Support sysfs changes in the Linux 5.15 kernel.

DM_DEV_CREATE no longer creates sysfs nodes. Note this in ueventd and
add some helper APIs to libdm, so devices can be created with a
placeholder table.

This also fixes a bug in dmctl where the detailed info on suspended
devices was wrong.

Bug: 259328366
CRs-Fixed: 3312045
Test: dmctl with "uevents" tool
Change-Id: I822f8010e48d32841aa0ee508822f76d03a3dd85
(cherry picked from commit d6bf86b8cf12ac50c9bc8ddaa6a33d6ee67ab91f)

8 files changed, 100 insertions, 25 deletions

diff --git a/fs_mgr/libdm/dm.cpp b/fs_mgr/libdm/dm.cpp
index 4b906a22e..deffae1ad 100644
--- a/fs_mgr/libdm/dm.cpp
+++ b/fs_mgr/libdm/dm.cpp
@@ -290,7 +290,7 @@ bool DeviceMapper::CreateDevice(const std::string& name, const DmTable& table) {
     return true;
 }
 
-bool DeviceMapper::LoadTableAndActivate(const std::string& name, const DmTable& table) {
+bool DeviceMapper::LoadTable(const std::string& name, const DmTable& table) {
     std::string ioctl_buffer(sizeof(struct dm_ioctl), 0);
     ioctl_buffer += table.Serialize();
 
@@ -306,9 +306,17 @@ bool DeviceMapper::LoadTableAndActivate(const std::string& name, const DmTable&
         PLOG(ERROR) << "DM_TABLE_LOAD failed";
         return false;
     }
+    return true;
+}
 
-    InitIo(io, name);
-    if (ioctl(fd_, DM_DEV_SUSPEND, io)) {
+bool DeviceMapper::LoadTableAndActivate(const std::string& name, const DmTable& table) {
+    if (!LoadTable(name, table)) {
+        return false;
+    }
+
+    struct dm_ioctl io;
+    InitIo(&io, name);
+    if (ioctl(fd_, DM_DEV_SUSPEND, &io)) {
         PLOG(ERROR) << "DM_TABLE_SUSPEND resume failed";
         return false;
     }
diff --git a/fs_mgr/libdm/dm_test.cpp b/fs_mgr/libdm/dm_test.cpp
index 541f254cb..4448d35c5 100644
--- a/fs_mgr/libdm/dm_test.cpp
+++ b/fs_mgr/libdm/dm_test.cpp
@@ -690,3 +690,23 @@ TEST(libdm, CreateEmptyDevice) {
     // Empty device should be in suspended state.
     ASSERT_EQ(DmDeviceState::SUSPENDED, dm.GetState("empty-device"));
 }
+
+TEST(libdm, UeventAfterLoadTable) {
+    static const char* kDeviceName = "libmd-test-uevent-load-table";
+
+    DeviceMapper& dm = DeviceMapper::Instance();
+    ASSERT_TRUE(dm.CreateEmptyDevice(kDeviceName));
+
+    DmTable table;
+    table.Emplace<DmTargetError>(0, 1);
+    ASSERT_TRUE(dm.LoadTable(kDeviceName, table));
+
+    std::string ignore_path;
+    ASSERT_TRUE(dm.WaitForDevice(kDeviceName, 5s, &ignore_path));
+
+    auto info = dm.GetDetailedInfo(kDeviceName);
+    ASSERT_TRUE(info.has_value());
+    ASSERT_TRUE(info->IsSuspended());
+
+    ASSERT_TRUE(dm.DeleteDevice(kDeviceName));
+}
diff --git a/fs_mgr/libdm/include/libdm/dm.h b/fs_mgr/libdm/include/libdm/dm.h
index 0a3e8d2bd..dbef8f902 100644
--- a/fs_mgr/libdm/include/libdm/dm.h
+++ b/fs_mgr/libdm/include/libdm/dm.h
@@ -75,6 +75,7 @@ class IDeviceMapper {
                               const std::chrono::milliseconds& timeout_ms) = 0;
     virtual DmDeviceState GetState(const std::string& name) const = 0;
     virtual bool LoadTableAndActivate(const std::string& name, const DmTable& table) = 0;
+    virtual bool LoadTable(const std::string& name, const DmTable& table) = 0;
     virtual bool GetTableInfo(const std::string& name, std::vector<TargetInfo>* table) = 0;
     virtual bool GetTableStatus(const std::string& name, std::vector<TargetInfo>* table) = 0;
     virtual bool GetDmDevicePathByName(const std::string& name, std::string* path) = 0;
@@ -116,7 +117,7 @@ class DeviceMapper final : public IDeviceMapper {
         bool IsBufferFull() const { return flags_ & DM_BUFFER_FULL_FLAG; }
         bool IsInactiveTablePresent() const { return flags_ & DM_INACTIVE_PRESENT_FLAG; }
         bool IsReadOnly() const { return flags_ & DM_READONLY_FLAG; }
-        bool IsSuspended() const { return flags_ & DM_SUSPEND_FLAG; }
+        bool IsSuspended() const { return !IsActiveTablePresent() || (flags_ & DM_SUSPEND_FLAG); }
     };
 
