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freebsd-skq/sys/kern/vfs_bio.c
Konstantin Belousov 904ed548bb When getnewbuf_reuse_bp() is called to reclaim some (clean) buffer, 
the vnode owning the buffer is not locked.  More, it cannot be locked
safely, since getnewbuf_reuse_bp() is called from newbuf(), and some
other vnode is already locked, for which reused buffer will be
reassigned.

As the consequence, reclamation of the owning vnode could go in
parallel, in particular, the call to vnode_destroy_vobject(), which
deallocates the vm object and zeroes the v_bufobj->bo_object.  Note
that the pages wired by the buffer are left wired and can be safely
freed by the vfs_vmio_release() without the need for the vm object
lock.  Also, seeing stale pointer to the v_object is safe due to vm
object type stability.

Check for bo_bufobj != NULL and cache the value in local variable to
avoid trying to lock NULL vm object.

Reported and tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2014-12-08 16:42:34 +00:00

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/*-
* Copyright (c) 2004 Poul-Henning Kamp
* Copyright (c) 1994,1997 John S. Dyson
* Copyright (c) 2013 The FreeBSD Foundation
* All rights reserved.
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
*
* 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/rwlock.h>
#include <sys/sysctl.h>
#include <sys/vmem.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_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 */
caddr_t unmapped_buf;
/* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
struct proc *bufdaemonproc;
static int inmem(struct vnode *vp, daddr_t blkno);
static void vm_hold_free_pages(struct buf *bp, int newbsize);
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_dirty_buf(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_flush(int);
static int flushbufqueues(int, int);
static void buf_daemon(void);
static void bremfreel(struct buf *bp);
static __inline void bd_wakeup(void);
static int sysctl_runningspace(SYSCTL_HANDLER_ARGS);
#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 unmapped_bufspace;
SYSCTL_LONG(_vfs, OID_AUTO, unmapped_bufspace, CTLFLAG_RD,
&unmapped_bufspace, 0,
"Amount of unmapped buffers, inclusive in the bufspace");
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_PROC(_vfs, OID_AUTO, lorunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
CTLFLAG_RW, &lorunningspace, 0, sysctl_runningspace, "L",
"Minimum preferred space used for in-progress I/O");
static long hirunningspace;
SYSCTL_PROC(_vfs, OID_AUTO, hirunningspace, CTLTYPE_LONG | CTLFLAG_MPSAFE |
CTLFLAG_RW, &hirunningspace, 0, sysctl_runningspace, "L",
"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 mappingrestarts;
SYSCTL_INT(_vfs, OID_AUTO, mappingrestarts, CTLFLAG_RW, &mappingrestarts, 0,
"Number of times getblk has had to restart a buffer mapping for "
"unmapped buffer");
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 notbufdflushes;
SYSCTL_LONG(_vfs, OID_AUTO, notbufdflushes, CTLFLAG_RD, &notbufdflushes, 0,
"Number of dirty buffer flushes done by the bufdaemon helpers");
static long barrierwrites;
SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0,
"Number of barrier writes");
SYSCTL_INT(_vfs, OID_AUTO, unmapped_buf_allowed, CTLFLAG_RD,
&unmapped_buf_allowed, 0,
"Permit the use of the unmapped i/o");
/*
* Lock for the non-dirty bufqueues
*/
static struct mtx_padalign bqclean;
/*
* Lock for the dirty queue.
*/
static struct mtx_padalign bqdirty;
/*
* This lock synchronizes access to bd_request.
*/
static struct mtx_padalign bdlock;
/*
* This lock protects the runningbufreq and synchronizes runningbufwakeup and
* waitrunningbufspace().
*/
static struct mtx_padalign rbreqlock;
/*
* Lock that protects needsbuffer and the sleeps/wakeups surrounding it.
*/
static struct rwlock_padalign nblock;
/*
* Lock that protects bdirtywait.
*/
static struct mtx_padalign bdirtylock;
/*
* 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;
/*
* 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;
/*
* 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(), bufcountadd(), bwillwrite(),
* getnewbuf(), and getblk().
*/
static volatile int needsbuffer;
/*
* Synchronization for bwillwrite() waiters.
*/
static int bdirtywait;
/*
* Definitions for the buffer free lists.
*/
#define BUFFER_QUEUES 5 /* 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_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */
#define QUEUE_EMPTY 4 /* 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 } };
#ifdef INVARIANTS
static int bq_len[BUFFER_QUEUES];
#endif
/*
* 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_FREE 0x04 /* wait for free bufs, hi hysteresis */
#define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */
static int
sysctl_runningspace(SYSCTL_HANDLER_ARGS)
{
long value;
int error;
value = *(long *)arg1;
error = sysctl_handle_long(oidp, &value, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
mtx_lock(&rbreqlock);
if (arg1 == &hirunningspace) {
if (value < lorunningspace)
error = EINVAL;
else
hirunningspace = value;
} else {
KASSERT(arg1 == &lorunningspace,
("%s: unknown arg1", __func__));
if (value > hirunningspace)
error = EINVAL;
else
lorunningspace = value;
}
mtx_unlock(&rbreqlock);
return (error);
}
#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
/*
* bqlock:
*
* Return the appropriate queue lock based on the index.
*/
static inline struct mtx *
bqlock(int qindex)
{
if (qindex == QUEUE_DIRTY)
return (struct mtx *)(&bqdirty);
return (struct mtx *)(&bqclean);
}
/*
* bdirtywakeup:
*
* Wakeup any bwillwrite() waiters.
*/
static void
bdirtywakeup(void)
{
mtx_lock(&bdirtylock);
if (bdirtywait) {
bdirtywait = 0;
wakeup(&bdirtywait);
}
mtx_unlock(&bdirtylock);
}
/*
* bdirtysub:
*
* Decrement the numdirtybuffers count by one and wakeup any
* threads blocked in bwillwrite().
*/
static void
bdirtysub(void)
{
if (atomic_fetchadd_int(&numdirtybuffers, -1) ==
(lodirtybuffers + hidirtybuffers) / 2)
bdirtywakeup();
}
/*
* bdirtyadd:
*
* Increment the numdirtybuffers count by one and wakeup the buf
* daemon if needed.
*/
static void
bdirtyadd(void)
{
/*
* Only do the wakeup once as we cross the boundary. The
* buf daemon will keep running until the condition clears.
*/
if (atomic_fetchadd_int(&numdirtybuffers, 1) ==
(lodirtybuffers + hidirtybuffers) / 2)
bd_wakeup();
}
/*
* 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)
{
int need_wakeup, on;
/*
* 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.
*/
rw_rlock(&nblock);
for (;;) {
need_wakeup = 0;
on = needsbuffer;
if ((on & VFS_BIO_NEED_BUFSPACE) == 0)
break;
need_wakeup = 1;
if (atomic_cmpset_rel_int(&needsbuffer, on,
on & ~VFS_BIO_NEED_BUFSPACE))
break;
}
if (need_wakeup)
wakeup(__DEVOLATILE(void *, &needsbuffer));
rw_runlock(&nblock);
}
/*
* runningwakeup:
*
* Wake up processes that are waiting on asynchronous writes to fall
* below lorunningspace.
