline void
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waitrunningbufspace(void)
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{
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mtx_lock(&rbreqlock);
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while (runningbufspace > hirunningspace) {
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++runningbufreq;
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msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
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}
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mtx_unlock(&rbreqlock);
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}
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/*
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* vfs_buf_test_cache:
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*
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* Called when a buffer is extended. This function clears the B_CACHE
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* bit if the newly extended portion of the buffer does not contain
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* valid data.
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*/
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static __inline
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void
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vfs_buf_test_cache(struct buf *bp,
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vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
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vm_page_t m)
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{
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GIANT_REQUIRED;
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VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
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if (bp->b_flags & B_CACHE) {
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int base = (foff + off) & PAGE_MASK;
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if (vm_page_is_valid(m, base, size) == 0)
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bp->b_flags &= ~B_CACHE;
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}
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}
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/* Wake up the buffer deamon if necessary */
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static __inline
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void
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bd_wakeup(int dirtybuflevel)
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{
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mtx_lock(&bdlock);
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if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
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bd_request = 1;
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wakeup(&bd_request);
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}
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mtx_unlock(&bdlock);
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}
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|
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/*
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* bd_speedup - speedup the buffer cache flushing code
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*/
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static __inline
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void
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bd_speedup(void)
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{
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bd_wakeup(1);
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}
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|
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/*
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* Calculating buffer cache scaling values and reserve space for buffer
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* headers. This is called during low level kernel initialization and
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* may be called more then once. We CANNOT write to the memory area
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* being reserved at this time.
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*/
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caddr_t
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kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
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{
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/*
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* physmem_est is in pages. Convert it to kilobytes (assumes
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* PAGE_SIZE is >= 1K)
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*/
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physmem_est = physmem_est * (PAGE_SIZE / 1024);
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/*
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* The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
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* For the first 64MB of ram nominally allocate sufficient buffers to
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* cover 1/4 of our ram. Beyond the first 64MB allocate additional
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* buffers to cover 1/20 of our ram over 64MB. When auto-sizing
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* the buffer cache we limit the eventual kva reservation to
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* maxbcache bytes.
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*
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* factor represents the 1/4 x ram conversion.
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*/
|
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if (nbuf == 0) {
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int factor = 4 * BKVASIZE / 1024;
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|
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nbuf = 50;
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if (physmem_est > 4096)
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|
nbuf += min((physmem_est - 4096) / factor,
|
|
65536 / factor);
|
|
if (physmem_est > 65536)
|
|
nbuf += (physmem_est - 65536) * 2 / (factor * 5);
|
|
|
|
if (maxbcache && nbuf > maxbcache / BKVASIZE)
|
|
nbuf = maxbcache / BKVASIZE;
|
|
}
|
|
|
|
#if 0
|
|
/*
|
|
* Do not allow the buffer_map to be more then 1/2 the size of the
|
|
* kernel_map.
|
|
*/
|
|
if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) /
|
|
(BKVASIZE * 2)) {
|
|
nbuf = (kernel_map->max_offset - kernel_map->min_offset) /
|
|
(BKVASIZE * 2);
|
|
printf("Warning: nbufs capped at %d\n", nbuf);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* swbufs are used as temporary holders for I/O, such as paging I/O.
|
|
* We have no less then 16 and no more then 256.
|
|
*/
|
|
nswbuf = max(min(nbuf/4, 256), 16);
|
|
#ifdef NSWBUF_MIN
|
|
if (nswbuf < NSWBUF_MIN)
|
|
nswbuf = NSWBUF_MIN;
|
|
#endif
|
|
#ifdef DIRECTIO
|
|
ffs_rawread_setup();
|
|
#endif
|
|
|
|
/*
|
|
* Reserve space for the buffer cache buffers
|
|
*/
|
|
swbuf = (void *)v;
|
|
v = (caddr_t)(swbuf + nswbuf);
|
|
buf = (void *)v;
|
|
v = (caddr_t)(buf + nbuf);
|
|
|
|
return(v);
|
|
}
|
|
|
|
/* Initialize the buffer subsystem. Called before use of any buffers. */
|
|
void
|
|
bufinit(void)
|
|
{
|
|
struct buf *bp;
|
|
int i;
|
|
|
|
GIANT_REQUIRED;
|
|
|
|
mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
|
|
mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
|
|
mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
|
|
mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
|
|
mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF);
|
|
|
|
/* next, make a null set of free lists */
|
|
for (i = 0; i < BUFFER_QUEUES; i++)
|
|
TAILQ_INIT(&bufqueues[i]);
|
|
|
|
/* finally, initialize each buffer header and stick on empty q */
|
|
for (i = 0; i < nbuf; i++) {
|
|
bp = &buf[i];
|
|
bzero(bp, sizeof *bp);
|
|
bp->b_flags = B_INVAL; /* we're just an empty header */
|
|
bp->b_rcred = NOCRED;
|
|
bp->b_wcred = NOCRED;
|
|
bp->b_qindex = QUEUE_EMPTY;
|
|
bp->b_vflags = 0;
|
|
bp->b_xflags = 0;
|
|
LIST_INIT(&bp->b_dep);
|
|
BUF_LOCKINIT(bp);
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
|
|
}
|
|
|
|
/*
|
|
* maxbufspace is the absolute maximum amount of buffer space we are
|
|
* allowed to reserve in KVM and in real terms. The absolute maximum
|
|
* is nominally used by buf_daemon. hibufspace is the nominal maximum
|
|
* used by most other processes. The differential is required to
|
|
* ensure that buf_daemon is able to run when other processes might
|
|
* be blocked waiting for buffer space.
|
|
*
|
|
* maxbufspace is based on BKVASIZE. Allocating buffers larger then
|
|
* this may result in KVM fragmentation which is not handled optimally
|
|
* by the system.
|
|
*/
|
|
maxbufspace = nbuf * BKVASIZE;
|
|
hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
|
|
lobufspace = hibufspace - MAXBSIZE;
|
|
|
|
lorunningspace = 512 * 1024;
|
|
hirunningspace = 1024 * 1024;
|
|
|
|
/*
|
|
* Limit the amount of malloc memory since it is wired permanently into
|
|
* the kernel space. Even though this is accounted for in the buffer
|
|
* allocation, we don't want the malloced region to grow uncontrolled.
|
|
* The malloc scheme improves memory utilization significantly on average
|
|
* (small) directories.
|
|
*/
|
|
maxbufmallocspace = hibufspace / 20;
|
|
|
|
/*
|
|
* Reduce the chance of a deadlock occuring by limiting the number
|
|
* of delayed-write dirty buffers we allow to stack up.
|
|
*/
|
|
hidirtybuffers = nbuf / 4 + 20;
|
|
dirtybufthresh = hidirtybuffers * 9 / 10;
|
|
numdirtybuffers = 0;
|
|
/*
|
|
* To support extreme low-memory systems, make sure hidirtybuffers cannot
|
|
* eat up all available buffer space. This occurs when our minimum cannot
|
|
* be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
|
|
* BKVASIZE'd (8K) buffers.
|
|
*/
|
|
while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
|
|
hidirtybuffers >>= 1;
|
|
}
|
|
lodirtybuffers = hidirtybuffers / 2;
|
|
|
|
/*
|
|
* Try to keep the number of free buffers in the specified range,
|
|
* and give special processes (e.g. like buf_daemon) access to an
|
|
* emergency reserve.
|
|
*/
|
|
lofreebuffers = nbuf / 18 + 5;
|
|
hifreebuffers = 2 * lofreebuffers;
|
|
numfreebuffers = nbuf;
|
|
|
|
/*
|
|
* Maximum number of async ops initiated per buf_daemon loop. This is
|
|
* somewhat of a hack at the moment, we really need to limit ourselves
|
|
* based on the number of bytes of I/O in-transit that were initiated
|
|
* from buf_daemon.
|
|
*/
|
|
|
|
bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
|
|
VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
|
|
}
|
|
|
|
/*
|
|
* bfreekva() - free the kva allocation for a buffer.
|
|
*
|
|
* Must be called at splbio() or higher as this is the only locking for
|
|
* buffer_map.
|
|
*
|
|
* Since this call frees up buffer space, we call bufspacewakeup().
|
|
*/
|
|
static void
|
|
bfreekva(struct buf *bp)
|
|
{
|
|
|
|
GIANT_REQUIRED;
|
|
|
|
if (bp->b_kvasize) {
|
|
atomic_add_int(&buffreekvacnt, 1);
|
|
atomic_subtract_int(&bufspace, bp->b_kvasize);
|
|
vm_map_delete(buffer_map,
|
|
(vm_offset_t) bp->b_kvabase,
|
|
(vm_offset_t) bp->b_kvabase + bp->b_kvasize
|
|
);
|
|
bp->b_kvasize = 0;
|
|
bufspacewakeup();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* bremfree:
|
|
*
|
|
* Mark the buffer for removal from the appropriate free list in brelse.
|
|
*
|
|
*/
|
|
void
|
|
bremfree(struct buf *bp)
|
|
{
|
|
|
|
KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked."));
|
|
KASSERT((bp->b_flags & B_REMFREE) == 0 && bp->b_qindex != QUEUE_NONE,
|
|
("bremfree: buffer not on a queue."));
|
|
|
|
bp->b_flags |= B_REMFREE;
|
|
/* Fixup numfreebuffers count. */
|
|
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
|
|
atomic_subtract_int(&numfreebuffers, 1);
|
|
}
|
|
|
|
/*
|
|
* bremfreef:
|
|
*
|
|
* Force an immediate removal from a free list. Used only in nfs when
|
|
* it abuses the b_freelist pointer.
|
|
*/
|
|
void
|
|
bremfreef(struct buf *bp)
|
|
{
|
|
mtx_lock(&bqlock);
|
|
bremfreel(bp);
|
|
mtx_unlock(&bqlock);
|
|
}
|
|
|
|
/*
|
|
* bremfreel:
|
|
*
|
|
* Removes a buffer from the free list, must be called with the
|
|
* bqlock held.
|
|
*/
|
|
void
|
|
bremfreel(struct buf *bp)
|
|
{
|
|
int s = splbio();
|
|
|
|
mtx_assert(&bqlock, MA_OWNED);
|
|
|
|
if (bp->b_qindex != QUEUE_NONE) {
|
|
KASSERT(BUF_REFCNT(bp) == 1, ("bremfree: bp %p not locked",bp));
|
|
TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
|
|
bp->b_qindex = QUEUE_NONE;
|
|
} else {
|
|
if (BUF_REFCNT(bp) <= 1)
|
|
panic("bremfree: removing a buffer not on a queue");
|
|
}
|
|
/*
|
|
* If this was a delayed bremfree() we only need to remove the buffer
|
|
* from the queue and return the stats are already done.
|
|
*/
|
|
if (bp->b_flags & B_REMFREE) {
|
|
bp->b_flags &= ~B_REMFREE;
|
|
splx(s);
|
|
return;
|
|
}
|
|
/*
|
|
* Fixup numfreebuffers count. If the buffer is invalid or not
|
|
* delayed-write, the buffer was free and we must decrement
|
|
* numfreebuffers.
|
|
*/
|
|
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
|
|
atomic_subtract_int(&numfreebuffers, 1);
|
|
splx(s);
|
|
}
|
|
|
|
|
|
/*
|
|
* Get a buffer with the specified data. Look in the cache first. We
|
|
* must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
|
|
* is set, the buffer is valid and we do not have to do anything ( see
|
|
* getblk() ). This is really just a special case of breadn().
|
|
*/
|
|
int
|
|
bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
|
|
struct buf **bpp)
|
|
{
|
|
|
|
return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
|
|
}
|
|
|
|
/*
|
|
* Operates like bread, but also starts asynchronous I/O on
|
|
* read-ahead blocks. We must clear BIO_ERROR and B_INVAL prior
|
|
* to initiating I/O . If B_CACHE is set, the buffer is valid
|
|
* and we do not have to do anything.
|
|
*/
|
|
int
|
|
breadn(struct vnode * vp, daddr_t blkno, int size,
|
|
daddr_t * rablkno, int *rabsize,
|
|
int cnt, struct ucred * cred, struct buf **bpp)
|
|
{
|
|
struct buf *bp, *rabp;
|
|
int i;
|
|
int rv = 0, readwait = 0;
|
|
|
|
*bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
|
|
|
|
/* if not found in cache, do some I/O */
|
|
if ((bp->b_flags & B_CACHE) == 0) {
|
|
if (curthread != PCPU_GET(idlethread))
|
|
curthread->td_proc->p_stats->p_ru.ru_inblock++;
|
|
bp->b_iocmd = BIO_READ;
|
|
bp->b_flags &= ~B_INVAL;
|
|
bp->b_ioflags &= ~BIO_ERROR;
|
|
if (bp->b_rcred == NOCRED && cred != NOCRED)
|
|
bp->b_rcred = crhold(cred);
|
|
vfs_busy_pages(bp, 0);
|
|
bp->b_iooffset = dbtob(bp->b_blkno);
|
|
bstrategy(bp);
|
|
++readwait;
|
|
}
|
|
|
|
for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
|
|
if (inmem(vp, *rablkno))
|
|
continue;
|
|
rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
|
|
|
|
if ((rabp->b_flags & B_CACHE) == 0) {
|
|
if (curthread != PCPU_GET(idlethread))
|
|
curthread->td_proc->p_stats->p_ru.ru_inblock++;
|
|
rabp->b_flags |= B_ASYNC;
|
|
rabp->b_flags &= ~B_INVAL;
|
|
rabp->b_ioflags &= ~BIO_ERROR;
|
|
rabp->b_iocmd = BIO_READ;
|
|
if (rabp->b_rcred == NOCRED && cred != NOCRED)
|
|
rabp->b_rcred = crhold(cred);
|
|
vfs_busy_pages(rabp, 0);
|
|
BUF_KERNPROC(rabp);
|
|
rabp->b_iooffset = dbtob(rabp->b_blkno);
|
|
bstrategy(rabp);
|
|
} else {
|
|
brelse(rabp);
|
|
}
|
|
}
|
|
|
|
if (readwait) {
|
|
rv = bufwait(bp);
|
|
}
|
|
return (rv);
|
|
}
|
|
|
|
/*
|
|
* Write, release buffer on completion. (Done by iodone
|
|
* if async). Do not bother writing anything if the buffer
|
|
* is invalid.
|
|
*
|
|
* Note that we set B_CACHE here, indicating that buffer is
|
|
* fully valid and thus cacheable. This is true even of NFS
|
|
* now so we set it generally. This could be set either here
|
|
* or in biodone() since the I/O is synchronous. We put it
|
|
* here.
|
|
*/
|
|
int
|
|
bufwrite(struct buf *bp)
|
|
{
|
|
int oldflags, s;
|
|
struct buf *newbp;
|
|
|
|
if (bp->b_flags & B_INVAL) {
|
|
brelse(bp);
|
|
return (0);
|
|
}
|
|
|
|
oldflags = bp->b_flags;
|
|
|
|
if (BUF_REFCNT(bp) == 0)
|
|
panic("bufwrite: buffer is not busy???");
|
|
s = splbio();
|
|
/*
|
|
* If a background write is already in progress, delay
|
|
* writing this block if it is asynchronous. Otherwise
|
|
* wait for the background write to complete.
