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freebsd-skq/sys/kern/vfs_bio.c
Mark Johnston 0649caae32 Let DDB's buf printer handle NULL pointers in the buf page array. 
A buf's b_pages and b_npages fields may be inconsistent after a panic.
For instance, vfs_vmio_invalidate() sets b_npages to zero only after all
pages are unwired and their page array entries are cleared.

MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
2016-07-14 18:49:05 +00:00

4802 lines
123 KiB
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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/racct.h>
#include <sys/resourcevar.h>
#include <sys/rwlock.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/vmem.h>
#include <sys/vmmeter.h>
#include <sys/vnode.h>
#include <sys/watchdog.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 <vm/swap_pager.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,
};
static struct buf *buf; /* buffer header pool */
extern struct buf *swbuf; /* Swap buffer header pool. */
caddr_t unmapped_buf;
/* Used below and for softdep flushing threads in ufs/ffs/ffs_softdep.c */
struct proc *bufdaemonproc;
struct proc *bufspacedaemonproc;
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_invalidate(struct buf *bp);
static void vfs_vmio_truncate(struct buf *bp, int npages);
static void vfs_vmio_extend(struct buf *bp, int npages, int size);
static int vfs_bio_clcheck(struct vnode *vp, int size,
daddr_t lblkno, daddr_t blkno);
static int buf_flush(struct vnode *vp, int);
static int buf_recycle(bool);
static int buf_scan(bool);
static int flushbufqueues(struct vnode *, 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);
static void bufkva_reclaim(vmem_t *, int);
static void bufkva_free(struct buf *);
static int buf_import(void *, void **, int, int);
static void buf_release(void *, void **, int);
#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,
"Physical memory used for buffers");
#endif
static long bufkvaspace;
SYSCTL_LONG(_vfs, OID_AUTO, bufkvaspace, CTLFLAG_RD, &bufkvaspace, 0,
"Kernel virtual memory used for buffers");
static long maxbufspace;
SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RW, &maxbufspace, 0,
"Maximum allowed value of bufspace (including metadata)");
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_RW, &lobufspace, 0,
"Minimum amount of buffers we want to have");
long hibufspace;
SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RW, &hibufspace, 0,
"Maximum allowed value of bufspace (excluding metadata)");
long bufspacethresh;
SYSCTL_LONG(_vfs, OID_AUTO, bufspacethresh, CTLFLAG_RW, &bufspacethresh,
0, "Bufspace consumed before waking the daemon to free some");
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,
"Target number of free buffers");
static int hifreebuffers;
SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0,
"Threshold for clean buffer recycling");
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 acquisition");
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 numbufallocfails;
SYSCTL_INT(_vfs, OID_AUTO, numbufallocfails, CTLFLAG_RW, &numbufallocfails, 0,
"Number of times buffer allocations failed");
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");
/*
* 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/wakeup point for the bufspace daemon.
*/
static int bufspace_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(), bufspace_wakeup(), bwillwrite(),
* getnewbuf(), and getblk().
*/
static volatile int needsbuffer;
/*
* Synchronization for bwillwrite() waiters.
*/
static int bdirtywait;
/*
* Definitions for the buffer free lists.
*/
#define QUEUE_NONE 0 /* on no queue */
#define QUEUE_EMPTY 1 /* empty buffer headers */
#define QUEUE_DIRTY 2 /* B_DELWRI buffers */
#define QUEUE_CLEAN 3 /* non-B_DELWRI buffers */
#define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */
/* Maximum number of clean buffer queues. */
#define CLEAN_QUEUES 16
/* Configured number of clean queues. */
static int clean_queues;
/* Maximum number of buffer queues. */
#define BUFFER_QUEUES (QUEUE_CLEAN + CLEAN_QUEUES)
/* 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
/*
* Lock for each bufqueue
*/
static struct mtx_padalign bqlocks[BUFFER_QUEUES];
/*
* per-cpu empty buffer cache.
*/
uma_zone_t buf_zone;
/*
* Single global constant for BUF_WMESG, to avoid getting multiple references.
* buf_wmesg is referred from macros.
*/
const char *buf_wmesg = BUF_WMESG;
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
static int
bqcleanq(void)
{
static int nextq;
return ((atomic_fetchadd_int(&nextq, 1) % clean_queues) + QUEUE_CLEAN);
}
static int
bqisclean(int qindex)
{
return (qindex >= QUEUE_CLEAN && qindex < QUEUE_CLEAN + CLEAN_QUEUES);
}
/*
* bqlock:
*
* Return the appropriate queue lock based on the index.
*/
static inline struct mtx *
bqlock(int qindex)
{
return (struct mtx *)&bqlocks[qindex];
}
/*
* 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();
}
/*
* bufspace_wakeup:
*
* 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 void
bufspace_wakeup(void)
{
/*
* If someone is waiting for bufspace, wake them up.
*
* Since needsbuffer is set prior to doing an additional queue
* scan it is safe to check for the flag prior to acquiring the
* lock. The thread that is preparing to scan again before
* blocking would discover the buf we released.
*/
if (needsbuffer) {
rw_rlock(&nblock);
if (atomic_cmpset_int(&needsbuffer, 1, 0) == 1)
wakeup(__DEVOLATILE(void *, &needsbuffer));
rw_runlock(&nblock);
}
}
/*
* bufspace_daemonwakeup:
*
* Wakeup the daemon responsible for freeing clean bufs.
*/
static void
bufspace_daemonwakeup(void)
{
rw_rlock(&nblock);
if (bufspace_request == 0) {
bufspace_request = 1;
wakeup(&bufspace_request);
}
rw_runlock(&nblock);
}
/*
* bufspace_adjust:
*
* Adjust the reported bufspace for a KVA managed buffer, possibly
* waking any waiters.
*/
static void
bufspace_adjust(struct buf *bp, int bufsize)
{
long space;
int diff;
KASSERT((bp->b_flags & B_MALLOC) == 0,
("bufspace_adjust: malloc buf %p", bp));
diff = bufsize - bp->b_bufsize;
if (diff < 0) {
atomic_subtract_long(&bufspace, -diff);
bufspace_wakeup();
} else {
space = atomic_fetchadd_long(&bufspace, diff);
/* Wake up the daemon on the transition. */
if (space < bufspacethresh && space + diff >= bufspacethresh)
bufspace_daemonwakeup();
}
bp->b_bufsize = bufsize;
}
/*
* bufspace_reserve:
*
* Reserve bufspace before calling allocbuf(). metadata has a
* different space limit than data.
