os/bluestore: fix off-by-one on caching tail block

We can cache the tail as long as we overwrite all prior content;
we don't have to extent the size.

Signed-off-by: Sage Weil <sage@redhat.com>

diff --git a/src/os/bluestore/BlueStore.cc b/src/os/bluestore/BlueStore.cc
index ef63b9488e3ca8420c3c7d1aec54edadd040a925..ca1f93d352016926b65cb509ca3b3584cb1bcd26 100644 (file)
--- a/src/os/bluestore/BlueStore.cc
+++ b/src/os/bluestore/BlueStore.cc
@@ -4921,7 +4921,7 @@ void BlueStore::_pad_zeros(
     bl->substr_of(old, 0, *length - back_copy);
     bl->append(tail);
     *length += back_pad;
-    if (end > o->onode.size && g_conf->bluestore_cache_tails) {
+    if (end >= o->onode.size && g_conf->bluestore_cache_tails) {
       o->tail_bl.clear();
       o->tail_bl.append(tail, 0, back_copy);
       o->tail_offset = end - back_copy;
@@ -5002,7 +5002,7 @@ void BlueStore::_pad_zeros_tail(
   bl->substr_of(old, 0, *length - back_copy);
   bl->append(tail);
   *length += back_pad;
-  if (end > o->onode.size && g_conf->bluestore_cache_tails) {
+  if (end >= o->onode.size && g_conf->bluestore_cache_tails) {
     o->tail_bl.clear();
     o->tail_bl.append(tail, 0, back_copy);
     o->tail_offset = end - back_copy;