From 9a3dc8c709b15fe06e4a4babc0f1e32efb0a9955 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 15 Oct 2020 16:54:38 -0700
Subject: [PATCH] IdleMaint: skip swap space, bind mounts, and virtual
 filesystems

When the idle maintenance task runs on Cuttlefish, there are several
warnings printed to logcat after the expected messages:

    D vold    : Starting trim of /data
    I vold    : Trimmed 0 bytes on /data in 36ms
    D vold    : Starting trim of /cache
    I vold    : Trimmed 58662912 bytes on /cache in 0ms
    D vold    : Starting trim of /metadata
    I vold    : Trimmed 7725056 bytes on /metadata in 12ms
    D vold    : Starting trim of none
    W vold    : Failed to open none: No such file or directory
    D vold    : Starting trim of /sdcard
    W vold    : Failed to open /sdcard: Not a directory
    D vold    : Starting trim of /mnt/vendor/shared
    W vold    : Trim failed on /mnt/vendor/shared: Inappropriate ioctl for device

This is because vold gathers the filesystems to trim from the fstab, but
it fails to exclude some entries that aren't appropriate to trim:

    /dev/block/zram0 none swap defaults zramsize=75%
    /tmp /sdcard none defaults,bind recoveryonly
    shared /mnt/vendor/shared virtiofs nosuid,nodev,noatime nofail

These should be excluded because they are swap space, a bind mount, and
a virtual filesystem respectively.

Fix addFromFstab() to exclude the above cases.

Afterwards, the messages on Cuttlefish are:

    D vold    : Starting trim of /data
    I vold    : Trimmed 0 bytes on /data in 39ms
    D vold    : Starting trim of /cache
    I vold    : Trimmed 58662912 bytes on /cache in 0ms
    D vold    : Starting trim of /metadata
    I vold    : Trimmed 9822208 bytes on /metadata in 12ms

Change-Id: Idc575106fe6f81c737f684429d58dba4bd5478ad
---
 IdleMaint.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/IdleMaint.cpp b/IdleMaint.cpp
index 24a1ef9..e4a1806 100644
--- a/IdleMaint.cpp
+++ b/IdleMaint.cpp
@@ -105,12 +105,16 @@ static void addFromVolumeManager(std::list<std::string>* paths, PathTypes path_t
 static void addFromFstab(std::list<std::string>* paths, PathTypes path_type) {
     std::string previous_mount_point;
     for (const auto& entry : fstab_default) {
-        // Skip raw partitions.
-        if (entry.fs_type == "emmc" || entry.fs_type == "mtd") {
+        // Skip raw partitions and swap space.
+        if (entry.fs_type == "emmc" || entry.fs_type == "mtd" || entry.fs_type == "swap") {
             continue;
         }
-        // Skip read-only filesystems
-        if (entry.flags & MS_RDONLY) {
+        // Skip read-only filesystems and bind mounts.
+        if (entry.flags & (MS_RDONLY | MS_BIND)) {
+            continue;
+        }
+        // Skip anything without an underlying block device, e.g. virtiofs.
+        if (entry.blk_device[0] != '/') {
             continue;
         }
         if (entry.fs_mgr_flags.vold_managed) {