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Date:   Fri, 12 Jul 2019 16:00:27 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Aleksa Sarai <cyphar@cyphar.com>
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        "J. Bruce Fields" <bfields@fieldses.org>,
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Subject: Re: [PATCH v9 05/10] namei: O_BENEATH-style path resolution flags
Message-ID: <20190712150026.GO17978@ZenIV.linux.org.uk>
References: <20190706145737.5299-1-cyphar@cyphar.com>
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On Fri, Jul 12, 2019 at 02:25:53PM +0100, Al Viro wrote:

> 	if (flags & LOOKUP_BENEATH) {
> 		nd->root = nd->path;
> 		if (!(flags & LOOKUP_RCU))
> 			path_get(&nd->root);
> 		else
> 			nd->root_seq = nd->seq;

BTW, this assignment is needed for LOOKUP_RCU case.  Without it
you are pretty much guaranteed that lazy pathwalk will fail,
when it comes to complete_walk().

Speaking of which, what would happen if LOOKUP_ROOT/LOOKUP_BENEATH
combination would someday get passed?