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* [PATCH v2 0/3] migration: Make save/load_snapshot() return boolean
@ 2020-10-12 12:27 Philippe Mathieu-Daudé
  2020-10-12 12:27 ` [PATCH v2 1/3] block: push error reporting into bdrv_all_*_snapshot functions Philippe Mathieu-Daudé
                   ` (2 more replies)
  0 siblings, 3 replies; 8+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-10-12 12:27 UTC (permalink / raw)
  To: qemu-devel
  Cc: Kevin Wolf, Daniel P . Berrangé,
	qemu-block, Juan Quintela, Dr. David Alan Gilbert, Max Reitz,
	Pavel Dovgalyuk, Paolo Bonzini, Philippe Mathieu-Daudé

Since v1:
- Initialize variables in first patch (Max)
- Added Pavel's A-b tag

I had a pair of patches making save_snapshot/load_snapshot()
return a boolean (like Markus recent qdev/QOM cleanup), then
realized Daniel already has series changing migration/, so I
rebased my patches in the first part of his v6 series:
"migration: bring improved savevm/loadvm/delvm to QMP"
https://lists.gnu.org/archive/html/qemu-devel/2020-10/msg02158.html

I included patch #1/#3 from Daniel, #2 is my first patch,
and my second patch is squashed with Daniel's #3.

Daniel if you find these patches worthwhile, please consider them
while merging your series (or respining).

Regards,

Phil.

Daniel P. Berrangé (2):
  block: push error reporting into bdrv_all_*_snapshot functions
  migration: stop returning errno from load_snapshot()

Philippe Mathieu-Daudé (1):
  migration: Make save_snapshot() return bool, not 0/-1

 include/block/snapshot.h       | 14 +++----
 include/migration/snapshot.h   | 18 +++++++-
 block/monitor/block-hmp-cmds.c |  7 ++--
 block/snapshot.c               | 77 +++++++++++++++++-----------------
 migration/savevm.c             | 72 ++++++++++++-------------------
 monitor/hmp-cmds.c             |  9 +---
 replay/replay-debugging.c      |  6 +--
 replay/replay-snapshot.c       |  4 +-
 softmmu/vl.c                   |  2 +-
 tests/qemu-iotests/267.out     | 10 ++---
 10 files changed, 105 insertions(+), 114 deletions(-)

-- 
2.26.2




^ permalink raw reply	[flat|nested] 8+ messages in thread
* [PATCH v2 1/3] block: push error reporting into bdrv_all_*_snapshot functions
  2020-10-12 12:27 [PATCH v2 0/3] migration: Make save/load_snapshot() return boolean Philippe Mathieu-Daudé
@ 2020-10-12 12:27 ` Philippe Mathieu-Daudé
  2020-10-12 15:21   ` Max Reitz
  2020-10-12 12:27 ` [PATCH v2 2/3] migration: Make save_snapshot() return bool, not 0/-1 Philippe Mathieu-Daudé
  2020-10-12 12:27 ` [PATCH v2 3/3] migration: stop returning errno from load_snapshot() Philippe Mathieu-Daudé
  2 siblings, 1 reply; 8+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-10-12 12:27 UTC (permalink / raw)
  To: qemu-devel
  Cc: Kevin Wolf, Daniel P . Berrangé,
	qemu-block, Juan Quintela, Dr. David Alan Gilbert, Max Reitz,
	Pavel Dovgalyuk, Paolo Bonzini, Philippe Mathieu-Daudé

From: Daniel P. Berrangé <berrange@redhat.com>

The bdrv_all_*_snapshot functions return a BlockDriverState pointer
for the invalid backend, which the callers then use to report an
error message. In some cases multiple callers are reporting the
same error message, but with slightly different text. In the future
there will be more error scenarios for some of these methods, which
will benefit from fine grained error message reporting. So it is
helpful to push error reporting down a level.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[PMD: Initialize variables]
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/block/snapshot.h       | 14 +++----
 block/monitor/block-hmp-cmds.c |  7 ++--
 block/snapshot.c               | 77 +++++++++++++++++-----------------
 migration/savevm.c             | 37 +++++-----------
 monitor/hmp-cmds.c             |  7 +---
 replay/replay-debugging.c      |  4 +-
 tests/qemu-iotests/267.out     | 10 ++---
 7 files changed, 67 insertions(+), 89 deletions(-)

