linux-kernel - Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE

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Message-ID: <20201013213222.wlnhiocw6zi5eegx@wittgenstein>
Date:   Tue, 13 Oct 2020 23:32:22 +0200
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     Giuseppe Scrivano <gscrivan@...hat.com>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        containers@...ts.linux-foundation.org
Subject: Re: [PATCH 1/2] fs, close_range: add flag CLOSE_RANGE_CLOEXEC

On Tue, Oct 13, 2020 at 10:09:25PM +0100, Al Viro wrote:
> On Tue, Oct 13, 2020 at 04:06:08PM +0200, Giuseppe Scrivano wrote:
> > +		spin_lock(&cur_fds->file_lock);
> > +		fdt = files_fdtable(cur_fds);
> > +		cur_max = fdt->max_fds - 1;
> > +		max_fd = min(max_fd, cur_max);
> > +		while (fd <= max_fd)
> > +			__set_close_on_exec(fd++, fdt);
> > +		spin_unlock(&cur_fds->file_lock);
> 
> 	First of all, this is an atrocious way to set all bits
> in a range.  What's more, you don't want to set it for *all*

Hm, good point.

Would it make sense to just use the bitmap_set() proposal since the 3 to
~0 case is most common or to actually iterate based on the open fds?


Christian