     // Removes a device mapper device with the given name.
@@ -199,6 +200,12 @@ class DeviceMapper final : public IDeviceMapper {
     // Returns 'true' on success, false otherwise.
     bool LoadTableAndActivate(const std::string& name, const DmTable& table) override;
 
+    // Same as LoadTableAndActivate, but there is no resume step. This puts the
+    // new table in the inactive slot.
+    //
+    // Returns 'true' on success, false otherwise.
+    bool LoadTable(const std::string& name, const DmTable& table) override;
+
     // Returns true if a list of available device mapper targets registered in the kernel was
     // successfully read and stored in 'targets'. Returns 'false' otherwise.
     bool GetAvailableTargets(std::vector<DmTargetTypeInfo>* targets);
diff --git a/fs_mgr/libdm/include/libdm/dm_table.h b/fs_mgr/libdm/include/libdm/dm_table.h
index ee66653a5..427f34dea 100644
--- a/fs_mgr/libdm/include/libdm/dm_table.h
+++ b/fs_mgr/libdm/include/libdm/dm_table.h
@@ -31,6 +31,7 @@ namespace dm {
 class DmTable {
   public:
     DmTable() : num_sectors_(0), readonly_(false) {}
+    DmTable(DmTable&& other) = default;
 
     // Adds a target to the device mapper table for a range specified in the target object.
     // The function will return 'true' if the target was successfully added and doesn't overlap with
@@ -70,6 +71,8 @@ class DmTable {
     void set_readonly(bool readonly) { readonly_ = readonly; }
     bool readonly() const { return readonly_; }
 
+    DmTable& operator=(DmTable&& other) = default;
+
     ~DmTable() = default;
 
   private:
diff --git a/fs_mgr/libdm/include/libdm/dm_target.h b/fs_mgr/libdm/include/libdm/dm_target.h
index 954305816..09fe20012 100644
--- a/fs_mgr/libdm/include/libdm/dm_target.h
+++ b/fs_mgr/libdm/include/libdm/dm_target.h
@@ -323,6 +323,14 @@ class DmTargetUser final : public DmTarget {
     std::string control_device_;
 };
 
+class DmTargetError final : public DmTarget {
+  public:
+    DmTargetError(uint64_t start, uint64_t length) : DmTarget(start, length) {}
+
+    std::string name() const override { return "error"; }
+    std::string GetParameterString() const override { return ""; }
+};
+
 }  // namespace dm
 }  // namespace android
 
diff --git a/fs_mgr/libsnapshot/include_test/libsnapshot/test_helpers.h b/fs_mgr/libsnapshot/include_test/libsnapshot/test_helpers.h
index c3b40dca4..1de6d9835 100644
--- a/fs_mgr/libsnapshot/include_test/libsnapshot/test_helpers.h
+++ b/fs_mgr/libsnapshot/include_test/libsnapshot/test_helpers.h
@@ -143,6 +143,9 @@ class DeviceMapperWrapper : public android::dm::IDeviceMapper {
     virtual DmDeviceState GetState(const std::string& name) const override {
         return impl_.GetState(name);
     }
+    virtual bool LoadTable(const std::string& name, const DmTable& table) {
+        return impl_.LoadTable(name, table);
+    }
     virtual bool LoadTableAndActivate(const std::string& name, const DmTable& table) {
         return impl_.LoadTableAndActivate(name, table);
     }
diff --git a/fs_mgr/tools/dmctl.cpp b/fs_mgr/tools/dmctl.cpp
index 62ca1620b..10efd0cab 100644
--- a/fs_mgr/tools/dmctl.cpp
+++ b/fs_mgr/tools/dmctl.cpp
@@ -33,6 +33,7 @@
 #include <ios>
 #include <iostream>
 #include <map>
+#include <optional>
 #include <sstream>
 #include <string>
 #include <vector>
@@ -183,6 +184,8 @@ class TargetParser final {
             }
             std::string control_device = NextArg();
             return std::make_unique<DmTargetUser>(start_sector, num_sectors, control_device);
+        } else if (target_type == "error") {
+            return std::make_unique<DmTargetError>(start_sector, num_sectors);
         } else {
             std::cerr << "Unrecognized target type: " << target_type << std::endl;
             return nullptr;
@@ -206,16 +209,26 @@ class TargetParser final {
     char** argv_;
 };
 
