2973 lines
75 KiB
C
2973 lines
75 KiB
C
/*
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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 immediately at the beginning of the file, without modification,
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* this list of conditions, and the following disclaimer.
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* 2. Absolutely no warranty of function or purpose is made by the author
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* John S. Dyson.
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*
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* $Id: vfs_bio.c,v 1.216 1999/06/26 02:46:06 mckusick Exp $
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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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#define VMIO
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/sysproto.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/vmmeter.h>
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#include <sys/lock.h>
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#include <miscfs/specfs/specdev.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_prot.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 <sys/buf.h>
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#include <sys/mount.h>
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#include <sys/malloc.h>
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#include <sys/resourcevar.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 *buf; /* buffer header pool */
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struct swqueue bswlist;
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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 flushdirtybuffers(int slpflag, int slptimeo);
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static int flushbufqueues(void);
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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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int runningbufspace;
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static vm_offset_t bogus_offset;
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static int bufspace, maxbufspace, vmiospace, maxvmiobufspace,
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bufmallocspace, maxbufmallocspace, hibufspace;
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static int needsbuffer;
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static int numdirtybuffers, lodirtybuffers, hidirtybuffers;
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static int numfreebuffers, lofreebuffers, hifreebuffers;
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static int kvafreespace;
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SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD,
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&numdirtybuffers, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW,
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&lodirtybuffers, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW,
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&hidirtybuffers, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD,
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&numfreebuffers, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW,
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&lofreebuffers, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW,
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&hifreebuffers, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD,
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&runningbufspace, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW,
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&maxbufspace, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD,
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&hibufspace, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD,
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&bufspace, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, maxvmiobufspace, CTLFLAG_RW,
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&maxvmiobufspace, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, vmiospace, CTLFLAG_RD,
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&vmiospace, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW,
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&maxbufmallocspace, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD,
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&bufmallocspace, 0, "");
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SYSCTL_INT(_vfs, OID_AUTO, kvafreespace, CTLFLAG_RD,
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&kvafreespace, 0, "");
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static LIST_HEAD(bufhashhdr, buf) bufhashtbl[BUFHSZ], invalhash;
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struct bqueues bufqueues[BUFFER_QUEUES] = { { 0 } };
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char *buf_wmesg = BUF_WMESG;
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extern int vm_swap_size;
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#define BUF_MAXUSE 24
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#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
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#define VFS_BIO_NEED_RESERVED02 0x02 /* unused */
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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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#define VFS_BIO_NEED_KVASPACE 0x10 /* wait for buffer_map space, emerg */
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/*
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* kvaspacewakeup:
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*
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* Called when kva space is potential available for recovery or when
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* kva space is recovered in the buffer_map. This function wakes up
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* anyone waiting for buffer_map kva space. Even though the buffer_map
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* is larger then maxbufspace, this situation will typically occur
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* when the buffer_map gets fragmented.
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*/
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static __inline void
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kvaspacewakeup(void)
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{
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/*
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* If someone is waiting for KVA 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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if (needsbuffer & VFS_BIO_NEED_KVASPACE) {
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needsbuffer &= ~VFS_BIO_NEED_KVASPACE;
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wakeup(&needsbuffer);
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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 or when
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* buffer space is recovered. getnewbuf() will block on this flag when
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* it is unable to free sufficient buffer space. Buffer space becomes
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* recoverable when 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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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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}
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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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++numfreebuffers;
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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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}
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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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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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/*
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* Initialize buffer headers and related structures.
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*/
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void
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bufinit()
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{
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struct buf *bp;
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int i;
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TAILQ_INIT(&bswlist);
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LIST_INIT(&invalhash);
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simple_lock_init(&buftimelock);
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/* first, make a null hash table */
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for (i = 0; i < BUFHSZ; i++)
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LIST_INIT(&bufhashtbl[i]);
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/* next, make a null set of free lists */
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for (i = 0; i < BUFFER_QUEUES; i++)
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TAILQ_INIT(&bufqueues[i]);
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/* finally, initialize each buffer header and stick on empty q */
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for (i = 0; i < nbuf; i++) {
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bp = &buf[i];
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bzero(bp, sizeof *bp);
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bp->b_flags = B_INVAL; /* we're just an empty header */
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bp->b_dev = NODEV;
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bp->b_rcred = NOCRED;
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bp->b_wcred = NOCRED;
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bp->b_qindex = QUEUE_EMPTY;
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bp->b_xflags = 0;
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LIST_INIT(&bp->b_dep);
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BUF_LOCKINIT(bp);
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TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
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LIST_INSERT_HEAD(&invalhash, bp, b_hash);
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}
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/*
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* maxbufspace is currently calculated to support all filesystem
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* blocks to be 8K. If you happen to use a 16K filesystem, the size
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* of the buffer cache is still the same as it would be for 8K
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* filesystems. This keeps the size of the buffer cache "in check"
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* for big block filesystems.
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*
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* maxbufspace is calculated as around 50% of the KVA available in
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* the buffer_map ( DFLTSIZE vs BKVASIZE ), I presume to reduce the
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* effect of fragmentation.
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*/
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maxbufspace = (nbuf + 8) * DFLTBSIZE;
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if ((hibufspace = maxbufspace - MAXBSIZE * 5) <= MAXBSIZE)
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hibufspace = 3 * maxbufspace / 4;
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/*
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* reserve 1/3 of the buffers for metadata (VDIR) which might not be VMIO'ed
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*/
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maxvmiobufspace = 2 * hibufspace / 3;
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/*
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* Limit the amount of malloc memory since it is wired permanently into
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* the kernel space. Even though this is accounted for in the buffer
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* allocation, we don't want the malloced region to grow uncontrolled.
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* The malloc scheme improves memory utilization significantly on average
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* (small) directories.
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*/
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maxbufmallocspace = hibufspace / 20;
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/*
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* Reduce the chance of a deadlock occuring by limiting the number
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* of delayed-write dirty buffers we allow to stack up.
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*/
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lodirtybuffers = nbuf / 16 + 10;
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hidirtybuffers = nbuf / 8 + 20;
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numdirtybuffers = 0;
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/*
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* Try to keep the number of free buffers in the specified range,
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* and give the syncer access to an emergency reserve.
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*/
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lofreebuffers = nbuf / 18 + 5;
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hifreebuffers = 2 * lofreebuffers;
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numfreebuffers = nbuf;
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kvafreespace = 0;
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bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE);
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bogus_page = vm_page_alloc(kernel_object,
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((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
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VM_ALLOC_NORMAL);
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}
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/*
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* Free the kva allocation for a buffer
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* Must be called only at splbio or higher,
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* as this is the only locking for buffer_map.
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*/
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static void
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bfreekva(struct buf * bp)
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{
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if (bp->b_kvasize) {
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vm_map_delete(buffer_map,
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(vm_offset_t) bp->b_kvabase,
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(vm_offset_t) bp->b_kvabase + bp->b_kvasize
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);
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bp->b_kvasize = 0;
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kvaspacewakeup();
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}
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}
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/*
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* bremfree:
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*
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* Remove the buffer from the appropriate free list.
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*/
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void
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bremfree(struct buf * bp)
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{
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int s = splbio();
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int old_qindex = bp->b_qindex;
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if (bp->b_qindex != QUEUE_NONE) {
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if (bp->b_qindex == QUEUE_EMPTY) {
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kvafreespace -= bp->b_kvasize;
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}
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if (BUF_REFCNT(bp) == 1)
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TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
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else if (BUF_REFCNT(bp) == 0)
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panic("bremfree: not locked");
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else
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/* Temporary panic to verify exclusive locking */
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/* This panic goes away when we allow shared refs */
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panic("bremfree: multiple refs");
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bp->b_qindex = QUEUE_NONE;
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runningbufspace += bp->b_bufsize;
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} else {
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#if !defined(MAX_PERF)
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panic("bremfree: removing a buffer when not on a queue");
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#endif
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}
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/*
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* Fixup numfreebuffers count. If the buffer is invalid or not
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* delayed-write, and it was on the EMPTY, LRU, or AGE queues,
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* the buffer was free and we must decrement numfreebuffers.