*/
static int
bufspace_reserve(int size, bool metadata)
{
long limit;
long space;
if (metadata)
limit = maxbufspace;
else
limit = hibufspace;
do {
space = bufspace;
if (space + size > limit)
return (ENOSPC);
} while (atomic_cmpset_long(&bufspace, space, space + size) == 0);
/* Wake up the daemon on the transition. */
if (space < bufspacethresh && space + size >= bufspacethresh)
bufspace_daemonwakeup();
return (0);
}
/*
* bufspace_release:
*
* Release reserved bufspace after bufspace_adjust() has consumed it.
*/
static void
bufspace_release(int size)
{
atomic_subtract_long(&bufspace, size);
bufspace_wakeup();
}
/*
* bufspace_wait:
*
* Wait for bufspace, acting as the buf daemon if a locked vnode is
* supplied. needsbuffer must be set in a safe fashion prior to
* polling for space. The operation must be re-tried on return.
*/
static void
bufspace_wait(struct vnode *vp, int gbflags, int slpflag, int slptimeo)
{
struct thread *td;
int error, fl, norunbuf;
if ((gbflags & GB_NOWAIT_BD) != 0)
return;
td = curthread;
rw_wlock(&nblock);
while (needsbuffer != 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.
*/
norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) |
(td->td_pflags & TDP_NORUNNINGBUF);
/*
* Play bufdaemon. The getnewbuf() function
* may be called while the thread owns lock
* for another dirty buffer for the same
* vnode, which makes it impossible to use
* VOP_FSYNC() there, due to the buffer lock
* recursion.
*/
td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF;
fl = buf_flush(vp, flushbufqtarget);
td->td_pflags &= norunbuf;
rw_wlock(&nblock);
if (fl != 0)
continue;
if (needsbuffer == 0)
break;
}
error = rw_sleep(__DEVOLATILE(void *, &needsbuffer), &nblock,
(PRIBIO + 4) | slpflag, "newbuf", slptimeo);
if (error != 0)
break;
}
rw_wunlock(&nblock);
}
/*
* bufspace_daemon:
*
* buffer space management daemon. Tries to maintain some marginal
* amount of free buffer space so that requesting processes neither
* block nor work to reclaim buffers.
*/
static void
bufspace_daemon(void)
{
for (;;) {
kproc_suspend_check(bufspacedaemonproc);
/*
* Free buffers from the clean queue until we meet our
* targets.
*
* Theory of operation: The buffer cache is most efficient
* when some free buffer headers and space are always
* available to getnewbuf(). This daemon attempts to prevent
* the excessive blocking and synchronization associated
* with shortfall. It goes through three phases according
* demand:
*
* 1) The daemon wakes up voluntarily once per-second
* during idle periods when the counters are below
* the wakeup thresholds (bufspacethresh, lofreebuffers).
*
* 2) The daemon wakes up as we cross the thresholds
* ahead of any potential blocking. This may bounce
* slightly according to the rate of consumption and
* release.
*
* 3) The daemon and consumers are starved for working
* clean buffers. This is the 'bufspace' sleep below
* which will inefficiently trade bufs with bqrelse
* until we return to condition 2.
*/
while (bufspace > lobufspace ||
numfreebuffers < hifreebuffers) {
if (buf_recycle(false) != 0) {
atomic_set_int(&needsbuffer, 1);
if (buf_recycle(false) != 0) {
rw_wlock(&nblock);
if (needsbuffer)
rw_sleep(__DEVOLATILE(void *,
&needsbuffer), &nblock,
PRIBIO|PDROP, "bufspace",
hz/10);
else
rw_wunlock(&nblock);
}
}
maybe_yield();
}
/*
* Re-check our limits under the exclusive nblock.
*/
rw_wlock(&nblock);
if (bufspace < bufspacethresh &&
numfreebuffers > lofreebuffers) {
bufspace_request = 0;
rw_sleep(&bufspace_request, &nblock, PRIBIO|PDROP,
"-", hz);
} else
rw_wunlock(&nblock);
}
}
static struct kproc_desc bufspace_kp = {
"bufspacedaemon",
bufspace_daemon,
&bufspacedaemonproc
};
SYSINIT(bufspacedaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start,
&bufspace_kp);
/*
* bufmallocadjust:
*
* Adjust the reported bufspace for a malloc managed buffer, possibly
* waking any waiters.
*/
static void
bufmallocadjust(struct buf *bp, int bufsize)
{
int diff;
KASSERT((bp->b_flags & B_MALLOC) != 0,
("bufmallocadjust: non-malloc buf %p", bp));
diff = bufsize - bp->b_bufsize;
if (diff < 0)
atomic_subtract_long(&bufmallocspace, -diff);
else
atomic_add_long(&bufmallocspace, diff);
bp->b_bufsize = bufsize;
}
/*
* 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();
}
/*
* 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;
/*
* Artificially 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;
CTASSERT(MAXBCACHEBUF >= MAXBSIZE);
mtx_init(&bqlocks[QUEUE_DIRTY], "bufq dirty lock", NULL, MTX_DEF);
mtx_init(&bqlocks[QUEUE_EMPTY], "bufq empty lock", NULL, MTX_DEF);
for (i = QUEUE_CLEAN; i < QUEUE_CLEAN + CLEAN_QUEUES; i++)
mtx_init(&bqlocks[i], "bufq clean 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]);
unmapped_buf = (caddr_t)kva_alloc(MAXPHYS);
/* 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;
bp->b_rcred = NOCRED;
bp->b_wcred = NOCRED;
bp->b_qindex = QUEUE_EMPTY;
bp->b_xflags = 0;
bp->b_data = bp->b_kvabase = unmapped_buf;
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 metadata. hibufspace is the nominal maximum
* used by most other requests. The differential is required to
* ensure that metadata deadlocks don't occur.
*
* maxbufspace is based on BKVASIZE. Allocating buffers larger then
* this may result in KVM fragmentation which is not handled optimally
* by the system. XXX This is less true with vmem. We could use
* PAGE_SIZE.
