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Message-ID: <fe46ea3c-ef8f-40ba-f4ab-8dfe8faafb0b@nod.at>
Date: Thu, 29 Dec 2016 16:49:54 +0100
From: Richard Weinberger <richard@....at>
To: "J. Bruce Fields" <bfields@...ldses.org>
Cc: linux-mtd@...ts.infradead.org, david@...ma-star.at, tytso@....edu,
dedekind1@...il.com, adrian.hunter@...el.com,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
adilger.kernel@...ger.ca, akpm@...ux-foundation.org,
linux-ext4@...r.kernel.org
Subject: Re: [PATCH 3/6] ubifs: Use 64bit readdir cookies
Bruce,
On 29.12.2016 16:34, J. Bruce Fields wrote:
>> That way UBIFS can provide a 64bit readdir() cookie which is required for NFS3.
>
> Sounds good. And if a matching entry isn't found (as in the case of a
> concurrent unlink), what happens? The answer must be the same as for
> ext4, but I've forgotten the details.... I guess it must find the next
> highest cookie (thinking of the cookie as a 64-bit integer of some kind)
> that exists in the directory. And that must be the same order that
> readdir normally returns entries in.
If a 64bit cookie is not found, the lookup function returns -ENOENT.
In UBIFS we cannot just select a higher or lower key (cookie in this case),
since it is the B-tree key and would point to a completely different
entry.
So, in case of a concurrent unlink() one would succeed and one fail with
-ENOENT. Unless I miss something that seems okay to me.
Thanks,
//richard
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