|
|
*/
|
|
BO_LOCK(bp->b_bufobj);
|
|
if (bp->b_vflags & BV_BKGRDINPROG) {
|
|
if (bp->b_flags & B_ASYNC) {
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
splx(s);
|
|
bdwrite(bp);
|
|
return (0);
|
|
}
|
|
bp->b_vflags |= BV_BKGRDWAIT;
|
|
msleep(&bp->b_xflags, BO_MTX(bp->b_bufobj), PRIBIO, "bwrbg", 0);
|
|
if (bp->b_vflags & BV_BKGRDINPROG)
|
|
panic("bufwrite: still writing");
|
|
}
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
|
|
/* Mark the buffer clean */
|
|
bundirty(bp);
|
|
|
|
/*
|
|
* If this buffer is marked for background writing and we
|
|
* do not have to wait for it, make a copy and write the
|
|
* copy so as to leave this buffer ready for further use.
|
|
*
|
|
* This optimization eats a lot of memory. If we have a page
|
|
* or buffer shortfall we can't do it.
|
|
*/
|
|
if (dobkgrdwrite && (bp->b_xflags & BX_BKGRDWRITE) &&
|
|
(bp->b_flags & B_ASYNC) &&
|
|
!vm_page_count_severe() &&
|
|
!buf_dirty_count_severe()) {
|
|
KASSERT(bp->b_iodone == NULL,
|
|
("bufwrite: needs chained iodone (%p)", bp->b_iodone));
|
|
|
|
/* get a new block */
|
|
newbp = geteblk(bp->b_bufsize);
|
|
|
|
/*
|
|
* set it to be identical to the old block. We have to
|
|
* set b_lblkno and BKGRDMARKER before calling bgetvp()
|
|
* to avoid confusing the splay tree and gbincore().
|
|
*/
|
|
memcpy(newbp->b_data, bp->b_data, bp->b_bufsize);
|
|
newbp->b_lblkno = bp->b_lblkno;
|
|
newbp->b_xflags |= BX_BKGRDMARKER;
|
|
BO_LOCK(bp->b_bufobj);
|
|
bp->b_vflags |= BV_BKGRDINPROG;
|
|
bgetvp(bp->b_vp, newbp);
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
newbp->b_bufobj = &bp->b_vp->v_bufobj;
|
|
newbp->b_blkno = bp->b_blkno;
|
|
newbp->b_offset = bp->b_offset;
|
|
newbp->b_iodone = vfs_backgroundwritedone;
|
|
newbp->b_flags |= B_ASYNC;
|
|
newbp->b_flags &= ~B_INVAL;
|
|
|
|
/* move over the dependencies */
|
|
if (LIST_FIRST(&bp->b_dep) != NULL)
|
|
buf_movedeps(bp, newbp);
|
|
|
|
/*
|
|
* Initiate write on the copy, release the original to
|
|
* the B_LOCKED queue so that it cannot go away until
|
|
* the background write completes. If not locked it could go
|
|
* away and then be reconstituted while it was being written.
|
|
* If the reconstituted buffer were written, we could end up
|
|
* with two background copies being written at the same time.
|
|
*/
|
|
bqrelse(bp);
|
|
bp = newbp;
|
|
}
|
|
|
|
bp->b_flags &= ~B_DONE;
|
|
bp->b_ioflags &= ~BIO_ERROR;
|
|
bp->b_flags |= B_CACHE;
|
|
bp->b_iocmd = BIO_WRITE;
|
|
|
|
bufobj_wref(bp->b_bufobj);
|
|
vfs_busy_pages(bp, 1);
|
|
|
|
/*
|
|
* Normal bwrites pipeline writes
|
|
*/
|
|
bp->b_runningbufspace = bp->b_bufsize;
|
|
atomic_add_int(&runningbufspace, bp->b_runningbufspace);
|
|
|
|
if (curthread != PCPU_GET(idlethread))
|
|
curthread->td_proc->p_stats->p_ru.ru_oublock++;
|
|
splx(s);
|
|
if (oldflags & B_ASYNC)
|
|
BUF_KERNPROC(bp);
|
|
bp->b_iooffset = dbtob(bp->b_blkno);
|
|
bstrategy(bp);
|
|
|
|
if ((oldflags & B_ASYNC) == 0) {
|
|
int rtval = bufwait(bp);
|
|
brelse(bp);
|
|
return (rtval);
|
|
} else {
|
|
/*
|
|
* don't allow the async write to saturate the I/O
|
|
* system. We will not deadlock here because
|
|
* we are blocking waiting for I/O that is already in-progress
|
|
* to complete. We do not block here if it is the update
|
|
* or syncer daemon trying to clean up as that can lead
|
|
* to deadlock.
|
|
*/
|
|
if (curthread->td_proc != bufdaemonproc &&
|
|
curthread->td_proc != updateproc)
|
|
waitrunningbufspace();
|
|
}
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Complete a background write started from bwrite.
|
|
*/
|
|
static void
|
|
vfs_backgroundwritedone(struct buf *bp)
|
|
{
|
|
struct buf *origbp;
|
|
|
|
/*
|
|
* Find the original buffer that we are writing.
|
|
*/
|
|
BO_LOCK(bp->b_bufobj);
|
|
if ((origbp = gbincore(bp->b_bufobj, bp->b_lblkno)) == NULL)
|
|
panic("backgroundwritedone: lost buffer");
|
|
|
|
/*
|
|
* Clear the BV_BKGRDINPROG flag in the original buffer
|
|
* and awaken it if it is waiting for the write to complete.
|
|
* If BV_BKGRDINPROG is not set in the original buffer it must
|
|
* have been released and re-instantiated - which is not legal.
|
|
*/
|
|
KASSERT((origbp->b_vflags & BV_BKGRDINPROG),
|
|
("backgroundwritedone: lost buffer2"));
|
|
origbp->b_vflags &= ~BV_BKGRDINPROG;
|
|
if (origbp->b_vflags & BV_BKGRDWAIT) {
|
|
origbp->b_vflags &= ~BV_BKGRDWAIT;
|
|
wakeup(&origbp->b_xflags);
|
|
}
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
/*
|
|
* Process dependencies then return any unfinished ones.
|
|
*/
|
|
if (LIST_FIRST(&bp->b_dep) != NULL)
|
|
buf_complete(bp);
|
|
if (LIST_FIRST(&bp->b_dep) != NULL)
|
|
buf_movedeps(bp, origbp);
|
|
|
|
/*
|
|
* This buffer is marked B_NOCACHE, so when it is released
|
|
* by biodone, it will be tossed. We mark it with BIO_READ
|
|
* to avoid biodone doing a second bufobj_wdrop.
|
|
*/
|
|
bp->b_flags |= B_NOCACHE;
|
|
bp->b_iocmd = BIO_READ;
|
|
bp->b_flags &= ~(B_CACHE | B_DONE);
|
|
bp->b_iodone = 0;
|
|
bufdone(bp);
|
|
}
|
|
|
|
/*
|
|
* Delayed write. (Buffer is marked dirty). Do not bother writing
|
|
* anything if the buffer is marked invalid.
|
|
*
|
|
* Note that since the buffer must be completely valid, we can safely
|
|
* set B_CACHE. In fact, we have to set B_CACHE here rather then in
|
|
* biodone() in order to prevent getblk from writing the buffer
|
|
* out synchronously.
|
|
*/
|
|
void
|
|
bdwrite(struct buf *bp)
|
|
{
|
|
struct thread *td = curthread;
|
|
struct vnode *vp;
|
|
struct buf *nbp;
|
|
struct bufobj *bo;
|
|
|
|
GIANT_REQUIRED;
|
|
|
|
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
|
|
KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy"));
|
|
|
|
if (bp->b_flags & B_INVAL) {
|
|
brelse(bp);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* If we have too many dirty buffers, don't create any more.
|
|
* If we are wildly over our limit, then force a complete
|
|
* cleanup. Otherwise, just keep the situation from getting
|
|
* out of control. Note that we have to avoid a recursive
|
|
* disaster and not try to clean up after our own cleanup!
|
|
*/
|
|
vp = bp->b_vp;
|
|
bo = bp->b_bufobj;
|
|
BO_LOCK(bo);
|
|
if (td->td_pflags & TDP_COWINPROGRESS) {
|
|
recursiveflushes++;
|
|
} else if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
|
|
BO_UNLOCK(bo);
|
|
(void) VOP_FSYNC(vp, MNT_NOWAIT, td);
|
|
BO_LOCK(bo);
|
|
altbufferflushes++;
|
|
} else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
|
|
/*
|
|
* Try to find a buffer to flush.
|
|
*/
|
|
TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
|
|
if ((nbp->b_vflags & BV_BKGRDINPROG) ||
|
|
buf_countdeps(nbp, 0) ||
|
|
BUF_LOCK(nbp, LK_EXCLUSIVE | LK_NOWAIT, NULL))
|
|
continue;
|
|
if (bp == nbp)
|
|
panic("bdwrite: found ourselves");
|
|
BO_UNLOCK(bo);
|
|
if (nbp->b_flags & B_CLUSTEROK) {
|
|
vfs_bio_awrite(nbp);
|
|
} else {
|
|
bremfree(nbp);
|
|
bawrite(nbp);
|
|
}
|
|
BO_LOCK(bo);
|
|
dirtybufferflushes++;
|
|
break;
|
|
}
|
|
}
|
|
BO_UNLOCK(bo);
|
|
|
|
bdirty(bp);
|
|
/*
|
|
* Set B_CACHE, indicating that the buffer is fully valid. This is
|
|
* true even of NFS now.
|
|
*/
|
|
bp->b_flags |= B_CACHE;
|
|
|
|
/*
|
|
* This bmap keeps the system from needing to do the bmap later,
|
|
* perhaps when the system is attempting to do a sync. Since it
|
|
* is likely that the indirect block -- or whatever other datastructure
|
|
* that the filesystem needs is still in memory now, it is a good
|
|
* thing to do this. Note also, that if the pageout daemon is
|
|
* requesting a sync -- there might not be enough memory to do
|
|
* the bmap then... So, this is important to do.
|
|
*/
|
|
if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
|
|
VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
|
|
}
|
|
|
|
/*
|
|
* Set the *dirty* buffer range based upon the VM system dirty pages.
|
|
*/
|
|
vfs_setdirty(bp);
|
|
|
|
/*
|
|
* We need to do this here to satisfy the vnode_pager and the
|
|
* pageout daemon, so that it thinks that the pages have been
|
|
* "cleaned". Note that since the pages are in a delayed write
|
|
* buffer -- the VFS layer "will" see that the pages get written
|
|
* out on the next sync, or perhaps the cluster will be completed.
|
|
*/
|
|
vfs_clean_pages(bp);
|
|
bqrelse(bp);
|
|
|
|
/*
|
|
* Wakeup the buffer flushing daemon if we have a lot of dirty
|
|
* buffers (midpoint between our recovery point and our stall
|
|
* point).
|
|
*/
|
|
bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
|
|
|
|
/*
|
|
* note: we cannot initiate I/O from a bdwrite even if we wanted to,
|
|
* due to the softdep code.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* bdirty:
|
|
*
|
|
* Turn buffer into delayed write request. We must clear BIO_READ and
|
|
* B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
|
|
* itself to properly update it in the dirty/clean lists. We mark it
|
|
* B_DONE to ensure that any asynchronization of the buffer properly
|
|
* clears B_DONE ( else a panic will occur later ).
|
|
*
|
|
* bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
|
|
* might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
|
|
* should only be called if the buffer is known-good.
|
|
*
|
|
* Since the buffer is not on a queue, we do not update the numfreebuffers
|
|
* count.
|
|
*
|
|
* Must be called at splbio().
|
|
* The buffer must be on QUEUE_NONE.
|
|
*/
|
|
void
|
|
bdirty(struct buf *bp)
|
|
{
|
|
|
|
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
|
|
KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
|
|
("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
|
|
bp->b_flags &= ~(B_RELBUF);
|
|
bp->b_iocmd = BIO_WRITE;
|
|
|
|
if ((bp->b_flags & B_DELWRI) == 0) {
|
|
bp->b_flags |= B_DONE | B_DELWRI;
|
|
reassignbuf(bp);
|
|
atomic_add_int(&numdirtybuffers, 1);
|
|
bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* bundirty:
|
|
*
|
|
* Clear B_DELWRI for buffer.
|
|
*
|
|
* Since the buffer is not on a queue, we do not update the numfreebuffers
|
|
* count.
|
|
*
|
|
* Must be called at splbio().
|
|
* The buffer must be on QUEUE_NONE.
|
|
*/
|
|
|
|
void
|
|
bundirty(struct buf *bp)
|
|
{
|
|
|
|
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
|
|
KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
|
|
("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
|
|
|
|
if (bp->b_flags & B_DELWRI) {
|
|
bp->b_flags &= ~B_DELWRI;
|
|
reassignbuf(bp);
|
|
atomic_subtract_int(&numdirtybuffers, 1);
|
|
numdirtywakeup(lodirtybuffers);
|
|
}
|
|
/*
|
|
* Since it is now being written, we can clear its deferred write flag.
|
|
*/
|
|
bp->b_flags &= ~B_DEFERRED;
|
|
}
|
|
|
|
/*
|
|
* bawrite:
|
|
*
|
|
* Asynchronous write. Start output on a buffer, but do not wait for
|
|
* it to complete. The buffer is released when the output completes.
|
|
*
|
|
* bwrite() ( or the VOP routine anyway ) is responsible for handling
|
|
* B_INVAL buffers. Not us.
|
|
*/
|
|
void
|
|
bawrite(struct buf *bp)
|
|
{
|
|
|
|
bp->b_flags |= B_ASYNC;
|
|
(void) bwrite(bp);
|
|
}
|
|
|
|
/*
|
|
* bwillwrite:
|
|
*
|
|
* Called prior to the locking of any vnodes when we are expecting to
|
|
* write. We do not want to starve the buffer cache with too many
|
|
* dirty buffers so we block here. By blocking prior to the locking
|
|
* of any vnodes we attempt to avoid the situation where a locked vnode
|
|
* prevents the various system daemons from flushing related buffers.
|
|
*/
|
|
|
|
void
|
|
bwillwrite(void)
|
|
{
|
|
|
|
if (numdirtybuffers >= hidirtybuffers) {
|
|
int s;
|
|
|
|
mtx_lock(&Giant);
|
|
s = splbio();
|
|
mtx_lock(&nblock);
|
|
while (numdirtybuffers >= hidirtybuffers) {
|
|
bd_wakeup(1);
|
|
needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
|
|
msleep(&needsbuffer, &nblock,
|
|
(PRIBIO + 4), "flswai", 0);
|
|
}
|
|
splx(s);
|
|
mtx_unlock(&nblock);
|
|
mtx_unlock(&Giant);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Return true if we have too many dirty buffers.
|
|
*/
|
|
int
|
|
buf_dirty_count_severe(void)
|
|
{
|
|
|
|
return(numdirtybuffers >= hidirtybuffers);
|
|
}
|
|
|
|
/*
|
|
* brelse:
|
|
*
|
|
* Release a busy buffer and, if requested, free its resources. The
|
|
* buffer will be stashed in the appropriate bufqueue[] allowing it
|
|
* to be accessed later as a cache entity or reused for other purposes.
|
|
*/
|
|
void
|
|
brelse(struct buf *bp)
|
|
{
|
|
int s;
|
|
|
|
GIANT_REQUIRED;
|
|
|
|
KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
|
|
("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
|
|
|
|
s = splbio();
|
|
|
|
if (bp->b_iocmd == BIO_WRITE &&
|
|
(bp->b_ioflags & BIO_ERROR) &&
|
|
!(bp->b_flags & B_INVAL)) {
|
|
/*
|
|
* Failed write, redirty. Must clear BIO_ERROR to prevent
|
|
* pages from being scrapped. If B_INVAL is set then
|
|
* this case is not run and the next case is run to
|
|
* destroy the buffer. B_INVAL can occur if the buffer
|
|
* is outside the range supported by the underlying device.
