diff --git a/HISTORY.md b/HISTORY.md
index 604b09673..1cd302d7e 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -3,6 +3,8 @@
 ### Behavior Changes
 * Added API comments clarifying safe usage of Disable/EnableManualCompaction and EventListener callbacks for compaction.
 * Obsolete keys in the bottommost level that were preserved for a snapshot will now be cleaned upon snapshot release in all cases. This form of compaction (snapshot release triggered compaction) previously had an artificial limitation that multiple tombstones needed to be present.
+### Bug Fixes
+* fs_posix.cc GetFreeSpace() always report disk space available to root even when running as non-root.  Linux defaults often have disk mounts with 5 to 10 percent of total space reserved only for root.  Out of space could result for non-root users.
 
 ## 6.21.0 (2021-05-21)
 ### Bug Fixes
diff --git a/env/fs_posix.cc b/env/fs_posix.cc
index 84bab192b..a3e360806 100644
--- a/env/fs_posix.cc
+++ b/env/fs_posix.cc
@@ -15,7 +15,6 @@
 #endif
 #include <errno.h>
 #include <fcntl.h>
-
 #include <pthread.h>
 #include <signal.h>
 #include <stdio.h>
@@ -32,6 +31,7 @@
 #include <sys/time.h>
 #include <sys/types.h>
 #include <time.h>
+
 #include <algorithm>
 // Get nano time includes
 #if defined(OS_LINUX) || defined(OS_FREEBSD)
@@ -81,9 +81,7 @@ inline mode_t GetDBFileMode(bool allow_non_owner_access) {
   return allow_non_owner_access ? 0644 : 0600;
 }
 
-static uint64_t gettid() {
-  return Env::Default()->GetThreadID();
-}
+static uint64_t gettid() { return Env::Default()->GetThreadID(); }
 
 // list of pathnames that are locked
 // Only used for error message.
@@ -267,8 +265,7 @@ class PosixFileSystem : public FileSystem {
   }
 
   virtual IOStatus OpenWritableFile(const std::string& fname,
-                                    const FileOptions& options,
-                                    bool reopen,
+                                    const FileOptions& options, bool reopen,
                                     std::unique_ptr<FSWritableFile>* result,
                                     IODebugContext* /*dbg*/) {
     result->reset();
@@ -551,8 +548,8 @@ class PosixFileSystem : public FileSystem {
   }
 
   IOStatus NewLogger(const std::string& fname, const IOOptions& /*opts*/,
-                   std::shared_ptr<Logger>* result,
-                   IODebugContext* /*dbg*/) override {
+                     std::shared_ptr<Logger>* result,
+                     IODebugContext* /*dbg*/) override {
     FILE* f = nullptr;
     int fd;
     {
@@ -909,7 +906,17 @@ 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();
   }
 
@@ -938,7 +945,7 @@ class PosixFileSystem : public FileSystem {
   }
 
   FileOptions OptimizeForLogWrite(const FileOptions& file_options,
-                                 const DBOptions& db_options) const override {
+                                  const DBOptions& db_options) const override {
     FileOptions optimized = file_options;
     optimized.use_mmap_writes = false;
     optimized.use_direct_writes = false;