File: [local] / src / sys / kern / vfs_bio.c (download)
Revision 1.213, Sat Feb 3 18:51:58 2024 UTC (4 months ago) by beck
Branch: MAIN
CVS Tags: OPENBSD_7_5_BASE, OPENBSD_7_5, HEAD
Changes since 1.212: +1 -28 lines
Remove Softdep.
Softdep has been a no-op for some time now, this removes it to get
it out of the way.
Flensing mostly done in Talinn, with some help from krw@
ok deraadt@
|
/* $OpenBSD: vfs_bio.c,v 1.213 2024/02/03 18:51:58 beck Exp $ */
/* $NetBSD: vfs_bio.c,v 1.44 1996/06/11 11:15:36 pk Exp $ */
/*
* Copyright (c) 1994 Christopher G. Demetriou
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)vfs_bio.c 8.6 (Berkeley) 1/11/94
*/
/*
* Some references:
* Bach: The Design of the UNIX Operating System (Prentice Hall, 1986)
* Leffler, et al.: The Design and Implementation of the 4.3BSD
* UNIX Operating System (Addison Welley, 1989)
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/specdev.h>
#include <sys/tracepoint.h>
#include <uvm/uvm_extern.h>
/* XXX Should really be in buf.h, but for uvm_constraint_range.. */
int buf_realloc_pages(struct buf *, struct uvm_constraint_range *, int);
struct uvm_constraint_range high_constraint;
int fliphigh;
int nobuffers;
int needbuffer;
/* private bufcache functions */
void bufcache_init(void);
void bufcache_adjust(void);
struct buf *bufcache_gethighcleanbuf(void);
struct buf *bufcache_getdmacleanbuf(void);
/*
* Buffer pool for I/O buffers.
*/
struct pool bufpool;
struct bufhead bufhead = LIST_HEAD_INITIALIZER(bufhead);
void buf_put(struct buf *);
struct buf *bio_doread(struct vnode *, daddr_t, int, int);
struct buf *buf_get(struct vnode *, daddr_t, size_t);
void bread_cluster_callback(struct buf *);
int64_t bufcache_recover_dmapages(int discard, int64_t howmany);
static struct buf *incore_locked(struct vnode *vp, daddr_t blkno);
struct bcachestats bcstats; /* counters */
long lodirtypages; /* dirty page count low water mark */
long hidirtypages; /* dirty page count high water mark */
long targetpages; /* target number of pages for cache size */
long buflowpages; /* smallest size cache allowed */
long bufhighpages; /* largest size cache allowed */
long bufbackpages; /* minimum number of pages we shrink when asked to */
vsize_t bufkvm;
struct proc *cleanerproc;
int bd_req; /* Sleep point for cleaner daemon. */
#define NUM_CACHES 2
#define DMA_CACHE 0
struct bufcache cleancache[NUM_CACHES];
struct bufqueue dirtyqueue;
void
buf_put(struct buf *bp)
{
splassert(IPL_BIO);
#ifdef DIAGNOSTIC
if (bp->b_pobj != NULL)
KASSERT(bp->b_bufsize > 0);
if (ISSET(bp->b_flags, B_DELWRI))
panic("buf_put: releasing dirty buffer");
if (bp->b_freelist.tqe_next != NOLIST &&
bp->b_freelist.tqe_next != (void *)-1)
panic("buf_put: still on the free list");
if (bp->b_vnbufs.le_next != NOLIST &&
bp->b_vnbufs.le_next != (void *)-1)
panic("buf_put: still on the vnode list");
#endif
LIST_REMOVE(bp, b_list);
bcstats.numbufs--;
if (buf_dealloc_mem(bp) != 0)
return;
pool_put(&bufpool, bp);
}
/*
* Initialize buffers and hash links for buffers.
*/
void
bufinit(void)
{
u_int64_t dmapages;
u_int64_t highpages;
dmapages = uvm_pagecount(&dma_constraint);
/* take away a guess at how much of this the kernel will consume */
dmapages -= (atop(physmem) - atop(uvmexp.free));
/* See if we have memory above the dma accessible region. */
high_constraint.ucr_low = dma_constraint.ucr_high;
high_constraint.ucr_high = no_constraint.ucr_high;
if (high_constraint.ucr_low != high_constraint.ucr_high)
high_constraint.ucr_low++;
highpages = uvm_pagecount(&high_constraint);
/*
* Do we have any significant amount of high memory above
* the DMA region? if so enable moving buffers there, if not,
* don't bother.
*/
if (highpages > dmapages / 4)
fliphigh = 1;
else
fliphigh = 0;
/*
* If MD code doesn't say otherwise, use up to 10% of DMA'able
* memory for buffers.
*/
if (bufcachepercent == 0)
bufcachepercent = 10;
/*
* XXX these values and their same use in kern_sysctl
* need to move into buf.h
*/
KASSERT(bufcachepercent <= 90);
KASSERT(bufcachepercent >= 5);
if (bufpages == 0)
bufpages = dmapages * bufcachepercent / 100;
if (bufpages < BCACHE_MIN)
bufpages = BCACHE_MIN;
KASSERT(bufpages < dmapages);
bufhighpages = bufpages;
/*
* Set the base backoff level for the buffer cache. We will
* not allow uvm to steal back more than this number of pages.
*/
buflowpages = dmapages * 5 / 100;
if (buflowpages < BCACHE_MIN)
buflowpages = BCACHE_MIN;
/*
* set bufbackpages to 100 pages, or 10 percent of the low water mark
* if we don't have that many pages.
*/
bufbackpages = buflowpages * 10 / 100;
if (bufbackpages > 100)
bufbackpages = 100;
/*
* If the MD code does not say otherwise, reserve 10% of kva
* space for mapping buffers.
*/
if (bufkvm == 0)
bufkvm = VM_KERNEL_SPACE_SIZE / 10;
/*
* Don't use more than twice the amount of bufpages for mappings.
* It's twice since we map things sparsely.
*/
if (bufkvm > bufpages * PAGE_SIZE)
bufkvm = bufpages * PAGE_SIZE;
/*
* Round bufkvm to MAXPHYS because we allocate chunks of va space
* in MAXPHYS chunks.
*/
bufkvm &= ~(MAXPHYS - 1);
pool_init(&bufpool, sizeof(struct buf), 0, IPL_BIO, 0, "bufpl", NULL);
bufcache_init();
/*
* hmm - bufkvm is an argument because it's static, while
* bufpages is global because it can change while running.
