Messages in this thread | | | Date | Fri, 18 Aug 2006 02:50:29 -0600 | From | Andreas Dilger <> | Subject | Re: [Ext2-devel] [PATCH] fix ext3 mounts at 16T |
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On Aug 11, 2006 15:29 -0700, Mingming Cao wrote: > On Fri, 2006-08-11 at 17:13 -0500, Eric Sandeen wrote: > > I figure before we get too fired up about 48 bits and ext4 let's fix 32 bits on ext3 :) > > > > I need to do some actual IO testing now, but this gets things mounting for a 16T ext3 filesystem. > > (patched up e2fsprogs is needed too, I'll send that off the kernel list) > > > > This patch fixes these issues in the kernel: > > > > o sbi->s_groups_count overflows in ext3_fill_super() > > > > sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) - > > le32_to_cpu(es->s_first_data_block) + > > EXT3_BLOCKS_PER_GROUP(sb) - 1) / > > EXT3_BLOCKS_PER_GROUP(sb); > > > > at 16T, s_blocks_count is already maxed out; adding EXT3_BLOCKS_PER_GROUP(sb) overflows it and > > groups_count comes out to 0. Not really what we want, and causes a failed mount. > > > > Feel free to check my math (actually, please do!), but changing it this way should work & > > avoid the overflow: > > > > (A + B - 1)/B changed to: ((A - 1)/B) + 1 > > > > o ext3_check_descriptors() overflows range checks
This is generally not safe because of underflow, but it also isn't possible to have a 0-block filesystem so it should be OK.
Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.
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