From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Subject: Re: [PATCH] UPDATED3: types fixup for mballoc Date: Tue, 8 Jan 2008 20:47:58 -0700 Message-ID: <20080109034757.GJ3351@webber.adilger.int> References: <473CCEB8.5060201@redhat.com> <473D2147.9030504@redhat.com> <477BEDAC.1030802@redhat.com> <20080103191733.GJ3351@webber.adilger.int> <477D3678.7020203@redhat.com> <477D4152.4020901@redhat.com> <4783D4E2.5080801@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ext4 development , Alex Tomas To: Eric Sandeen Return-path: Received: from mail.clusterfs.com ([74.0.229.162]:47334 "EHLO mail.clusterfs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752381AbYAIDsG (ORCPT ); Tue, 8 Jan 2008 22:48:06 -0500 Content-Disposition: inline In-Reply-To: <4783D4E2.5080801@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Jan 08, 2008 13:54 -0600, Eric Sandeen wrote: > Note, the calculations Andreas & I were discussing only work properly > for stripe <= blocks per group... I don't know if we'd need to enforce > that at mount time? I think that would be prudent, but can be done in a separate patch. If the RAID stripe width is so large that one has to do read-modify-write for a whole group write (8MB @ 1kB blocksize, 128MB @ 4kB blocksize) then I don't think we can use that to align allocations. I think Aneesh might be working on getting s_raid_stripe_width from the superblock, and we may as well do the sanity checking in the same patch. If sb->s_raid_stripe_width > EXT4_BLOCKS_PER_GROUP, then as a fallback I'd suggest using sb->s_raid_stride if < EXT4_BLOCKS_PER_GROUP, or just ignoring both if unsuitable. > I ran into a potential overflow in ext4_mb_scan_aligned, > and went looking for others in mballoc. This patch hits a > few spots, compile-tested only at this point, comments welcome. > > This patch: > > changes fe_len to an int, I don't think we need it to be a long, > looking at how it's used (should it be a grpblk_t?) Also change > anything assigned to return value of mb_find_extent, since it returns > fe_len. > > changes anything that does groupno * EXT4_BLOCKS_PER_GROUP > or pa->pa_pstart + to an ext4_fsblk_t > > avoids 64-bit divides & modulos, and... > > fixes up any related formats > > Signed-off-by: Eric Sandeen You can add a "Signed-off-by: Andreas Dilger " too. The revised calcs look good to me. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.