From: Chris Mason <chris.mason@oracle.com>
Date: Mon, 7 Mar 2011 16:10:24 +0000 (-0500)
Subject: Btrfs: deal with short returns from copy_from_user
X-Git-Tag: v2.6.38~13^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=31339acd07b4ba687906702085127895a56eb920;p=pandora-kernel.git

Btrfs: deal with short returns from copy_from_user

When copy_from_user is only able to copy some of the bytes we requested,
we may end up creating a partially up to date page.  To avoid garbage in
the page, we need to treat a partial copy as a zero length copy.

This makes the rest of the file_write code drop the page and
retry the whole copy instead of marking the partially up to
date page as dirty.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
cc: stable@kernel.org
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