*/
buf_mem_init(bufkvm);
/*
* Set the dirty page high water mark to be less than the low
* water mark for pages in the buffer cache. This ensures we
* can always back off by throwing away clean pages, and give
* ourselves a chance to write out the dirty pages eventually.
*/
hidirtypages = (buflowpages / 4) * 3;
lodirtypages = buflowpages / 2;
/*
* We are allowed to use up to the reserve.
*/
targetpages = bufpages - RESERVE_PAGES;
}
/*
* Change cachepct
*/
void
bufadjust(int newbufpages)
{
int s;
int64_t npages;
if (newbufpages < buflowpages)
newbufpages = buflowpages;
s = splbio();
bufpages = newbufpages;
/*
* We are allowed to use up to the reserve
*/
targetpages = bufpages - RESERVE_PAGES;
npages = bcstats.dmapages - targetpages;
/*
* Shrinking the cache happens here only if someone has manually
* adjusted bufcachepercent - or the pagedaemon has told us
* to give back memory *now* - so we give it all back.
*/
if (bcstats.dmapages > targetpages)
(void) bufcache_recover_dmapages(0, bcstats.dmapages - targetpages);
bufcache_adjust();
/*
* Wake up the cleaner if we have lots of dirty pages,
* or if we are getting low on buffer cache kva.
*/
if ((UNCLEAN_PAGES >= hidirtypages) ||
bcstats.kvaslots_avail <= 2 * RESERVE_SLOTS)
wakeup(&bd_req);
splx(s);
}
/*
* Make the buffer cache back off from cachepct.
*/
int
bufbackoff(struct uvm_constraint_range *range, long size)
{
/*
* Back off "size" buffer cache pages. Called by the page
* daemon to consume buffer cache pages rather than scanning.
*
* It returns 0 to the pagedaemon to indicate that it has
* succeeded in freeing enough pages. It returns -1 to
* indicate that it could not and the pagedaemon should take
* other measures.
*
*/
long pdelta, oldbufpages;
/*
* If we will accept high memory for this backoff
* try to steal it from the high memory buffer cache.
*/
if (range != NULL && range->ucr_high > dma_constraint.ucr_high) {
struct buf *bp;
int64_t start = bcstats.numbufpages, recovered = 0;
int s = splbio();
while ((recovered < size) &&
(bp = bufcache_gethighcleanbuf())) {
bufcache_take(bp);
if (bp->b_vp) {
RBT_REMOVE(buf_rb_bufs,
&bp->b_vp->v_bufs_tree, bp);
brelvp(bp);
}
buf_put(bp);
recovered = start - bcstats.numbufpages;
}
bufcache_adjust();
splx(s);
/* If we got enough, return success */
if (recovered >= size)
return 0;
/*
* If we needed only memory above DMA,
* return failure
*/
if (range->ucr_low > dma_constraint.ucr_high)
return -1;
/* Otherwise get the rest from DMA */
size -= recovered;
}
/*
* XXX Otherwise do the dma memory cache dance. this needs
* refactoring later to get rid of 'bufpages'
*/
/*
* Back off by at least bufbackpages. If the page daemon gave us
* a larger size, back off by that much.
*/
pdelta = (size > bufbackpages) ? size : bufbackpages;
if (bufpages <= buflowpages)
return(-1);
if (bufpages - pdelta < buflowpages)
pdelta = bufpages - buflowpages;
oldbufpages = bufpages;
bufadjust(bufpages - pdelta);
if (oldbufpages - bufpages < size)
return (-1); /* we did not free what we were asked */
else
return(0);
}
/*
* Opportunistically flip a buffer into high memory. Will move the buffer
* if memory is available without sleeping, and return 0, otherwise will
* fail and return -1 with the buffer unchanged.
*/
int
buf_flip_high(struct buf *bp)
{
int ret = -1;
KASSERT(ISSET(bp->b_flags, B_BC));
KASSERT(ISSET(bp->b_flags, B_DMA));
KASSERT(bp->cache == DMA_CACHE);
KASSERT(fliphigh);
splassert(IPL_BIO);
/* Attempt to move the buffer to high memory if we can */
if (buf_realloc_pages(bp, &high_constraint, UVM_PLA_NOWAIT) == 0) {
KASSERT(!ISSET(bp->b_flags, B_DMA));
bcstats.highflips++;
ret = 0;
} else
bcstats.highflops++;
return ret;
}
/*
* Flip a buffer to dma reachable memory, when we need it there for
* I/O. This can sleep since it will wait for memory allocation in the
* DMA reachable area since we have to have the buffer there to proceed.
*/
void
buf_flip_dma(struct buf *bp)
{
KASSERT(ISSET(bp->b_flags, B_BC));
KASSERT(ISSET(bp->b_flags, B_BUSY));
KASSERT(bp->cache < NUM_CACHES);
splassert(IPL_BIO);
if (!ISSET(bp->b_flags, B_DMA)) {
/* move buf to dma reachable memory */
(void) buf_realloc_pages(bp, &dma_constraint, UVM_PLA_WAITOK);
KASSERT(ISSET(bp->b_flags, B_DMA));
bcstats.dmaflips++;
}
if (bp->cache > DMA_CACHE) {
CLR(bp->b_flags, B_COLD);
CLR(bp->b_flags, B_WARM);
bp->cache = DMA_CACHE;
}
}
struct buf *
bio_doread(struct vnode *vp, daddr_t blkno, int size, int async)
{
struct buf *bp;
struct mount *mp;
bp = getblk(vp, blkno, size, 0, INFSLP);
/*
* If buffer does not have valid data, start a read.
* Note that if buffer is B_INVAL, getblk() won't return it.
* Therefore, it's valid if its I/O has completed or been delayed.
*/
if (!ISSET(bp->b_flags, (B_DONE | B_DELWRI))) {
SET(bp->b_flags, B_READ | async);
bcstats.pendingreads++;
bcstats.numreads++;
VOP_STRATEGY(bp->b_vp, bp);
/* Pay for the read. */
curproc->p_ru.ru_inblock++; /* XXX */
} else if (async) {
brelse(bp);
}
mp = vp->v_type == VBLK ? vp->v_specmountpoint : vp->v_mount;
/*
* Collect statistics on synchronous and asynchronous reads.
* Reads from block devices are charged to their associated
* filesystem (if any).
*/
if (mp != NULL) {
if (async == 0)
mp->mnt_stat.f_syncreads++;
else
mp->mnt_stat.f_asyncreads++;
}
return (bp);
}
/*
* Read a disk block.
* This algorithm described in Bach (p.54).