|
|
*/
|
|
bp->b_ioflags &= ~BIO_ERROR;
|
|
bdirty(bp);
|
|
} else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
|
|
(bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
|
|
/*
|
|
* Either a failed I/O or we were asked to free or not
|
|
* cache the buffer.
|
|
*/
|
|
bp->b_flags |= B_INVAL;
|
|
if (LIST_FIRST(&bp->b_dep) != NULL)
|
|
buf_deallocate(bp);
|
|
if (bp->b_flags & B_DELWRI) {
|
|
atomic_subtract_int(&numdirtybuffers, 1);
|
|
numdirtywakeup(lodirtybuffers);
|
|
}
|
|
bp->b_flags &= ~(B_DELWRI | B_CACHE);
|
|
if ((bp->b_flags & B_VMIO) == 0) {
|
|
if (bp->b_bufsize)
|
|
allocbuf(bp, 0);
|
|
if (bp->b_vp)
|
|
brelvp(bp);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
|
|
* is called with B_DELWRI set, the underlying pages may wind up
|
|
* getting freed causing a previous write (bdwrite()) to get 'lost'
|
|
* because pages associated with a B_DELWRI bp are marked clean.
|
|
*
|
|
* We still allow the B_INVAL case to call vfs_vmio_release(), even
|
|
* if B_DELWRI is set.
|
|
*
|
|
* If B_DELWRI is not set we may have to set B_RELBUF if we are low
|
|
* on pages to return pages to the VM page queues.
|
|
*/
|
|
if (bp->b_flags & B_DELWRI)
|
|
bp->b_flags &= ~B_RELBUF;
|
|
else if (vm_page_count_severe()) {
|
|
/*
|
|
* XXX This lock may not be necessary since BKGRDINPROG
|
|
* cannot be set while we hold the buf lock, it can only be
|
|
* cleared if it is already pending.
|
|
*/
|
|
if (bp->b_vp) {
|
|
BO_LOCK(bp->b_bufobj);
|
|
if (!(bp->b_vflags & BV_BKGRDINPROG))
|
|
bp->b_flags |= B_RELBUF;
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
} else
|
|
bp->b_flags |= B_RELBUF;
|
|
}
|
|
|
|
/*
|
|
* VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
|
|
* constituted, not even NFS buffers now. Two flags effect this. If
|
|
* B_INVAL, the struct buf is invalidated but the VM object is kept
|
|
* around ( i.e. so it is trivial to reconstitute the buffer later ).
|
|
*
|
|
* If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
|
|
* invalidated. BIO_ERROR cannot be set for a failed write unless the
|
|
* buffer is also B_INVAL because it hits the re-dirtying code above.
|
|
*
|
|
* Normally we can do this whether a buffer is B_DELWRI or not. If
|
|
* the buffer is an NFS buffer, it is tracking piecemeal writes or
|
|
* the commit state and we cannot afford to lose the buffer. If the
|
|
* buffer has a background write in progress, we need to keep it
|
|
* around to prevent it from being reconstituted and starting a second
|
|
* background write.
|
|
*/
|
|
if ((bp->b_flags & B_VMIO)
|
|
&& !(bp->b_vp->v_mount != NULL &&
|
|
(bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
|
|
!vn_isdisk(bp->b_vp, NULL) &&
|
|
(bp->b_flags & B_DELWRI))
|
|
) {
|
|
|
|
int i, j, resid;
|
|
vm_page_t m;
|
|
off_t foff;
|
|
vm_pindex_t poff;
|
|
vm_object_t obj;
|
|
|
|
obj = bp->b_bufobj->bo_object;
|
|
|
|
/*
|
|
* Get the base offset and length of the buffer. Note that
|
|
* in the VMIO case if the buffer block size is not
|
|
* page-aligned then b_data pointer may not be page-aligned.
|
|
* But our b_pages[] array *IS* page aligned.
|
|
*
|
|
* block sizes less then DEV_BSIZE (usually 512) are not
|
|
* supported due to the page granularity bits (m->valid,
|
|
* m->dirty, etc...).
|
|
*
|
|
* See man buf(9) for more information
|
|
*/
|
|
resid = bp->b_bufsize;
|
|
foff = bp->b_offset;
|
|
VM_OBJECT_LOCK(obj);
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
int had_bogus = 0;
|
|
|
|
m = bp->b_pages[i];
|
|
|
|
/*
|
|
* If we hit a bogus page, fixup *all* the bogus pages
|
|
* now.
|
|
*/
|
|
if (m == bogus_page) {
|
|
poff = OFF_TO_IDX(bp->b_offset);
|
|
had_bogus = 1;
|
|
|
|
for (j = i; j < bp->b_npages; j++) {
|
|
vm_page_t mtmp;
|
|
mtmp = bp->b_pages[j];
|
|
if (mtmp == bogus_page) {
|
|
mtmp = vm_page_lookup(obj, poff + j);
|
|
if (!mtmp) {
|
|
panic("brelse: page missing\n");
|
|
}
|
|
bp->b_pages[j] = mtmp;
|
|
}
|
|
}
|
|
|
|
if ((bp->b_flags & B_INVAL) == 0) {
|
|
pmap_qenter(
|
|
trunc_page((vm_offset_t)bp->b_data),
|
|
bp->b_pages, bp->b_npages);
|
|
}
|
|
m = bp->b_pages[i];
|
|
}
|
|
if ((bp->b_flags & B_NOCACHE) ||
|
|
(bp->b_ioflags & BIO_ERROR)) {
|
|
int poffset = foff & PAGE_MASK;
|
|
int presid = resid > (PAGE_SIZE - poffset) ?
|
|
(PAGE_SIZE - poffset) : resid;
|
|
|
|
KASSERT(presid >= 0, ("brelse: extra page"));
|
|
vm_page_lock_queues();
|
|
vm_page_set_invalid(m, poffset, presid);
|
|
vm_page_unlock_queues();
|
|
if (had_bogus)
|
|
printf("avoided corruption bug in bogus_page/brelse code\n");
|
|
}
|
|
resid -= PAGE_SIZE - (foff & PAGE_MASK);
|
|
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
|
|
}
|
|
VM_OBJECT_UNLOCK(obj);
|
|
if (bp->b_flags & (B_INVAL | B_RELBUF))
|
|
vfs_vmio_release(bp);
|
|
|
|
} else if (bp->b_flags & B_VMIO) {
|
|
|
|
if (bp->b_flags & (B_INVAL | B_RELBUF)) {
|
|
vfs_vmio_release(bp);
|
|
}
|
|
|
|
}
|
|
|
|
if (BUF_REFCNT(bp) > 1) {
|
|
/* do not release to free list */
|
|
BUF_UNLOCK(bp);
|
|
splx(s);
|
|
return;
|
|
}
|
|
|
|
/* enqueue */
|
|
mtx_lock(&bqlock);
|
|
/* Handle delayed bremfree() processing. */
|
|
if (bp->b_flags & B_REMFREE)
|
|
bremfreel(bp);
|
|
if (bp->b_qindex != QUEUE_NONE)
|
|
panic("brelse: free buffer onto another queue???");
|
|
|
|
/* buffers with no memory */
|
|
if (bp->b_bufsize == 0) {
|
|
bp->b_flags |= B_INVAL;
|
|
bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
|
|
if (bp->b_vflags & BV_BKGRDINPROG)
|
|
panic("losing buffer 1");
|
|
if (bp->b_kvasize) {
|
|
bp->b_qindex = QUEUE_EMPTYKVA;
|
|
} else {
|
|
bp->b_qindex = QUEUE_EMPTY;
|
|
}
|
|
TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
|
|
/* buffers with junk contents */
|
|
} else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
|
|
(bp->b_ioflags & BIO_ERROR)) {
|
|
bp->b_flags |= B_INVAL;
|
|
bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
|
|
if (bp->b_vflags & BV_BKGRDINPROG)
|
|
panic("losing buffer 2");
|
|
bp->b_qindex = QUEUE_CLEAN;
|
|
TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
|
|
/* remaining buffers */
|
|
} else {
|
|
if (bp->b_flags & B_DELWRI)
|
|
bp->b_qindex = QUEUE_DIRTY;
|
|
else
|
|
bp->b_qindex = QUEUE_CLEAN;
|
|
if (bp->b_flags & B_AGE)
|
|
TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
|
|
else
|
|
TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
|
|
}
|
|
mtx_unlock(&bqlock);
|
|
|
|
/*
|
|
* If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already
|
|
* placed the buffer on the correct queue. We must also disassociate
|
|
* the device and vnode for a B_INVAL buffer so gbincore() doesn't
|
|
* find it.
|
|
*/
|
|
if (bp->b_flags & B_INVAL) {
|
|
if (bp->b_flags & B_DELWRI)
|
|
bundirty(bp);
|
|
if (bp->b_vp)
|
|
brelvp(bp);
|
|
}
|
|
|
|
/*
|
|
* Fixup numfreebuffers count. The bp is on an appropriate queue
|
|
* unless locked. We then bump numfreebuffers if it is not B_DELWRI.
|
|
* We've already handled the B_INVAL case ( B_DELWRI will be clear
|
|
* if B_INVAL is set ).
|
|
*/
|
|
|
|
if (!(bp->b_flags & B_DELWRI))
|
|
bufcountwakeup();
|
|
|
|
/*
|
|
* Something we can maybe free or reuse
|
|
*/
|
|
if (bp->b_bufsize || bp->b_kvasize)
|
|
bufspacewakeup();
|
|
|
|
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
|
|
if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
|
|
panic("brelse: not dirty");
|
|
/* unlock */
|
|
BUF_UNLOCK(bp);
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* Release a buffer back to the appropriate queue but do not try to free
|
|
* it. The buffer is expected to be used again soon.
|
|
*
|
|
* bqrelse() is used by bdwrite() to requeue a delayed write, and used by
|
|
* biodone() to requeue an async I/O on completion. It is also used when
|
|
* known good buffers need to be requeued but we think we may need the data
|
|
* again soon.
|
|
*
|
|
* XXX we should be able to leave the B_RELBUF hint set on completion.
|
|
*/
|
|
void
|
|
bqrelse(struct buf *bp)
|
|
{
|
|
int s;
|
|
|
|
s = splbio();
|
|
|
|
KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
|
|
("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
|
|
|
|
if (BUF_REFCNT(bp) > 1) {
|
|
/* do not release to free list */
|
|
BUF_UNLOCK(bp);
|
|
splx(s);
|
|
return;
|
|
}
|
|
mtx_lock(&bqlock);
|
|
/* Handle delayed bremfree() processing. */
|
|
if (bp->b_flags & B_REMFREE)
|
|
bremfreel(bp);
|
|
if (bp->b_qindex != QUEUE_NONE)
|
|
panic("bqrelse: free buffer onto another queue???");
|
|
/* buffers with stale but valid contents */
|
|
if (bp->b_flags & B_DELWRI) {
|
|
bp->b_qindex = QUEUE_DIRTY;
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist);
|
|
} else {
|
|
/*
|
|
* XXX This lock may not be necessary since BKGRDINPROG
|
|
* cannot be set while we hold the buf lock, it can only be
|
|
* cleared if it is already pending.
|
|
*/
|
|
BO_LOCK(bp->b_bufobj);
|
|
if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) {
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
bp->b_qindex = QUEUE_CLEAN;
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
|
|
b_freelist);
|
|
} else {
|
|
/*
|
|
* We are too low on memory, we have to try to free
|
|
* the buffer (most importantly: the wired pages
|
|
* making up its backing store) *now*.
|
|
*/
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
mtx_unlock(&bqlock);
|
|
splx(s);
|
|
brelse(bp);
|
|
return;
|
|
}
|
|
}
|
|
mtx_unlock(&bqlock);
|
|
|
|
if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
|
|
bufcountwakeup();
|
|
|
|
/*
|
|
* Something we can maybe free or reuse.
|
|
*/
|
|
if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
|
|
bufspacewakeup();
|
|
|
|
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
|
|
if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
|
|
panic("bqrelse: not dirty");
|
|
/* unlock */
|
|
BUF_UNLOCK(bp);
|
|
splx(s);
|
|
}
|
|
|
|
/* Give pages used by the bp back to the VM system (where possible) */
|
|
static void
|
|
vfs_vmio_release(struct buf *bp)
|
|
{
|
|
int i;
|
|
vm_page_t m;
|
|
|
|
GIANT_REQUIRED;
|
|
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
|
|
vm_page_lock_queues();
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
m = bp->b_pages[i];
|
|
bp->b_pages[i] = NULL;
|
|
/*
|
|
* In order to keep page LRU ordering consistent, put
|
|
* everything on the inactive queue.
|
|
*/
|
|
vm_page_unwire(m, 0);
|
|
/*
|
|
* We don't mess with busy pages, it is
|
|
* the responsibility of the process that
|
|
* busied the pages to deal with them.
|
|
*/
|
|
if ((m->flags & PG_BUSY) || (m->busy != 0))
|
|
continue;
|
|
|
|
if (m->wire_count == 0) {
|
|
/*
|
|
* Might as well free the page if we can and it has
|
|
* no valid data. We also free the page if the
|
|
* buffer was used for direct I/O
|
|
*/
|
|
if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
|
|
m->hold_count == 0) {
|
|
pmap_remove_all(m);
|
|
vm_page_free(m);
|
|
} else if (bp->b_flags & B_DIRECT) {
|
|
vm_page_try_to_free(m);
|
|
} else if (vm_page_count_severe()) {
|
|
vm_page_try_to_cache(m);
|
|
}
|
|
}
|
|
}
|
|
vm_page_unlock_queues();
|
|
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
|
|
pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
|
|
|
|
if (bp->b_bufsize) {
|
|
bufspacewakeup();
|
|
bp->b_bufsize = 0;
|
|
}
|
|
bp->b_npages = 0;
|
|
bp->b_flags &= ~B_VMIO;
|
|
if (bp->b_vp)
|
|
brelvp(bp);
|
|
}
|
|
|
|
/*
|
|
* Check to see if a block at a particular lbn is available for a clustered
|
|
* write.
|
|
*/
|
|
static int
|
|
vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
|
|
{
|
|
struct buf *bpa;
|
|
int match;
|
|
|
|
match = 0;
|
|
|
|
/* If the buf isn't in core skip it */
|
|
if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
|
|
return (0);
|
|
|
|
/* If the buf is busy we don't want to wait for it */
|
|
if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
|
|
return (0);
|
|
|
|
/* Only cluster with valid clusterable delayed write buffers */
|
|
if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
|
|
(B_DELWRI | B_CLUSTEROK))
|
|
goto done;
|
|
|
|
if (bpa->b_bufsize != size)
|
|
goto done;
|
|
|
|
/*
|
|
* Check to see if it is in the expected place on disk and that the
|
|
* block has been mapped.
|
|
*/
|
|
if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
|
|
match = 1;
|
|
done:
|
|
BUF_UNLOCK(bpa);
|
|
return (match);
|
|
}
|
|
|
|
/*
|
|
* vfs_bio_awrite:
|
|
*
|
|
* Implement clustered async writes for clearing out B_DELWRI buffers.
|
|
* This is much better then the old way of writing only one buffer at
|
|
* a time. Note that we may not be presented with the buffers in the
|
|
* correct order, so we search for the cluster in both directions.
