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a7283d3213
freebsd/sys/kern/vfs_bio.c
Alan Cox a7283d3213 Add page locking to the vm_page_cow* functions. 
Push down the acquisition and release of the page queues lock into
vm_page_wire().

Reviewed by:	kib
2010-05-04 15:55:41 +00:00

4127 lines
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/*-
* Copyright (c) 2004 Poul-Henning Kamp
* Copyright (c) 1994,1997 John S. Dyson
* All rights reserved.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
/*
* this file contains a new buffer I/O scheme implementing a coherent
* VM object and buffer cache scheme. Pains have been taken to make
* sure that the performance degradation associated with schemes such
* as this is not realized.
*
* Author: John S. Dyson
* Significant help during the development and debugging phases
* had been provided by David Greenman, also of the FreeBSD core team.
*
* see man buf(9) for more info.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/conf.h>
#include <sys/buf.h>
#include <sys/devicestat.h>
#include <sys/eventhandler.h>
#include <sys/fail.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sysctl.h>
#include <sys/vmmeter.h>
#include <sys/vnode.h>
#include <geom/geom.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_pageout.h>
#include <vm/vm_page.h>
#include <vm/vm_object.h>
#include <vm/vm_extern.h>
#include <vm/vm_map.h>
#include "opt_compat.h"
#include "opt_directio.h"
#include "opt_swap.h"
static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer");
struct bio_ops bioops; /* I/O operation notification */
struct buf_ops buf_ops_bio = {
.bop_name = "buf_ops_bio",
.bop_write = bufwrite,
.bop_strategy = bufstrategy,
.bop_sync = bufsync,
.bop_bdflush = bufbdflush,
};
/*
* XXX buf is global because kern_shutdown.c and ffs_checkoverlap has
* carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c.
*/
struct buf *buf; /* buffer header pool */
static struct proc *bufdaemonproc;
static int inmem(struct vnode *vp, daddr_t blkno);
static void vm_hold_free_pages(struct buf *bp, vm_offset_t from,
vm_offset_t to);
static void vm_hold_load_pages(struct buf *bp, vm_offset_t from,
vm_offset_t to);
static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m);
static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off,
vm_page_t m);
static void vfs_clean_pages(struct buf *bp);
static void vfs_setdirty(struct buf *bp);
static void vfs_setdirty_locked_object(struct buf *bp);
static void vfs_vmio_release(struct buf *bp);
static int vfs_bio_clcheck(struct vnode *vp, int size,
daddr_t lblkno, daddr_t blkno);
static int buf_do_flush(struct vnode *vp);
static int flushbufqueues(struct vnode *, int, int);
static void buf_daemon(void);
static void bremfreel(struct buf *bp);
#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
static int sysctl_bufspace(SYSCTL_HANDLER_ARGS);
#endif
int vmiodirenable = TRUE;
SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0,
"Use the VM system for directory writes");
long runningbufspace;
SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0,
"Amount of presently outstanding async buffer io");
static long bufspace;
#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD,
&bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers");
#else
SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0,
"Virtual memory used for buffers");
#endif
static long maxbufspace;
SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0,
"Maximum allowed value of bufspace (including buf_daemon)");
static long bufmallocspace;
SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0,
"Amount of malloced memory for buffers");
static long maxbufmallocspace;
SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0,
"Maximum amount of malloced memory for buffers");
static long lobufspace;
SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0,
"Minimum amount of buffers we want to have");
long hibufspace;
SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0,
"Maximum allowed value of bufspace (excluding buf_daemon)");
static int bufreusecnt;
SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0,
"Number of times we have reused a buffer");
static int buffreekvacnt;
SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0,
"Number of times we have freed the KVA space from some buffer");
static int bufdefragcnt;
SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0,
"Number of times we have had to repeat buffer allocation to defragment");
static long lorunningspace;
SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0,
"Minimum preferred space used for in-progress I/O");
static long hirunningspace;
SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0,
"Maximum amount of space to use for in-progress I/O");
int dirtybufferflushes;
SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes,
0, "Number of bdwrite to bawrite conversions to limit dirty buffers");
int bdwriteskip;
SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip,
0, "Number of buffers supplied to bdwrite with snapshot deadlock risk");
int altbufferflushes;
SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes,
0, "Number of fsync flushes to limit dirty buffers");
static int recursiveflushes;
SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes,
0, "Number of flushes skipped due to being recursive");
static int numdirtybuffers;
SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0,
"Number of buffers that are dirty (has unwritten changes) at the moment");
static int lodirtybuffers;
SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0,
"How many buffers we want to have free before bufdaemon can sleep");
static int hidirtybuffers;
SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0,
"When the number of dirty buffers is considered severe");
int dirtybufthresh;
SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh,
0, "Number of bdwrite to bawrite conversions to clear dirty buffers");
static int numfreebuffers;
SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0,
"Number of free buffers");
static int lofreebuffers;
SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0,
"XXX Unused");
static int hifreebuffers;
SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
"XXX Complicatedly unused");
static int getnewbufcalls;
SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0,
"Number of calls to getnewbuf");
static int getnewbufrestarts;
SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0,
"Number of times getnewbuf has had to restart a buffer aquisition");
static int flushbufqtarget = 100;
SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0,
"Amount of work to do in flushbufqueues when helping bufdaemon");
static long notbufdflashes;
SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, &notbufdflashes, 0,
"Number of dirty buffer flushes done by the bufdaemon helpers");
/*
* Wakeup point for bufdaemon, as well as indicator of whether it is already
* active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it
* is idling.
*/
static int bd_request;
/*
* Request for the buf daemon to write more buffers than is indicated by
* lodirtybuf. This may be necessary to push out excess dependencies or
* defragment the address space where a simple count of the number of dirty
* buffers is insufficient to characterize the demand for flushing them.
*/
static int bd_speedupreq;
/*
* This lock synchronizes access to bd_request.
*/
static struct mtx bdlock;
/*
* bogus page -- for I/O to/from partially complete buffers
* this is a temporary solution to the problem, but it is not
* really that bad. it would be better to split the buffer
* for input in the case of buffers partially already in memory,
* but the code is intricate enough already.
*/
vm_page_t bogus_page;
/*
* Synchronization (sleep/wakeup) variable for active buffer space requests.
* Set when wait starts, cleared prior to wakeup().
* Used in runningbufwakeup() and waitrunningbufspace().
*/
static int runningbufreq;
/*
* This lock protects the runningbufreq and synchronizes runningbufwakeup and
* waitrunningbufspace().
*/
static struct mtx rbreqlock;
/*
* Synchronization (sleep/wakeup) variable for buffer requests.
* Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done
* by and/or.
* Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(),
* getnewbuf(), and getblk().
*/
static int needsbuffer;
/*
* Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
*/
static struct mtx nblock;
/*
* Definitions for the buffer free lists.
*/
#define BUFFER_QUEUES 6 /* number of free buffer queues */
#define QUEUE_NONE 0 /* on no queue */
#define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */
#define QUEUE_DIRTY 2 /* B_DELWRI buffers */
#define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */
#define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
#define QUEUE_EMPTY 5 /* empty buffer headers */
#define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
/* Queues for free buffers with various properties */
static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } };
/* Lock for the bufqueues */
static struct mtx bqlock;
/*
* Single global constant for BUF_WMESG, to avoid getting multiple references.
* buf_wmesg is referred from macros.
*/
const char *buf_wmesg = BUF_WMESG;
#define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */
#define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */
#define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */
#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
#if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \
defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7)
static int
sysctl_bufspace(SYSCTL_HANDLER_ARGS)
{
long lvalue;
int ivalue;
if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long))
return (sysctl_handle_long(oidp, arg1, arg2, req));
lvalue = *(long *)arg1;
if (lvalue > INT_MAX)
/* On overflow, still write out a long to trigger ENOMEM. */
return (sysctl_handle_long(oidp, &lvalue, 0, req));
ivalue = lvalue;
return (sysctl_handle_int(oidp, &ivalue, 0, req));
}
#endif
#ifdef DIRECTIO
extern void ffs_rawread_setup(void);
#endif /* DIRECTIO */
/*
* numdirtywakeup:
*
* If someone is blocked due to there being too many dirty buffers,
* and numdirtybuffers is now reasonable, wake them up.
*/
static __inline void
numdirtywakeup(int level)
{
if (numdirtybuffers <= level) {
mtx_lock(&nblock);
if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) {
needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH;
wakeup(&needsbuffer);
}
mtx_unlock(&nblock);
}
}
/*
* bufspacewakeup:
*
* Called when buffer space is potentially available for recovery.
* getnewbuf() will block on this flag when it is unable to free
* sufficient buffer space. Buffer space becomes recoverable when
* bp's get placed back in the queues.
*/
static __inline void
bufspacewakeup(void)
{
/*
* If someone is waiting for BUF space, wake them up. Even
* though we haven't freed the kva space yet, the waiting
* process will be able to now.
*/
mtx_lock(&nblock);
if (needsbuffer & VFS_BIO_NEED_BUFSPACE) {
needsbuffer &= ~VFS_BIO_NEED_BUFSPACE;
wakeup(&needsbuffer);
}
mtx_unlock(&nblock);
}
/*
* runningbufwakeup() - in-progress I/O accounting.
*
*/
void
runningbufwakeup(struct buf *bp)
{
if (bp->b_runningbufspace) {
atomic_subtract_long(&runningbufspace, bp->b_runningbufspace);
bp->b_runningbufspace = 0;
mtx_lock(&rbreqlock);
if (runningbufreq && runningbufspace <= lorunningspace) {
runningbufreq = 0;
wakeup(&runningbufreq);
}
mtx_unlock(&rbreqlock);
}
}
/*
* bufcountwakeup:
*
* Called when a buffer has been added to one of the free queues to
* account for the buffer and to wakeup anyone waiting for free buffers.
* This typically occurs when large amounts of metadata are being handled
* by the buffer cache ( else buffer space runs out first, usually ).
*/
static __inline void
bufcountwakeup(void)
{
atomic_add_int(&numfreebuffers, 1);
mtx_lock(&nblock);
if (needsbuffer) {
needsbuffer &= ~VFS_BIO_NEED_ANY;
if (numfreebuffers >= hifreebuffers)
needsbuffer &= ~VFS_BIO_NEED_FREE;
wakeup(&needsbuffer);
}
mtx_unlock(&nblock);
}
/*
* waitrunningbufspace()
*
* runningbufspace is a measure of the amount of I/O currently
* running. This routine is used in async-write situations to
* prevent creating huge backups of pending writes to a device.
* Only asynchronous writes are governed by this function.
*
* Reads will adjust runningbufspace, but will not block based on it.
* The read load has a side effect of reducing the allowed write load.
*
* This does NOT turn an async write into a sync write. It waits
* for earlier writes to complete and generally returns before the
* caller's write has reached the device.
*/
void
waitrunningbufspace(void)
{
mtx_lock(&rbreqlock);
while (runningbufspace > hirunningspace) {
++runningbufreq;
msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0);
}
mtx_unlock(&rbreqlock);
}
/*
* vfs_buf_test_cache:
*
* Called when a buffer is extended. This function clears the B_CACHE
* bit if the newly extended portion of the buffer does not contain
* valid data.
*/
static __inline
void
vfs_buf_test_cache(struct buf *bp,
vm_ooffset_t foff, vm_offset_t off, vm_offset_t size,
vm_page_t m)
{
VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
if (bp->b_flags & B_CACHE) {
int base = (foff + off) & PAGE_MASK;
if (vm_page_is_valid(m, base, size) == 0)
bp->b_flags &= ~B_CACHE;
}
}
/* Wake up the buffer daemon if necessary */
static __inline
void
bd_wakeup(int dirtybuflevel)
{
mtx_lock(&bdlock);
if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) {
bd_request = 1;
wakeup(&bd_request);
}
mtx_unlock(&bdlock);
}
/*
* bd_speedup - speedup the buffer cache flushing code
*/
void
bd_speedup(void)
{
int needwake;
mtx_lock(&bdlock);
needwake = 0;
if (bd_speedupreq == 0 || bd_request == 0)
needwake = 1;
bd_speedupreq = 1;
bd_request = 1;
if (needwake)
wakeup(&bd_request);
mtx_unlock(&bdlock);
}
/*
* Calculating buffer cache scaling values and reserve space for buffer
* headers. This is called during low level kernel initialization and
* may be called more then once. We CANNOT write to the memory area
* being reserved at this time.
*/
caddr_t
kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est)
{
int tuned_nbuf;
long maxbuf;
/*
* physmem_est is in pages. Convert it to kilobytes (assumes
* PAGE_SIZE is >= 1K)
*/
physmem_est = physmem_est * (PAGE_SIZE / 1024);
/*
* The nominal buffer size (and minimum KVA allocation) is BKVASIZE.
* For the first 64MB of ram nominally allocate sufficient buffers to
* cover 1/4 of our ram. Beyond the first 64MB allocate additional
* buffers to cover 1/10 of our ram over 64MB. When auto-sizing
* the buffer cache we limit the eventual kva reservation to
* maxbcache bytes.