*/
int
bread(struct vnode *vp, daddr_t blkno, int size, struct buf **bpp)
{
struct buf *bp;
/* Get buffer for block. */
bp = *bpp = bio_doread(vp, blkno, size, 0);
/* Wait for the read to complete, and return result. */
return (biowait(bp));
}
/*
* Read-ahead multiple disk blocks. The first is sync, the rest async.
* Trivial modification to the breada algorithm presented in Bach (p.55).
*/
int
breadn(struct vnode *vp, daddr_t blkno, int size, daddr_t rablks[],
int rasizes[], int nrablks, struct buf **bpp)
{
struct buf *bp;
int i;
bp = *bpp = bio_doread(vp, blkno, size, 0);
/*
* For each of the read-ahead blocks, start a read, if necessary.
*/
for (i = 0; i < nrablks; i++) {
/* If it's in the cache, just go on to next one. */
if (incore(vp, rablks[i]))
continue;
/* Get a buffer for the read-ahead block */
(void) bio_doread(vp, rablks[i], rasizes[i], B_ASYNC);
}
/* Otherwise, we had to start a read for it; wait until it's valid. */
return (biowait(bp));
}
/*
* Called from interrupt context.
*/
void
bread_cluster_callback(struct buf *bp)
{
struct buf **xbpp = bp->b_saveaddr;
int i;
if (xbpp[1] != NULL) {
size_t newsize = xbpp[1]->b_bufsize;
/*
* Shrink this buffer's mapping to only cover its part of
* the total I/O.
*/
buf_fix_mapping(bp, newsize);
bp->b_bcount = newsize;
}
/* Invalidate read-ahead buffers if read short */
if (bp->b_resid > 0) {
for (i = 1; xbpp[i] != NULL; i++)
continue;
for (i = i - 1; i != 0; i--) {
if (xbpp[i]->b_bufsize <= bp->b_resid) {
bp->b_resid -= xbpp[i]->b_bufsize;
SET(xbpp[i]->b_flags, B_INVAL);
} else if (bp->b_resid > 0) {
bp->b_resid = 0;
SET(xbpp[i]->b_flags, B_INVAL);
} else
break;
}
}
for (i = 1; xbpp[i] != NULL; i++) {
if (ISSET(bp->b_flags, B_ERROR))
SET(xbpp[i]->b_flags, B_INVAL | B_ERROR);
/*
* Move the pages from the master buffer's uvm object
* into the individual buffer's uvm objects.
*/
struct uvm_object *newobj = &xbpp[i]->b_uobj;
struct uvm_object *oldobj = &bp->b_uobj;
int page;
uvm_obj_init(newobj, &bufcache_pager, 1);
for (page = 0; page < atop(xbpp[i]->b_bufsize); page++) {
struct vm_page *pg = uvm_pagelookup(oldobj,
xbpp[i]->b_poffs + ptoa(page));
KASSERT(pg != NULL);
KASSERT(pg->wire_count == 1);
uvm_pagerealloc(pg, newobj, xbpp[i]->b_poffs + ptoa(page));
}
xbpp[i]->b_pobj = newobj;
biodone(xbpp[i]);
}
free(xbpp, M_TEMP, (i + 1) * sizeof(*xbpp));
if (ISSET(bp->b_flags, B_ASYNC)) {
brelse(bp);
} else {
CLR(bp->b_flags, B_WANTED);
wakeup(bp);
}
}
/*
* Read-ahead multiple disk blocks, but make sure only one (big) I/O
* request is sent to the disk.
* XXX This should probably be dropped and breadn should instead be optimized
* XXX to do fewer I/O requests.
*/
int
bread_cluster(struct vnode *vp, daddr_t blkno, int size, struct buf **rbpp)
{
struct buf *bp, **xbpp;
int howmany, maxra, i, inc;
daddr_t sblkno;
*rbpp = bio_doread(vp, blkno, size, 0);
/*
* If the buffer is in the cache skip any I/O operation.
*/
if (ISSET((*rbpp)->b_flags, B_CACHE))
goto out;
if (size != round_page(size))
goto out;
if (VOP_BMAP(vp, blkno + 1, NULL, &sblkno, &maxra))
goto out;
maxra++;
if (sblkno == -1 || maxra < 2)
goto out;
howmany = MAXPHYS / size;
if (howmany > maxra)
howmany = maxra;
xbpp = mallocarray(howmany + 1, sizeof(*xbpp), M_TEMP, M_NOWAIT);
if (xbpp == NULL)
goto out;
for (i = howmany - 1; i >= 0; i--) {
size_t sz;
/*
* First buffer allocates big enough size to cover what
* all the other buffers need.
*/
sz = i == 0 ? howmany * size : 0;
xbpp[i] = buf_get(vp, blkno + i + 1, sz);
if (xbpp[i] == NULL) {
for (++i; i < howmany; i++) {
SET(xbpp[i]->b_flags, B_INVAL);
brelse(xbpp[i]);
}
free(xbpp, M_TEMP, (howmany + 1) * sizeof(*xbpp));
goto out;
}
}
bp = xbpp[0];
xbpp[howmany] = NULL;
inc = btodb(size);
for (i = 1; i < howmany; i++) {
bcstats.pendingreads++;
bcstats.numreads++;
/*
* We set B_DMA here because bp above will be B_DMA,
* and we are playing buffer slice-n-dice games from
* the memory allocated in bp.
*/
SET(xbpp[i]->b_flags, B_DMA | B_READ | B_ASYNC);
xbpp[i]->b_blkno = sblkno + (i * inc);
xbpp[i]->b_bufsize = xbpp[i]->b_bcount = size;
xbpp[i]->b_data = NULL;
xbpp[i]->b_pobj = bp->b_pobj;
xbpp[i]->b_poffs = bp->b_poffs + (i * size);
}
KASSERT(bp->b_lblkno == blkno + 1);
KASSERT(bp->b_vp == vp);
bp->b_blkno = sblkno;
SET(bp->b_flags, B_READ | B_ASYNC | B_CALL);
bp->b_saveaddr = (void *)xbpp;
bp->b_iodone = bread_cluster_callback;
bcstats.pendingreads++;
bcstats.numreads++;
VOP_STRATEGY(bp->b_vp, bp);
curproc->p_ru.ru_inblock++;
out:
return (biowait(*rbpp));
}
/*
* Block write. Described in Bach (p.56)
*/
int
bwrite(struct buf *bp)
{
int rv, async, wasdelayed, s;
struct vnode *vp;
struct mount *mp;
vp = bp->b_vp;
if (vp != NULL)
mp = vp->v_type == VBLK? vp->v_specmountpoint : vp->v_mount;
else
mp = NULL;
/*
* Remember buffer type, to switch on it later. If the write was
* synchronous, but the file system was mounted with MNT_ASYNC,
* convert it to a delayed write.
