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[Qemu-devel] [PATCH v7 2/3] block: Add node-name and to-replace-node-nam


From: Benoît Canet
Subject: [Qemu-devel] [PATCH v7 2/3] block: Add node-name and to-replace-node-name arguments to drive-mirror
Date: Mon, 9 Jun 2014 22:46:00 +0200

node-name gives a name to the created BDS and registers it in the node graph.

to-replace-node-name can be used when drive-mirror is called with sync=full.

The purpose of these fields is to be able to reconstruct and replace a broken
quorum file.

drive-mirror will bdrv_swap the new BDS named node-name with the one
pointed by to-replace-node-name when the mirroring is finished.

Signed-off-by: Benoit Canet <address@hidden>
---
 block.c                   | 27 +++++++++++++++++++++
 block/mirror.c            | 62 +++++++++++++++++++++++++++++++++++++----------
 blockdev.c                | 51 +++++++++++++++++++++++++++++++++++---
 hmp.c                     |  1 +
 include/block/block.h     |  5 ++++
 include/block/block_int.h |  4 ++-
 qapi/block-core.json      |  9 +++++++
 qmp-commands.hx           |  5 ++++
 8 files changed, 147 insertions(+), 17 deletions(-)

diff --git a/block.c b/block.c
index 17f763d..5c03c2b 100644
--- a/block.c
+++ b/block.c
@@ -5795,3 +5795,30 @@ bool bdrv_is_first_non_filter(BlockDriverState 
*candidate)
 
     return false;
 }
+
+BlockDriverState *check_to_replace_node(const char *to_replace_node_name,
+                                        Error **errp)
+{
+    BlockDriverState *to_replace_bs = bdrv_find_node(to_replace_node_name);
+    if (!to_replace_bs) {
+        error_setg(errp, "to-replace-node-name=%s not found",
+                   to_replace_node_name);
+        return NULL;
+    }
+
+    /* the code should only be able to replace the top first non filter
+     * node of the graph. For example the first BDS under a quorum.
+     */
+    if (!bdrv_is_first_non_filter(to_replace_bs)) {
+        error_set(errp, QERR_FEATURE_DISABLED,
+                  "drive-mirror and replace node-name");
+        return NULL;
+    }
+
+    if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
+        return NULL;
+    }
+
+    return to_replace_bs;
+}
+
diff --git a/block/mirror.c b/block/mirror.c
index 94c8661..68526ae 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -32,6 +32,12 @@ typedef struct MirrorBlockJob {
     RateLimit limit;
     BlockDriverState *target;
     BlockDriverState *base;
+    /* The name of the graph node to replace */
+    char *to_replace_node_name;
+    /* The block BDS to replace */
+    BlockDriverState *to_replace;
+    /* Used to block operations on the drive-mirror-replace target */
+    Error *replace_blocker;
     bool is_none_mode;
     BlockdevOnError on_source_error, on_target_error;
     bool synced;
@@ -490,10 +496,14 @@ immediate_exit:
     bdrv_release_dirty_bitmap(bs, s->dirty_bitmap);
     bdrv_iostatus_disable(s->target);
     if (s->should_complete && ret == 0) {
-        if (bdrv_get_flags(s->target) != bdrv_get_flags(s->common.bs)) {
-            bdrv_reopen(s->target, bdrv_get_flags(s->common.bs), NULL);
+        BlockDriverState *to_replace = s->common.bs;
+        if (s->to_replace) {
+            to_replace = s->to_replace;
         }
-        bdrv_swap(s->target, s->common.bs);
+        if (bdrv_get_flags(s->target) != bdrv_get_flags(to_replace)) {
+            bdrv_reopen(s->target, bdrv_get_flags(to_replace), NULL);
+        }
+        bdrv_swap(s->target, to_replace);
         if (s->common.driver->job_type == BLOCK_JOB_TYPE_COMMIT) {
             /* drop the bs loop chain formed by the swap: break the loop then
              * trigger the unref from the top one */
@@ -502,6 +512,11 @@ immediate_exit:
             bdrv_unref(p);
         }
     }
+    if (s->to_replace) {
+        bdrv_op_unblock_all(s->to_replace, s->replace_blocker);
+        error_free(s->replace_blocker);
+        bdrv_unref(s->to_replace);
+    }
     bdrv_unref(s->target);
     block_job_completed(&s->common, ret);
 }
@@ -540,6 +555,23 @@ static void mirror_complete(BlockJob *job, Error **errp)
         return;
     }
 