*
* factor represents the 1/4 x ram conversion.
*/
if (nbuf == 0) {
int factor = 4 * BKVASIZE / 1024;
nbuf = 50;
if (physmem_est > 4096)
nbuf += min((physmem_est - 4096) / factor,
65536 / factor);
if (physmem_est > 65536)
nbuf += (physmem_est - 65536) * 2 / (factor * 5);
if (maxbcache && nbuf > maxbcache / BKVASIZE)
nbuf = maxbcache / BKVASIZE;
tuned_nbuf = 1;
} else
tuned_nbuf = 0;
/* XXX Avoid unsigned long overflows later on with maxbufspace. */
maxbuf = (LONG_MAX / 3) / BKVASIZE;
if (nbuf > maxbuf) {
if (!tuned_nbuf)
printf("Warning: nbufs lowered from %d to %ld\n", nbuf,
maxbuf);
nbuf = maxbuf;
}
/*
* swbufs are used as temporary holders for I/O, such as paging I/O.
* We have no less then 16 and no more then 256.
*/
nswbuf = max(min(nbuf/4, 256), 16);
#ifdef NSWBUF_MIN
if (nswbuf < NSWBUF_MIN)
nswbuf = NSWBUF_MIN;
#endif
#ifdef DIRECTIO
ffs_rawread_setup();
#endif
/*
* Reserve space for the buffer cache buffers
*/
swbuf = (void *)v;
v = (caddr_t)(swbuf + nswbuf);
buf = (void *)v;
v = (caddr_t)(buf + nbuf);
return(v);
}
/* Initialize the buffer subsystem. Called before use of any buffers. */
void
bufinit(void)
{
struct buf *bp;
int i;
mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF);
mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF);
mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
/* next, make a null set of free lists */
for (i = 0; i < BUFFER_QUEUES; i++)
TAILQ_INIT(&bufqueues[i]);
/* finally, initialize each buffer header and stick on empty q */
for (i = 0; i < nbuf; i++) {
bp = &buf[i];
bzero(bp, sizeof *bp);
bp->b_flags = B_INVAL; /* we're just an empty header */
bp->b_rcred = NOCRED;
bp->b_wcred = NOCRED;
bp->b_qindex = QUEUE_EMPTY;
bp->b_vflags = 0;
bp->b_xflags = 0;
LIST_INIT(&bp->b_dep);
BUF_LOCKINIT(bp);
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
}
/*
* maxbufspace is the absolute maximum amount of buffer space we are
* allowed to reserve in KVM and in real terms. The absolute maximum
* is nominally used by buf_daemon. hibufspace is the nominal maximum
* used by most other processes. The differential is required to
* ensure that buf_daemon is able to run when other processes might
* be blocked waiting for buffer space.
*
* maxbufspace is based on BKVASIZE. Allocating buffers larger then
* this may result in KVM fragmentation which is not handled optimally
* by the system.
*/
maxbufspace = (long)nbuf * BKVASIZE;
hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10);
lobufspace = hibufspace - MAXBSIZE;
lorunningspace = 512 * 1024;
hirunningspace = 1024 * 1024;
/*
* Limit the amount of malloc memory since it is wired permanently into
* the kernel space. Even though this is accounted for in the buffer
* allocation, we don't want the malloced region to grow uncontrolled.
* The malloc scheme improves memory utilization significantly on average
* (small) directories.
*/
maxbufmallocspace = hibufspace / 20;
/*
* Reduce the chance of a deadlock occuring by limiting the number
* of delayed-write dirty buffers we allow to stack up.
*/
hidirtybuffers = nbuf / 4 + 20;
dirtybufthresh = hidirtybuffers * 9 / 10;
numdirtybuffers = 0;
/*
* To support extreme low-memory systems, make sure hidirtybuffers cannot
* eat up all available buffer space. This occurs when our minimum cannot
* be met. We try to size hidirtybuffers to 3/4 our buffer space assuming
* BKVASIZE'd (8K) buffers.
*/
while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) {
hidirtybuffers >>= 1;
}
lodirtybuffers = hidirtybuffers / 2;
/*
* Try to keep the number of free buffers in the specified range,
* and give special processes (e.g. like buf_daemon) access to an
* emergency reserve.
*/
lofreebuffers = nbuf / 18 + 5;
hifreebuffers = 2 * lofreebuffers;
numfreebuffers = nbuf;
bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
}
/*
* bfreekva() - free the kva allocation for a buffer.
*
* Since this call frees up buffer space, we call bufspacewakeup().
*/
static void
bfreekva(struct buf *bp)
{
if (bp->b_kvasize) {
atomic_add_int(&buffreekvacnt, 1);
atomic_subtract_long(&bufspace, bp->b_kvasize);
vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase,
(vm_offset_t) bp->b_kvabase + bp->b_kvasize);
bp->b_kvasize = 0;
bufspacewakeup();
}
}
/*
* bremfree:
*
* Mark the buffer for removal from the appropriate free list in brelse.
*
*/
void
bremfree(struct buf *bp)
{
CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT((bp->b_flags & B_REMFREE) == 0,
("bremfree: buffer %p already marked for delayed removal.", bp));
KASSERT(bp->b_qindex != QUEUE_NONE,
("bremfree: buffer %p not on a queue.", bp));
BUF_ASSERT_HELD(bp);
bp->b_flags |= B_REMFREE;
/* Fixup numfreebuffers count. */
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
atomic_subtract_int(&numfreebuffers, 1);
}
/*
* bremfreef:
*
* Force an immediate removal from a free list. Used only in nfs when
* it abuses the b_freelist pointer.
*/
void
bremfreef(struct buf *bp)
{
mtx_lock(&bqlock);
bremfreel(bp);
mtx_unlock(&bqlock);
}
/*
* bremfreel:
*
* Removes a buffer from the free list, must be called with the
* bqlock held.
*/
static void
bremfreel(struct buf *bp)
{
CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_qindex != QUEUE_NONE,
("bremfreel: buffer %p not on a queue.", bp));
BUF_ASSERT_HELD(bp);
mtx_assert(&bqlock, MA_OWNED);
TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
bp->b_qindex = QUEUE_NONE;
/*
* If this was a delayed bremfree() we only need to remove the buffer
* from the queue and return the stats are already done.
*/
if (bp->b_flags & B_REMFREE) {
bp->b_flags &= ~B_REMFREE;
return;
}
/*
* Fixup numfreebuffers count. If the buffer is invalid or not
* delayed-write, the buffer was free and we must decrement
* numfreebuffers.
*/
if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0)
atomic_subtract_int(&numfreebuffers, 1);
}
/*
* Get a buffer with the specified data. Look in the cache first. We
* must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE
* is set, the buffer is valid and we do not have to do anything ( see
* getblk() ). This is really just a special case of breadn().
*/
int
bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred,
struct buf **bpp)
{
return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp));
}
/*
* Attempt to initiate asynchronous I/O on read-ahead blocks. We must
* clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set,
* the buffer is valid and we do not have to do anything.
*/
void
breada(struct vnode * vp, daddr_t * rablkno, int * rabsize,
int cnt, struct ucred * cred)
{
struct buf *rabp;
int i;
for (i = 0; i < cnt; i++, rablkno++, rabsize++) {
if (inmem(vp, *rablkno))
continue;
rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0);
if ((rabp->b_flags & B_CACHE) == 0) {
if (!TD_IS_IDLETHREAD(curthread))
curthread->td_ru.ru_inblock++;
rabp->b_flags |= B_ASYNC;
rabp->b_flags &= ~B_INVAL;
rabp->b_ioflags &= ~BIO_ERROR;
rabp->b_iocmd = BIO_READ;
if (rabp->b_rcred == NOCRED && cred != NOCRED)
rabp->b_rcred = crhold(cred);
vfs_busy_pages(rabp, 0);
BUF_KERNPROC(rabp);
rabp->b_iooffset = dbtob(rabp->b_blkno);
bstrategy(rabp);
} else {
brelse(rabp);
}
}
}
/*
* Operates like bread, but also starts asynchronous I/O on
* read-ahead blocks.
*/
int
breadn(struct vnode * vp, daddr_t blkno, int size,
daddr_t * rablkno, int *rabsize,
int cnt, struct ucred * cred, struct buf **bpp)
{
struct buf *bp;
int rv = 0, readwait = 0;
CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
*bpp = bp = getblk(vp, blkno, size, 0, 0, 0);
/* if not found in cache, do some I/O */
if ((bp->b_flags & B_CACHE) == 0) {
if (!TD_IS_IDLETHREAD(curthread))
curthread->td_ru.ru_inblock++;
bp->b_iocmd = BIO_READ;
bp->b_flags &= ~B_INVAL;
bp->b_ioflags &= ~BIO_ERROR;
if (bp->b_rcred == NOCRED && cred != NOCRED)
bp->b_rcred = crhold(cred);
vfs_busy_pages(bp, 0);
bp->b_iooffset = dbtob(bp->b_blkno);
bstrategy(bp);
++readwait;
}
breada(vp, rablkno, rabsize, cnt, cred);
if (readwait) {
rv = bufwait(bp);
}
return (rv);
}
/*
* Write, release buffer on completion. (Done by iodone
* if async). Do not bother writing anything if the buffer
* is invalid.
*
* Note that we set B_CACHE here, indicating that buffer is
* fully valid and thus cacheable. This is true even of NFS
* now so we set it generally. This could be set either here
* or in biodone() since the I/O is synchronous. We put it
* here.
*/
int
bufwrite(struct buf *bp)
{
int oldflags;
struct vnode *vp;
int vp_md;
CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
if (bp->b_flags & B_INVAL) {
brelse(bp);
return (0);
}
oldflags = bp->b_flags;
BUF_ASSERT_HELD(bp);
if (bp->b_pin_count > 0)
bunpin_wait(bp);
KASSERT(!(bp->b_vflags & BV_BKGRDINPROG),
("FFS background buffer should not get here %p", bp));
vp = bp->b_vp;
if (vp)
vp_md = vp->v_vflag & VV_MD;
else
vp_md = 0;
/* Mark the buffer clean */
bundirty(bp);
bp->b_flags &= ~B_DONE;
bp->b_ioflags &= ~BIO_ERROR;
bp->b_flags |= B_CACHE;
bp->b_iocmd = BIO_WRITE;
bufobj_wref(bp->b_bufobj);
vfs_busy_pages(bp, 1);
/*
* Normal bwrites pipeline writes
*/
bp->b_runningbufspace = bp->b_bufsize;
atomic_add_long(&runningbufspace, bp->b_runningbufspace);
if (!TD_IS_IDLETHREAD(curthread))
curthread->td_ru.ru_oublock++;
if (oldflags & B_ASYNC)
BUF_KERNPROC(bp);
bp->b_iooffset = dbtob(bp->b_blkno);
bstrategy(bp);
if ((oldflags & B_ASYNC) == 0) {
int rtval = bufwait(bp);
brelse(bp);
return (rtval);
} else {
/*
* don't allow the async write to saturate the I/O
* system. We will not deadlock here because
* we are blocking waiting for I/O that is already in-progress
* to complete. We do not block here if it is the update
* or syncer daemon trying to clean up as that can lead
* to deadlock.
*/
if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md)
waitrunningbufspace();
}
return (0);
}
void
bufbdflush(struct bufobj *bo, struct buf *bp)
{
struct buf *nbp;
if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) {
(void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread);
altbufferflushes++;
} else if (bo->bo_dirty.bv_cnt > dirtybufthresh) {
BO_LOCK(bo);
/*
* Try to find a buffer to flush.
*/
TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) {
if ((nbp->b_vflags & BV_BKGRDINPROG) ||
BUF_LOCK(nbp,
LK_EXCLUSIVE | LK_NOWAIT, NULL))
continue;
if (bp == nbp)
panic("bdwrite: found ourselves");
BO_UNLOCK(bo);
/* Don't countdeps with the bo lock held. */
if (buf_countdeps(nbp, 0)) {
BO_LOCK(bo);
BUF_UNLOCK(nbp);
continue;
}
if (nbp->b_flags & B_CLUSTEROK) {
vfs_bio_awrite(nbp);
} else {
bremfree(nbp);
bawrite(nbp);
}
dirtybufferflushes++;
break;
}
if (nbp == NULL)
BO_UNLOCK(bo);
}
}
/*
* Delayed write. (Buffer is marked dirty). Do not bother writing
* anything if the buffer is marked invalid.
*
* Note that since the buffer must be completely valid, we can safely
* set B_CACHE. In fact, we have to set B_CACHE here rather then in
* biodone() in order to prevent getblk from writing the buffer
* out synchronously.
*/
void
bdwrite(struct buf *bp)
{
struct thread *td = curthread;
struct vnode *vp;
struct bufobj *bo;
CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
BUF_ASSERT_HELD(bp);
if (bp->b_flags & B_INVAL) {
brelse(bp);
return;
}
/*
* If we have too many dirty buffers, don't create any more.
