Date: Mon, 26 Sep 2005 05:11:09 +0300 From: Giorgos Keramidas <keramida@linux.gr> To: Frank Mayhar <frank@exit.com> Cc: FreeBSD-hackers@freebsd.org Subject: Re: Oddity in libufs. Message-ID: <20050926021109.GA2576@flame.pc> In-Reply-To: <20050925110005.GB819@flame.pc> References: <1127618793.38683.9.camel@realtime.exit.com> <20050925110005.GB819@flame.pc>
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On 2005-09-25 14:00, Giorgos Keramidas <keramida@linux.gr> wrote:
> On 2005-09-24 20:26, Frank Mayhar <frank@exit.com> wrote:
> > I've been using libufs as the I/O mechanism for my (heavy) modification
> > of sysutils/ffsrecov. It's working to my needs and now I'm poking at
> > other bits and pieces to maybe get it suitable for release into the
> > wild. I just looked at cgread() to see what it does and noticed that
> > there seems to be a redundant line:
> >
> > .
> > .
> > if (c >= fs->fs_ncg) {
> > return (0);
> > }
> > ccg = fsbtodb(fs, cgtod(fs, c)) * disk->d_bsize;
> > if (bread(disk, fsbtodb(fs, cgtod(fs, c)), disk->d_cgunion.d_buf,
> > .
> > .
> >
> > That assignment up there looks redundant, as ccg is never used. I
> > suspect that it's a relic of an old lseek()/read() pair that's long
> > gone.
>
> It's probably easy to verify that without this assignment 'ccg' is an
> unused var:
>
> - Comment it out
> - Rebuild with an elevated WARNS level
>
> if a warning about 'unused ccg var' is printed, then you are certain
> that ccg was only used for the assignment.
FWIW,
libufs built with the following patch seems to pass at least a build
test fine, even with WARNS=6
%%%
Index: cgroup.c
===================================================================
RCS file: /home/ncvs/src/lib/libufs/cgroup.c,v
retrieving revision 1.3
diff -u -r1.3 cgroup.c
--- cgroup.c 9 Jun 2003 09:32:29 -0000 1.3
+++ cgroup.c 26 Sep 2005 02:09:07 -0000
@@ -55,14 +55,12 @@
cgread1(struct uufsd *disk, int c)
{
struct fs *fs;
- off_t ccg;
fs = &disk->d_fs;
if (c >= fs->fs_ncg) {
return (0);
}
- ccg = fsbtodb(fs, cgtod(fs, c)) * disk->d_bsize;
if (bread(disk, fsbtodb(fs, cgtod(fs, c)), disk->d_cgunion.d_buf,
fs->fs_bsize) == -1) {
ERROR(disk, "unable to read cylinder group");
%%%
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