Adds /dev/block/by-name/<partition> symlinks
During uevent processing, some "by-name" symlinks will be created.
/dev/block/<type>/<device>/by-name/<partition>
<type> can be: platform, pci or vbd.
<device> might be: soc.0/f9824900.sdhci, soc.0/f9824900.sdhci, etc.
<partition> might be: system, vendor, system_a, system_b, etc.
e.g., on a non-A/B device:
/dev/block/platform/soc.0/f9824900.sdhci/by-name/system
/dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor
On a A/B device:
/dev/block/platform/soc/1da4000.ufshc/by-name/system_a
/dev/block/platform/soc/1da4000.ufshc/by-name/system_b
/dev/block/platform/soc/1da4000.ufshc/by-name/vendor_a
/dev/block/platform/soc/1da4000.ufshc/by-name/vendor_b
However, those symlinks are "device-specific".
This change adds the "generic" symlinks in ueventd, in addition to
the existing symlinks, when the possible "boot devices" are specified
in device tree. e.g.,
&firmware_android {
compatible = "android,firmware";
boot_devices ="soc/1da4000.ufshc,soc.0/f9824900.sdhci";
}
The following symlinks will then be created on the aforementioned non-A/B
and A/B devices, respectively.
/dev/block/by-name/system
/dev/block/by-name/vendor
/dev/block/by-name/system_a
/dev/block/by-name/system_b
/dev/block/by-name/vendor_a
/dev/block/by-name/vendor_b
Note that both <type> and <device> are skipped in the newly create symlinks.
It assumes there is no more than one devices with the same <partition>,
which is the assumption of current first stage mount flow.
Finally, when 'boot_devices' in DT is absent, it fallbacks to extract
'boot_devices' from fstab settings. e.g., using 'soc/1da4000.ufshc',
'soc.0/f9824900.sdhci' for a fstab with the following content:
/dev/block/platform/soc/1da4000.ufshc/by-name/system
/dev/block/platform/soc.0/f9824900.sdhci/by-name/vendor
Bug: 78613232
Test: adb shell ls /dev/block/by-name
Change-Id: Iec920b5a72409b6a2bdbeeb290f0a3acd2046b5d
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index 472ab59..af4d6c1 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -686,6 +686,49 @@
return a;
}
+/* Extracts <device>s from the by-name symlinks specified in a fstab:
+ * /dev/block/<type>/<device>/by-name/<partition>
+ *
+ * <type> can be: platform, pci or vbd.
+ *
+ * For example, given the following entries in the input fstab:
+ * /dev/block/platform/soc/1da4000.ufshc/by-name/system
+ * /dev/block/pci/soc.0/f9824900.sdhci/by-name/vendor
+ * it returns a set { "soc/1da4000.ufshc", "soc.0/f9824900.sdhci" }.
+ */
+static std::set<std::string> extract_boot_devices(const fstab& fstab) {
+ std::set<std::string> boot_devices;
+
+ for (int i = 0; i < fstab.num_entries; i++) {
+ std::string blk_device(fstab.recs[i].blk_device);
+ // Skips blk_device that doesn't conform to the format.
+ if (!android::base::StartsWith(blk_device, "/dev/block") ||
+ android::base::StartsWith(blk_device, "/dev/block/by-name") ||
+ android::base::StartsWith(blk_device, "/dev/block/bootdevice/by-name")) {
+ continue;
+ }
+ // Skips non-by_name blk_device.
+ // /dev/block/<type>/<device>/by-name/<partition>
+ // ^ slash_by_name
+ auto slash_by_name = blk_device.find("/by-name");
+ if (slash_by_name == std::string::npos) continue;
+ blk_device.erase(slash_by_name); // erases /by-name/<partition>
+
+ // Erases /dev/block/, now we have <type>/<device>
+ blk_device.erase(0, std::string("/dev/block/").size());
+
+ // <type>/<device>
+ // ^ first_slash
+ auto first_slash = blk_device.find('/');
+ if (first_slash == std::string::npos) continue;
+
+ auto boot_device = blk_device.substr(first_slash + 1);
+ if (!boot_device.empty()) boot_devices.insert(std::move(boot_device));
+ }
+
+ return boot_devices;
+}
+
struct fstab *fs_mgr_read_fstab(const char *fstab_path)
{
FILE *fstab_file;
@@ -863,6 +906,23 @@
return nullptr;
}
+std::set<std::string> fs_mgr_get_boot_devices() {
+ // boot_devices can be specified in device tree.
