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/* $OpenBSD: vfs_sync.c,v 1.39 2006/04/30 14:20:07 sturm Exp $ */
/*
* Portions of this code are:
*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Syncer daemon
*/
#include <sys/queue.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/buf.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/sched.h>
#ifdef FFS_SOFTUPDATES
int softdep_process_worklist(struct mount *);
#endif
/*
* The workitem queue.
*/
#define SYNCER_MAXDELAY 32 /* maximum sync delay time */
#define SYNCER_DEFAULT 30 /* default sync delay time */
int syncer_maxdelay = SYNCER_MAXDELAY; /* maximum delay time */
time_t syncdelay = SYNCER_DEFAULT; /* time to delay syncing vnodes */
int rushjob = 0; /* number of slots to run ASAP */
int stat_rush_requests = 0; /* number of rush requests */
static int syncer_delayno = 0;
static long syncer_mask;
LIST_HEAD(synclist, vnode);
static struct synclist *syncer_workitem_pending;
struct proc *syncerproc;
/*
* 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 syncer 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]
*
*/
void
vn_initialize_syncerd(void)
{
syncer_workitem_pending = hashinit(syncer_maxdelay, M_VNODE, M_WAITOK,
&syncer_mask);
syncer_maxdelay = syncer_mask + 1;
}
/*
* Add an item to the syncer work queue.
*/
void
vn_syncer_add_to_worklist(struct vnode *vp, int delay)
{
int s, slot;
if (delay > syncer_maxdelay - 2)
delay = syncer_maxdelay - 2;
slot = (syncer_delayno + delay) & syncer_mask;
s = splbio();
if (vp->v_bioflag & VBIOONSYNCLIST)
LIST_REMOVE(vp, v_synclist);
vp->v_bioflag |= VBIOONSYNCLIST;
LIST_INSERT_HEAD(&syncer_workitem_pending[slot], vp, v_synclist);
splx(s);
}
/*
* System filesystem synchronizer daemon.
*/
void
sched_sync(struct proc *p)
{
struct synclist *slp;
struct vnode *vp;
long starttime;
int s;
syncerproc = curproc;
for (;;) {
starttime = time_second;
/*
* Push files whose dirty time has expired.
*/
s = splbio();
slp = &syncer_workitem_pending[syncer_delayno];
syncer_delayno += 1;
if (syncer_delayno == syncer_maxdelay)
syncer_delayno = 0;
while ((vp = LIST_FIRST(slp)) != NULL) {
if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT, p)) {
/*
* If we fail to get the lock, we move this
* vnode one second ahead in time.
* XXX - no good, but the best we can do.
*/
vn_syncer_add_to_worklist(vp, 1);
continue;
}
splx(s);
(void) VOP_FSYNC(vp, p->p_ucred, MNT_LAZY, p);
vput(vp);
s = splbio();
if (LIST_FIRST(slp) == vp) {
/*
* Note: disk vps can remain on the
* worklist too with no dirty blocks, but
* since sync_fsync() moves it to a different
* slot we are safe.
*/
#ifdef DIAGNOSTIC
if (LIST_FIRST(&vp->v_dirtyblkhd) == NULL &&
vp->v_type != VBLK) {
vprint("fsync failed", vp);
if (vp->v_mount != NULL)
printf("mounted on: %s\n",
vp->v_mount->mnt_stat.f_mntonname);
panic("sched_sync: fsync failed");
}
#endif /* DIAGNOSTIC */
/*
* 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);
#ifdef FFS_SOFTUPDATES
/*
* Do soft update processing.
*/
softdep_process_worklist(NULL);
#endif
/*
* 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 -= 1;
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_second == starttime)
tsleep(&lbolt, PPAUSE, "syncer", 0);
}
}
/*
* 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(void)
{
int s;
SCHED_LOCK(s);
if (syncerproc && syncerproc->p_wchan == &lbolt)
setrunnable(syncerproc);
SCHED_UNLOCK(s);
if (rushjob < syncdelay / 2) {
rushjob += 1;
stat_rush_requests += 1;
return 1;
}
return 0;
}
/*
* Routine to create and manage a filesystem syncer vnode.