*/
static void
runningwakeup(void)
{
mtx_lock(&rbreqlock);
if (runningbufreq) {
runningbufreq = 0;
wakeup(&runningbufreq);
}
mtx_unlock(&rbreqlock);
}
/*
* runningbufwakeup:
*
* Decrement the outstanding write count according.
*/
void
runningbufwakeup(struct buf *bp)
{
long space, bspace;
bspace = bp->b_runningbufspace;
if (bspace == 0)
return;
space = atomic_fetchadd_long(&runningbufspace, -bspace);
KASSERT(space >= bspace, ("runningbufspace underflow %ld %ld",
space, bspace));
bp->b_runningbufspace = 0;
/*
* Only acquire the lock and wakeup on the transition from exceeding
* the threshold to falling below it.
*/
if (space < lorunningspace)
return;
if (space - bspace > lorunningspace)
return;
runningwakeup();
}
/*
* bufcountadd:
*
* 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
bufcountadd(struct buf *bp)
{
int mask, need_wakeup, old, on;
KASSERT((bp->b_flags & B_INFREECNT) == 0,
("buf %p already counted as free", bp));
bp->b_flags |= B_INFREECNT;
old = atomic_fetchadd_int(&numfreebuffers, 1);
KASSERT(old >= 0 && old < nbuf,
("numfreebuffers climbed to %d", old + 1));
mask = VFS_BIO_NEED_ANY;
if (numfreebuffers >= hifreebuffers)
mask |= VFS_BIO_NEED_FREE;
rw_rlock(&nblock);
for (;;) {
need_wakeup = 0;
on = needsbuffer;
if (on == 0)
break;
need_wakeup = 1;
if (atomic_cmpset_rel_int(&needsbuffer, on, on & ~mask))
break;
}
if (need_wakeup)
wakeup(__DEVOLATILE(void *, &needsbuffer));
rw_runlock(&nblock);
}
/*
* bufcountsub:
*
* Decrement the numfreebuffers count as needed.
*/
static void
bufcountsub(struct buf *bp)
{
int old;
/*
* 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) {
KASSERT((bp->b_flags & B_INFREECNT) != 0,
("buf %p not counted in numfreebuffers", bp));
bp->b_flags &= ~B_INFREECNT;
old = atomic_fetchadd_int(&numfreebuffers, -1);
KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1));
}
}
/*
* 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.
*
* 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 = 1;
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_ASSERT_LOCKED(m->object);
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(void)
{
mtx_lock(&bdlock);
if (bd_request == 0) {
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);
}
#ifndef NSWBUF_MIN
#define NSWBUF_MIN 16
#endif
#ifdef __i386__
#define TRANSIENT_DENOM 5
#else
#define TRANSIENT_DENOM 10
#endif
/*
* 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, maxbuf_sz, buf_sz, biotmap_sz;
/*
* 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 += min((physmem_est - 65536) * 2 / (factor * 5),
32 * 1024 * 1024 / (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;
}
/*
* Ideal allocation size for the transient bio submap is 10%
* of the maximal space buffer map. This roughly corresponds
* to the amount of the buffer mapped for typical UFS load.
*
* Clip the buffer map to reserve space for the transient
* BIOs, if its extent is bigger than 90% (80% on i386) of the
* maximum buffer map extent on the platform.
*
* The fall-back to the maxbuf in case of maxbcache unset,
* allows to not trim the buffer KVA for the architectures
* with ample KVA space.
*/
if (bio_transient_maxcnt == 0 && unmapped_buf_allowed) {
maxbuf_sz = maxbcache != 0 ? maxbcache : maxbuf * BKVASIZE;
buf_sz = (long)nbuf * BKVASIZE;
if (buf_sz < maxbuf_sz / TRANSIENT_DENOM *
(TRANSIENT_DENOM - 1)) {
/*
* There is more KVA than memory. Do not
* adjust buffer map size, and assign the rest
* of maxbuf to transient map.
*/
biotmap_sz = maxbuf_sz - buf_sz;
} else {
/*
* Buffer map spans all KVA we could afford on
* this platform. Give 10% (20% on i386) of
* the buffer map to the transient bio map.
*/
biotmap_sz = buf_sz / TRANSIENT_DENOM;
buf_sz -= biotmap_sz;
}
if (biotmap_sz / INT_MAX > MAXPHYS)
bio_transient_maxcnt = INT_MAX;
else
bio_transient_maxcnt = biotmap_sz / MAXPHYS;
/*
* Artifically limit to 1024 simultaneous in-flight I/Os
* using the transient mapping.
*/
if (bio_transient_maxcnt > 1024)
bio_transient_maxcnt = 1024;
if (tuned_nbuf)
nbuf = buf_sz / BKVASIZE;
}
/*
* 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 = min(nbuf / 4, 256);
TUNABLE_INT_FETCH("kern.nswbuf", &nswbuf);
if (nswbuf < NSWBUF_MIN)
nswbuf = NSWBUF_MIN;
/*
* 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(&bqclean, "bufq clean lock", NULL, MTX_DEF);
mtx_init(&bqdirty, "bufq dirty lock", NULL, MTX_DEF);
mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF);
rw_init(&nblock, "needsbuffer lock");
mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF);
mtx_init(&bdirtylock, "dirty buf 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 | B_INFREECNT;
bp->b_rcred = NOCRED;
bp->b_wcred = NOCRED;
bp->b_qindex = QUEUE_EMPTY;
bp->b_xflags = 0;
LIST_INIT(&bp->b_dep);
BUF_LOCKINIT(bp);
TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
#ifdef INVARIANTS
bq_len[QUEUE_EMPTY]++;
#endif
}
/*
* 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;
/*
* Note: The 16 MiB upper limit for hirunningspace was chosen
* arbitrarily and may need further tuning. It corresponds to
* 128 outstanding write IO requests (if IO size is 128 KiB),
* which fits with many RAID controllers' tagged queuing limits.
* The lower 1 MiB limit is the historical upper limit for
* hirunningspace.
