linux-ext4 - Re: [PATCH 3/4] libext2fs: fix block-mapped file punch

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Message-ID: <20151116120428.GC29432@thunk.org>
Date:	Mon, 16 Nov 2015 07:04:28 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Andreas Dilger <andreas.dilger@...el.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 3/4] libext2fs: fix block-mapped file punch

On Fri, Nov 13, 2015 at 06:10:28PM -0700, Andreas Dilger wrote:
> If ext2fs_punch() is called with "end = ~0U" (which is natural from
> a programming POV) it tries to compute "count" based on "start" and
> "end", but doesn't quite get it right.

You should make clear that this only applies in the case where we are
punching on an indirect block mapped file.  I read this and alarm
bells started going off since end is a blk64_t, and we can't do this
for extent-mapped files.

> Pass "count=~0"
> in this case, and also handle that explicitly in ext2_punch_ind().
> Since ext2_punch_ind() is itself a public function, so it makes
> sense to fix this in both places.

Um, ext2fs_punch()_ind is *not* a public function.

						- Ted
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