* If we are wildly over our limit, then force a complete
* cleanup. Otherwise, just keep the situation from getting
* out of control. Note that we have to avoid a recursive
* disaster and not try to clean up after our own cleanup!
*/
vp = bp->b_vp;
bo = bp->b_bufobj;
if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) {
td->td_pflags |= TDP_INBDFLUSH;
BO_BDFLUSH(bo, bp);
td->td_pflags &= ~TDP_INBDFLUSH;
} else
recursiveflushes++;
bdirty(bp);
/*
* Set B_CACHE, indicating that the buffer is fully valid. This is
* true even of NFS now.
*/
bp->b_flags |= B_CACHE;
/*
* This bmap keeps the system from needing to do the bmap later,
* perhaps when the system is attempting to do a sync. Since it
* is likely that the indirect block -- or whatever other datastructure
* that the filesystem needs is still in memory now, it is a good
* thing to do this. Note also, that if the pageout daemon is
* requesting a sync -- there might not be enough memory to do
* the bmap then... So, this is important to do.
*/
if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) {
VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL);
}
/*
* Set the *dirty* buffer range based upon the VM system dirty pages.
*/
vfs_setdirty(bp);
/*
* We need to do this here to satisfy the vnode_pager and the
* pageout daemon, so that it thinks that the pages have been
* "cleaned". Note that since the pages are in a delayed write
* buffer -- the VFS layer "will" see that the pages get written
* out on the next sync, or perhaps the cluster will be completed.
*/
vfs_clean_pages(bp);
bqrelse(bp);
/*
* Wakeup the buffer flushing daemon if we have a lot of dirty
* buffers (midpoint between our recovery point and our stall
* point).
*/
bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
/*
* note: we cannot initiate I/O from a bdwrite even if we wanted to,
* due to the softdep code.
*/
}
/*
* bdirty:
*
* Turn buffer into delayed write request. We must clear BIO_READ and
* B_RELBUF, and we must set B_DELWRI. We reassign the buffer to
* itself to properly update it in the dirty/clean lists. We mark it
* B_DONE to ensure that any asynchronization of the buffer properly
* clears B_DONE ( else a panic will occur later ).
*
* bdirty() is kinda like bdwrite() - we have to clear B_INVAL which
* might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty()
* should only be called if the buffer is known-good.
*
* Since the buffer is not on a queue, we do not update the numfreebuffers
* count.
*
* The buffer must be on QUEUE_NONE.
*/
void
bdirty(struct buf *bp)
{
CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
("bdirty: buffer %p still on queue %d", bp, bp->b_qindex));
BUF_ASSERT_HELD(bp);
bp->b_flags &= ~(B_RELBUF);
bp->b_iocmd = BIO_WRITE;
if ((bp->b_flags & B_DELWRI) == 0) {
bp->b_flags |= /* XXX B_DONE | */ B_DELWRI;
reassignbuf(bp);
atomic_add_int(&numdirtybuffers, 1);
bd_wakeup((lodirtybuffers + hidirtybuffers) / 2);
}
}
/*
* bundirty:
*
* Clear B_DELWRI for buffer.
*
* Since the buffer is not on a queue, we do not update the numfreebuffers
* count.
*
* The buffer must be on QUEUE_NONE.
*/
void
bundirty(struct buf *bp)
{
CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE,
("bundirty: buffer %p still on queue %d", bp, bp->b_qindex));
BUF_ASSERT_HELD(bp);
if (bp->b_flags & B_DELWRI) {
bp->b_flags &= ~B_DELWRI;
reassignbuf(bp);
atomic_subtract_int(&numdirtybuffers, 1);
numdirtywakeup(lodirtybuffers);
}
/*
* Since it is now being written, we can clear its deferred write flag.
*/
bp->b_flags &= ~B_DEFERRED;
}
/*
* bawrite:
*
* Asynchronous write. Start output on a buffer, but do not wait for
* it to complete. The buffer is released when the output completes.
*
* bwrite() ( or the VOP routine anyway ) is responsible for handling
* B_INVAL buffers. Not us.
*/
void
bawrite(struct buf *bp)
{
bp->b_flags |= B_ASYNC;
(void) bwrite(bp);
}
/*
* bwillwrite:
*
* Called prior to the locking of any vnodes when we are expecting to
* write. We do not want to starve the buffer cache with too many
* dirty buffers so we block here. By blocking prior to the locking
* of any vnodes we attempt to avoid the situation where a locked vnode
* prevents the various system daemons from flushing related buffers.
*/
void
bwillwrite(void)
{
if (numdirtybuffers >= hidirtybuffers) {
mtx_lock(&nblock);
while (numdirtybuffers >= hidirtybuffers) {
bd_wakeup(1);
needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH;
msleep(&needsbuffer, &nblock,
(PRIBIO + 4), "flswai", 0);
}
mtx_unlock(&nblock);
}
}
/*
* Return true if we have too many dirty buffers.
*/
int
buf_dirty_count_severe(void)
{
return(numdirtybuffers >= hidirtybuffers);
}
static __noinline int
buf_vm_page_count_severe(void)
{
KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1);
return vm_page_count_severe();
}
/*
* 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)
{
CTR3(KTR_BUF, "brelse(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
if (bp->b_flags & B_MANAGED) {
bqrelse(bp);
return;
}
if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
bp->b_error == EIO && !(bp->b_flags & B_INVAL)) {
/*
* Failed write, redirty. Must clear BIO_ERROR to prevent
* pages from being scrapped. If the error is anything
* other than an I/O error (EIO), assume that retrying
* is futile.
*/
bp->b_ioflags &= ~BIO_ERROR;
bdirty(bp);
} else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) ||
(bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) {
/*
* Either a failed I/O or we were asked to free or not
* cache the buffer.
*/
bp->b_flags |= B_INVAL;
if (!LIST_EMPTY(&bp->b_dep))
buf_deallocate(bp);
if (bp->b_flags & B_DELWRI) {
atomic_subtract_int(&numdirtybuffers, 1);
numdirtywakeup(lodirtybuffers);
}
bp->b_flags &= ~(B_DELWRI | B_CACHE);
if ((bp->b_flags & B_VMIO) == 0) {
if (bp->b_bufsize)
allocbuf(bp, 0);
if (bp->b_vp)
brelvp(bp);
}
}
/*
* We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release()
* is called with B_DELWRI set, the underlying pages may wind up
* getting freed causing a previous write (bdwrite()) to get 'lost'
* because pages associated with a B_DELWRI bp are marked clean.
*
* We still allow the B_INVAL case to call vfs_vmio_release(), even
* if B_DELWRI is set.
*
* If B_DELWRI is not set we may have to set B_RELBUF if we are low
* on pages to return pages to the VM page queues.
*/
if (bp->b_flags & B_DELWRI)
bp->b_flags &= ~B_RELBUF;
else if (buf_vm_page_count_severe()) {
/*
* The locking of the BO_LOCK is not necessary since
* BKGRDINPROG cannot be set while we hold the buf
* lock, it can only be cleared if it is already
* pending.
*/
if (bp->b_vp) {
if (!(bp->b_vflags & BV_BKGRDINPROG))
bp->b_flags |= B_RELBUF;
} else
bp->b_flags |= B_RELBUF;
}
/*
* VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
* constituted, not even NFS buffers now. Two flags effect this. If
* B_INVAL, the struct buf is invalidated but the VM object is kept
* around ( i.e. so it is trivial to reconstitute the buffer later ).
*
* If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be
* invalidated. BIO_ERROR cannot be set for a failed write unless the
* buffer is also B_INVAL because it hits the re-dirtying code above.
*
* Normally we can do this whether a buffer is B_DELWRI or not. If
* the buffer is an NFS buffer, it is tracking piecemeal writes or
* the commit state and we cannot afford to lose the buffer. If the
* buffer has a background write in progress, we need to keep it
* around to prevent it from being reconstituted and starting a second
* background write.
*/
if ((bp->b_flags & B_VMIO)
&& !(bp->b_vp->v_mount != NULL &&
(bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
!vn_isdisk(bp->b_vp, NULL) &&
(bp->b_flags & B_DELWRI))
) {
int i, j, resid;
vm_page_t m;
off_t foff;
vm_pindex_t poff;
vm_object_t obj;
obj = bp->b_bufobj->bo_object;
/*
* Get the base offset and length of the buffer. Note that
* in the VMIO case if the buffer block size is not
* page-aligned then b_data pointer may not be page-aligned.
* But our b_pages[] array *IS* page aligned.
*
* block sizes less then DEV_BSIZE (usually 512) are not
* supported due to the page granularity bits (m->valid,
* m->dirty, etc...).
*
* See man buf(9) for more information
*/
resid = bp->b_bufsize;
foff = bp->b_offset;
VM_OBJECT_LOCK(obj);
for (i = 0; i < bp->b_npages; i++) {
int had_bogus = 0;
m = bp->b_pages[i];
/*
* If we hit a bogus page, fixup *all* the bogus pages
* now.
*/
if (m == bogus_page) {
poff = OFF_TO_IDX(bp->b_offset);
had_bogus = 1;
for (j = i; j < bp->b_npages; j++) {
vm_page_t mtmp;
mtmp = bp->b_pages[j];
if (mtmp == bogus_page) {
mtmp = vm_page_lookup(obj, poff + j);
if (!mtmp) {
panic("brelse: page missing\n");
}
bp->b_pages[j] = mtmp;
}
}
if ((bp->b_flags & B_INVAL) == 0) {
pmap_qenter(
trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
m = bp->b_pages[i];
}
if ((bp->b_flags & B_NOCACHE) ||
(bp->b_ioflags & BIO_ERROR &&
bp->b_iocmd == BIO_READ)) {
int poffset = foff & PAGE_MASK;
int presid = resid > (PAGE_SIZE - poffset) ?
(PAGE_SIZE - poffset) : resid;
KASSERT(presid >= 0, ("brelse: extra page"));
vm_page_lock_queues();
vm_page_set_invalid(m, poffset, presid);
vm_page_unlock_queues();
if (had_bogus)
printf("avoided corruption bug in bogus_page/brelse code\n");
}
resid -= PAGE_SIZE - (foff & PAGE_MASK);
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
}
VM_OBJECT_UNLOCK(obj);
if (bp->b_flags & (B_INVAL | B_RELBUF))
vfs_vmio_release(bp);
} else if (bp->b_flags & B_VMIO) {
if (bp->b_flags & (B_INVAL | B_RELBUF)) {
vfs_vmio_release(bp);
}
} else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) {
if (bp->b_bufsize != 0)
allocbuf(bp, 0);
if (bp->b_vp != NULL)
brelvp(bp);
}
if (BUF_LOCKRECURSED(bp)) {
/* do not release to free list */
BUF_UNLOCK(bp);
return;
}
/* enqueue */
mtx_lock(&bqlock);
/* Handle delayed bremfree() processing. */
if (bp->b_flags & B_REMFREE)
bremfreel(bp);
if (bp->b_qindex != QUEUE_NONE)
panic("brelse: free buffer onto another queue???");
/*
* If the buffer has junk contents signal it and eventually
* clean up B_DELWRI and diassociate the vnode so that gbincore()
* doesn't find it.
*/
if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 ||
(bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0)
bp->b_flags |= B_INVAL;
if (bp->b_flags & B_INVAL) {
if (bp->b_flags & B_DELWRI)
bundirty(bp);
if (bp->b_vp)
brelvp(bp);
}
/* buffers with no memory */
if (bp->b_bufsize == 0) {
bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
if (bp->b_vflags & BV_BKGRDINPROG)
panic("losing buffer 1");
if (bp->b_kvasize) {
bp->b_qindex = QUEUE_EMPTYKVA;
} else {
bp->b_qindex = QUEUE_EMPTY;
}
TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
/* buffers with junk contents */
} else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) ||
(bp->b_ioflags & BIO_ERROR)) {
bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA);
if (bp->b_vflags & BV_BKGRDINPROG)
panic("losing buffer 2");
bp->b_qindex = QUEUE_CLEAN;
TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist);
/* remaining buffers */
} else {
if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) ==
(B_DELWRI|B_NEEDSGIANT))
bp->b_qindex = QUEUE_DIRTY_GIANT;
else if (bp->b_flags & B_DELWRI)
bp->b_qindex = QUEUE_DIRTY;
else
bp->b_qindex = QUEUE_CLEAN;
if (bp->b_flags & B_AGE)
TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist);
else
TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
}
mtx_unlock(&bqlock);
/*
* Fixup numfreebuffers count. The bp is on an appropriate queue
* unless locked. We then bump numfreebuffers if it is not B_DELWRI.
* We've already handled the B_INVAL case ( B_DELWRI will be clear
* if B_INVAL is set ).
*/
if (!(bp->b_flags & B_DELWRI))
bufcountwakeup();
/*
* Something we can maybe free or reuse
*/
if (bp->b_bufsize || bp->b_kvasize)
bufspacewakeup();
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT);
if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
panic("brelse: not dirty");
/* unlock */
BUF_UNLOCK(bp);
}
/*
* Release a buffer back to the appropriate queue but do not try to free
* it. The buffer is expected to be used again soon.
