backport rocksdb diskspace bugfix (#14354)

jsteemann · KVS85 · web-flow · commit 2181a66df20c · 2021-06-19T10:58:06.000+03:00
* backport rocksdb diskspace bugfix

* Backport bugfix from upstream rocksdb repository for calculating the
  free disk space for the database directory. Before the bugfix, rocksdb
  could overestimate the amount of free space when the arangod process
  was run as non-privileged users.

* Update CHANGELOG

Co-authored-by: Vadim &lt;vadim@arangodb.com&gt;
diff --git a/3rdParty/rocksdb/6.8/env/fs_posix.cc b/3rdParty/rocksdb/6.8/env/fs_posix.cc
@@ -832,7 +832,17 @@ class PosixFileSystem : public FileSystem {
       return IOError("While doing statvfs", fname, errno);
     }
 
-    *free_space = ((uint64_t)sbuf.f_bsize * sbuf.f_bfree);
+    // sbuf.bfree is total free space available to root
+    // sbuf.bavail is total free space available to unprivileged user
+    //  sbuf.bavail <= sbuf.bfree ... pick correct based upon effective user id
+    if (geteuid()) {
+      // non-zero user is unprivileged, or -1 if error.  take more conservative
+      // size
+      *free_space = ((uint64_t)sbuf.f_bsize * sbuf.f_bavail);
+    } else {
+      // root user can access all disk space
+      *free_space = ((uint64_t)sbuf.f_bsize * sbuf.f_bfree);
+    }
     return IOStatus::OK();
   }
 
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,6 +1,11 @@
 v3.7.13 (XXXX-XX-XX)
 --------------------
 
+* Backport bugfix from upstream rocksdb repository for calculating the free disk
+  space for the database directory. Before the bugfix, rocksdb could
+  overestimate the amount of free space when the arangod process was run as
+  non-privileged users.
+
 * Fixed a problem with active failover, where a failover could take 5 mins
   because the follower was caught in a bad state during replication. This fixes
   BTS-425.