+    /* check the target bs is not block and block all operations on it */
+    if (s->to_replace_node_name) {
+        s->to_replace = check_to_replace_node(s->to_replace_node_name, errp);
+
+        if (!s->to_replace) {
+            return;
+        }
+
+        error_setg(&s->replace_blocker,
+                   "block device is in use by block-job-complete");
+        bdrv_op_block_all(s->to_replace, s->replace_blocker);
+        bdrv_ref(s->to_replace);
+
+        g_free(s->to_replace_node_name);
+        s->to_replace_node_name = NULL;
+    }
+
     s->should_complete = true;
     block_job_resume(job);
 }
@@ -562,14 +594,15 @@ static const BlockJobDriver commit_active_job_driver = {
 };
 
 static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
-                            int64_t speed, int64_t granularity,
-                            int64_t buf_size,
-                            BlockdevOnError on_source_error,
-                            BlockdevOnError on_target_error,
-                            BlockDriverCompletionFunc *cb,
-                            void *opaque, Error **errp,
-                            const BlockJobDriver *driver,
-                            bool is_none_mode, BlockDriverState *base)
+                             const char *to_replace_node_name,
+                             int64_t speed, int64_t granularity,
+                             int64_t buf_size,
+                             BlockdevOnError on_source_error,
+                             BlockdevOnError on_target_error,
+                             BlockDriverCompletionFunc *cb,
+                             void *opaque, Error **errp,
+                             const BlockJobDriver *driver,
+                             bool is_none_mode, BlockDriverState *base)
 {
     MirrorBlockJob *s;
 
@@ -600,6 +633,7 @@ static void mirror_start_job(BlockDriverState *bs, 
BlockDriverState *target,
         return;
     }
 
+    s->to_replace_node_name = g_strdup(to_replace_node_name);
     s->on_source_error = on_source_error;
     s->on_target_error = on_target_error;
     s->target = target;
@@ -621,6 +655,7 @@ static void mirror_start_job(BlockDriverState *bs, 
BlockDriverState *target,
 }
 
 void mirror_start(BlockDriverState *bs, BlockDriverState *target,
+                  const char *to_replace_node_name,
                   int64_t speed, int64_t granularity, int64_t buf_size,
                   MirrorSyncMode mode, BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
@@ -632,7 +667,8 @@ void mirror_start(BlockDriverState *bs, BlockDriverState 
*target,
 
     is_none_mode = mode == MIRROR_SYNC_MODE_NONE;
     base = mode == MIRROR_SYNC_MODE_TOP ? bs->backing_hd : NULL;
-    mirror_start_job(bs, target, speed, granularity, buf_size,
+    mirror_start_job(bs, target, to_replace_node_name,
+                     speed, granularity, buf_size,
                      on_source_error, on_target_error, cb, opaque, errp,
                      &mirror_job_driver, is_none_mode, base);
 }
@@ -680,7 +716,7 @@ void commit_active_start(BlockDriverState *bs, 
BlockDriverState *base,
     }
 
     bdrv_ref(base);
-    mirror_start_job(bs, base, speed, 0, 0,
+    mirror_start_job(bs, base, NULL, speed, 0, 0,
                      on_error, on_error, cb, opaque, &local_err,
                      &commit_active_job_driver, false, base);
     if (local_err) {
diff --git a/blockdev.c b/blockdev.c
index 4cbcc56..bccc2f6 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2106,6 +2106,9 @@ BlockDeviceInfoList *qmp_query_named_block_nodes(Error 
**errp)
 