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*/
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if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) {
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switch(old_qindex) {
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case QUEUE_EMPTY:
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case QUEUE_LRU:
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case QUEUE_AGE:
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--numfreebuffers;
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break;
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default:
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break;
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}
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}
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splx(s);
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}
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/*
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* Get a buffer with the specified data. Look in the cache first. We
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* must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
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* is set, the buffer is valid and we do not have to do anything ( see
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* getblk() ).
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*/
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int
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bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
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struct buf ** bpp)
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{
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struct buf *bp;
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bp = getblk(vp, blkno, size, 0, 0);
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*bpp = bp;
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/* if not found in cache, do some I/O */
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if ((bp->b_flags & B_CACHE) == 0) {
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if (curproc != NULL)
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curproc->p_stats->p_ru.ru_inblock++;
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KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp));
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bp->b_flags |= B_READ;
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bp->b_flags &= ~(B_ERROR | B_INVAL);
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if (bp->b_rcred == NOCRED) {
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if (cred != NOCRED)
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crhold(cred);
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bp->b_rcred = cred;
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}
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vfs_busy_pages(bp, 0);
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VOP_STRATEGY(vp, bp);
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return (biowait(bp));
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}
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return (0);
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}
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/*
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* Operates like bread, but also starts asynchronous I/O on
|
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* read-ahead blocks. We must clear B_ERROR and B_INVAL prior
|
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* to initiating I/O . If B_CACHE is set, the buffer is valid
|
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* and we do not have to do anything.
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*/
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int
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breadn(struct vnode * vp, daddr_t blkno, int size,
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daddr_t * rablkno, int *rabsize,
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int cnt, struct ucred * cred, struct buf ** bpp)
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{
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struct buf *bp, *rabp;
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int i;
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int rv = 0, readwait = 0;
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*bpp = bp = getblk(vp, blkno, size, 0, 0);
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/* if not found in cache, do some I/O */
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if ((bp->b_flags & B_CACHE) == 0) {
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if (curproc != NULL)
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curproc->p_stats->p_ru.ru_inblock++;
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bp->b_flags |= B_READ;
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bp->b_flags &= ~(B_ERROR | B_INVAL);
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if (bp->b_rcred == NOCRED) {
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if (cred != NOCRED)
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crhold(cred);
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bp->b_rcred = cred;
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}
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vfs_busy_pages(bp, 0);
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VOP_STRATEGY(vp, bp);
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++readwait;
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}
|
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for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
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if (inmem(vp, *rablkno))
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continue;
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rabp = getblk(vp, *rablkno, *rabsize, 0, 0);
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|
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if ((rabp->b_flags & B_CACHE) == 0) {
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if (curproc != NULL)
|
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curproc->p_stats->p_ru.ru_inblock++;
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rabp->b_flags |= B_READ | B_ASYNC;
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rabp->b_flags &= ~(B_ERROR | B_INVAL);
|
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if (rabp->b_rcred == NOCRED) {
|
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if (cred != NOCRED)
|
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crhold(cred);
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rabp->b_rcred = cred;
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}
|
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vfs_busy_pages(rabp, 0);
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BUF_KERNPROC(bp);
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VOP_STRATEGY(vp, rabp);
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} else {
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brelse(rabp);
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}
|
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}
|
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|
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if (readwait) {
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rv = biowait(bp);
|
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}
|
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return (rv);
|
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}
|
|
|
|
/*
|
|
* 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
|
|
bwrite(struct buf * bp)
|
|
{
|
|
int oldflags, s;
|
|
struct vnode *vp;
|
|
struct mount *mp;
|
|
|
|
if (bp->b_flags & B_INVAL) {
|
|
brelse(bp);
|
|
return (0);
|
|
}
|
|
|
|
oldflags = bp->b_flags;
|
|
|
|
#if !defined(MAX_PERF)
|
|
if (BUF_REFCNT(bp) == 0)
|
|
panic("bwrite: buffer is not busy???");
|
|
#endif
|
|
s = splbio();
|
|
bundirty(bp);
|
|
|
|
bp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
|
|
bp->b_flags |= B_WRITEINPROG | B_CACHE;
|
|
|
|
bp->b_vp->v_numoutput++;
|
|
vfs_busy_pages(bp, 1);
|
|
if (curproc != NULL)
|
|
curproc->p_stats->p_ru.ru_oublock++;
|
|
splx(s);
|
|
BUF_KERNPROC(bp);
|
|
VOP_STRATEGY(bp->b_vp, bp);
|
|
|
|
/*
|
|
* Collect statistics on synchronous and asynchronous writes.
|
|
* Writes to block devices are charged to their associated
|
|
* filesystem (if any).
|
|
*/
|
|
if ((vp = bp->b_vp) != NULL) {
|
|
if (vp->v_type == VBLK)
|
|
mp = vp->v_specmountpoint;
|
|
else
|
|
mp = vp->v_mount;
|
|
if (mp != NULL) {
|
|
if ((oldflags & B_ASYNC) == 0)
|
|
mp->mnt_stat.f_syncwrites++;
|
|
else
|
|
mp->mnt_stat.f_asyncwrites++;
|
|
}
|
|
}
|
|
|
|
if ((oldflags & B_ASYNC) == 0) {
|
|
int rtval = biowait(bp);
|
|
brelse(bp);
|
|
return (rtval);
|
|
}
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* 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 vnode *vp;
|
|
|
|
#if !defined(MAX_PERF)
|
|
if (BUF_REFCNT(bp) == 0)
|
|
panic("bdwrite: buffer is not busy");
|
|
#endif
|
|
|
|
if (bp->b_flags & B_INVAL) {
|
|
brelse(bp);
|
|
return;
|
|
}
|
|
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 (bp->b_lblkno == bp->b_blkno) {
|
|
VOP_BMAP(bp->b_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);
|
|
|
|
/*
|
|
* XXX The soft dependency code is not prepared to
|
|
* have I/O done when a bdwrite is requested. For
|
|
* now we just let the write be delayed if it is
|
|
* requested by the soft dependency code.
|
|
*/
|
|
if ((vp = bp->b_vp) &&
|
|
((vp->v_type == VBLK && vp->v_specmountpoint &&
|
|
(vp->v_specmountpoint->mnt_flag & MNT_SOFTDEP)) ||
|
|
(vp->v_mount && (vp->v_mount->mnt_flag & MNT_SOFTDEP))))
|
|
return;
|
|
|
|
if (numdirtybuffers >= hidirtybuffers)
|
|
flushdirtybuffers(0, 0);
|
|
}
|
|
|
|
/*
|
|
* bdirty:
|
|
*
|
|
* Turn buffer into delayed write request. We must clear B_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(bp)
|
|
struct buf *bp;
|
|
{
|
|
KASSERT(bp->b_qindex == QUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
|
|
bp->b_flags &= ~(B_READ|B_RELBUF);
|
|
|
|
if ((bp->b_flags & B_DELWRI) == 0) {
|
|
bp->b_flags |= B_DONE | B_DELWRI;
|
|
reassignbuf(bp, bp->b_vp);
|
|
++numdirtybuffers;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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(bp)
|
|
struct buf *bp;
|
|
{
|
|
KASSERT(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, bp->b_vp);
|
|
--numdirtybuffers;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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) VOP_BWRITE(bp->b_vp, bp);
|
|
}
|
|
|
|
/*
|
|
* bowrite:
|
|
*
|
|
* Ordered write. Start output on a buffer, and flag it so that the
|
|
* device will write it in the order it was queued. The buffer is
|
|
* released when the output completes. bwrite() ( or the VOP routine
|
|
* anyway ) is responsible for handling B_INVAL buffers.