*/
maxbufspace = (long)nbuf * BKVASIZE;
hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBCACHEBUF * 10);
lobufspace = (hibufspace / 20) * 19; /* 95% */
bufspacethresh = lobufspace + (hibufspace - lobufspace) / 2;
/*
* 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, MAXBCACHEBUF),
16 * 1024 * 1024), 1024 * 1024);
lorunningspace = roundup((hirunningspace * 2) / 3, MAXBCACHEBUF);
/*
* 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 occurring 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;
/*
* lofreebuffers should be sufficient to avoid stalling waiting on
* buf headers under heavy utilization. The bufs in per-cpu caches
* are counted as free but will be unavailable to threads executing
* on other cpus.
*
* hifreebuffers is the free target for the bufspace daemon. This
* should be set appropriately to limit work per-iteration.
*/
lofreebuffers = MIN((nbuf / 25) + (20 * mp_ncpus), 128 * mp_ncpus);
hifreebuffers = (3 * lofreebuffers) / 2;
numfreebuffers = nbuf;
bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ |
VM_ALLOC_NORMAL | VM_ALLOC_WIRED);
/* Setup the kva and free list allocators. */
vmem_set_reclaim(buffer_arena, bufkva_reclaim);
buf_zone = uma_zcache_create("buf free cache", sizeof(struct buf),
NULL, NULL, NULL, NULL, buf_import, buf_release, NULL, 0);
/*
* Size the clean queue according to the amount of buffer space.
* One queue per-256mb up to the max. More queues gives better
* concurrency but less accurate LRU.
*/
clean_queues = MIN(howmany(maxbufspace, 256*1024*1024), CLEAN_QUEUES);
}
#ifdef INVARIANTS
static inline void
vfs_buf_check_mapped(struct buf *bp)
{
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));
KASSERT(bp->b_data < unmapped_buf || bp->b_data >= unmapped_buf +
MAXPHYS, ("b_data + b_offset unmapped %p", bp));
}
static inline void
vfs_buf_check_unmapped(struct buf *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 int
isbufbusy(struct buf *bp)
{
if (((bp->b_flags & B_INVAL) == 0 && BUF_ISLOCKED(bp)) ||
((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI))
return (1);
return (0);
}
/*
* Shutdown the system cleanly to prepare for reboot, halt, or power off.
*/
void
bufshutdown(int show_busybufs)
{
static int first_buf_printf = 1;
struct buf *bp;
int iter, nbusy, pbusy;
#ifndef PREEMPTION
int subiter;
#endif
/*
* Sync filesystems for shutdown
*/
wdog_kern_pat(WD_LASTVAL);
sys_sync(curthread, NULL);
/*
* With soft updates, some buffers that are
* written will be remarked as dirty until other
* buffers are written.
*/
for (iter = pbusy = 0; iter < 20; iter++) {
nbusy = 0;
for (bp = &buf[nbuf]; --bp >= buf; )
if (isbufbusy(bp))
nbusy++;
if (nbusy == 0) {
if (first_buf_printf)
printf("All buffers synced.");
break;
}
if (first_buf_printf) {
printf("Syncing disks, buffers remaining... ");
first_buf_printf = 0;
}
printf("%d ", nbusy);
if (nbusy < pbusy)
iter = 0;
pbusy = nbusy;
wdog_kern_pat(WD_LASTVAL);
sys_sync(curthread, NULL);
#ifdef PREEMPTION
/*
* Drop Giant and spin for a while to allow
* interrupt threads to run.
*/
DROP_GIANT();
DELAY(50000 * iter);
PICKUP_GIANT();
#else
/*
* Drop Giant and context switch several times to
* allow interrupt threads to run.
*/
DROP_GIANT();
for (subiter = 0; subiter < 50 * iter; subiter++) {
thread_lock(curthread);
mi_switch(SW_VOL, NULL);
thread_unlock(curthread);
DELAY(1000);
}
PICKUP_GIANT();
#endif
}
printf("\n");
/*
* Count only busy local buffers to prevent forcing
* a fsck if we're just a client of a wedged NFS server
*/
nbusy = 0;
for (bp = &buf[nbuf]; --bp >= buf; ) {
if (isbufbusy(bp)) {
#if 0
/* XXX: This is bogus. We should probably have a BO_REMOTE flag instead */
if (bp->b_dev == NULL) {
TAILQ_REMOVE(&mountlist,
bp->b_vp->v_mount, mnt_list);
continue;
}
#endif
nbusy++;
if (show_busybufs > 0) {
printf(
"%d: buf:%p, vnode:%p, flags:%0x, blkno:%jd, lblkno:%jd, buflock:",
nbusy, bp, bp->b_vp, bp->b_flags,
(intmax_t)bp->b_blkno,
(intmax_t)bp->b_lblkno);
BUF_LOCKPRINTINFO(bp);
if (show_busybufs > 1)
vn_printf(bp->b_vp,
"vnode content: ");
}
}
}
if (nbusy) {
/*
* Failed to sync all blocks. Indicate this and don't
* unmount filesystems (thus forcing an fsck on reboot).
*/
printf("Giving up on %d buffers\n", nbusy);
DELAY(5000000); /* 5 seconds */
} else {
if (!first_buf_printf)
printf("Final sync complete\n");
/*
* Unmount filesystems
*/
if (panicstr == NULL)
vfs_unmountall();
}
swapoff_all();
DELAY(100000); /* wait for console output to finish */
}
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));
}
/*
* binsfree:
*
* Insert the buffer into the appropriate free list.
*/
static void
binsfree(struct buf *bp, int qindex)
{
struct mtx *olock, *nlock;
if (qindex != QUEUE_EMPTY) {
BUF_ASSERT_XLOCKED(bp);
}
/*
* Stick to the same clean queue for the lifetime of the buf to
* limit locking below. Otherwise pick ont sequentially.
*/
if (qindex == QUEUE_CLEAN) {
if (bqisclean(bp->b_qindex))
qindex = bp->b_qindex;
else
qindex = bqcleanq();
}
/*
* Handle delayed bremfree() processing.