 void qmp_drive_mirror(const char *device, const char *target,
                       bool has_format, const char *format,
+                      bool has_new_node_name, const char *new_node_name,
+                      bool has_to_replace_node_name,
+                      const char *to_replace_node_name,
                       enum MirrorSyncMode sync,
                       bool has_mode, enum NewImageMode mode,
                       bool has_speed, int64_t speed,
@@ -2119,6 +2122,7 @@ void qmp_drive_mirror(const char *device, const char 
*target,
     BlockDriverState *source, *target_bs;
     BlockDriver *drv = NULL;
     Error *local_err = NULL;
+    QDict *options = NULL;
     int flags;
     int64_t size;
     int ret;
@@ -2192,6 +2196,28 @@ void qmp_drive_mirror(const char *device, const char 
*target,
         return;
     }
 
+    if (has_to_replace_node_name) {
+        BlockDriverState *to_replace_bs;
+
+        if (!has_new_node_name) {
+            error_setg(errp, "a new-node-name must be provided when replacing 
a"
+                             " named node of the graph");
+            return;
+        }
+
+        to_replace_bs = check_to_replace_node(to_replace_node_name, errp);
+
+        if (!to_replace_bs) {
+            return;
+        }
+
+        if (size < bdrv_getlength(to_replace_bs)) {
+            error_setg(errp, "cannot replace to-replace-node-name image with a 
"
+                             "mirror image that would be smaller in size");
+            return;
+        }
+    }
+
     if ((sync == MIRROR_SYNC_MODE_FULL || !source)
         && mode != NEW_IMAGE_MODE_EXISTING)
     {
@@ -2220,18 +2246,37 @@ void qmp_drive_mirror(const char *device, const char 
*target,
         return;
     }
 
+    /* if we are planning to replace a graph node name the code should do a 
full
+     * mirror of the source image
+     */
+    if (has_to_replace_node_name && sync != MIRROR_SYNC_MODE_FULL) {
+        error_setg(errp,
+                   "to-replace-node-name can only be used with sync=full");
+        return;
+    }
+
+    if (has_new_node_name) {
+        options = qdict_new();
+        qdict_put(options, "node-name", qstring_from_str(new_node_name));
+    }
+
     /* Mirroring takes care of copy-on-write using the source's backing
      * file.
      */
     target_bs = NULL;
-    ret = bdrv_open(&target_bs, target, NULL, NULL, flags | BDRV_O_NO_BACKING,
-                    drv, &local_err);
+    ret = bdrv_open(&target_bs, target, NULL, options,
+                    flags | BDRV_O_NO_BACKING, drv, &local_err);
     if (ret < 0) {
         error_propagate(errp, local_err);
         return;
     }
 
-    mirror_start(bs, target_bs, speed, granularity, buf_size, sync,
+    /* pass the node name to replace to mirror start since it's loose coupling
+     * and will allow to check whether the node still exist at mirror 
completion
+     */
+    mirror_start(bs, target_bs,
+                 has_to_replace_node_name ? to_replace_node_name : NULL,
+                 speed, granularity, buf_size, sync,
                  on_source_error, on_target_error,
                  block_job_cb, bs, &local_err);
     if (local_err != NULL) {
diff --git a/hmp.c b/hmp.c
index ccc35d4..9a4b8da 100644
--- a/hmp.c
+++ b/hmp.c
@@ -930,6 +930,7 @@ void hmp_drive_mirror(Monitor *mon, const QDict *qdict)
     }
 
     qmp_drive_mirror(device, filename, !!format, format,
+                     false, NULL, false, NULL,
                      full ? MIRROR_SYNC_MODE_FULL : MIRROR_SYNC_MODE_TOP,
                      true, mode, false, 0, false, 0, false, 0,
                      false, 0, false, 0, &err);
diff --git a/include/block/block.h b/include/block/block.h
index 7d86e29..96afd01 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -179,6 +179,7 @@ typedef enum BlockOpType {
     BLOCK_OP_TYPE_MIRROR,
     BLOCK_OP_TYPE_RESIZE,
     BLOCK_OP_TYPE_STREAM,
+    BLOCK_OP_TYPE_REPLACE,
     BLOCK_OP_TYPE_MAX,
 } BlockOpType;
 
