add existing path, least free space policy. closes #216

src/policy_eplfs.cpp

@@ -0,0 +1,108 @@
+/*
+  Copyright (c) 2016, Antonio SJ Musumeci <trapexit@spawn.link>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <sys/statvfs.h>
+
+#include <string>
+#include <vector>
+
+#include "fs_path.hpp"
+#include "policy.hpp"
+
+using std::string;
+using std::vector;
+using std::size_t;
+using mergerfs::Policy;
+using mergerfs::Category;
+typedef struct statvfs statvfs_t;
+
+static
+void
+_calc_lfs(const statvfs_t  &fsstats,
+          const string     *basepath,
+          const size_t      minfreespace,
+          fsblkcnt_t       &lfs,
+          const string    *&lfsbasepath)
+{
+  fsblkcnt_t spaceavail;
+
+  spaceavail = (fsstats.f_frsize * fsstats.f_bavail);
+  if((spaceavail > minfreespace) && (spaceavail < lfs))
+    {
+      lfs         = spaceavail;
+      lfsbasepath = basepath;
+    }
+}
+
+static
+int
+_eplfs(const Category::Enum::Type  type,
+       const vector<string>       &basepaths,
+       const char                 *fusepath,
+       const size_t                minfreespace,
+       vector<const string*>      &paths)
+{
+  int rv;
+  string fullpath;
+  statvfs_t fsstats;
+  fsblkcnt_t eplfs;
+  const string *eplfsbasepath;
+
+  eplfs = -1;
+  eplfsbasepath = NULL;
+  for(size_t i = 0, ei = basepaths.size(); i != ei; i++)
+    {
+      const string *basepath = &basepaths[i];
+
+      fs::path::make(basepath,fusepath,fullpath);
+
+      rv = ::statvfs(fullpath.c_str(),&fsstats);
+      if(rv == 0)
+        _calc_lfs(fsstats,basepath,minfreespace,eplfs,eplfsbasepath);
+    }
+
+  if(eplfsbasepath == NULL)
+    return -ENOENT;
+
+  paths.push_back(eplfsbasepath);
+
+  return 0;
+}
+
+namespace mergerfs
+{
+  int
+  Policy::Func::eplfs(const Category::Enum::Type  type,
+                      const vector<string>       &basepaths,
+                      const char                 *fusepath,
+                      const size_t                minfreespace,
+                      vector<const string*>     &paths)
+  {
+    int rv;
+    const size_t minfs =
+      ((type == Category::Enum::create) ? minfreespace : 0);
+
+    rv = _eplfs(type,basepaths,fusepath,minfs,paths);
+    if(rv != 0)
+      rv = Policy::Func::lfs(type,basepaths,fusepath,minfreespace,paths);
+
+    return rv;
+  }
+}