*/
nlock = bqlock(qindex);
if (bp->b_flags & B_REMFREE) {
olock = bqlock(bp->b_qindex);
mtx_lock(olock);
bremfreel(bp);
if (olock != nlock) {
mtx_unlock(olock);
mtx_lock(nlock);
}
} else
mtx_lock(nlock);
if (bp->b_qindex != QUEUE_NONE)
panic("binsfree: free buffer onto another queue???");
bp->b_qindex = qindex;
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);
}
/*
* buf_free:
*
* Free a buffer to the buf zone once it no longer has valid contents.
*/
static void
buf_free(struct buf *bp)
{
if (bp->b_flags & B_REMFREE)
bremfreef(bp);
if (bp->b_vflags & BV_BKGRDINPROG)
panic("losing buffer 1");
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);
bufkva_free(bp);
BUF_UNLOCK(bp);
uma_zfree(buf_zone, bp);
atomic_add_int(&numfreebuffers, 1);
bufspace_wakeup();
}
/*
* buf_import:
*
* Import bufs into the uma cache from the buf list. The system still
* expects a static array of bufs and much of the synchronization
* around bufs assumes type stable storage. As a result, UMA is used
* only as a per-cpu cache of bufs still maintained on a global list.
*/
static int
buf_import(void *arg, void **store, int cnt, int flags)
{
struct buf *bp;
int i;
mtx_lock(&bqlocks[QUEUE_EMPTY]);
for (i = 0; i < cnt; i++) {
bp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]);
if (bp == NULL)
break;
bremfreel(bp);
store[i] = bp;
}
mtx_unlock(&bqlocks[QUEUE_EMPTY]);
return (i);
}
/*
* buf_release:
*
* Release bufs from the uma cache back to the buffer queues.
*/
static void
buf_release(void *arg, void **store, int cnt)
{
int i;
for (i = 0; i < cnt; i++)
binsfree(store[i], QUEUE_EMPTY);
}
/*
* buf_alloc:
*
* Allocate an empty buffer header.
*/
static struct buf *
buf_alloc(void)
{
struct buf *bp;
bp = uma_zalloc(buf_zone, M_NOWAIT);
if (bp == NULL) {
bufspace_daemonwakeup();
atomic_add_int(&numbufallocfails, 1);
return (NULL);
}
/*
* Wake-up the bufspace daemon on transition.
*/
if (atomic_fetchadd_int(&numfreebuffers, -1) == lofreebuffers)
bufspace_daemonwakeup();
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
panic("getnewbuf_empty: Locked buf %p on free queue.", bp);
KASSERT(bp->b_vp == NULL,
("bp: %p still has vnode %p.", bp, bp->b_vp));
KASSERT((bp->b_flags & (B_DELWRI | B_NOREUSE)) == 0,
("invalid buffer %p flags %#x", bp, bp->b_flags));
KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0,
("bp: %p still on a buffer list. xflags %X", bp, bp->b_xflags));
KASSERT(bp->b_npages == 0,
("bp: %p still has %d vm pages\n", bp, bp->b_npages));
KASSERT(bp->b_kvasize == 0, ("bp: %p still has kva\n", bp));
KASSERT(bp->b_bufsize == 0, ("bp: %p still has bufspace\n", bp));
bp->b_flags = 0;
bp->b_ioflags = 0;
bp->b_xflags = 0;
bp->b_vflags = 0;
bp->b_vp = NULL;
bp->b_blkno = bp->b_lblkno = 0;
bp->b_offset = NOOFFSET;
bp->b_iodone = 0;
bp->b_error = 0;
bp->b_resid = 0;
bp->b_bcount = 0;
bp->b_npages = 0;
bp->b_dirtyoff = bp->b_dirtyend = 0;
bp->b_bufobj = NULL;
bp->b_pin_count = 0;
bp->b_data = bp->b_kvabase = unmapped_buf;
bp->b_fsprivate1 = NULL;
bp->b_fsprivate2 = NULL;
bp->b_fsprivate3 = NULL;
LIST_INIT(&bp->b_dep);
return (bp);
}
/*
* buf_qrecycle:
*
* Free a buffer from the given bufqueue. kva controls whether the
* freed buf must own some kva resources. This is used for
* defragmenting.
*/
static int
buf_qrecycle(int qindex, bool kva)
{
struct buf *bp, *nbp;
if (kva)
atomic_add_int(&bufdefragcnt, 1);
nbp = NULL;
mtx_lock(&bqlocks[qindex]);
nbp = TAILQ_FIRST(&bufqueues[qindex]);
/*
* Run scan, possibly freeing data and/or kva mappings on the fly
* depending.
*/
while ((bp = nbp) != NULL) {
/*
* Calculate next bp (we can only use it if we do not
* release the bqlock).
*/
nbp = TAILQ_NEXT(bp, b_freelist);
/*
* If we are defragging then we need a buffer with
* some kva to reclaim.
*/
if (kva && bp->b_kvasize == 0)
continue;
if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0)
continue;
/*
* Skip buffers with background writes in progress.
*/
if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
BUF_UNLOCK(bp);
continue;
}
KASSERT(bp->b_qindex == qindex,
("getnewbuf: inconsistent queue %d bp %p", qindex, bp));
/*
* NOTE: nbp is now entirely invalid. We can only restart
* the scan from this point on.
*/
bremfreel(bp);
mtx_unlock(&bqlocks[qindex]);
/*
* Requeue the background write buffer with error and
* restart the scan.
*/
if ((bp->b_vflags & BV_BKGRDERR) != 0) {
bqrelse(bp);
mtx_lock(&bqlocks[qindex]);
nbp = TAILQ_FIRST(&bufqueues[qindex]);
continue;
}
bp->b_flags |= B_INVAL;
brelse(bp);
return (0);
}
mtx_unlock(&bqlocks[qindex]);
return (ENOBUFS);
}
/*
* buf_recycle:
*
* Iterate through all clean queues until we find a buf to recycle or
* exhaust the search.
*/
static int
buf_recycle(bool kva)
{
int qindex, first_qindex;
qindex = first_qindex = bqcleanq();
do {
if (buf_qrecycle(qindex, kva) == 0)
return (0);
if (++qindex == QUEUE_CLEAN + clean_queues)
qindex = QUEUE_CLEAN;
} while (qindex != first_qindex);
return (ENOBUFS);
}
/*
* buf_scan:
*
* Scan the clean queues looking for a buffer to recycle. needsbuffer
* is set on failure so that the caller may optionally bufspace_wait()
* in a race-free fashion.