*
* bqrelse() is used by bdwrite() to requeue a delayed write, and used by
* biodone() to requeue an async I/O on completion. It is also used when
* known good buffers need to be requeued but we think we may need the data
* again soon.
*
* XXX we should be able to leave the B_RELBUF hint set on completion.
*/
void
bqrelse(struct buf *bp)
{
CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)),
("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp));
if (BUF_LOCKRECURSED(bp)) {
/* do not release to free list */
BUF_UNLOCK(bp);
return;
}
if (bp->b_flags & B_MANAGED) {
if (bp->b_flags & B_REMFREE) {
mtx_lock(&bqlock);
bremfreel(bp);
mtx_unlock(&bqlock);
}
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
BUF_UNLOCK(bp);
return;
}
mtx_lock(&bqlock);
/* Handle delayed bremfree() processing. */
if (bp->b_flags & B_REMFREE)
bremfreel(bp);
if (bp->b_qindex != QUEUE_NONE)
panic("bqrelse: free buffer onto another queue???");
/* buffers with stale but valid contents */
if (bp->b_flags & B_DELWRI) {
if (bp->b_flags & B_NEEDSGIANT)
bp->b_qindex = QUEUE_DIRTY_GIANT;
else
bp->b_qindex = QUEUE_DIRTY;
TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist);
} else {
/*
* The locking of the BO_LOCK for checking of the
* BV_BKGRDINPROG is not necessary since the
* BV_BKGRDINPROG cannot be set while we hold the buf
* lock, it can only be cleared if it is already
* pending.
*/
if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) {
bp->b_qindex = QUEUE_CLEAN;
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp,
b_freelist);
} else {
/*
* We are too low on memory, we have to try to free
* the buffer (most importantly: the wired pages
* making up its backing store) *now*.
*/
mtx_unlock(&bqlock);
brelse(bp);
return;
}
}
mtx_unlock(&bqlock);
if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
bufcountwakeup();
/*
* Something we can maybe free or reuse.
*/
if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
bufspacewakeup();
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY))
panic("bqrelse: not dirty");
/* unlock */
BUF_UNLOCK(bp);
}
/* Give pages used by the bp back to the VM system (where possible) */
static void
vfs_vmio_release(struct buf *bp)
{
int i;
vm_page_t m;
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
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_lock(m);
vm_page_lock_queues();
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->oflags & VPO_BUSY) == 0 && m->busy == 0 &&
m->wire_count == 0) {
/*
* Might as well free the page if we can and it has
* no valid data. We also free the page if the
* buffer was used for direct I/O
*/
if ((bp->b_flags & B_ASYNC) == 0 && !m->valid &&
m->hold_count == 0) {
vm_page_free(m);
} else if (bp->b_flags & B_DIRECT) {
vm_page_try_to_free(m);
} else if (buf_vm_page_count_severe()) {
vm_page_try_to_cache(m);
}
}
vm_page_unlock_queues();
vm_page_unlock(m);
}
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages);
if (bp->b_bufsize) {
bufspacewakeup();
bp->b_bufsize = 0;
}
bp->b_npages = 0;
bp->b_flags &= ~B_VMIO;
if (bp->b_vp)
brelvp(bp);
}
/*
* Check to see if a block at a particular lbn is available for a clustered
* write.
*/
static int
vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno)
{
struct buf *bpa;
int match;
match = 0;
/* If the buf isn't in core skip it */
if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL)
return (0);
/* If the buf is busy we don't want to wait for it */
if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
return (0);
/* Only cluster with valid clusterable delayed write buffers */
if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) !=
(B_DELWRI | B_CLUSTEROK))
goto done;
if (bpa->b_bufsize != size)
goto done;
/*
* Check to see if it is in the expected place on disk and that the
* block has been mapped.
*/
if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno))
match = 1;
done:
BUF_UNLOCK(bpa);
return (match);
}
/*
* vfs_bio_awrite:
*
* Implement clustered async writes for clearing out B_DELWRI buffers.
* This is much better then the old way of writing only one buffer at
* a time. Note that we may not be presented with the buffers in the
* correct order, so we search for the cluster in both directions.
*/
int
vfs_bio_awrite(struct buf *bp)
{
struct bufobj *bo;
int i;
int j;
daddr_t lblkno = bp->b_lblkno;
struct vnode *vp = bp->b_vp;
int ncl;
int nwritten;
int size;
int maxcl;
bo = &vp->v_bufobj;
/*
* right now we support clustered writing only to regular files. If
* we find a clusterable block we could be in the middle of a cluster
* rather then at the beginning.
*/
if ((vp->v_type == VREG) &&
(vp->v_mount != 0) && /* Only on nodes that have the size info */
(bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) {
size = vp->v_mount->mnt_stat.f_iosize;
maxcl = MAXPHYS / size;
BO_LOCK(bo);
for (i = 1; i < maxcl; i++)
if (vfs_bio_clcheck(vp, size, lblkno + i,
bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0)
break;
for (j = 1; i + j <= maxcl && j <= lblkno; j++)
if (vfs_bio_clcheck(vp, size, lblkno - j,
bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0)
break;
BO_UNLOCK(bo);
--j;
ncl = i + j;
/*
* this is a possible cluster write
*/
if (ncl != 1) {
BUF_UNLOCK(bp);
nwritten = cluster_wbuild(vp, size, lblkno - j, ncl);
return nwritten;
}
}
bremfree(bp);
bp->b_flags |= B_ASYNC;
/*
* default (old) behavior, writing out only one block
*
* XXX returns b_bufsize instead of b_bcount for nwritten?
*/
nwritten = bp->b_bufsize;
(void) bwrite(bp);
return nwritten;
}
/*
* getnewbuf:
*
* Find and initialize a new buffer header, freeing up existing buffers
* in the bufqueues as necessary. The new buffer is returned locked.
*
* Important: B_INVAL is not set. If the caller wishes to throw the
* buffer away, the caller must set B_INVAL prior to calling brelse().
*
* We block if:
* We have insufficient buffer headers
* We have insufficient buffer space
* buffer_map is too fragmented ( space reservation fails )
* If we have to flush dirty buffers ( but we try to avoid this )
*
* To avoid VFS layer recursion we do not flush dirty buffers ourselves.
* Instead we ask the buf daemon to do it for us. We attempt to
* avoid piecemeal wakeups of the pageout daemon.
*/
static struct buf *
getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
int gbflags)
{
struct thread *td;
struct buf *bp;
struct buf *nbp;
int defrag = 0;
int nqindex;
static int flushingbufs;
td = curthread;
/*
* We can't afford to block since we might be holding a vnode lock,
* which may prevent system daemons from running. We deal with
* low-memory situations by proactively returning memory and running
* async I/O rather then sync I/O.
*/
atomic_add_int(&getnewbufcalls, 1);
atomic_subtract_int(&getnewbufrestarts, 1);
restart:
atomic_add_int(&getnewbufrestarts, 1);
/*
* Setup for scan. If we do not have enough free buffers,
* we setup a degenerate case that immediately fails. Note
* that if we are specially marked process, we are allowed to
* dip into our reserves.
*
* The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN
*
* We start with EMPTYKVA. If the list is empty we backup to EMPTY.
* However, there are a number of cases (defragging, reusing, ...)
* where we cannot backup.
*/
mtx_lock(&bqlock);
nqindex = QUEUE_EMPTYKVA;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
if (nbp == NULL) {
/*
* If no EMPTYKVA buffers and we are either
* defragging or reusing, locate a CLEAN buffer
* to free or reuse. If bufspace useage is low
* skip this step so we can allocate a new buffer.
*/
if (defrag || bufspace >= lobufspace) {
nqindex = QUEUE_CLEAN;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
}
/*
* If we could not find or were not allowed to reuse a
* CLEAN buffer, check to see if it is ok to use an EMPTY
* buffer. We can only use an EMPTY buffer if allocating
* its KVA would not otherwise run us out of buffer space.
*/
if (nbp == NULL && defrag == 0 &&
bufspace + maxsize < hibufspace) {
nqindex = QUEUE_EMPTY;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
}
}
/*
* Run scan, possibly freeing data and/or kva mappings on the fly
* depending.
*/
while ((bp = nbp) != NULL) {
int qindex = nqindex;
/*
* Calculate next bp ( we can only use it if we do not block
* or do other fancy things ).
*/
if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) {
switch(qindex) {
case QUEUE_EMPTY:
nqindex = QUEUE_EMPTYKVA;
if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA])))
break;
/* FALLTHROUGH */
case QUEUE_EMPTYKVA:
nqindex = QUEUE_CLEAN;
if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN])))
break;
/* FALLTHROUGH */
case QUEUE_CLEAN:
/*
* nbp is NULL.
*/
break;
}
}
/*
* If we are defragging then we need a buffer with
* b_kvasize != 0. XXX this situation should no longer
* occur, if defrag is non-zero the buffer's b_kvasize
* should also be non-zero at this point. XXX
*/
if (defrag && bp->b_kvasize == 0) {
printf("Warning: defrag empty buffer %p\n", bp);
continue;
}
/*
* Start freeing the bp. This is somewhat involved. nbp
* remains valid only for QUEUE_EMPTY[KVA] bp's.
*/
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
continue;
if (bp->b_vp) {
BO_LOCK(bp->b_bufobj);
if (bp->b_vflags & BV_BKGRDINPROG) {
BO_UNLOCK(bp->b_bufobj);
BUF_UNLOCK(bp);
continue;
}
BO_UNLOCK(bp->b_bufobj);
}
CTR6(KTR_BUF,
"getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d "
"queue %d (recycling)", bp, bp->b_vp, bp->b_flags,
bp->b_kvasize, bp->b_bufsize, qindex);
/*
* Sanity Checks
*/
KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp));
/*
* Note: we no longer distinguish between VMIO and non-VMIO
* buffers.
*/
KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex));
bremfreel(bp);
mtx_unlock(&bqlock);
if (qindex == QUEUE_CLEAN) {
if (bp->b_flags & B_VMIO) {
bp->b_flags &= ~B_ASYNC;
vfs_vmio_release(bp);
}
if (bp->b_vp)
brelvp(bp);
}
/*
* NOTE: nbp is now entirely invalid. We can only restart
* the scan from this point on.
*
* Get the rest of the buffer freed up. b_kva* is still
* valid after this operation.
*/
if (bp->b_rcred != NOCRED) {
crfree(bp->b_rcred);
bp->b_rcred = NOCRED;
}
if (bp->b_wcred != NOCRED) {
crfree(bp->b_wcred);
bp->b_wcred = NOCRED;
}
if (!LIST_EMPTY(&bp->b_dep))
buf_deallocate(bp);
if (bp->b_vflags & BV_BKGRDINPROG)
panic("losing buffer 3");
KASSERT(bp->b_vp == NULL,
("bp: %p still has vnode %p. qindex: %d",
bp, bp->b_vp, qindex));
KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
("bp: %p still on a buffer list. xflags %X",
bp, bp->b_xflags));
if (bp->b_bufsize)
allocbuf(bp, 0);
bp->b_flags = 0;
bp->b_ioflags = 0;
bp->b_xflags = 0;
bp->b_vflags = 0;
bp->b_vp = NULL;
bp->b_blkno = bp->b_lblkno = 0;
bp->b_offset = NOOFFSET;
bp->b_iodone = 0;
bp->b_error = 0;
bp->b_resid = 0;
bp->b_bcount = 0;
bp->b_npages = 0;
bp->b_dirtyoff = bp->b_dirtyend = 0;
bp->b_bufobj = NULL;
bp->b_pin_count = 0;
bp->b_fsprivate1 = NULL;
bp->b_fsprivate2 = NULL;
bp->b_fsprivate3 = NULL;
LIST_INIT(&bp->b_dep);
/*
* If we are defragging then free the buffer.
*/
if (defrag) {
bp->b_flags |= B_INVAL;
bfreekva(bp);
brelse(bp);
defrag = 0;
goto restart;
}
/*
* Notify any waiters for the buffer lock about
* identity change by freeing the buffer.
*/
if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) {
bp->b_flags |= B_INVAL;
bfreekva(bp);
brelse(bp);
goto restart;
}
/*
* If we are overcomitted then recover the buffer and its
* KVM space. This occurs in rare situations when multiple
* processes are blocked in getnewbuf() or allocbuf().
*/
if (bufspace >= hibufspace)
flushingbufs = 1;
if (flushingbufs && bp->b_kvasize != 0) {
bp->b_flags |= B_INVAL;
bfreekva(bp);
brelse(bp);
goto restart;
}
if (bufspace < lobufspace)
flushingbufs = 0;
break;
}
/*
* If we exhausted our list, sleep as appropriate. We may have to
* wakeup various daemons and write out some dirty buffers.
*
* Generally we are sleeping due to insufficient buffer space.