|
|
*/
|
|
int
|
|
bowrite(struct buf * bp)
|
|
{
|
|
bp->b_flags |= B_ORDERED | B_ASYNC;
|
|
return (VOP_BWRITE(bp->b_vp, bp));
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
|
|
|
|
#if 0
|
|
if (bp->b_flags & B_CLUSTER) {
|
|
relpbuf(bp, NULL);
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
s = splbio();
|
|
|
|
if (bp->b_flags & B_LOCKED)
|
|
bp->b_flags &= ~B_ERROR;
|
|
|
|
if ((bp->b_flags & (B_READ | B_ERROR)) == B_ERROR) {
|
|
/*
|
|
* Failed write, redirty. Must clear B_ERROR to prevent
|
|
* pages from being scrapped. Note: B_INVAL is ignored
|
|
* here but will presumably be dealt with later.
|
|
*/
|
|
bp->b_flags &= ~B_ERROR;
|
|
bdirty(bp);
|
|
} else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_FREEBUF)) ||
|
|
(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 && bioops.io_deallocate)
|
|
(*bioops.io_deallocate)(bp);
|
|
if (bp->b_flags & B_DELWRI)
|
|
--numdirtybuffers;
|
|
bp->b_flags &= ~(B_DELWRI | B_CACHE | B_FREEBUF);
|
|
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 (bp->b_flags & B_DELWRI)
|
|
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 B_ERROR or B_NOCACHE is set, pages in the VM object will be
|
|
* invalidated. B_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 ((bp->b_flags & B_VMIO)
|
|
&& !(bp->b_vp->v_tag == VT_NFS &&
|
|
bp->b_vp->v_type != VBLK &&
|
|
(bp->b_flags & B_DELWRI))
|
|
) {
|
|
|
|
int i, j, resid;
|
|
vm_page_t m;
|
|
off_t foff;
|
|
vm_pindex_t poff;
|
|
vm_object_t obj;
|
|
struct vnode *vp;
|
|
|
|
vp = bp->b_vp;
|
|
|
|
/*
|
|
* Get the base offset and length of the buffer. Note that
|
|
* for block sizes that are less then PAGE_SIZE, the b_data
|
|
* base of the buffer does not represent exactly b_offset and
|
|
* neither b_offset nor b_size are necessarily page aligned.
|
|
* Instead, the starting position of b_offset is:
|
|
*
|
|
* b_data + (b_offset & PAGE_MASK)
|
|
*
|
|
* 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;
|
|
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
m = bp->b_pages[i];
|
|
vm_page_flag_clear(m, PG_ZERO);
|
|
if (m == bogus_page) {
|
|
|
|
obj = (vm_object_t) vp->v_object;
|
|
poff = OFF_TO_IDX(bp->b_offset);
|
|
|
|
for (j = i; j < bp->b_npages; j++) {
|
|
m = bp->b_pages[j];
|
|
if (m == bogus_page) {
|
|
m = vm_page_lookup(obj, poff + j);
|
|
#if !defined(MAX_PERF)
|
|
if (!m) {
|
|
panic("brelse: page missing\n");
|
|
}
|
|
#endif
|
|
bp->b_pages[j] = m;
|
|
}
|
|
}
|
|
|
|
if ((bp->b_flags & B_INVAL) == 0) {
|
|
pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_pages, bp->b_npages);
|
|
}
|
|
}
|
|
if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
|
|
int poffset = foff & PAGE_MASK;
|
|
int presid = resid > (PAGE_SIZE - poffset) ?
|
|
(PAGE_SIZE - poffset) : resid;
|
|
|
|
KASSERT(presid >= 0, ("brelse: extra page"));
|
|
vm_page_set_invalid(m, poffset, presid);
|
|
}
|
|
resid -= PAGE_SIZE - (foff & PAGE_MASK);
|
|
foff = (foff + PAGE_SIZE) & ~PAGE_MASK;
|
|
}
|
|
|
|
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 !defined(MAX_PERF)
|
|
if (bp->b_qindex != QUEUE_NONE)
|
|
panic("brelse: free buffer onto another queue???");
|
|
#endif
|
|
if (BUF_REFCNT(bp) > 1) {
|
|
/* Temporary panic to verify exclusive locking */
|
|
/* This panic goes away when we allow shared refs */
|
|
panic("brelse: multiple refs");
|
|
/* do not release to free list */
|
|
BUF_UNLOCK(bp);
|
|
splx(s);
|
|
return;
|
|
}
|
|
|
|
/* enqueue */
|
|
|
|
/* buffers with no memory */
|
|
if (bp->b_bufsize == 0) {
|
|
bp->b_flags |= B_INVAL;
|
|
bp->b_qindex = QUEUE_EMPTY;
|
|
TAILQ_INSERT_HEAD(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
|
|
LIST_REMOVE(bp, b_hash);
|
|
LIST_INSERT_HEAD(&invalhash, bp, b_hash);
|
|
bp->b_dev = NODEV;
|
|
kvafreespace += bp->b_kvasize;
|
|
if (bp->b_kvasize)
|
|
kvaspacewakeup();
|
|
/* buffers with junk contents */
|
|
} else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) {
|
|
bp->b_flags |= B_INVAL;
|
|
bp->b_qindex = QUEUE_AGE;
|
|
TAILQ_INSERT_HEAD(&bufqueues[QUEUE_AGE], bp, b_freelist);
|
|
LIST_REMOVE(bp, b_hash);
|
|
LIST_INSERT_HEAD(&invalhash, bp, b_hash);
|
|
bp->b_dev = NODEV;
|
|
|
|
/* buffers that are locked */
|
|
} else if (bp->b_flags & B_LOCKED) {
|
|
bp->b_qindex = QUEUE_LOCKED;
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist);
|
|
|
|
/* buffers with stale but valid contents */
|
|
} else if (bp->b_flags & B_AGE) {
|
|
bp->b_qindex = QUEUE_AGE;
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_AGE], bp, b_freelist);
|
|
|
|
/* buffers with valid and quite potentially reuseable contents */
|
|
} else {
|
|
bp->b_qindex = QUEUE_LRU;
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
|
|
}
|
|
|
|
/*
|
|
* If B_INVAL, clear B_DELWRI.
|
|
*/
|
|
if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) {
|
|
bp->b_flags &= ~B_DELWRI;
|
|
--numdirtybuffers;
|
|
}
|
|
|
|
runningbufspace -= bp->b_bufsize;
|
|
|
|
/*
|
|
* 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_LOCKED) == 0 && !(bp->b_flags & B_DELWRI))
|
|
bufcountwakeup();
|
|
|
|
/*
|
|
* Something we can maybe free.
|
|
*/
|
|
|
|
if (bp->b_bufsize)
|
|
bufspacewakeup();
|
|
|
|
/* unlock */
|
|
BUF_UNLOCK(bp);
|
|
bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* Release a buffer back to the appropriate queue but do not try to free
|
|
* it.
|
|
*
|
|
* 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.
|
|
*/
|
|
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 !defined(MAX_PERF)
|
|
if (bp->b_qindex != QUEUE_NONE)
|
|
panic("bqrelse: free buffer onto another queue???");
|
|
#endif
|
|
if (BUF_REFCNT(bp) > 1) {
|
|
/* do not release to free list */
|
|
panic("bqrelse: multiple refs");
|
|
BUF_UNLOCK(bp);
|
|
splx(s);
|
|
return;
|
|
}
|
|
if (bp->b_flags & B_LOCKED) {
|
|
bp->b_flags &= ~B_ERROR;
|
|
bp->b_qindex = QUEUE_LOCKED;
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LOCKED], bp, b_freelist);
|
|
/* buffers with stale but valid contents */
|
|
} else {
|
|
bp->b_qindex = QUEUE_LRU;
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
|
|
}
|
|
|
|
runningbufspace -= bp->b_bufsize;
|
|
|
|
if ((bp->b_flags & B_LOCKED) == 0 &&
|
|
((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
|
|
) {
|
|
bufcountwakeup();
|
|
}
|
|
|
|
/*
|
|
* Something we can maybe wakeup
|
|
*/
|
|
if (bp->b_bufsize)
|
|
bufspacewakeup();
|
|
|
|
/* unlock */
|
|
BUF_UNLOCK(bp);
|
|
bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
|
|
splx(s);
|
|
}
|
|
|
|
static void
|
|
vfs_vmio_release(bp)
|
|
struct buf *bp;
|
|
{
|
|
int i, s;
|
|
vm_page_t m;
|
|
|
|
s = splvm();
|
|
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) {
|
|
vm_page_flag_clear(m, PG_ZERO);
|
|
/*
|
|
* Might as well free the page if we can and it has
|
|
* no valid data.
