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Commit 120f6b26 authored by Jaegeuk Kim's avatar Jaegeuk Kim
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Init: add dev.mnt.blk.bootdevice to access device sysfs 



This patch adds a new property, 'dev.mnt.root.<mount_point>', which provides,
for example of /data,

1. dm-N
  dev.mnt.dev.data = dm-N
  dev.mnt.blk.data = sdaN or mmcblk0pN
  dev.mnt.rootdisk.data = sda or mmcblk0

2. sdaN or mmcblk0pN
  dev.mnt.dev.data = sdaN or mmcblk0pN
  dev.mnt.blk.data = sdaN or mmcblk0pN
  dev.mnt.rootdisk.data = sda or mmcblk0

Signed-off-by: default avatarJaegeuk Kim <jaegeuk@google.com>
Change-Id: I0a58a62d416f966f26b5de04112c2f9a7eceb22c
parent 491004bb

init/README.md

+10 −5
Original line number Diff line number Diff line
@@ -804,13 +804,18 @@ Init provides state information with the following properties. 
`init.svc.<name>`

> State of a named service ("stopped", "stopping", "running", "restarting")



`dev.mnt.blk.<mount_point>`

`dev.mnt.dev.<mount_point>`, `dev.mnt.blk.<mount_point>`, `dev.mnt.rootdisk.<mount_point>`

> Block device base name associated with a *mount_point*.

  The *mount_point* has / replaced by . and if referencing the root mount point

  "/", it will use "/root", specifically `dev.mnt.blk.root`.

  Meant for references to `/sys/device/block/${dev.mnt.blk.<mount_point>}/` and

  `/sys/fs/ext4/${dev.mnt.blk.<mount_point>}/` to tune the block device

  characteristics in a device agnostic manner.

  "/", it will use "/root".

  `dev.mnt.dev.<mount_point>` indicates a block device attached to filesystems.

    (e.g., dm-N or sdaN/mmcblk0pN to access `/sys/fs/ext4/${dev.mnt.dev.<mount_point>}/`)



  `dev.mnt.blk.<mount_point>` indicates the disk partition to the above block device.

    (e.g., sdaN / mmcblk0pN to access `/sys/class/block/${dev.mnt.blk.<mount_point>}/`)



  `dev.mnt.rootdisk.<mount_point>` indicates the root disk to contain the above disk partition.

    (e.g., sda / mmcblk0 to access `/sys/class/block/${dev.mnt.rootdisk.<mount_point>}/queue`)



Init responds to properties that begin with `ctl.`.  These properties take the format of

`ctl.[<target>_]<command>` and the _value_ of the system property is used as a parameter.  The

init/mount_handler.cpp

+45 −13
Original line number Diff line number Diff line
@@ -72,8 +72,25 @@ MountHandlerEntry ParseMount(const std::string& line) { 
    return MountHandlerEntry(fields[0], fields[1], fields[2]);

}



// return dm-4 or dm-8 for dm-4, sda for sda25, or mmcblk0 for mmcblk0p24

// return sda25 for dm-4, sda25 for sda25, or mmcblk0p24 for mmcblk0p24

std::string GetDiskPart(std::string blockdev) {

    if (blockdev.find('/') != std::string::npos) return {};



    while (android::base::StartsWith(blockdev, "dm-")) {

        auto& dm = dm::DeviceMapper::Instance();

        std::optional<std::string> parent = dm.GetParentBlockDeviceByPath("/dev/block/" + blockdev);

        if (parent) {

            blockdev = android::base::Basename(*parent);

        } else {

            return {};

        }

    }

    return blockdev;

}



// return sda for sda25, or mmcblk0 for mmcblk0p24

std::string GetRootDisk(std::string blockdev) {

    if (blockdev.empty()) return {};

    if (blockdev.find('/') != std::string::npos) return {};



    std::error_code ec;
@@ -83,7 +100,6 @@ std::string GetRootDisk(std::string blockdev) { 
            return Basename(path);

        }

    }

    if (android::base::StartsWith(blockdev, "dm-")) return blockdev;

    return {};

}
@@ -91,31 +107,47 @@ void SetMountProperty(const MountHandlerEntry& entry, bool add) { 
    static constexpr char devblock[] = "/dev/block/";

    if (!android::base::StartsWith(entry.blk_device, devblock)) return;

    auto target = entry.blk_device.substr(strlen(devblock));

    std::string value;

    std::string diskpart, rootdisk;

    if (add) {

        value = GetRootDisk(target);

        diskpart = GetDiskPart(target);

        rootdisk = GetRootDisk(diskpart);



        struct stat sb;

        if (stat(entry.mount_point.c_str(), &sb) || !S_ISDIR(sb.st_mode)) value = "";

        if (stat(entry.mount_point.c_str(), &sb) || !S_ISDIR(sb.st_mode)) rootdisk = "";