*/
if (bp == NULL) {
int flags, norunbuf;
char *waitmsg;
int fl;
if (defrag) {
flags = VFS_BIO_NEED_BUFSPACE;
waitmsg = "nbufkv";
} else if (bufspace >= hibufspace) {
waitmsg = "nbufbs";
flags = VFS_BIO_NEED_BUFSPACE;
} else {
waitmsg = "newbuf";
flags = VFS_BIO_NEED_ANY;
}
mtx_lock(&nblock);
needsbuffer |= flags;
mtx_unlock(&nblock);
mtx_unlock(&bqlock);
bd_speedup(); /* heeeelp */
if (gbflags & GB_NOWAIT_BD)
return (NULL);
mtx_lock(&nblock);
while (needsbuffer & flags) {
if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) {
mtx_unlock(&nblock);
/*
* getblk() is called with a vnode
* locked, and some majority of the
* dirty buffers may as well belong to
* the vnode. Flushing the buffers
* there would make a progress that
* cannot be achieved by the
* buf_daemon, that cannot lock the
* vnode.
*/
norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
(td->td_pflags & TDP_NORUNNINGBUF);
/* play bufdaemon */
td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
fl = buf_do_flush(vp);
td->td_pflags &= norunbuf;
mtx_lock(&nblock);
if (fl != 0)
continue;
if ((needsbuffer & flags) == 0)
break;
}
if (msleep(&needsbuffer, &nblock,
(PRIBIO + 4) | slpflag, waitmsg, slptimeo)) {
mtx_unlock(&nblock);
return (NULL);
}
}
mtx_unlock(&nblock);
} else {
/*
* We finally have a valid bp. We aren't quite out of the
* woods, we still have to reserve kva space. In order
* to keep fragmentation sane we only allocate kva in
* BKVASIZE chunks.
*/
maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
if (maxsize != bp->b_kvasize) {
vm_offset_t addr = 0;
bfreekva(bp);
vm_map_lock(buffer_map);
if (vm_map_findspace(buffer_map,
vm_map_min(buffer_map), maxsize, &addr)) {
/*
* Uh oh. Buffer map is to fragmented. We
* must defragment the map.
*/
atomic_add_int(&bufdefragcnt, 1);
vm_map_unlock(buffer_map);
defrag = 1;
bp->b_flags |= B_INVAL;
brelse(bp);
goto restart;
}
if (addr) {
vm_map_insert(buffer_map, NULL, 0,
addr, addr + maxsize,
VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
bp->b_kvabase = (caddr_t) addr;
bp->b_kvasize = maxsize;
atomic_add_long(&bufspace, bp->b_kvasize);
atomic_add_int(&bufreusecnt, 1);
}
vm_map_unlock(buffer_map);
}
bp->b_saveaddr = bp->b_kvabase;
bp->b_data = bp->b_saveaddr;
}
return(bp);
}
/*
* buf_daemon:
*
* buffer flushing daemon. Buffers are normally flushed by the
* update daemon but if it cannot keep up this process starts to
* take the load in an attempt to prevent getnewbuf() from blocking.
*/
static struct kproc_desc buf_kp = {
"bufdaemon",
buf_daemon,
&bufdaemonproc
};
SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp);
static int
buf_do_flush(struct vnode *vp)
{
int flushed;
flushed = flushbufqueues(vp, QUEUE_DIRTY, 0);
/* The list empty check here is slightly racy */
if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) {
mtx_lock(&Giant);
flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0);
mtx_unlock(&Giant);
}
if (flushed == 0) {
/*
* Could not find any buffers without rollback
* dependencies, so just write the first one
* in the hopes of eventually making progress.
*/
flushbufqueues(vp, QUEUE_DIRTY, 1);
if (!TAILQ_EMPTY(
&bufqueues[QUEUE_DIRTY_GIANT])) {
mtx_lock(&Giant);
flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1);
mtx_unlock(&Giant);
}
}
return (flushed);
}
static void
buf_daemon()
{
int lodirtysave;
/*
* This process needs to be suspended prior to shutdown sync.
*/
EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc,
SHUTDOWN_PRI_LAST);
/*
* This process is allowed to take the buffer cache to the limit
*/
curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED;
mtx_lock(&bdlock);
for (;;) {
bd_request = 0;
mtx_unlock(&bdlock);
kproc_suspend_check(bufdaemonproc);
lodirtysave = lodirtybuffers;
if (bd_speedupreq) {
lodirtybuffers = numdirtybuffers / 2;
bd_speedupreq = 0;
}
/*
* Do the flush. Limit the amount of in-transit I/O we
* allow to build up, otherwise we would completely saturate
* the I/O system. Wakeup any waiting processes before we
* normally would so they can run in parallel with our drain.
*/
while (numdirtybuffers > lodirtybuffers) {
if (buf_do_flush(NULL) == 0)
break;
uio_yield();
}
lodirtybuffers = lodirtysave;
/*
* Only clear bd_request if we have reached our low water
* mark. The buf_daemon normally waits 1 second and
* then incrementally flushes any dirty buffers that have
* built up, within reason.
*
* If we were unable to hit our low water mark and couldn't
* find any flushable buffers, we sleep half a second.
* Otherwise we loop immediately.
*/
mtx_lock(&bdlock);
if (numdirtybuffers <= lodirtybuffers) {
/*
* We reached our low water mark, reset the
* request and sleep until we are needed again.
* The sleep is just so the suspend code works.
*/
bd_request = 0;
msleep(&bd_request, &bdlock, PVM, "psleep", hz);
} else {
/*
* We couldn't find any flushable dirty buffers but
* still have too many dirty buffers, we
* have to sleep and try again. (rare)
*/
msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10);
}
}
}
/*
* flushbufqueues:
*
* Try to flush a buffer in the dirty queue. We must be careful to
* free up B_INVAL buffers instead of write them, which NFS is
* particularly sensitive to.
*/
static int flushwithdeps = 0;
SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps,
0, "Number of buffers flushed with dependecies that require rollbacks");
static int
flushbufqueues(struct vnode *lvp, int queue, int flushdeps)
{
struct buf *sentinel;
struct vnode *vp;
struct mount *mp;
struct buf *bp;
int hasdeps;
int flushed;
int target;
if (lvp == NULL) {
target = numdirtybuffers - lodirtybuffers;
if (flushdeps && target > 2)
target /= 2;
} else
target = flushbufqtarget;
flushed = 0;
bp = NULL;
sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
sentinel->b_qindex = QUEUE_SENTINEL;
mtx_lock(&bqlock);
TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
while (flushed != target) {
bp = TAILQ_NEXT(sentinel, b_freelist);
if (bp != NULL) {
TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel,
b_freelist);
} else
break;
/*
* Skip sentinels inserted by other invocations of the
* flushbufqueues(), taking care to not reorder them.
*/
if (bp->b_qindex == QUEUE_SENTINEL)
continue;
/*
* Only flush the buffers that belong to the
* vnode locked by the curthread.
*/
if (lvp != NULL && bp->b_vp != lvp)
continue;
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
continue;
if (bp->b_pin_count > 0) {
BUF_UNLOCK(bp);
continue;
}
BO_LOCK(bp->b_bufobj);
if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
(bp->b_flags & B_DELWRI) == 0) {
BO_UNLOCK(bp->b_bufobj);
BUF_UNLOCK(bp);
continue;
}
BO_UNLOCK(bp->b_bufobj);
if (bp->b_flags & B_INVAL) {
bremfreel(bp);
mtx_unlock(&bqlock);
brelse(bp);
flushed++;
numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
mtx_lock(&bqlock);
continue;
}
if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) {
if (flushdeps == 0) {
BUF_UNLOCK(bp);
continue;
}
hasdeps = 1;
} else
hasdeps = 0;
/*
* We must hold the lock on a vnode before writing
* one of its buffers. Otherwise we may confuse, or
* in the case of a snapshot vnode, deadlock the
* system.
*
* The lock order here is the reverse of the normal
* of vnode followed by buf lock. This is ok because
* the NOWAIT will prevent deadlock.
*/
vp = bp->b_vp;
if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
BUF_UNLOCK(bp);
continue;
}
if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) {
mtx_unlock(&bqlock);
CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
if (curproc == bufdaemonproc)
vfs_bio_awrite(bp);
else {
bremfree(bp);
bwrite(bp);
notbufdflashes++;
}
vn_finished_write(mp);
VOP_UNLOCK(vp, 0);
flushwithdeps += hasdeps;
flushed++;
/*
* Sleeping on runningbufspace while holding
* vnode lock leads to deadlock.
*/
if (curproc == bufdaemonproc)
waitrunningbufspace();
numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2);
mtx_lock(&bqlock);
continue;
}
vn_finished_write(mp);
BUF_UNLOCK(bp);
}
TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
mtx_unlock(&bqlock);
free(sentinel, M_TEMP);
return (flushed);
}
/*
* Check to see if a block is currently memory resident.
*/
struct buf *
incore(struct bufobj *bo, daddr_t blkno)
{
struct buf *bp;
BO_LOCK(bo);
bp = gbincore(bo, blkno);
BO_UNLOCK(bo);
return (bp);
}
/*
* Returns true if no I/O is needed to access the
* associated VM object. This is like incore except
* it also hunts around in the VM system for the data.
*/
static int
inmem(struct vnode * vp, daddr_t blkno)
{
vm_object_t obj;
vm_offset_t toff, tinc, size;
vm_page_t m;
vm_ooffset_t off;
ASSERT_VOP_LOCKED(vp, "inmem");
if (incore(&vp->v_bufobj, blkno))
return 1;
if (vp->v_mount == NULL)
return 0;
obj = vp->v_object;
if (obj == NULL)
return (0);
size = PAGE_SIZE;
if (size > vp->v_mount->mnt_stat.f_iosize)
size = vp->v_mount->mnt_stat.f_iosize;
off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize;
VM_OBJECT_LOCK(obj);
for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) {
m = vm_page_lookup(obj, OFF_TO_IDX(off + toff));
if (!m)
goto notinmem;
tinc = size;
if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK))
tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK);
if (vm_page_is_valid(m,
(vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0)
goto notinmem;
}
VM_OBJECT_UNLOCK(obj);
return 1;
notinmem:
VM_OBJECT_UNLOCK(obj);
return (0);
}
/*
* vfs_setdirty:
*
* Sets the dirty range for a buffer based on the status of the dirty
* bits in the pages comprising the buffer.
*
* The range is limited to the size of the buffer.
*
* This routine is primarily used by NFS, but is generalized for the
* B_VMIO case.
*/
static void
vfs_setdirty(struct buf *bp)
{
/*
* Degenerate case - empty buffer
*/
if (bp->b_bufsize == 0)
return;
if ((bp->b_flags & B_VMIO) == 0)
return;
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
vfs_setdirty_locked_object(bp);
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
}
static void
vfs_setdirty_locked_object(struct buf *bp)
{
vm_object_t object;
int i;
object = bp->b_bufobj->bo_object;
VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
/*
* We qualify the scan for modified pages on whether the
* object has been flushed yet.
*/
if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) {
vm_offset_t boffset;
vm_offset_t eoffset;
vm_page_lock_queues();
/*
* test the pages to see if they have been modified directly
* by users through the VM system.
*/
for (i = 0; i < bp->b_npages; i++)
vm_page_test_dirty(bp->b_pages[i]);
/*
* Calculate the encompassing dirty range, boffset and eoffset,
* (eoffset - boffset) bytes.
*/
for (i = 0; i < bp->b_npages; i++) {
if (bp->b_pages[i]->dirty)
break;
}
boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
for (i = bp->b_npages - 1; i >= 0; --i) {
if (bp->b_pages[i]->dirty) {
break;
}
}
eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
vm_page_unlock_queues();
/*
* Fit it to the buffer.
*/
if (eoffset > bp->b_bcount)
eoffset = bp->b_bcount;
/*
* If we have a good dirty range, merge with the existing
* dirty range.
*/
if (boffset < eoffset) {
if (bp->b_dirtyoff > boffset)
bp->b_dirtyoff = boffset;
if (bp->b_dirtyend < eoffset)
bp->b_dirtyend = eoffset;
}
}
}
/*
* getblk:
*
* Get a block given a specified block and offset into a file/device.
* The buffers B_DONE bit will be cleared on return, making it almost
* ready for an I/O initiation. B_INVAL may or may not be set on
* return. The caller should clear B_INVAL prior to initiating a
* READ.
*
* For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for
* an existing buffer.
*
* For a VMIO buffer, B_CACHE is modified according to the backing VM.
* If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set
* and then cleared based on the backing VM. If the previous buffer is
* non-0-sized but invalid, B_CACHE will be cleared.
*
* If getblk() must create a new buffer, the new buffer is returned with
* both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which
* case it is returned with B_INVAL clear and B_CACHE set based on the
* backing VM.
*
* getblk() also forces a bwrite() for any B_DELWRI buffer whos
* B_CACHE bit is clear.
