Fix a bs_read bug

src/blockstore/blockstore_flush.cpp

@@ -224,7 +224,7 @@ resume_1:
     }
     assert(!end_wr->next() && end_wr->flags == (BS_HEAP_BIG_WRITE|BS_HEAP_STABLE));
     clean_loc = end_wr->location;
-    if (bs->log_level > 9)
+    if (bs->log_level > 10)
         printf("Compacting %jx:%jx l%ju .. l%ju (last l%ju)\n", cur_oid.inode, cur_oid.stripe, end_wr->lsn, begin_wr->lsn, compact_lsn);
     flusher->active_flushers++;
     // Scan versions to flush
@@ -344,7 +344,7 @@ resume_24:
     }
     bs->heap->mark_object_compacted(cur_obj, compact_lsn);
     // Done
-    if (bs->log_level > 9)
+    if (bs->log_level > 10)
         printf("Compacted %jx:%jx l%ju (%d writes)\n", cur_oid.inode, cur_oid.stripe, compact_lsn, copy_count);
     flusher->compact_counter++;
     flusher->active_flushers--;

src/blockstore/blockstore_read.cpp

@@ -44,6 +44,7 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *op)
     if (!result_version)
     {
         // May happen if there are entries but all of them are > requested version
+        heap->unlock_entry(op->oid, PRIV(op)->lsn);
         op->version = 0;
         op->retval = -ENOENT;
         FINISH_OP(op);
@@ -62,6 +63,7 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *op)
     if (!PRIV(op)->pending_ops)
     {
         // everything is fulfilled from memory
+        heap->unlock_entry(op->oid, PRIV(op)->lsn);
         op->retval = op->len;
         free_read_buffers(rv);
         FINISH_OP(op);
@@ -115,10 +117,10 @@ uint32_t blockstore_impl_t::prepare_read(std::vector<copy_buffer_t> & read_vec,
 
 uint32_t blockstore_impl_t::prepare_read_with_bitmaps(std::vector<copy_buffer_t> & read_vec, heap_object_t *obj, heap_write_t *wr, uint32_t start, uint32_t end)
 {
-    // BIG_WRITEs contain a bitmap and we have to handle its holes at the upper level, especially with padded checksums
+    // BIG_WRITEs contain a bitmap and we have to handle its holes
     uint32_t res = 0;
     uint8_t *bmp = wr->get_int_bitmap(heap);
-    uint32_t bmp_start = 0, bmp_end = 0, bmp_size = dsk.data_block_size/dsk.bitmap_granularity;
+    uint32_t bmp_start = start/dsk.bitmap_granularity, bmp_end = bmp_start, bmp_size = end/dsk.bitmap_granularity;
     while (bmp_start < bmp_size)
     {
         while (bmp_end < bmp_size && !(bmp[bmp_end >> 3] & (1 << (bmp_end & 0x7))))

src/test/test_blockstore.cpp

@@ -194,6 +194,7 @@ static void test_simple()
     op.len = 128*1024;
     test.exec_op(&op);
     assert(op.retval == op.len);
+    assert(op.version == 1);
     uint8_t *cmp = (uint8_t*)memalign_or_die(MEM_ALIGNMENT, 128*1024);
     memset(cmp, 0, 128*1024);
     memset(cmp+16384, 0xaa, 4096);
@@ -204,6 +205,25 @@ static void test_simple()
         printf("read returned incorrect data\n");
         abort();
     }
+
+    // Zero-length read
+    printf("reading 0-0\n");
+    op.version = UINT64_MAX;
+    op.offset = 0;
+    op.len = 0;
+    test.exec_op(&op);
+    assert(op.retval == op.len);
+    assert(op.version == 1);
+
+    // Small read
+    printf("reading 16K-24K\n");
+    op.version = UINT64_MAX;
+    op.offset = 16*1024;
+    op.len = 8*1024;
+    test.exec_op(&op);
+    assert(op.retval == op.len);
+    assert(!memcmp(op.buf, cmp+16*1024, 8*1024));
+
     free(cmp);
 
     free(op.buf);