|
|
*/
|
|
int
|
|
vfs_bio_awrite(struct buf *bp)
|
|
{
|
|
int i;
|
|
int j;
|
|
daddr_t lblkno = bp->b_lblkno;
|
|
struct vnode *vp = bp->b_vp;
|
|
int s;
|
|
int ncl;
|
|
int nwritten;
|
|
int size;
|
|
int maxcl;
|
|
|
|
s = splbio();
|
|
/*
|
|
* right now we support clustered writing only to regular files. If
|
|
* we find a clusterable block we could be in the middle of a cluster
|
|
* rather then at the beginning.
|
|
*/
|
|
if ((vp->v_type == VREG) &&
|
|
(vp->v_mount != 0) && /* Only on nodes that have the size info */
|
|
(bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
|
|
|
|
size = vp->v_mount->mnt_stat.f_iosize;
|
|
maxcl = MAXPHYS / size;
|
|
|
|
VI_LOCK(vp);
|
|
for (i = 1; i < maxcl; i++)
|
|
if (vfs_bio_clcheck(vp, size, lblkno + i,
|
|
bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
|
|
break;
|
|
|
|
for (j = 1; i + j <= maxcl && j <= lblkno; j++)
|
|
if (vfs_bio_clcheck(vp, size, lblkno - j,
|
|
bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
|
|
break;
|
|
|
|
VI_UNLOCK(vp);
|
|
--j;
|
|
ncl = i + j;
|
|
/*
|
|
* this is a possible cluster write
|
|
*/
|
|
if (ncl != 1) {
|
|
BUF_UNLOCK(bp);
|
|
nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
|
|
splx(s);
|
|
return nwritten;
|
|
}
|
|
}
|
|
|
|
bremfree(bp);
|
|
bp->b_flags |= B_ASYNC;
|
|
|
|
splx(s);
|
|
/*
|
|
* default (old) behavior, writing out only one block
|
|
*
|
|
* XXX returns b_bufsize instead of b_bcount for nwritten?
|
|
*/
|
|
nwritten = bp->b_bufsize;
|
|
(void) bwrite(bp);
|
|
|
|
return nwritten;
|
|
}
|
|
|
|
/*
|
|
* getnewbuf:
|
|
*
|
|
* Find and initialize a new buffer header, freeing up existing buffers
|
|
* in the bufqueues as necessary. The new buffer is returned locked.
|
|
*
|
|
* Important: B_INVAL is not set. If the caller wishes to throw the
|
|
* buffer away, the caller must set B_INVAL prior to calling brelse().
|
|
*
|
|
* We block if:
|
|
* We have insufficient buffer headers
|
|
* We have insufficient buffer space
|
|
* buffer_map is too fragmented ( space reservation fails )
|
|
* If we have to flush dirty buffers ( but we try to avoid this )
|
|
*
|
|
* To avoid VFS layer recursion we do not flush dirty buffers ourselves.
|
|
* Instead we ask the buf daemon to do it for us. We attempt to
|
|
* avoid piecemeal wakeups of the pageout daemon.
|
|
*/
|
|
|
|
static struct buf *
|
|
getnewbuf(int slpflag, int slptimeo, int size, int maxsize)
|
|
{
|
|
struct buf *bp;
|
|
struct buf *nbp;
|
|
int defrag = 0;
|
|
int nqindex;
|
|
static int flushingbufs;
|
|
|
|
GIANT_REQUIRED;
|
|
|
|
/*
|
|
* We can't afford to block since we might be holding a vnode lock,
|
|
* which may prevent system daemons from running. We deal with
|
|
* low-memory situations by proactively returning memory and running
|
|
* async I/O rather then sync I/O.
|
|
*/
|
|
|
|
atomic_add_int(&getnewbufcalls, 1);
|
|
atomic_subtract_int(&getnewbufrestarts, 1);
|
|
restart:
|
|
atomic_add_int(&getnewbufrestarts, 1);
|
|
|
|
/*
|
|
* Setup for scan. If we do not have enough free buffers,
|
|
* we setup a degenerate case that immediately fails. Note
|
|
* that if we are specially marked process, we are allowed to
|
|
* dip into our reserves.
|
|
*
|
|
* The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
|
|
*
|
|
* We start with EMPTYKVA. If the list is empty we backup to EMPTY.
|
|
* However, there are a number of cases (defragging, reusing, ...)
|
|
* where we cannot backup.
|
|
*/
|
|
mtx_lock(&bqlock);
|
|
nqindex = QUEUE_EMPTYKVA;
|
|
nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
|
|
|
|
if (nbp == NULL) {
|
|
/*
|
|
* If no EMPTYKVA buffers and we are either
|
|
* defragging or reusing, locate a CLEAN buffer
|
|
* to free or reuse. If bufspace useage is low
|
|
* skip this step so we can allocate a new buffer.
|
|
*/
|
|
if (defrag || bufspace >= lobufspace) {
|
|
nqindex = QUEUE_CLEAN;
|
|
nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
|
|
}
|
|
|
|
/*
|
|
* If we could not find or were not allowed to reuse a
|
|
* CLEAN buffer, check to see if it is ok to use an EMPTY
|
|
* buffer. We can only use an EMPTY buffer if allocating
|
|
* its KVA would not otherwise run us out of buffer space.
|
|
*/
|
|
if (nbp == NULL && defrag == 0 &&
|
|
bufspace + maxsize < hibufspace) {
|
|
nqindex = QUEUE_EMPTY;
|
|
nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Run scan, possibly freeing data and/or kva mappings on the fly
|
|
* depending.
|
|
*/
|
|
|
|
while ((bp = nbp) != NULL) {
|
|
int qindex = nqindex;
|
|
|
|
/*
|
|
* Calculate next bp ( we can only use it if we do not block
|
|
* or do other fancy things ).
|
|
*/
|
|
if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
|
|
switch(qindex) {
|
|
case QUEUE_EMPTY:
|
|
nqindex = QUEUE_EMPTYKVA;
|
|
if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
|
|
break;
|
|
/* FALLTHROUGH */
|
|
case QUEUE_EMPTYKVA:
|
|
nqindex = QUEUE_CLEAN;
|
|
if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
|
|
break;
|
|
/* FALLTHROUGH */
|
|
case QUEUE_CLEAN:
|
|
/*
|
|
* nbp is NULL.
|
|
*/
|
|
break;
|
|
}
|
|
}
|
|
if (bp->b_vp) {
|
|
BO_LOCK(bp->b_bufobj);
|
|
if (bp->b_vflags & BV_BKGRDINPROG) {
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
continue;
|
|
}
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
}
|
|
|
|
/*
|
|
* If we are defragging then we need a buffer with
|
|
* b_kvasize != 0. XXX this situation should no longer
|
|
* occur, if defrag is non-zero the buffer's b_kvasize
|
|
* should also be non-zero at this point. XXX
|
|
*/
|
|
if (defrag && bp->b_kvasize == 0) {
|
|
printf("Warning: defrag empty buffer %p\n", bp);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Start freeing the bp. This is somewhat involved. nbp
|
|
* remains valid only for QUEUE_EMPTY[KVA] bp's.
|
|
*/
|
|
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
|
|
continue;
|
|
/*
|
|
* Sanity Checks
|
|
*/
|
|
KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
|
|
|
|
/*
|
|
* Note: we no longer distinguish between VMIO and non-VMIO
|
|
* buffers.
|
|
*/
|
|
|
|
KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
|
|
|
|
bremfreel(bp);
|
|
mtx_unlock(&bqlock);
|
|
|
|
if (qindex == QUEUE_CLEAN) {
|
|
if (bp->b_flags & B_VMIO) {
|
|
bp->b_flags &= ~B_ASYNC;
|
|
vfs_vmio_release(bp);
|
|
}
|
|
if (bp->b_vp)
|
|
brelvp(bp);
|
|
}
|
|
|
|
/*
|
|
* NOTE: nbp is now entirely invalid. We can only restart
|
|
* the scan from this point on.
|
|
*
|
|
* Get the rest of the buffer freed up. b_kva* is still
|
|
* valid after this operation.
|
|
*/
|
|
|
|
if (bp->b_rcred != NOCRED) {
|
|
crfree(bp->b_rcred);
|
|
bp->b_rcred = NOCRED;
|
|
}
|
|
if (bp->b_wcred != NOCRED) {
|
|
crfree(bp->b_wcred);
|
|
bp->b_wcred = NOCRED;
|
|
}
|
|
if (LIST_FIRST(&bp->b_dep) != NULL)
|
|
buf_deallocate(bp);
|
|
if (bp->b_vflags & BV_BKGRDINPROG)
|
|
panic("losing buffer 3");
|
|
|
|
if (bp->b_bufsize)
|
|
allocbuf(bp, 0);
|
|
|
|
bp->b_flags = 0;
|
|
bp->b_ioflags = 0;
|
|
bp->b_xflags = 0;
|
|
bp->b_vflags = 0;
|
|
bp->b_vp = NULL;
|
|
bp->b_blkno = bp->b_lblkno = 0;
|
|
bp->b_offset = NOOFFSET;
|
|
bp->b_iodone = 0;
|
|
bp->b_error = 0;
|
|
bp->b_resid = 0;
|
|
bp->b_bcount = 0;
|
|
bp->b_npages = 0;
|
|
bp->b_dirtyoff = bp->b_dirtyend = 0;
|
|
bp->b_bufobj = NULL;
|
|
|
|
LIST_INIT(&bp->b_dep);
|
|
|
|
/*
|
|
* If we are defragging then free the buffer.
|
|
*/
|
|
if (defrag) {
|
|
bp->b_flags |= B_INVAL;
|
|
bfreekva(bp);
|
|
brelse(bp);
|
|
defrag = 0;
|
|
goto restart;
|
|
}
|
|
|
|
/*
|
|
* If we are overcomitted then recover the buffer and its
|
|
* KVM space. This occurs in rare situations when multiple
|
|
* processes are blocked in getnewbuf() or allocbuf().
|
|
*/
|
|
if (bufspace >= hibufspace)
|
|
flushingbufs = 1;
|
|
if (flushingbufs && bp->b_kvasize != 0) {
|
|
bp->b_flags |= B_INVAL;
|
|
bfreekva(bp);
|
|
brelse(bp);
|
|
goto restart;
|
|
}
|
|
if (bufspace < lobufspace)
|
|
flushingbufs = 0;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If we exhausted our list, sleep as appropriate. We may have to
|
|
* wakeup various daemons and write out some dirty buffers.
|
|
*
|
|
* Generally we are sleeping due to insufficient buffer space.
|
|
*/
|
|
|
|
if (bp == NULL) {
|
|
int flags;
|
|
char *waitmsg;
|
|
|
|
mtx_unlock(&bqlock);
|
|
if (defrag) {
|
|
flags = VFS_BIO_NEED_BUFSPACE;
|
|
waitmsg = "nbufkv";
|
|
} else if (bufspace >= hibufspace) {
|
|
waitmsg = "nbufbs";
|
|
flags = VFS_BIO_NEED_BUFSPACE;
|
|
} else {
|
|
waitmsg = "newbuf";
|
|
flags = VFS_BIO_NEED_ANY;
|
|
}
|
|
|
|
bd_speedup(); /* heeeelp */
|
|
|
|
mtx_lock(&nblock);
|
|
needsbuffer |= flags;
|
|
while (needsbuffer & flags) {
|
|
if (msleep(&needsbuffer, &nblock,
|
|
(PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
|
|
mtx_unlock(&nblock);
|
|
return (NULL);
|
|
}
|
|
}
|
|
mtx_unlock(&nblock);
|
|
} else {
|
|
/*
|
|
* We finally have a valid bp. We aren't quite out of the
|
|
* woods, we still have to reserve kva space. In order
|
|
* to keep fragmentation sane we only allocate kva in
|
|
* BKVASIZE chunks.
|
|
*/
|
|
maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
|
|
|
|
if (maxsize != bp->b_kvasize) {
|
|
vm_offset_t addr = 0;
|
|
|
|
bfreekva(bp);
|
|
|
|
if (vm_map_findspace(buffer_map,
|
|
vm_map_min(buffer_map), maxsize, &addr)) {
|
|
/*
|
|
* Uh oh. Buffer map is to fragmented. We
|
|
* must defragment the map.
|
|
*/
|
|
atomic_add_int(&bufdefragcnt, 1);
|
|
defrag = 1;
|
|
bp->b_flags |= B_INVAL;
|
|
brelse(bp);
|
|
goto restart;
|
|
}
|
|
if (addr) {
|
|
vm_map_insert(buffer_map, NULL, 0,
|
|
addr, addr + maxsize,
|
|
VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
|
|
|
|
bp->b_kvabase = (caddr_t) addr;
|
|
bp->b_kvasize = maxsize;
|
|
atomic_add_int(&bufspace, bp->b_kvasize);
|
|
atomic_add_int(&bufreusecnt, 1);
|
|
}
|
|
}
|
|
bp->b_saveaddr = bp->b_kvabase;
|
|
bp->b_data = bp->b_saveaddr;
|
|
}
|
|
return(bp);
|
|
}
|
|
|
|
/*
|
|
* buf_daemon:
|
|
*
|
|
* buffer flushing daemon. Buffers are normally flushed by the
|
|
* update daemon but if it cannot keep up this process starts to
|
|
* take the load in an attempt to prevent getnewbuf() from blocking.
|
|
*/
|
|
|
|
static struct kproc_desc buf_kp = {
|
|
"bufdaemon",
|
|
buf_daemon,
|
|
&bufdaemonproc
|
|
};
|
|
SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp)
|
|
|
|
static void
|
|
buf_daemon()
|
|
{
|
|
int s;
|
|
|
|
mtx_lock(&Giant);
|
|
|
|
/*
|
|
* This process needs to be suspended prior to shutdown sync.
|
|
*/
|
|
EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
|
|
SHUTDOWN_PRI_LAST);
|
|
|
|
/*
|
|
* This process is allowed to take the buffer cache to the limit
|
|
*/
|
|
s = splbio();
|
|
mtx_lock(&bdlock);
|
|
|
|
for (;;) {
|
|
bd_request = 0;
|
|
mtx_unlock(&bdlock);
|
|
|
|
kthread_suspend_check(bufdaemonproc);
|
|
|
|
/*
|
|
* Do the flush. Limit the amount of in-transit I/O we
|
|
* allow to build up, otherwise we would completely saturate
|
|
* the I/O system. Wakeup any waiting processes before we
|
|
* normally would so they can run in parallel with our drain.
|
|
*/
|
|
while (numdirtybuffers > lodirtybuffers) {
|
|
if (flushbufqueues(0) == 0) {
|
|
/*
|
|
* Could not find any buffers without rollback
|
|
* dependencies, so just write the first one
|
|
* in the hopes of eventually making progress.
|
|
*/
|
|
flushbufqueues(1);
|
|
break;
|
|
}
|
|
waitrunningbufspace();
|
|
numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
|
|
}
|
|
|
|
/*
|
|
* Only clear bd_request if we have reached our low water
|
|
* mark. The buf_daemon normally waits 1 second and
|
|
* then incrementally flushes any dirty buffers that have
|
|
* built up, within reason.
|
|
*
|
|
* If we were unable to hit our low water mark and couldn't
|
|
* find any flushable buffers, we sleep half a second.
|
|
* Otherwise we loop immediately.
|
|
*/
|
|
mtx_lock(&bdlock);
|
|
if (numdirtybuffers <= lodirtybuffers) {
|
|
/*
|
|
* We reached our low water mark, reset the
|
|
* request and sleep until we are needed again.
