2007-04-11 20:20:00

by Eric Sandeen

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Subject: debugfs fill_bgs command?

I was wondering if others think it would be useful to have a "fill_bgs"
command in debugfs; this would (minimally) mark the lower X bgs as full
for both inodes & blocks (possibly either/or), to allow testing the
higher block groups. I'm using a hacked up version of this to do a
little ext3 testing above 8T. Given that this would really only be a
testing option in nature, would it be accepted into e2fsprogs? I'd
probably need some sort of "unfill" command as well, to put the bg
counters back where they should be; probably by actually reading the
bitmaps. This way fsck would still find a consistent filesystem...

I had originally written a set_bg_field function too, to go with inode &
sb variants, though for marking the first few thousand bg's it was going
to get a bit tedious... :)

Thoughts?

Thanks,
-Eric


2007-04-11 22:52:39

by Andreas Dilger

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Subject: Re: debugfs fill_bgs command?

On Apr 11, 2007 15:17 -0500, Eric Sandeen wrote:
> I was wondering if others think it would be useful to have a "fill_bgs"
> command in debugfs; this would (minimally) mark the lower X bgs as full
> for both inodes & blocks (possibly either/or), to allow testing the
> higher block groups. I'm using a hacked up version of this to do a
> little ext3 testing above 8T. Given that this would really only be a
> testing option in nature, would it be accepted into e2fsprogs? I'd
> probably need some sort of "unfill" command as well, to put the bg
> counters back where they should be; probably by actually reading the
> bitmaps. This way fsck would still find a consistent filesystem...
>
> I had originally written a set_bg_field function too, to go with inode &
> sb variants, though for marking the first few thousand bg's it was going
> to get a bit tedious... :)

Try "mke2fs -O lazy_bg XXX" and be happy. Can be used on any kernel as
it is a COMPAT feature and marks all but first and last groups as full.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

2007-04-12 01:22:28

by Eric Sandeen

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Subject: Re: debugfs fill_bgs command?

Andreas Dilger wrote:

> Try "mke2fs -O lazy_bg XXX" and be happy. Can be used on any kernel as
> it is a COMPAT feature and marks all but first and last groups as full.

Ugh, how'd I miss that. :)

Thanks...

-Eric