* XXX note that this relies on delayed tape writes being converted
* to async, not sync writes (which is safe, but ugly).
*/
async = ISSET(bp->b_flags, B_ASYNC);
if (!async && mp && ISSET(mp->mnt_flag, MNT_ASYNC)) {
/*
* Don't convert writes from VND on async filesystems
* that already have delayed writes in the upper layer.
*/
if (!ISSET(bp->b_flags, B_NOCACHE)) {
bdwrite(bp);
return (0);
}
}
/*
* Collect statistics on synchronous and asynchronous writes.
* Writes to block devices are charged to their associated
* filesystem (if any).
*/
if (mp != NULL) {
if (async)
mp->mnt_stat.f_asyncwrites++;
else
mp->mnt_stat.f_syncwrites++;
}
bcstats.pendingwrites++;
bcstats.numwrites++;
wasdelayed = ISSET(bp->b_flags, B_DELWRI);
CLR(bp->b_flags, (B_READ | B_DONE | B_ERROR | B_DELWRI));
s = splbio();
/*
* If not synchronous, pay for the I/O operation and make
* sure the buf is on the correct vnode queue. We have
* to do this now, because if we don't, the vnode may not
* be properly notified that its I/O has completed.
*/
if (wasdelayed) {
reassignbuf(bp);
} else
curproc->p_ru.ru_oublock++;
/* Initiate disk write. Make sure the appropriate party is charged. */
bp->b_vp->v_numoutput++;
buf_flip_dma(bp);
SET(bp->b_flags, B_WRITEINPROG);
splx(s);
VOP_STRATEGY(bp->b_vp, bp);
/*
* If the queue is above the high water mark, wait till
* the number of outstanding write bufs drops below the low
* water mark.
*/
if (bp->b_bq)
bufq_wait(bp->b_bq);
if (async)
return (0);
/*
* If I/O was synchronous, wait for it to complete.
*/
rv = biowait(bp);
/* Release the buffer. */
brelse(bp);
return (rv);
}
/*
* Delayed write.
*
* The buffer is marked dirty, but is not queued for I/O.
* This routine should be used when the buffer is expected
* to be modified again soon, typically a small write that
* partially fills a buffer.
*
* NB: magnetic tapes cannot be delayed; they must be
* written in the order that the writes are requested.
*
* Described in Leffler, et al. (pp. 208-213).
*/
void
bdwrite(struct buf *bp)
{
int s;
/*
* If the block hasn't been seen before:
* (1) Mark it as having been seen,
* (2) Charge for the write.
* (3) Make sure it's on its vnode's correct block list,
* (4) If a buffer is rewritten, move it to end of dirty list
*/
if (!ISSET(bp->b_flags, B_DELWRI)) {
SET(bp->b_flags, B_DELWRI);
s = splbio();
buf_flip_dma(bp);
reassignbuf(bp);
splx(s);
curproc->p_ru.ru_oublock++; /* XXX */
}
/* The "write" is done, so mark and release the buffer. */
CLR(bp->b_flags, B_NEEDCOMMIT);
CLR(bp->b_flags, B_NOCACHE); /* Must cache delayed writes */
SET(bp->b_flags, B_DONE);
brelse(bp);
}
/*
* Asynchronous block write; just an asynchronous bwrite().
*/
void
bawrite(struct buf *bp)
{
SET(bp->b_flags, B_ASYNC);
VOP_BWRITE(bp);
}
/*
* Must be called at splbio()
*/
void
buf_dirty(struct buf *bp)
{
splassert(IPL_BIO);
#ifdef DIAGNOSTIC
if (!ISSET(bp->b_flags, B_BUSY))
panic("Trying to dirty buffer on freelist!");
#endif
if (ISSET(bp->b_flags, B_DELWRI) == 0) {
SET(bp->b_flags, B_DELWRI);
buf_flip_dma(bp);
reassignbuf(bp);
}
}
/*
* Must be called at splbio()
*/
void
buf_undirty(struct buf *bp)
{
splassert(IPL_BIO);
#ifdef DIAGNOSTIC
if (!ISSET(bp->b_flags, B_BUSY))
panic("Trying to undirty buffer on freelist!");
#endif
if (ISSET(bp->b_flags, B_DELWRI)) {
CLR(bp->b_flags, B_DELWRI);
reassignbuf(bp);
}
}
/*
* Release a buffer on to the free lists.
* Described in Bach (p. 46).
*/
void
brelse(struct buf *bp)
{
int s;
s = splbio();
if (bp->b_data != NULL)
KASSERT(bp->b_bufsize > 0);
/*
* Determine which queue the buffer should be on, then put it there.
*/
/* If it's not cacheable, or an error, mark it invalid. */
if (ISSET(bp->b_flags, (B_NOCACHE|B_ERROR)))
SET(bp->b_flags, B_INVAL);
/* If it's a write error, also mark the vnode as damaged. */
if (ISSET(bp->b_flags, B_ERROR) && !ISSET(bp->b_flags, B_READ)) {
if (bp->b_vp && bp->b_vp->v_type == VREG)
SET(bp->b_vp->v_bioflag, VBIOERROR);
}
if (ISSET(bp->b_flags, B_INVAL)) {
/*
* If the buffer is invalid, free it now rather than leaving
* it in a queue and wasting memory.
*/
if (ISSET(bp->b_flags, B_DELWRI)) {
CLR(bp->b_flags, B_DELWRI);
}
if (bp->b_vp) {
RBT_REMOVE(buf_rb_bufs, &bp->b_vp->v_bufs_tree, bp);
brelvp(bp);
}
bp->b_vp = NULL;
/*
* Wake up any processes waiting for _this_ buffer to
* become free. They are not allowed to grab it
* since it will be freed. But the only sleeper is
* getblk and it will restart the operation after
* sleep.
*/
if (ISSET(bp->b_flags, B_WANTED)) {
CLR(bp->b_flags, B_WANTED);
wakeup(bp);
}
buf_put(bp);
} else {
/*
* It has valid data. Put it on the end of the appropriate
* queue, so that it'll stick around for as long as possible.
