fs_mgr: libdm: add support to create and delete device mapper devices.
Test: dmctl create system; dmctl delete system
Test: verify that ueventd creates /dev/block/dm-X and verify the dm
device name from /sys/block/dm-X/dm/name
Bug: 110035986
Change-Id: I2a08e2ea7007c0c13fe64d444f0d6618784edae7
Signed-off-by: Sandeep Patil <sspatil@google.com>
diff --git a/fs_mgr/libdm/dm.cpp b/fs_mgr/libdm/dm.cpp
index 9a2910e..c2f732b 100644
--- a/fs_mgr/libdm/dm.cpp
+++ b/fs_mgr/libdm/dm.cpp
@@ -22,6 +22,7 @@
#include <sys/types.h>
#include <unistd.h>
+#include <memory>
#include <string>
#include <vector>
@@ -39,14 +40,69 @@
return instance;
}
// Creates a new device mapper device
-bool DeviceMapper::CreateDevice(const std::string& /* name */) {
+bool DeviceMapper::CreateDevice(const std::string& name) {
+ if (name.empty()) {
+ LOG(ERROR) << "Unnamed device mapper device creation is not supported";
+ return false;
+ }
+
+ if (name.size() >= DM_NAME_LEN) {
+ LOG(ERROR) << "[" << name << "] is too long to be device mapper name";
+ return false;
+ }
+
+ std::unique_ptr<struct dm_ioctl, decltype(&free)> io(
+ static_cast<struct dm_ioctl*>(malloc(sizeof(struct dm_ioctl))), free);
+ if (io == nullptr) {
+ LOG(ERROR) << "Failed to allocate dm_ioctl";
+ return false;
+ }
+ InitIo(io.get(), name);
+
+ if (ioctl(fd_, DM_DEV_CREATE, io.get())) {
+ PLOG(ERROR) << "DM_DEV_CREATE failed to create [" << name << "]";
+ return false;
+ }
+
+ // Check to make sure the newly created device doesn't already have targets
+ // added or opened by someone
+ CHECK(io->target_count == 0) << "Unexpected targets for newly created [" << name << "] device";
+ CHECK(io->open_count == 0) << "Unexpected opens for newly created [" << name << "] device";
+
// Creates a new device mapper device with the name passed in
- return false;
+ return true;
}
-bool DeviceMapper::DeleteDevice(const std::string& /* name */) {
- // Destroy device here first
- return false;
+bool DeviceMapper::DeleteDevice(const std::string& name) {
+ if (name.empty()) {
+ LOG(ERROR) << "Unnamed device mapper device creation is not supported";
+ return false;
+ }
+
+ if (name.size() >= DM_NAME_LEN) {
+ LOG(ERROR) << "[" << name << "] is too long to be device mapper name";
+ return false;
+ }
+
+ std::unique_ptr<struct dm_ioctl, decltype(&free)> io(
+ static_cast<struct dm_ioctl*>(malloc(sizeof(struct dm_ioctl))), free);
+ if (io == nullptr) {
+ LOG(ERROR) << "Failed to allocate dm_ioctl";
+ return false;
+ }
+ InitIo(io.get(), name);
+
+ if (ioctl(fd_, DM_DEV_REMOVE, io.get())) {
+ PLOG(ERROR) << "DM_DEV_REMOVE failed to create [" << name << "]";
+ return false;
+ }
+
+ // Check to make sure appropriate uevent is generated so ueventd will
+ // do the right thing and remove the corresponding device node and symlinks.
+ CHECK(io->flags & DM_UEVENT_GENERATED_FLAG)
+ << "Didn't generate uevent for [" << name << "] removal";
+
+ return true;
}
const std::unique_ptr<DmTable> DeviceMapper::table(const std::string& /* name */) const {
@@ -82,12 +138,13 @@
return false;
}
+ // Sets appropriate data size and data_start to make sure we tell kernel
+ // about the total size of the buffer we are passing and where to start
+ // writing the list of targets.