diff --git a/include/block/snapshot.h b/include/block/snapshot.h
index b0fe42993dc..5cb2b696ad0 100644
--- a/include/block/snapshot.h
+++ b/include/block/snapshot.h
@@ -77,17 +77,15 @@ int bdrv_snapshot_load_tmp_by_id_or_name(BlockDriverState *bs,
  * 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);
-int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bsd_bs,
-                             Error **errp);
-int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
-                           Error **errp);
-int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs);
+bool bdrv_all_can_snapshot(Error **errp);
+int bdrv_all_delete_snapshot(const char *name, Error **errp);
+int bdrv_all_goto_snapshot(const char *name, Error **errp);
+int bdrv_all_find_snapshot(const char *name, Error **errp);
 int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
                              BlockDriverState *vm_state_bs,
                              uint64_t vm_state_size,
-                             BlockDriverState **first_bad_bs);
+                             Error **errp);
 
-BlockDriverState *bdrv_all_find_vmstate_bs(void);
+BlockDriverState *bdrv_all_find_vmstate_bs(Error **errp);
 
 #endif
diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c
index d15a2be827b..548bb6b5e3f 100644
--- a/block/monitor/block-hmp-cmds.c
+++ b/block/monitor/block-hmp-cmds.c
@@ -899,10 +899,11 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
 
     ImageEntry *image_entry, *next_ie;
     SnapshotEntry *snapshot_entry;
+    Error *err = NULL;
 
-    bs = bdrv_all_find_vmstate_bs();
+    bs = bdrv_all_find_vmstate_bs(&err);
     if (!bs) {
-        monitor_printf(mon, "No available block device supports snapshots\n");
+        error_report_err(err);
         return;
     }
     aio_context = bdrv_get_aio_context(bs);
@@ -952,7 +953,7 @@ void hmp_info_snapshots(Monitor *mon, const QDict *qdict)
     total = 0;
     for (i = 0; i < nb_sns; i++) {
         SnapshotEntry *next_sn;
-        if (bdrv_all_find_snapshot(sn_tab[i].name, &bs1) == 0) {
+        if (bdrv_all_find_snapshot(sn_tab[i].name, NULL) == 0) {
             global_snapshots[total] = i;
             total++;
             QTAILQ_FOREACH(image_entry, &image_list, next) {
diff --git a/block/snapshot.c b/block/snapshot.c
index a2bf3a54eb0..482e3fc7b72 100644
--- a/block/snapshot.c
+++ b/block/snapshot.c
@@ -462,14 +462,14 @@ static bool bdrv_all_snapshots_includes_bs(BlockDriverState *bs)
  * 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 bdrv_all_can_snapshot(Error **errp)
 {
-    bool ok = true;
     BlockDriverState *bs;
     BdrvNextIterator it;
 
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         AioContext *ctx = bdrv_get_aio_context(bs);
+        bool ok = true;
 
         aio_context_acquire(ctx);
         if (bdrv_all_snapshots_includes_bs(bs)) {
@@ -477,26 +477,25 @@ bool bdrv_all_can_snapshot(BlockDriverState **first_bad_bs)
         }
         aio_context_release(ctx);
         if (!ok) {
+            error_setg(errp, "Device '%s' is writable but does not support "
+                       "snapshots", bdrv_get_device_or_node_name(bs));
             bdrv_next_cleanup(&it);
-            goto fail;
+            return false;
         }
     }
 
-fail:
-    *first_bad_bs = bs;
-    return ok;
+    return true;
 }
 
-int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
-                             Error **errp)
+int bdrv_all_delete_snapshot(const char *name, Error **errp)
 {
-    int ret = 0;
     BlockDriverState *bs;
     BdrvNextIterator it;
     QEMUSnapshotInfo sn1, *snapshot = &sn1;
 
