Android storage mount configuration

1. Android storage mount configuration
1. # cat /init.rc

root@mv7420:/ # cat /init.rc | grep mount ….    # Create cgroup mount point for cpu accounting    mount cgroup none /acct cpuacct ….    # Create cgroup mount point for memory    mount tmpfs none /sys/fs/cgroup mode=0750,uid=0,gid=1000    mount cgroup none /sys/fs/cgroup/memory memory ….    # Secure container public mount points.    mount tmpfs tmpfs /mnt/asec mode=0755,gid=1000 ….    # Filesystem image public mount points.    mount tmpfs tmpfs /mnt/obb mode=0755,gid=1000 ….    # memory control cgroup    mount cgroup none /dev/memcg memory ….    # Create cgroup mount points for process groups    mount cgroup none /dev/cpuctl cpu ….    # pstore/ramoops previous console log    mount pstore pstore /sys/fs/pstore ….   # once everything is setup, no need to modify /    mount rootfs rootfs / ro remount    # mount shared so changes propagate into child namespaces    mount rootfs rootfs / shared rec ….

2. # cat /init.<device>.rc
   

root@mv7420:/ # cat init.samsungexynos7420.rc import init.samsungexynos7420.usb.rc on init    start watchdogd    chmod 0701 /mnt/media_rw    chown root root /mnt/media_rw …. …. service setup_fs /system/bin/setup_fs mmcblk0p3  mmcblk0p4    class core    user root    group root    oneshot service battery_charger /sbin/healthd -c        user root        group root        class charger        seclabel u:r:healthd:s0 on fs    mount_all /fstab.samsungexynos7420    setprop ro.crypto.fuse_sdcard true # Boost Block I/O Performance    write /sys/block/sda/queue/read_ahead_kb 512    write /sys/block/sda/queue/rq_affinity  2    write /sys/block/sda/queue/iosched/slice_idle 0 # Permissions for ION    chmod 0660 /sys/class/ion_cma/ion_video_ext/isolated    chown system system /sys/class/ion_cma/ion_video_ext/isolated # Permissions for backlight    chmod 0660 /sys/class/backlight/pwm-backlight.0/brightness    chown system system /sys/class/backlight/pwm-backlight.0/brightness # Copy DRM Key    copy /system/app/wv.keys /factory/wv.keys

3. External storage is managed by a combination of the vold init service and MountService system service. Mounting of physical external storage volumes is handled by vold, which performs staging operations to prepare the media before exposing it to apps.
   https://source.android.com/devices/storage/config.html
4. Android 4.2.2 and earlier : /etc/vold.fstab
5. Android 4.3 and later : /fstab.<device>
   the raw physical device must first be mounted /devices/xxx, then vold will manage the sdcard0, usb1, usb2
   # cat fstab.samsungexynos7420

# Android fstab file. #<src>                  <mnt_point>         <type>    <mnt_flags and options>                            <fs_mgr_flags> # The filesystem that contains the filesystem checker binary (typically /system) cannot # specify MF_CHECK, and must come before any filesystems that do specify MF_CHECK /dev/block/platform/15740000.dwmmc0/by-name/system      /system ext4    rowait /dev/block/platform/15740000.dwmmc0/by-name/cache       /cache  ext4    noatime, nosuid,nodev,nomblk_io_submit,errors=panic      wait /dev/block/platform/15740000.dwmmc0/by-name/userdata    /data   ext4    noatime, nosuid,nodev,nomblk_io_submit,discard,noauto_da_alloc,errors=panic    wait,force encrypt=/cache/metadata # VOLD /devices/15560000.dwmmc2/mmc_host/mmc2          auto            vfat    default voldmanaged=sdcard0:auto /devices/15510000.usb                           auto    vfat    default voldmana ged=usb1:auto /devices/15400000.usb/15400000.dwc3/xhci-hcd    auto    vfat    default voldmana ged=usb2:auto

2. MMC device partition name

# ls -l /dev/block/platform/15740000.dwmmc0/by-name/ lrwxrwxrwx root     root              2046-11-08 15:37 fat -> /dev/block/mmcblk0p1 lrwxrwxrwx root     root              2046-11-08 15:37 system -> /dev/block/mmcblk0p2 lrwxrwxrwx root     root              2046-11-08 15:37 userdata -> /dev/block/mmcblk0p3 lrwxrwxrwx root     root              2046-11-08 15:37 cache -> /dev/block/mmcblk0p4 lrwxrwxrwx root     root              2046-11-08 15:37 efs -> /dev/block/mmcblk0p5 lrwxrwxrwx root     root              2046-11-08 15:37 kernel -> /dev/block/mmcblk0p6 lrwxrwxrwx root     root              2046-11-08 15:37 ramdisk -> /dev/block/mmcblk0p7 lrwxrwxrwx root     root              2046-11-08 15:37 recovery -> /dev/block/mmcblk0p8 lrwxrwxrwx root     root              2046-11-08 15:37 dtb -> /dev/block/mmcblk0p9 lrwxrwxrwx root     root              2046-11-08 15:37 ldfw -> /dev/block/mmcblk0p10 lrwxrwxrwx root     root              2046-11-08 15:37 bootlogo -> /dev/block/mmcblk0p11 lrwxrwxrwx root     root              2046-11-08 15:37 font -> /dev/block/mmcblk0p12 lrwxrwxrwx root     root              2046-11-08 15:37 engmode -> /dev/block/mmcblk0p13

3. MMC device partition blocks

# cat /proc/partitions major minor  #blocks  name 179        0   30535680 mmcblk0 179        1         32 mmcblk0p1 179        2    2662400 mmcblk0p2 179        3   26941360 mmcblk0p3 179        4     819200 mmcblk0p4 179        5      10240 mmcblk0p5 179        6      20480 mmcblk0p6 179        7      26624 mmcblk0p7 259        0      26624 mmcblk0p8 259        1       1024 mmcblk0p9 259        2       2048 mmcblk0p10 259        3      10240 mmcblk0p11 259        4       1024 mmcblk0p12 259        5       2048 mmcblk0p13 179       24       4096 mmcblk0rpmb 179       16       4096 mmcblk0boot1 179        8       4096 mmcblk0boot0 254        0   26941360 dm-0

4. for MTD and EMMC devices, the  partition layout and name can be retrieved by reading /proc/mtd, /proc/emmc