Date: Thu, 10 Jun 2004 20:13:29 -0500 From: Brian Bergstrand <brian@classicalguitar.net> To: fs@freebsd.org Subject: Ext2 vs UFS getlbns Message-ID: <8C40210D-BB44-11D8-B357-0003930A674E@classicalguitar.net>
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I just noticed something in ext2_getlbns() (ext2_bmap.c, v1.57) vs.
ufs_getlbns() (ufs_bmap.c, v1.60)
In the last loop to setup the indir array,
UFS does:
{
...
blockcnt /= MNINDIR(ump);
off = (bn / blockcnt) % MNINDIR(ump);
++numlevels;
ap->in_lbn = metalbn;
ap->in_off = off;
ap->in_exists = 0;
++ap;
metalbn -= -1 + off * blockcnt;
}
While Ext2 does:
{
...
off = (bn / blockcnt) % MNINDIR(ump);
++numlevels;
ap->in_lbn = metalbn;
ap->in_off = off;
ap->in_exists = 0;
++ap;
metalbn -= -1 + off * blockcnt;
blockcnt /= MNINDIR(ump);
}
Notice that blockcnt is calculated AFTER the offset in Ext2 and BEFORE
the offset in UFS.
Was this change in Ext2 done on purpose for some reason, or does it not
make a difference? I would think with some block block #'s it would.
Thanks.
Brian Bergstrand <http://www.bergstrand.org/brian/>, AIM: triryche206
PGP Key: <http://www.bergstrand.org/brian/misc/public_key.txt>;
Hell, there are no rules here--we're trying to accomplish something. -
Thomas A. Edison
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"Lawn Boy" by "Phish"
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