[Qemu-devel] [PATCH 06/10] RFC: Add save dependency functions to qemu_file

[junyan . he]

From: Junyan He 

When we save snapshot, we need qemu_file to support save dependency
operations. It should call brv_driver's save dependency functions
to implement these operations.

Signed-off-by: Junyan He 
---
 migration/qemu-file.c | 61 +++
 migration/qemu-file.h | 14 
 migration/savevm.c| 33 +---
 3 files changed, 105 insertions(+), 3 deletions(-)

diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 2ab2bf3..9d2a39a 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -46,10 +46,13 @@ struct QEMUFile {
 int buf_index;
 int buf_size; /* 0 when writing */
 uint8_t buf[IO_BUF_SIZE];
+char ref_name_str[128]; /* maybe snapshot id */
 
 DECLARE_BITMAP(may_free, MAX_IOV_SIZE);
 struct iovec iov[MAX_IOV_SIZE];
 unsigned int iovcnt;
+bool support_dependency;
+int32_t dependency_aligment;
 
 int last_error;
 };
@@ -745,3 +748,61 @@ void qemu_file_set_blocking(QEMUFile *f, bool block)
 f->ops->set_blocking(f->opaque, block);
 }
 }
+
+void qemu_file_set_support_dependency(QEMUFile *f, int32_t alignment)
+{
+f->dependency_aligment = alignment;
+f->support_dependency = true;
+}
+
+bool qemu_file_is_support_dependency(QEMUFile *f, int32_t *alignment)
+{
+if (f->support_dependency && alignment) {
+*alignment = f->dependency_aligment;
+}
+
+return f->support_dependency;
+}
+
+/* This function set the reference name for snapshot usage. Sometimes it needs
+ * to depend on other snapshot's data to avoid redundance.
+ */
+bool qemu_file_set_ref_name(QEMUFile *f, const char *name)
+{
+if (strlen(name) + 1 > sizeof(f->ref_name_str)) {
+return false;
+}
+
+memcpy(f->ref_name_str, name, strlen(name) + 1);
+return true;
+}
+
+ssize_t qemu_file_save_dependency(QEMUFile *f, int64_t depend_offset,
+  int64_t size)
+{
+ssize_t ret;
+
+if (f->support_dependency == false) {
+return -1;
+}
+
+assert(f->ops->save_dependency);
+
+if (!QEMU_IS_ALIGNED(depend_offset, f->dependency_aligment)) {
+return -1;
+}
+
+qemu_fflush(f);
+
+if (!QEMU_IS_ALIGNED(f->pos, f->dependency_aligment)) {
+return -1;
+}
+
+ret = f->ops->save_dependency(f->opaque, f->ref_name_str,
+  depend_offset, size, f->pos);
+if (ret > 0) {
+f->pos += size;
+}
+
+return ret;
+}
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index aae4e5e..137b917 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -57,6 +57,14 @@ typedef ssize_t (QEMUFileWritevBufferFunc)(void *opaque, 
struct iovec *iov,
int iovcnt, int64_t pos);
 
 /*
+ * This function add reference to the dependency data in snapshot specified by
+ * ref_name_str to this file's offset
+ */
+typedef ssize_t (QEMUFileSaveDependencyFunc)(void *opaque, const char *name,
+ int64_t depend_offset,
+ int64_t offset, int64_t size);
+
+/*
  * This function provides hooks around different
  * stages of RAM migration.
  * 'opaque' is the backend specific data in QEMUFile
@@ -104,6 +112,7 @@ typedef struct QEMUFileOps {
 QEMUFileWritevBufferFunc *writev_buffer;
 QEMURetPathFunc *get_return_path;
 QEMUFileShutdownFunc *shut_down;
+QEMUFileSaveDependencyFunc *save_dependency;
 } QEMUFileOps;
 
 typedef struct QEMUFileHooks {
@@ -153,6 +162,11 @@ int qemu_file_shutdown(QEMUFile *f);
 QEMUFile *qemu_file_get_return_path(QEMUFile *f);
 void qemu_fflush(QEMUFile *f);
 void qemu_file_set_blocking(QEMUFile *f, bool block);
+bool qemu_file_set_ref_name(QEMUFile *f, const char *name);
+void qemu_file_set_support_dependency(QEMUFile *f, int32_t alignment);
+bool qemu_file_is_support_dependency(QEMUFile *f, int32_t *alignment);
+ssize_t qemu_file_save_dependency(QEMUFile *f, int64_t depend_offset,
+  int64_t size);
 
 size_t qemu_get_counted_string(QEMUFile *f, char buf[256]);
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 358c5b5..1bbd6aa 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -196,6 +196,20 @@ static ssize_t block_writev_buffer(void *opaque, struct 
iovec *iov, int iovcnt,
 return qiov.size;
 }
 
+static ssize_t block_save_dependency(void *opaque, const char *id_name,
+ int64_t depend_offset,
+ int64_t offset, int64_t size)
+{
+int ret = bdrv_snapshot_save_dependency(opaque, id_name,
+depend_offset, offset,
+size, NULL);
+if (ret < 0) {
+return ret;
+}
+
+return size;
+}
+
 static ssize_t block_get_buffer(void *opaque, 

[Qemu-devel] [PATCH 06/10] RFC: Add save dependency functions to qemu_file

[junyan . he]

From: Junyan He 

When we save snapshot, we need qemu_file to support save dependency
operations. It should call brv_driver's save dependency functions
to implement these operations.

