NetBSD/sys/miscfs/syncfs/sync_subr.c

257 lines
7.1 KiB
C

/* $NetBSD: sync_subr.c,v 1.8 2000/11/27 08:39:46 chs Exp $ */
/*
* Copyright 1997 Marshall Kirk McKusick. All Rights Reserved.
*
* This code is derived from work done by Greg Ganger at the
* University of Michigan.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. None of the names of McKusick, Ganger, or the University of Michigan
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY MARSHALL KIRK MCKUSICK ``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 MARSHALL KIRK MCKUSICK 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.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/buf.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <miscfs/genfs/genfs.h>
#include <miscfs/syncfs/syncfs.h>
/*
* Defines and variables for the syncer process.
*/
int syncer_maxdelay = SYNCER_MAXDELAY; /* maximum delay time */
time_t syncdelay = 30; /* max time to delay syncing data */
time_t filedelay = 30; /* time to delay syncing files */
time_t dirdelay = 15; /* time to delay syncing directories */
time_t metadelay = 10; /* time to delay syncing metadata */
struct lock syncer_lock; /* used to freeze syncer */
static int rushjob; /* number of slots to run ASAP */
static int stat_rush_requests; /* number of times I/O speeded up */
static int syncer_delayno = 0;
static long syncer_last;
static struct synclist *syncer_workitem_pending;
struct proc *updateproc = NULL;
void
vn_initialize_syncerd()
{
int i;
syncer_last = SYNCER_MAXDELAY + 2;
syncer_workitem_pending = malloc(syncer_last * sizeof (struct synclist),
M_VNODE, M_WAITOK);
for (i = 0; i < syncer_last; i++)
LIST_INIT(&syncer_workitem_pending[i]);
lockinit(&syncer_lock, PVFS, "synclk", 0, 0);
}
/*
* The workitem queue.
*
* It is useful to delay writes of file data and filesystem metadata
* for tens of seconds so that quickly created and deleted files need
* not waste disk bandwidth being created and removed. To realize this,
* we append vnodes to a "workitem" queue. When running with a soft
* updates implementation, most pending metadata dependencies should
* not wait for more than a few seconds. Thus, mounted on block devices
* are delayed only about a half the time that file data is delayed.
* Similarly, directory updates are more critical, so are only delayed
* about a third the time that file data is delayed. Thus, there are
* SYNCER_MAXDELAY queues that are processed round-robin at a rate of
* one each second (driven off the filesystem syner process). The
* syncer_delayno variable indicates the next queue that is to be processed.
* Items that need to be processed soon are placed in this queue:
*
* syncer_workitem_pending[syncer_delayno]
*
* A delay of fifteen seconds is done by placing the request fifteen
* entries later in the queue:
*
* syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask]
*
*/
/*
* Add an item to the syncer work queue.
*/
void
vn_syncer_add_to_worklist(vp, delay)
struct vnode *vp;
int delay;
{
int s, slot;
s = splbio();
if (vp->v_flag & VONWORKLST) {
LIST_REMOVE(vp, v_synclist);
}
if (delay > syncer_maxdelay - 2)
delay = syncer_maxdelay - 2;
slot = (syncer_delayno + delay) % syncer_last;
LIST_INSERT_HEAD(&syncer_workitem_pending[slot], vp, v_synclist);
vp->v_flag |= VONWORKLST;
splx(s);
}
/*
* Remove an item fromthe syncer work queue.
*/
void
vn_syncer_remove_from_worklist(vp)
struct vnode *vp;
{
int s;
s = splbio();
if (vp->v_flag & VONWORKLST) {
LIST_REMOVE(vp, v_synclist);
}
splx(s);
}
/*
* System filesystem synchronizer daemon.
*/
void
sched_sync(v)
void *v;
{
struct synclist *slp;
struct vnode *vp;
long starttime;
int s;
updateproc = curproc;
for (;;) {
starttime = time.tv_sec;
/*
* Push files whose dirty time has expired. Be careful
* of interrupt race on slp queue.
*/
s = splbio();
slp = &syncer_workitem_pending[syncer_delayno];
syncer_delayno += 1;
if (syncer_delayno >= syncer_last)
syncer_delayno = 0;
splx(s);
lockmgr(&syncer_lock, LK_EXCLUSIVE, NULL);
while ((vp = LIST_FIRST(slp)) != NULL) {
if (VOP_ISLOCKED(vp) == 0) {
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
(void) VOP_FSYNC(vp, curproc->p_ucred,
FSYNC_LAZY, 0, 0, curproc);
VOP_UNLOCK(vp, 0);
}
s = splbio();
if (LIST_FIRST(slp) == vp) {
/*
* Put us back on the worklist. The worklist
* routine will remove us from our current
* position and then add us back in at a later
* position.
*/
vn_syncer_add_to_worklist(vp, syncdelay);
}
splx(s);
}
/*
* Do soft update processing.
*/
if (bioops.io_sync)
(*bioops.io_sync)(NULL);
lockmgr(&syncer_lock, LK_RELEASE, NULL);
/*
* The variable rushjob allows the kernel to speed up the
* processing of the filesystem syncer process. A rushjob
* value of N tells the filesystem syncer to process the next
* N seconds worth of work on its queue ASAP. Currently rushjob
* is used by the soft update code to speed up the filesystem
* syncer process when the incore state is getting so far
* ahead of the disk that the kernel memory pool is being
* threatened with exhaustion.
*/
if (rushjob > 0) {
rushjob--;
continue;
}
/*
* If it has taken us less than a second to process the
* current work, then wait. Otherwise start right over
* again. We can still lose time if any single round
* takes more than two seconds, but it does not really
* matter as we are just trying to generally pace the
* filesystem activity.
*/
if (time.tv_sec == starttime)
tsleep(&rushjob, PPAUSE, "syncer", hz);
}
}
/*
* Request the syncer daemon to speed up its work.
* We never push it to speed up more than half of its
* normal turn time, otherwise it could take over the cpu.
*/
int
speedup_syncer()
{
if (rushjob >= syncdelay / 2) {
return (0);
}
rushjob++;
wakeup(&rushjob);
stat_rush_requests += 1;
return (1);
}