|
|
*/
|
|
if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) {
|
|
vm_page_busy(m);
|
|
vm_page_protect(m, VM_PROT_NONE);
|
|
vm_page_free(m);
|
|
}
|
|
}
|
|
}
|
|
bufspace -= bp->b_bufsize;
|
|
vmiospace -= bp->b_bufsize;
|
|
runningbufspace -= bp->b_bufsize;
|
|
splx(s);
|
|
pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
|
|
if (bp->b_bufsize)
|
|
bufspacewakeup();
|
|
bp->b_npages = 0;
|
|
bp->b_bufsize = 0;
|
|
bp->b_flags &= ~B_VMIO;
|
|
if (bp->b_vp)
|
|
brelvp(bp);
|
|
}
|
|
|
|
/*
|
|
* Check to see if a block is currently memory resident.
|
|
*/
|
|
struct buf *
|
|
gbincore(struct vnode * vp, daddr_t blkno)
|
|
{
|
|
struct buf *bp;
|
|
struct bufhashhdr *bh;
|
|
|
|
bh = BUFHASH(vp, blkno);
|
|
bp = bh->lh_first;
|
|
|
|
/* Search hash chain */
|
|
while (bp != NULL) {
|
|
/* hit */
|
|
if (bp->b_vp == vp && bp->b_lblkno == blkno &&
|
|
(bp->b_flags & B_INVAL) == 0) {
|
|
break;
|
|
}
|
|
bp = bp->b_hash.le_next;
|
|
}
|
|
return (bp);
|
|
}
|
|
|
|
/*
|
|
* this routine implements clustered async writes for
|
|
* clearing out B_DELWRI buffers... This is much better
|
|
* than the old way of writing only one buffer at a time.
|
|
*/
|
|
int
|
|
vfs_bio_awrite(struct buf * bp)
|
|
{
|
|
int i;
|
|
daddr_t lblkno = bp->b_lblkno;
|
|
struct vnode *vp = bp->b_vp;
|
|
int s;
|
|
int ncl;
|
|
struct buf *bpa;
|
|
int nwritten;
|
|
int size;
|
|
int maxcl;
|
|
|
|
s = splbio();
|
|
/*
|
|
* right now we support clustered writing only to regular files, and
|
|
* then only if our I/O system is not saturated.
|
|
*/
|
|
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;
|
|
|
|
for (i = 1; i < maxcl; i++) {
|
|
if ((bpa = gbincore(vp, lblkno + i)) &&
|
|
BUF_REFCNT(bpa) == 0 &&
|
|
((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) ==
|
|
(B_DELWRI | B_CLUSTEROK)) &&
|
|
(bpa->b_bufsize == size)) {
|
|
if ((bpa->b_blkno == bpa->b_lblkno) ||
|
|
(bpa->b_blkno != bp->b_blkno + ((i * size) >> DEV_BSHIFT)))
|
|
break;
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
ncl = i;
|
|
/*
|
|
* this is a possible cluster write
|
|
*/
|
|
if (ncl != 1) {
|
|
nwritten = cluster_wbuild(vp, size, lblkno, ncl);
|
|
splx(s);
|
|
return nwritten;
|
|
}
|
|
}
|
|
|
|
BUF_LOCK(bp, LK_EXCLUSIVE);
|
|
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) VOP_BWRITE(bp->b_vp, 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 )
|
|
*
|
|
* We do *not* attempt to flush dirty buffers more then one level deep.
|
|
* I.e., if P_FLSINPROG is set we do not flush dirty buffers at all.
|
|
*
|
|
* If P_FLSINPROG is set, we are allowed to dip into our emergency
|
|
* reserve.
|
|
*/
|
|
static struct buf *
|
|
getnewbuf(struct vnode *vp, daddr_t blkno,
|
|
int slpflag, int slptimeo, int size, int maxsize)
|
|
{
|
|
struct buf *bp;
|
|
struct buf *nbp;
|
|
struct buf *dbp;
|
|
int outofspace;
|
|
int nqindex;
|
|
int defrag = 0;
|
|
static int newbufcnt = 0;
|
|
int lastnewbuf = newbufcnt;
|
|
|
|
restart:
|
|
/*
|
|
* Calculate whether we are out of buffer space. This state is
|
|
* recalculated on every restart. If we are out of space, we
|
|
* have to turn off defragmentation. The outofspace code will
|
|
* defragment too, but the looping conditionals will be messed up
|
|
* if both outofspace and defrag are on.
|
|
*/
|
|
|
|
dbp = NULL;
|
|
outofspace = 0;
|
|
if (bufspace >= hibufspace) {
|
|
if ((curproc->p_flag & P_FLSINPROG) == 0 ||
|
|
bufspace >= maxbufspace
|
|
) {
|
|
outofspace = 1;
|
|
defrag = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* defrag state is semi-persistant. 1 means we are flagged for
|
|
* defragging. -1 means we actually defragged something.
|
|
*/
|
|
/* nop */
|
|
|
|
/*
|
|
* Setup for scan. If we do not have enough free buffers,
|
|
* we setup a degenerate case that falls through the while.
|
|
*
|
|
* If we are in the middle of a flush, we can dip into the
|
|
* emergency reserve.
|
|
*
|
|
* If we are out of space, we skip trying to scan QUEUE_EMPTY
|
|
* because those buffers are, well, empty.
|
|
*/
|
|
|
|
if ((curproc->p_flag & P_FLSINPROG) == 0 &&
|
|
numfreebuffers < lofreebuffers) {
|
|
nqindex = QUEUE_LRU;
|
|
nbp = NULL;
|
|
} else {
|
|
nqindex = QUEUE_EMPTY;
|
|
if (outofspace ||
|
|
(nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY])) == NULL) {
|
|
nqindex = QUEUE_AGE;
|
|
nbp = TAILQ_FIRST(&bufqueues[QUEUE_AGE]);
|
|
if (nbp == NULL) {
|
|
nqindex = QUEUE_LRU;
|
|
nbp = TAILQ_FIRST(&bufqueues[QUEUE_LRU]);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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_AGE;
|
|
if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_AGE])))
|
|
break;
|
|
/* fall through */
|
|
case QUEUE_AGE:
|
|
nqindex = QUEUE_LRU;
|
|
if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_LRU])))
|
|
break;
|
|
/* fall through */
|
|
case QUEUE_LRU:
|
|
/*
|
|
* nbp is NULL.
|
|
*/
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Sanity Checks
|
|
*/
|
|
KASSERT(BUF_REFCNT(bp) == 0, ("getnewbuf: busy buffer %p on free list", bp));
|
|
KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
|
|
|
|
/*
|
|
* Here we try to move NON VMIO buffers to the end of the
|
|
* LRU queue in order to make VMIO buffers more readily
|
|
* freeable. We also try to move buffers with a positive
|
|
* usecount to the end.
|
|
*
|
|
* Note that by moving the bp to the end, we setup a following
|
|
* loop. Since we continue to decrement b_usecount this
|
|
* is ok and, in fact, desireable.
|
|
*
|
|
* If we are at the end of the list, we move ourself to the
|
|
* same place and need to fixup nbp and nqindex to handle
|
|
* the following case.
|
|
*/
|
|
|
|
if ((qindex == QUEUE_LRU) && bp->b_usecount > 0) {
|
|
if ((bp->b_flags & B_VMIO) == 0 ||
|
|
(vmiospace < maxvmiobufspace)
|
|
) {
|
|
--bp->b_usecount;
|
|
TAILQ_REMOVE(&bufqueues[QUEUE_LRU], bp, b_freelist);
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
|
|
if (nbp == NULL) {
|
|
nqindex = qindex;
|
|
nbp = bp;
|
|
}
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we come across a delayed write and numdirtybuffers should
|
|
* be flushed, try to write it out. Only if P_FLSINPROG is
|
|
* not set. We can't afford to recursively stack more then
|
|
* one deep due to the possibility of having deep VFS call
|
|
* stacks.