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         AioContext *ctx = bdrv_get_aio_context(bs);
+        int ret = 0;
 
         aio_context_acquire(ctx);
         if (bdrv_all_snapshots_includes_bs(bs) &&
@@ -507,26 +506,25 @@ int bdrv_all_delete_snapshot(const char *name, BlockDriverState **first_bad_bs,
         }
         aio_context_release(ctx);
         if (ret < 0) {
+            error_prepend(errp, "Could not delete snapshot '%s' on '%s': ",
+                          name, bdrv_get_device_or_node_name(bs));
             bdrv_next_cleanup(&it);
-            goto fail;
+            return -1;
         }
     }
 
-fail:
-    *first_bad_bs = bs;
-    return ret;
+    return 0;
 }
 
 
-int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
-                           Error **errp)
+int bdrv_all_goto_snapshot(const char *name, Error **errp)
 {
-    int ret = 0;
     BlockDriverState *bs;
     BdrvNextIterator it;
 
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         AioContext *ctx = bdrv_get_aio_context(bs);
+        int ret = 0;
 
         aio_context_acquire(ctx);
         if (bdrv_all_snapshots_includes_bs(bs)) {
@@ -534,75 +532,75 @@ int bdrv_all_goto_snapshot(const char *name, BlockDriverState **first_bad_bs,
         }
         aio_context_release(ctx);
         if (ret < 0) {
+            error_prepend(errp, "Could not load snapshot '%s' on '%s': ",
+                          name, bdrv_get_device_or_node_name(bs));
             bdrv_next_cleanup(&it);
-            goto fail;
+            return -1;
         }
     }
 
-fail:
-    *first_bad_bs = bs;
-    return ret;
+    return 0;
 }
 
-int bdrv_all_find_snapshot(const char *name, BlockDriverState **first_bad_bs)
+int bdrv_all_find_snapshot(const char *name, Error **errp)
 {
     QEMUSnapshotInfo sn;
-    int err = 0;
     BlockDriverState *bs;
     BdrvNextIterator it;
 
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         AioContext *ctx = bdrv_get_aio_context(bs);
+        int ret = 0;
 
         aio_context_acquire(ctx);
         if (bdrv_all_snapshots_includes_bs(bs)) {
-            err = bdrv_snapshot_find(bs, &sn, name);
+            ret = bdrv_snapshot_find(bs, &sn, name);
         }
         aio_context_release(ctx);
-        if (err < 0) {
+        if (ret < 0) {
+            error_setg(errp, "Could not find snapshot '%s' on '%s'",
+                       name, bdrv_get_device_or_node_name(bs));
             bdrv_next_cleanup(&it);
-            goto fail;
+            return -1;
         }
     }
 
-fail:
-    *first_bad_bs = bs;
-    return err;
+    return 0;
 }
 
 int bdrv_all_create_snapshot(QEMUSnapshotInfo *sn,
                              BlockDriverState *vm_state_bs,
                              uint64_t vm_state_size,
-                             BlockDriverState **first_bad_bs)
+                             Error **errp)
 {
-    int err = 0;
     BlockDriverState *bs;
     BdrvNextIterator it;
 
     for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
         AioContext *ctx = bdrv_get_aio_context(bs);
+        int ret = 0;
 
         aio_context_acquire(ctx);
         if (bs == vm_state_bs) {
             sn->vm_state_size = vm_state_size;
-            err = bdrv_snapshot_create(bs, sn);
+            ret = bdrv_snapshot_create(bs, sn);
         } else if (bdrv_all_snapshots_includes_bs(bs)) {
             sn->vm_state_size = 0;
-            err = bdrv_snapshot_create(bs, sn);
+            ret = bdrv_snapshot_create(bs, sn);
         }
         aio_context_release(ctx);
-        if (err < 0) {
+        if (ret < 0) {
+            error_setg(errp, "Could not create snapshot '%s' on '%s'",
+                       sn->name, bdrv_get_device_or_node_name(bs));
             bdrv_next_cleanup(&it);
-            goto fail;
+            return -1;
         }
     }
 
