Reducing UFS corruption from unclean shutdowns?

[Warner Losh]

On Fri, Jun 21, 2019, 3:33 PM Conrad Meyer <cem at freebsd.org> wrote:

> On Fri, Jun 21, 2019 at 2:55 PM Alan Somers <asomers at freebsd.org> wrote:
> > I would've thought that immediately following a sync(8), the
> > filesystem would be consistent.  Why do I still see errors after a
> > panic in files that were written before I sync()ed?
> > -Alan
>
> Hi Alan,
>
> Contra the name, sync(2) (sync(8)) isn't synchronous.  It invokes
> VFS_SYNC() with MNT_NOWAIT across all mountpoints.
>

Yes. Sync(2) just starts the I/O, but it may be delayed if there is a lot
of dirty buffers. The other issue is that new buffers may be dirtied...

Warner

Cheers,
> Conrad
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