struct dm_ioctl* io = reinterpret_cast<struct dm_ioctl*>(buffer.get());
- io->data_start = sizeof(*io);
+ InitIo(io);
io->data_size = data_size;
- io->version[0] = 4;
- io->version[1] = 0;
- io->version[2] = 0;
+ io->data_start = sizeof(*io);
if (ioctl(fd_, DM_LIST_VERSIONS, io)) {
PLOG(ERROR) << "Failed to get DM_LIST_VERSIONS from kernel";
@@ -131,5 +188,20 @@
return "";
}
+// private methods of DeviceMapper
+void DeviceMapper::InitIo(struct dm_ioctl* io, const std::string& name) const {
+ CHECK(io != nullptr) << "nullptr passed to dm_ioctl initialization";
+ memset(io, 0, sizeof(*io));
+
+ io->version[0] = DM_VERSION0;
+ io->version[1] = DM_VERSION1;
+ io->version[2] = DM_VERSION2;
+ io->data_size = sizeof(*io);
+ io->data_start = 0;
+ if (!name.empty()) {
+ strlcpy(io->name, name.c_str(), sizeof(io->name));
+ }
+}
+
} // namespace dm
} // namespace android
diff --git a/fs_mgr/libdm/include/dm.h b/fs_mgr/libdm/include/dm.h
index 0cd0149..d839393 100644
--- a/fs_mgr/libdm/include/dm.h
+++ b/fs_mgr/libdm/include/dm.h
@@ -19,6 +19,7 @@
#include <errno.h>
#include <fcntl.h>
+#include <linux/dm-ioctl.h>
#include <unistd.h>
#include <memory>
@@ -27,6 +28,11 @@
#include <dm_table.h>
+// The minimum expected device mapper major.minor version
+#define DM_VERSION0 (4)
+#define DM_VERSION1 (0)
+#define DM_VERSION2 (0)
+
#define DM_ALIGN_MASK (7)
#define DM_ALIGN(x) ((x + DM_ALIGN_MASK) & ~DM_ALIGN_MASK)
@@ -87,6 +93,8 @@
// a finite amount of memory. This limit is in no way enforced by the kernel.
static constexpr uint32_t kMaxPossibleDmTargets = 256;
+ void InitIo(struct dm_ioctl* io, const std::string& name = std::string()) const;
+
DeviceMapper() : fd_(-1) {
fd_ = TEMP_FAILURE_RETRY(open("/dev/device-mapper", O_RDWR | O_CLOEXEC));
if (fd_ < 0) {
diff --git a/fs_mgr/tools/dmctl.cpp b/fs_mgr/tools/dmctl.cpp
index 27e2a58..c123830 100644
--- a/fs_mgr/tools/dmctl.cpp
+++ b/fs_mgr/tools/dmctl.cpp
@@ -39,50 +39,46 @@
static int Usage(void) {
std::cerr << "usage: dmctl <command> [command options]";
std::cerr << "commands:";
- std::cerr << " create <dm-name> <dm-target> [-lo <filename>] <dm-target-args>";
- std::cerr, " delete <dm-device>";
+ std::cerr << " create <dm-name> [dm-target> [-lo <filename>] <dm-target-args>]";
+ std::cerr, " delete <dm-name>";
std::cerr, " list";
std::cerr, " help";
return -EINVAL;
}
static int DmCreateCmdHandler(int argc, char** argv) {
- if (argc <= 1) {
- std::cerr << "DmCreateCmdHandler: Invalid arguments";
- if (argc > 0) std::cerr << " args: " << argv[0];
+ if (argc < 1) {
+ std::cerr << "DmCreateCmdHandler: atleast 'name' MUST be provided for target device";
return -EINVAL;
}
- // Parse Everything first to make sure we have everything we need.
- std::string devname = argv[0];
+ std::string name = argv[0];
DeviceMapper& dm = DeviceMapper::Instance();
- std::vector<DmTarget> targets;
- if (!dm.GetAvailableTargets(&targets)) {
- std::cerr << "Failed to read available device mapper targets";
- return -errno;
+ if (!dm.CreateDevice(name)) {
+ std::cerr << "DmCreateCmdHandler: Failed to create " << name << " device";
+ return -EIO;
}
- if (targets.empty()) {
- std::cerr << "zero device mapper targets available";
- return -EEXIST;
+ // if we also have target specified
+ if (argc > 1) {
+ // fall through for now. This will eventually create a DmTarget() based on the target name
+ // passing it the table that is specified at the command line
}
- for (const auto& target : targets) {
- if (target.name() == argv[1]) {
- // TODO(b/110035986) : Create the target here, return success for now.
- return 0;
- }
- }
-
- std::cerr << "Invalid or non-existing target : " << argv[1];
- return -EINVAL;
+ return 0;
}
static int DmDeleteCmdHandler(int argc, char** argv) {
- std::cout << "DmDeleteCmdHandler:" << std::endl;
- std::cout << " args:" << std::endl;
- for (int i = 0; i < argc; i++) {
- std::cout << " " << argv[i] << std::endl;
+ if (argc < 1) {
+ std::cerr << "DmCreateCmdHandler: atleast 'name' MUST be provided for target device";
+ return -EINVAL;
+ }
+
+ std::string name = argv[0];
+ DeviceMapper& dm = DeviceMapper::Instance();
+ if (!dm.DeleteDevice(name)) {
+ std::cerr << "DmCreateCmdHandler: Failed to create " << name << " device";
+ return -EIO;
}
return 0;
@@ -94,7 +90,7 @@
DeviceMapper& dm = DeviceMapper::Instance();
std::vector<DmTarget> targets;
if (!dm.GetAvailableTargets(&targets)) {
- std::cerr << "Failed to read available device mapper targets";
+ std::cerr << "Failed to read available device mapper targets" << std::endl;
return -errno;
}