-fail:
-    *first_bad_bs = bs;
-    return err;
+    return 0;
 }
 
-BlockDriverState *bdrv_all_find_vmstate_bs(void)
+BlockDriverState *bdrv_all_find_vmstate_bs(Error **errp)
 {
     BlockDriverState *bs;
     BdrvNextIterator it;
@@ -620,5 +618,8 @@ BlockDriverState *bdrv_all_find_vmstate_bs(void)
             break;
         }
     }
+    if (!bs) {
+        error_setg(errp, "No block device supports snapshots");
+    }
     return bs;
 }
diff --git a/migration/savevm.c b/migration/savevm.c
index d2e141f7b1d..a52da440f4b 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2660,7 +2660,7 @@ int qemu_load_device_state(QEMUFile *f)
 
 int save_snapshot(const char *name, Error **errp)
 {
-    BlockDriverState *bs, *bs1;
+    BlockDriverState *bs;
     QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
     int ret = -1, ret2;
     QEMUFile *f;
@@ -2680,25 +2680,19 @@ int save_snapshot(const char *name, Error **errp)
         return ret;
     }
 
-    if (!bdrv_all_can_snapshot(&bs)) {
-        error_setg(errp, "Device '%s' is writable but does not support "
-                   "snapshots", bdrv_get_device_or_node_name(bs));
+    if (!bdrv_all_can_snapshot(errp)) {
         return ret;
     }
 
     /* Delete old snapshots of the same name */
     if (name) {
-        ret = bdrv_all_delete_snapshot(name, &bs1, errp);
-        if (ret < 0) {
-            error_prepend(errp, "Error while deleting snapshot on device "
-                          "'%s': ", bdrv_get_device_or_node_name(bs1));
+        if (bdrv_all_delete_snapshot(name, errp) < 0) {
             return ret;
         }
     }
 
-    bs = bdrv_all_find_vmstate_bs();
+    bs = bdrv_all_find_vmstate_bs(errp);
     if (bs == NULL) {
-        error_setg(errp, "No block device can accept snapshots");
         return ret;
     }
     aio_context = bdrv_get_aio_context(bs);
@@ -2768,10 +2762,8 @@ int save_snapshot(const char *name, Error **errp)
     aio_context_release(aio_context);
     aio_context = NULL;
 
-    ret = bdrv_all_create_snapshot(sn, bs, vm_state_size, &bs);
+    ret = bdrv_all_create_snapshot(sn, bs, vm_state_size, errp);
     if (ret < 0) {
-        error_setg(errp, "Error while creating snapshot on '%s'",
-                   bdrv_get_device_or_node_name(bs));
         goto the_end;
     }
 
@@ -2874,30 +2866,23 @@ void qmp_xen_load_devices_state(const char *filename, Error **errp)
 
 int load_snapshot(const char *name, Error **errp)
 {
-    BlockDriverState *bs, *bs_vm_state;
+    BlockDriverState *bs_vm_state;
     QEMUSnapshotInfo sn;
     QEMUFile *f;
     int ret;
     AioContext *aio_context;
     MigrationIncomingState *mis = migration_incoming_get_current();
 
-    if (!bdrv_all_can_snapshot(&bs)) {
-        error_setg(errp,
-                   "Device '%s' is writable but does not support snapshots",
-                   bdrv_get_device_or_node_name(bs));
+    if (!bdrv_all_can_snapshot(errp)) {
         return -ENOTSUP;
     }
-    ret = bdrv_all_find_snapshot(name, &bs);
+    ret = bdrv_all_find_snapshot(name, errp);
     if (ret < 0) {
-        error_setg(errp,
-                   "Device '%s' does not have the requested snapshot '%s'",
-                   bdrv_get_device_or_node_name(bs), name);
         return ret;
     }
 
-    bs_vm_state = bdrv_all_find_vmstate_bs();
+    bs_vm_state = bdrv_all_find_vmstate_bs(errp);
     if (!bs_vm_state) {
-        error_setg(errp, "No block device supports snapshots");
         return -ENOTSUP;
     }
     aio_context = bdrv_get_aio_context(bs_vm_state);
@@ -2923,10 +2908,8 @@ int load_snapshot(const char *name, Error **errp)
     /* Flush all IO requests so they don't interfere with the new state.  */
     bdrv_drain_all_begin();
 
-    ret = bdrv_all_goto_snapshot(name, &bs, errp);
+    ret = bdrv_all_goto_snapshot(name, errp);
     if (ret < 0) {
-        error_prepend(errp, "Could not load snapshot '%s' on '%s': ",
-                      name, bdrv_get_device_or_node_name(bs));
         goto err_drain;
     }
 