*/
bufcache_release(bp);
/* Unlock the buffer. */
CLR(bp->b_flags, (B_AGE | B_ASYNC | B_NOCACHE | B_DEFERRED));
buf_release(bp);
/* Wake up any processes waiting for _this_ buffer to
* become free. */
if (ISSET(bp->b_flags, B_WANTED)) {
CLR(bp->b_flags, B_WANTED);
wakeup(bp);
}
if (bcstats.dmapages > targetpages)
(void) bufcache_recover_dmapages(0,
bcstats.dmapages - targetpages);
bufcache_adjust();
}
/* Wake up syncer and cleaner processes waiting for buffers. */
if (nobuffers) {
nobuffers = 0;
wakeup(&nobuffers);
}
/* Wake up any processes waiting for any buffer to become free. */
if (needbuffer && bcstats.dmapages < targetpages &&
bcstats.kvaslots_avail > RESERVE_SLOTS) {
needbuffer = 0;
wakeup(&needbuffer);
}
splx(s);
}
/*
* Determine if a block is in the cache. Just look on what would be its hash
* chain. If it's there, return a pointer to it, unless it's marked invalid.
*/
static struct buf *
incore_locked(struct vnode *vp, daddr_t blkno)
{
struct buf *bp;
struct buf b;
splassert(IPL_BIO);
/* Search buf lookup tree */
b.b_lblkno = blkno;
bp = RBT_FIND(buf_rb_bufs, &vp->v_bufs_tree, &b);
if (bp != NULL && ISSET(bp->b_flags, B_INVAL))
bp = NULL;
return (bp);
}
struct buf *
incore(struct vnode *vp, daddr_t blkno)
{
struct buf *bp;
int s;
s = splbio();
bp = incore_locked(vp, blkno);
splx(s);
return (bp);
}
/*
* Get a block of requested size that is associated with
* a given vnode and block offset. If it is found in the
* block cache, mark it as having been found, make it busy
* and return it. Otherwise, return an empty block of the
* correct size. It is up to the caller to ensure that the
* cached blocks be of the correct size.
*/
struct buf *
getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag,
uint64_t slptimeo)
{
struct buf *bp;
struct buf b;
int s, error;
/*
* XXX
* The following is an inlined version of 'incore()', but with
* the 'invalid' test moved to after the 'busy' test. It's
* necessary because there are some cases in which the NFS
* code sets B_INVAL prior to writing data to the server, but
* in which the buffers actually contain valid data. In this
* case, we can't allow the system to allocate a new buffer for
* the block until the write is finished.
*/
start:
s = splbio();
b.b_lblkno = blkno;
bp = RBT_FIND(buf_rb_bufs, &vp->v_bufs_tree, &b);
if (bp != NULL) {
if (ISSET(bp->b_flags, B_BUSY)) {
SET(bp->b_flags, B_WANTED);
error = tsleep_nsec(bp, slpflag | (PRIBIO + 1),
"getblk", slptimeo);
splx(s);
if (error)
return (NULL);
goto start;
}
if (!ISSET(bp->b_flags, B_INVAL)) {
bcstats.cachehits++;
SET(bp->b_flags, B_CACHE);
bufcache_take(bp);
buf_acquire(bp);
splx(s);
return (bp);
}
}
splx(s);
if ((bp = buf_get(vp, blkno, size)) == NULL)
goto start;
return (bp);
}
/*
* Get an empty, disassociated buffer of given size.
*/
struct buf *
geteblk(size_t size)
{
struct buf *bp;
while ((bp = buf_get(NULL, 0, size)) == NULL)
continue;
return (bp);
}
/*
* Allocate a buffer.
* If vp is given, put it into the buffer cache for that vnode.
* If size != 0, allocate memory and call buf_map().
* If there is already a buffer for the given vnode/blkno, return NULL.
*/
struct buf *
buf_get(struct vnode *vp, daddr_t blkno, size_t size)
{
struct buf *bp;
int poolwait = size == 0 ? PR_NOWAIT : PR_WAITOK;
int npages;
int s;
s = splbio();
if (size) {
/*
* Wake up the cleaner if we have lots of dirty pages,
* or if we are getting low on buffer cache kva.
*/
if (UNCLEAN_PAGES >= hidirtypages ||
bcstats.kvaslots_avail <= 2 * RESERVE_SLOTS)
wakeup(&bd_req);
npages = atop(round_page(size));
/*
* if our cache has been previously shrunk,
* allow it to grow again with use up to
* bufhighpages (cachepercent)
*/
if (bufpages < bufhighpages)
bufadjust(bufhighpages);
/*
* If we would go over the page target with our
* new allocation, free enough buffers first
* to stay at the target with our new allocation.
*/
if (bcstats.dmapages + npages > targetpages) {
(void) bufcache_recover_dmapages(0, npages);
bufcache_adjust();
}
/*
* If we get here, we tried to free the world down
* above, and couldn't get down - Wake the cleaner
* and wait for it to push some buffers out.
*/
if ((bcstats.dmapages + npages > targetpages ||
bcstats.kvaslots_avail <= RESERVE_SLOTS) &&
curproc != syncerproc && curproc != cleanerproc) {
wakeup(&bd_req);
needbuffer++;
tsleep_nsec(&needbuffer, PRIBIO, "needbuffer", INFSLP);
splx(s);
return (NULL);
}
if (bcstats.dmapages + npages > bufpages) {
/* cleaner or syncer */
nobuffers = 1;
tsleep_nsec(&nobuffers, PRIBIO, "nobuffers", INFSLP);
splx(s);
return (NULL);
}
}
bp = pool_get(&bufpool, poolwait|PR_ZERO);
if (bp == NULL) {
splx(s);
return (NULL);
}
bp->b_freelist.tqe_next = NOLIST;
bp->b_dev = NODEV;
bp->b_bcount = size;
buf_acquire_nomap(bp);
if (vp != NULL) {
/*
* We insert the buffer into the hash with B_BUSY set
* while we allocate pages for it. This way any getblk
* that happens while we allocate pages will wait for
* this buffer instead of starting its own buf_get.
*
* But first, we check if someone beat us to it.
*/
if (incore_locked(vp, blkno)) {
pool_put(&bufpool, bp);
splx(s);
return (NULL);
}
bp->b_blkno = bp->b_lblkno = blkno;
bgetvp(vp, bp);
if (RBT_INSERT(buf_rb_bufs, &vp->v_bufs_tree, bp))
panic("buf_get: dup lblk vp %p bp %p", vp, bp);
} else {
bp->b_vnbufs.le_next = NOLIST;
SET(bp->b_flags, B_INVAL);
bp->b_vp = NULL;
}
LIST_INSERT_HEAD(&bufhead, bp, b_list);
bcstats.numbufs++;
if (size) {
buf_alloc_pages(bp, round_page(size));
KASSERT(ISSET(bp->b_flags, B_DMA));
buf_map(bp);
}
SET(bp->b_flags, B_BC);
splx(s);
return (bp);
}
/*
* Buffer cleaning daemon.