        // Clear the noise associated with loopback and APEX.

        if (android::base::StartsWith(value, "loop")) value = "";

        if (android::base::StartsWith(entry.mount_point, "/apex/")) value = "";

        if (android::base::StartsWith(target, "loop")) rootdisk = "";

        if (android::base::StartsWith(entry.mount_point, "/apex/")) rootdisk = "";

    }

    auto mount_prop = entry.mount_point;

    if (mount_prop == "/") mount_prop = "/root";

    std::replace(mount_prop.begin(), mount_prop.end(), '/', '.');

    auto blk_mount_prop = "dev.mnt.blk" + mount_prop;

    auto dev_mount_prop = "dev.mnt.dev" + mount_prop;

    // Set property even if its value does not change to trigger 'on property:'

    auto rootdisk_mount_prop = "dev.mnt.rootdisk" + mount_prop;

    // Set property even if its rootdisk does not change to trigger 'on property:'

    // handling, except for clearing non-existent or already clear property.

    // Goal is reduction of empty properties and associated triggers.

    if (value.empty() && android::base::GetProperty(blk_mount_prop, "").empty()) return;

    android::base::SetProperty(blk_mount_prop, value);

    if (!value.empty()) {

        android::base::SetProperty(dev_mount_prop, target);

    } else {

    if (rootdisk.empty() && android::base::GetProperty(blk_mount_prop, "").empty()) return;



    if (rootdisk.empty()) {

        android::base::SetProperty(blk_mount_prop, "");

        android::base::SetProperty(dev_mount_prop, "");

    }

        android::base::SetProperty(rootdisk_mount_prop, "");

        return;

    }



    // 1. dm-N

    //  dev.mnt.dev.data = dm-N

    //  dev.mnt.blk.data = sdaN or mmcblk0pN

    //  dev.mnt.rootdisk.data = sda or mmcblk0

    //

    // 2. sdaN or mmcblk0pN

    //  dev.mnt.dev.data = sdaN or mmcblk0pN

    //  dev.mnt.blk.data = sdaN or mmcblk0pN

    //  dev.mnt.rootdisk.data = sda or mmcblk0

    android::base::SetProperty(dev_mount_prop, target);

    android::base::SetProperty(blk_mount_prop, diskpart);

    android::base::SetProperty(rootdisk_mount_prop, rootdisk);

}



}  // namespace

rootdir/init.rc

+5 −2
Original line number Diff line number Diff line
@@ -1085,9 +1085,11 @@ on boot 
    mkdir /dev/sys/fs/by-name 0755 system system

    symlink /sys/fs/f2fs/${dev.mnt.dev.data} /dev/sys/fs/by-name/userdata



    # to access dm-<num> sysfs

    # dev.mnt.dev.data=dm-N, dev.mnt.blk.data=sdaN/mmcblk0pN, dev.mnt.rootdisk.data=sda/mmcblk0, or

    # dev.mnt.dev.data=sdaN/mmcblk0pN, dev.mnt.blk.data=sdaN/mmcblk0pN, dev.mnt.rootdisk.data=sda/mmcblk0

    mkdir /dev/sys/block/by-name 0755 system system

    symlink /sys/class/block/${dev.mnt.dev.data} /dev/sys/block/by-name/userdata

    symlink /sys/class/block/${dev.mnt.rootdisk.data} /dev/sys/block/by-name/rootdisk



    # F2FS tuning. Set cp_interval larger than dirty_expire_centisecs, 30 secs,

    # to avoid power consumption when system becomes mostly idle. Be careful
@@ -1099,8 +1101,9 @@ on boot 


    # limit discard size to 128MB in order to avoid long IO latency

    # for filesystem tuning first (dm or sda)

    # Note that, if dm-<num> is used, sda/mmcblk0 should be tuned in vendor/init.rc

    # this requires enabling selinux entry for sda/mmcblk0 in vendor side

    write /dev/sys/block/by-name/userdata/queue/discard_max_bytes 134217728

    write /dev/sys/block/by-name/rootdisk/queue/discard_max_bytes 134217728



    # Permissions for System Server and daemons.

    chown system system /sys/power/autosleep