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Commit 80281894 authored by Bowgo Tsai's avatar Bowgo Tsai
Browse files

first stage mount: support mount points like /vendor/abc 

Current syntax of the fstab in device tree (fstab_dt) assumes the
node name is the mount point, which doesn't allow subdir:

    vendor {   <== using "vendor/abc" leads to syntax error in device tree
        compatible = "android,vendor";
        dev = "/dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor";
        type = "ext4";
        mnt_flags = "ro,barrier=1,inode_readahead_blks=8";
        fsmgr_flags = "wait";
    };

This CL adds a new field "mnt_point" in the fstab_dt configuration:

    vendor_abc {
        compatible = "android,vendor_abc";
        dev = "/dev/block/platform/soc.0/f9824900.sdhci/by-name/abc";
        type = "ext4";
        mnt_flags = "ro,barrier=1,inode_readahead_blks=8";
        mnt_point = "/vendor/abc";                          <== new field
        fsmgr_flags = "wait";
    };

The new field is optional and will fallback to using node name as mount
point if it is absent.

Note that this CL also sorts fstab_dt by mount point, because
/vendor needs to be mounted first, which contains a directory
/vendor/abc, before /vendor/abc can be mounted.

Bug: 69955336
Test: first stage mount /vendor/abc on a device
Change-Id: Ie2e519f9801f211a7a221622f32c82bedd00353f
parent a7e2a12d

fs_mgr/Android.bp

+3 −0
Original line number Diff line number Diff line
@@ -25,6 +25,9 @@ cc_defaults { 
        "-Werror",

        "-Wno-unused-variable",

    ],

    cppflags: [

        "-std=gnu++1z",

    ],

}



cc_library_static {

fs_mgr/fs_mgr_fstab.cpp

+34 −16
Original line number Diff line number Diff line
@@ -23,6 +23,10 @@ 
#include <sys/mount.h>

#include <unistd.h>



#include <algorithm>

#include <utility>

#include <vector>



#include <android-base/file.h>

#include <android-base/stringprintf.h>

#include <android-base/strings.h>
@@ -397,16 +401,17 @@ static bool is_dt_fstab_compatible() { 
}



static std::string read_fstab_from_dt() {

    std::string fstab;

    if (!is_dt_compatible() || !is_dt_fstab_compatible()) {

        return fstab;

        return {};

    }



    std::string fstabdir_name = get_android_dt_dir() + "/fstab";

    std::unique_ptr<DIR, int (*)(DIR*)> fstabdir(opendir(fstabdir_name.c_str()), closedir);

    if (!fstabdir) return fstab;

    if (!fstabdir) return {};



    dirent* dp;

    // Each element in fstab_dt_entries is <mount point, the line format in fstab file>.

    std::vector<std::pair<std::string, std::string>> fstab_dt_entries;

    while ((dp = readdir(fstabdir.get())) != NULL) {

        // skip over name, compatible and .

        if (dp->d_type != DT_DIR || dp->d_name[0] == '.') continue;
@@ -427,41 +432,54 @@ static std::string read_fstab_from_dt() { 
        file_name = android::base::StringPrintf("%s/%s/dev", fstabdir_name.c_str(), dp->d_name);

        if (!read_dt_file(file_name, &value)) {

            LERROR << "dt_fstab: Failed to find device for partition " << dp->d_name;

            fstab.clear();

            break;

            return {};

        }

        fstab_entry.push_back(value);

        fstab_entry.push_back(android::base::StringPrintf("/%s", dp->d_name));



        std::string mount_point;

        file_name =

            android::base::StringPrintf("%s/%s/mnt_point", fstabdir_name.c_str(), dp->d_name);

        if (read_dt_file(file_name, &value)) {

            LINFO << "dt_fstab: Using a specified mount point " << value << " for " << dp->d_name;

            mount_point = value;

        } else {

            mount_point = android::base::StringPrintf("/%s", dp->d_name);

        }

        fstab_entry.push_back(mount_point);



        file_name = android::base::StringPrintf("%s/%s/type", fstabdir_name.c_str(), dp->d_name);

        if (!read_dt_file(file_name, &value)) {

            LERROR << "dt_fstab: Failed to find type for partition " << dp->d_name;

            fstab.clear();

            break;

            return {};

        }

        fstab_entry.push_back(value);



        file_name = android::base::StringPrintf("%s/%s/mnt_flags", fstabdir_name.c_str(), dp->d_name);

        if (!read_dt_file(file_name, &value)) {

            LERROR << "dt_fstab: Failed to find type for partition " << dp->d_name;

            fstab.clear();

            break;

            return {};

        }

        fstab_entry.push_back(value);



        file_name = android::base::StringPrintf("%s/%s/fsmgr_flags", fstabdir_name.c_str(), dp->d_name);

        if (!read_dt_file(file_name, &value)) {

            LERROR << "dt_fstab: Failed to find type for partition " << dp->d_name;

            fstab.clear();

            break;

            return {};

        }

        fstab_entry.push_back(value);



        fstab += android::base::Join(fstab_entry, " ");

        fstab += '\n';

        // Adds a fstab_entry to fstab_dt_entries, to be sorted by mount_point later.

        fstab_dt_entries.emplace_back(mount_point, android::base::Join(fstab_entry, " "));

    }



    return fstab;

    // Sort fstab_dt entries, to ensure /vendor is mounted before /vendor/abc is attempted.

    std::sort(fstab_dt_entries.begin(), fstab_dt_entries.end(),

              [](const auto& a, const auto& b) { return a.first < b.first; });



    std::string fstab_result;

    for (const auto& [_, dt_entry] : fstab_dt_entries) {

        fstab_result += dt_entry + "\n";

    }

    return fstab_result;

}



bool is_dt_compatible() {