*
* What this means, basically, is that the caller should use B_CACHE to
* determine whether the buffer is fully valid or not and should clear
* B_INVAL prior to issuing a read. If the caller intends to validate
* the buffer by loading its data area with something, the caller needs
* to clear B_INVAL. If the caller does this without issuing an I/O,
* the caller should set B_CACHE ( as an optimization ), else the caller
* should issue the I/O and biodone() will set B_CACHE if the I/O was
* a write attempt or if it was a successfull read. If the caller
* intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR
* prior to issuing the READ. biodone() will *not* clear B_INVAL.
*/
struct buf *
getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo,
int flags)
{
struct buf *bp;
struct bufobj *bo;
int error;
CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
ASSERT_VOP_LOCKED(vp, "getblk");
if (size > MAXBSIZE)
panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
bo = &vp->v_bufobj;
loop:
/*
* Block if we are low on buffers. Certain processes are allowed
* to completely exhaust the buffer cache.
*
* If this check ever becomes a bottleneck it may be better to
* move it into the else, when gbincore() fails. At the moment
* it isn't a problem.
*
* XXX remove if 0 sections (clean this up after its proven)
*/
if (numfreebuffers == 0) {
if (TD_IS_IDLETHREAD(curthread))
return NULL;
mtx_lock(&nblock);
needsbuffer |= VFS_BIO_NEED_ANY;
mtx_unlock(&nblock);
}
BO_LOCK(bo);
bp = gbincore(bo, blkno);
if (bp != NULL) {
int lockflags;
/*
* Buffer is in-core. If the buffer is not busy, it must
* be on a queue.
*/
lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK;
if (flags & GB_LOCK_NOWAIT)
lockflags |= LK_NOWAIT;
error = BUF_TIMELOCK(bp, lockflags,
BO_MTX(bo), "getblk", slpflag, slptimeo);
/*
* If we slept and got the lock we have to restart in case
* the buffer changed identities.
*/
if (error == ENOLCK)
goto loop;
/* We timed out or were interrupted. */
else if (error)
return (NULL);
/*
* The buffer is locked. B_CACHE is cleared if the buffer is
* invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set
* and for a VMIO buffer B_CACHE is adjusted according to the
* backing VM cache.
*/
if (bp->b_flags & B_INVAL)
bp->b_flags &= ~B_CACHE;
else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0)
bp->b_flags |= B_CACHE;
bremfree(bp);
/*
* check for size inconsistancies for non-VMIO case.
*/
if (bp->b_bcount != size) {
if ((bp->b_flags & B_VMIO) == 0 ||
(size > bp->b_kvasize)) {
if (bp->b_flags & B_DELWRI) {
/*
* If buffer is pinned and caller does
* not want sleep waiting for it to be
* unpinned, bail out
* */
if (bp->b_pin_count > 0) {
if (flags & GB_LOCK_NOWAIT) {
bqrelse(bp);
return (NULL);
} else {
bunpin_wait(bp);
}
}
bp->b_flags |= B_NOCACHE;
bwrite(bp);
} else {
if (LIST_EMPTY(&bp->b_dep)) {
bp->b_flags |= B_RELBUF;
brelse(bp);
} else {
bp->b_flags |= B_NOCACHE;
bwrite(bp);
}
}
goto loop;
}
}
/*
* If the size is inconsistant in the VMIO case, we can resize
* the buffer. This might lead to B_CACHE getting set or
* cleared. If the size has not changed, B_CACHE remains
* unchanged from its previous state.
*/
if (bp->b_bcount != size)
allocbuf(bp, size);
KASSERT(bp->b_offset != NOOFFSET,
("getblk: no buffer offset"));
/*
* A buffer with B_DELWRI set and B_CACHE clear must
* be committed before we can return the buffer in
* order to prevent the caller from issuing a read
* ( due to B_CACHE not being set ) and overwriting
* it.
*
* Most callers, including NFS and FFS, need this to
* operate properly either because they assume they
* can issue a read if B_CACHE is not set, or because
* ( for example ) an uncached B_DELWRI might loop due
* to softupdates re-dirtying the buffer. In the latter
* case, B_CACHE is set after the first write completes,
* preventing further loops.
* NOTE! b*write() sets B_CACHE. If we cleared B_CACHE
* above while extending the buffer, we cannot allow the
* buffer to remain with B_CACHE set after the write
* completes or it will represent a corrupt state. To
* deal with this we set B_NOCACHE to scrap the buffer
* after the write.
*
* We might be able to do something fancy, like setting
* B_CACHE in bwrite() except if B_DELWRI is already set,
* so the below call doesn't set B_CACHE, but that gets real
* confusing. This is much easier.
*/
if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) {
bp->b_flags |= B_NOCACHE;
bwrite(bp);
goto loop;
}
bp->b_flags &= ~B_DONE;
} else {
int bsize, maxsize, vmio;
off_t offset;
/*
* Buffer is not in-core, create new buffer. The buffer
* returned by getnewbuf() is locked. Note that the returned
* buffer is also considered valid (not marked B_INVAL).
*/
BO_UNLOCK(bo);
/*
* If the user does not want us to create the buffer, bail out
* here.
*/
if (flags & GB_NOCREAT)
return NULL;
bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
offset = blkno * bsize;
vmio = vp->v_object != NULL;
maxsize = vmio ? size + (offset & PAGE_MASK) : size;
maxsize = imax(maxsize, bsize);
bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags);
if (bp == NULL) {
if (slpflag || slptimeo)
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.
*
* Note: this must occur before we associate the buffer
* with the vp especially considering limitations in
* the splay tree implementation when dealing with duplicate
* lblkno's.
*/
BO_LOCK(bo);
if (gbincore(bo, blkno)) {
BO_UNLOCK(bo);
bp->b_flags |= B_INVAL;
brelse(bp);
goto loop;
}
/*
* Insert the buffer into the hash, so that it can
* be found by incore.
*/
bp->b_blkno = bp->b_lblkno = blkno;
bp->b_offset = offset;
bgetvp(vp, bp);
BO_UNLOCK(bo);
/*
* set B_VMIO bit. allocbuf() the buffer bigger. Since the
* buffer size starts out as 0, B_CACHE will be set by
* allocbuf() for the VMIO case prior to it testing the
* backing store for validity.
*/
if (vmio) {
bp->b_flags |= B_VMIO;
#if defined(VFS_BIO_DEBUG)
if (vn_canvmio(vp) != TRUE)
printf("getblk: VMIO on vnode type %d\n",
vp->v_type);
#endif
KASSERT(vp->v_object == bp->b_bufobj->bo_object,
("ARGH! different b_bufobj->bo_object %p %p %p\n",
bp, vp->v_object, bp->b_bufobj->bo_object));
} else {
bp->b_flags &= ~B_VMIO;
KASSERT(bp->b_bufobj->bo_object == NULL,
("ARGH! has b_bufobj->bo_object %p %p\n",
bp, bp->b_bufobj->bo_object));
}
allocbuf(bp, size);
bp->b_flags &= ~B_DONE;
}
CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp);
BUF_ASSERT_HELD(bp);
KASSERT(bp->b_bufobj == bo,
("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
return (bp);
}
/*
* Get an empty, disassociated buffer of given size. The buffer is initially
* set to B_INVAL.
*/
struct buf *
geteblk(int size, int flags)
{
struct buf *bp;
int maxsize;
maxsize = (size + BKVAMASK) & ~BKVAMASK;
while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) {
if ((flags & GB_NOWAIT_BD) &&
(curthread->td_pflags & TDP_BUFNEED) != 0)
return (NULL);
}
allocbuf(bp, size);
bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
BUF_ASSERT_HELD(bp);
return (bp);
}
/*
* This code constitutes the buffer memory from either anonymous system
* memory (in the case of non-VMIO operations) or from an associated
* VM object (in the case of VMIO operations). This code is able to
* resize a buffer up or down.
*
* Note that this code is tricky, and has many complications to resolve
* deadlock or inconsistant data situations. Tread lightly!!!
* There are B_CACHE and B_DELWRI interactions that must be dealt with by
* the caller. Calling this code willy nilly can result in the loss of data.
*
* allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with
* B_CACHE for the non-VMIO case.
*/
int
allocbuf(struct buf *bp, int size)
{
int newbsize, mbsize;
int i;
BUF_ASSERT_HELD(bp);
if (bp->b_kvasize < size)
panic("allocbuf: buffer too small");
if ((bp->b_flags & B_VMIO) == 0) {
caddr_t origbuf;
int origbufsize;
/*
* Just get anonymous memory from the kernel. Don't
* mess with B_CACHE.
*/
mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
if (bp->b_flags & B_MALLOC)
newbsize = mbsize;
else
newbsize = round_page(size);
if (newbsize < bp->b_bufsize) {
/*
* malloced buffers are not shrunk
*/
if (bp->b_flags & B_MALLOC) {
if (newbsize) {
bp->b_bcount = size;
} else {
free(bp->b_data, M_BIOBUF);
if (bp->b_bufsize) {
atomic_subtract_long(
&bufmallocspace,
bp->b_bufsize);
bufspacewakeup();
bp->b_bufsize = 0;
}
bp->b_saveaddr = bp->b_kvabase;
bp->b_data = bp->b_saveaddr;
bp->b_bcount = 0;
bp->b_flags &= ~B_MALLOC;
}
return 1;
}
vm_hold_free_pages(
bp,
(vm_offset_t) bp->b_data + newbsize,
(vm_offset_t) bp->b_data + bp->b_bufsize);
} else if (newbsize > bp->b_bufsize) {
/*
* We only use malloced memory on the first allocation.
* and revert to page-allocated memory when the buffer
* grows.
*/
/*
* There is a potential smp race here that could lead
* to bufmallocspace slightly passing the max. It
* is probably extremely rare and not worth worrying
* over.
*/
if ( (bufmallocspace < maxbufmallocspace) &&
(bp->b_bufsize == 0) &&
(mbsize <= PAGE_SIZE/2)) {
bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK);
bp->b_bufsize = mbsize;
bp->b_bcount = size;
bp->b_flags |= B_MALLOC;
atomic_add_long(&bufmallocspace, mbsize);
return 1;
}
origbuf = NULL;
origbufsize = 0;
/*
* If the buffer is growing on its other-than-first allocation,
* then we revert to the page-allocation scheme.
*/
if (bp->b_flags & B_MALLOC) {
origbuf = bp->b_data;
origbufsize = bp->b_bufsize;
bp->b_data = bp->b_kvabase;
if (bp->b_bufsize) {
atomic_subtract_long(&bufmallocspace,
bp->b_bufsize);
bufspacewakeup();
bp->b_bufsize = 0;
}
bp->b_flags &= ~B_MALLOC;
newbsize = round_page(newbsize);
}
vm_hold_load_pages(
bp,
(vm_offset_t) bp->b_data + bp->b_bufsize,
(vm_offset_t) bp->b_data + newbsize);
if (origbuf) {
bcopy(origbuf, bp->b_data, origbufsize);
free(origbuf, M_BIOBUF);
}
}
} else {
int desiredpages;
newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
desiredpages = (size == 0) ? 0 :
num_pages((bp->b_offset & PAGE_MASK) + newbsize);
if (bp->b_flags & B_MALLOC)
panic("allocbuf: VMIO buffer can't be malloced");
/*
* Set B_CACHE initially if buffer is 0 length or will become
* 0-length.
*/
if (size == 0 || bp->b_bufsize == 0)
bp->b_flags |= B_CACHE;
if (newbsize < bp->b_bufsize) {
/*
* DEV_BSIZE aligned new buffer size is less then the
* DEV_BSIZE aligned existing buffer size. Figure out
* if we have to remove any pages.
*/
if (desiredpages < bp->b_npages) {
vm_page_t m;
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
for (i = desiredpages; i < bp->b_npages; i++) {
/*
* the page is not freed here -- it
* is the responsibility of
* vnode_pager_setsize
*/
m = bp->b_pages[i];
KASSERT(m != bogus_page,
("allocbuf: bogus page found"));
while (vm_page_sleep_if_busy(m, TRUE,
"biodep"))
continue;
bp->b_pages[i] = NULL;
vm_page_lock(m);
vm_page_lock_queues();
vm_page_unwire(m, 0);
vm_page_unlock_queues();
vm_page_unlock(m);
}
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) +
(desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages));
bp->b_npages = desiredpages;
}
} else if (size > bp->b_bcount) {
/*
* We are growing the buffer, possibly in a
* byte-granular fashion.
*/
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.
*/
obj = bp->b_bufobj->bo_object;
VM_OBJECT_LOCK(obj);
while (bp->b_npages < desiredpages) {
vm_page_t m;
vm_pindex_t pi;
pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages;
if ((m = vm_page_lookup(obj, pi)) == NULL) {
/*
* note: must allocate system pages
* since blocking here could intefere
* with paging I/O, no matter which
* process we are.
