os/bluestore: fix BufferSpace::read()

- we weren't reading from 'clean' buffers
- restructured loop a bit chasing another bug (but it ended up being
  in the caller)

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

diff --git a/src/os/bluestore/BlueStore.h b/src/os/bluestore/BlueStore.h
index 27ad14485711e3f246f938a766342a9d12b60dbe..583373625c38932b863b64aae77e3e0bdafdab1a 100644 (file)
--- a/src/os/bluestore/BlueStore.h
+++ b/src/os/bluestore/BlueStore.h
@@ -270,47 +270,47 @@ public:
       }
     }
 
-    void read(uint64_t offset, uint64_t length, BlueStore::ready_regions_t& res, interval_set<uint64_t>& res_intervals) {
+    void read(uint64_t offset, uint64_t length,
+             BlueStore::ready_regions_t& res,
+             interval_set<uint64_t>& res_intervals) {
       res.clear();
-      auto i = _data_lower_bound(offset);
       uint64_t end = offset + length;
-      while (i != buffer_map.end() && offset < end && i->first < end) {
+      for (auto i = _data_lower_bound(offset);
+          i != buffer_map.end() && offset < end && i->first < end;
+          ++i) {
        Buffer *b = i->second.get();
-        if(b->is_writing()) {
+       assert(b->end() > offset);
+        if (b->is_writing() || b->is_clean()) {
          if (b->offset < offset) {
-           uint64_t head = offset - b->offset;
-           uint64_t l = b->length > head ? b->length - head : 0;
-           l = MIN(length, b->length - head);
-           if(l>0){
-             res[offset].substr_of(b->data, head, l);
-             res_intervals.insert( offset, l);
-             offset += l;
-             length -= l;
-           }
-         } else if (b->offset > offset) {
-           uint64_t head = b->offset - offset;
-           uint64_t l = length > head ? length - head : 0;
-           l = MIN(l, b->length);
-           if(l>0){
-             res[b->offset].substr_of(b->data, 0, l);
-             res_intervals.insert(b->offset, l);
+           uint64_t skip = offset - b->offset;
+           uint64_t l = MIN(length, b->length - skip);
+           res[offset].substr_of(b->data, skip, l);
+           res_intervals.insert(offset, l);
+           offset += l;
+           length -= l;
+           continue;
+         }
+         if (b->offset > offset) {
+           uint64_t gap = b->offset - offset;
+           if (length <= gap) {
+             break;
            }
-           offset += l + head;
-           length -= l + head;
-         } else if(b->length != length) {
+           offset += gap;
+           length -= gap;
+         }
+         if (b->length > length) {
            uint64_t l = MIN(length, b->length);
-           res[b->offset].substr_of(b->data, 0, l);
-           res_intervals.insert(b->offset, l);
+           res[offset].substr_of(b->data, 0, l);
+           res_intervals.insert(offset, l);
            offset += l;
            length -= l;
          } else {
-           res[b->offset].append(b->data);
-           res_intervals.insert(b->offset, b->length);
+           res[offset].append(b->data);
+           res_intervals.insert(offset, b->length);
            offset += b->length;
            length -= b->length;
          }
        }
-       ++i;
       }
     }