Re: [PATCH v5] fs: clear file privilege bits when mmap writing

From: Al Viro
Date: Thu Dec 10 2015 - 14:34:22 EST

On Thu, Dec 10, 2015 at 07:16:11PM +0100, Willy Tarreau wrote:

> > Is f_flags safe to write like this without holding a lock?
> Unfortunately I have no idea. I've seen places where it's written without
> taking a lock such as in blkdev_open() and I don't think that this one is
> called with a lock held.

In any ->open() we obviously have nobody else able to find that struct file,
let alone modify it, so there the damn thing is essentially caller-private
and no locking is needed.
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