Merge "fs_mgr: Skip zram setup on swapon_all if mmd zram management is enabled" into main am: 4dafb93131 am: f70c82794c
Original change: https://android-review.googlesource.com/c/platform/system/core/+/3472228
Change-Id: Iba49ff3351ca598e88a365b7a8d0c88dafdd4414
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index a30d9c0..204e690 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -2023,6 +2023,84 @@
return InstallZramDevice(loop_device);
}
+// Check whether it is in recovery mode or not.
+//
+// This is a copy from util.h in libinit.
+//
+// You need to check ALL relevant executables calling this function has access to
+// "/system/bin/recovery" (including SELinux permissions and UNIX permissions).
+static bool IsRecovery() {
+ return access("/system/bin/recovery", F_OK) == 0;
+}
+
+// Decides whether swapon_all should skip setting up zram.
+//
+// swapon_all is deprecated to setup zram after mmd is launched. swapon_all command should skip
+// setting up zram if mmd is enabled by AConfig flag and mmd is configured to set up zram.
+static bool ShouldSkipZramSetup() {
+ if (IsRecovery()) {
+ // swapon_all continue to support zram setup in recovery mode after mmd launch.
+ return false;
+ }
+
+ // Since AConfig does not support to load the status from init, we use the system property
+ // "mmd.enabled_aconfig" copied from AConfig by `mmd --set-property` command to check whether
+ // mmd is enabled or not.
+ //
+ // aconfig_prop can have either of:
+ //
+ // * "true": mmd is enabled by AConfig
+ // * "false": mmd is disabled by AConfig
+ // * "": swapon_all is executed before `mmd --set-property`
+ //
+ // During mmd being launched, we request OEMs, who decided to use mmd to set up zram, to execute
+ // swapon_all after "mmd.enabled_aconfig" system property is initialized. Init can wait the
+ // "mmd.enabled_aconfig" initialization by `property:mmd.enabled_aconfig=*` trigger.
+ //
+ // After mmd is launched, we deprecate swapon_all command for setting up zram but recommend to
+ // use `mmd --setup-zram`. It means that the system should call swapon_all with fstab with no
+ // zram entry or the system should never call swapon_all.
+ //
+ // As a transition, OEMs can use the deprecated swapon_all to set up zram for several versions
+ // after mmd is launched. swapon_all command will show warning logs during the transition
+ // period.
+ const std::string aconfig_prop = android::base::GetProperty("mmd.enabled_aconfig", "");
+ const bool is_zram_managed_by_mmd = android::base::GetBoolProperty("mmd.zram.enabled", false);
+ if (aconfig_prop == "true" && is_zram_managed_by_mmd) {
+ // Skip zram setup since zram is managed by mmd.
+ //
+ // We expect swapon_all is not called when mmd is enabled by AConfig flag.
+ // TODO: b/394484720 - Make this log as warning after mmd is launched.
+ LINFO << "Skip setting up zram because mmd sets up zram instead.";
+ return true;
+ }
+
+ if (aconfig_prop == "false") {
+ // It is expected to swapon_all command to set up zram before mmd is launched.
+ LOG(DEBUG) << "mmd is not launched yet. swapon_all setup zram.";
+ } else if (is_zram_managed_by_mmd) {
+ // This branch is for aconfig_prop == ""
+
+ // On the system which uses mmd to setup zram, swapon_all must be executed after
+ // mmd.enabled_aconfig is initialized.
+ LERROR << "swapon_all must be called after mmd.enabled_aconfig system "
+ "property is initialized";
+ // Since we don't know whether mmd is enabled on the system or not, we fall back to enable
+ // zram from swapon_all conservatively. Both swapon_all and `mmd --setup-zram` command
+ // trying to set up zram does not break the system but just either ends up failing.
+ } else {
+ // We show the warning log for swapon_all deprecation on both aconfig_prop is "true" and ""
+ // cases.
+ // If mmd is enabled, swapon_all is already deprecated.
+ // If aconfig_prop is "", we don't know whether mmd is launched or not. But we show the
+ // deprecation warning log conservatively.
+ LWARNING << "mmd is recommended to set up zram over swapon_all command with "
+ "fstab entry.";
+ }
+
+ return false;
+}
+
bool fs_mgr_swapon_all(const Fstab& fstab) {
bool ret = true;
for (const auto& entry : fstab) {
@@ -2032,6 +2110,10 @@
}
if (entry.zram_size > 0) {
+ if (ShouldSkipZramSetup()) {
+ continue;
+ }
+
if (!PrepareZramBackingDevice(entry.zram_backingdev_size)) {
LERROR << "Failure of zram backing device file for '" << entry.blk_device << "'";
}
diff --git a/init/README.md b/init/README.md
index 89e20a4..c9742ad 100644
--- a/init/README.md
+++ b/init/README.md
@@ -785,6 +785,16 @@
fstab.${ro.hardware} or fstab.${ro.hardware.platform} will be scanned for
under /odm/etc, /vendor/etc, or / at runtime, in that order.
+> swapon_all is deprecated and will do nothing if `mmd_enabled` AConfig flag
+ in `system_performance` namespace and `mmd.zram.enabled` sysprop are enabled.
+ OEMs, who decided to use mmd to manage zram, must remove zram entry from fstab
+ or remove swapon_all call from their init script.
+
+> swapon_all continues to support setting up non-zram swap devices.
+
+> swapon_all on recovery mode continues to support setting up zram because mmd
+ does not support the recovery mode.
+
`swapoff <path>`
> Stops swapping to the file or block device specified by path.