Re: [PATCH] Useless inode semaphore locking in 2.4.0-test8

From: Linus Torvalds (torvalds@transmeta.com)
Date: Tue Sep 19 2000 - 14:02:36 EST


In article <200009151200.OAA00850@mailhost.ri.silicomp.fr>,
Eric PAIRE <eric.paire@ri.silicomp.fr> wrote:
>
>In open.c:do_truncate(), the call to notify_change() is protected by
>the inode->i_sem, which seems to me useless, and thus can be removed.

And exactly how do you now protect against the race of another process
doing a write() at the same time, and in particular the updates of
"inode->i_size"?

As far as I can tell, you removing the semaphore means that _nothing_
protects inode->i_size any more, and you can get basically random
values. That would be bad.

                Linus
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