[PATCH 11/14] ram compress: Assert that the file buffer matches the result

[Lukas Straub]

Before this series, "nothing to send" was handled by the file buffer
being empty. Now it is tracked via param->result.

Assert that the file buffer state matches the result.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
---
 migration/qemu-file.c    | 11 +++++++++++
 migration/qemu-file.h    |  1 +
 migration/ram-compress.c |  5 +++++
 migration/ram.c          |  2 ++
 4 files changed, 19 insertions(+)

diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 102ab3b439..2b3f3f8549 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -887,6 +887,17 @@ int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src)
     return len;
 }

+/*
+ * Check if the writable buffer is empty
+ */
+
+bool qemu_file_buffer_empty(QEMUFile *file)
+{
+    assert(qemu_file_is_writable(file));
+
+    return !file->iovcnt;
+}
+
 /*
  * Get a string whose length is determined by a single preceding byte
  * A preallocated 256 byte buffer must be passed in.
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index 9d0155a2a1..15e5f189f0 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -113,6 +113,7 @@ size_t qemu_get_buffer_in_place(QEMUFile *f, uint8_t **buf, 
size_t size);
 ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream,
                                   const uint8_t *p, size_t size);
 int qemu_put_qemu_file(QEMUFile *f_des, QEMUFile *f_src);
+bool qemu_file_buffer_empty(QEMUFile *file);

 /*
  * Note that you can only peek continuous bytes from where the current pointer
diff --git a/migration/ram-compress.c b/migration/ram-compress.c
index f75b8c3079..b75a9d2b9a 100644
--- a/migration/ram-compress.c
+++ b/migration/ram-compress.c
@@ -193,6 +193,8 @@ static CompressResult do_compress_ram_page(QEMUFile *f, 
z_stream *stream,
     uint8_t *p = block->host + offset;
     int ret;

+    assert(qemu_file_buffer_empty(f));
+
     if (buffer_is_zero(p, TARGET_PAGE_SIZE)) {
         return RES_ZEROPAGE;
     }
@@ -207,6 +209,7 @@ static CompressResult do_compress_ram_page(QEMUFile *f, 
z_stream *stream,
     if (ret < 0) {
         qemu_file_set_error(migrate_get_current()->to_dst_file, ret);
         error_report("compressed data failed!");
+        qemu_fflush(f);
         return RES_NONE;
     }
     return RES_COMPRESS;
@@ -238,6 +241,7 @@ void flush_compressed_data(int 
(send_queued_data(CompressParam *)))
         if (!comp_param[idx].quit) {
             CompressParam *param = &comp_param[idx];
             send_queued_data(param);
+            assert(qemu_file_buffer_empty(param->file));
             compress_reset_result(param);
         }
         qemu_mutex_unlock(&comp_param[idx].mutex);
@@ -267,6 +271,7 @@ retry:
             qemu_mutex_lock(&param->mutex);
             param->done = false;
             send_queued_data(param);
+            assert(qemu_file_buffer_empty(param->file));
             compress_reset_result(param);
             set_compress_params(param, block, offset);

diff --git a/migration/ram.c b/migration/ram.c
index 5a2486bf89..7a8f540737 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1333,11 +1333,13 @@ static int send_queued_data(CompressParam *param)
     assert(block == pss->last_sent_block);

     if (param->result == RES_ZEROPAGE) {
+        assert(qemu_file_buffer_empty(param->file));
         len += save_page_header(pss, file, block, offset | RAM_SAVE_FLAG_ZERO);
         qemu_put_byte(file, 0);
         len += 1;
         ram_release_page(block->idstr, offset);
     } else if (param->result == RES_COMPRESS) {
+        assert(!qemu_file_buffer_empty(param->file));
         len += save_page_header(pss, file, block,
                                 offset | RAM_SAVE_FLAG_COMPRESS_PAGE);
         len += qemu_put_qemu_file(file, param->file);
--
2.30.2

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