|
|
* The sleep is just so the suspend code works.
|
|
*/
|
|
bd_request = 0;
|
|
msleep(&bd_request, &bdlock, PVM, "psleep", hz);
|
|
} else {
|
|
/*
|
|
* We couldn't find any flushable dirty buffers but
|
|
* still have too many dirty buffers, we
|
|
* have to sleep and try again. (rare)
|
|
*/
|
|
msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* flushbufqueues:
|
|
*
|
|
* Try to flush a buffer in the dirty queue. We must be careful to
|
|
* free up B_INVAL buffers instead of write them, which NFS is
|
|
* particularly sensitive to.
|
|
*/
|
|
int flushwithdeps = 0;
|
|
SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
|
|
0, "Number of buffers flushed with dependecies that require rollbacks");
|
|
|
|
static int
|
|
flushbufqueues(int flushdeps)
|
|
{
|
|
struct thread *td = curthread;
|
|
struct vnode *vp;
|
|
struct mount *mp;
|
|
struct buf *bp;
|
|
int hasdeps;
|
|
|
|
mtx_lock(&bqlock);
|
|
TAILQ_FOREACH(bp, &bufqueues[QUEUE_DIRTY], b_freelist) {
|
|
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
|
|
continue;
|
|
KASSERT((bp->b_flags & B_DELWRI),
|
|
("unexpected clean buffer %p", bp));
|
|
BO_LOCK(bp->b_bufobj);
|
|
if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
BUF_UNLOCK(bp);
|
|
continue;
|
|
}
|
|
BO_UNLOCK(bp->b_bufobj);
|
|
if (bp->b_flags & B_INVAL) {
|
|
bremfreel(bp);
|
|
mtx_unlock(&bqlock);
|
|
brelse(bp);
|
|
return (1);
|
|
}
|
|
|
|
if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) {
|
|
if (flushdeps == 0) {
|
|
BUF_UNLOCK(bp);
|
|
continue;
|
|
}
|
|
hasdeps = 1;
|
|
} else
|
|
hasdeps = 0;
|
|
/*
|
|
* We must hold the lock on a vnode before writing
|
|
* one of its buffers. Otherwise we may confuse, or
|
|
* in the case of a snapshot vnode, deadlock the
|
|
* system.
|
|
*
|
|
* The lock order here is the reverse of the normal
|
|
* of vnode followed by buf lock. This is ok because
|
|
* the NOWAIT will prevent deadlock.
|
|
*/
|
|
vp = bp->b_vp;
|
|
if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
|
|
BUF_UNLOCK(bp);
|
|
continue;
|
|
}
|
|
if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) {
|
|
mtx_unlock(&bqlock);
|
|
vfs_bio_awrite(bp);
|
|
vn_finished_write(mp);
|
|
VOP_UNLOCK(vp, 0, td);
|
|
flushwithdeps += hasdeps;
|
|
return (1);
|
|
}
|
|
vn_finished_write(mp);
|
|
BUF_UNLOCK(bp);
|
|
}
|
|
mtx_unlock(&bqlock);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Check to see if a block is currently memory resident.
|
|
*/
|
|
struct buf *
|
|
incore(struct bufobj *bo, daddr_t blkno)
|
|
{
|
|
struct buf *bp;
|
|
|
|
int s = splbio();
|
|
BO_LOCK(bo);
|
|
bp = gbincore(bo, blkno);
|
|
BO_UNLOCK(bo);
|
|
splx(s);
|
|
return (bp);
|
|
}
|
|
|
|
/*
|
|
* Returns true if no I/O is needed to access the
|
|
* associated VM object. This is like incore except
|
|
* it also hunts around in the VM system for the data.
|
|
*/
|
|
|
|
static int
|
|
inmem(struct vnode * vp, daddr_t blkno)
|
|
{
|
|
vm_object_t obj;
|
|
vm_offset_t toff, tinc, size;
|
|
vm_page_t m;
|
|
vm_ooffset_t off;
|
|
|
|
GIANT_REQUIRED;
|
|
ASSERT_VOP_LOCKED(vp, "inmem");
|
|
|
|
if (incore(&vp->v_bufobj, blkno))
|
|
return 1;
|
|
if (vp->v_mount == NULL)
|
|
return 0;
|
|
if (VOP_GETVOBJECT(vp, &obj) != 0 || (vp->v_vflag & VV_OBJBUF) == 0)
|
|
return 0;
|
|
|
|
size = PAGE_SIZE;
|
|
if (size > vp->v_mount->mnt_stat.f_iosize)
|
|
size = vp->v_mount->mnt_stat.f_iosize;
|
|
off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
|
|
|
|
VM_OBJECT_LOCK(obj);
|
|
for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
|
|
m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
|
|
if (!m)
|
|
goto notinmem;
|
|
tinc = size;
|
|
if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
|
|
tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
|
|
if (vm_page_is_valid(m,
|
|
(vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
|
|
goto notinmem;
|
|
}
|
|
VM_OBJECT_UNLOCK(obj);
|
|
return 1;
|
|
|
|
notinmem:
|
|
VM_OBJECT_UNLOCK(obj);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* vfs_setdirty:
|
|
*
|
|
* Sets the dirty range for a buffer based on the status of the dirty
|
|
* bits in the pages comprising the buffer.
|
|
*
|
|
* The range is limited to the size of the buffer.
|
|
*
|
|
* This routine is primarily used by NFS, but is generalized for the
|
|
* B_VMIO case.
|
|
*/
|
|
static void
|
|
vfs_setdirty(struct buf *bp)
|
|
{
|
|
int i;
|
|
vm_object_t object;
|
|
|
|
GIANT_REQUIRED;
|
|
/*
|
|
* Degenerate case - empty buffer
|
|
*/
|
|
|
|
if (bp->b_bufsize == 0)
|
|
return;
|
|
|
|
/*
|
|
* We qualify the scan for modified pages on whether the
|
|
* object has been flushed yet. The OBJ_WRITEABLE flag
|
|
* is not cleared simply by protecting pages off.
|
|
*/
|
|
|
|
if ((bp->b_flags & B_VMIO) == 0)
|
|
return;
|
|
|
|
object = bp->b_pages[0]->object;
|
|
VM_OBJECT_LOCK(object);
|
|
if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY))
|
|
printf("Warning: object %p writeable but not mightbedirty\n", object);
|
|
if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY))
|
|
printf("Warning: object %p mightbedirty but not writeable\n", object);
|
|
|
|
if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
|
|
vm_offset_t boffset;
|
|
vm_offset_t eoffset;
|
|
|
|
vm_page_lock_queues();
|
|
/*
|
|
* test the pages to see if they have been modified directly
|
|
* by users through the VM system.
|
|
*/
|
|
for (i = 0; i < bp->b_npages; i++)
|
|
vm_page_test_dirty(bp->b_pages[i]);
|
|
|
|
/*
|
|
* Calculate the encompassing dirty range, boffset and eoffset,
|
|
* (eoffset - boffset) bytes.
|
|
*/
|
|
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
if (bp->b_pages[i]->dirty)
|
|
break;
|
|
}
|
|
boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
|
|
|
|
for (i = bp->b_npages - 1; i >= 0; --i) {
|
|
if (bp->b_pages[i]->dirty) {
|
|
break;
|
|
}
|
|
}
|
|
eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
|
|
|
|
vm_page_unlock_queues();
|
|
/*
|
|
* Fit it to the buffer.
|
|
*/
|
|
|
|
if (eoffset > bp->b_bcount)
|
|
eoffset = bp->b_bcount;
|
|
|
|
/*
|
|
* If we have a good dirty range, merge with the existing
|
|
* dirty range.
|
|
*/
|
|
|
|
if (boffset < eoffset) {
|
|
if (bp->b_dirtyoff > boffset)
|
|
bp->b_dirtyoff = boffset;
|
|
if (bp->b_dirtyend < eoffset)
|
|
bp->b_dirtyend = eoffset;
|
|
}
|
|
}
|
|
VM_OBJECT_UNLOCK(object);
|
|
}
|
|
|
|
/*
|
|
* getblk:
|
|
*
|
|
* Get a block given a specified block and offset into a file/device.
|
|
* The buffers B_DONE bit will be cleared on return, making it almost
|
|
* ready for an I/O initiation. B_INVAL may or may not be set on
|
|
* return. The caller should clear B_INVAL prior to initiating a
|
|
* READ.
|
|
*
|
|
* For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
|
|
* an existing buffer.
|
|
*
|
|
* For a VMIO buffer, B_CACHE is modified according to the backing VM.
|
|
* If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
|
|
* and then cleared based on the backing VM. If the previous buffer is
|
|
* non-0-sized but invalid, B_CACHE will be cleared.
|
|
*
|
|
* If getblk() must create a new buffer, the new buffer is returned with
|
|
* both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
|
|
* case it is returned with B_INVAL clear and B_CACHE set based on the
|
|
* backing VM.
|
|
*
|
|
* getblk() also forces a bwrite() for any B_DELWRI buffer whos
|
|
* B_CACHE bit is clear.
|
|
*
|
|
* What this means, basically, is that the caller should use B_CACHE to
|
|
* determine whether the buffer is fully valid or not and should clear
|
|
* B_INVAL prior to issuing a read. If the caller intends to validate
|
|
* the buffer by loading its data area with something, the caller needs
|
|
* to clear B_INVAL. If the caller does this without issuing an I/O,
|
|
* the caller should set B_CACHE ( as an optimization ), else the caller
|
|
* should issue the I/O and biodone() will set B_CACHE if the I/O was
|
|
* a write attempt or if it was a successfull read. If the caller
|
|
* intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
|
|
* prior to issuing the READ. biodone() will *not* clear B_INVAL.
|
|
*/
|
|
struct buf *
|
|
getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
|
|
int flags)
|
|
{
|
|
struct buf *bp;
|
|
struct bufobj *bo;
|
|
int s;
|
|
int error;
|
|
ASSERT_VOP_LOCKED(vp, "getblk");
|
|
struct vm_object *vmo;
|
|
|
|
if (size > MAXBSIZE)
|
|
panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
|
|
|
|
bo = &vp->v_bufobj;
|
|
s = splbio();
|
|
loop:
|
|
/*
|
|
* Block if we are low on buffers. Certain processes are allowed
|
|
* to completely exhaust the buffer cache.
|
|
*
|
|
* If this check ever becomes a bottleneck it may be better to
|
|
* move it into the else, when gbincore() fails. At the moment
|
|
* it isn't a problem.
|
|
*
|
|
* XXX remove if 0 sections (clean this up after its proven)
|
|
*/
|
|
if (numfreebuffers == 0) {
|
|
if (curthread == PCPU_GET(idlethread))
|
|
return NULL;
|
|
mtx_lock(&nblock);
|
|
needsbuffer |= VFS_BIO_NEED_ANY;
|
|
mtx_unlock(&nblock);
|
|
}
|
|
|
|
VI_LOCK(vp);
|
|
bp = gbincore(bo, blkno);
|
|
if (bp != NULL) {
|
|
int lockflags;
|
|
/*
|
|
* Buffer is in-core. If the buffer is not busy, it must
|
|
* be on a queue.
|
|
*/
|
|
lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
|
|
|
|
if (flags & GB_LOCK_NOWAIT)
|
|
lockflags |= LK_NOWAIT;
|
|
|
|
error = BUF_TIMELOCK(bp, lockflags,
|
|
VI_MTX(vp), "getblk", slpflag, slptimeo);
|
|
|
|
/*
|
|
* If we slept and got the lock we have to restart in case
|
|
* the buffer changed identities.
|
|
*/
|
|
if (error == ENOLCK)
|
|
goto loop;
|
|
/* We timed out or were interrupted. */
|
|
else if (error)
|
|
return (NULL);
|
|
|
|
/*
|
|
* The buffer is locked. B_CACHE is cleared if the buffer is
|
|
* invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
|
|
* and for a VMIO buffer B_CACHE is adjusted according to the
|
|
* backing VM cache.
|
|
*/
|
|
if (bp->b_flags & B_INVAL)
|
|
bp->b_flags &= ~B_CACHE;
|
|
else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
|
|
bp->b_flags |= B_CACHE;
|
|
bremfree(bp);
|
|
|
|
/*
|
|
* check for size inconsistancies for non-VMIO case.
|
|
*/
|
|
|
|
if (bp->b_bcount != size) {
|
|
if ((bp->b_flags & B_VMIO) == 0 ||
|
|
(size > bp->b_kvasize)) {
|
|
if (bp->b_flags & B_DELWRI) {
|
|
bp->b_flags |= B_NOCACHE;
|
|
bwrite(bp);
|
|
} else {
|
|
if ((bp->b_flags & B_VMIO) &&
|
|
(LIST_FIRST(&bp->b_dep) == NULL)) {
|
|
bp->b_flags |= B_RELBUF;
|
|
brelse(bp);
|
|
} else {
|
|
bp->b_flags |= B_NOCACHE;
|
|
bwrite(bp);
|
|
}
|
|
}
|
|
goto loop;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If the size is inconsistant in the VMIO case, we can resize
|
|
* the buffer. This might lead to B_CACHE getting set or
|
|
* cleared. If the size has not changed, B_CACHE remains
|
|
* unchanged from its previous state.
|
|
*/
|
|
|
|
if (bp->b_bcount != size)
|
|
allocbuf(bp, size);
|
|
|
|
KASSERT(bp->b_offset != NOOFFSET,
|
|
("getblk: no buffer offset"));
|
|
|
|
/*
|
|
* A buffer with B_DELWRI set and B_CACHE clear must
|
|
* be committed before we can return the buffer in
|
|
* order to prevent the caller from issuing a read
|
|
* ( due to B_CACHE not being set ) and overwriting
|
|
* it.
|
|
*
|
|
* Most callers, including NFS and FFS, need this to
|
|
* operate properly either because they assume they
|
|
* can issue a read if B_CACHE is not set, or because
|
|
* ( for example ) an uncached B_DELWRI might loop due
|
|
* to softupdates re-dirtying the buffer. In the latter
|
|
* case, B_CACHE is set after the first write completes,
|
|
* preventing further loops.
|
|
* NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
|
|
* above while extending the buffer, we cannot allow the
|
|
* buffer to remain with B_CACHE set after the write
|
|
* completes or it will represent a corrupt state. To
|
|
* deal with this we set B_NOCACHE to scrap the buffer
|
|
* after the write.
|
|
*
|
|
* We might be able to do something fancy, like setting
|
|
* B_CACHE in bwrite() except if B_DELWRI is already set,
|
|
* so the below call doesn't set B_CACHE, but that gets real
|
|
* confusing. This is much easier.
|
|
*/
|
|
|
|
if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
|
|
bp->b_flags |= B_NOCACHE;
|
|
bwrite(bp);
|
|
goto loop;
|
|
}
|
|
|
|
splx(s);
|
|
bp->b_flags &= ~B_DONE;
|
|
} else {
|
|
int bsize, maxsize, vmio;
|
|
off_t offset;
|
|
|
|
/*
|
|
* Buffer is not in-core, create new buffer. The buffer
|
|
* returned by getnewbuf() is locked. Note that the returned
|
|
* buffer is also considered valid (not marked B_INVAL).
|
|
*/
|
|
VI_UNLOCK(vp);
|
|
/*
|
|
* If the user does not want us to create the buffer, bail out
|
|
* here.