*/
void
buf_daemon(void *arg)
{
struct buf *bp = NULL;
int s, pushed = 0;
s = splbio();
for (;;) {
if (bp == NULL || (pushed >= 16 &&
UNCLEAN_PAGES < hidirtypages &&
bcstats.kvaslots_avail > 2 * RESERVE_SLOTS)){
pushed = 0;
/*
* Wake up anyone who was waiting for buffers
* to be released.
*/
if (needbuffer) {
needbuffer = 0;
wakeup(&needbuffer);
}
tsleep_nsec(&bd_req, PRIBIO - 7, "cleaner", INFSLP);
}
while ((bp = bufcache_getdirtybuf())) {
TRACEPOINT(vfs, cleaner, bp->b_flags, pushed,
lodirtypages, hidirtypages);
if (UNCLEAN_PAGES < lodirtypages &&
bcstats.kvaslots_avail > 2 * RESERVE_SLOTS &&
pushed >= 16)
break;
bufcache_take(bp);
buf_acquire(bp);
splx(s);
if (ISSET(bp->b_flags, B_INVAL)) {
brelse(bp);
s = splbio();
continue;
}
#ifdef DIAGNOSTIC
if (!ISSET(bp->b_flags, B_DELWRI))
panic("Clean buffer on dirty queue");
#endif
bawrite(bp);
pushed++;
sched_pause(yield);
s = splbio();
}
}
}
/*
* Wait for operations on the buffer to complete.
* When they do, extract and return the I/O's error value.
*/
int
biowait(struct buf *bp)
{
int s;
KASSERT(!(bp->b_flags & B_ASYNC));
s = splbio();
while (!ISSET(bp->b_flags, B_DONE))
tsleep_nsec(bp, PRIBIO + 1, "biowait", INFSLP);
splx(s);
/* check for interruption of I/O (e.g. via NFS), then errors. */
if (ISSET(bp->b_flags, B_EINTR)) {
CLR(bp->b_flags, B_EINTR);
return (EINTR);
}
if (ISSET(bp->b_flags, B_ERROR))
return (bp->b_error ? bp->b_error : EIO);
else
return (0);
}
/*
* Mark I/O complete on a buffer.
*
* If a callback has been requested, e.g. the pageout
* daemon, do so. Otherwise, awaken waiting processes.
*
* [ Leffler, et al., says on p.247:
* "This routine wakes up the blocked process, frees the buffer
* for an asynchronous write, or, for a request by the pagedaemon
* process, invokes a procedure specified in the buffer structure" ]
*
* In real life, the pagedaemon (or other system processes) wants
* to do async stuff to, and doesn't want the buffer brelse()'d.
* (for swap pager, that puts swap buffers on the free lists (!!!),
* for the vn device, that puts malloc'd buffers on the free lists!)
*
* Must be called at splbio().
*/
void
biodone(struct buf *bp)
{
splassert(IPL_BIO);
if (ISSET(bp->b_flags, B_DONE))
panic("biodone already");
SET(bp->b_flags, B_DONE); /* note that it's done */
if (bp->b_bq)
bufq_done(bp->b_bq, bp);
if (!ISSET(bp->b_flags, B_READ)) {
CLR(bp->b_flags, B_WRITEINPROG);
vwakeup(bp->b_vp);
}
if (bcstats.numbufs &&
(!(ISSET(bp->b_flags, B_RAW) || ISSET(bp->b_flags, B_PHYS)))) {
if (!ISSET(bp->b_flags, B_READ)) {
bcstats.pendingwrites--;
} else
bcstats.pendingreads--;
}
if (ISSET(bp->b_flags, B_CALL)) { /* if necessary, call out */
CLR(bp->b_flags, B_CALL); /* but note callout done */
(*bp->b_iodone)(bp);
} else {
if (ISSET(bp->b_flags, B_ASYNC)) {/* if async, release it */
brelse(bp);
} else { /* or just wakeup the buffer */
CLR(bp->b_flags, B_WANTED);
wakeup(bp);
}
}
}
#ifdef DDB
void bcstats_print(int (*)(const char *, ...)
__attribute__((__format__(__kprintf__,1,2))));
/*
* bcstats_print: ddb hook to print interesting buffer cache counters
*/
void
bcstats_print(
int (*pr)(const char *, ...) __attribute__((__format__(__kprintf__,1,2))))
{
(*pr)("Current Buffer Cache status:\n");
(*pr)("numbufs %lld busymapped %lld, delwri %lld\n",
bcstats.numbufs, bcstats.busymapped, bcstats.delwribufs);
(*pr)("kvaslots %lld avail kva slots %lld\n",
bcstats.kvaslots, bcstats.kvaslots_avail);
(*pr)("bufpages %lld, dmapages %lld, dirtypages %lld\n",
bcstats.numbufpages, bcstats.dmapages, bcstats.numdirtypages);
(*pr)("pendingreads %lld, pendingwrites %lld\n",
bcstats.pendingreads, bcstats.pendingwrites);
(*pr)("highflips %lld, highflops %lld, dmaflips %lld\n",
bcstats.highflips, bcstats.highflops, bcstats.dmaflips);
}
#endif
void
buf_adjcnt(struct buf *bp, long ncount)
{
KASSERT(ncount <= bp->b_bufsize);
bp->b_bcount = ncount;
}
/* bufcache freelist code below */
/*
* Copyright (c) 2014 Ted Unangst <tedu@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* The code below implements a variant of the 2Q buffer cache algorithm by
* Johnson and Shasha.
*
* General Outline
* We divide the buffer cache into three working sets: current, previous,
* and long term. Each list is itself LRU and buffers get promoted and moved
* around between them. A buffer starts its life in the current working set.
* As time passes and newer buffers push it out, it will turn into the previous
* working set and is subject to recycling. But if it's accessed again from
* the previous working set, that's an indication that it's actually in the
* long term working set, so we promote it there. The separation of current
* and previous working sets prevents us from promoting a buffer that's only
* temporarily hot to the long term cache.
*
* The objective is to provide scan resistance by making the long term
* working set ineligible for immediate recycling, even as the current
* working set is rapidly turned over.
*
* Implementation
* The code below identifies the current, previous, and long term sets as
* hotqueue, coldqueue, and warmqueue. The hot and warm queues are capped at
* 1/3 of the total clean pages, after which point they start pushing their
* oldest buffers into coldqueue.
* A buf always starts out with neither WARM or COLD flags set (implying HOT).
