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From: Amir Goldstein <amir73il@gmail.com>
To: Stan Hu <stanhu@gmail.com>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	overlayfs <linux-unionfs@vger.kernel.org>,
	Miklos Szeredi <miklos@szeredi.hu>
Subject: Re: overlay2: backporting a copy_file_range bug fix in Linux 5.6 to 5.10?
Date: Sat, 4 Dec 2021 09:15:16 +0200	[thread overview]
Message-ID: <CAOQ4uxipkWdJaBTYem_VVyZpxkgf5yfrY5xru8Agfe+BS7S0eQ@mail.gmail.com> (raw)
In-Reply-To: <CAMBWrQnfGuMjF6pQfoj9U5abKBQpaYtSH11QFo4+jZrL32XUEg@mail.gmail.com>

On Fri, Dec 3, 2021 at 8:20 PM Stan Hu <stanhu@gmail.com> wrote:
>
> A number of users have reported that under certain conditions using
> Docker and overlay2, copy_file_range() can unexpectedly create a
> 0-byte file: In https://github.com/docker/for-linux/issues/1015.
>
> We started seeing mysterious failures in our CI tests as a result of
> files not properly being copied.
>
> https://github.com/docker/for-linux/issues/1015#issuecomment-841915668
> has a sample reproduction test.
>
> I analyzed the diff between 5.10 and 5.11 and found that if I applied
> the following kernel patch, the reproduction test passes:
>
> https://lore.kernel.org/linux-fsdevel/20201207163255.564116-6-mszeredi@redhat.com/#t
>
> This landed in this merge commit and this commit:
>
> 1. https://github.com/torvalds/linux/commit/92dbc9dedccb9759c7f9f2f0ae6242396376988f
> 2. https://github.com/torvalds/linux/commit/82a763e61e2b601309d696d4fa514c77d64ee1be
>
> Could this patch be backported for kernels 5.6 to 5.10?

This problem is a regression from bug (missing update size of dest
file) in commit
1a980b8cbf00 ("ovl: add splice file read write helper")

The commit you want to backport fixes that problem, but introduces
another regression later fixed by commit
9b91b6b019fd ("ovl: fix deadlock in splice write")

So you'd need to backport both to end up with the correct
implementation of ovl_splice_write()

Thanks,
Amir.

       reply	other threads:[~2021-12-04  7:15 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CAMBWrQnfGuMjF6pQfoj9U5abKBQpaYtSH11QFo4+jZrL32XUEg@mail.gmail.com>
2021-12-04  7:15 ` Amir Goldstein [this message]
2021-12-04  7:25   ` overlay2: backporting a copy_file_range bug fix in Linux 5.6 to 5.10? Stan Hu

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