On Fri 06-08-10 13:31:16, Lukas Czerner wrote:
...
> +/**
> + * ext4_trim_fs() -- trim ioctl handle function
> + * @sb: superblock for filesystem
> + * @start: First Byte to trim
> + * @len: number of Bytes to trim from start
> + * @minlen: minimum extent length in Bytes
> + *
> + * ext4_trim_fs goes through all allocation groups containing Bytes from
> + * start to start+len. For each such a group ext4_trim_all_free function
> + * is invoked to trim all free space.
> + */
> +int ext4_trim_fs(struct super_block *sb, uint64_t start, uint64_t len,
> + uint64_t minlen)
> +{
> + struct ext4_buddy e4b;
> + ext4_fsblk_t first_group, last_group;
> + ext4_group_t group, ngroups = ext4_get_groups_count(sb);
> + ext4_grpblk_t cnt, first_block, last_block;
> + struct ext4_super_block *es = EXT4_SB(sb)->s_es;
> + int ret = 0;
> +
> + start >>= sb->s_blocksize_bits;
> + len >>= sb->s_blocksize_bits;
> + minlen >>= sb->s_blocksize_bits;
> +
> + if (unlikely(minlen > EXT4_BLOCKS_PER_GROUP(sb)))
> + return -EINVAL;
> +
> + /* Determine first and last group to examine based on start and len */
> + first_group = (start - le32_to_cpu(es->s_first_data_block)) /
> + EXT4_BLOCKS_PER_GROUP(sb);
> + last_group = (start + len - le32_to_cpu(es->s_first_data_block)) /
> + EXT4_BLOCKS_PER_GROUP(sb);
> + last_group = (last_group > ngroups - 1) ? ngroups - 1 : last_group;
> +
> + if (first_group > last_group)
> + return -EINVAL;
> +
> + first_block = start % EXT4_BLOCKS_PER_GROUP(sb);
I think you should substract "le32_to_cpu(es->s_first_data_block)" from
the start before doing modulo.
Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
--
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