*/
#define sync_close nullop
int sync_fsync(void *);
int sync_inactive(void *);
#define sync_reclaim nullop
#define sync_lock vop_generic_lock
#define sync_unlock vop_generic_unlock
int sync_print(void *);
#define sync_islocked vop_generic_islocked
int (**sync_vnodeop_p)(void *);
struct vnodeopv_entry_desc sync_vnodeop_entries[] = {
{ &vop_default_desc, vn_default_error },
{ &vop_close_desc, sync_close }, /* close */
{ &vop_fsync_desc, sync_fsync }, /* fsync */
{ &vop_inactive_desc, sync_inactive }, /* inactive */
{ &vop_reclaim_desc, sync_reclaim }, /* reclaim */
{ &vop_lock_desc, sync_lock }, /* lock */
{ &vop_unlock_desc, sync_unlock }, /* unlock */
{ &vop_print_desc, sync_print }, /* print */
{ &vop_islocked_desc, sync_islocked }, /* islocked */
{ (struct vnodeop_desc*)NULL, (int(*)(void *))NULL }
};
struct vnodeopv_desc sync_vnodeop_opv_desc = {
&sync_vnodeop_p, sync_vnodeop_entries
};
/*
* Create a new filesystem syncer vnode for the specified mount point.
*/
int
vfs_allocate_syncvnode(struct mount *mp)
{
struct vnode *vp;
static long start, incr, next;
int error;
/* Allocate a new vnode */
if ((error = getnewvnode(VT_VFS, mp, sync_vnodeop_p, &vp)) != 0) {
mp->mnt_syncer = NULL;
return (error);
}
vp->v_writecount = 1;
vp->v_type = VNON;
/*
* Place the vnode onto the syncer worklist. We attempt to
* scatter them about on the list so that they will go off
* at evenly distributed times even if all the filesystems
* are mounted at once.
*/
next += incr;
if (next == 0 || next > syncer_maxdelay) {
start /= 2;
incr /= 2;
if (start == 0) {
start = syncer_maxdelay / 2;
incr = syncer_maxdelay;
}
next = start;
}
vn_syncer_add_to_worklist(vp, next);
mp->mnt_syncer = vp;
return (0);
}
/*
* Do a lazy sync of the filesystem.
*/
int
sync_fsync(void *v)
{
struct vop_fsync_args /* {
struct vnodeop_desc *a_desc;
struct vnode *a_vp;
struct ucred *a_cred;
int a_waitfor;
struct proc *a_p;
} */ *ap = v;
struct vnode *syncvp = ap->a_vp;
struct mount *mp = syncvp->v_mount;
int asyncflag;
/*
* We only need to do something if this is a lazy evaluation.
*/
if (ap->a_waitfor != MNT_LAZY)
return (0);
/*
* Move ourselves to the back of the sync list.
*/
vn_syncer_add_to_worklist(syncvp, syncdelay);
/*
* Walk the list of vnodes pushing all that are dirty and
* not already on the sync list.
*/
if (vfs_busy(mp, LK_NOWAIT) == 0) {
asyncflag = mp->mnt_flag & MNT_ASYNC;
mp->mnt_flag &= ~MNT_ASYNC;
VFS_SYNC(mp, MNT_LAZY, ap->a_cred, ap->a_p);
if (asyncflag)
mp->mnt_flag |= MNT_ASYNC;
vfs_unbusy(mp);
}
return (0);
}
/*
* The syncer vnode is no longer needed and is being decommissioned.
*/
int
sync_inactive(void *v)
{
struct vop_inactive_args /* {
struct vnodeop_desc *a_desc;
struct vnode *a_vp;
struct proc *a_p;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
int s;
if (vp->v_usecount == 0) {
VOP_UNLOCK(vp, 0, ap->a_p);
return (0);
}
vp->v_mount->mnt_syncer = NULL;
s = splbio();
LIST_REMOVE(vp, v_synclist);
vp->v_bioflag &= ~VBIOONSYNCLIST;
splx(s);
vp->v_writecount = 0;
vput(vp);
return (0);
}
/*
* Print out a syncer vnode.
*/
int
sync_print(void *v)
{
printf("syncer vnode\n");
return (0);
}
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