+ std::string dt_value;
+ std::string file_name = get_android_dt_dir() + "/boot_devices";
+ if (read_dt_file(file_name, &dt_value)) {
+ auto boot_devices = android::base::Split(dt_value, ",");
+ return std::set<std::string>(boot_devices.begin(), boot_devices.end());
+ }
+
+ // Fallback to extract boot devices from fstab.
+ std::unique_ptr<fstab, decltype(&fs_mgr_free_fstab)> fstab(fs_mgr_read_fstab_default(),
+ fs_mgr_free_fstab);
+ if (fstab) return extract_boot_devices(*fstab);
+
+ return {};
+}
+
int fs_mgr_is_voldmanaged(const struct fstab_rec *fstab)
{
return fstab->fs_mgr_flags & MF_VOLDMANAGED;
diff --git a/fs_mgr/include_fstab/fstab/fstab.h b/fs_mgr/include_fstab/fstab/fstab.h
index 04ccfc5..d232cca 100644
--- a/fs_mgr/include_fstab/fstab/fstab.h
+++ b/fs_mgr/include_fstab/fstab/fstab.h
@@ -22,6 +22,7 @@
#include <stdint.h>
#include <stdio.h>
+#include <set>
#include <string>
/*
@@ -89,5 +90,6 @@
int fs_mgr_has_sysfs_path(const struct fstab_rec* fstab);
std::string fs_mgr_get_slot_suffix();
+std::set<std::string> fs_mgr_get_boot_devices();
#endif /* __CORE_FS_TAB_H */
diff --git a/init/devices.cpp b/init/devices.cpp
index 688ad61..ada1e28 100644
--- a/init/devices.cpp
+++ b/init/devices.cpp
@@ -329,6 +329,10 @@
<< partition_name_sanitized << "'";
}
links.emplace_back(link_path + "/by-name/" + partition_name_sanitized);
+ // Adds symlink: /dev/block/by-name/<partition_name>.
+ if (boot_devices_.find(device) != boot_devices_.end()) {
+ links.emplace_back("/dev/block/by-name/" + partition_name_sanitized);
+ }
}
auto last_slash = uevent.path.rfind('/');
@@ -346,8 +350,14 @@
PLOG(ERROR) << "Failed to create directory " << Dirname(link);
}
- if (symlink(devpath.c_str(), link.c_str()) && errno != EEXIST) {
- PLOG(ERROR) << "Failed to symlink " << devpath << " to " << link;
+ if (symlink(devpath.c_str(), link.c_str())) {
+ if (errno != EEXIST) {
+ PLOG(ERROR) << "Failed to symlink " << devpath << " to " << link;
+ } else if (std::string link_path;
+ Readlink(link, &link_path) && link_path != devpath) {
+ PLOG(ERROR) << "Failed to symlink " << devpath << " to " << link
+ << ", which already links to: " << link_path;
+ }
}
}
}
@@ -411,16 +421,18 @@
DeviceHandler::DeviceHandler(std::vector<Permissions> dev_permissions,
std::vector<SysfsPermissions> sysfs_permissions,
- std::vector<Subsystem> subsystems, bool skip_restorecon)
+ std::vector<Subsystem> subsystems, std::set<std::string> boot_devices,
+ bool skip_restorecon)
: dev_permissions_(std::move(dev_permissions)),
sysfs_permissions_(std::move(sysfs_permissions)),
subsystems_(std::move(subsystems)),
+ boot_devices_(std::move(boot_devices)),
skip_restorecon_(skip_restorecon),
sysfs_mount_point_("/sys") {}
DeviceHandler::DeviceHandler()
: DeviceHandler(std::vector<Permissions>{}, std::vector<SysfsPermissions>{},
- std::vector<Subsystem>{}, false) {}
+ std::vector<Subsystem>{}, std::set<std::string>{}, false) {}
} // namespace init
} // namespace android
diff --git a/init/devices.h b/init/devices.h
index 1f8f1e8..f9035da 100644
--- a/init/devices.h
+++ b/init/devices.h
@@ -21,6 +21,7 @@
#include <sys/types.h>
#include <algorithm>
+#include <set>
#include <string>
#include <vector>
@@ -103,8 +104,8 @@
DeviceHandler();
DeviceHandler(std::vector<Permissions> dev_permissions,
- std::vector<SysfsPermissions> sysfs_permissions,
- std::vector<Subsystem> subsystems, bool skip_restorecon);
+ std::vector<SysfsPermissions> sysfs_permissions, std::vector<Subsystem> subsystems,
