From: Al Viro <viro@zeniv.linux.org.uk>
To: Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
"J . Bruce Fields" <bfields@redhat.com>
Subject: Re: [PATCH] exportfs: fix handling of rename race in reconnect_one()
Date: Thu, 6 Feb 2020 21:45:18 +0000 [thread overview]
Message-ID: <20200206214518.GB23230@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20200126220800.32397-1-amir73il@gmail.com>
On Mon, Jan 27, 2020 at 12:08:00AM +0200, Amir Goldstein wrote:
> If a disconnected dentry gets looked up and renamed between the
> call to exportfs_get_name() and lookup_one_len_unlocked(), and if also
> lookup_one_len_unlocked() returns ERR_PTR(-ENOENT), maybe because old
> parent was deleted, we return an error, although dentry may be connected.
>
> Commit 909e22e05353 ("exportfs: fix 'passing zero to ERR_PTR()'
> warning") changes this behavior from always returning success,
> regardless if dentry was reconnected by somoe other task, to always
> returning a failure.
>
> Change the lookup error handling to match that of exportfs_get_name()
> error handling and return success after getting -ENOENT and verifying
> that some other task has connected the dentry for us.
It's not that simple, unfortunately. For one thing, lookup_one_len_unlocked()
will normally return a negative dentry, not ERR_PTR(-ENOENT). For another,
it *can* fail for any number of other reasons (-ENOMEM, for example), without
anyone having ever looked it up.
So I agree that the damn thing needs work, but I don't believe that this
is the right fix.
next prev parent reply other threads:[~2020-02-06 21:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-26 22:08 [PATCH] exportfs: fix handling of rename race in reconnect_one() Amir Goldstein
2020-01-27 8:04 ` Christoph Hellwig
2020-01-27 17:30 ` J. Bruce Fields
2020-01-27 18:38 ` Amir Goldstein
2020-01-27 21:17 ` J. Bruce Fields
2020-02-06 20:22 ` Amir Goldstein
2020-02-06 21:10 ` J. Bruce Fields
2020-02-06 21:45 ` Al Viro [this message]
2020-02-07 6:26 ` Amir Goldstein
2020-03-13 14:33 ` Amir Goldstein
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