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Date:   Fri, 24 Apr 2020 03:11:53 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Ritesh Harjani <riteshh@linux.ibm.com>
Cc:     linux-ext4@vger.kernel.org, jack@suse.cz, tytso@mit.edu,
        adilger@dilger.ca, darrick.wong@oracle.com, hch@infradead.org,
        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>,
        Amir Goldstein <amir73il@gmail.com>,
        linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org
Subject: Re: [PATCH 0/5] ext4/overlayfs: fiemap related fixes
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I think the right fix is to move fiemap_check_ranges into all the ->fiemap
instances (we only have a few actual implementation minus the wrappers
around iomap/generic).  Then add a version if iomap_fiemap that can pass
in maxbytes explicitly for ext4, similar to what we've done with various
other generic helpers.

The idea of validating input against file systems specific paramaters
before we call into the fs is just bound to cause problems.