diff --git a/db/column_family.cc b/db/column_family.cc
index e749cb9ee..a2885515c 100644
--- a/db/column_family.cc
+++ b/db/column_family.cc
@@ -75,11 +75,6 @@ ColumnFamilyHandleImpl::~ColumnFamilyHandleImpl() {
       bool defer_purge =
           db_->immutable_db_options().avoid_unnecessary_blocking_io;
       db_->PurgeObsoleteFiles(job_context, defer_purge);
-      if (defer_purge) {
-        mutex_->Lock();
-        db_->SchedulePurge();
-        mutex_->Unlock();
-      }
     }
     job_context.Clean();
   }
diff --git a/db/db_filesnapshot.cc b/db/db_filesnapshot.cc
index c9694c751..35d75c823 100644
--- a/db/db_filesnapshot.cc
+++ b/db/db_filesnapshot.cc
@@ -127,31 +127,30 @@ Status DBImpl::GetLiveFiles(std::vector<std::string>& ret,
 }
 
 Status DBImpl::GetSortedWalFiles(VectorLogPtr& files) {
+  // If caller disabled deletions, this function should return files that are
+  // guaranteed not to be deleted until deletions are re-enabled. We need to
+  // wait for pending purges to finish since WalManager doesn't know which
+  // files are going to be purged. Additional purges won't be scheduled as
+  // long as deletions are disabled (so the below loop must terminate).
+  // Also note that we disable deletions anyway to avoid the case where a
+  // file is deleted in the middle of the scan, causing IO error.
+  Status deletions_disabled = DisableFileDeletions();
   {
-    // If caller disabled deletions, this function should return files that are
-    // guaranteed not to be deleted until deletions are re-enabled. We need to
-    // wait for pending purges to finish since WalManager doesn't know which
-    // files are going to be purged. Additional purges won't be scheduled as
-    // long as deletions are disabled (so the below loop must terminate).
     InstrumentedMutexLock l(&mutex_);
-    while (disable_delete_obsolete_files_ > 0 &&
-           (pending_purge_obsolete_files_ > 0 || bg_purge_scheduled_ > 0)) {
+    while (pending_purge_obsolete_files_ > 0 || bg_purge_scheduled_ > 0) {
       bg_cv_.Wait();
     }
   }
 
-  // Disable deletion in order to avoid the case where a file is deleted in
-  // the middle of the process so IO error is returned.
-  Status s = DisableFileDeletions();
-  bool file_deletion_supported = !s.IsNotSupported();
-  if (s.ok() || !file_deletion_supported) {
-    s = wal_manager_.GetSortedWalFiles(files);
-    if (file_deletion_supported) {
-      Status s2 = EnableFileDeletions(false);
-      if (!s2.ok() && s.ok()) {
-        s = s2;
-      }
-    }
+  Status s = wal_manager_.GetSortedWalFiles(files);
+
+  // DisableFileDeletions / EnableFileDeletions not supported in read-only DB
+  if (deletions_disabled.ok()) {
+    Status s2 = EnableFileDeletions(/*force*/ false);
+    assert(s2.ok());
+    s2.PermitUncheckedError();
+  } else {
+    assert(deletions_disabled.IsNotSupported());
   }
 
   return s;
diff --git a/db/db_impl/db_impl.cc b/db/db_impl/db_impl.cc
index 190ad54b2..1ff9880b8 100644
--- a/db/db_impl/db_impl.cc
+++ b/db/db_impl/db_impl.cc
@@ -1546,6 +1546,8 @@ void DBImpl::BackgroundCallPurge() {
     mutex_.Lock();
   }
 
+  assert(bg_purge_scheduled_ > 0);
+
   // Can't use iterator to go over purge_files_ because inside the loop we're
   // unlocking the mutex that protects purge_files_.
   while (!purge_files_.empty()) {
@@ -1613,17 +1615,7 @@ static void CleanupIteratorState(void* arg1, void* /*arg2*/) {
       delete state->super_version;
     }
     if (job_context.HaveSomethingToDelete()) {
-      if (state->background_purge) {
-        // PurgeObsoleteFiles here does not delete files. Instead, it adds the
-        // files to be deleted to a job queue, and deletes it in a separate
-        // background thread.
-        state->db->PurgeObsoleteFiles(job_context, true /* schedule only */);
-        state->mu->Lock();
-        state->db->SchedulePurge();
-        state->mu->Unlock();
-      } else {
-        state->db->PurgeObsoleteFiles(job_context);
-      }
+      state->db->PurgeObsoleteFiles(job_context, state->background_purge);
     }
     job_context.Clean();
   }
diff --git a/db/db_impl/db_impl_files.cc b/db/db_impl/db_impl_files.cc
index 6007d2ffb..7ce1a0ae4 100644
--- a/db/db_impl/db_impl_files.cc
+++ b/db/db_impl/db_impl_files.cc
@@ -56,6 +56,8 @@ Status DBImpl::DisableFileDeletions() {
   return s;
 }
 
+// FIXME: can be inconsistent with DisableFileDeletions in cases like
+// DBImplReadOnly
 Status DBImpl::DisableFileDeletionsWithLock() {
   mutex_.AssertHeld();
   ++disable_delete_obsolete_files_;
@@ -642,6 +644,11 @@ void DBImpl::PurgeObsoleteFiles(JobContext& state, bool schedule_only) {
   InstrumentedMutexLock l(&mutex_);
   --pending_purge_obsolete_files_;
   assert(pending_purge_obsolete_files_ >= 0);
+  if (schedule_only) {
+    // Must change from pending_purge_obsolete_files_ to bg_purge_scheduled_
+    // while holding mutex (for GetSortedWalFiles() etc.)
+    SchedulePurge();
+  }
   if (pending_purge_obsolete_files_ == 0) {
     bg_cv_.SignalAll();
   }
@@ -657,11 +664,6 @@ void DBImpl::DeleteObsoleteFiles() {
   if (job_context.HaveSomethingToDelete()) {
     bool defer_purge = immutable_db_options_.avoid_unnecessary_blocking_io;
     PurgeObsoleteFiles(job_context, defer_purge);
-    if (defer_purge) {
-      mutex_.Lock();
-      SchedulePurge();
-      mutex_.Unlock();
-    }
   }
   job_context.Clean();
   mutex_.Lock();