Date: Fri, 27 Feb 1998 17:07:05 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Eivind Eklund <eivind@yes.no> Cc: fs@FreeBSD.ORG Subject: Re: syncer / SMP question Message-ID: <3416.888595625@critter.freebsd.dk> In-Reply-To: Your message of "Fri, 27 Feb 1998 16:48:59 %2B0100." <19980227164859.25557@follo.net>
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Uhm, this is part&parcel of Kirks softupdate code,
so I wouldn't bother if I were you...
Poul-Henning
In message <19980227164859.25557@follo.net>, Eivind Eklund writes:
>I was looking at implementing an incremental syncer for UFS, as a sort
>of "let's get to know the FS-code" project, and noticed something that
>looked like really strange code in the sync() syscall. Is there any
>reason why the below wouldn't be a benign change? The extra
>simplelock-call looks especially weird - it looks like either the lock
>is released somewhere else, or we'll have the mountlist locked many
>times.
>
>If it looks like a benign change, what would I do to test it properly?
>I can allocate a scratch machine to do this if there is no need for
>really long-running tests. I can probably even do a scratchable
>SMP-box.
>
>cvs diff: Diffing .
>Index: vfs_syscalls.c
>===================================================================
>RCS file: /home/ncvs/src/sys/kern/vfs_syscalls.c,v
>retrieving revision 1.93
>diff -u -u -5 -r1.93 vfs_syscalls.c
>--- vfs_syscalls.c 1998/02/15 04:17:09 1.93
>+++ vfs_syscalls.c 1998/02/27 15:37:16
>@@ -480,24 +480,21 @@
> register struct mount *mp, *nmp;
> int asyncflag;
>
> simple_lock(&mountlist_slock);
> for (mp = mountlist.cqh_first; mp != (void *)&mountlist; mp = nmp) {
>+ nmp = mp->mnt_list.cqe_next;
> if (vfs_busy(mp, LK_NOWAIT, &mountlist_slock, p)) {
>- nmp = mp->mnt_list.cqe_next;
> continue;
> }
> if ((mp->mnt_flag & MNT_RDONLY) == 0) {
> asyncflag = mp->mnt_flag & MNT_ASYNC;
> mp->mnt_flag &= ~MNT_ASYNC;
> vfs_msync(mp, MNT_NOWAIT);
> VFS_SYNC(mp, MNT_NOWAIT, p != NULL ? p->p_ucred : NOC
>RED, p);
>- if (asyncflag)
>- mp->mnt_flag |= MNT_ASYNC;
>+ mp->mnt_flag |= asyncflag;
> }
>- simple_lock(&mountlist_slock);
>- nmp = mp->mnt_list.cqe_next;
> vfs_unbusy(mp, p);
> }
> simple_unlock(&mountlist_slock);
> #if 0
> /*
>
>Eivind.
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>
--
Poul-Henning Kamp FreeBSD coreteam member
phk@FreeBSD.ORG "Real hackers run -current on their laptop."
"Drink MONO-tonic, it goes down but it will NEVER come back up!"
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