[Qemu-devel] [RFC PATCH 14/36] stream: add on_error argument

[Paolo Bonzini]

This patch adds support for error management to streaming.

Signed-off-by: Paolo Bonzini <address@hidden>
---
 block/stream.c   |   28 +++++++++++++++++++++++++++-
 block_int.h      |    3 ++-
 blockdev.c       |   11 ++++++++---
 hmp.c            |    3 ++-
 qapi-schema.json |    9 ++++++---
 qmp-commands.hx  |    2 +-
 6 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/block/stream.c b/block/stream.c
index b3ede44..270c8d8 100644
--- a/block/stream.c
+++ b/block/stream.c
@@ -31,6 +31,7 @@ typedef struct StreamBlockJob {
     BlockJob common;
     RateLimit limit;
     BlockDriverState *base;
+    BlockdevOnError on_error;
     char backing_file_id[1024];
 } StreamBlockJob;
 
@@ -78,6 +79,7 @@ static void coroutine_fn stream_run(void *opaque)
     BlockDriverState *bs = s->common.bs;
     BlockDriverState *base = s->base;
     int64_t sector_num, end;
+    int error = 0;
     int ret = 0;
     int n = 0;
     void *buf;
@@ -136,7 +138,19 @@ wait:
             ret = stream_populate(bs, sector_num, n, buf);
         }
         if (ret < 0) {
-            break;
+            BlockErrorAction action =
+                block_job_error_action(&s->common, s->common.bs, s->on_error,
+                                       true, -ret);
+            if (action == BDRV_ACTION_STOP) {
+                n = 0;
+                continue;
+            }
+            if (error == 0) {
+                error = ret;
+            }
+            if (action == BDRV_ACTION_REPORT) {
+                break;
+            }
         }
         ret = 0;
 
@@ -148,6 +162,9 @@ wait:
         bdrv_disable_copy_on_read(bs);
     }
 
+    /* Do not remove the backing file if an error was there but ignored.  */
+    ret = error;
+
     if (!block_job_is_cancelled(&s->common) && sector_num == end && ret == 0) {
         const char *base_id = NULL, *base_fmt = NULL;
         if (base) {
@@ -183,11 +200,19 @@ static BlockJobType stream_job_type = {
 
 void stream_start(BlockDriverState *bs, BlockDriverState *base,
                   const char *base_id, int64_t speed,
+                  BlockdevOnError on_error,
                   BlockDriverCompletionFunc *cb,
                   void *opaque, Error **errp)
 {
     StreamBlockJob *s;
 
+    if ((on_error == BLOCKDEV_ON_ERROR_STOP ||
+         on_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
+        !bdrv_iostatus_is_enabled(bs)) {
+        error_set(errp, QERR_INVALID_PARAMETER_COMBINATION);
+        return;
+    }
+
     s = block_job_create(&stream_job_type, bs, speed, cb, opaque, errp);
     if (!s) {
         return;
@@ -198,6 +223,7 @@ void stream_start(BlockDriverState *bs, BlockDriverState 
*base,
         pstrcpy(s->backing_file_id, sizeof(s->backing_file_id), base_id);
     }
 
+    s->on_error = on_error;
     s->common.co = qemu_coroutine_create(stream_run);
     trace_stream_start(bs, base, s, s->common.co, opaque);
     qemu_coroutine_enter(s->common.co, s);
diff --git a/block_int.h b/block_int.h
index 53fec71..731ef1a 100644
--- a/block_int.h
+++ b/block_int.h
@@ -290,6 +290,7 @@ void bdrv_emit_qmp_error_event(const BlockDriverState *bdrv,
  * @base_id: The file name that will be written to @bs as the new
  * backing file if the job completes.  Ignored if @base is %NULL.
  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
+ * @on_error: The action to take upon error.
  * @cb: Completion function for the job.
  * @opaque: Opaque pointer value passed to @cb.
  * @errp: Error object.
@@ -301,7 +302,7 @@ void bdrv_emit_qmp_error_event(const BlockDriverState *bdrv,
  * @base_id in the written image and to @base in the live BlockDriverState.
  */
 void stream_start(BlockDriverState *bs, BlockDriverState *base,
-                  const char *base_id, int64_t speed,
+                  const char *base_id, int64_t speed, BlockdevOnError on_error,
                   BlockDriverCompletionFunc *cb,
                   void *opaque, Error **errp);
 
diff --git a/blockdev.c b/blockdev.c
index 51bc488..adb21b9 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1092,13 +1092,18 @@ static void block_stream_cb(void *opaque, int ret)
 }
 
 void qmp_block_stream(const char *device, bool has_base,
-                      const char *base, bool has_speed,
-                      int64_t speed, Error **errp)
+                      const char *base, bool has_speed, int64_t speed,
+                      bool has_on_error, BlockdevOnError on_error,
+                      Error **errp)
 {
     BlockDriverState *bs;
     BlockDriverState *base_bs = NULL;
     Error *local_err = NULL;
 
+    if (!has_on_error) {
+        on_error = BLOCKDEV_ON_ERROR_REPORT;
+    }
+
     bs = bdrv_find(device);
     if (!bs) {
         error_set(errp, QERR_DEVICE_NOT_FOUND, device);
@@ -1114,7 +1119,7 @@ void qmp_block_stream(const char *device, bool has_base,
     }
 
     stream_start(bs, base_bs, base, has_speed ? speed : 0,
-                 block_stream_cb, bs, &local_err);
+                 on_error, block_stream_cb, bs, &local_err);
     if (error_is_set(&local_err)) {
         error_propagate(errp, local_err);
         return;
diff --git a/hmp.c b/hmp.c
index 9f6b255..b91fd32 100644
--- a/hmp.c
+++ b/hmp.c
@@ -843,7 +843,8 @@ void hmp_block_stream(Monitor *mon, const QDict *qdict)
     int64_t speed = qdict_get_try_int(qdict, "speed", 0);
 
     qmp_block_stream(device, base != NULL, base,
-                     qdict_haskey(qdict, "speed"), speed, &error);
+                     qdict_haskey(qdict, "speed"), speed,
+                     BLOCKDEV_ON_ERROR_REPORT, true, &error);
 
     hmp_handle_error(mon, &error);
 }
diff --git a/qapi-schema.json b/qapi-schema.json
index 0a1a35b..3c99dbb 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1650,6 +1650,8 @@
 #
 # @speed:  #optional the maximum speed, in bytes per second
 #
+# @on_error: #optional the action to take on an error (default report)
+#
 # Returns: Nothing on success
 #          If streaming is already active on this device, DeviceInUse
 #          If @device does not exist, DeviceNotFound
@@ -1657,10 +1659,11 @@
 #          If @base does not exist, BaseNotFound
 #          If @speed is invalid, InvalidParameter
 #
-# Since: 1.1
+# Since: 1.1, on_error since 1.2
 ##
-{ 'command': 'block-stream', 'data': { 'device': 'str', '*base': 'str',
-                                       '*speed': 'int' } }
+{ 'command': 'block-stream',
+  'data': { 'device': 'str', '*base': 'str', '*speed': 'int',
+            '*on_error': 'BlockdevOnError' } }
 
 ##
 # @block-job-set-speed:
diff --git a/qmp-commands.hx b/qmp-commands.hx
index f20754a..e2d77b6 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -718,7 +718,7 @@ EQMP
 
     {
         .name       = "block-stream",
-        .args_type  = "device:B,base:s?,speed:o?",
+        .args_type  = "device:B,base:s?,speed:o?,on_error:s?",
         .mhandler.cmd_new = qmp_marshal_input_block_stream,
     },
 
-- 
1.7.10.2