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 + <whatever> to an ext4_fsblk_t > > avoids 64-bit divides & modulos, and... > > fixes up any related formats > > Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx> You can add a "Signed-off-by: Andreas Dilger <adilger@xxxxxxx>" too. The revised calcs look good to me. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