Signed-off-by: Junyan He 
---
 migration/qemu-file.c | 61 +++
 migration/qemu-file.h | 14 
 migration/savevm.c| 33 +---
 3 files changed, 105 insertions(+), 3 deletions(-)

diff --git a/migration/qemu-file.c b/migration/qemu-file.c
index 2ab2bf3..9d2a39a 100644
--- a/migration/qemu-file.c
+++ b/migration/qemu-file.c
@@ -46,10 +46,13 @@ struct QEMUFile {
 int buf_index;
 int buf_size; /* 0 when writing */
 uint8_t buf[IO_BUF_SIZE];
+char ref_name_str[128]; /* maybe snapshot id */
 
 DECLARE_BITMAP(may_free, MAX_IOV_SIZE);
 struct iovec iov[MAX_IOV_SIZE];
 unsigned int iovcnt;
+bool support_dependency;
+int32_t dependency_aligment;
 
 int last_error;
 };
@@ -745,3 +748,61 @@ void qemu_file_set_blocking(QEMUFile *f, bool block)
 f->ops->set_blocking(f->opaque, block);
 }
 }
+
+void qemu_file_set_support_dependency(QEMUFile *f, int32_t alignment)
+{
+f->dependency_aligment = alignment;
+f->support_dependency = true;
+}
+
+bool qemu_file_is_support_dependency(QEMUFile *f, int32_t *alignment)
+{
+if (f->support_dependency && alignment) {
+*alignment = f->dependency_aligment;
+}
+
+return f->support_dependency;
+}
+
+/* This function set the reference name for snapshot usage. Sometimes it needs
+ * to depend on other snapshot's data to avoid redundance.
+ */
+bool qemu_file_set_ref_name(QEMUFile *f, const char *name)
+{
+if (strlen(name) + 1 > sizeof(f->ref_name_str)) {
+return false;
+}
+
+memcpy(f->ref_name_str, name, strlen(name) + 1);
+return true;
+}
+
+ssize_t qemu_file_save_dependency(QEMUFile *f, int64_t depend_offset,
+  int64_t size)
+{
+ssize_t ret;
+
+if (f->support_dependency == false) {
+return -1;
+}
+
+assert(f->ops->save_dependency);
+
+if (!QEMU_IS_ALIGNED(depend_offset, f->dependency_aligment)) {
+return -1;
+}
+
+qemu_fflush(f);
+
+if (!QEMU_IS_ALIGNED(f->pos, f->dependency_aligment)) {
+return -1;
+}
+
+ret = f->ops->save_dependency(f->opaque, f->ref_name_str,
+  depend_offset, size, f->pos);
+if (ret > 0) {
+f->pos += size;
+}
+
+return ret;
+}
diff --git a/migration/qemu-file.h b/migration/qemu-file.h
index aae4e5e..137b917 100644
--- a/migration/qemu-file.h
+++ b/migration/qemu-file.h
@@ -57,6 +57,14 @@ typedef ssize_t (QEMUFileWritevBufferFunc)(void *opaque, 
struct iovec *iov,
int iovcnt, int64_t pos);
 
 /*
+ * This function add reference to the dependency data in snapshot specified by
+ * ref_name_str to this file's offset
+ */
+typedef ssize_t (QEMUFileSaveDependencyFunc)(void *opaque, const char *name,
+ int64_t depend_offset,
+ int64_t offset, int64_t size);
+
+/*
  * This function provides hooks around different
  * stages of RAM migration.
  * 'opaque' is the backend specific data in QEMUFile
@@ -104,6 +112,7 @@ typedef struct QEMUFileOps {
 QEMUFileWritevBufferFunc *writev_buffer;
 QEMURetPathFunc *get_return_path;
 QEMUFileShutdownFunc *shut_down;
+QEMUFileSaveDependencyFunc *save_dependency;
 } QEMUFileOps;
 
 typedef struct QEMUFileHooks {
@@ -153,6 +162,11 @@ int qemu_file_shutdown(QEMUFile *f);
 QEMUFile *qemu_file_get_return_path(QEMUFile *f);
 void qemu_fflush(QEMUFile *f);
 void qemu_file_set_blocking(QEMUFile *f, bool block);
+bool qemu_file_set_ref_name(QEMUFile *f, const char *name);
+void qemu_file_set_support_dependency(QEMUFile *f, int32_t alignment);
+bool qemu_file_is_support_dependency(QEMUFile *f, int32_t *alignment);
+ssize_t qemu_file_save_dependency(QEMUFile *f, int64_t depend_offset,
+  int64_t size);
 
 size_t qemu_get_counted_string(QEMUFile *f, char buf[256]);
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 358c5b5..1bbd6aa 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -196,6 +196,20 @@ static ssize_t block_writev_buffer(void *opaque, struct 
iovec *iov, int iovcnt,
 return qiov.size;
 }
 
+static ssize_t block_save_dependency(void *opaque, const char *id_name,
+ int64_t depend_offset,
+ int64_t offset, int64_t size)
+{
+int ret = bdrv_snapshot_save_dependency(opaque, id_name,
+depend_offset, offset,
+size, NULL);
+if (ret < 0) {
+return ret;
+}
+
+return size;
+}
+
 static ssize_t block_get_buffer(void *opaque,