*/
static int
buf_scan(bool defrag)
{
int error;
/*
* To avoid heavy synchronization and wakeup races we set
* needsbuffer and re-poll before failing. This ensures that
* no frees can be missed between an unsuccessful poll and
* going to sleep in a synchronized fashion.
*/
if ((error = buf_recycle(defrag)) != 0) {
atomic_set_int(&needsbuffer, 1);
bufspace_daemonwakeup();
error = buf_recycle(defrag);
}
if (error == 0)
atomic_add_int(&getnewbufrestarts, 1);
return (error);
}
/*
* 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;
}
/*
* 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));
if (bp->b_qindex != QUEUE_EMPTY) {
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;
bp->b_flags &= ~B_REMFREE;
}
/*
* bufkva_free:
*
* Free the kva allocation for a buffer.
*
*/
static void
bufkva_free(struct buf *bp)
{
#ifdef INVARIANTS
if (bp->b_kvasize == 0) {
KASSERT(bp->b_kvabase == unmapped_buf &&
bp->b_data == unmapped_buf,
("Leaked KVA space on %p", bp));
} else if (buf_mapped(bp))
BUF_CHECK_MAPPED(bp);
else
BUF_CHECK_UNMAPPED(bp);
#endif
if (bp->b_kvasize == 0)
return;
vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase, bp->b_kvasize);
atomic_subtract_long(&bufkvaspace, bp->b_kvasize);
atomic_add_int(&buffreekvacnt, 1);
bp->b_data = bp->b_kvabase = unmapped_buf;
bp->b_kvasize = 0;
}
/*
* bufkva_alloc:
*
* Allocate the buffer KVA and set b_kvasize and b_kvabase.
*/
static int
bufkva_alloc(struct buf *bp, int maxsize, int gbflags)
{
vm_offset_t addr;
int error;
KASSERT((gbflags & GB_UNMAPPED) == 0 || (gbflags & GB_KVAALLOC) != 0,
("Invalid gbflags 0x%x in %s", gbflags, __func__));
bufkva_free(bp);
addr = 0;
error = vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr);
if (error != 0) {
/*
* Buffer map is too fragmented. Request the caller
* to defragment the map.
*/
return (error);
}
bp->b_kvabase = (caddr_t)addr;
bp->b_kvasize = maxsize;
atomic_add_long(&bufkvaspace, bp->b_kvasize);
if ((gbflags & GB_UNMAPPED) != 0) {
bp->b_data = unmapped_buf;
BUF_CHECK_UNMAPPED(bp);
} else {
bp->b_data = bp->b_kvabase;
BUF_CHECK_MAPPED(bp);
}
return (0);
}
/*
* bufkva_reclaim:
*
* Reclaim buffer kva by freeing buffers holding kva. This is a vmem
* callback that fires to avoid returning failure.
*/
static void
bufkva_reclaim(vmem_t *vmem, int flags)
{
int i;
for (i = 0; i < 5; i++)
if (buf_scan(true) != 0)
break;
return;
}
/*
* 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)) {
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(curproc);
racct_add_buf(curproc, rabp, 0);
PROC_UNLOCK(curproc);
}
#endif /* RACCT */
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.
*
* Always return a NULL buffer pointer (in bpp) when returning an error.
*/
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)) {
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(curproc);
racct_add_buf(curproc, bp, 0);
PROC_UNLOCK(curproc);
}
#endif /* RACCT */
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);
if (rv != 0) {
brelse(bp);
*bpp = NULL;
}
}
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_bufobj->bo_flag & BO_DEAD) != 0) {
bp->b_flags |= B_INVAL | B_RELBUF;
bp->b_flags &= ~B_CACHE;
brelse(bp);
return (ENXIO);
}
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)) {
#ifdef RACCT
if (racct_enable) {
PROC_LOCK(curproc);
racct_add_buf(curproc, bp, 1);
PROC_UNLOCK(curproc);
}
#endif /* RACCT */
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);
}
/*
* 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;
/*
* Many functions erroneously call brelse with a NULL bp under rare
* error conditions. Simply return when called with a NULL bp.
*/
if (bp == NULL)
return;
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));
KASSERT((bp->b_flags & B_VMIO) != 0 || (bp->b_flags & B_NOREUSE) == 0,
("brelse: non-VMIO buffer marked NOREUSE"));
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_vflags & (BV_BKGRDINPROG | BV_BKGRDERR)) == BV_BKGRDERR) {
BO_LOCK(bp->b_bufobj);
bp->b_vflags &= ~BV_BKGRDERR;
BO_UNLOCK(bp->b_bufobj);
bdirty(bp);
}
if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) &&
!(bp->b_flags & B_INVAL)) {
/*
* Failed write, redirty. Must clear BIO_ERROR to prevent
* pages from being scrapped.
*/
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 read 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) {
allocbuf(bp, 0);
if (bp->b_vp)
brelvp(bp);
}
}
/*
* We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_truncate()
* 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_truncate(), even
* if B_DELWRI is set.
*/
if (bp->b_flags & B_DELWRI)
bp->b_flags &= ~B_RELBUF;
/*
* VMIO buffer rundown. It is not very necessary to keep a VMIO buffer
* constituted, not even NFS buffers now. Two flags effect this. If
* B_INVAL, the struct buf is invalidated but the VM object is kept
* around ( i.e. so it is trivial to reconstitute the buffer later ).