*/
hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE),
16 * 1024 * 1024), 1024 * 1024);
lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE);
/*
* 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 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);
unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
}
#ifdef INVARIANTS
static inline void
vfs_buf_check_mapped(struct buf *bp)
{
KASSERT((bp->b_flags & B_UNMAPPED) == 0,
("mapped buf %p %x", bp, bp->b_flags));
KASSERT(bp->b_kvabase != unmapped_buf,
("mapped buf: b_kvabase was not updated %p", bp));
KASSERT(bp->b_data != unmapped_buf,
("mapped buf: b_data was not updated %p", bp));
}
static inline void
vfs_buf_check_unmapped(struct buf *bp)
{
KASSERT((bp->b_flags & B_UNMAPPED) == B_UNMAPPED,
("unmapped buf %p %x", bp, bp->b_flags));
KASSERT(bp->b_kvabase == unmapped_buf,
("unmapped buf: corrupted b_kvabase %p", bp));
KASSERT(bp->b_data == unmapped_buf,
("unmapped buf: corrupted b_data %p", bp));
}
#define BUF_CHECK_MAPPED(bp) vfs_buf_check_mapped(bp)
#define BUF_CHECK_UNMAPPED(bp) vfs_buf_check_unmapped(bp)
#else
#define BUF_CHECK_MAPPED(bp) do {} while (0)
#define BUF_CHECK_UNMAPPED(bp) do {} while (0)
#endif
static void
bpmap_qenter(struct buf *bp)
{
BUF_CHECK_MAPPED(bp);
/*
* 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));
}
/*
* 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 == 0)
return;
atomic_add_int(&buffreekvacnt, 1);
atomic_subtract_long(&bufspace, bp->b_kvasize);
if ((bp->b_flags & B_UNMAPPED) == 0) {
BUF_CHECK_MAPPED(bp);
vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase,
bp->b_kvasize);
} else {
BUF_CHECK_UNMAPPED(bp);
if ((bp->b_flags & B_KVAALLOC) != 0) {
vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc,
bp->b_kvasize);
}
atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
}
bp->b_kvasize = 0;
bufspacewakeup();
}
/*
* binsfree:
*
* Insert the buffer into the appropriate free list.
*/
static void
binsfree(struct buf *bp, int qindex)
{
struct mtx *olock, *nlock;
BUF_ASSERT_XLOCKED(bp);
olock = bqlock(bp->b_qindex);
nlock = bqlock(qindex);
mtx_lock(olock);
/* Handle delayed bremfree() processing. */
if (bp->b_flags & B_REMFREE)
bremfreel(bp);
if (bp->b_qindex != QUEUE_NONE)
panic("binsfree: free buffer onto another queue???");
bp->b_qindex = qindex;
if (olock != nlock) {
mtx_unlock(olock);
mtx_lock(nlock);
}
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);
#ifdef INVARIANTS
bq_len[bp->b_qindex]++;
#endif
mtx_unlock(nlock);
/*
* Something we can maybe free or reuse.
*/
if (bp->b_bufsize && !(bp->b_flags & B_DELWRI))
bufspacewakeup();
if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))
bufcountadd(bp);
}
/*
* bremfree:
*
* Mark the buffer for removal from the appropriate free list.
*
*/
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_XLOCKED(bp);
bp->b_flags |= B_REMFREE;
bufcountsub(bp);
}
/*
* 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)
{
struct mtx *qlock;
qlock = bqlock(bp->b_qindex);
mtx_lock(qlock);
bremfreel(bp);
mtx_unlock(qlock);
}
/*
* bremfreel:
*
* Removes a buffer from the free list, must be called with the
* correct qlock 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_XLOCKED(bp);
mtx_assert(bqlock(bp->b_qindex), MA_OWNED);
TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist);
#ifdef INVARIANTS
KASSERT(bq_len[bp->b_qindex] >= 1, ("queue %d underflow",
bp->b_qindex));
bq_len[bp->b_qindex]--;
#endif
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;
}
bufcountsub(bp);
}
/*
* 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);
}
}
}
/*
* Entry point for bread() and breadn() via #defines in sys/buf.h.
*
* 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(). Also starts asynchronous I/O on read-ahead blocks.
*/
int
breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno,
int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp)
{
struct buf *bp;
int rv = 0, readwait = 0;
CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size);
/*
* Can only return NULL if GB_LOCK_NOWAIT flag is specified.
*/
*bpp = bp = getblk(vp, blkno, size, 0, 0, flags);
if (bp == NULL)
return (EBUSY);
/* 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;
long space;
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);
}
if (bp->b_flags & B_BARRIER)
barrierwrites++;
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. Increment the bufobj write count
* before bundirty() call, to prevent other thread from seeing
* empty dirty list and zero counter for writes in progress,
* falsely indicating that the bufobj is clean.
*/
bufobj_wref(bp->b_bufobj);
bundirty(bp);
bp->b_flags &= ~B_DONE;
bp->b_ioflags &= ~BIO_ERROR;
bp->b_flags |= B_CACHE;
bp->b_iocmd = BIO_WRITE;
vfs_busy_pages(bp, 1);
/*
* Normal bwrites pipeline writes
*/
bp->b_runningbufspace = bp->b_bufsize;
space = atomic_fetchadd_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 if (space > hirunningspace) {
/*
* 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));
KASSERT((bp->b_flags & B_BARRIER) == 0,
("Barrier request in delayed write %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.
*
* Mark the buffer pages as clean. 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_dirty_buf(bp);
bqrelse(bp);
/*
* 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);
bdirtyadd();
}
}
/*
* 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);
bdirtysub();
}
/*
* 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);
}
/*
* babarrierwrite:
*
* Asynchronous barrier write. Start output on a buffer, but do not
* wait for it to complete. Place a write barrier after this write so
* that this buffer and all buffers written before it are committed to
* the disk before any buffers written after this write are committed
* to the disk. The buffer is released when the output completes.
*/
void
babarrierwrite(struct buf *bp)
{
bp->b_flags |= B_ASYNC | B_BARRIER;
(void) bwrite(bp);
}
/*
* bbarrierwrite:
*
* Synchronous barrier write. Start output on a buffer and wait for
* it to complete. Place a write barrier after this write so that
* this buffer and all buffers written before it are committed to
* the disk before any buffers written after this write are committed
* to the disk. The buffer is released when the output completes.
*/
int
bbarrierwrite(struct buf *bp)
{
bp->b_flags |= B_BARRIER;
return (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(&bdirtylock);
while (numdirtybuffers >= hidirtybuffers) {
bdirtywait = 1;
msleep(&bdirtywait, &bdirtylock, (PRIBIO + 4),
"flswai", 0);
}
mtx_unlock(&bdirtylock);
}
}
/*
* 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)
{
int qindex;
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 (BUF_LOCKRECURSED(bp)) {
/*
* Do not process, in particular, do not handle the
* B_INVAL/B_RELBUF and do not release to free list.
*/
BUF_UNLOCK(bp);
return;
}
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)
bdirtysub();
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()) {
/*
* BKGRDINPROG can only be set with the buf and bufobj
* locks both held. We tolerate a race to clear it here.
