df_blocks
free(df->df_blocks[i]);
free(df->df_blocks[i]);
free(df->df_blocks[i]);
df->df_blocks = erealloc(df->df_blocks,
df->df_blocks[i] = emalloc(DTFS_BLOCKSIZE);
memset(df->df_blocks[i], 0, DTFS_BLOCKSIZE);
src = df->df_blocks[BLOCKNUM(offset, DTFS_BLOCKSHIFT)]
dest = df->df_blocks[i]