[Qemu-devel] [PATCH 01/10] snapshot: create helper to test that block drivers supports snapshots

[Denis V. Lunev]

The patch enforces proper locking for this operation.

Signed-off-by: Denis V. Lunev 
Reviewed-by: Greg Kurz 
Reviewed-by: Fam Zheng 
Reviewed-by: Stefan Hajnoczi 
CC: Juan Quintela 
CC: Kevin Wolf 
---
 block/snapshot.c | 24 
 include/block/snapshot.h |  8 
 migration/savevm.c   | 17 -
 3 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index 89500f2..d929d08 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -356,3 +356,27 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState 
*bs,
 
 return ret;
 }
+
+
+/* Group operations. All block drivers are involved.
+ * These functions will properly handle dataplane (take aio_context_acquire
+ * when appropriate for appropriate block drivers) */
+
+bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
+{
+bool ok = true;
+BlockDriverState *bs = NULL;
+
+while (ok && (bs = bdrv_next(bs))) {
+AioContext *ctx = bdrv_get_aio_context(bs);
+
+aio_context_acquire(ctx);
+if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
+ok = bdrv_can_snapshot(bs);
+}
+aio_context_release(ctx);
+}
+
+*first_bad_bs = bs;
+return ok;
+}
diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index 770d9bb..6195c9c 100644
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -75,4 +75,12 @@ int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
  const char *id_or_name,
  Error **errp);
+
+
+/* Group operations. All block drivers are involved.
+ * These functions will properly handle dataplane (take aio_context_acquire
+ * when appropriate for appropriate block drivers */
+
+bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs);
+
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index d90e228..4646aa1 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1958,19 +1958,10 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
 const char *name = qdict_get_try_str(qdict, "name");
 Error *local_err = NULL;
 
-/* Verify if there is a device that doesn't support snapshots and is 
writable */
-bs = NULL;
-while ((bs = bdrv_next(bs))) {
-
-if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
-continue;
-}
-
-if (!bdrv_can_snapshot(bs)) {
-monitor_printf(mon, "Device '%s' is writable but does not support 
snapshots.\n",
-   bdrv_get_device_name(bs));
-return;
-}
+if (!bdrv_all_can_snapshot()) {
+monitor_printf(mon, "Device '%s' is writable but does not "
+   "support snapshots.\n", bdrv_get_device_name(bs));
+return;
 }
 
 bs = find_vmstate_bs();
-- 
2.5.0

[Qemu-devel] [PATCH 01/10] snapshot: create helper to test that block drivers supports snapshots

[Denis V. Lunev]

The patch enforces proper locking for this operation.

Signed-off-by: Denis V. Lunev 
Reviewed-by: Greg Kurz 
CC: Juan Quintela 
CC: Stefan Hajnoczi 
CC: Kevin Wolf 
---
 block/snapshot.c | 24 
 include/block/snapshot.h |  8 
 migration/savevm.c   | 17 -
 3 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index 89500f2..d929d08 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -356,3 +356,27 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState 
*bs,
 
 return ret;
 }
+
+
+/* Group operations. All block drivers are involved.
+ * These functions will properly handle dataplane (take aio_context_acquire
+ * when appropriate for appropriate block drivers) */
+
+bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
+{
+bool ok = true;
+BlockDriverState *bs = NULL;
+
+while (ok && (bs = bdrv_next(bs))) {
+AioContext *ctx = bdrv_get_aio_context(bs);
+
+aio_context_acquire(ctx);
+if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
+ok = bdrv_can_snapshot(bs);
+}
+aio_context_release(ctx);
+}
+
+*first_bad_bs = bs;
+return ok;
+}
diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index 770d9bb..6195c9c 100644
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -75,4 +75,12 @@ int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
  const char *id_or_name,
  Error **errp);
+
+
+/* Group operations. All block drivers are involved.
+ * These functions will properly handle dataplane (take aio_context_acquire
+ * when appropriate for appropriate block drivers */
+
+bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs);
+
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index 9f2230f..c212288 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1290,19 +1290,10 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
 const char *name = qdict_get_try_str(qdict, "name");
 Error *local_err = NULL;
 
-/* Verify if there is a device that doesn't support snapshots and is 
writable */
-bs = NULL;
-while ((bs = bdrv_next(bs))) {
-
-if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
-continue;
-}
-
-if (!bdrv_can_snapshot(bs)) {
-monitor_printf(mon, "Device '%s' is writable but does not support 
snapshots.\n",
-   bdrv_get_device_name(bs));
-return;
-}
+if (!bdrv_all_can_snapshot()) {
+monitor_printf(mon, "Device '%s' is writable but does not "
+   "support snapshots.\n", bdrv_get_device_name(bs));
+return;
 }
 
 bs = find_vmstate_bs();
-- 
2.5.0

[Qemu-devel] [PATCH 01/10] snapshot: create helper to test that block drivers supports snapshots

[Denis V. Lunev]

The patch enforces proper locking for this operation.

Signed-off-by: Denis V. Lunev 
Reviewed-by: Greg Kurz 
CC: Juan Quintela 
CC: Stefan Hajnoczi 
CC: Kevin Wolf 
---
 block/snapshot.c | 24 
 include/block/snapshot.h |  8 
 migration/savevm.c   | 17 -
 3 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/block/snapshot.c b/block/snapshot.c
index 89500f2..d929d08 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -356,3 +356,27 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState 
*bs,
 
 return ret;
 }
+
+
+/* Group operations. All block drivers are involved.
+ * These functions will properly handle dataplane (take aio_context_acquire
+ * when appropriate for appropriate block drivers) */
+
+bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
+{
+bool ok = true;
+BlockDriverState *bs = NULL;
+
+while (ok && (bs = bdrv_next(bs))) {
+AioContext *ctx = bdrv_get_aio_context(bs);
+
+aio_context_acquire(ctx);
+if (bdrv_is_inserted(bs) && !bdrv_is_read_only(bs)) {
+ok = bdrv_can_snapshot(bs);
+}
+aio_context_release(ctx);
+}
+
+*first_bad_bs = bs;
+return ok;
+}
diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index 770d9bb..6195c9c 100644
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -75,4 +75,12 @@ int bdrv_snapshot_load_tmp(BlockDriverState *bs,
 int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
  const char *id_or_name,
  Error **errp);
+
+
+/* Group operations. All block drivers are involved.
+ * These functions will properly handle dataplane (take aio_context_acquire
+ * when appropriate for appropriate block drivers */
+
+bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs);
+
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index 9f2230f..c212288 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1290,19 +1290,10 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
 const char *name = qdict_get_try_str(qdict, "name");
 Error *local_err = NULL;
 
-/* Verify if there is a device that doesn't support snapshots and is 
writable */
-bs = NULL;
-while ((bs = bdrv_next(bs))) {
-
-if (!bdrv_is_inserted(bs) || bdrv_is_read_only(bs)) {
-continue;
-}
-
-if (!bdrv_can_snapshot(bs)) {
-monitor_printf(mon, "Device '%s' is writable but does not support 
snapshots.\n",
-   bdrv_get_device_name(bs));
-return;
-}
+if (!bdrv_all_can_snapshot()) {
+monitor_printf(mon, "Device '%s' is writable but does not "
+   "support snapshots.\n", bdrv_get_device_name(bs));
+return;
 }
 
 bs = find_vmstate_bs();
-- 
2.5.0