* When released, it will be returned to the tail of the hotqueue list.
* When the hotqueue gets too large, the oldest hot buf will be moved to the
* coldqueue, with the B_COLD flag set. When a cold buf is released, we set
* the B_WARM flag and put it onto the warmqueue. Warm bufs are also
* directly returned to the end of the warmqueue. As with the hotqueue, when
* the warmqueue grows too large, B_WARM bufs are moved onto the coldqueue.
*
* Note that this design does still support large working sets, greater
* than the cap of hotqueue or warmqueue would imply. The coldqueue is still
* cached and has no maximum length. The hot and warm queues form a Y feeding
* into the coldqueue. Moving bufs between queues is constant time, so this
* design decays to one long warm->cold queue.
*
* In the 2Q paper, hotqueue and coldqueue are A1in and A1out. The warmqueue
* is Am. We always cache pages, as opposed to pointers to pages for A1.
*
* This implementation adds support for multiple 2q caches.
*
* If we have more than one 2q cache, as bufs fall off the cold queue
* for recycling, bufs that have been warm before (which retain the
* B_WARM flag in addition to B_COLD) can be put into the hot queue of
* a second level 2Q cache. buffers which are only B_COLD are
* recycled. Bufs falling off the last cache's cold queue are always
* recycled.
*
*/
/*
* this function is called when a hot or warm queue may have exceeded its
* size limit. it will move a buf to the coldqueue.
*/
int chillbufs(struct
bufcache *cache, struct bufqueue *queue, int64_t *queuepages);
void
bufcache_init(void)
{
int i;
for (i = 0; i < NUM_CACHES; i++) {
TAILQ_INIT(&cleancache[i].hotqueue);
TAILQ_INIT(&cleancache[i].coldqueue);
TAILQ_INIT(&cleancache[i].warmqueue);
}
TAILQ_INIT(&dirtyqueue);
}
/*
* if the buffer caches have shrunk, we may need to rebalance our queues.
*/
void
bufcache_adjust(void)
{
int i;
for (i = 0; i < NUM_CACHES; i++) {
while (chillbufs(&cleancache[i], &cleancache[i].warmqueue,
&cleancache[i].warmbufpages) ||
chillbufs(&cleancache[i], &cleancache[i].hotqueue,
&cleancache[i].hotbufpages))
continue;
}
}
/*
* Get a clean buffer from the cache. if "discard" is set do not promote
* previously warm buffers as normal, because we are tossing everything
* away such as in a hibernation
*/
struct buf *
bufcache_getcleanbuf(int cachenum, int discard)
{
struct buf *bp = NULL;
struct bufcache *cache = &cleancache[cachenum];
struct bufqueue * queue;
splassert(IPL_BIO);
/* try cold queue */
while ((bp = TAILQ_FIRST(&cache->coldqueue)) ||
(bp = TAILQ_FIRST(&cache->warmqueue)) ||
(bp = TAILQ_FIRST(&cache->hotqueue))) {
int64_t pages = atop(bp->b_bufsize);
struct bufcache *newcache;
if (discard || cachenum >= NUM_CACHES - 1) {
/* Victim selected, give it up */
return bp;
}
KASSERT(bp->cache == cachenum);
/*
* If this buffer was warm before, move it to
* the hot queue in the next cache
*/
if (fliphigh) {
/*
* If we are in the DMA cache, try to flip the
* buffer up high to move it on to the other
* caches. if we can't move the buffer to high
* memory without sleeping, we give it up and
* return it rather than fight for more memory
* against non buffer cache competitors.
*/
SET(bp->b_flags, B_BUSY);
if (bp->cache == 0 && buf_flip_high(bp) == -1) {
CLR(bp->b_flags, B_BUSY);
return bp;
}
CLR(bp->b_flags, B_BUSY);
}
/* Move the buffer to the hot queue in the next cache */
if (ISSET(bp->b_flags, B_COLD)) {
queue = &cache->coldqueue;
} else if (ISSET(bp->b_flags, B_WARM)) {
queue = &cache->warmqueue;
cache->warmbufpages -= pages;
} else {
queue = &cache->hotqueue;
cache->hotbufpages -= pages;
}
TAILQ_REMOVE(queue, bp, b_freelist);
cache->cachepages -= pages;
CLR(bp->b_flags, B_WARM);
CLR(bp->b_flags, B_COLD);
bp->cache++;
newcache= &cleancache[bp->cache];
newcache->cachepages += pages;
newcache->hotbufpages += pages;
chillbufs(newcache, &newcache->hotqueue,
&newcache->hotbufpages);
TAILQ_INSERT_TAIL(&newcache->hotqueue, bp, b_freelist);
}
return bp;
}
void
discard_buffer(struct buf *bp)
{
splassert(IPL_BIO);
bufcache_take(bp);
if (bp->b_vp) {
RBT_REMOVE(buf_rb_bufs,
&bp->b_vp->v_bufs_tree, bp);
brelvp(bp);
}
buf_put(bp);
}
int64_t
bufcache_recover_dmapages(int discard, int64_t howmany)
{
struct buf *bp = NULL;
struct bufcache *cache = &cleancache[DMA_CACHE];
struct bufqueue * queue;
int64_t recovered = 0;
splassert(IPL_BIO);
while ((recovered < howmany) &&
((bp = TAILQ_FIRST(&cache->coldqueue)) ||
(bp = TAILQ_FIRST(&cache->warmqueue)) ||
(bp = TAILQ_FIRST(&cache->hotqueue)))) {
int64_t pages = atop(bp->b_bufsize);
struct bufcache *newcache;
if (discard || DMA_CACHE >= NUM_CACHES - 1) {
discard_buffer(bp);
continue;
}
KASSERT(bp->cache == DMA_CACHE);
/*
* If this buffer was warm before, move it to
* the hot queue in the next cache
*/
/*
* One way or another, the pages for this
* buffer are leaving DMA memory
*/
recovered += pages;
if (!fliphigh) {
discard_buffer(bp);
continue;
}
/*
* If we are in the DMA cache, try to flip the
* buffer up high to move it on to the other
* caches. if we can't move the buffer to high
* memory without sleeping, we give it up
* now rather than fight for more memory
* against non buffer cache competitors.