|
|
*/
|
|
if (flags & GB_NOCREAT) {
|
|
splx(s);
|
|
return NULL;
|
|
}
|
|
|
|
bsize = bo->bo_bsize;
|
|
offset = blkno * bsize;
|
|
vmio = (VOP_GETVOBJECT(vp, NULL) == 0) &&
|
|
(vp->v_vflag & VV_OBJBUF);
|
|
maxsize = vmio ? size + (offset & PAGE_MASK) : size;
|
|
maxsize = imax(maxsize, bsize);
|
|
|
|
bp = getnewbuf(slpflag, slptimeo, size, maxsize);
|
|
if (bp == NULL) {
|
|
if (slpflag || slptimeo) {
|
|
splx(s);
|
|
return NULL;
|
|
}
|
|
goto loop;
|
|
}
|
|
|
|
/*
|
|
* This code is used to make sure that a buffer is not
|
|
* created while the getnewbuf routine is blocked.
|
|
* This can be a problem whether the vnode is locked or not.
|
|
* If the buffer is created out from under us, we have to
|
|
* throw away the one we just created. There is now window
|
|
* race because we are safely running at splbio() from the
|
|
* point of the duplicate buffer creation through to here,
|
|
* and we've locked the buffer.
|
|
*
|
|
* Note: this must occur before we associate the buffer
|
|
* with the vp especially considering limitations in
|
|
* the splay tree implementation when dealing with duplicate
|
|
* lblkno's.
|
|
*/
|
|
BO_LOCK(bo);
|
|
if (gbincore(bo, blkno)) {
|
|
BO_UNLOCK(bo);
|
|
bp->b_flags |= B_INVAL;
|
|
brelse(bp);
|
|
goto loop;
|
|
}
|
|
|
|
/*
|
|
* Insert the buffer into the hash, so that it can
|
|
* be found by incore.
|
|
*/
|
|
bp->b_blkno = bp->b_lblkno = blkno;
|
|
bp->b_offset = offset;
|
|
|
|
bgetvp(vp, bp);
|
|
BO_UNLOCK(bo);
|
|
|
|
/*
|
|
* set B_VMIO bit. allocbuf() the buffer bigger. Since the
|
|
* buffer size starts out as 0, B_CACHE will be set by
|
|
* allocbuf() for the VMIO case prior to it testing the
|
|
* backing store for validity.
|
|
*/
|
|
|
|
if (vmio) {
|
|
bp->b_flags |= B_VMIO;
|
|
#if defined(VFS_BIO_DEBUG)
|
|
if (vn_canvmio(vp) != TRUE)
|
|
printf("getblk: VMIO on vnode type %d\n",
|
|
vp->v_type);
|
|
#endif
|
|
VOP_GETVOBJECT(vp, &vmo);
|
|
KASSERT(vmo == bp->b_bufobj->bo_object,
|
|
("ARGH! different b_bufobj->bo_object %p %p %p\n",
|
|
bp, vmo, bp->b_bufobj->bo_object));
|
|
} else {
|
|
bp->b_flags &= ~B_VMIO;
|
|
KASSERT(bp->b_bufobj->bo_object == NULL,
|
|
("ARGH! has b_bufobj->bo_object %p %p\n",
|
|
bp, bp->b_bufobj->bo_object));
|
|
}
|
|
|
|
allocbuf(bp, size);
|
|
|
|
splx(s);
|
|
bp->b_flags &= ~B_DONE;
|
|
}
|
|
KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp));
|
|
KASSERT(bp->b_bufobj == bo,
|
|
("wrong b_bufobj %p should be %p", bp->b_bufobj, bo));
|
|
return (bp);
|
|
}
|
|
|
|
/*
|
|
* Get an empty, disassociated buffer of given size. The buffer is initially
|
|
* set to B_INVAL.
|
|
*/
|
|
struct buf *
|
|
geteblk(int size)
|
|
{
|
|
struct buf *bp;
|
|
int s;
|
|
int maxsize;
|
|
|
|
maxsize = (size + BKVAMASK) & ~BKVAMASK;
|
|
|
|
s = splbio();
|
|
while ((bp = getnewbuf(0, 0, size, maxsize)) == 0)
|
|
continue;
|
|
splx(s);
|
|
allocbuf(bp, size);
|
|
bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
|
|
KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp));
|
|
return (bp);
|
|
}
|
|
|
|
|
|
/*
|
|
* This code constitutes the buffer memory from either anonymous system
|
|
* memory (in the case of non-VMIO operations) or from an associated
|
|
* VM object (in the case of VMIO operations). This code is able to
|
|
* resize a buffer up or down.
|
|
*
|
|
* Note that this code is tricky, and has many complications to resolve
|
|
* deadlock or inconsistant data situations. Tread lightly!!!
|
|
* There are B_CACHE and B_DELWRI interactions that must be dealt with by
|
|
* the caller. Calling this code willy nilly can result in the loss of data.
|
|
*
|
|
* allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
|
|
* B_CACHE for the non-VMIO case.
|
|
*/
|
|
|
|
int
|
|
allocbuf(struct buf *bp, int size)
|
|
{
|
|
int newbsize, mbsize;
|
|
int i;
|
|
|
|
GIANT_REQUIRED;
|
|
|
|
if (BUF_REFCNT(bp) == 0)
|
|
panic("allocbuf: buffer not busy");
|
|
|
|
if (bp->b_kvasize < size)
|
|
panic("allocbuf: buffer too small");
|
|
|
|
if ((bp->b_flags & B_VMIO) == 0) {
|
|
caddr_t origbuf;
|
|
int origbufsize;
|
|
/*
|
|
* Just get anonymous memory from the kernel. Don't
|
|
* mess with B_CACHE.
|
|
*/
|
|
mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
|
|
if (bp->b_flags & B_MALLOC)
|
|
newbsize = mbsize;
|
|
else
|
|
newbsize = round_page(size);
|
|
|
|
if (newbsize < bp->b_bufsize) {
|
|
/*
|
|
* malloced buffers are not shrunk
|
|
*/
|
|
if (bp->b_flags & B_MALLOC) {
|
|
if (newbsize) {
|
|
bp->b_bcount = size;
|
|
} else {
|
|
free(bp->b_data, M_BIOBUF);
|
|
if (bp->b_bufsize) {
|
|
atomic_subtract_int(
|
|
&bufmallocspace,
|
|
bp->b_bufsize);
|
|
bufspacewakeup();
|
|
bp->b_bufsize = 0;
|
|
}
|
|
bp->b_saveaddr = bp->b_kvabase;
|
|
bp->b_data = bp->b_saveaddr;
|
|
bp->b_bcount = 0;
|
|
bp->b_flags &= ~B_MALLOC;
|
|
}
|
|
return 1;
|
|
}
|
|
vm_hold_free_pages(
|
|
bp,
|
|
(vm_offset_t) bp->b_data + newbsize,
|
|
(vm_offset_t) bp->b_data + bp->b_bufsize);
|
|
} else if (newbsize > bp->b_bufsize) {
|
|
/*
|
|
* We only use malloced memory on the first allocation.
|
|
* and revert to page-allocated memory when the buffer
|
|
* grows.
|
|
*/
|
|
/*
|
|
* There is a potential smp race here that could lead
|
|
* to bufmallocspace slightly passing the max. It
|
|
* is probably extremely rare and not worth worrying
|
|
* over.
|
|
*/
|
|
if ( (bufmallocspace < maxbufmallocspace) &&
|
|
(bp->b_bufsize == 0) &&
|
|
(mbsize <= PAGE_SIZE/2)) {
|
|
|
|
bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
|
|
bp->b_bufsize = mbsize;
|
|
bp->b_bcount = size;
|
|
bp->b_flags |= B_MALLOC;
|
|
atomic_add_int(&bufmallocspace, mbsize);
|
|
return 1;
|
|
}
|
|
origbuf = NULL;
|
|
origbufsize = 0;
|
|
/*
|
|
* If the buffer is growing on its other-than-first allocation,
|
|
* then we revert to the page-allocation scheme.
|
|
*/
|
|
if (bp->b_flags & B_MALLOC) {
|
|
origbuf = bp->b_data;
|
|
origbufsize = bp->b_bufsize;
|
|
bp->b_data = bp->b_kvabase;
|
|
if (bp->b_bufsize) {
|
|
atomic_subtract_int(&bufmallocspace,
|
|
bp->b_bufsize);
|
|
bufspacewakeup();
|
|
bp->b_bufsize = 0;
|
|
}
|
|
bp->b_flags &= ~B_MALLOC;
|
|
newbsize = round_page(newbsize);
|
|
}
|
|
vm_hold_load_pages(
|
|
bp,
|
|
(vm_offset_t) bp->b_data + bp->b_bufsize,
|
|
(vm_offset_t) bp->b_data + newbsize);
|
|
if (origbuf) {
|
|
bcopy(origbuf, bp->b_data, origbufsize);
|
|
free(origbuf, M_BIOBUF);
|
|
}
|
|
}
|
|
} else {
|
|
int desiredpages;
|
|
|
|
newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
|
|
desiredpages = (size == 0) ? 0 :
|
|
num_pages((bp->b_offset & PAGE_MASK) + newbsize);
|
|
|
|
if (bp->b_flags & B_MALLOC)
|
|
panic("allocbuf: VMIO buffer can't be malloced");
|
|
/*
|
|
* Set B_CACHE initially if buffer is 0 length or will become
|
|
* 0-length.
|
|
*/
|
|
if (size == 0 || bp->b_bufsize == 0)
|
|
bp->b_flags |= B_CACHE;
|
|
|
|
if (newbsize < bp->b_bufsize) {
|
|
/*
|
|
* DEV_BSIZE aligned new buffer size is less then the
|
|
* DEV_BSIZE aligned existing buffer size. Figure out
|
|
* if we have to remove any pages.
|
|
*/
|
|
if (desiredpages < bp->b_npages) {
|
|
vm_page_t m;
|
|
|
|
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
|
|
vm_page_lock_queues();
|
|
for (i = desiredpages; i < bp->b_npages; i++) {
|
|
/*
|
|
* the page is not freed here -- it
|
|
* is the responsibility of
|
|
* vnode_pager_setsize
|
|
*/
|
|
m = bp->b_pages[i];
|
|
KASSERT(m != bogus_page,
|
|
("allocbuf: bogus page found"));
|
|
while (vm_page_sleep_if_busy(m, TRUE, "biodep"))
|
|
vm_page_lock_queues();
|
|
|
|
bp->b_pages[i] = NULL;
|
|
vm_page_unwire(m, 0);
|
|
}
|
|
vm_page_unlock_queues();
|
|
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
|
|
pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
|
|
(desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
|
|
bp->b_npages = desiredpages;
|
|
}
|
|
} else if (size > bp->b_bcount) {
|
|
/*
|
|
* We are growing the buffer, possibly in a
|
|
* byte-granular fashion.
|
|
*/
|
|
struct vnode *vp;
|
|
vm_object_t obj;
|
|
vm_offset_t toff;
|
|
vm_offset_t tinc;
|
|
|
|
/*
|
|
* Step 1, bring in the VM pages from the object,
|
|
* allocating them if necessary. We must clear
|
|
* B_CACHE if these pages are not valid for the
|
|
* range covered by the buffer.
|
|
*/
|
|
|
|
vp = bp->b_vp;
|
|
obj = bp->b_bufobj->bo_object;
|
|
|
|
VM_OBJECT_LOCK(obj);
|
|
while (bp->b_npages < desiredpages) {
|
|
vm_page_t m;
|
|
vm_pindex_t pi;
|
|
|
|
pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
|
|
if ((m = vm_page_lookup(obj, pi)) == NULL) {
|
|
/*
|
|
* note: must allocate system pages
|
|
* since blocking here could intefere
|
|
* with paging I/O, no matter which
|
|
* process we are.
|
|
*/
|
|
m = vm_page_alloc(obj, pi,
|
|
VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
|
|
VM_ALLOC_WIRED);
|
|
if (m == NULL) {
|
|
atomic_add_int(&vm_pageout_deficit,
|
|
desiredpages - bp->b_npages);
|
|
VM_OBJECT_UNLOCK(obj);
|
|
VM_WAIT;
|
|
VM_OBJECT_LOCK(obj);
|
|
} else {
|
|
bp->b_flags &= ~B_CACHE;
|
|
bp->b_pages[bp->b_npages] = m;
|
|
++bp->b_npages;
|
|
}
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* We found a page. If we have to sleep on it,
|
|
* retry because it might have gotten freed out
|
|
* from under us.
|
|
*
|
|
* We can only test PG_BUSY here. Blocking on
|
|
* m->busy might lead to a deadlock:
|
|
*
|
|
* vm_fault->getpages->cluster_read->allocbuf
|
|
*
|
|
*/
|
|
vm_page_lock_queues();
|
|
if (vm_page_sleep_if_busy(m, FALSE, "pgtblk"))
|
|
continue;
|
|
|
|
/*
|
|
* We have a good page. Should we wakeup the
|
|
* page daemon?
|
|
*/
|
|
if ((curproc != pageproc) &&
|
|
((m->queue - m->pc) == PQ_CACHE) &&
|
|
((cnt.v_free_count + cnt.v_cache_count) <
|
|
(cnt.v_free_min + cnt.v_cache_min))) {
|
|
pagedaemon_wakeup();
|
|
}
|
|
vm_page_wire(m);
|
|
vm_page_unlock_queues();
|
|
bp->b_pages[bp->b_npages] = m;
|
|
++bp->b_npages;
|
|
}
|
|
|
|
/*
|
|
* Step 2. We've loaded the pages into the buffer,
|
|
* we have to figure out if we can still have B_CACHE
|
|
* set. Note that B_CACHE is set according to the
|
|
* byte-granular range ( bcount and size ), new the
|
|
* aligned range ( newbsize ).
|
|
*
|
|
* The VM test is against m->valid, which is DEV_BSIZE
|
|
* aligned. Needless to say, the validity of the data
|
|
* needs to also be DEV_BSIZE aligned. Note that this
|
|
* fails with NFS if the server or some other client
|
|
* extends the file's EOF. If our buffer is resized,
|
|
* B_CACHE may remain set! XXX
|
|
*/
|
|
|
|
toff = bp->b_bcount;
|
|
tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK);
|
|
|
|
while ((bp->b_flags & B_CACHE) && toff < size) {
|
|
vm_pindex_t pi;
|
|
|
|
if (tinc > (size - toff))
|
|
tinc = size - toff;
|
|
|
|
pi = ((bp->b_offset & PAGE_MASK) + toff) >>
|
|
PAGE_SHIFT;
|
|
|
|
vfs_buf_test_cache(
|
|
bp,
|
|
bp->b_offset,
|
|
toff,
|
|
tinc,
|
|
bp->b_pages[pi]
|
|
);
|
|
toff += tinc;
|
|
tinc = PAGE_SIZE;
|
|
}
|
|
VM_OBJECT_UNLOCK(obj);
|
|
|
|
/*
|
|
* Step 3, fixup the KVM pmap. Remember that
|
|
* bp->b_data is relative to bp->b_offset, but
|
|
* bp->b_offset may be offset into the first page.
