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Commit 605fef0e authored by Paul Lawrence's avatar Paul Lawrence
Browse files

Improved libdm and dmctl to handle very large numbers of extents 

Enables performance testing with very large numbers of dm-linear devices

Test: Can create device with 16384 extents, and can get its table
Bug: 123261135
Change-Id: I0e78a659eb7616e4db6a8276031e25a0d84f52ba
parent c8b83f38

fs_mgr/libdm/dm.cpp

+18 −17
Original line number Diff line number Diff line
@@ -299,24 +299,25 @@ bool DeviceMapper::GetTableInfo(const std::string& name, std::vector<TargetInfo> 
// private methods of DeviceMapper

bool DeviceMapper::GetTable(const std::string& name, uint32_t flags,

                            std::vector<TargetInfo>* table) {

    char buffer[4096];

    struct dm_ioctl* io = reinterpret_cast<struct dm_ioctl*>(buffer);

    std::vector<char> buffer;

    struct dm_ioctl* io = nullptr;



    for (buffer.resize(4096);; buffer.resize(buffer.size() * 2)) {

        io = reinterpret_cast<struct dm_ioctl*>(&buffer[0]);



        InitIo(io, name);

    io->data_size = sizeof(buffer);

        io->data_size = buffer.size();

        io->data_start = sizeof(*io);

        io->flags = flags;

        if (ioctl(fd_, DM_TABLE_STATUS, io) < 0) {

            PLOG(ERROR) << "DM_TABLE_STATUS failed for " << name;

            return false;

        }

    if (io->flags & DM_BUFFER_FULL_FLAG) {

        PLOG(ERROR) << "DM_TABLE_STATUS result for " << name << " was too large";

        return false;

        if (!(io->flags & DM_BUFFER_FULL_FLAG)) break;

    }



    uint32_t cursor = io->data_start;

    uint32_t data_end = std::min(io->data_size, uint32_t(sizeof(buffer)));

    uint32_t data_end = std::min(io->data_size, uint32_t(buffer.size()));

    for (uint32_t i = 0; i < io->target_count; i++) {

        if (cursor + sizeof(struct dm_target_spec) > data_end) {

            break;
@@ -324,14 +325,14 @@ bool DeviceMapper::GetTable(const std::string& name, uint32_t flags, 
        // After each dm_target_spec is a status string. spec->next is an

        // offset from |io->data_start|, and we clamp it to the size of our

        // buffer.

        struct dm_target_spec* spec = reinterpret_cast<struct dm_target_spec*>(buffer + cursor);

        struct dm_target_spec* spec = reinterpret_cast<struct dm_target_spec*>(&buffer[cursor]);

        uint32_t data_offset = cursor + sizeof(dm_target_spec);

        uint32_t next_cursor = std::min(io->data_start + spec->next, data_end);



        std::string data;

        if (next_cursor > data_offset) {

            // Note: we use c_str() to eliminate any extra trailing 0s.

            data = std::string(buffer + data_offset, next_cursor - data_offset).c_str();

            data = std::string(&buffer[data_offset], next_cursor - data_offset).c_str();

        }

        table->emplace_back(*spec, data);

        cursor = next_cursor;

fs_mgr/tools/dmctl.cpp

+32 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <android-base/unique_fd.h>

#include <libdm/dm.h>



#include <fstream>

#include <functional>

#include <iomanip>

#include <ios>
@@ -50,6 +51,7 @@ using DmBlockDevice = ::android::dm::DeviceMapper::DmBlockDevice; 


static int Usage(void) {

    std::cerr << "usage: dmctl <command> [command options]" << std::endl;

    std::cerr << "       dmctl -f file" << std::endl;

    std::cerr << "commands:" << std::endl;

    std::cerr << "  create <dm-name> [-ro] <targets...>" << std::endl;

    std::cerr << "  delete <dm-name>" << std::endl;
@@ -58,6 +60,8 @@ static int Usage(void) { 
    std::cerr << "  table <dm-name>" << std::endl;

    std::cerr << "  help" << std::endl;

    std::cerr << std::endl;

    std::cerr << "-f file reads command and all parameters from named file" << std::endl;

    std::cerr << std::endl;

    std::cerr << "Target syntax:" << std::endl;

    std::cerr << "  <target_type> <start_sector> <num_sectors> [target_data]" << std::endl;

    return -EINVAL;
@@ -340,12 +344,40 @@ static std::map<std::string, std::function<int(int, char**)>> cmdmap = { 
        // clang-format on

};



static bool ReadFile(const char* filename, std::vector<std::string>* args,

                     std::vector<char*>* arg_ptrs) {

    std::ifstream file(filename);

    if (!file) return false;



    std::string arg;

    while (file >> arg) args->push_back(arg);



    for (auto const& i : *args) arg_ptrs->push_back(const_cast<char*>(i.c_str()));

    return true;

}



int main(int argc, char** argv) {

    android::base::InitLogging(argv, &android::base::StderrLogger);

    if (argc < 2) {

        return Usage();

    }



    std::vector<std::string> args;

    std::vector<char*> arg_ptrs;

    if (std::string("-f") == argv[1]) {

        if (argc != 3) {

            return Usage();

        }



        args.push_back(argv[0]);

        if (!ReadFile(argv[2], &args, &arg_ptrs)) {

            return Usage();

        }



        argc = arg_ptrs.size();

        argv = &arg_ptrs[0];

    }



    for (const auto& cmd : cmdmap) {

        if (cmd.first == argv[1]) {

            return cmd.second(argc - 2, argv + 2);