cvs commit: src/sbin/fsck_ffs fsck.h pass5.c src/sys/ufs/ffs ffs_alloc.c ffs_softdep.c fs.h

[Xin LI]

在 2005-02-20日的 18:17 -0500，David Schultz写道：
> >   Since the summary is already re-sync'ed every 30 second, we will
> >   not lag behind too much after a crash.  With this consideration
> >   in mind, it is more reasonable to transfer the responsibility to
> >   background fsck, to reduce the delay after a crash.
> 
> I'm not sure that I completely buy this explanation.  If an
> application has a 1 GB temporary file open and unlinked at the
> time of the crash, then upon reboot, this change will make it seem
> as though I have 1 GB less space than I really do.  This could
> lead to spurious disk full errors.  (Or will that happen anyway if
> bgfsck hasn't recomputed all the free block bitmaps yet?)

Hmm...   Maybe we should add some constraint on this, for example, for
volumes that fssize < 20G do the recomputation at mount time, despite
the vfs.ffs.compute_summary_at_mount setting?  I think the situation
only happens when bgfsck have not finished the scan yet, and on smaller
volumes, this should not affect so much (after all, we can always set
vfs.ffs.compute_summary_at_mount = 1 to restore the old behavior).

Should I send a HEADSUP / update UPDATING so more people will know the
change?

> I don't mean to suggest that this is a bad idea; to the contrary,
> I think it's a great idea.  But unless I'm missing something, it
> has larger adverse effects than claimed in the commit message.
> 
> FWIW, I run bgfsck on my development box once a month from a cron
> job, rather than after every crash.  As long as there's free space
> and no bugs in the filesystem or I/O system (okay, a big assumption),
> this doesn't hurt anything and saves me lots of time.

Cheers,
-- 
Xin LI <delphij delphij net>  http://www.delphij.net/
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