*/
if (!(bp->b_vflags & BV_BKGRDINPROG))
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;
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;
VM_OBJECT_RLOCK(obj);
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;
}
}
VM_OBJECT_RUNLOCK(obj);
if ((bp->b_flags & (B_INVAL | B_UNMAPPED)) == 0) {
BUF_CHECK_MAPPED(bp);
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_OBJECT_WLOCK(obj);
while (vm_page_xbusied(m)) {
vm_page_lock(m);
VM_OBJECT_WUNLOCK(obj);
vm_page_busy_sleep(m, "mbncsh");
VM_OBJECT_WLOCK(obj);
}
if (pmap_page_wired_mappings(m) == 0)
vm_page_set_invalid(m, poffset, presid);
VM_OBJECT_WUNLOCK(obj);
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;
}
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 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)
qindex = QUEUE_EMPTYKVA;
else
qindex = QUEUE_EMPTY;
bp->b_flags |= B_AGE;
/* 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");
qindex = QUEUE_CLEAN;
bp->b_flags |= B_AGE;
/* remaining buffers */
} else if (bp->b_flags & B_DELWRI)
qindex = QUEUE_DIRTY;
else
qindex = QUEUE_CLEAN;
binsfree(bp, qindex);
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)
{
int qindex;
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;
}
bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
if (bp->b_flags & B_MANAGED) {
if (bp->b_flags & B_REMFREE)
bremfreef(bp);
goto out;
}
/* buffers with stale but valid contents */
if (bp->b_flags & B_DELWRI) {
qindex = QUEUE_DIRTY;
} else {
if ((bp->b_flags & B_DELWRI) == 0 &&
(bp->b_xflags & BX_VNDIRTY))
panic("bqrelse: not dirty");
/*
* BKGRDINPROG can only be set with the buf and bufobj
* locks both held. We tolerate a race to clear it here.
*/
if (buf_vm_page_count_severe() &&
(bp->b_vflags & BV_BKGRDINPROG) == 0) {
/*
* 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*.
*/
brelse(bp);
return;
}
qindex = QUEUE_CLEAN;
}
binsfree(bp, qindex);
out:
/* 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)
{
vm_object_t obj;
vm_page_t m;
int i;
if ((bp->b_flags & B_UNMAPPED) == 0) {
BUF_CHECK_MAPPED(bp);
pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
} else
BUF_CHECK_UNMAPPED(bp);
obj = bp->b_bufobj->bo_object;
if (obj != NULL)
VM_OBJECT_WLOCK(obj);
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_unwire(m, PQ_INACTIVE);
/*
* 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) {
if (m->wire_count == 0 && !vm_page_busied(m))
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(m);
}
if (obj != NULL)
VM_OBJECT_WUNLOCK(obj);
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;
int gbflags;
bo = &vp->v_bufobj;
gbflags = (bp->b_flags & B_UNMAPPED) != 0 ? GB_UNMAPPED : 0;
/*
* 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_RLOCK(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_RUNLOCK(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,
gbflags);
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);
}
static void
setbufkva(struct buf *bp, vm_offset_t addr, int maxsize, int gbflags)
{
KASSERT((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 &&
bp->b_kvasize == 0, ("call bfreekva(%p)", bp));
if ((gbflags & GB_UNMAPPED) == 0) {
bp->b_kvabase = (caddr_t)addr;
} else if ((gbflags & GB_KVAALLOC) != 0) {
KASSERT((gbflags & GB_UNMAPPED) != 0,
("GB_KVAALLOC without GB_UNMAPPED"));
bp->b_kvaalloc = (caddr_t)addr;
bp->b_flags |= B_UNMAPPED | B_KVAALLOC;
atomic_add_long(&unmapped_bufspace, bp->b_kvasize);
}
bp->b_kvasize = maxsize;
}
/*
* Allocate the buffer KVA and set b_kvasize. Also set b_kvabase if
* needed.
*/
static int
allocbufkva(struct buf *bp, int maxsize, int gbflags)
{
vm_offset_t addr;
bfreekva(bp);
addr = 0;
if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) {
/*
* Buffer map is too fragmented. Request the caller
* to defragment the map.
*/
atomic_add_int(&bufdefragcnt, 1);
return (1);
}
setbufkva(bp, addr, maxsize, gbflags);
atomic_add_long(&bufspace, bp->b_kvasize);
return (0);
}
/*
* Ask the bufdaemon for help, or act as bufdaemon itself, when a
* locked vnode is supplied.
*/
static void
getnewbuf_bufd_help(struct vnode *vp, int gbflags, int slpflag, int slptimeo,
int defrag)
{
struct thread *td;
char *waitmsg;
int cnt, error, flags, norunbuf, wait;
mtx_assert(&bqclean, MA_OWNED);
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;
}
atomic_set_int(&needsbuffer, flags);
mtx_unlock(&bqclean);
bd_speedup(); /* heeeelp */
if ((gbflags & GB_NOWAIT_BD) != 0)
return;
td = curthread;
cnt = 0;
wait = MNT_NOWAIT;
rw_wlock(&nblock);
while ((needsbuffer & flags) != 0) {
if (vp != NULL && vp->v_type != VCHR &&
(td->td_pflags & TDP_BUFNEED) == 0) {
rw_wunlock(&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.
*/
if (cnt++ > 2)
wait = MNT_WAIT;
ASSERT_VOP_LOCKED(vp, "bufd_helper");
error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
vn_lock(vp, LK_TRYUPGRADE);
if (error == 0) {
/* play bufdaemon */
norunbuf = curthread_pflags_set(TDP_BUFNEED |
TDP_NORUNNINGBUF);
VOP_FSYNC(vp, wait, td);
atomic_add_long(&notbufdflushes, 1);
curthread_pflags_restore(norunbuf);
}
rw_wlock(&nblock);
if ((needsbuffer & flags) == 0)
break;
}
error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock,
(PRIBIO + 4) | slpflag, waitmsg, slptimeo);
if (error != 0)
break;
}
rw_wunlock(&nblock);
}
static void
getnewbuf_reuse_bp(struct buf *bp, int qindex)
{
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);
mtx_assert(&bqclean, MA_NOTOWNED);
/*
* 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));
if (qindex == QUEUE_CLEAN) {
if (bp->b_flags & B_VMIO) {
bp->b_flags &= ~B_ASYNC;
vfs_vmio_release(bp);
}
if (bp->b_vp != NULL)
brelvp(bp);
}
/*
* 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 &= B_UNMAPPED | B_KVAALLOC;
bp->b_ioflags = 0;
bp->b_xflags = 0;
KASSERT((bp->b_flags & B_INFREECNT) == 0,
("buf %p still counted as free?", bp));
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);
}
static int flushingbufs;
static struct buf *
getnewbuf_scan(int maxsize, int defrag, int unmapped, int metadata)
{
struct buf *bp, *nbp;
int nqindex, qindex, pass;
KASSERT(!unmapped || !defrag, ("both unmapped and defrag"));
pass = 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
* for the allocation of the mapped buffer. For unmapped, the
* easiest is to start with EMPTY outright.
*
* 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.
*/
nbp = NULL;
mtx_lock(&bqclean);
if (!defrag && unmapped) {
nqindex = QUEUE_EMPTY;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
}
if (nbp == NULL) {
nqindex = QUEUE_EMPTYKVA;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
}
/*
* 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 (nbp == NULL && (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. No KVA is needed
* for the unmapped allocation.
