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Commit c8edf84d authored by David Anderson's avatar David Anderson
Browse files

init: Add first-stage init support for snapshot-based partitions. 

Note that /metadata must now be mounted before CreateLogicalPartitions()
is called. This is because SnapshotManager overrides the default
partitioning scheme, and the only way to tell if a SnapshotManager is
needed is via the metadata partition.

Bug: 139204329
Test: manual test
Change-Id: I812df6c4c0d4d8753b1516f63dc70c5bc3e1c09c
parent 251ec05f

init/Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ cc_defaults { 
        "libprotobuf-cpp-lite",

        "libpropertyinfoserializer",

        "libpropertyinfoparser",

        "libsnapshot_nobinder",

    ],

    shared_libs: [

        "libbacktrace",

init/Android.mk

+1 −0
Original line number Diff line number Diff line
@@ -114,6 +114,7 @@ LOCAL_STATIC_LIBRARIES := \ 
    libbacktrace \

    libmodprobe \

    libext2_uuid \

    libsnapshot_nobinder \



LOCAL_SANITIZE := signed-integer-overflow

# First stage init is weird: it may start without stdout/stderr, and no /proc.

init/first_stage_mount.cpp

+24 −10
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <fs_mgr_overlayfs.h>

#include <libgsi/libgsi.h>

#include <liblp/liblp.h>

#include <libsnapshot/snapshot.h>



#include "devices.h"

#include "switch_root.h"
@@ -55,6 +56,7 @@ using android::fs_mgr::FstabEntry; 
using android::fs_mgr::ReadDefaultFstab;

using android::fs_mgr::ReadFstabFromDt;

using android::fs_mgr::SkipMountingPartitions;

using android::snapshot::SnapshotManager;



using namespace std::literals;
@@ -244,8 +246,6 @@ bool FirstStageMount::DoFirstStageMount() { 


    if (!InitDevices()) return false;



    if (!CreateLogicalPartitions()) return false;



    if (!MountPartitions()) return false;



    return true;
@@ -366,6 +366,16 @@ bool FirstStageMount::CreateLogicalPartitions() { 
        return false;

    }



    if (SnapshotManager::IsSnapshotManagerNeeded()) {

        auto sm = SnapshotManager::NewForFirstStageMount();

        if (!sm) {

            return false;

        }

        if (sm->NeedSnapshotsInFirstStageMount()) {

            return sm->CreateLogicalAndSnapshotPartitions(lp_metadata_partition_);

        }

    }



    auto metadata = android::fs_mgr::ReadCurrentMetadata(lp_metadata_partition_);

    if (!metadata) {

        LOG(ERROR) << "Could not read logical partition metadata from " << lp_metadata_partition_;
@@ -493,14 +503,7 @@ bool FirstStageMount::MountPartition(const Fstab::iterator& begin, bool erase_sa 
// this case, we mount system first then pivot to it.  From that point on,

// we are effectively identical to a system-as-root device.

bool FirstStageMount::TrySwitchSystemAsRoot() {

    auto metadata_partition = std::find_if(fstab_.begin(), fstab_.end(), [](const auto& entry) {

        return entry.mount_point == "/metadata";

    });

    if (metadata_partition != fstab_.end()) {

        if (MountPartition(metadata_partition, true /* erase_same_mounts */)) {

    UseGsiIfPresent();

        }

    }



    auto system_partition = std::find_if(fstab_.begin(), fstab_.end(), [](const auto& entry) {

        return entry.mount_point == "/system";
@@ -523,6 +526,17 @@ bool FirstStageMount::TrySwitchSystemAsRoot() { 
}



bool FirstStageMount::MountPartitions() {

    // Mount /metadata before creating logical partitions, since we need to

    // know whether a snapshot merge is in progress.

    auto metadata_partition = std::find_if(fstab_.begin(), fstab_.end(), [](const auto& entry) {

        return entry.mount_point == "/metadata";

    });

    if (metadata_partition != fstab_.end()) {

        MountPartition(metadata_partition, true /* erase_same_mounts */);

    }



    if (!CreateLogicalPartitions()) return false;



    if (!TrySwitchSystemAsRoot()) return false;



    if (!SkipMountingPartitions(&fstab_)) return false;