*/
m = vm_page_alloc(obj, pi,
VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
VM_ALLOC_WIRED);
if (m == NULL) {
atomic_add_int(&vm_pageout_deficit,
desiredpages - bp->b_npages);
VM_OBJECT_UNLOCK(obj);
VM_WAIT;
VM_OBJECT_LOCK(obj);
} else {
if (m->valid == 0)
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 VPO_BUSY here. Blocking on
* m->busy might lead to a deadlock:
*
* vm_fault->getpages->cluster_read->allocbuf
*
*/
if ((m->oflags & VPO_BUSY) != 0) {
/*
* Reference the page before unlocking
* and sleeping so that the page daemon
* is less likely to reclaim it.
*/
vm_page_lock_queues();
vm_page_flag_set(m, PG_REFERENCED);
vm_page_sleep(m, "pgtblk");
continue;
}
/*
* We have a good page.
*/
vm_page_lock(m);
vm_page_wire(m);
vm_page_unlock(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;
}
VM_OBJECT_UNLOCK(obj);
/*
* Step 3, fixup the KVM pmap. Remember that
* bp->b_data is relative to bp->b_offset, but
* bp->b_offset may be offset into the first page.
*/
bp->b_data = (caddr_t)
trunc_page((vm_offset_t)bp->b_data);
pmap_qenter(
(vm_offset_t)bp->b_data,
bp->b_pages,
bp->b_npages
);
bp->b_data = (caddr_t)((vm_offset_t)bp->b_data |
(vm_offset_t)(bp->b_offset & PAGE_MASK));
}
}
if (newbsize < bp->b_bufsize)
bufspacewakeup();
bp->b_bufsize = newbsize; /* actual buffer allocation */
bp->b_bcount = size; /* requested buffer size */
return 1;
}
void
biodone(struct bio *bp)
{
struct mtx *mtxp;
void (*done)(struct bio *);
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
bp->bio_flags |= BIO_DONE;
done = bp->bio_done;
if (done == NULL)
wakeup(bp);
mtx_unlock(mtxp);
if (done != NULL)
done(bp);
}
/*
* Wait for a BIO to finish.
*
* XXX: resort to a timeout for now. The optimal locking (if any) for this
* case is not yet clear.
*/
int
biowait(struct bio *bp, const char *wchan)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
while ((bp->bio_flags & BIO_DONE) == 0)
msleep(bp, mtxp, PRIBIO, wchan, hz / 10);
mtx_unlock(mtxp);
if (bp->bio_error != 0)
return (bp->bio_error);
if (!(bp->bio_flags & BIO_ERROR))
return (0);
return (EIO);
}
void
biofinish(struct bio *bp, struct devstat *stat, int error)
{
if (error) {
bp->bio_error = error;
bp->bio_flags |= BIO_ERROR;
}
if (stat != NULL)
devstat_end_transaction_bio(stat, bp);
biodone(bp);
}
/*
* bufwait:
*
* Wait for buffer I/O completion, returning error status. The buffer
* is left locked and B_DONE on return. B_EINTR is converted into an EINTR
* error and cleared.
*/
int
bufwait(struct buf *bp)
{
if (bp->b_iocmd == BIO_READ)
bwait(bp, PRIBIO, "biord");
else
bwait(bp, PRIBIO, "biowr");
if (bp->b_flags & B_EINTR) {
bp->b_flags &= ~B_EINTR;
return (EINTR);
}
if (bp->b_ioflags & BIO_ERROR) {
return (bp->b_error ? bp->b_error : EIO);
} else {
return (0);
}
}
/*
* Call back function from struct bio back up to struct buf.
*/
static void
bufdonebio(struct bio *bip)
{
struct buf *bp;
bp = bip->bio_caller2;
bp->b_resid = bp->b_bcount - bip->bio_completed;
bp->b_resid = bip->bio_resid; /* XXX: remove */
bp->b_ioflags = bip->bio_flags;
bp->b_error = bip->bio_error;
if (bp->b_error)
bp->b_ioflags |= BIO_ERROR;
bufdone(bp);
g_destroy_bio(bip);
}
void
dev_strategy(struct cdev *dev, struct buf *bp)
{
struct cdevsw *csw;
struct bio *bip;
if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1)))
panic("b_iocmd botch");
for (;;) {
bip = g_new_bio();
if (bip != NULL)
break;
/* Try again later */
tsleep(&bp, PRIBIO, "dev_strat", hz/10);
}
bip->bio_cmd = bp->b_iocmd;
bip->bio_offset = bp->b_iooffset;
bip->bio_length = bp->b_bcount;
bip->bio_bcount = bp->b_bcount; /* XXX: remove */
bip->bio_data = bp->b_data;
bip->bio_done = bufdonebio;
bip->bio_caller2 = bp;
bip->bio_dev = dev;
KASSERT(dev->si_refcount > 0,
("dev_strategy on un-referenced struct cdev *(%s)",
devtoname(dev)));
csw = dev_refthread(dev);
if (csw == NULL) {
g_destroy_bio(bip);
bp->b_error = ENXIO;
bp->b_ioflags = BIO_ERROR;
bufdone(bp);
return;
}
(*csw->d_strategy)(bip);
dev_relthread(dev);
}
/*
* bufdone:
*
* Finish I/O on a buffer, optionally calling a completion function.
* This is usually called from an interrupt so process blocking is
* not allowed.
*
* biodone is also responsible for setting B_CACHE in a B_VMIO bp.
* In a non-VMIO bp, B_CACHE will be set on the next getblk()
* assuming B_INVAL is clear.
*
* For the VMIO case, we set B_CACHE if the op was a read and no
* read error occured, or if the op was a write. B_CACHE is never
* set if the buffer is invalid or otherwise uncacheable.
*
* biodone does not mess with B_INVAL, allowing the I/O routine or the
* initiator to leave B_INVAL set to brelse the buffer out of existance
* in the biodone routine.
*/
void
bufdone(struct buf *bp)
{
struct bufobj *dropobj;
void (*biodone)(struct buf *);
CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
dropobj = NULL;
KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp));
BUF_ASSERT_HELD(bp);
runningbufwakeup(bp);
if (bp->b_iocmd == BIO_WRITE)
dropobj = bp->b_bufobj;
/* call optional completion function if requested */
if (bp->b_iodone != NULL) {
biodone = bp->b_iodone;
bp->b_iodone = NULL;
(*biodone) (bp);
if (dropobj)
bufobj_wdrop(dropobj);
return;
}
bufdone_finish(bp);
if (dropobj)
bufobj_wdrop(dropobj);
}
void
bufdone_finish(struct buf *bp)
{
BUF_ASSERT_HELD(bp);
if (!LIST_EMPTY(&bp->b_dep))
buf_complete(bp);
if (bp->b_flags & B_VMIO) {
int i;
vm_ooffset_t foff;
vm_page_t m;
vm_object_t obj;
int iosize;
struct vnode *vp = bp->b_vp;
obj = bp->b_bufobj->bo_object;
#if defined(VFS_BIO_DEBUG)
mp_fixme("usecount and vflag accessed without locks.");
if (vp->v_usecount == 0) {
panic("biodone: zero vnode ref count");
}
KASSERT(vp->v_object != NULL,
("biodone: vnode %p has no vm_object", vp));
#endif
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("biodone: no buffer offset"));
VM_OBJECT_LOCK(obj);
#if defined(VFS_BIO_DEBUG)
if (obj->paging_in_progress < bp->b_npages) {
printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n",
obj->paging_in_progress, bp->b_npages);
}
#endif
/*
* Set B_CACHE if the op was a normal read and no error
* occured. B_CACHE is set for writes in the b*write()
* routines.
*/
iosize = bp->b_bcount - bp->b_resid;
if (bp->b_iocmd == BIO_READ &&
!(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
!(bp->b_ioflags & BIO_ERROR)) {
bp->b_flags |= B_CACHE;
}
for (i = 0; i < bp->b_npages; i++) {
int bogusflag = 0;
int resid;
resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff;
if (resid > iosize)
resid = iosize;
/*
* cleanup bogus pages, restoring the originals
*/
m = bp->b_pages[i];
if (m == bogus_page) {
bogusflag = 1;
m = vm_page_lookup(obj, OFF_TO_IDX(foff));
if (m == NULL)
panic("biodone: page disappeared!");
bp->b_pages[i] = m;
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
#if defined(VFS_BIO_DEBUG)
if (OFF_TO_IDX(foff) != m->pindex) {
printf(
"biodone: foff(%jd)/m->pindex(%ju) mismatch\n",
(intmax_t)foff, (uintmax_t)m->pindex);
}
#endif
/*
* In the write case, the valid and clean bits are
* already changed correctly ( see bdwrite() ), so we
* only need to do this here in the read case.
*/
if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) {
KASSERT((m->dirty & vm_page_bits(foff &
PAGE_MASK, resid)) == 0, ("bufdone_finish:"
" page %p has unexpected dirty bits", m));
vfs_page_set_valid(bp, foff, m);
}
/*
* when debugging new filesystems or buffer I/O methods, this
* is the most common error that pops up. if you see this, you
* have not set the page busy flag correctly!!!
*/
if (m->busy == 0) {
printf("biodone: page busy < 0, "
"pindex: %d, foff: 0x(%x,%x), "
"resid: %d, index: %d\n",
(int) m->pindex, (int)(foff >> 32),
(int) foff & 0xffffffff, resid, i);
if (!vn_isdisk(vp, NULL))
printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n",
(intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize,
(intmax_t) bp->b_lblkno,
bp->b_flags, bp->b_npages);
else
printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n",
(intmax_t) bp->b_lblkno,
bp->b_flags, bp->b_npages);
printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n",
(u_long)m->valid, (u_long)m->dirty,
m->wire_count);
panic("biodone: page busy < 0\n");
}
vm_page_io_finish(m);
vm_object_pip_subtract(obj, 1);
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
iosize -= resid;
}
vm_object_pip_wakeupn(obj, 0);
VM_OBJECT_UNLOCK(obj);
}
/*
* For asynchronous completions, release the buffer now. The brelse
* will do a wakeup there if necessary - so no need to do a wakeup
* here in the async case. The sync case always needs to do a wakeup.
*/
if (bp->b_flags & B_ASYNC) {
if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR))
brelse(bp);
else
bqrelse(bp);
} else
bdone(bp);
}
/*
* This routine is called in lieu of iodone in the case of
* incomplete I/O. This keeps the busy status for pages
* consistant.
*/
void
vfs_unbusy_pages(struct buf *bp)
{
int i;
vm_object_t obj;
vm_page_t m;
runningbufwakeup(bp);
if (!(bp->b_flags & B_VMIO))
return;
obj = bp->b_bufobj->bo_object;
VM_OBJECT_LOCK(obj);
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (m == bogus_page) {
m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i);
if (!m)
panic("vfs_unbusy_pages: page missing\n");
bp->b_pages[i] = m;
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
vm_object_pip_subtract(obj, 1);
vm_page_io_finish(m);
}
vm_object_pip_wakeupn(obj, 0);
VM_OBJECT_UNLOCK(obj);
}
/*
* vfs_page_set_valid:
*
* Set the valid bits in a page based on the supplied offset. The
* range is restricted to the buffer's size.
*
* This routine is typically called after a read completes.
*/
static void
vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m)
{
vm_ooffset_t eoff;
/*
* Compute the end offset, eoff, such that [off, eoff) does not span a
* page boundary and eoff is not greater than the end of the buffer.
* The end of the buffer, in this case, is our file EOF, not the
* allocation size of the buffer.
*/
eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK;
if (eoff > bp->b_offset + bp->b_bcount)
eoff = bp->b_offset + bp->b_bcount;
/*
* Set valid range. This is typically the entire buffer and thus the
* entire page.
*/
if (eoff > off)
vm_page_set_valid(m, off & PAGE_MASK, eoff - off);
}
/*
* vfs_page_set_validclean:
*
* Set the valid bits and clear the dirty bits in a page based on the
* supplied offset. The range is restricted to the buffer's size.
*/
static void
vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m)
{
vm_ooffset_t soff, eoff;
mtx_assert(&vm_page_queue_mtx, MA_OWNED);
/*
* Start and end offsets in buffer. eoff - soff may not cross a
* page boundry or cross the end of the buffer. The end of the
* buffer, in this case, is our file EOF, not the allocation size
* of the buffer.
*/
soff = off;
eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK;
if (eoff > bp->b_offset + bp->b_bcount)
eoff = bp->b_offset + bp->b_bcount;
/*
* Set valid range. This is typically the entire buffer and thus the
* entire page.
*/
if (eoff > soff) {
vm_page_set_validclean(
m,
(vm_offset_t) (soff & PAGE_MASK),
(vm_offset_t) (eoff - soff)
);
}
}
/*
* This routine is called before a device strategy routine.
* It is used to tell the VM system that paging I/O is in
* progress, and treat the pages associated with the buffer
* almost as being VPO_BUSY. Also the object paging_in_progress
* flag is handled to make sure that the object doesn't become
* inconsistant.
*
* Since I/O has not been initiated yet, certain buffer flags
* such as BIO_ERROR or B_INVAL may be in an inconsistant state
* and should be ignored.