-static bool parse_table_args(DmTable* table, int argc, char** argv) {
+struct TableArgs {
+    DmTable table;
+    bool suspended = false;
+};
+
+static std::optional<TableArgs> parse_table_args(int argc, char** argv) {
+    TableArgs out;
+
     // Parse extended options first.
     int arg_index = 1;
     while (arg_index < argc && argv[arg_index][0] == '-') {
         if (strcmp(argv[arg_index], "-ro") == 0) {
-            table->set_readonly(true);
+            out.table.set_readonly(true);
+            arg_index++;
+        } else if (strcmp(argv[arg_index], "-suspended") == 0) {
+            out.suspended = true;
             arg_index++;
         } else {
             std::cerr << "Unrecognized option: " << argv[arg_index] << std::endl;
-            return -EINVAL;
+            return {};
         }
     }
 
@@ -223,37 +236,44 @@ static bool parse_table_args(DmTable* table, int argc, char** argv) {
     TargetParser parser(argc - arg_index, argv + arg_index);
     while (parser.More()) {
         std::unique_ptr<DmTarget> target = parser.Next();
-        if (!target || !table->AddTarget(std::move(target))) {
-            return -EINVAL;
+        if (!target || !out.table.AddTarget(std::move(target))) {
+            return {};
         }
     }
 
-    if (table->num_targets() == 0) {
+    if (out.table.num_targets() == 0) {
         std::cerr << "Must define at least one target." << std::endl;
-        return -EINVAL;
+        return {};
     }
-    return 0;
+    return {std::move(out)};
 }
 
 static int DmCreateCmdHandler(int argc, char** argv) {
     if (argc < 1) {
-        std::cerr << "Usage: dmctl create <dm-name> [-ro] <targets...>" << std::endl;
+        std::cerr << "Usage: dmctl create <dm-name> [--suspended] [-ro] <targets...>" << std::endl;
         return -EINVAL;
     }
     std::string name = argv[0];
 
-    DmTable table;
-    int ret = parse_table_args(&table, argc, argv);
-    if (ret) {
-        return ret;
+    auto table_args = parse_table_args(argc, argv);
+    if (!table_args) {
+        return -EINVAL;
     }
 
     std::string ignore_path;
     DeviceMapper& dm = DeviceMapper::Instance();
-    if (!dm.CreateDevice(name, table, &ignore_path, 5s)) {
+    if (!dm.CreateEmptyDevice(name)) {
         std::cerr << "Failed to create device-mapper device with name: " << name << std::endl;
         return -EIO;
     }
+    if (!dm.LoadTable(name, table_args->table)) {
+        std::cerr << "Failed to load table for dm device: " << name << std::endl;
+        return -EIO;
+    }
+    if (!table_args->suspended && !dm.ChangeState(name, DmDeviceState::ACTIVE)) {
+        std::cerr << "Failed to activate table for " << name << std::endl;
+        return -EIO;
+    }
     return 0;
 }
 
@@ -269,7 +289,6 @@ static int DmDeleteCmdHandler(int argc, char** argv) {
         std::cerr << "Failed to delete [" << name << "]" << std::endl;
         return -EIO;
     }
-
     return 0;
 }
 
@@ -280,17 +299,20 @@ static int DmReplaceCmdHandler(int argc, char** argv) {
     }
     std::string name = argv[0];
 
-    DmTable table;
-    int ret = parse_table_args(&table, argc, argv);
-    if (ret) {
-        return ret;
+    auto table_args = parse_table_args(argc, argv);
+    if (!table_args) {
+        return -EINVAL;
     }
 
     DeviceMapper& dm = DeviceMapper::Instance();
-    if (!dm.LoadTableAndActivate(name, table)) {
+    if (!dm.LoadTable(name, table_args->table)) {
         std::cerr << "Failed to replace device-mapper table to: " << name << std::endl;
         return -EIO;
     }
+    if (!table_args->suspended && !dm.ChangeState(name, DmDeviceState::ACTIVE)) {
+        std::cerr << "Failed to activate table for " << name << std::endl;
+        return -EIO;
+    }
     return 0;
 }
 
diff --git a/init/devices.cpp b/init/devices.cpp
index d4a3cb9d3..ee8738c2a 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -465,7 +465,11 @@ void DeviceHandler::HandleDevice(const std::string& action, const std::string& d
         MakeDevice(devpath, block, major, minor, links);
     }
 
-    // We don't have full device-mapper information until a change event is fired.
+    // Handle device-mapper nodes.
+    // On kernels <= 5.10, the "add" event is fired on DM_DEV_CREATE, but does not contain name
+    // information until DM_TABLE_LOAD - thus, we wait for a "change" event.
+    // On kernels >= 5.15, the "add" event is fired on DM_TABLE_LOAD, followed by a "change"
+    // event.
     if (action == "add" || (action == "change" && StartsWith(devpath, "/dev/block/dm-"))) {
         for (const auto& link : links) {
             if (!mkdir_recursive(Dirname(link), 0755)) {