*
* If 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_flags & B_NOCACHE ||
(bp->b_ioflags & BIO_ERROR && bp->b_iocmd == BIO_READ)) &&
!(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))) {
vfs_vmio_invalidate(bp);
allocbuf(bp, 0);
}
if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0 ||
(bp->b_flags & (B_DELWRI | B_NOREUSE)) == B_NOREUSE) {
allocbuf(bp, 0);
bp->b_flags &= ~B_NOREUSE;
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) {
buf_free(bp);
return;
}
/* buffers with junk contents */
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);
if (qindex == QUEUE_CLEAN)
bufspace_wakeup();
}
/*
* 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));
qindex = QUEUE_NONE;
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) != 0 || (bp->b_vflags & (BV_BKGRDINPROG |
BV_BKGRDERR)) == BV_BKGRDERR) {
BO_LOCK(bp->b_bufobj);
bp->b_vflags &= ~BV_BKGRDERR;
BO_UNLOCK(bp->b_bufobj);
qindex = QUEUE_DIRTY;
} else {
if ((bp->b_flags & B_DELWRI) == 0 &&
(bp->b_xflags & BX_VNDIRTY))
panic("bqrelse: not dirty");
if ((bp->b_flags & B_NOREUSE) != 0) {
brelse(bp);
return;
}
qindex = QUEUE_CLEAN;
}
binsfree(bp, qindex);
out:
/* unlock */
BUF_UNLOCK(bp);
if (qindex == QUEUE_CLEAN)
bufspace_wakeup();
}
/*
* Complete I/O to a VMIO backed page. Validate the pages as appropriate,
* restore bogus pages.
*/
static void
vfs_vmio_iodone(struct buf *bp)
{
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,
("vfs_vmio_iodone: paging in progress(%d) < b_npages(%d)",
obj->paging_in_progress, bp->b_npages));
vp = bp->b_vp;
KASSERT(vp->v_holdcnt > 0,
("vfs_vmio_iodone: vnode %p has zero hold count", vp));
KASSERT(vp->v_object != NULL,
("vfs_vmio_iodone: vnode %p has no vm_object", vp));
foff = bp->b_offset;
KASSERT(bp->b_offset != NOOFFSET,
("vfs_vmio_iodone: bp %p has no buffer offset", bp));
bogus = 0;
iosize = bp->b_bcount - bp->b_resid;
VM_OBJECT_WLOCK(obj);
for (i = 0; i < bp->b_npages; i++) {
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 = 1;
m = vm_page_lookup(obj, OFF_TO_IDX(foff));
if (m == NULL)
panic("biodone: page disappeared!");
bp->b_pages[i] = m;
} else if ((bp->b_iocmd == BIO_READ) && resid > 0) {
/*
* 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.
*/
KASSERT((m->dirty & vm_page_bits(foff & PAGE_MASK,
resid)) == 0, ("vfs_vmio_iodone: page %p "
"has unexpected dirty bits", m));
vfs_page_set_valid(bp, foff, m);
}
KASSERT(OFF_TO_IDX(foff) == m->pindex,
("vfs_vmio_iodone: foff(%jd)/pindex(%ju) mismatch",
(intmax_t)foff, (uintmax_t)m->pindex));
vm_page_sunbusy(m);
foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK;
iosize -= resid;
}
vm_object_pip_wakeupn(obj, bp->b_npages);
VM_OBJECT_WUNLOCK(obj);
if (bogus && buf_mapped(bp)) {
BUF_CHECK_MAPPED(bp);
pmap_qenter(trunc_page((vm_offset_t)bp->b_data),
bp->b_pages, bp->b_npages);
}
}
/*
* Unwire a page held by a buf and place it on the appropriate vm queue.
*/
static void
vfs_vmio_unwire(struct buf *bp, vm_page_t m)
{
bool freed;
vm_page_lock(m);
if (vm_page_unwire(m, PQ_NONE)) {
/*
* Determine if the page should be freed before adding
* it to the inactive queue.
*/
if (m->valid == 0) {
freed = !vm_page_busied(m);
if (freed)
vm_page_free(m);
} else if ((bp->b_flags & B_DIRECT) != 0)
freed = vm_page_try_to_free(m);
else
freed = false;
if (!freed) {
/*
* If the page is unlikely to be reused, let the
* VM know. Otherwise, maintain LRU page
* ordering and put the page at the tail of the
* inactive queue.
*/
if ((bp->b_flags & B_NOREUSE) != 0)
vm_page_deactivate_noreuse(m);
else
vm_page_deactivate(m);
}
}
vm_page_unlock(m);
}
/*
* Perform page invalidation when a buffer is released. The fully invalid
* pages will be reclaimed later in vfs_vmio_truncate().
*/
static void
vfs_vmio_invalidate(struct buf *bp)
{
vm_object_t obj;
vm_page_t m;
int i, resid, poffset, presid;
if (buf_mapped(bp)) {
BUF_CHECK_MAPPED(bp);
pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages);
} else
BUF_CHECK_UNMAPPED(bp);
/*
* 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
*/
obj = bp->b_bufobj->bo_object;
resid = bp->b_bufsize;
poffset = bp->b_offset & PAGE_MASK;
VM_OBJECT_WLOCK(obj);
for (i = 0; i < bp->b_npages; i++) {
m = bp->b_pages[i];
if (m == bogus_page)
panic("vfs_vmio_invalidate: Unexpected bogus page.");
bp->b_pages[i] = NULL;
presid = resid > (PAGE_SIZE - poffset) ?
(PAGE_SIZE - poffset) : resid;
KASSERT(presid >= 0, ("brelse: extra page"));
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);
vfs_vmio_unwire(bp, m);
resid -= presid;
poffset = 0;
}
VM_OBJECT_WUNLOCK(obj);
bp->b_npages = 0;
}
/*
* Page-granular truncation of an existing VMIO buffer.
*/
static void
vfs_vmio_truncate(struct buf *bp, int desiredpages)
{
vm_object_t obj;
vm_page_t m;
int i;
if (bp->b_npages == desiredpages)
return;
if (buf_mapped(bp)) {
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);
obj = bp->b_bufobj->bo_object;
if (obj != NULL)
VM_OBJECT_WLOCK(obj);
for (i = desiredpages; i < bp->b_npages; i++) {
m = bp->b_pages[i];
KASSERT(m != bogus_page, ("allocbuf: bogus page found"));
bp->b_pages[i] = NULL;
vfs_vmio_unwire(bp, m);
}
if (obj != NULL)
VM_OBJECT_WUNLOCK(obj);
bp->b_npages = desiredpages;
}
/*
* Byte granular extension of VMIO buffers.
*/
static void
vfs_vmio_extend(struct buf *bp, int desiredpages, int size)
{
/*
* We are growing the buffer, possibly in a
* byte-granular fashion.