|
|
*
|
|
* Limit the number of dirty buffers we are willing to try
|
|
* to recover since it really isn't our job here.
|
|
*/
|
|
if ((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) {
|
|
/*
|
|
* This is rather complex, but necessary. If we come
|
|
* across a B_DELWRI buffer we have to flush it in
|
|
* order to use it. We only do this if we absolutely
|
|
* need to. We must also protect against too much
|
|
* recursion which might run us out of stack due to
|
|
* deep VFS call stacks.
|
|
*
|
|
* In heavy-writing situations, QUEUE_LRU can contain
|
|
* a large number of DELWRI buffers at its head. These
|
|
* buffers must be moved to the tail if they cannot be
|
|
* written async in order to reduce the scanning time
|
|
* required to skip past these buffers in later
|
|
* getnewbuf() calls.
|
|
*/
|
|
if ((curproc->p_flag & P_FLSINPROG) ||
|
|
numdirtybuffers < hidirtybuffers) {
|
|
if (qindex == QUEUE_LRU) {
|
|
/*
|
|
* dbp prevents us from looping forever
|
|
* if all bps in QUEUE_LRU are dirty.
|
|
*/
|
|
if (bp == dbp) {
|
|
bp = NULL;
|
|
break;
|
|
}
|
|
if (dbp == NULL)
|
|
dbp = TAILQ_LAST(&bufqueues[QUEUE_LRU], bqueues);
|
|
TAILQ_REMOVE(&bufqueues[QUEUE_LRU], bp, b_freelist);
|
|
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_LRU], bp, b_freelist);
|
|
}
|
|
continue;
|
|
}
|
|
curproc->p_flag |= P_FLSINPROG;
|
|
vfs_bio_awrite(bp);
|
|
curproc->p_flag &= ~P_FLSINPROG;
|
|
goto restart;
|
|
}
|
|
|
|
if (defrag > 0 && bp->b_kvasize == 0)
|
|
continue;
|
|
if (outofspace > 0 && bp->b_bufsize == 0)
|
|
continue;
|
|
|
|
/*
|
|
* Start freeing the bp. This is somewhat involved. nbp
|
|
* remains valid only for QUEUE_EMPTY bp's.
|
|
*/
|
|
|
|
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0)
|
|
panic("getnewbuf: locked buf");
|
|
bremfree(bp);
|
|
|
|
if (qindex == QUEUE_LRU || qindex == QUEUE_AGE) {
|
|
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 && bioops.io_deallocate)
|
|
(*bioops.io_deallocate)(bp);
|
|
|
|
LIST_REMOVE(bp, b_hash);
|
|
LIST_INSERT_HEAD(&invalhash, bp, b_hash);
|
|
|
|
if (bp->b_bufsize)
|
|
allocbuf(bp, 0);
|
|
|
|
bp->b_flags = 0;
|
|
bp->b_dev = NODEV;
|
|
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_usecount = 5;
|
|
|
|
LIST_INIT(&bp->b_dep);
|
|
|
|
/*
|
|
* Ok, now that we have a free buffer, if we are defragging
|
|
* we have to recover the kvaspace.
|
|
*/
|
|
|
|
if (defrag > 0) {
|
|
defrag = -1;
|
|
bp->b_flags |= B_INVAL;
|
|
bfreekva(bp);
|
|
brelse(bp);
|
|
goto restart;
|
|
}
|
|
|
|
if (outofspace > 0) {
|
|
outofspace = -1;
|
|
bp->b_flags |= B_INVAL;
|
|
bfreekva(bp);
|
|
brelse(bp);
|
|
goto restart;
|
|
}
|
|
|
|
/*
|
|
* We are done
|
|
*/
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If we exhausted our list, sleep as appropriate.
|
|
*/
|
|
|
|
if (bp == NULL) {
|
|
int flags;
|
|
|
|
dosleep:
|
|
if (defrag > 0)
|
|
flags = VFS_BIO_NEED_KVASPACE;
|
|
else if (outofspace > 0)
|
|
flags = VFS_BIO_NEED_BUFSPACE;
|
|
else
|
|
flags = VFS_BIO_NEED_ANY;
|
|
|
|
(void) speedup_syncer();
|
|
needsbuffer |= flags;
|
|
while (needsbuffer & flags) {
|
|
if (tsleep(&needsbuffer, (PRIBIO + 4) | slpflag,
|
|
"newbuf", slptimeo))
|
|
return (NULL);
|
|
}
|
|
} else {
|
|
/*
|
|
* We finally have a valid bp. We aren't quite out of the
|
|
* woods, we still have to reserve kva space.
|
|
*/
|
|
vm_offset_t addr = 0;
|
|
|
|
maxsize = (maxsize + PAGE_MASK) & ~PAGE_MASK;
|
|
|
|
if (maxsize != bp->b_kvasize) {
|
|
bfreekva(bp);
|
|
|
|
if (vm_map_findspace(buffer_map,
|
|
vm_map_min(buffer_map), maxsize, &addr)
|
|
) {
|
|
/*
|
|
* Uh oh. Buffer map is to fragmented. Try
|
|
* to defragment.
|
|
*/
|
|
if (defrag <= 0) {
|
|
defrag = 1;
|
|
bp->b_flags |= B_INVAL;
|
|
brelse(bp);
|
|
goto restart;
|
|
}
|
|
/*
|
|
* Uh oh. We couldn't seem to defragment
|
|
*/
|
|
bp = NULL;
|
|
goto dosleep;
|
|
}
|
|
}
|
|
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;
|
|
}
|
|
bp->b_data = bp->b_kvabase;
|
|
}
|
|
|
|
/*
|
|
* If we have slept at some point in this process and another
|
|
* process has managed to allocate a new buffer while we slept,
|
|
* we have to return NULL so that our caller can recheck to
|
|
* ensure that the other process did not create an identically
|
|
* identified buffer to the one we were requesting. We make this
|
|
* check by incrementing the static int newbufcnt each time we
|
|
* successfully allocate a new buffer. By saving the value of
|
|
* newbufcnt in our local lastnewbuf, we can compare newbufcnt
|
|
* with lastnewbuf to see if any other process managed to
|
|
* allocate a buffer while we were doing so ourselves.
|
|
*
|
|
* Note that bp, if valid, is locked.
|
|
*/
|
|
if (lastnewbuf == newbufcnt) {
|
|
/*
|
|
* No buffers allocated, so we can return one if we were
|
|
* successful, or continue trying if we were not successful.
|
|
*/
|
|
if (bp != NULL) {
|
|
newbufcnt += 1;
|
|
return (bp);
|
|
}
|
|
goto restart;
|
|
}
|
|
/*
|
|
* Another process allocated a buffer since we were called, so
|
|
* we have to free the one we allocated and return NULL to let
|
|
* our caller recheck to see if a new buffer is still needed.
|
|
*/
|
|
if (bp != NULL) {
|
|
bp->b_flags |= B_INVAL;
|
|
brelse(bp);
|
|
}
|
|
return (NULL);
|
|
}
|
|
|
|
/*
|
|
* waitfreebuffers:
|
|
*
|
|
* Wait for sufficient free buffers. This routine is not called if
|
|
* curproc is the update process so we do not have to do anything
|
|
* fancy.
|
|
*/
|
|
|
|
static void
|
|
waitfreebuffers(int slpflag, int slptimeo)
|
|
{
|
|
while (numfreebuffers < hifreebuffers) {
|
|
flushdirtybuffers(slpflag, slptimeo);
|
|
if (numfreebuffers >= hifreebuffers)
|
|
break;
|
|
needsbuffer |= VFS_BIO_NEED_FREE;
|
|
if (tsleep(&needsbuffer, (PRIBIO + 4)|slpflag, "biofre", slptimeo))
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* flushdirtybuffers:
|
|
*
|
|
* This routine is called when we get too many dirty buffers.
