stat: Add param to identify storage reservation type

We have three knobs to control storage reservation:
1. The knob/param to set storage reservation for apps. The same value
   for both the skopeo and docker storage even if they are located on
   different volumes.
2. The knob to set `min-free-space-percent` parameter of the sysroot's
   ostree repo. This value is used by libostree during committing/adding
   an object to a repo. The check occurs per each object, just before
   adding it.
3. The knob to set the reserved space value that is used before pulling
   an ostree commit if static delta statistic is available.

Therefore, we need a way to identify these three types of knobs. For
example, it's useful to see in the storage usage statistic which of the
knobs is applied in a given case.

Signed-off-by: Mike Sul <[email protected]>

src/rootfstreemanager.cc

@@ -35,7 +35,8 @@ std::tuple<bool, std::string> RootfsTreeManager::prePullCheck(const DeltaStat& d
   bool ok{true};
 
   try {
-    storage::Volume::getUsageInfo(sysroot_->repoPath(), sysroot_->reservedStorageSpacePercentageDelta(), usage_info);
+    storage::Volume::getUsageInfo(sysroot_->repoPath(), sysroot_->reservedStorageSpacePercentageDelta(),
+                                  OSTree::Sysroot::Config::ReservedStorageSpacePercentageDeltaParamName, usage_info);
     ok = usage_info.available.first >= delta_stat.uncompressedSize;
     msg << "required: " << usage_info.toRelativeType(delta_stat.uncompressedSize) << ", " << usage_info;
   } catch (const std::exception& exc) {

src/storage/stat.cc

@@ -34,7 +34,8 @@ static void getStat(const std::string& path, Stat& stat) {
   stat.blockSize = fs_stat.f_bsize;  // f_frsize == f_bsize on the linux-based systems
 }
 
-void Volume::getUsageInfo(const std::string& path, unsigned int reserved_percentage, UsageInfo& usage_info) {
+void Volume::getUsageInfo(const std::string& path, unsigned int reserved_percentage, const std::string& reserved_by,
+                          UsageInfo& usage_info) {
   Stat stat{};
   getStat(path, stat);
 
@@ -50,6 +51,7 @@ void Volume::getUsageInfo(const std::string& path, unsigned int reserved_percent
       (usage_info.free.first > usage_info.reserved.first) ? (usage_info.free.first - usage_info.reserved.first) : 0,
       (usage_info.free.second > usage_info.reserved.second) ? (usage_info.free.second - usage_info.reserved.second)
                                                             : 0};
+  usage_info.reserved_by = reserved_by;
 }
 
 Volume::UsageInfo::Type Volume::UsageInfo::toRelativeType(const uint64_t& val) const {
@@ -68,8 +70,8 @@ ostream& operator<<(ostream& os, const storage::Volume::UsageInfo::Type& t) {
 }
 
 ostream& operator<<(ostream& os, const storage::Volume::UsageInfo& t) {
-  os << "path " << t.path << ", size: " << t.size << ", free: " << t.free << ", reserved: " << t.reserved
-     << ", available: " << t.available;
+  os << "path " << t.path << ", size: " << t.size << ", free: " << t.free << ", reserved: " << t.reserved << "(by `"
+     << t.reserved_by << "`), available: " << t.available;
   return os;
 }
 

src/storage/stat.h

@@ -16,11 +16,13 @@ struct Volume {
     Type free;
     Type reserved;
     Type available;
+    std::string reserved_by;
 
     Type toRelativeType(const uint64_t& val) const;
   };
 
-  static void getUsageInfo(const std::string& path, unsigned int reserved_percentage, UsageInfo& usage_info);
+  static void getUsageInfo(const std::string& path, unsigned int reserved_percentage, const std::string& reserved_by,
+                           UsageInfo& usage_info);
 };
 
 }  // namespace storage

tests/nospace_test.cc

@@ -83,6 +83,7 @@ TEST(StorageStat, UsageInfo) {
     uint64_t block_numb{100};
     unsigned int free_percentage{15};
     unsigned int reserved_percentage{10};
+    const auto reserved_by{"ostree_min_free_space"};
 
     storage::Volume::UsageInfo::Type free{std::ceil(block_numb * (free_percentage / 100.0)) * block_size,
                                           free_percentage};
@@ -94,11 +95,12 @@ TEST(StorageStat, UsageInfo) {
     SetBlockSize(block_size);
     SetFreeBlockNumb(std::ceil(block_numb * (free_percentage / 100.0)), block_numb);
     storage::Volume::UsageInfo usage_info;
-    storage::Volume::getUsageInfo("./", reserved_percentage, usage_info);
+    storage::Volume::getUsageInfo("./", reserved_percentage, reserved_by, usage_info);
     ASSERT_EQ(free, usage_info.free) << usage_info.free.first;
     ASSERT_EQ(reserved, usage_info.reserved) << usage_info.free.first;
     ASSERT_EQ((free.first - reserved.first), usage_info.available.first) << usage_info.available.first;
     ASSERT_EQ((free.second - reserved.second), usage_info.available.second) << usage_info.available.second;
+    ASSERT_EQ(reserved_by, usage_info.reserved_by) << usage_info.reserved_by;
   }
   {
     // The same amount of free and reserved space
@@ -117,7 +119,7 @@ TEST(StorageStat, UsageInfo) {
     SetBlockSize(block_size);
     SetFreeBlockNumb(std::ceil(block_numb * (free_percentage / 100.0)), block_numb);
     storage::Volume::UsageInfo usage_info;
-    storage::Volume::getUsageInfo("./", reserved_percentage, usage_info);
+    storage::Volume::getUsageInfo("./", reserved_percentage, "", usage_info);
     ASSERT_EQ(free, usage_info.free) << usage_info.free.first;
     ASSERT_EQ(reserved, usage_info.reserved) << usage_info.reserved.first;
     ASSERT_EQ((free.first - reserved.first), usage_info.available.first) << usage_info.available.first;
@@ -141,7 +143,7 @@ TEST(StorageStat, UsageInfo) {
     SetBlockSize(block_size);
     SetFreeBlockNumb(std::ceil(block_numb * (free_percentage / 100.0)), block_numb);
     storage::Volume::UsageInfo usage_info;
-    storage::Volume::getUsageInfo("./", reserved_percentage, usage_info);
+    storage::Volume::getUsageInfo("./", reserved_percentage, "", usage_info);
     ASSERT_EQ(free, usage_info.free) << usage_info.free.first;
     ASSERT_EQ(reserved, usage_info.reserved) << usage_info.reserved.first;
     ASSERT_EQ(storage::Volume::UsageInfo::Type(0, 0), usage_info.available) << usage_info.available.first;