*/
vm_object_t obj;
vm_offset_t toff;
vm_offset_t tinc;
vm_page_t m;
/*
* 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) {
/*
* 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 ), not 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;
m = bp->b_pages[pi];
vfs_buf_test_cache(bp, bp->b_offset, toff, tinc, m);
toff += tinc;
tinc = PAGE_SIZE;
}
VM_OBJECT_WUNLOCK(obj);
/*
* Step 3, fixup the KVA pmap.
*/
if (buf_mapped(bp))
bpmap_qenter(bp);
else
BUF_CHECK_UNMAPPED(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_data == unmapped_buf) ? 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);
}
/*
* getnewbuf_kva:
*
* Allocate KVA for an empty buf header according to gbflags.
*/
static int
getnewbuf_kva(struct buf *bp, int gbflags, int maxsize)
{
if ((gbflags & (GB_UNMAPPED | GB_KVAALLOC)) != GB_UNMAPPED) {
/*
* In order to keep fragmentation sane we only allocate kva
* in BKVASIZE chunks. XXX with vmem we can do page size.
*/
maxsize = (maxsize + BKVAMASK) & ~BKVAMASK;
if (maxsize != bp->b_kvasize &&
bufkva_alloc(bp, maxsize, gbflags))
return (ENOSPC);
}
return (0);
}
/*
* getnewbuf:
*
* Find and initialize a new buffer header, freeing up existing buffers
* in the bufqueues as necessary. The new buffer is returned locked.
*
* 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 )
*
* The caller is responsible for releasing the reserved bufspace after
* allocbuf() is called.
*/
static struct buf *
getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int maxsize, int gbflags)
{
struct buf *bp;
bool metadata, reserved;
bp = NULL;
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);
if (vp == NULL || (vp->v_vflag & (VV_MD | VV_SYSTEM)) != 0 ||
vp->v_type == VCHR)
metadata = true;
else
metadata = false;
atomic_add_int(&getnewbufcalls, 1);
reserved = false;
do {
if (reserved == false &&
bufspace_reserve(maxsize, metadata) != 0)
continue;
reserved = true;
if ((bp = buf_alloc()) == NULL)
continue;
if (getnewbuf_kva(bp, gbflags, maxsize) == 0)
return (bp);
break;
} while(buf_scan(false) == 0);
if (reserved)
atomic_subtract_long(&bufspace, maxsize);
if (bp != NULL) {
bp->b_flags |= B_INVAL;
brelse(bp);
}
bufspace_wait(vp, gbflags, slpflag, slptimeo);
return (NULL);
}
/*
* 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(struct vnode *vp, int target)
{
int flushed;
flushed = flushbufqueues(vp, 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.
*/
if (vp != NULL && target > 2)
target /= 2;
flushbufqueues(vp, 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(NULL, 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(struct vnode *lvp, int target, int flushdeps)
{
struct buf *sentinel;
struct vnode *vp;
struct mount *mp;
struct buf *bp;
int hasdeps;
int flushed;
int queue;
int error;
bool unlock;
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(&bqlocks[queue]);
TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist);
mtx_unlock(&bqlocks[queue]);
while (flushed != target) {
maybe_yield();
mtx_lock(&bqlocks[queue]);
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(&bqlocks[queue]);
break;
}
/*
* Skip sentinels inserted by other invocations of the
* flushbufqueues(), taking care to not reorder them.
*
* Only flush the buffers that belong to the
* vnode locked by the curthread.
*/
if (bp->b_qindex == QUEUE_SENTINEL || (lvp != NULL &&
bp->b_vp != lvp)) {
mtx_unlock(&bqlocks[queue]);
continue;
}
error = BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL);
mtx_unlock(&bqlocks[queue]);
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;
}
if (lvp == NULL) {
unlock = true;
error = vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT);
} else {
ASSERT_VOP_LOCKED(vp, "getbuf");
unlock = false;
error = VOP_ISLOCKED(vp) == LK_EXCLUSIVE ? 0 :
vn_lock(vp, LK_TRYUPGRADE);
}
if (error == 0) {
CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X",
bp, bp->b_vp, bp->b_flags);
if (curproc == bufdaemonproc) {
vfs_bio_awrite(bp);
} else {
bremfree(bp);
bwrite(bp);
notbufdflushes++;
}
vn_finished_write(mp);
if (unlock)
VOP_UNLOCK(vp, 0);
flushwithdeps += hasdeps;
flushed++;
/*
* Sleeping on runningbufspace while holding
* vnode lock leads to deadlock.
*/
if (curproc == bufdaemonproc &&
runningbufspace > hirunningspace)
waitrunningbufspace();
continue;
}
vn_finished_write(mp);
BUF_UNLOCK(bp);
}
mtx_lock(&bqlocks[queue]);
TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist);
mtx_unlock(&bqlocks[queue]);
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.
* If an unmapped buffer is provided but a mapped buffer is requested, take
* also care to properly setup mappings between pages and KVA.
*/
static void
bp_unmapped_get_kva(struct buf *bp, daddr_t blkno, int size, int gbflags)
{
int bsize, maxsize, need_mapping, need_kva;
off_t offset;
need_mapping = bp->b_data == unmapped_buf &&
(gbflags & GB_UNMAPPED) == 0;
need_kva = bp->b_kvabase == unmapped_buf &&
bp->b_data == unmapped_buf &&
(gbflags & GB_KVAALLOC) != 0;
if (!need_mapping && !need_kva)
return;
BUF_CHECK_UNMAPPED(bp);
if (need_mapping && bp->b_kvabase != unmapped_buf) {
/*
* Buffer is not mapped, but the KVA was already
* reserved at the time of the instantiation. Use the
* allocated space.
*/
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);
while (bufkva_alloc(bp, maxsize, gbflags) != 0) {
if ((gbflags & GB_NOWAIT_BD) != 0) {
/*
* XXXKIB: defragmentation cannot
* succeed, not sure what else to do.
*/
panic("GB_NOWAIT_BD and GB_UNMAPPED %p", bp);
}
atomic_add_int(&mappingrestarts, 1);
bufspace_wait(bp->b_vp, gbflags, 0, 0);
}
has_addr:
if (need_mapping) {
/* b_offset is handled by bpmap_qenter. */
bp->b_data = bp->b_kvabase;
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 successful 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 > MAXBCACHEBUF)
panic("getblk: size(%d) > MAXBCACHEBUF(%d)\n", size,
MAXBCACHEBUF);
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 inconsistent 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.