|
|
*
|
|
* We have to protect ourselves from recursion, but we also do not want
|
|
* other process's flushdirtybuffers() to interfere with the syncer if
|
|
* it decides to flushdirtybuffers().
|
|
*
|
|
* In order to maximize operations, we allow any process to flush
|
|
* dirty buffers and use P_FLSINPROG to prevent recursion.
|
|
*/
|
|
|
|
static void
|
|
flushdirtybuffers(int slpflag, int slptimeo)
|
|
{
|
|
int s;
|
|
|
|
s = splbio();
|
|
|
|
if (curproc->p_flag & P_FLSINPROG) {
|
|
splx(s);
|
|
return;
|
|
}
|
|
curproc->p_flag |= P_FLSINPROG;
|
|
|
|
while (numdirtybuffers > lodirtybuffers) {
|
|
if (flushbufqueues() == 0)
|
|
break;
|
|
}
|
|
|
|
curproc->p_flag &= ~P_FLSINPROG;
|
|
|
|
splx(s);
|
|
}
|
|
|
|
static int
|
|
flushbufqueues(void)
|
|
{
|
|
struct buf *bp;
|
|
int qindex;
|
|
int r = 0;
|
|
|
|
qindex = QUEUE_AGE;
|
|
bp = TAILQ_FIRST(&bufqueues[QUEUE_AGE]);
|
|
|
|
for (;;) {
|
|
if (bp == NULL) {
|
|
if (qindex == QUEUE_LRU)
|
|
break;
|
|
qindex = QUEUE_LRU;
|
|
if ((bp = TAILQ_FIRST(&bufqueues[QUEUE_LRU])) == NULL)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Try to free up B_INVAL delayed-write buffers rather then
|
|
* writing them out. Note also that NFS is somewhat sensitive
|
|
* to B_INVAL buffers so it is doubly important that we do
|
|
* this.
|
|
*/
|
|
if ((bp->b_flags & B_DELWRI) != 0) {
|
|
if (bp->b_flags & B_INVAL) {
|
|
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0)
|
|
panic("flushbufqueues: locked buf");
|
|
bremfree(bp);
|
|
brelse(bp);
|
|
} else {
|
|
vfs_bio_awrite(bp);
|
|
}
|
|
++r;
|
|
break;
|
|
}
|
|
bp = TAILQ_NEXT(bp, b_freelist);
|
|
}
|
|
return(r);
|
|
}
|
|
|
|
/*
|
|
* Check to see if a block is currently memory resident.
|
|
*/
|
|
struct buf *
|
|
incore(struct vnode * vp, daddr_t blkno)
|
|
{
|
|
struct buf *bp;
|
|
|
|
int s = splbio();
|
|
bp = gbincore(vp, blkno);
|
|
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.
|
|
*/
|
|
|
|
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;
|
|
|
|
if (incore(vp, blkno))
|
|
return 1;
|
|
if (vp->v_mount == NULL)
|
|
return 0;
|
|
if ((vp->v_object == NULL) || (vp->v_flag & VOBJBUF) == 0)
|
|
return 0;
|
|
|
|
obj = vp->v_object;
|
|
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;
|
|
|
|
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)
|
|
return 0;
|
|
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)
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
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;
|
|
|
|
/*
|
|
* 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_flag_clear(bp->b_pages[i], PG_ZERO);
|
|
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);
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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 VOP_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 B_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)
|
|
{
|
|
struct buf *bp;
|
|
int s;
|
|
struct bufhashhdr *bh;
|
|
|
|
#if !defined(MAX_PERF)
|
|
if (size > MAXBSIZE)
|
|
panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
|
|
#endif
|
|
|
|
s = splbio();
|
|
loop:
|
|
/*
|
|
* Block if we are low on buffers. The syncer is allowed more
|
|
* buffers in order to avoid a deadlock.
|
|
*/
|
|
if (curproc == updateproc && numfreebuffers == 0) {
|
|
needsbuffer |= VFS_BIO_NEED_ANY;
|
|
tsleep(&needsbuffer, (PRIBIO + 4) | slpflag, "newbuf",
|
|
slptimeo);
|
|
} else if (curproc != updateproc && numfreebuffers < lofreebuffers) {
|
|
waitfreebuffers(slpflag, slptimeo);
|
|
}
|
|
|
|
if ((bp = gbincore(vp, blkno))) {
|
|
/*
|
|
* Buffer is in-core
|
|
*/
|
|
|
|
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) {
|
|
if (bp->b_usecount < BUF_MAXUSE)
|
|
++bp->b_usecount;
|
|
if (BUF_TIMELOCK(bp, LK_EXCLUSIVE | LK_SLEEPFAIL,
|
|
"getblk", slpflag, slptimeo) == ENOLCK)
|
|
goto loop;
|
|
splx(s);
|
|
return (struct buf *) NULL;
|
|
}
|
|
|
|
/*
|
|
* The buffer is locked. B_CACHE is cleared if the buffer is
|
|
* invalid. Ohterwise, 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;
|
|
VOP_BWRITE(bp->b_vp, 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;
|
|
VOP_BWRITE(bp->b_vp, 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.
|
|
*/
|
|
|
|
if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
|
|
VOP_BWRITE(bp->b_vp, bp);
|
|
goto loop;
|
|
}
|
|
|
|
if (bp->b_usecount < BUF_MAXUSE)
|
|
++bp->b_usecount;
|
|
splx(s);
|
|
bp->b_flags &= ~B_DONE;
|
|
} else {
|
|
/*
|
|
* 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).
|
|
*/
|
|
int bsize, maxsize, vmio;
|
|
off_t offset;
|
|
|
|
if (vp->v_type == VBLK)
|
|
bsize = DEV_BSIZE;
|
|
else if (vp->v_mountedhere)
|
|
bsize = vp->v_mountedhere->mnt_stat.f_iosize;
|
|
else if (vp->v_mount)
|
|
bsize = vp->v_mount->mnt_stat.f_iosize;
|
|
else
|
|
bsize = size;
|
|
|
|
offset = (off_t)blkno * bsize;
|
|
vmio = (vp->v_object != 0) && (vp->v_flag & VOBJBUF);
|
|
maxsize = vmio ? size + (offset & PAGE_MASK) : size;
|
|
maxsize = imax(maxsize, bsize);
|
|
|
|
if ((bp = getnewbuf(vp, blkno,
|
|
slpflag, slptimeo, size, maxsize)) == 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.
|
|
*/
|
|
if (gbincore(vp, blkno)) {
|
|
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);
|
|
LIST_REMOVE(bp, b_hash);
|
|
bh = BUFHASH(vp, blkno);
|
|
LIST_INSERT_HEAD(bh, bp, b_hash);
|
|
|
|
/*
|
|
* 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 (vp->v_type != VREG && vp->v_type != VBLK)
|
|
printf("getblk: vmioing file type %d???\n", vp->v_type);
|
|
#endif
|
|
} else {
|
|
bp->b_flags &= ~B_VMIO;
|
|
}
|
|
|
|
allocbuf(bp, size);
|
|
|
|
splx(s);
|
|
bp->b_flags &= ~B_DONE;
|
|
}
|
|
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;
|
|
|
|
s = splbio();
|
|
while ((bp = getnewbuf(0, (daddr_t) 0, 0, 0, size, MAXBSIZE)) == 0);
|
|
splx(s);
|
|
allocbuf(bp, size);
|
|
bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
|
|
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;
|
|
|
|
#if !defined(MAX_PERF)
|
|
if (BUF_REFCNT(bp) == 0)
|
|
panic("allocbuf: buffer not busy");
|
|
|
|
if (bp->b_kvasize < size)
|
|
panic("allocbuf: buffer too small");
|
|
#endif
|
|
|
|
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 !defined(NO_B_MALLOC)
|
|
if (bp->b_flags & B_MALLOC)
|
|
newbsize = mbsize;
|
|
else
|
|
#endif
|
|
newbsize = round_page(size);
|
|
|
|
if (newbsize < bp->b_bufsize) {
|
|
#if !defined(NO_B_MALLOC)
|
|
/*
|
|
* malloced buffers are not shrunk
|
|
*/
|
|
if (bp->b_flags & B_MALLOC) {
|
|
if (newbsize) {
|
|
bp->b_bcount = size;
|
|
} else {
|
|
free(bp->b_data, M_BIOBUF);
|
|
bufspace -= bp->b_bufsize;
|
|
bufmallocspace -= bp->b_bufsize;
|
|
runningbufspace -= bp->b_bufsize;
|
|
if (bp->b_bufsize)
|
|
bufspacewakeup();
|
|
bp->b_data = bp->b_kvabase;
|
|
bp->b_bufsize = 0;
|
|
bp->b_bcount = 0;
|
|
bp->b_flags &= ~B_MALLOC;
|
|
}
|
|
return 1;
|
|
}
|
|
#endif
|
|
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) {
|
|
#if !defined(NO_B_MALLOC)
|
|
/*
|
|
* We only use malloced memory on the first allocation.
