Messages in this thread Patch in this message | | | Date | Fri, 11 Aug 2006 17:13:14 -0500 | From | Eric Sandeen <> | Subject | [PATCH] fix ext3 mounts at 16T |
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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
ext3_check_descriptors() iterates over all block groups making sure that various bits are within the right block ranges... on the last pass through, it is checking the error case
[item] >= block + EXT3_BLOCKS_PER_GROUP(sb)
where "block" is the first block in the last block group. The last block in this group (and the last one that will fit in 32 bits) is block + EXT3_BLOCKS_PER_GROUP(sb)- 1. block + EXT3_BLOCKS_PER_GROUP(sb) wraps back around to 0.
so, make things clearer with "first_block" and "last_block" where those are first and last, inclusive, and use <, > rather than <, >=.
Finally, the last block group may be smaller than the rest, so account for this on the last pass through: last_block = sb->s_blocks_count - 1;
(a similar patch could be done for ext2; does anyone in their right mind use ext2 at 16T? I'll send an ext2 patch doing the same thing if that's warranted)
Thanks,
-Eric
Signed-off-by: Eric Sandeen <esandeen@redhat.com>
Index: linux-2.6-xfs/fs/ext3/super.c =================================================================== --- linux-2.6-xfs.orig/fs/ext3/super.c +++ linux-2.6-xfs/fs/ext3/super.c @@ -1132,7 +1132,8 @@ static int ext3_setup_super(struct super static int ext3_check_descriptors (struct super_block * sb) { struct ext3_sb_info *sbi = EXT3_SB(sb); - ext3_fsblk_t block = le32_to_cpu(sbi->s_es->s_first_data_block); + ext3_fsblk_t first_block = le32_to_cpu(sbi->s_es->s_first_data_block); + ext3_fsblk_t last_block; struct ext3_group_desc * gdp = NULL; int desc_block = 0; int i; @@ -1141,12 +1142,16 @@ static int ext3_check_descriptors (struc for (i = 0; i < sbi->s_groups_count; i++) { + if (i == sbi->s_groups_count - 1) + last_block = sb->s_blocks_count - 1; + else + last = first + (EXT3_BLOCKS_PER_GROUP(sb) - 1); + if ((i % EXT3_DESC_PER_BLOCK(sb)) == 0) gdp = (struct ext3_group_desc *) sbi->s_group_desc[desc_block++]->b_data; - if (le32_to_cpu(gdp->bg_block_bitmap) < block || - le32_to_cpu(gdp->bg_block_bitmap) >= - block + EXT3_BLOCKS_PER_GROUP(sb)) + if (le32_to_cpu(gdp->bg_block_bitmap) < first_block || + le32_to_cpu(gdp->bg_block_bitmap) > last_block) { ext3_error (sb, "ext3_check_descriptors", "Block bitmap for group %d" @@ -1155,9 +1160,8 @@ static int ext3_check_descriptors (struc le32_to_cpu(gdp->bg_block_bitmap)); return 0; } - if (le32_to_cpu(gdp->bg_inode_bitmap) < block || - le32_to_cpu(gdp->bg_inode_bitmap) >= - block + EXT3_BLOCKS_PER_GROUP(sb)) + if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block || + le32_to_cpu(gdp->bg_inode_bitmap) > last_block) { ext3_error (sb, "ext3_check_descriptors", "Inode bitmap for group %d" @@ -1166,9 +1170,9 @@ static int ext3_check_descriptors (struc le32_to_cpu(gdp->bg_inode_bitmap)); return 0; } - if (le32_to_cpu(gdp->bg_inode_table) < block || - le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >= - block + EXT3_BLOCKS_PER_GROUP(sb)) + if (le32_to_cpu(gdp->bg_inode_table) < first_block || + le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group > + last_block) { ext3_error (sb, "ext3_check_descriptors", "Inode table for group %d" @@ -1177,7 +1181,7 @@ static int ext3_check_descriptors (struc le32_to_cpu(gdp->bg_inode_table)); return 0; } - block += EXT3_BLOCKS_PER_GROUP(sb); + first_block += EXT3_BLOCKS_PER_GROUP(sb); gdp++; } @@ -1580,10 +1584,9 @@ static int ext3_fill_super (struct super if (EXT3_BLOCKS_PER_GROUP(sb) == 0) goto cantfind_ext3; - 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); + sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) - + le32_to_cpu(es->s_first_data_block) - 1) + / EXT3_BLOCKS_PER_GROUP(sb)) + 1; db_count = (sbi->s_groups_count + EXT3_DESC_PER_BLOCK(sb) - 1) / EXT3_DESC_PER_BLOCK(sb); sbi->s_group_desc = kmalloc(db_count * sizeof (struct buffer_head *),
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