*/
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 | GB_KVAALLOC);
}
maxsize = imax(maxsize, bsize);
bp = getnewbuf(vp, slpflag, slptimeo, maxsize, flags);
if (bp == NULL) {
if (slpflag || slptimeo)
return NULL;
/*
* XXX This is here until the sleep path is diagnosed
* enough to work under very low memory conditions.
*
* There's an issue on low memory, 4BSD+non-preempt
* systems (eg MIPS routers with 32MB RAM) where buffer
* exhaustion occurs without sleeping for buffer
* reclaimation. This just sticks in a loop and
* constantly attempts to allocate a buffer, which
* hits exhaustion and tries to wakeup bufdaemon.
* This never happens because we never yield.
*
* The real solution is to identify and fix these cases
* so we aren't effectively busy-waiting in a loop
* until the reclaimation path has cycles to run.
*/
kern_yield(PRI_USER);
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);
bufspace_release(maxsize);
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);
bufspace_release(maxsize);
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, maxsize, flags)) == NULL) {
if ((flags & GB_NOWAIT_BD) &&
(curthread->td_pflags & TDP_BUFNEED) != 0)
return (NULL);
}
allocbuf(bp, size);
bufspace_release(maxsize);
bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */
BUF_ASSERT_HELD(bp);
return (bp);
}
/*
* Truncate the backing store for a non-vmio buffer.
*/
static void
vfs_nonvmio_truncate(struct buf *bp, int newbsize)
{
if (bp->b_flags & B_MALLOC) {
/*
* malloced buffers are not shrunk
*/
if (newbsize == 0) {
bufmallocadjust(bp, 0);
free(bp->b_data, M_BIOBUF);
bp->b_data = bp->b_kvabase;
bp->b_flags &= ~B_MALLOC;
}
return;
}
vm_hold_free_pages(bp, newbsize);
bufspace_adjust(bp, newbsize);
}
/*
* Extend the backing for a non-VMIO buffer.
*/
static void
vfs_nonvmio_extend(struct buf *bp, int newbsize)
{
caddr_t origbuf;
int origbufsize;
/*
* 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 (bp->b_bufsize == 0 && newbsize <= PAGE_SIZE/2 &&
bufmallocspace < maxbufmallocspace) {
bp->b_data = malloc(newbsize, M_BIOBUF, M_WAITOK);
bp->b_flags |= B_MALLOC;
bufmallocadjust(bp, newbsize);
return;
}
/*
* If the buffer is growing on its other-than-first
* allocation then we revert to the page-allocation
* scheme.
*/
origbuf = NULL;
origbufsize = 0;
if (bp->b_flags & B_MALLOC) {
origbuf = bp->b_data;
origbufsize = bp->b_bufsize;
bp->b_data = bp->b_kvabase;
bufmallocadjust(bp, 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 != NULL) {
bcopy(origbuf, bp->b_data, origbufsize);
free(origbuf, M_BIOBUF);
}
bufspace_adjust(bp, newbsize);
}
/*
* 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 inconsistent 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;
BUF_ASSERT_HELD(bp);
if (bp->b_bcount == size)
return (1);
if (bp->b_kvasize != 0 && bp->b_kvasize < size)
panic("allocbuf: buffer too small");
newbsize = roundup2(size, DEV_BSIZE);
if ((bp->b_flags & B_VMIO) == 0) {
if ((bp->b_flags & B_MALLOC) == 0)
newbsize = round_page(newbsize);
/*
* Just get anonymous memory from the kernel. Don't
* mess with B_CACHE.
*/
if (newbsize < bp->b_bufsize)
vfs_nonvmio_truncate(bp, newbsize);
else if (newbsize > bp->b_bufsize)
vfs_nonvmio_extend(bp, newbsize);
} else {
int desiredpages;
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)
vfs_vmio_truncate(bp, desiredpages);
/* XXX This looks as if it should be newbsize > b_bufsize */
else if (size > bp->b_bcount)
vfs_vmio_extend(bp, desiredpages, size);
bufspace_adjust(bp, newbsize);
}
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);
bp->bio_data = unmapped_buf;
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);
}
}
/*
* 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 occurred, 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 existence
* 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) {
/*
* Set B_CACHE if the op was a normal read and no error
* occurred. B_CACHE is set for writes in the b*write()
* routines.
*/
if (bp->b_iocmd == BIO_READ &&
!(bp->b_flags & (B_INVAL|B_NOCACHE)) &&
!(bp->b_ioflags & BIO_ERROR))
bp->b_flags |= B_CACHE;
vfs_vmio_iodone(bp);
}
/*
* 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
* consistent.
*/
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 (buf_mapped(bp)) {
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_page_sunbusy(m);
}
vm_object_pip_wakeupn(obj, bp->b_npages);
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 boundary 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
* inconsistent.
*
* Since I/O has not been initiated yet, certain buffer flags
* such as BIO_ERROR or B_INVAL may be in an inconsistent 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 && buf_mapped(bp)) {
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 (buf_mapped(bp)) {
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.
*
* This function only works with pager buffers.
*/
int
vmapbuf(struct buf *bp, int mapbuf)
{
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;
bp->b_offset = ((vm_offset_t)bp->b_data) & PAGE_MASK;
if (mapbuf || !unmapped_buf_allowed) {
pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_pages, pidx);
bp->b_data = bp->b_kvabase + bp->b_offset;
} else
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.
*
* This function only works with pager buffers.
*/
void
vunmapbuf(struct buf *bp)
{
int npages;
npages = bp->b_npages;
if (buf_mapped(bp))
pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages);
vm_page_unhold_pages(bp->b_pages, npages);
bp->b_data = unmapped_buf;
}
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 (!buf_mapped(bp)) {
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);
db_printf("b_kvabase = %p, b_kvasize = %d\n",
bp->b_kvabase, bp->b_kvasize);
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];
if (m != NULL)
db_printf("(%p, 0x%lx, 0x%lx)", m->object,
(u_long)m->pindex,
(u_long)VM_PAGE_TO_PHYS(m));
else
db_printf("( ??? )");
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_qindex == QUEUE_EMPTY)
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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