How to support dbp for dual boot slot devices?

[MlgmXyysd]

Device: OnePlus 6 All blocks have a & b suffix.

these are block infomation: basedir: /dev/block/bootdevice/by-name/ /dev/block/platform/soc/1d84000.ufshc/by-name/

All blocks symlink in basedir: ALIGN_TO_128K_1 -> /dev/block/sdd1 ALIGN_TO_128K_2 -> /dev/block/sdf1 ImageFv -> /dev/block/sde72 LOGO_a -> /dev/block/sde20 LOGO_b -> /dev/block/sde48 abl_a -> /dev/block/sde8 abl_b -> /dev/block/sde36 aop_a -> /dev/block/sde1 aop_b -> /dev/block/sde29 apdp -> /dev/block/sde63 bluetooth_a -> /dev/block/sde5 bluetooth_b -> /dev/block/sde33 boot_a -> /dev/block/sde11 boot_aging -> /dev/block/sde58 boot_b -> /dev/block/sde39 cdt -> /dev/block/sdd2 cmnlib64_a -> /dev/block/sde13 cmnlib64_b -> /dev/block/sde41 cmnlib_a -> /dev/block/sde12 cmnlib_b -> /dev/block/sde40 config -> /dev/block/sda12 ddr -> /dev/block/sdd3 devcfg_a -> /dev/block/sde14 devcfg_b -> /dev/block/sde42 devinfo -> /dev/block/sde61 dip -> /dev/block/sde62 dsp_a -> /dev/block/sde9 dsp_b -> /dev/block/sde37 dtbo_a -> /dev/block/sde18 dtbo_b -> /dev/block/sde46 frp -> /dev/block/sda6 fsc -> /dev/block/sdf5 fsg -> /dev/block/sdf4 fw_4j1ed_a -> /dev/block/sde21 fw_4j1ed_b -> /dev/block/sde49 fw_4u1ea_a -> /dev/block/sde22 fw_4u1ea_b -> /dev/block/sde50 fw_ufs3_a -> /dev/block/sde23 fw_ufs3_b -> /dev/block/sde51 fw_ufs4_a -> /dev/block/sde24 fw_ufs4_b -> /dev/block/sde52 fw_ufs5_a -> /dev/block/sde25 fw_ufs5_b -> /dev/block/sde53 fw_ufs6_a -> /dev/block/sde26 fw_ufs6_b -> /dev/block/sde54 fw_ufs7_a -> /dev/block/sde27 fw_ufs7_b -> /dev/block/sde55 fw_ufs8_a -> /dev/block/sde28 fw_ufs8_b -> /dev/block/sde56 hyp_a -> /dev/block/sde3 hyp_b -> /dev/block/sde31 keymaster_a -> /dev/block/sde10 keymaster_b -> /dev/block/sde38 keystore -> /dev/block/sda5 limits -> /dev/block/sde67 logdump -> /dev/block/sde71 logfs -> /dev/block/sde69 mdtp_a -> /dev/block/sde7 mdtp_b -> /dev/block/sde35 mdtpsecapp_a -> /dev/block/sde6 mdtpsecapp_b -> /dev/block/sde34 minidump -> /dev/block/sde57 misc -> /dev/block/sda3 modem_a -> /dev/block/sde4 modem_b -> /dev/block/sde32 modemst1 -> /dev/block/sdf2 modemst2 -> /dev/block/sdf3 msadp -> /dev/block/sde64 odm_a -> /dev/block/sda15 odm_b -> /dev/block/sda16 oem_dycnvbk -> /dev/block/sda8 oem_stanvbk -> /dev/block/sda9 op1 -> /dev/block/sde59 op2 -> /dev/block/sda7 param -> /dev/block/sda4 persist -> /dev/block/sda2 qupfw_a -> /dev/block/sde15 qupfw_b -> /dev/block/sde43 reserve1 -> /dev/block/sda10 reserve2 -> /dev/block/sda11 sec -> /dev/block/sde60 splash -> /dev/block/sde66 spunvm -> /dev/block/sde65 ssd -> /dev/block/sda1 sti -> /dev/block/sde70 storsec_a -> /dev/block/sde19 storsec_b -> /dev/block/sde47 system_a -> /dev/block/sda13 system_b -> /dev/block/sda14 toolsfv -> /dev/block/sde68 tz_a -> /dev/block/sde2 tz_b -> /dev/block/sde30 userdata -> /dev/block/sda17 vbmeta_a -> /dev/block/sde17 vbmeta_b -> /dev/block/sde45 vendor_a -> /dev/block/sde16 vendor_b -> /dev/block/sde44 xbl_a -> /dev/block/sdb1 xbl_b -> /dev/block/sdc1 xbl_config_a -> /dev/block/sdb2 xbl_config_b -> /dev/block/sdc2

[MlgmXyysd]

and recovery is in boot partitions, cache is in /data/cache. So it's havn't cache partitions.