|
|
*/
|
|
|
|
bp->b_data = (caddr_t)
|
|
trunc_page((vm_offset_t)bp->b_data);
|
|
pmap_qenter(
|
|
(vm_offset_t)bp->b_data,
|
|
bp->b_pages,
|
|
bp->b_npages
|
|
);
|
|
|
|
bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
|
|
(vm_offset_t)(bp->b_offset & PAGE_MASK));
|
|
}
|
|
}
|
|
if (newbsize < bp->b_bufsize)
|
|
bufspacewakeup();
|
|
bp->b_bufsize = newbsize; /* actual buffer allocation */
|
|
bp->b_bcount = size; /* requested buffer size */
|
|
return 1;
|
|
}
|
|
|
|
void
|
|
biodone(struct bio *bp)
|
|
{
|
|
|
|
mtx_lock(&bdonelock);
|
|
bp->bio_flags |= BIO_DONE;
|
|
if (bp->bio_done == NULL)
|
|
wakeup(bp);
|
|
mtx_unlock(&bdonelock);
|
|
if (bp->bio_done != NULL)
|
|
bp->bio_done(bp);
|
|
}
|
|
|
|
/*
|
|
* Wait for a BIO to finish.
|
|
*
|
|
* XXX: resort to a timeout for now. The optimal locking (if any) for this
|
|
* case is not yet clear.
|
|
*/
|
|
int
|
|
biowait(struct bio *bp, const char *wchan)
|
|
{
|
|
|
|
mtx_lock(&bdonelock);
|
|
while ((bp->bio_flags & BIO_DONE) == 0)
|
|
msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10);
|
|
mtx_unlock(&bdonelock);
|
|
if (bp->bio_error != 0)
|
|
return (bp->bio_error);
|
|
if (!(bp->bio_flags & BIO_ERROR))
|
|
return (0);
|
|
return (EIO);
|
|
}
|
|
|
|
void
|
|
biofinish(struct bio *bp, struct devstat *stat, int error)
|
|
{
|
|
|
|
if (error) {
|
|
bp->bio_error = error;
|
|
bp->bio_flags |= BIO_ERROR;
|
|
}
|
|
if (stat != NULL)
|
|
devstat_end_transaction_bio(stat, bp);
|
|
biodone(bp);
|
|
}
|
|
|
|
/*
|
|
* bufwait:
|
|
*
|
|
* Wait for buffer I/O completion, returning error status. The buffer
|
|
* is left locked and B_DONE on return. B_EINTR is converted into an EINTR
|
|
* error and cleared.
|
|
*/
|
|
int
|
|
bufwait(struct buf *bp)
|
|
{
|
|
int s;
|
|
|
|
s = splbio();
|
|
if (bp->b_iocmd == BIO_READ)
|
|
bwait(bp, PRIBIO, "biord");
|
|
else
|
|
bwait(bp, PRIBIO, "biowr");
|
|
splx(s);
|
|
if (bp->b_flags & B_EINTR) {
|
|
bp->b_flags &= ~B_EINTR;
|
|
return (EINTR);
|
|
}
|
|
if (bp->b_ioflags & BIO_ERROR) {
|
|
return (bp->b_error ? bp->b_error : EIO);
|
|
} else {
|
|
return (0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Call back function from struct bio back up to struct buf.
|
|
*/
|
|
static void
|
|
bufdonebio(struct bio *bip)
|
|
{
|
|
struct buf *bp;
|
|
|
|
/* Device drivers may or may not hold giant, hold it here. */
|
|
mtx_lock(&Giant);
|
|
bp = bip->bio_caller2;
|
|
bp->b_resid = bp->b_bcount - bip->bio_completed;
|
|
bp->b_resid = bip->bio_resid; /* XXX: remove */
|
|
bp->b_ioflags = bip->bio_flags;
|
|
bp->b_error = bip->bio_error;
|
|
if (bp->b_error)
|
|
bp->b_ioflags |= BIO_ERROR;
|
|
bufdone(bp);
|
|
mtx_unlock(&Giant);
|
|
g_destroy_bio(bip);
|
|
}
|
|
|
|
void
|
|
dev_strategy(struct cdev *dev, struct buf *bp)
|
|
{
|
|
struct cdevsw *csw;
|
|
struct bio *bip;
|
|
|
|
if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
|
|
panic("b_iocmd botch");
|
|
for (;;) {
|
|
bip = g_new_bio();
|
|
if (bip != NULL)
|
|
break;
|
|
/* Try again later */
|
|
tsleep(&bp, PRIBIO, "dev_strat", hz/10);
|
|
}
|
|
bip->bio_cmd = bp->b_iocmd;
|
|
bip->bio_offset = bp->b_iooffset;
|
|
bip->bio_length = bp->b_bcount;
|
|
bip->bio_bcount = bp->b_bcount; /* XXX: remove */
|
|
bip->bio_data = bp->b_data;
|
|
bip->bio_done = bufdonebio;
|
|
bip->bio_caller2 = bp;
|
|
bip->bio_dev = dev;
|
|
KASSERT(dev->si_refcount > 0,
|
|
("dev_strategy on un-referenced struct cdev *(%s)",
|
|
devtoname(dev)));
|
|
csw = dev_refthread(dev);
|
|
if (csw == NULL) {
|
|
bp->b_error = ENXIO;
|
|
bp->b_ioflags = BIO_ERROR;
|
|
mtx_lock(&Giant); /* XXX: too defensive ? */
|
|
bufdone(bp);
|
|
mtx_unlock(&Giant); /* XXX: too defensive ? */
|
|
return;
|
|
}
|
|
(*csw->d_strategy)(bip);
|
|
dev_relthread(dev);
|
|
}
|
|
|
|
/*
|
|
* bufdone:
|
|
*
|
|
* Finish I/O on a buffer, optionally calling a completion function.
|
|
* This is usually called from an interrupt so process blocking is
|
|
* not allowed.
|
|
*
|
|
* biodone is also responsible for setting B_CACHE in a B_VMIO bp.
|
|
* In a non-VMIO bp, B_CACHE will be set on the next getblk()
|
|
* assuming B_INVAL is clear.
|
|
*
|
|
* For the VMIO case, we set B_CACHE if the op was a read and no
|
|
* read error occured, or if the op was a write. B_CACHE is never
|
|
* set if the buffer is invalid or otherwise uncacheable.
|
|
*
|
|
* biodone does not mess with B_INVAL, allowing the I/O routine or the
|
|
* initiator to leave B_INVAL set to brelse the buffer out of existance
|
|
* in the biodone routine.
|
|
*/
|
|
void
|
|
bufdone(struct buf *bp)
|
|
{
|
|
int s;
|
|
void (*biodone)(struct buf *);
|
|
|
|
|
|
s = splbio();
|
|
|
|
KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNT(bp)));
|
|
KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
|
|
|
|
bp->b_flags |= B_DONE;
|
|
runningbufwakeup(bp);
|
|
|
|
if (bp->b_iocmd == BIO_WRITE && bp->b_bufobj != NULL)
|
|
bufobj_wdrop(bp->b_bufobj);
|
|
|
|
/* call optional completion function if requested */
|
|
if (bp->b_iodone != NULL) {
|
|
biodone = bp->b_iodone;
|
|
bp->b_iodone = NULL;
|
|
(*biodone) (bp);
|
|
splx(s);
|
|
return;
|
|
}
|
|
if (LIST_FIRST(&bp->b_dep) != NULL)
|
|
buf_complete(bp);
|
|
|
|
if (bp->b_flags & B_VMIO) {
|
|
int i;
|
|
vm_ooffset_t foff;
|
|
vm_page_t m;
|
|
vm_object_t obj;
|
|
int iosize;
|
|
struct vnode *vp = bp->b_vp;
|
|
|
|
obj = bp->b_bufobj->bo_object;
|
|
|
|
#if defined(VFS_BIO_DEBUG)
|
|
mp_fixme("usecount and vflag accessed without locks.");
|
|
if (vp->v_usecount == 0) {
|
|
panic("biodone: zero vnode ref count");
|
|
}
|
|
|
|
if ((vp->v_vflag & VV_OBJBUF) == 0) {
|
|
panic("biodone: vnode is not setup for merged cache");
|
|
}
|
|
#endif
|
|
|
|
foff = bp->b_offset;
|
|
KASSERT(bp->b_offset != NOOFFSET,
|
|
("biodone: no buffer offset"));
|
|
|
|
VM_OBJECT_LOCK(obj);
|
|
#if defined(VFS_BIO_DEBUG)
|
|
if (obj->paging_in_progress < bp->b_npages) {
|
|
printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
|
|
obj->paging_in_progress, bp->b_npages);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Set B_CACHE if the op was a normal read and no error
|
|
* occured. B_CACHE is set for writes in the b*write()
|
|
* routines.
|
|
*/
|
|
iosize = bp->b_bcount - bp->b_resid;
|
|
if (bp->b_iocmd == BIO_READ &&
|
|
!(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
|
|
!(bp->b_ioflags & BIO_ERROR)) {
|
|
bp->b_flags |= B_CACHE;
|
|
}
|
|
vm_page_lock_queues();
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
int bogusflag = 0;
|
|
int resid;
|
|
|
|
resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
|
|
if (resid > iosize)
|
|
resid = iosize;
|
|
|
|
/*
|
|
* cleanup bogus pages, restoring the originals
|
|
*/
|
|
m = bp->b_pages[i];
|
|
if (m == bogus_page) {
|
|
bogusflag = 1;
|
|
m = vm_page_lookup(obj, OFF_TO_IDX(foff));
|
|
if (m == NULL)
|
|
panic("biodone: page disappeared!");
|
|
bp->b_pages[i] = m;
|
|
pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
|
|
}
|
|
#if defined(VFS_BIO_DEBUG)
|
|
if (OFF_TO_IDX(foff) != m->pindex) {
|
|
printf(
|
|
"biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
|
|
(intmax_t)foff, (uintmax_t)m->pindex);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* In the write case, the valid and clean bits are
|
|
* already changed correctly ( see bdwrite() ), so we
|
|
* only need to do this here in the read case.
|
|
*/
|
|
if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
|
|
vfs_page_set_valid(bp, foff, i, m);
|
|
}
|
|
|
|
/*
|
|
* when debugging new filesystems or buffer I/O methods, this
|
|
* is the most common error that pops up. if you see this, you
|
|
* have not set the page busy flag correctly!!!
|
|
*/
|
|
if (m->busy == 0) {
|
|
printf("biodone: page busy < 0, "
|
|
"pindex: %d, foff: 0x(%x,%x), "
|
|
"resid: %d, index: %d\n",
|
|
(int) m->pindex, (int)(foff >> 32),
|
|
(int) foff & 0xffffffff, resid, i);
|
|
if (!vn_isdisk(vp, NULL))
|
|
printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
|
|
(intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
|
|
(intmax_t) bp->b_lblkno,
|
|
bp->b_flags, bp->b_npages);
|
|
else
|
|
printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
|
|
(intmax_t) bp->b_lblkno,
|
|
bp->b_flags, bp->b_npages);
|
|
printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
|
|
(u_long)m->valid, (u_long)m->dirty,
|
|
m->wire_count);
|
|
panic("biodone: page busy < 0\n");
|
|
}
|
|
vm_page_io_finish(m);
|
|
vm_object_pip_subtract(obj, 1);
|
|
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
|
|
iosize -= resid;
|
|
}
|
|
vm_page_unlock_queues();
|
|
vm_object_pip_wakeupn(obj, 0);
|
|
VM_OBJECT_UNLOCK(obj);
|
|
}
|
|
|
|
/*
|
|
* For asynchronous completions, release the buffer now. The brelse
|
|
* will do a wakeup there if necessary - so no need to do a wakeup
|
|
* here in the async case. The sync case always needs to do a wakeup.
|
|
*/
|
|
|
|
if (bp->b_flags & B_ASYNC) {
|
|
if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
|
|
brelse(bp);
|
|
else
|
|
bqrelse(bp);
|
|
} else {
|
|
bdone(bp);
|
|
}
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* This routine is called in lieu of iodone in the case of
|
|
* incomplete I/O. This keeps the busy status for pages
|
|
* consistant.
|
|
*/
|
|
void
|
|
vfs_unbusy_pages(struct buf *bp)
|
|
{
|
|
int i;
|
|
vm_object_t obj;
|
|
vm_page_t m;
|
|
|
|
runningbufwakeup(bp);
|
|
if (!(bp->b_flags & B_VMIO))
|
|
return;
|
|
|
|
obj = bp->b_bufobj->bo_object;
|
|
VM_OBJECT_LOCK(obj);
|
|
vm_page_lock_queues();
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
m = bp->b_pages[i];
|
|
if (m == bogus_page) {
|
|
m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
|
|
if (!m)
|
|
panic("vfs_unbusy_pages: page missing\n");
|
|
bp->b_pages[i] = m;
|
|
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
|
|
bp->b_pages, bp->b_npages);
|
|
}
|
|
vm_object_pip_subtract(obj, 1);
|
|
vm_page_io_finish(m);
|
|
}
|
|
vm_page_unlock_queues();
|
|
vm_object_pip_wakeupn(obj, 0);
|
|
VM_OBJECT_UNLOCK(obj);
|
|
}
|
|
|
|
/*
|
|
* vfs_page_set_valid:
|
|
*
|
|
* Set the valid bits in a page based on the supplied offset. The
|
|
* range is restricted to the buffer's size.
|
|
*
|
|
* This routine is typically called after a read completes.
|
|
*/
|
|
static void
|
|
vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m)
|
|
{
|
|
vm_ooffset_t soff, eoff;
|
|
|
|
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
|
|
/*
|
|
* Start and end offsets in buffer. eoff - soff may not cross a
|
|
* page boundry or cross the end of the buffer. The end of the
|
|
* buffer, in this case, is our file EOF, not the allocation size
|
|
* of the buffer.
|
|
*/
|
|
soff = off;
|
|
eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
|
|
if (eoff > bp->b_offset + bp->b_bcount)
|
|
eoff = bp->b_offset + bp->b_bcount;
|
|
|
|
/*
|
|
* Set valid range. This is typically the entire buffer and thus the
|
|
* entire page.
|
|
*/
|
|
if (eoff > soff) {
|
|
vm_page_set_validclean(
|
|
m,
|
|
(vm_offset_t) (soff & PAGE_MASK),
|
|
(vm_offset_t) (eoff - soff)
|
|
);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This routine is called before a device strategy routine.
|
|
* It is used to tell the VM system that paging I/O is in
|
|
* progress, and treat the pages associated with the buffer
|
|
* almost as being PG_BUSY. Also the object paging_in_progress
|
|
* flag is handled to make sure that the object doesn't become
|
|
* inconsistant.
|
|
*
|
|
* Since I/O has not been initiated yet, certain buffer flags
|
|
* such as BIO_ERROR or B_INVAL may be in an inconsistant state
|
|
* and should be ignored.
|
|
*/
|
|
void
|
|
vfs_busy_pages(struct buf *bp, int clear_modify)
|
|
{
|
|
int i, bogus;
|
|
vm_object_t obj;
|
|
vm_ooffset_t foff;
|
|
vm_page_t m;
|
|
|
|
if (!(bp->b_flags & B_VMIO))
|
|
return;
|
|
|
|
obj = bp->b_bufobj->bo_object;
|
|
foff = bp->b_offset;
|
|
KASSERT(bp->b_offset != NOOFFSET,
|
|
("vfs_busy_pages: no buffer offset"));
|
|
vfs_setdirty(bp);
|
|
VM_OBJECT_LOCK(obj);
|
|
retry:
|
|
vm_page_lock_queues();
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
m = bp->b_pages[i];
|
|
|
|
if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
|
|
goto retry;
|
|
}
|
|
bogus = 0;
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
m = bp->b_pages[i];
|
|
|
|
if ((bp->b_flags & B_CLUSTER) == 0) {
|
|
vm_object_pip_add(obj, 1);
|
|
vm_page_io_start(m);
|
|
}
|
|
/*
|
|
* When readying a buffer for a read ( i.e
|
|
* clear_modify == 0 ), it is important to do
|
|
* bogus_page replacement for valid pages in
|
|
* partially instantiated buffers. Partially
|
|
* instantiated buffers can, in turn, occur when
|
|
* reconstituting a buffer from its VM backing store
|
|
* base. We only have to do this if B_CACHE is
|
|
* clear ( which causes the I/O to occur in the
|
|
* first place ). The replacement prevents the read
|
|
* I/O from overwriting potentially dirty VM-backed
|
|
* pages. XXX bogus page replacement is, uh, bogus.
