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From:   Amir Goldstein <amir73il@gmail.com>
Date:   Sat, 25 Apr 2020 13:49:43 +0300
Message-ID: <CAOQ4uxg2KOVBxqF400KW3VaQEaX4JGqfb_vCW=esTMkJqZWwvA@mail.gmail.com>
Subject: Re: [PATCH 0/5] ext4/overlayfs: fiemap related fixes
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Ritesh Harjani <riteshh@linux.ibm.com>,
        Ext4 <linux-ext4@vger.kernel.org>, Jan Kara <jack@suse.cz>,
        Theodore Tso <tytso@mit.edu>,
        Andreas Dilger <adilger@dilger.ca>,
        "Darrick J. Wong" <darrick.wong@oracle.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
        Murphy Zhou <jencce.kernel@gmail.com>,
        Miklos Szeredi <miklos@szeredi.hu>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        overlayfs <linux-unionfs@vger.kernel.org>
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On Sat, Apr 25, 2020 at 12:43 PM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Sat, Apr 25, 2020 at 12:11:59PM +0300, Amir Goldstein wrote:
> > FWIW, I agree with you.
> > And seems like Jan does as well, since he ACKed all your patches.
> > Current patches would be easier to backport to stable kernels.
>
> Honestly, the proper fix is pretty much trivial.  I wrote it up this
> morning over coffee:
>
>     http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/fiemap-fix
>
> Still needs more testing, though.

Very slick!

I still think Ritesh's patches are easier for backporting because they are
mostly contained within the ext4/overlayfs subsystems and your patch
can follow up as interface cleanup.

I would use as generic helper name generic_fiemap_checks()
akin to generic_write_checks() and generic_remap_file_range_prep() =>
generic_remap_checks().

Thanks,
Amir.