*/
if (nbp == NULL && defrag == 0 && (bufspace + maxsize < hibufspace ||
metadata)) {
nqindex = QUEUE_EMPTY;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
}
/*
* All available buffers might be clean, retry ignoring the
* lobufspace as the last resort.
*/
if (nbp == NULL && !TAILQ_EMPTY(&bufqueues[QUEUE_CLEAN])) {
nqindex = QUEUE_CLEAN;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
}
/*
* Run scan, possibly freeing data and/or kva mappings on the fly
* depending.
*/
while ((bp = nbp) != NULL) {
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;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]);
if (nbp != NULL)
break;
/* FALLTHROUGH */
case QUEUE_EMPTYKVA:
nqindex = QUEUE_CLEAN;
nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]);
if (nbp != NULL)
break;
/* FALLTHROUGH */
case QUEUE_CLEAN:
if (metadata && pass == 1) {
pass = 2;
nqindex = QUEUE_EMPTY;
nbp = TAILQ_FIRST(
&bufqueues[QUEUE_EMPTY]);
}
/*
* 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;
/*
* BKGRDINPROG can only be set with the buf and bufobj
* locks both held. We tolerate a race to clear it here.
*/
if (bp->b_vflags & BV_BKGRDINPROG) {
BUF_UNLOCK(bp);
continue;
}
KASSERT(bp->b_qindex == qindex,
("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
bremfreel(bp);
mtx_unlock(&bqclean);
/*
* NOTE: nbp is now entirely invalid. We can only restart
* the scan from this point on.
*/
getnewbuf_reuse_bp(bp, qindex);
mtx_assert(&bqclean, MA_NOTOWNED);
/*
* 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 (metadata)
break;
/*
* 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;
}
return (bp);
}
/*
* 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_arena is too fragmented ( space reservation fails )
* If we have to flush dirty buffers ( but we try to avoid this )
*/
static struct buf *
getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize,
int gbflags)
{
struct buf *bp;
int defrag, metadata;
KASSERT((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
if (!unmapped_buf_allowed)
gbflags &= ~(GB_UNMAPPED | GB_KVAALLOC);
defrag = 0;
if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
vp->v_type == VCHR)
metadata = 1;
else
metadata = 0;
/*
* 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:
bp = getnewbuf_scan(maxsize, defrag, (gbflags & (GB_UNMAPPED |
GB_KVAALLOC)) == GB_UNMAPPED, metadata);
if (bp != NULL)
defrag = 0;
/*
* 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) {
mtx_assert(&bqclean, MA_OWNED);
getnewbuf_bufd_help(vp, gbflags, slpflag, slptimeo, defrag);
mtx_assert(&bqclean, MA_NOTOWNED);
} else if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == GB_UNMAPPED) {
mtx_assert(&bqclean, MA_NOTOWNED);
bfreekva(bp);
bp->b_flags |= B_UNMAPPED;
bp->b_kvabase = bp->b_data = unmapped_buf;
bp->b_kvasize = maxsize;
atomic_add_long(&bufspace, bp->b_kvasize);
atomic_add_long(&unmapped_bufspace, bp->b_kvasize);
atomic_add_int(&bufreusecnt, 1);
} else {
mtx_assert(&bqclean, MA_NOTOWNED);
/*
* 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 || (bp->b_flags & (B_UNMAPPED |
B_KVAALLOC)) == B_UNMAPPED) {
if (allocbufkva(bp, maxsize, gbflags)) {
defrag = 1;
bp->b_flags |= B_INVAL;
brelse(bp);
goto restart;
}
atomic_add_int(&bufreusecnt, 1);
} else if ((bp->b_flags & B_KVAALLOC) != 0 &&
(gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == 0) {
/*
* If the reused buffer has KVA allocated,
* reassign b_kvaalloc to b_kvabase.
*/
bp->b_kvabase = bp->b_kvaalloc;
bp->b_flags &= ~B_KVAALLOC;
atomic_subtract_long(&unmapped_bufspace,
bp->b_kvasize);
atomic_add_int(&bufreusecnt, 1);
} else if ((bp->b_flags & (B_UNMAPPED | B_KVAALLOC)) == 0 &&
(gbflags & (GB_UNMAPPED | GB_KVAALLOC)) == (GB_UNMAPPED |
GB_KVAALLOC)) {
/*
* The case of reused buffer already have KVA
* mapped, but the request is for unmapped
* buffer with KVA allocated.
*/
bp->b_kvaalloc = bp->b_kvabase;
bp->b_data = bp->b_kvabase = unmapped_buf;
bp->b_flags |= B_UNMAPPED | B_KVAALLOC;
atomic_add_long(&unmapped_bufspace,
bp->b_kvasize);
atomic_add_int(&bufreusecnt, 1);
}
if ((gbflags & GB_UNMAPPED) == 0) {
bp->b_saveaddr = bp->b_kvabase;
bp->b_data = bp->b_saveaddr;
bp->b_flags &= ~B_UNMAPPED;
BUF_CHECK_MAPPED(bp);
}
}
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_flush(int target)
{
int flushed;
flushed = flushbufqueues(target, 0);
if (flushed == 0) {
/*
* Could not find any buffers without rollback
* dependencies, so just write the first one
* in the hopes of eventually making progress.
*/
flushed = flushbufqueues(target, 1);
}
return (flushed);
}
static void
buf_daemon()
{
int lodirty;
/*
* 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);
lodirty = lodirtybuffers;
if (bd_speedupreq) {
lodirty = 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.
*/
while (numdirtybuffers > lodirty) {
if (buf_flush(numdirtybuffers - lodirty) == 0)
break;
kern_yield(PRI_USER);
}
/*
* 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 for a short period
* to avoid endless loops on unlockable buffers.
*/
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;
/*
* Do an extra wakeup in case dirty threshold
* changed via sysctl and the explicit transition
* out of shortfall was missed.
*/
bdirtywakeup();
if (runningbufspace <= lorunningspace)
runningwakeup();
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(int target, int flushdeps)
{
struct buf *sentinel;
struct vnode *vp;
struct mount *mp;
struct buf *bp;
int hasdeps;
int flushed;
int queue;
int error;
flushed = 0;
queue = QUEUE_DIRTY;
bp = NULL;
sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO);
sentinel->b_qindex = QUEUE_SENTINEL;
mtx_lock(&bqdirty);
TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
mtx_unlock(&bqdirty);
while (flushed != target) {
maybe_yield();
mtx_lock(&bqdirty);
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 {
mtx_unlock(&bqdirty);
break;
}
KASSERT(bp->b_qindex != QUEUE_SENTINEL,
("parallel calls to flushbufqueues() bp %p", bp));
error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
mtx_unlock(&bqdirty);
if (error != 0)
continue;
if (bp->b_pin_count > 0) {
BUF_UNLOCK(bp);
continue;
}
/*
* BKGRDINPROG can only be set with the buf and bufobj
* locks both held. We tolerate a race to clear it here.
