John Rudd wrote:
Hm. Your patch seems to do this:
change:
lock/unlock from current to eof
to:
seek 0
lock/unlock from (current=0) to eof
Which means you're potentially destroying the notion of "current" (I
don't know if that's important in AFS code or not, but it seems like, at
best, a bad idea ... and at worst, a potentially disastrous idea).
If you look at the code you'll see that in all cases an explicit seek
is done before any read/write. Funny enough, usually after the lockf()
meaning the lock wasn't on the right "section" anyway.
I would suggest:
save current to tmp
seek 0
lock/unlock from (current=0) to eof
seek tmp
Right, only that for a correct flock() emulation you'd also have to
hold the necessary locks to prevent another thread from seeking away
between the two calls... ideally something that is independent of the
namei locking. And the code would gain in readability had the ifdefs
been packed into a macro or subroutine.
In this precise context however, and without wiping cleaner than
clean: why spend yet another system call on something that nobody
cares about.
--
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Rainer Toebbicke
European Laboratory for Particle Physics(CERN) - Geneva, Switzerland
Phone: +41 22 767 8985 Fax: +41 22 767 7155
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