*/
SET(bp->b_flags, B_BUSY);
if (bp->cache == 0 && buf_flip_high(bp) == -1) {
CLR(bp->b_flags, B_BUSY);
discard_buffer(bp);
continue;
}
CLR(bp->b_flags, B_BUSY);
/*
* Move the buffer to the hot queue in the next cache
*/
if (ISSET(bp->b_flags, B_COLD)) {
queue = &cache->coldqueue;
} else if (ISSET(bp->b_flags, B_WARM)) {
queue = &cache->warmqueue;
cache->warmbufpages -= pages;
} else {
queue = &cache->hotqueue;
cache->hotbufpages -= pages;
}
TAILQ_REMOVE(queue, bp, b_freelist);
cache->cachepages -= pages;
CLR(bp->b_flags, B_WARM);
CLR(bp->b_flags, B_COLD);
bp->cache++;
newcache= &cleancache[bp->cache];
newcache->cachepages += pages;
newcache->hotbufpages += pages;
chillbufs(newcache, &newcache->hotqueue,
&newcache->hotbufpages);
TAILQ_INSERT_TAIL(&newcache->hotqueue, bp, b_freelist);
}
return recovered;
}
struct buf *
bufcache_getcleanbuf_range(int start, int end, int discard)
{
int i, j = start, q = end;
struct buf *bp = NULL;
/*
* XXX in theory we could promote warm buffers into a previous queue
* so in the pathological case of where we go through all the caches
* without getting a buffer we have to start at the beginning again.
*/
while (j <= q) {
for (i = q; i >= j; i--)
if ((bp = bufcache_getcleanbuf(i, discard)))
return (bp);
j++;
}
return bp;
}
struct buf *
bufcache_gethighcleanbuf(void)
{
if (!fliphigh)
return NULL;
return bufcache_getcleanbuf_range(DMA_CACHE + 1, NUM_CACHES - 1, 0);
}
struct buf *
bufcache_getdmacleanbuf(void)
{
if (fliphigh)
return bufcache_getcleanbuf_range(DMA_CACHE, DMA_CACHE, 0);
return bufcache_getcleanbuf_range(DMA_CACHE, NUM_CACHES - 1, 0);
}
struct buf *
bufcache_getdirtybuf(void)
{
return TAILQ_FIRST(&dirtyqueue);
}
void
bufcache_take(struct buf *bp)
{
struct bufqueue *queue;
int64_t pages;
splassert(IPL_BIO);
KASSERT(ISSET(bp->b_flags, B_BC));
KASSERT(bp->cache >= DMA_CACHE);
KASSERT((bp->cache < NUM_CACHES));
pages = atop(bp->b_bufsize);
TRACEPOINT(vfs, bufcache_take, bp->b_flags, bp->cache, pages);
struct bufcache *cache = &cleancache[bp->cache];
if (!ISSET(bp->b_flags, B_DELWRI)) {
if (ISSET(bp->b_flags, B_COLD)) {
queue = &cache->coldqueue;
} else if (ISSET(bp->b_flags, B_WARM)) {
queue = &cache->warmqueue;
cache->warmbufpages -= pages;
} else {
queue = &cache->hotqueue;
cache->hotbufpages -= pages;
}
bcstats.numcleanpages -= pages;
cache->cachepages -= pages;
} else {
queue = &dirtyqueue;
bcstats.numdirtypages -= pages;
bcstats.delwribufs--;
}
TAILQ_REMOVE(queue, bp, b_freelist);
}
/* move buffers from a hot or warm queue to a cold queue in a cache */
int
chillbufs(struct bufcache *cache, struct bufqueue *queue, int64_t *queuepages)
{
struct buf *bp;
int64_t limit, pages;
/*
* We limit the hot queue to be small, with a max of 4096 pages.
* We limit the warm queue to half the cache size.
*
* We impose a minimum size of 96 to prevent too much "wobbling".
*/
if (queue == &cache->hotqueue)
limit = min(cache->cachepages / 20, 4096);
else if (queue == &cache->warmqueue)
limit = (cache->cachepages / 2);
else
panic("chillbufs: invalid queue");
if (*queuepages > 96 && *queuepages > limit) {
bp = TAILQ_FIRST(queue);
if (!bp)
panic("inconsistent bufpage counts");
pages = atop(bp->b_bufsize);
*queuepages -= pages;
TAILQ_REMOVE(queue, bp, b_freelist);
/* we do not clear B_WARM */
SET(bp->b_flags, B_COLD);
TAILQ_INSERT_TAIL(&cache->coldqueue, bp, b_freelist);
return 1;
}
return 0;
}
void
bufcache_release(struct buf *bp)
{
struct bufqueue *queue;
int64_t pages;
struct bufcache *cache = &cleancache[bp->cache];
KASSERT(ISSET(bp->b_flags, B_BC));
pages = atop(bp->b_bufsize);
TRACEPOINT(vfs, bufcache_rel, bp->b_flags, bp->cache, pages);
if (fliphigh) {
if (ISSET(bp->b_flags, B_DMA) && bp->cache > 0)
panic("B_DMA buffer release from cache %d",
bp->cache);
else if ((!ISSET(bp->b_flags, B_DMA)) && bp->cache == 0)
panic("Non B_DMA buffer release from cache %d",
bp->cache);
}
if (!ISSET(bp->b_flags, B_DELWRI)) {
int64_t *queuepages;
if (ISSET(bp->b_flags, B_WARM | B_COLD)) {
SET(bp->b_flags, B_WARM);
CLR(bp->b_flags, B_COLD);
queue = &cache->warmqueue;
queuepages = &cache->warmbufpages;
} else {
queue = &cache->hotqueue;
queuepages = &cache->hotbufpages;
}
*queuepages += pages;
bcstats.numcleanpages += pages;
cache->cachepages += pages;
chillbufs(cache, queue, queuepages);
} else {
queue = &dirtyqueue;
bcstats.numdirtypages += pages;
bcstats.delwribufs++;
}
TAILQ_INSERT_TAIL(queue, bp, b_freelist);
}
#ifdef HIBERNATE
/*
* Nuke the buffer cache from orbit when hibernating. We do not want to save
* any clean cache pages to swap and read them back. the original disk files
* are just as good.
*/
void
hibernate_suspend_bufcache(void)
{
struct buf *bp;
int s;
s = splbio();
/* Chuck away all the cache pages.. discard bufs, do not promote */
while ((bp = bufcache_getcleanbuf_range(DMA_CACHE, NUM_CACHES - 1, 1))) {
bufcache_take(bp);
if (bp->b_vp) {
RBT_REMOVE(buf_rb_bufs, &bp->b_vp->v_bufs_tree, bp);
brelvp(bp);
}
buf_put(bp);
}
splx(s);
}
void
hibernate_resume_bufcache(void)
{
/* XXX Nothing needed here for now */
}
#endif /* HIBERNATE */
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