|
|
* It may not work properly with small-block devices.
|
|
* We need to find a better way.
|
|
*/
|
|
pmap_remove_all(m);
|
|
if (clear_modify)
|
|
vfs_page_set_valid(bp, foff, i, m);
|
|
else if (m->valid == VM_PAGE_BITS_ALL &&
|
|
(bp->b_flags & B_CACHE) == 0) {
|
|
bp->b_pages[i] = bogus_page;
|
|
bogus++;
|
|
}
|
|
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
|
|
}
|
|
vm_page_unlock_queues();
|
|
VM_OBJECT_UNLOCK(obj);
|
|
if (bogus)
|
|
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
|
|
bp->b_pages, bp->b_npages);
|
|
}
|
|
|
|
/*
|
|
* Tell the VM system that the pages associated with this buffer
|
|
* are clean. This is used for delayed writes where the data is
|
|
* going to go to disk eventually without additional VM intevention.
|
|
*
|
|
* Note that while we only really need to clean through to b_bcount, we
|
|
* just go ahead and clean through to b_bufsize.
|
|
*/
|
|
static void
|
|
vfs_clean_pages(struct buf *bp)
|
|
{
|
|
int i;
|
|
vm_ooffset_t foff, noff, eoff;
|
|
vm_page_t m;
|
|
|
|
if (!(bp->b_flags & B_VMIO))
|
|
return;
|
|
|
|
foff = bp->b_offset;
|
|
KASSERT(bp->b_offset != NOOFFSET,
|
|
("vfs_clean_pages: no buffer offset"));
|
|
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
|
|
vm_page_lock_queues();
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
m = bp->b_pages[i];
|
|
noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
|
|
eoff = noff;
|
|
|
|
if (eoff > bp->b_offset + bp->b_bufsize)
|
|
eoff = bp->b_offset + bp->b_bufsize;
|
|
vfs_page_set_valid(bp, foff, i, m);
|
|
/* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
|
|
foff = noff;
|
|
}
|
|
vm_page_unlock_queues();
|
|
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
|
|
}
|
|
|
|
/*
|
|
* vfs_bio_set_validclean:
|
|
*
|
|
* Set the range within the buffer to valid and clean. The range is
|
|
* relative to the beginning of the buffer, b_offset. Note that b_offset
|
|
* itself may be offset from the beginning of the first page.
|
|
*
|
|
*/
|
|
|
|
void
|
|
vfs_bio_set_validclean(struct buf *bp, int base, int size)
|
|
{
|
|
int i, n;
|
|
vm_page_t m;
|
|
|
|
if (!(bp->b_flags & B_VMIO))
|
|
return;
|
|
/*
|
|
* Fixup base to be relative to beginning of first page.
|
|
* Set initial n to be the maximum number of bytes in the
|
|
* first page that can be validated.
|
|
*/
|
|
|
|
base += (bp->b_offset & PAGE_MASK);
|
|
n = PAGE_SIZE - (base & PAGE_MASK);
|
|
|
|
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
|
|
vm_page_lock_queues();
|
|
for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
|
|
m = bp->b_pages[i];
|
|
if (n > size)
|
|
n = size;
|
|
vm_page_set_validclean(m, base & PAGE_MASK, n);
|
|
base += n;
|
|
size -= n;
|
|
n = PAGE_SIZE;
|
|
}
|
|
vm_page_unlock_queues();
|
|
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
|
|
}
|
|
|
|
/*
|
|
* vfs_bio_clrbuf:
|
|
*
|
|
* clear a buffer. This routine essentially fakes an I/O, so we need
|
|
* to clear BIO_ERROR and B_INVAL.
|
|
*
|
|
* Note that while we only theoretically need to clear through b_bcount,
|
|
* we go ahead and clear through b_bufsize.
|
|
*/
|
|
|
|
void
|
|
vfs_bio_clrbuf(struct buf *bp)
|
|
{
|
|
int i, j, mask = 0;
|
|
caddr_t sa, ea;
|
|
|
|
GIANT_REQUIRED;
|
|
|
|
if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
|
|
clrbuf(bp);
|
|
return;
|
|
}
|
|
|
|
bp->b_flags &= ~B_INVAL;
|
|
bp->b_ioflags &= ~BIO_ERROR;
|
|
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
|
|
if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
|
|
(bp->b_offset & PAGE_MASK) == 0) {
|
|
if (bp->b_pages[0] == bogus_page)
|
|
goto unlock;
|
|
mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
|
|
VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
|
|
if ((bp->b_pages[0]->valid & mask) == mask)
|
|
goto unlock;
|
|
if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
|
|
((bp->b_pages[0]->valid & mask) == 0)) {
|
|
bzero(bp->b_data, bp->b_bufsize);
|
|
bp->b_pages[0]->valid |= mask;
|
|
goto unlock;
|
|
}
|
|
}
|
|
ea = sa = bp->b_data;
|
|
for(i = 0; i < bp->b_npages; i++, sa = ea) {
|
|
ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
|
|
ea = (caddr_t)(vm_offset_t)ulmin(
|
|
(u_long)(vm_offset_t)ea,
|
|
(u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
|
|
if (bp->b_pages[i] == bogus_page)
|
|
continue;
|
|
j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
|
|
mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
|
|
VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
|
|
if ((bp->b_pages[i]->valid & mask) == mask)
|
|
continue;
|
|
if ((bp->b_pages[i]->valid & mask) == 0) {
|
|
if ((bp->b_pages[i]->flags & PG_ZERO) == 0)
|
|
bzero(sa, ea - sa);
|
|
} else {
|
|
for (; sa < ea; sa += DEV_BSIZE, j++) {
|
|
if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
|
|
(bp->b_pages[i]->valid & (1 << j)) == 0)
|
|
bzero(sa, DEV_BSIZE);
|
|
}
|
|
}
|
|
bp->b_pages[i]->valid |= mask;
|
|
}
|
|
unlock:
|
|
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
|
|
bp->b_resid = 0;
|
|
}
|
|
|
|
/*
|
|
* vm_hold_load_pages and vm_hold_free_pages get pages into
|
|
* a buffers address space. The pages are anonymous and are
|
|
* not associated with a file object.
|
|
*/
|
|
static void
|
|
vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
|
|
{
|
|
vm_offset_t pg;
|
|
vm_page_t p;
|
|
int index;
|
|
|
|
to = round_page(to);
|
|
from = round_page(from);
|
|
index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
|
|
|
|
VM_OBJECT_LOCK(kernel_object);
|
|
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
|
|
tryagain:
|
|
/*
|
|
* note: must allocate system pages since blocking here
|
|
* could intefere with paging I/O, no matter which
|
|
* process we are.
|
|
*/
|
|
p = vm_page_alloc(kernel_object,
|
|
((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
|
|
VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
|
|
if (!p) {
|
|
atomic_add_int(&vm_pageout_deficit,
|
|
(to - pg) >> PAGE_SHIFT);
|
|
VM_OBJECT_UNLOCK(kernel_object);
|
|
VM_WAIT;
|
|
VM_OBJECT_LOCK(kernel_object);
|
|
goto tryagain;
|
|
}
|
|
p->valid = VM_PAGE_BITS_ALL;
|
|
pmap_qenter(pg, &p, 1);
|
|
bp->b_pages[index] = p;
|
|
}
|
|
VM_OBJECT_UNLOCK(kernel_object);
|
|
bp->b_npages = index;
|
|
}
|
|
|
|
/* Return pages associated with this buf to the vm system */
|
|
static void
|
|
vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
|
|
{
|
|
vm_offset_t pg;
|
|
vm_page_t p;
|
|
int index, newnpages;
|
|
|
|
from = round_page(from);
|
|
to = round_page(to);
|
|
newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
|
|
|
|
VM_OBJECT_LOCK(kernel_object);
|
|
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
|
|
p = bp->b_pages[index];
|
|
if (p && (index < bp->b_npages)) {
|
|
if (p->busy) {
|
|
printf(
|
|
"vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
|
|
(intmax_t)bp->b_blkno,
|
|
(intmax_t)bp->b_lblkno);
|
|
}
|
|
bp->b_pages[index] = NULL;
|
|
pmap_qremove(pg, 1);
|
|
vm_page_lock_queues();
|
|
vm_page_unwire(p, 0);
|
|
vm_page_free(p);
|
|
vm_page_unlock_queues();
|
|
}
|
|
}
|
|
VM_OBJECT_UNLOCK(kernel_object);
|
|
bp->b_npages = newnpages;
|
|
}
|
|
|
|
/*
|
|
* Map an IO request into kernel virtual address space.
|
|
*
|
|
* All requests are (re)mapped into kernel VA space.
|
|
* Notice that we use b_bufsize for the size of the buffer
|
|
* to be mapped. b_bcount might be modified by the driver.
|
|
*
|
|
* Note that even if the caller determines that the address space should
|
|
* be valid, a race or a smaller-file mapped into a larger space may
|
|
* actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
|
|
* check the return value.
|
|
*/
|
|
int
|
|
vmapbuf(struct buf *bp)
|
|
{
|
|
caddr_t addr, kva;
|
|
vm_prot_t prot;
|
|
int pidx, i;
|
|
struct vm_page *m;
|
|
struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
|
|
|
|
if (bp->b_bufsize < 0)
|
|
return (-1);
|
|
prot = VM_PROT_READ;
|
|
if (bp->b_iocmd == BIO_READ)
|
|
prot |= VM_PROT_WRITE; /* Less backwards than it looks */
|
|
for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
|
|
addr < bp->b_data + bp->b_bufsize;
|
|
addr += PAGE_SIZE, pidx++) {
|
|
/*
|
|
* Do the vm_fault if needed; do the copy-on-write thing
|
|
* when reading stuff off device into memory.
|
|
*
|
|
* NOTE! Must use pmap_extract() because addr may be in
|
|
* the userland address space, and kextract is only guarenteed
|
|
* to work for the kernland address space (see: sparc64 port).
|
|
*/
|
|
retry:
|
|
if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
|
|
prot) < 0) {
|
|
vm_page_lock_queues();
|
|
for (i = 0; i < pidx; ++i) {
|
|
vm_page_unhold(bp->b_pages[i]);
|
|
bp->b_pages[i] = NULL;
|
|
}
|
|
vm_page_unlock_queues();
|
|
return(-1);
|
|
}
|
|
m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
|
|
if (m == NULL)
|
|
goto retry;
|
|
bp->b_pages[pidx] = m;
|
|
}
|
|
if (pidx > btoc(MAXPHYS))
|
|
panic("vmapbuf: mapped more than MAXPHYS");
|
|
pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
|
|
|
|
kva = bp->b_saveaddr;
|
|
bp->b_npages = pidx;
|
|
bp->b_saveaddr = bp->b_data;
|
|
bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
|
|
return(0);
|
|
}
|
|
|
|
/*
|
|
* Free the io map PTEs associated with this IO operation.
|
|
* We also invalidate the TLB entries and restore the original b_addr.
|
|
*/
|
|
void
|
|
vunmapbuf(struct buf *bp)
|
|
{
|
|
int pidx;
|
|
int npages;
|
|
|
|
npages = bp->b_npages;
|
|
pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
|
|
vm_page_lock_queues();
|
|
for (pidx = 0; pidx < npages; pidx++)
|
|
vm_page_unhold(bp->b_pages[pidx]);
|
|
vm_page_unlock_queues();
|
|
|
|
bp->b_data = bp->b_saveaddr;
|
|
}
|
|
|
|
void
|
|
bdone(struct buf *bp)
|
|
{
|
|
|
|
mtx_lock(&bdonelock);
|
|
bp->b_flags |= B_DONE;
|
|
wakeup(bp);
|
|
mtx_unlock(&bdonelock);
|
|
}
|
|
|
|
void
|
|
bwait(struct buf *bp, u_char pri, const char *wchan)
|
|
{
|
|
|
|
mtx_lock(&bdonelock);
|
|
while ((bp->b_flags & B_DONE) == 0)
|
|
msleep(bp, &bdonelock, pri, wchan, 0);
|
|
mtx_unlock(&bdonelock);
|
|
}
|
|
|
|
int
|
|
bufsync(struct bufobj *bo, int waitfor, struct thread *td)
|
|
{
|
|
|
|
return (VOP_FSYNC(bo->__bo_vnode, waitfor, td));
|
|
}
|
|
|
|
void
|
|
bufstrategy(struct bufobj *bo, struct buf *bp)
|
|
{
|
|
int i = 0;
|
|
struct vnode *vp;
|
|
|
|
vp = bp->b_vp;
|
|
KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
|
|
KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
|
|
("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
|
|
i = VOP_STRATEGY(vp, bp);
|
|
KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
|
|
}
|
|
|
|
void
|
|
bufobj_wref(struct bufobj *bo)
|
|
{
|
|
|
|
KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
|
|
BO_LOCK(bo);
|
|
bo->bo_numoutput++;
|
|
BO_UNLOCK(bo);
|
|
}
|
|
|
|
void
|
|
bufobj_wdrop(struct bufobj *bo)
|
|
{
|
|
|
|
KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
|
|
BO_LOCK(bo);
|
|
KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
|
|
if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
|
|
bo->bo_flag &= ~BO_WWAIT;
|
|
wakeup(&bo->bo_numoutput);
|
|
}
|
|
BO_UNLOCK(bo);
|
|
}
|
|
|
|
int
|
|
bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
|
|
{
|
|
int error;
|
|
|
|
KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
|
|
ASSERT_BO_LOCKED(bo);
|
|
error = 0;
|
|
while (bo->bo_numoutput) {
|
|
bo->bo_flag |= BO_WWAIT;
|
|
error = msleep(&bo->bo_numoutput, BO_MTX(bo),
|
|
slpflag | (PRIBIO + 1), "bo_wwait", timeo);
|
|
if (error)
|
|
break;
|
|
}
|
|
return (error);
|
|
}
|
|
|
|
#include "opt_ddb.h"
|
|
#ifdef DDB
|
|
#include <ddb/ddb.h>
|
|
|
|
/* DDB command to show buffer data */
|
|
DB_SHOW_COMMAND(buffer, db_show_buffer)
|
|
{
|
|
/* get args */
|
|
struct buf *bp = (struct buf *)addr;
|
|
|
|
if (!have_addr) {
|
|
db_printf("usage: show buffer <addr>\n");
|
|
return;
|
|
}
|
|
|
|
db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
|
|
db_printf(
|
|
"b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
|
|
"b_bufobj = (%p), b_data = %p, b_blkno = %jd\n",
|
|
bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
|
|
bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno);
|
|
if (bp->b_npages) {
|
|
int i;
|
|
db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages);
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
vm_page_t m;
|
|
m = bp->b_pages[i];
|
|
db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object,
|
|
(u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m));
|
|
if ((i + 1) < bp->b_npages)
|
|
db_printf(",");
|
|
}
|
|
db_printf("\n");
|
|
}
|
|
}
|
|
#endif /* DDB */
|