|
|
* and revert to page-allocated memory when the buffer grows.
|
|
*/
|
|
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;
|
|
bufspace += mbsize;
|
|
bufmallocspace += mbsize;
|
|
runningbufspace += bp->b_bufsize;
|
|
return 1;
|
|
}
|
|
#endif
|
|
origbuf = NULL;
|
|
origbufsize = 0;
|
|
#if !defined(NO_B_MALLOC)
|
|
/*
|
|
* 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;
|
|
bufspace -= bp->b_bufsize;
|
|
bufmallocspace -= bp->b_bufsize;
|
|
runningbufspace -= bp->b_bufsize;
|
|
if (bp->b_bufsize)
|
|
bufspacewakeup();
|
|
bp->b_bufsize = 0;
|
|
bp->b_flags &= ~B_MALLOC;
|
|
newbsize = round_page(newbsize);
|
|
}
|
|
#endif
|
|
vm_hold_load_pages(
|
|
bp,
|
|
(vm_offset_t) bp->b_data + bp->b_bufsize,
|
|
(vm_offset_t) bp->b_data + newbsize);
|
|
#if !defined(NO_B_MALLOC)
|
|
if (origbuf) {
|
|
bcopy(origbuf, bp->b_data, origbufsize);
|
|
free(origbuf, M_BIOBUF);
|
|
}
|
|
#endif
|
|
}
|
|
} else {
|
|
vm_page_t m;
|
|
int desiredpages;
|
|
|
|
newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
|
|
desiredpages = (size == 0) ? 0 :
|
|
num_pages((bp->b_offset & PAGE_MASK) + newbsize);
|
|
|
|
#if !defined(NO_B_MALLOC)
|
|
if (bp->b_flags & B_MALLOC)
|
|
panic("allocbuf: VMIO buffer can't be malloced");
|
|
#endif
|
|
/*
|
|
* 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) {
|
|
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_busy(m, TRUE, "biodep"))
|
|
;
|
|
|
|
bp->b_pages[i] = NULL;
|
|
vm_page_unwire(m, 0);
|
|
}
|
|
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 = vp->v_object;
|
|
|
|
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) {
|
|
m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL);
|
|
if (m == NULL) {
|
|
VM_WAIT;
|
|
vm_pageout_deficit += desiredpages - bp->b_npages;
|
|
} else {
|
|
vm_page_wire(m);
|
|
vm_page_wakeup(m);
|
|
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
|
|
*
|
|
*/
|
|
|
|
if (vm_page_sleep_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_flag_clear(m, PG_ZERO);
|
|
vm_page_wire(m);
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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 (bp->b_flags & B_VMIO)
|
|
vmiospace += (newbsize - bp->b_bufsize);
|
|
bufspace += (newbsize - bp->b_bufsize);
|
|
runningbufspace += (newbsize - bp->b_bufsize);
|
|
if (newbsize < bp->b_bufsize)
|
|
bufspacewakeup();
|
|
bp->b_bufsize = newbsize; /* actual buffer allocation */
|
|
bp->b_bcount = size; /* requested buffer size */
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* biowait:
|
|
*
|
|
* Wait for buffer I/O completion, returning error status. The buffer
|
|
* is left locked and B_DONE on return. B_EINTR is converted into a EINTR
|
|
* error and cleared.
|
|
*/
|
|
int
|
|
biowait(register struct buf * bp)
|
|
{
|
|
int s;
|
|
|
|
s = splbio();
|
|
while ((bp->b_flags & B_DONE) == 0)
|
|
#if defined(NO_SCHEDULE_MODS)
|
|
tsleep(bp, PRIBIO, "biowait", 0);
|
|
#else
|
|
if (bp->b_flags & B_READ)
|
|
tsleep(bp, PRIBIO, "biord", 0);
|
|
else
|
|
tsleep(bp, PRIBIO, "biowr", 0);
|
|
#endif
|
|
splx(s);
|
|
if (bp->b_flags & B_EINTR) {
|
|
bp->b_flags &= ~B_EINTR;
|
|
return (EINTR);
|
|
}
|
|
if (bp->b_flags & B_ERROR) {
|
|
return (bp->b_error ? bp->b_error : EIO);
|
|
} else {
|
|
return (0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* biodone:
|
|
*
|
|
* 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
|
|
biodone(register struct buf * bp)
|
|
{
|
|
int s;
|
|
|
|
s = splbio();
|
|
|
|
KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy", bp));
|
|
KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
|
|
|
|
bp->b_flags |= B_DONE;
|
|
|
|
if (bp->b_flags & B_FREEBUF) {
|
|
brelse(bp);
|
|
splx(s);
|
|
return;
|
|
}
|
|
|
|
if ((bp->b_flags & B_READ) == 0) {
|
|
vwakeup(bp);
|
|
}
|
|
|
|
/* call optional completion function if requested */
|
|
if (bp->b_flags & B_CALL) {
|
|
bp->b_flags &= ~B_CALL;
|
|
(*bp->b_iodone) (bp);
|
|
splx(s);
|
|
return;
|
|
}
|
|
if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete)
|
|
(*bioops.io_complete)(bp);
|
|
|
|
if (bp->b_flags & B_VMIO) {
|
|
int i, resid;
|
|
vm_ooffset_t foff;
|
|
vm_page_t m;
|
|
vm_object_t obj;
|
|
int iosize;
|
|
struct vnode *vp = bp->b_vp;
|
|
|
|
obj = vp->v_object;
|
|
|
|
#if defined(VFS_BIO_DEBUG)
|
|
if (vp->v_usecount == 0) {
|
|
panic("biodone: zero vnode ref count");
|
|
}
|
|
|
|
if (vp->v_object == NULL) {
|
|
panic("biodone: missing VM object");
|
|
}
|
|
|
|
if ((vp->v_flag & VOBJBUF) == 0) {
|
|
panic("biodone: vnode is not setup for merged cache");
|
|
}
|
|
#endif
|
|
|
|
foff = bp->b_offset;
|
|
KASSERT(bp->b_offset != NOOFFSET,
|
|
("biodone: no buffer offset"));
|
|
|
|
#if !defined(MAX_PERF)
|
|
if (!obj) {
|
|
panic("biodone: no object");
|
|
}
|
|
#endif
|
|
#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;
|
|
if ((bp->b_flags & (B_READ|B_FREEBUF|B_INVAL|B_NOCACHE|B_ERROR)) == B_READ) {
|
|
bp->b_flags |= B_CACHE;
|
|
}
|
|
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
int bogusflag = 0;
|
|
m = bp->b_pages[i];
|
|
if (m == bogus_page) {
|
|
bogusflag = 1;
|
|
m = vm_page_lookup(obj, OFF_TO_IDX(foff));
|
|
if (!m) {
|
|
#if defined(VFS_BIO_DEBUG)
|
|
printf("biodone: page disappeared\n");
|
|
#endif
|
|
vm_object_pip_subtract(obj, 1);
|
|
bp->b_flags &= ~B_CACHE;
|
|
continue;
|
|
}
|
|
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(%lu)/m->pindex(%d) mismatch\n",
|
|
(unsigned long)foff, m->pindex);
|
|
}
|
|
#endif
|
|
resid = IDX_TO_OFF(m->pindex + 1) - foff;
|
|
if (resid > iosize)
|
|
resid = iosize;
|
|
|
|
/*
|
|
* 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_flags & B_READ) && !bogusflag && resid > 0) {
|
|
vfs_page_set_valid(bp, foff, i, m);
|
|
}
|
|
vm_page_flag_clear(m, PG_ZERO);
|
|
|
|
/*
|
|
* 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) {
|
|
#if !defined(MAX_PERF)
|
|
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);
|
|
#endif
|
|
if (vp->v_type != VBLK)
|
|
#if !defined(MAX_PERF)
|
|
printf(" iosize: %ld, lblkno: %d, flags: 0x%lx, npages: %d\n",
