On Thu, Jun 07, 2012 at 12:27:56AM -0400, Ted Ts'o wrote:
> I think this patch should fix things. Could you give it a try (after
> re-enabling uninit_bg and then running e2fsck on the file systems)?
>
> Many thanks,
>
> - Ted
>
> commit b6b218940d47f20fc14e4d203930c575be0c65bf
> Author: Theodore Ts'o <tytso@xxxxxxx>
> Date: Thu Jun 7 00:26:56 2012 -0400
>
> ext4: fix the free blocks calculation for ext3 file systems w/ uninit_bg
>
> Ext3 filesystems that are converted to use as many ext4 file systems
> as possible
Just to clarify the description a bit:
Did you mean "..as many ext4 filesystem _features_ as possible" ?
> will enable uninit_bg to speed up e2fsck times. File
> systems with an native ext3 layout of inode tables and block
Perhaps "On file systems with a native ext3 layout..." ?
--D
> allocation bitmaps (as opposed to ext4's flex_bg layout), ext4 would
> sometimes incorrectly calculate the number of free blocks in an
> uninitialized block group. As a result, when first allocating a block
> in block group marked uninitalized, ext4 would incorrectly report that
> the file system was corrupt:
>
> EXT4-fs error (device dm-42): ext4_mb_generate_buddy:741: group 1699, 32254 clusters in bitmap, 32258 in gd
>
> Fix the calculation in ext4_num_overhead_clusters() to avoid this
> problem.
>
> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
>
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index 99b6324..cee7812 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -90,8 +90,8 @@ unsigned ext4_num_overhead_clusters(struct super_block *sb,
> * unusual file system layouts.
> */
> if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
> - block_cluster = EXT4_B2C(sbi, (start -
> - ext4_block_bitmap(sb, gdp)));
> + block_cluster = EXT4_B2C(sbi,
> + ext4_block_bitmap(sb, gdp) - start);
> if (block_cluster < num_clusters)
> block_cluster = -1;
> else if (block_cluster == num_clusters) {
> @@ -102,7 +102,7 @@ unsigned ext4_num_overhead_clusters(struct super_block *sb,
>
> if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
> inode_cluster = EXT4_B2C(sbi,
> - start - ext4_inode_bitmap(sb, gdp));
> + ext4_inode_bitmap(sb, gdp) - start);
> if (inode_cluster < num_clusters)
> inode_cluster = -1;
> else if (inode_cluster == num_clusters) {
> @@ -114,7 +114,7 @@ unsigned ext4_num_overhead_clusters(struct super_block *sb,
> itbl_blk = ext4_inode_table(sb, gdp);
> for (i = 0; i < sbi->s_itb_per_group; i++) {
> if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
> - c = EXT4_B2C(sbi, start - itbl_blk + i);
> + c = EXT4_B2C(sbi, itbl_blk + i - start);
> if ((c < num_clusters) || (c == inode_cluster) ||
> (c == block_cluster) || (c == itbl_cluster))
> continue;
>
> --
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>
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