*/
void
vfs_busy_pages(struct buf *bp, int clear_modify)
{
int i, bogus;
vm_object_t obj;
vm_ooffset_t foff;
vm_page_t m;
if (!(bp->b_flags & B_VMIO))
return;
obj = bp->b_bufobj->bo_object;
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("vfs_busy_pages: no buffer offset"));
VM_OBJECT_LOCK(obj);
if (bp->b_bufsize != 0)
vfs_setdirty_locked_object(bp);
retry:
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (vm_page_sleep_if_busy(m, FALSE, "vbpage"))
goto retry;
}
bogus = 0;
if (clear_modify)
vm_page_lock_queues();
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if ((bp->b_flags & B_CLUSTER) == 0) {
vm_object_pip_add(obj, 1);
vm_page_io_start(m);
}
/*
* When readying a buffer for a read ( i.e
* clear_modify == 0 ), it is important to do
* bogus_page replacement for valid pages in
* partially instantiated buffers. Partially
* instantiated buffers can, in turn, occur when
* reconstituting a buffer from its VM backing store
* base. We only have to do this if B_CACHE is
* clear ( which causes the I/O to occur in the
* first place ). The replacement prevents the read
* I/O from overwriting potentially dirty VM-backed
* pages. XXX bogus page replacement is, uh, bogus.
* It may not work properly with small-block devices.
* We need to find a better way.
*/
if (clear_modify) {
pmap_remove_write(m);
vfs_page_set_validclean(bp, foff, m);
} else if (m->valid == VM_PAGE_BITS_ALL &&
(bp->b_flags & B_CACHE) == 0) {
bp->b_pages[i] = bogus_page;
bogus++;
}
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
}
if (clear_modify)
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(obj);
if (bogus)
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
/*
* Tell the VM system that the pages associated with this buffer
* are clean. This is used for delayed writes where the data is
* going to go to disk eventually without additional VM intevention.
*
* Note that while we only really need to clean through to b_bcount, we
* just go ahead and clean through to b_bufsize.
*/
static void
vfs_clean_pages(struct buf *bp)
{
int i;
vm_ooffset_t foff, noff, eoff;
vm_page_t m;
if (!(bp->b_flags & B_VMIO))
return;
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("vfs_clean_pages: no buffer offset"));
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
vm_page_lock_queues();
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
eoff = noff;
if (eoff > bp->b_offset + bp->b_bufsize)
eoff = bp->b_offset + bp->b_bufsize;
vfs_page_set_validclean(bp, foff, m);
/* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
foff = noff;
}
vm_page_unlock_queues();
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
}
/*
* vfs_bio_set_valid:
*
* Set the range within the buffer to valid. 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_valid(struct buf *bp, int base, int size)
{
int i, n;
vm_page_t m;
if (!(bp->b_flags & B_VMIO))
return;
/*
* Fixup base to be relative to beginning of first page.
* Set initial n to be the maximum number of bytes in the
* first page that can be validated.
*/
base += (bp->b_offset & PAGE_MASK);
n = PAGE_SIZE - (base & PAGE_MASK);
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
m = bp->b_pages[i];
if (n > size)
n = size;
vm_page_set_valid(m, base & PAGE_MASK, n);
base += n;
size -= n;
n = PAGE_SIZE;
}
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
}
/*
* vfs_bio_clrbuf:
*
* If the specified buffer is a non-VMIO buffer, clear the entire
* buffer. If the specified buffer is a VMIO buffer, clear and
* validate only the previously invalid portions of the buffer.
* This routine essentially fakes an I/O, so we need to clear
* BIO_ERROR and B_INVAL.
*
* Note that while we only theoretically need to clear through b_bcount,
* we go ahead and clear through b_bufsize.
*/
void
vfs_bio_clrbuf(struct buf *bp)
{
int i, j, mask;
caddr_t sa, ea;
if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) {
clrbuf(bp);
return;
}
bp->b_flags &= ~B_INVAL;
bp->b_ioflags &= ~BIO_ERROR;
VM_OBJECT_LOCK(bp->b_bufobj->bo_object);
if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) &&
(bp->b_offset & PAGE_MASK) == 0) {
if (bp->b_pages[0] == bogus_page)
goto unlock;
mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1;
VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED);
if ((bp->b_pages[0]->valid & mask) == mask)
goto unlock;
if ((bp->b_pages[0]->valid & mask) == 0) {
bzero(bp->b_data, bp->b_bufsize);
bp->b_pages[0]->valid |= mask;
goto unlock;
}
}
ea = sa = bp->b_data;
for(i = 0; i < bp->b_npages; i++, sa = ea) {
ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE);
ea = (caddr_t)(vm_offset_t)ulmin(
(u_long)(vm_offset_t)ea,
(u_long)(vm_offset_t)bp->b_data + bp->b_bufsize);
if (bp->b_pages[i] == bogus_page)
continue;
j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE;
mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED);
if ((bp->b_pages[i]->valid & mask) == mask)
continue;
if ((bp->b_pages[i]->valid & mask) == 0)
bzero(sa, ea - sa);
else {
for (; sa < ea; sa += DEV_BSIZE, j++) {
if ((bp->b_pages[i]->valid & (1 << j)) == 0)
bzero(sa, DEV_BSIZE);
}
}
bp->b_pages[i]->valid |= mask;
}
unlock:
VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object);
bp->b_resid = 0;
}
/*
* vm_hold_load_pages and vm_hold_free_pages get pages into
* a buffers address space. The pages are anonymous and are
* not associated with a file object.
*/
static void
vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
{
vm_offset_t pg;
vm_page_t p;
int index;
to = round_page(to);
from = round_page(from);
index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
tryagain:
/*
* note: must allocate system pages since blocking here
* could interfere with paging I/O, no matter which
* process we are.
*/
p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ |
VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
if (!p) {
atomic_add_int(&vm_pageout_deficit,
(to - pg) >> PAGE_SHIFT);
VM_WAIT;
goto tryagain;
}
pmap_qenter(pg, &p, 1);
bp->b_pages[index] = p;
}
bp->b_npages = index;
}
/* Return pages associated with this buf to the vm system */
static void
vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
{
vm_offset_t pg;
vm_page_t p;
int index, newnpages;
from = round_page(from);
to = round_page(to);
newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
for (pg = from; pg < to; pg += PAGE_SIZE, index++) {
p = bp->b_pages[index];
if (p && (index < bp->b_npages)) {
if (p->busy) {
printf(
"vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
(intmax_t)bp->b_blkno,
(intmax_t)bp->b_lblkno);
}
bp->b_pages[index] = NULL;
pmap_qremove(pg, 1);
p->wire_count--;
vm_page_free(p);
atomic_subtract_int(&cnt.v_wire_count, 1);
}
}
bp->b_npages = newnpages;
}
/*
* Map an IO request into kernel virtual address space.
*
* All requests are (re)mapped into kernel VA space.
* Notice that we use b_bufsize for the size of the buffer
* to be mapped. b_bcount might be modified by the driver.
*
* Note that even if the caller determines that the address space should
* be valid, a race or a smaller-file mapped into a larger space may
* actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST
* check the return value.
*/
int
vmapbuf(struct buf *bp)
{
caddr_t addr, kva;
vm_prot_t prot;
int pidx, i;
struct vm_page *m;
struct pmap *pmap = &curproc->p_vmspace->vm_pmap;
if (bp->b_bufsize < 0)
return (-1);
prot = VM_PROT_READ;
if (bp->b_iocmd == BIO_READ)
prot |= VM_PROT_WRITE; /* Less backwards than it looks */
for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0;
addr < bp->b_data + bp->b_bufsize;
addr += PAGE_SIZE, pidx++) {
/*
* Do the vm_fault if needed; do the copy-on-write thing
* when reading stuff off device into memory.
*
* NOTE! Must use pmap_extract() because addr may be in
* the userland address space, and kextract is only guarenteed
* to work for the kernland address space (see: sparc64 port).
*/
retry:
if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data,
prot) < 0) {
for (i = 0; i < pidx; ++i) {
vm_page_lock(bp->b_pages[i]);
vm_page_unhold(bp->b_pages[i]);
vm_page_unlock(bp->b_pages[i]);
bp->b_pages[i] = NULL;
}
return(-1);
}
m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot);
if (m == NULL)
goto retry;
bp->b_pages[pidx] = m;
}
if (pidx > btoc(MAXPHYS))
panic("vmapbuf: mapped more than MAXPHYS");
pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
kva = bp->b_saveaddr;
bp->b_npages = pidx;
bp->b_saveaddr = bp->b_data;
bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK);
return(0);
}
/*
* Free the io map PTEs associated with this IO operation.
* We also invalidate the TLB entries and restore the original b_addr.
*/
void
vunmapbuf(struct buf *bp)
{
int pidx;
int npages;
npages = bp->b_npages;
pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
for (pidx = 0; pidx < npages; pidx++) {
vm_page_lock(bp->b_pages[pidx]);
vm_page_unhold(bp->b_pages[pidx]);
vm_page_unlock(bp->b_pages[pidx]);
}
bp->b_data = bp->b_saveaddr;
}
void
bdone(struct buf *bp)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
bp->b_flags |= B_DONE;
wakeup(bp);
mtx_unlock(mtxp);
}
void
bwait(struct buf *bp, u_char pri, const char *wchan)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
while ((bp->b_flags & B_DONE) == 0)
msleep(bp, mtxp, pri, wchan, 0);
mtx_unlock(mtxp);
}
int
bufsync(struct bufobj *bo, int waitfor)
{
return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread));
}
void
bufstrategy(struct bufobj *bo, struct buf *bp)
{
int i = 0;
struct vnode *vp;
vp = bp->b_vp;
KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy"));
KASSERT(vp->v_type != VCHR && vp->v_type != VBLK,
("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp));
i = VOP_STRATEGY(vp, bp);
KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp));
}
void
bufobj_wrefl(struct bufobj *bo)
{
KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
ASSERT_BO_LOCKED(bo);
bo->bo_numoutput++;
}
void
bufobj_wref(struct bufobj *bo)
{
KASSERT(bo != NULL, ("NULL bo in bufobj_wref"));
BO_LOCK(bo);
bo->bo_numoutput++;
BO_UNLOCK(bo);
}
void
bufobj_wdrop(struct bufobj *bo)
{
KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop"));
BO_LOCK(bo);
KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count"));
if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) {
bo->bo_flag &= ~BO_WWAIT;
wakeup(&bo->bo_numoutput);
}
BO_UNLOCK(bo);
}
int
bufobj_wwait(struct bufobj *bo, int slpflag, int timeo)
{
int error;
KASSERT(bo != NULL, ("NULL bo in bufobj_wwait"));
ASSERT_BO_LOCKED(bo);
error = 0;
while (bo->bo_numoutput) {
bo->bo_flag |= BO_WWAIT;
error = msleep(&bo->bo_numoutput, BO_MTX(bo),
slpflag | (PRIBIO + 1), "bo_wwait", timeo);
if (error)
break;
}
return (error);
}
void
bpin(struct buf *bp)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
bp->b_pin_count++;
mtx_unlock(mtxp);
}
void
bunpin(struct buf *bp)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
if (--bp->b_pin_count == 0)
wakeup(bp);
mtx_unlock(mtxp);
}
void
bunpin_wait(struct buf *bp)
{
struct mtx *mtxp;
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
while (bp->b_pin_count > 0)
msleep(bp, mtxp, PRIBIO, "bwunpin", 0);
mtx_unlock(mtxp);
}
#include "opt_ddb.h"
#ifdef DDB
#include <ddb/ddb.h>
/* DDB command to show buffer data */
DB_SHOW_COMMAND(buffer, db_show_buffer)
{
/* get args */
struct buf *bp = (struct buf *)addr;
if (!have_addr) {
db_printf("usage: show buffer <addr>\n");
return;
}
db_printf("buf at %p\n", bp);
db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS);
db_printf(
"b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n"
"b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_dep = %p\n",
bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid,
bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno,
bp->b_dep.lh_first);
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");
}
db_printf(" ");
lockmgr_printinfo(&bp->b_lock);
}
DB_SHOW_COMMAND(lockedbufs, lockedbufs)
{
struct buf *bp;
int i;
for (i = 0; i < nbuf; i++) {
bp = &buf[i];
if (BUF_ISLOCKED(bp)) {
db_show_buffer((uintptr_t)bp, 1, 0, NULL);
db_printf("\n");
}
}
}
DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs)
{
struct vnode *vp;
struct buf *bp;
if (!have_addr) {
db_printf("usage: show vnodebufs <addr>\n");
return;
}
vp = (struct vnode *)addr;
db_printf("Clean buffers:\n");
TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) {
db_show_buffer((uintptr_t)bp, 1, 0, NULL);
db_printf("\n");
}
db_printf("Dirty buffers:\n");
TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
db_show_buffer((uintptr_t)bp, 1, 0, NULL);
db_printf("\n");
}
}
#endif /* DDB */
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