+ std::set<std::string> boot_devices, bool skip_restorecon);
~DeviceHandler(){};
void HandleDeviceEvent(const Uevent& uevent);
@@ -125,6 +126,7 @@
std::vector<Permissions> dev_permissions_;
std::vector<SysfsPermissions> sysfs_permissions_;
std::vector<Subsystem> subsystems_;
+ std::set<std::string> boot_devices_;
bool skip_restorecon_;
std::string sysfs_mount_point_;
};
diff --git a/init/init_first_stage.cpp b/init/init_first_stage.cpp
index 28df696..34de640 100644
--- a/init/init_first_stage.cpp
+++ b/init/init_first_stage.cpp
@@ -77,7 +77,7 @@
std::unique_ptr<LogicalPartitionTable> dm_linear_table_;
std::vector<fstab_rec*> mount_fstab_recs_;
std::set<std::string> required_devices_partition_names_;
- DeviceHandler device_handler_;
+ std::unique_ptr<DeviceHandler> device_handler_;
UeventListener uevent_listener_;
};
@@ -147,6 +147,11 @@
if (IsDmLinearEnabled()) {
dm_linear_table_ = android::fs_mgr::LoadPartitionsFromDeviceTree();
}
+
+ auto boot_devices = fs_mgr_get_boot_devices();
+ device_handler_ =
+ std::make_unique<DeviceHandler>(std::vector<Permissions>{}, std::vector<SysfsPermissions>{},
+ std::vector<Subsystem>{}, std::move(boot_devices), false);
}
std::unique_ptr<FirstStageMount> FirstStageMount::Create() {
@@ -205,7 +210,7 @@
bool found = false;
auto dm_callback = [this, &dm_path, &found](const Uevent& uevent) {
if (uevent.path == dm_path) {
- device_handler_.HandleDeviceEvent(uevent);
+ device_handler_->HandleDeviceEvent(uevent);
found = true;
return ListenerAction::kStop;
}
@@ -262,7 +267,7 @@
if (iter != required_devices_partition_names_.end()) {
LOG(VERBOSE) << __PRETTY_FUNCTION__ << ": found partition: " << *iter;
required_devices_partition_names_.erase(iter);
- device_handler_.HandleDeviceEvent(uevent);
+ device_handler_->HandleDeviceEvent(uevent);
if (required_devices_partition_names_.empty()) {
return ListenerAction::kStop;
} else {
@@ -299,7 +304,7 @@
auto verity_callback = [&device_name, &dm_device, this, &found](const Uevent& uevent) {
if (uevent.device_name == device_name) {
LOG(VERBOSE) << "Creating device-mapper device : " << dm_device;
- device_handler_.HandleDeviceEvent(uevent);
+ device_handler_->HandleDeviceEvent(uevent);
found = true;
return ListenerAction::kStop;
}
@@ -469,7 +474,7 @@
// is not empty. e.g.,
// - /dev/block/platform/soc.0/f9824900.sdhci/by-name/modem
// - /dev/block/platform/soc.0/f9824900.sdhci/mmcblk0p1
- std::vector<std::string> links = device_handler_.GetBlockDeviceSymlinks(uevent);
+ std::vector<std::string> links = device_handler_->GetBlockDeviceSymlinks(uevent);
if (!links.empty()) {
auto[it, inserted] = by_name_symlink_map_.emplace(uevent.partition_name, links[0]);
if (!inserted) {
diff --git a/init/ueventd.cpp b/init/ueventd.cpp
index 1435d82..a284203 100644
--- a/init/ueventd.cpp
+++ b/init/ueventd.cpp
@@ -30,6 +30,7 @@
#include <android-base/chrono_utils.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
+#include <fstab/fstab.h>
#include <selinux/android.h>
#include <selinux/selinux.h>
@@ -242,8 +243,9 @@
std::string hardware = android::base::GetProperty("ro.hardware", "");
parser.ParseConfig("/ueventd." + hardware + ".rc");
+ auto boot_devices = fs_mgr_get_boot_devices();
return DeviceHandler(std::move(dev_permissions), std::move(sysfs_permissions),
- std::move(subsystems), true);
+ std::move(subsystems), std::move(boot_devices), true);
}
int ueventd_main(int argc, char** argv) {