*/
if ((bp->b_vflags & BV_BKGRDINPROG) != 0 ||
(bp->b_flags & B_DELWRI) == 0) {
BUF_UNLOCK(bp);
continue;
}
if (bp->b_flags & B_INVAL) {
bremfreef(bp);
brelse(bp);
flushed++;
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;
}
error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
if (error == 0) {
CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
vfs_bio_awrite(bp);
vn_finished_write(mp);
VOP_UNLOCK(vp, 0);
flushwithdeps += hasdeps;
flushed++;
if (runningbufspace > hirunningspace)
waitrunningbufspace();
continue;
}
vn_finished_write(mp);
BUF_UNLOCK(bp);
}
mtx_lock(&bqdirty);
TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
mtx_unlock(&bqdirty);
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_RLOCK(bo);
bp = gbincore(bo, blkno);
BO_RUNLOCK(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_RLOCK(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_RUNLOCK(obj);
return 1;
notinmem:
VM_OBJECT_RUNLOCK(obj);
return (0);
}
/*
* Set 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.
*
* 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_dirty_buf(struct buf *bp)
{
vm_ooffset_t foff, noff, eoff;
vm_page_t m;
int i;
if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0)
return;
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("vfs_clean_pages_dirty_buf: no buffer offset"));
VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
vfs_drain_busy_pages(bp);
vfs_setdirty_locked_object(bp);
for (i = 0; i < bp->b_npages; 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;
m = bp->b_pages[i];
vfs_page_set_validclean(bp, foff, m);
/* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */
foff = noff;
}
VM_OBJECT_WUNLOCK(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_ASSERT_WLOCKED(object);
/*
* We qualify the scan for modified pages on whether the
* object has been flushed yet.
*/
if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) {
vm_offset_t boffset;
vm_offset_t eoffset;
/*
* test the pages to see if they have been modified directly
* by users through the VM system.
*/
for (i = 0; i < bp->b_npages; i++)
vm_page_test_dirty(bp->b_pages[i]);
/*
* Calculate the encompassing dirty range, boffset and eoffset,
* (eoffset - boffset) bytes.
*/
for (i = 0; i < bp->b_npages; i++) {
if (bp->b_pages[i]->dirty)
break;
}
boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
for (i = bp->b_npages - 1; i >= 0; --i) {
if (bp->b_pages[i]->dirty) {
break;
}
}
eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK);
/*
* Fit it to the buffer.
*/
if (eoffset > bp->b_bcount)
eoffset = bp->b_bcount;
/*
* If we have a good dirty range, merge with the existing
* dirty range.
*/
if (boffset < eoffset) {
if (bp->b_dirtyoff > boffset)
bp->b_dirtyoff = boffset;
if (bp->b_dirtyend < eoffset)
bp->b_dirtyend = eoffset;
}
}
}
/*
* Allocate the KVA mapping for an existing buffer. It handles the
* cases of both B_UNMAPPED buffer, and buffer with the preallocated
* KVA which is not mapped (B_KVAALLOC).
*/
static void
bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
{
struct buf *scratch_bp;
int bsize, maxsize, need_mapping, need_kva;
off_t offset;
need_mapping = (bp->b_flags & B_UNMAPPED) != 0 &&
(gbflags & GB_UNMAPPED) == 0;
need_kva = (bp->b_flags & (B_KVAALLOC | B_UNMAPPED)) == B_UNMAPPED &&
(gbflags & GB_KVAALLOC) != 0;
if (!need_mapping && !need_kva)
return;
BUF_CHECK_UNMAPPED(bp);
if (need_mapping && (bp->b_flags & B_KVAALLOC) != 0) {
/*
* Buffer is not mapped, but the KVA was already
* reserved at the time of the instantiation. Use the
* allocated space.
*/
bp->b_flags &= ~B_KVAALLOC;
KASSERT(bp->b_kvaalloc != 0, ("kvaalloc == 0"));
bp->b_kvabase = bp->b_kvaalloc;
atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
goto has_addr;
}
/*
* Calculate the amount of the address space we would reserve
* if the buffer was mapped.
*/
bsize = vn_isdisk(bp->b_vp, NULL) ? DEV_BSIZE : bp->b_bufobj->bo_bsize;
KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
offset = blkno * bsize;
maxsize = size + (offset & PAGE_MASK);
maxsize = imax(maxsize, bsize);
mapping_loop:
if (allocbufkva(bp, maxsize, gbflags)) {
/*
* Request defragmentation. getnewbuf() returns us the
* allocated space by the scratch buffer KVA.
*/
scratch_bp = getnewbuf(bp->b_vp, 0, 0, size, maxsize, gbflags |
(GB_UNMAPPED | GB_KVAALLOC));
if (scratch_bp == NULL) {
if ((gbflags & GB_NOWAIT_BD) != 0) {
/*
* XXXKIB: defragmentation cannot
* succeed, not sure what else to do.
*/
panic("GB_NOWAIT_BD and B_UNMAPPED %p", bp);
}
atomic_add_int(&mappingrestarts, 1);
goto mapping_loop;
}
KASSERT((scratch_bp->b_flags & B_KVAALLOC) != 0,
("scratch bp !B_KVAALLOC %p", scratch_bp));
setbufkva(bp, (vm_offset_t)scratch_bp->b_kvaalloc,
scratch_bp->b_kvasize, gbflags);
/* Get rid of the scratch buffer. */
scratch_bp->b_kvasize = 0;
scratch_bp->b_flags |= B_INVAL;
scratch_bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
brelse(scratch_bp);
}
if (!need_mapping)
return;
has_addr:
bp->b_saveaddr = bp->b_kvabase;
bp->b_data = bp->b_saveaddr; /* b_offset is handled by bpmap_qenter */
bp->b_flags &= ~B_UNMAPPED;
BUF_CHECK_MAPPED(bp);
bpmap_qenter(bp);
}
/*
* 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 bsize, error, maxsize, vmio;
off_t offset;
CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size);
KASSERT((flags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_KVAALLOC,
("GB_KVAALLOC only makes sense with GB_UNMAPPED"));
ASSERT_VOP_LOCKED(vp, "getblk");
if (size > MAXBSIZE)
panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE);
if (!unmapped_buf_allowed)
flags &= ~(GB_UNMAPPED | GB_KVAALLOC);
bo = &vp->v_bufobj;
loop:
BO_RLOCK(bo);
bp = gbincore(bo, blkno);
if (bp != NULL) {
int lockflags;
/*
* Buffer is in-core. If the buffer is not busy nor managed,
* 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_LOCKPTR(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);
/* If recursed, assume caller knows the rules. */
else if (BUF_LOCKRECURSED(bp))
goto end;
/*
* 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;
if (bp->b_flags & B_MANAGED)
MPASS(bp->b_qindex == QUEUE_NONE);
else
bremfree(bp);
/*
* check for size inconsistencies 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;
}
}
/*
* Handle the case of unmapped buffer which should
* become mapped, or the buffer for which KVA
* reservation is requested.
