From 1f3e92c34ed26110ef2f742a855b89781b8c095b Mon Sep 17 00:00:00 2001
From: Jerry Wong <jerry.wong@broadcom.com>
Date: Fri, 9 Jul 2021 09:53:21 -0700
Subject: [PATCH] Enhance checkpoint=disable GC threshold fallback mechanism

Enhanced the checkpoint=disable GC threshold fallback mechanism by first
dropping to checkpoint=disable before dropping the option completely for
kernel compatibility.

Test: atest vts_kernel_checkpoint_test
Bug: 193216993
Change-Id: I50ecdf3a82eb7bc677965e8fd3821227fd41bfc2
Signed-off-by: Jerry Wong <jerry.wong@broadcom.com>
---
 fs_mgr/fs_mgr.cpp | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/fs_mgr/fs_mgr.cpp b/fs_mgr/fs_mgr.cpp
index 01c8ad3c4..4826ccf6c 100644
--- a/fs_mgr/fs_mgr.cpp
+++ b/fs_mgr/fs_mgr.cpp
@@ -790,20 +790,26 @@ static int __mount(const std::string& source, const std::string& target, const F
     int save_errno = 0;
     int gc_allowance = 0;
     std::string opts;
+    std::string checkpoint_opts;
     bool try_f2fs_gc_allowance = is_f2fs(entry.fs_type) && entry.fs_checkpoint_opts.length() > 0;
+    bool try_f2fs_fallback = false;
     Timer t;
 
     do {
-        if (save_errno == EINVAL && try_f2fs_gc_allowance) {
-            PINFO << "Kernel does not support checkpoint=disable:[n]%, trying without.";
+        if (save_errno == EINVAL && (try_f2fs_gc_allowance || try_f2fs_fallback)) {
+            PINFO << "Kernel does not support " << checkpoint_opts << ", trying without.";
             try_f2fs_gc_allowance = false;
+            // Attempt without gc allowance before dropping.
+            try_f2fs_fallback = !try_f2fs_fallback;
         }
         if (try_f2fs_gc_allowance) {
-            opts = entry.fs_options + entry.fs_checkpoint_opts + ":" +
-                   std::to_string(gc_allowance) + "%";
+            checkpoint_opts = entry.fs_checkpoint_opts + ":" + std::to_string(gc_allowance) + "%";
+        } else if (try_f2fs_fallback) {
+            checkpoint_opts = entry.fs_checkpoint_opts;
         } else {
-            opts = entry.fs_options;
+            checkpoint_opts = "";
         }
+        opts = entry.fs_options + checkpoint_opts;
         if (save_errno == EAGAIN) {
             PINFO << "Retrying mount (source=" << source << ",target=" << target
                   << ",type=" << entry.fs_type << ", gc_allowance=" << gc_allowance << "%)=" << ret
@@ -814,7 +820,7 @@ static int __mount(const std::string& source, const std::string& target, const F
         save_errno = errno;
         if (try_f2fs_gc_allowance) gc_allowance += 10;
     } while ((ret && save_errno == EAGAIN && gc_allowance <= 100) ||
-             (ret && save_errno == EINVAL && try_f2fs_gc_allowance));
+             (ret && save_errno == EINVAL && (try_f2fs_gc_allowance || try_f2fs_fallback)));
     const char* target_missing = "";
     const char* source_missing = "";
     if (save_errno == ENOENT) {