|
|
bp->b_vp->v_mount->mnt_stat.f_iosize,
|
|
(int) bp->b_lblkno,
|
|
bp->b_flags, bp->b_npages);
|
|
else
|
|
printf(" VDEV, lblkno: %d, flags: 0x%lx, npages: %d\n",
|
|
(int) bp->b_lblkno,
|
|
bp->b_flags, bp->b_npages);
|
|
printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n",
|
|
m->valid, m->dirty, m->wire_count);
|
|
#endif
|
|
panic("biodone: page busy < 0\n");
|
|
}
|
|
vm_page_io_finish(m);
|
|
vm_object_pip_subtract(obj, 1);
|
|
foff += resid;
|
|
iosize -= resid;
|
|
}
|
|
if (obj)
|
|
vm_object_pip_wakeupn(obj, 0);
|
|
}
|
|
/*
|
|
* 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_ERROR | B_RELBUF)) != 0)
|
|
brelse(bp);
|
|
else
|
|
bqrelse(bp);
|
|
} else {
|
|
wakeup(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;
|
|
|
|
if (bp->b_flags & B_VMIO) {
|
|
struct vnode *vp = bp->b_vp;
|
|
vm_object_t obj = vp->v_object;
|
|
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
vm_page_t m = bp->b_pages[i];
|
|
|
|
if (m == bogus_page) {
|
|
m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
|
|
#if !defined(MAX_PERF)
|
|
if (!m) {
|
|
panic("vfs_unbusy_pages: page missing\n");
|
|
}
|
|
#endif
|
|
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_flag_clear(m, PG_ZERO);
|
|
vm_page_io_finish(m);
|
|
}
|
|
vm_object_pip_wakeupn(obj, 0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/*
|
|
* 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) & ~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 B_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;
|
|
|
|
if (bp->b_flags & B_VMIO) {
|
|
struct vnode *vp = bp->b_vp;
|
|
vm_object_t obj = vp->v_object;
|
|
vm_ooffset_t foff;
|
|
|
|
foff = bp->b_offset;
|
|
KASSERT(bp->b_offset != NOOFFSET,
|
|
("vfs_busy_pages: no buffer offset"));
|
|
vfs_setdirty(bp);
|
|
|
|
retry:
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
vm_page_t m = bp->b_pages[i];
|
|
if (vm_page_sleep_busy(m, FALSE, "vbpage"))
|
|
goto retry;
|
|
}
|
|
|
|
bogus = 0;
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
vm_page_t m = bp->b_pages[i];
|
|
|
|
vm_page_flag_clear(m, PG_ZERO);
|
|
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.
|
|
*/
|
|
|
|
vm_page_protect(m, VM_PROT_NONE);
|
|
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) & ~PAGE_MASK;
|
|
}
|
|
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;
|
|
|
|
if (bp->b_flags & B_VMIO) {
|
|
vm_ooffset_t foff;
|
|
|
|
foff = bp->b_offset;
|
|
KASSERT(bp->b_offset != NOOFFSET,
|
|
("vfs_clean_pages: no buffer offset"));
|
|
for (i = 0; i < bp->b_npages; i++) {
|
|
vm_page_t m = bp->b_pages[i];
|
|
vm_ooffset_t noff = (foff + PAGE_SIZE) & ~PAGE_MASK;
|
|
vm_ooffset_t 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;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
if (bp->b_flags & B_VMIO) {
|
|
int i;
|
|
int n;
|
|
|
|
/*
|
|
* 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);
|
|
|
|
for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
|
|
vm_page_t 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;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* vfs_bio_clrbuf:
|
|
*
|
|
* clear a buffer. This routine essentially fakes an I/O, so we need
|
|
* to clear B_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, mask = 0;
|
|
caddr_t sa, ea;
|
|
if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) {
|
|
bp->b_flags &= ~(B_INVAL|B_ERROR);
|
|
if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
|
|
(bp->b_offset & PAGE_MASK) == 0) {
|
|
mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
|
|
if (((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
|
|
((bp->b_pages[0]->valid & mask) != mask)) {
|
|
bzero(bp->b_data, bp->b_bufsize);
|
|
}
|
|
bp->b_pages[0]->valid |= mask;
|
|
bp->b_resid = 0;
|
|
return;
|
|
}
|
|
ea = sa = bp->b_data;
|
|
for(i=0;i<bp->b_npages;i++,sa=ea) {
|
|
int j = ((u_long)sa & PAGE_MASK) / DEV_BSIZE;
|
|
ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
|
|
ea = (caddr_t)ulmin((u_long)ea,
|
|
(u_long)bp->b_data + bp->b_bufsize);
|
|
mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
|
|
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;
|
|
vm_page_flag_clear(bp->b_pages[i], PG_ZERO);
|
|
}
|
|
bp->b_resid = 0;
|
|
} else {
|
|
clrbuf(bp);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* vm_hold_load_pages and vm_hold_unload pages get pages into
|
|
* a buffers address space. The pages are anonymous and are
|
|
* not associated with a file object.
|
|
*/
|
|
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;
|
|
|
|
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
|
|
|
|
tryagain:
|
|
|
|
p = vm_page_alloc(kernel_object,
|
|
((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT),
|
|
VM_ALLOC_NORMAL);
|
|
if (!p) {
|
|
vm_pageout_deficit += (to - from) >> PAGE_SHIFT;
|
|
VM_WAIT;
|
|
goto tryagain;
|
|
}
|
|
vm_page_wire(p);
|
|
p->valid = VM_PAGE_BITS_ALL;
|
|
vm_page_flag_clear(p, PG_ZERO);
|
|
pmap_kenter(pg, VM_PAGE_TO_PHYS(p));
|
|
bp->b_pages[index] = p;
|
|
vm_page_wakeup(p);
|
|
}
|
|
bp->b_npages = index;
|
|
}
|
|
|
|
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;
|
|
|
|
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
|
|
p = bp->b_pages[index];
|
|
if (p && (index < bp->b_npages)) {
|
|
#if !defined(MAX_PERF)
|
|
if (p->busy) {
|
|
printf("vm_hold_free_pages: blkno: %d, lblkno: %d\n",
|
|
bp->b_blkno, bp->b_lblkno);
|
|
}
|
|
#endif
|
|
bp->b_pages[index] = NULL;
|
|
pmap_kremove(pg);
|
|
vm_page_busy(p);
|
|
vm_page_unwire(p, 0);
|
|
vm_page_free(p);
|
|
}
|
|
}
|
|
bp->b_npages = newnpages;
|
|
}
|
|
|
|
|
|
#include "opt_ddb.h"
|
|
#ifdef DDB
|
|
#include <ddb/ddb.h>
|
|
|
|
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\nb_dev = (%d,%d), b_data = %p, "
|
|
"b_blkno = %d, b_pblkno = %d\n",
|
|
bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
|
|
major(bp->b_dev), minor(bp->b_dev),
|
|
bp->b_data, bp->b_blkno, bp->b_pblkno);
|
|
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 */
|