*/
bp_unmapped_get_kva(bp, blkno, size, flags);
/*
* 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 {
/*
* 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_RUNLOCK(bo);
/*
* If the user does not want us to create the buffer, bail out
* here.
*/
if (flags & GB_NOCREAT)
return NULL;
if (numfreebuffers == 0 && TD_IS_IDLETHREAD(curthread))
return NULL;
bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize;
KASSERT(bsize != 0, ("bsize == 0, check bo->bo_bsize"));
offset = blkno * bsize;
vmio = vp->v_object != NULL;
if (vmio) {
maxsize = size + (offset & PAGE_MASK);
} else {
maxsize = size;
/* Do not allow non-VMIO notmapped buffers. */
flags &= ~GB_UNMAPPED;
}
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;
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));
BUF_CHECK_MAPPED(bp);
}
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);
end:
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, newbsize);
} 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;
if ((bp->b_flags & B_UNMAPPED) == 0) {
BUF_CHECK_MAPPED(bp);
pmap_qremove((vm_offset_t)trunc_page(
(vm_offset_t)bp->b_data) +
(desiredpages << PAGE_SHIFT),
(bp->b_npages - desiredpages));
} else
BUF_CHECK_UNMAPPED(bp);
VM_OBJECT_WLOCK(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,
"biodep"))
continue;
bp->b_pages[i] = NULL;
vm_page_lock(m);
vm_page_unwire(m, PQ_INACTIVE);
vm_page_unlock(m);
}
VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
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_WLOCK(obj);
while (bp->b_npages < desiredpages) {
vm_page_t m;
/*
* We must allocate system pages since blocking
* here could interfere with paging I/O, no
* matter which process we are.
*
* Only exclusive busy can be tested here.
* Blocking on shared busy might lead to
* deadlocks once allocbuf() is called after
* pages are vfs_busy_pages().
*/
m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) +
bp->b_npages, VM_ALLOC_NOBUSY |
VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
VM_ALLOC_IGN_SBUSY |
VM_ALLOC_COUNT(desiredpages - bp->b_npages));
if (m->valid == 0)
bp->b_flags &= ~B_CACHE;
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_WUNLOCK(obj);
/*
* Step 3, fixup the KVM pmap.
*/
if ((bp->b_flags & B_UNMAPPED) == 0)
bpmap_qenter(bp);
else
BUF_CHECK_UNMAPPED(bp);
}
}
if (newbsize < bp->b_bufsize)
bufspacewakeup();
bp->b_bufsize = newbsize; /* actual buffer allocation */
bp->b_bcount = size; /* requested buffer size */
return 1;
}
extern int inflight_transient_maps;
void
biodone(struct bio *bp)
{
struct mtx *mtxp;
void (*done)(struct bio *);
vm_offset_t start, end;
if ((bp->bio_flags & BIO_TRANSIENT_MAPPING) != 0) {
bp->bio_flags &= ~BIO_TRANSIENT_MAPPING;
bp->bio_flags |= BIO_UNMAPPED;
start = trunc_page((vm_offset_t)bp->bio_data);
end = round_page((vm_offset_t)bp->bio_data + bp->bio_length);
pmap_qremove(start, OFF_TO_IDX(end - start));
vmem_free(transient_arena, start, end - start);
atomic_add_int(&inflight_transient_maps, -1);
}
done = bp->bio_done;
if (done == NULL) {
mtxp = mtx_pool_find(mtxpool_sleep, bp);
mtx_lock(mtxp);
bp->bio_flags |= BIO_DONE;
wakeup(bp);
mtx_unlock(mtxp);
} else {
bp->bio_flags |= BIO_DONE;
done(bp);
}
}
/*
* Wait for a BIO to finish.
*/
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, 0);
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 = bip->bio_resid;
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;
int ref;
KASSERT(dev->si_refcount > 0,
("dev_strategy on un-referenced struct cdev *(%s) %p",
devtoname(dev), dev));
csw = dev_refthread(dev, &ref);
dev_strategy_csw(dev, csw, bp);
dev_relthread(dev, ref);
}
void
dev_strategy_csw(struct cdev *dev, struct cdevsw *csw, struct buf *bp)
{
struct bio *bip;
KASSERT(bp->b_iocmd == BIO_READ || bp->b_iocmd == BIO_WRITE,
("b_iocmd botch"));
KASSERT(((dev->si_flags & SI_ETERNAL) != 0 && csw != NULL) ||
dev->si_threadcount > 0,
("dev_strategy_csw threadcount cdev *(%s) %p", devtoname(dev),
dev));
if (csw == NULL) {
bp->b_error = ENXIO;
bp->b_ioflags = BIO_ERROR;
bufdone(bp);
return;
}
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 */
bdata2bio(bp, bip);
bip->bio_done = bufdonebio;
bip->bio_caller2 = bp;
bip->bio_dev = dev;
(*csw->d_strategy)(bip);
}
/*
* 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) {
vm_ooffset_t foff;
vm_page_t m;
vm_object_t obj;
struct vnode *vp;
int bogus, i, iosize;
obj = bp->b_bufobj->bo_object;
KASSERT(obj->paging_in_progress >= bp->b_npages,
("biodone_finish: paging in progress(%d) < b_npages(%d)",
obj->paging_in_progress, bp->b_npages));
vp = bp->b_vp;
KASSERT(vp->v_holdcnt > 0,
("biodone_finish: vnode %p has zero hold count", vp));
KASSERT(vp->v_object != NULL,
("biodone_finish: vnode %p has no vm_object", vp));
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("biodone_finish: bp %p has no buffer offset", bp));
/*
* 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;
}
bogus = 0;
VM_OBJECT_WLOCK(obj);
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) {
bogus = bogusflag = 1;
m = vm_page_lookup(obj, OFF_TO_IDX(foff));
if (m == NULL)
panic("biodone: page disappeared!");
bp->b_pages[i] = m;
}
KASSERT(OFF_TO_IDX(foff) == m->pindex,
("biodone_finish: foff(%jd)/pindex(%ju) mismatch",
(intmax_t)foff, (uintmax_t)m->pindex));
/*
* 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);
}
vm_page_sunbusy(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_WUNLOCK(obj);
if (bogus && (bp->b_flags & B_UNMAPPED) == 0) {
BUF_CHECK_MAPPED(bp);
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
}
/*
* 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_WLOCK(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;
if ((bp->b_flags & B_UNMAPPED) == 0) {
BUF_CHECK_MAPPED(bp);
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
} else
BUF_CHECK_UNMAPPED(bp);
}
vm_object_pip_subtract(obj, 1);
vm_page_sunbusy(m);
}
vm_object_pip_wakeupn(obj, 0);
VM_OBJECT_WUNLOCK(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_range(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;
/*
* 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)
);
}
}
/*
* Ensure that all buffer pages are not exclusive busied. If any page is
* exclusive busy, drain it.