@@ -319,6 +320,10 @@ bool bdrv_recurse_is_first_non_filter(BlockDriverState *bs,
                                       BlockDriverState *candidate);
 bool bdrv_is_first_non_filter(BlockDriverState *candidate);
 
+/* check if a named node can be replaced when doing drive-mirror */
+BlockDriverState *check_to_replace_node(const char *to_replace_node_name,
+                                        Error **errp);
+
 /* async block I/O */
 typedef void BlockDriverDirtyHandler(BlockDriverState *bs, int64_t sector,
                                      int sector_num);
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 8d58334..ce65ed8 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -86,7 +86,6 @@ struct BlockDriver {
      */
     bool (*bdrv_recurse_is_first_non_filter)(BlockDriverState *bs,
                                              BlockDriverState *candidate);
-
     int (*bdrv_probe)(const uint8_t *buf, int buf_size, const char *filename);
     int (*bdrv_probe_device)(const char *filename);
 
@@ -492,6 +491,8 @@ void commit_active_start(BlockDriverState *bs, 
BlockDriverState *base,
  * mirror_start:
  * @bs: Block device to operate on.
  * @target: Block device to write to.
+ * @to_replace_node_name: Block graph node name to replace once the mirror is
+ *              done. Can only be used when full mirroring is selected.
  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
  * @granularity: The chosen granularity for the dirty bitmap.
  * @buf_size: The amount of data that can be in flight at one time.
@@ -508,6 +509,7 @@ void commit_active_start(BlockDriverState *bs, 
BlockDriverState *base,
  * @bs will be switched to read from @target.
  */
 void mirror_start(BlockDriverState *bs, BlockDriverState *target,
+                  const char *to_replace_node_name,
                   int64_t speed, int64_t granularity, int64_t buf_size,
                   MirrorSyncMode mode, BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
diff --git a/qapi/block-core.json b/qapi/block-core.json
index eec881b..23dcecd 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -769,6 +769,14 @@
 # @format: #optional the format of the new destination, default is to
 #          probe if @mode is 'existing', else the format of the source
 #
+# @new-node-name: #optional the new block driver state node name in the graph
+#                 (Since 2.1)
+#
+# @to-replace-node-name: #optional with sync=full graph node name to be
+#                        replaced by the new image when a whole image copy is
+#                        done. This can be used to repair broken Quorum files.
+#                        (Since 2.1)
+#
 # @mode: #optional whether and how QEMU should create a new image, default is
 #        'absolute-paths'.
 #
@@ -801,6 +809,7 @@
 ##
 { 'command': 'drive-mirror',
   'data': { 'device': 'str', 'target': 'str', '*format': 'str',
+            '*new-node-name': 'str', '*to-replace-node-name': 'str',
             'sync': 'MirrorSyncMode', '*mode': 'NewImageMode',
             '*speed': 'int', '*granularity': 'uint32',
             '*buf-size': 'int', '*on-source-error': 'BlockdevOnError',
diff --git a/qmp-commands.hx b/qmp-commands.hx
index d8aa4ed..bae74f5 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1293,6 +1293,7 @@ EQMP
     {
         .name       = "drive-mirror",
         .args_type  = "sync:s,device:B,target:s,speed:i?,mode:s?,format:s?,"
+                      "new-node-name:s?,to-replace-node-name:s?,"
                       "on-source-error:s?,on-target-error:s?,"
                       "granularity:i?,buf-size:i?",
         .mhandler.cmd_new = qmp_marshal_input_drive_mirror,
@@ -1314,6 +1315,10 @@ Arguments:
 - "device": device name to operate on (json-string)
 - "target": name of new image file (json-string)
 - "format": format of new image (json-string, optional)
+- "new-node-name": the name of the new block driver state in the node graph
+                   (json-string, optional)
+- "to-replace-node-name": the block driver node name to replace when finished
+                          (json-string, optional)
 - "mode": how an image file should be created into the target
   file/device (NewImageMode, optional, default 'absolute-paths')
 - "speed": maximum speed of the streaming job, in bytes per second
-- 
1.9.1




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