From: Arnd Bergmann Subject: Re: [RFC 4/5] MMC: Adjust unaligned write accesses. Date: Mon, 21 Mar 2011 20:05:37 +0100 Message-ID: <201103212005.37108.arnd@arndb.de> References: <1299718449-15172-1-git-send-email-andreiw@motorola.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Andrei Warkentin , linux-mmc@vger.kernel.org, linux-ext4@vger.kernel.org To: Andreas Dilger Return-path: In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Monday 21 March 2011 19:03:09 Andreas Dilger wrote: > Note that mballoc was specifically designed to handle allocation > requests that are aligned on RAID stripe boundaries, so it should > be able to handle this for MMC as well. What is needed is to tell > the filesystem what the underlying alignment is. That can be done > at format time with mke2fs or afterward with tune2fs by using the > "-E stripe_width" option. Ah, that sounds useful. So would I set the stripe_width to the erase block size, and the block group size to a multiple of that? Does this also work in (rare) cases where the erase block size is not a power of two? Arnd