*/
void
vfs_drain_busy_pages(struct buf *bp)
{
vm_page_t m;
int i, last_busied;
VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object);
last_busied = 0;
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (vm_page_xbusied(m)) {
for (; last_busied < i; last_busied++)
vm_page_sbusy(bp->b_pages[last_busied]);
while (vm_page_xbusied(m)) {
vm_page_lock(m);
VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
vm_page_busy_sleep(m, "vbpage");
VM_OBJECT_WLOCK(bp->b_bufobj->bo_object);
}
}
}
for (i = 0; i < last_busied; i++)
vm_page_sunbusy(bp->b_pages[i]);
}
/*
* 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 exclusive 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_WLOCK(obj);
vfs_drain_busy_pages(bp);
if (bp->b_bufsize != 0)
vfs_setdirty_locked_object(bp);
bogus = 0;
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if ((bp->b_flags & B_CLUSTER) == 0) {
vm_object_pip_add(obj, 1);
vm_page_sbusy(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;
}
VM_OBJECT_WUNLOCK(obj);
if (bogus && (bp->b_flags & B_UNMAPPED) == 0) {
BUF_CHECK_MAPPED(bp);
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
}
/*
* 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_WLOCK(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_range(m, base & PAGE_MASK, n);
base += n;
size -= n;
n = PAGE_SIZE;
}
VM_OBJECT_WUNLOCK(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, sa, ea, slide;
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_WLOCK(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_ASSERT_WLOCKED(bp->b_pages[0]->object);
if ((bp->b_pages[0]->valid & mask) == mask)
goto unlock;
if ((bp->b_pages[0]->valid & mask) == 0) {
pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize);
bp->b_pages[0]->valid |= mask;
goto unlock;
}
}
sa = bp->b_offset & PAGE_MASK;
slide = 0;
for (i = 0; i < bp->b_npages; i++, sa = 0) {
slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize);
ea = slide & PAGE_MASK;
if (ea == 0)
ea = PAGE_SIZE;
if (bp->b_pages[i] == bogus_page)
continue;
j = sa / DEV_BSIZE;
mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j;
VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object);
if ((bp->b_pages[i]->valid & mask) == mask)
continue;
if ((bp->b_pages[i]->valid & mask) == 0)
pmap_zero_page_area(bp->b_pages[i], sa, ea - sa);
else {
for (; sa < ea; sa += DEV_BSIZE, j++) {
if ((bp->b_pages[i]->valid & (1 << j)) == 0) {
pmap_zero_page_area(bp->b_pages[i],
sa, DEV_BSIZE);
}
}
}
bp->b_pages[i]->valid |= mask;
}
unlock:
VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object);
bp->b_resid = 0;
}
void
vfs_bio_bzero_buf(struct buf *bp, int base, int size)
{
vm_page_t m;
int i, n;
if ((bp->b_flags & B_UNMAPPED) == 0) {
BUF_CHECK_MAPPED(bp);
bzero(bp->b_data + base, size);
} else {
BUF_CHECK_UNMAPPED(bp);
n = PAGE_SIZE - (base & PAGE_MASK);
for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) {
m = bp->b_pages[i];
if (n > size)
n = size;
pmap_zero_page_area(m, base & PAGE_MASK, n);
base += n;
size -= n;
n = PAGE_SIZE;
}
}
}
/*
* 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;
BUF_CHECK_MAPPED(bp);
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, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ |
VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
if (p == NULL) {
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, int newbsize)
{
vm_offset_t from;
vm_page_t p;
int index, newnpages;
BUF_CHECK_MAPPED(bp);
from = round_page((vm_offset_t)bp->b_data + newbsize);
newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT;
if (bp->b_npages > newnpages)
pmap_qremove(from, bp->b_npages - newnpages);
for (index = newnpages; index < bp->b_npages; index++) {
p = bp->b_pages[index];
bp->b_pages[index] = NULL;
if (vm_page_sbusied(p))
printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n",
(intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno);
p->wire_count--;
vm_page_free(p);
atomic_subtract_int(&vm_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, int mapbuf)
{
caddr_t kva;
vm_prot_t prot;
int pidx;
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 */
if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map,
(vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages,
btoc(MAXPHYS))) < 0)
return (-1);
bp->b_npages = pidx;
if (mapbuf || !unmapped_buf_allowed) {
pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx);
kva = bp->b_saveaddr;
bp->b_saveaddr = bp->b_data;
bp->b_data = kva + (((vm_offset_t)bp->b_data) & PAGE_MASK);
bp->b_flags &= ~B_UNMAPPED;
} else {
bp->b_flags |= B_UNMAPPED;
bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
bp->b_saveaddr = bp->b_data;
bp->b_data = unmapped_buf;
}
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 npages;
npages = bp->b_npages;
if (bp->b_flags & B_UNMAPPED)
bp->b_flags &= ~B_UNMAPPED;
else
pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
vm_page_unhold_pages(bp->b_pages, npages);
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_WLOCKED(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_WLOCKED(bo);
error = 0;
while (bo->bo_numoutput) {
bo->bo_flag |= BO_WWAIT;
error = msleep(&bo->bo_numoutput, BO_LOCKPTR(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);
}
/*
* Set bio_data or bio_ma for struct bio from the struct buf.
*/
void
bdata2bio(struct buf *bp, struct bio *bip)
{
if ((bp->b_flags & B_UNMAPPED) != 0) {
KASSERT(unmapped_buf_allowed, ("unmapped"));
bip->bio_ma = bp->b_pages;
bip->bio_ma_n = bp->b_npages;
bip->bio_data = unmapped_buf;
bip->bio_ma_offset = (vm_offset_t)bp->b_offset & PAGE_MASK;
bip->bio_flags |= BIO_UNMAPPED;
KASSERT(round_page(bip->bio_ma_offset + bip->bio_length) /
PAGE_SIZE == bp->b_npages,
("Buffer %p too short: %d %lld %d", bp, bip->bio_ma_offset,
(long long)bip->bio_length, bip->bio_ma_n));
} else {
bip->bio_data = bp->b_data;
bip->bio_ma = NULL;
}
}
#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, b_xflags=0x%b, b_vflags=0x%b\n",
(u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags,
PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS);
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_lblkno = %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,
(intmax_t)bp->b_lblkno, 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(" ");
BUF_LOCKPRINTINFO(bp);
}
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");
}
}
DB_COMMAND(countfreebufs, db_coundfreebufs)
{
struct buf *bp;
int i, used = 0, nfree = 0;
if (have_addr) {
db_printf("usage: countfreebufs\n");
return;
}
for (i = 0; i < nbuf; i++) {
bp = &buf[i];
if ((bp->b_flags & B_INFREECNT) != 0)
nfree++;
else
used++;
}
db_printf("Counted %d free, %d used (%d tot)\n", nfree, used,
nfree + used);
db_printf("numfreebuffers is %d\n", numfreebuffers);
}
#endif /* DDB */
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