Date: Sun, 02 Apr 2006 20:48:51 +0000 (UTC) From: Tor Egge <Tor.Egge@cvsup.no.freebsd.org> To: peter@holm.cc Cc: truckman@freebsd.org, current@freebsd.org Subject: Re: Livelock / softdep_flush "loop" Message-ID: <20060402.204851.78799557.Tor.Egge@cvsup.no.freebsd.org> In-Reply-To: <20060402190910.GA12759@peter.osted.lan> References: <20060402094431.GA81954@peter.osted.lan> <20060402.180153.74658240.Tor.Egge@cvsup.no.freebsd.org> <20060402190910.GA12759@peter.osted.lan>
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> > The enclosed patch might help.
> >
>
> I'm testing it right now.
Similarly to the softdepflush process looping in softdep_flush(), the process
creating a snapshot might loop in ffs_sync().
- Tor Egge
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Index: sys/ufs/ffs/ffs_softdep.c
===================================================================
RCS file: /home/ncvs/src/sys/ufs/ffs/ffs_softdep.c,v
retrieving revision 1.193
diff -u -r1.193 ffs_softdep.c
--- sys/ufs/ffs/ffs_softdep.c 12 Mar 2006 05:25:16 -0000 1.193
+++ sys/ufs/ffs/ffs_softdep.c 2 Apr 2006 20:20:15 -0000
@@ -718,6 +718,7 @@
{
struct mount *nmp;
struct mount *mp;
+ struct ufsmount *ump;
struct thread *td;
int remaining;
int vfslocked;
@@ -752,7 +753,9 @@
continue;
vfslocked = VFS_LOCK_GIANT(mp);
softdep_process_worklist(mp, 0);
- remaining += VFSTOUFS(mp)->softdep_on_worklist;
+ ump = VFSTOUFS(mp);
+ remaining += ump->softdep_on_worklist -
+ ump->softdep_on_worklist_inprogress;
VFS_UNLOCK_GIANT(vfslocked);
mtx_lock(&mountlist_mtx);
nmp = TAILQ_NEXT(mp, mnt_list);
@@ -914,11 +917,17 @@
if ((flags & LK_NOWAIT) == 0 || wk->wk_type != D_DIRREM)
break;
wk->wk_state |= INPROGRESS;
+ ump->softdep_on_worklist_inprogress++;
FREE_LOCK(&lk);
ffs_vget(mp, WK_DIRREM(wk)->dm_oldinum,
LK_NOWAIT | LK_EXCLUSIVE, &vp);
ACQUIRE_LOCK(&lk);
wk->wk_state &= ~INPROGRESS;
+ if (--ump->softdep_on_worklist_inprogress == 0 &&
+ ump->softdep_on_worklist_inprogress_req != 0) {
+ ump->softdep_on_worklist_inprogress_req = 0;
+ wakeup(&ump->softdep_on_worklist_inprogress);
+ }
if (vp != NULL)
break;
}
@@ -6099,6 +6108,17 @@
VI_LOCK(devvp);
continue;
}
+ if (ump->softdep_on_worklist_inprogress != 0) {
+ VI_UNLOCK(devvp);
+ ump->softdep_on_worklist_inprogress_req = 1;
+ msleep(&ump->softdep_on_worklist_inprogress,
+ &lk,
+ (PUSER - 1) | PDROP,
+ "sdipdr" /* soft dep in progress drain */,
+ 0);
+ VI_LOCK(devvp);
+ continue;
+ }
if (!MNT_ITRYLOCK(mp)) {
FREE_LOCK(&lk);
VI_UNLOCK(devvp);
Index: sys/ufs/ufs/ufsmount.h
===================================================================
RCS file: /home/ncvs/src/sys/ufs/ufs/ufsmount.h,v
retrieving revision 1.36
diff -u -r1.36 ufsmount.h
--- sys/ufs/ufs/ufsmount.h 8 Mar 2006 23:43:39 -0000 1.36
+++ sys/ufs/ufs/ufsmount.h 2 Apr 2006 20:20:15 -0000
@@ -76,6 +76,8 @@
struct workhead softdep_workitem_pending; /* softdep work queue */
struct worklist *softdep_worklist_tail; /* Tail pointer for above */
int softdep_on_worklist; /* Items on the worklist */
+ int softdep_on_worklist_inprogress; /* Busy items on worklist */
+ int softdep_on_worklist_inprogress_req;/* Wakeup when not busy */
int softdep_deps; /* Total dependency count */
int softdep_accdeps; /* accumulated dep count */
int softdep_req; /* Wakeup when deps hits 0. */
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