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index 9789f4277f5..f48173820ff 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -1139,15 +1139,10 @@ void hmp_savevm(Monitor *mon, const QDict *qdict)
 
 void hmp_delvm(Monitor *mon, const QDict *qdict)
 {
-    BlockDriverState *bs;
     Error *err = NULL;
     const char *name = qdict_get_str(qdict, "name");
 
-    if (bdrv_all_delete_snapshot(name, &bs, &err) < 0) {
-        error_prepend(&err,
-                      "deleting snapshot on device '%s': ",
-                      bdrv_get_device_name(bs));
-    }
+    bdrv_all_delete_snapshot(name, &err);
     hmp_handle_error(mon, err);
 }
 
diff --git a/replay/replay-debugging.c b/replay/replay-debugging.c
index ee9e86daa9b..8785489c02d 100644
--- a/replay/replay-debugging.c
+++ b/replay/replay-debugging.c
@@ -149,7 +149,7 @@ static char *replay_find_nearest_snapshot(int64_t icount,
 
     *snapshot_icount = -1;
 
-    bs = bdrv_all_find_vmstate_bs();
+    bs = bdrv_all_find_vmstate_bs(NULL);
     if (!bs) {
         goto fail;
     }
@@ -160,7 +160,7 @@ static char *replay_find_nearest_snapshot(int64_t icount,
     aio_context_release(aio_context);
 
     for (i = 0; i < nb_sns; i++) {
-        if (bdrv_all_find_snapshot(sn_tab[i].name, &bs) == 0) {
+        if (bdrv_all_find_snapshot(sn_tab[i].name, NULL) == 0) {
             if (sn_tab[i].icount != -1ULL
                 && sn_tab[i].icount <= icount
                 && (!nearest || nearest->icount < sn_tab[i].icount)) {
diff --git a/tests/qemu-iotests/267.out b/tests/qemu-iotests/267.out
index 27471ffae83..6149029b25d 100644
--- a/tests/qemu-iotests/267.out
+++ b/tests/qemu-iotests/267.out
@@ -6,9 +6,9 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
 Testing:
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) savevm snap0
-Error: No block device can accept snapshots
+Error: No block device supports snapshots
 (qemu) info snapshots
-No available block device supports snapshots
+No block device supports snapshots
 (qemu) loadvm snap0
 Error: No block device supports snapshots
 (qemu) quit
@@ -22,7 +22,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) savevm snap0
 Error: Device 'none0' is writable but does not support snapshots
 (qemu) info snapshots
-No available block device supports snapshots
+No block device supports snapshots
 (qemu) loadvm snap0
 Error: Device 'none0' is writable but does not support snapshots
 (qemu) quit
@@ -58,7 +58,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) savevm snap0
 Error: Device 'virtio0' is writable but does not support snapshots
 (qemu) info snapshots
-No available block device supports snapshots
+No block device supports snapshots
 (qemu) loadvm snap0
 Error: Device 'virtio0' is writable but does not support snapshots
 (qemu) quit
@@ -83,7 +83,7 @@ QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) savevm snap0
 Error: Device 'file' is writable but does not support snapshots
 (qemu) info snapshots
-No available block device supports snapshots
+No block device supports snapshots
 (qemu) loadvm snap0
 Error: Device 'file' is writable but does not support snapshots
 (qemu) quit
-- 
2.26.2



^ permalink raw reply related	[flat|nested] 8+ messages in thread
* [PATCH v2 2/3] migration: Make save_snapshot() return bool, not 0/-1
  2020-10-12 12:27 [PATCH v2 0/3] migration: Make save/load_snapshot() return boolean Philippe Mathieu-Daudé
  2020-10-12 12:27 ` [PATCH v2 1/3] block: push error reporting into bdrv_all_*_snapshot functions Philippe Mathieu-Daudé
@ 2020-10-12 12:27 ` Philippe Mathieu-Daudé
  2020-10-21  9:56   ` Daniel P. Berrangé
  2020-10-12 12:27 ` [PATCH v2 3/3] migration: stop returning errno from load_snapshot() Philippe Mathieu-Daudé
  2 siblings, 1 reply; 8+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-10-12 12:27 UTC (permalink / raw)
  To: qemu-devel
  Cc: Kevin Wolf, Daniel P . Berrangé,
	qemu-block, Juan Quintela, Dr. David Alan Gilbert, Max Reitz,
	Pavel Dovgalyuk, Pavel Dovgalyuk, Paolo Bonzini,
	Philippe Mathieu-Daudé

Just for consistency, following the example documented since
commit e3fe3988d7 ("error: Document Error API usage rules"),
return a boolean value indicating an error is set or not.

Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/migration/snapshot.h |  9 ++++++++-
 migration/savevm.c           | 16 ++++++++--------
 replay/replay-debugging.c    |  2 +-
 replay/replay-snapshot.c     |  2 +-
 4 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
index c85b6ec75b7..a40c34307b5 100644
--- a/include/migration/snapshot.h
+++ b/include/migration/snapshot.h
@@ -15,7 +15,14 @@
 #ifndef QEMU_MIGRATION_SNAPSHOT_H
 #define QEMU_MIGRATION_SNAPSHOT_H
 
-int save_snapshot(const char *name, Error **errp);
+/**
+ * save_snapshot: Save a snapshot.
+ * @name: path to snapshot
+ * @errp: pointer to error object
+ * On success, return %true.
+ * On failure, store an error through @errp and return %false.
+ */
+bool save_snapshot(const char *name, Error **errp);
 int load_snapshot(const char *name, Error **errp);
 
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index a52da440f4b..fd2e5e8b663 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2658,7 +2658,7 @@ int qemu_load_device_state(QEMUFile *f)
     return 0;
 }
 
-int save_snapshot(const char *name, Error **errp)
+bool save_snapshot(const char *name, Error **errp)
 {
     BlockDriverState *bs;
     QEMUSnapshotInfo sn1, *sn = &sn1, old_sn1, *old_sn = &old_sn1;
@@ -2671,29 +2671,29 @@ int save_snapshot(const char *name, Error **errp)
     AioContext *aio_context;
 
     if (migration_is_blocked(errp)) {
-        return ret;
+        return false;
     }
 
     if (!replay_can_snapshot()) {
         error_setg(errp, "Record/replay does not allow making snapshot "
                    "right now. Try once more later.");
-        return ret;
+        return false;
     }
 
     if (!bdrv_all_can_snapshot(errp)) {
-        return ret;
+        return false;
     }
 
     /* Delete old snapshots of the same name */
     if (name) {
         if (bdrv_all_delete_snapshot(name, errp) < 0) {
-            return ret;
+            return false;
         }
     }
 
     bs = bdrv_all_find_vmstate_bs(errp);
     if (bs == NULL) {
-        return ret;
+        return false;
     }
     aio_context = bdrv_get_aio_context(bs);
 
@@ -2702,7 +2702,7 @@ int save_snapshot(const char *name, Error **errp)
     ret = global_state_store();
     if (ret) {
         error_setg(errp, "Error saving global state");
-        return ret;
+        return false;
     }
     vm_stop(RUN_STATE_SAVE_VM);
 
@@ -2779,7 +2779,7 @@ int save_snapshot(const char *name, Error **errp)
     if (saved_vm_running) {
         vm_start();
     }
-    return ret;
+    return ret == 0;
 }
 
 void qmp_xen_save_devices_state(const char *filename, bool has_live, bool live,
diff --git a/replay/replay-debugging.c b/replay/replay-debugging.c
index 8785489c02d..5458a73fced 100644
--- a/replay/replay-debugging.c
+++ b/replay/replay-debugging.c
@@ -327,7 +327,7 @@ void replay_gdb_attached(void)
      */
     if (replay_mode == REPLAY_MODE_PLAY
         && !replay_snapshot) {
-        if (save_snapshot("start_debugging", NULL) != 0) {
+        if (!save_snapshot("start_debugging", NULL)) {
             /* Can't create the snapshot. Continue conventional debugging. */
         }
     }
diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
index e26fa4c892e..4f2560d1568 100644
--- a/replay/replay-snapshot.c
+++ b/replay/replay-snapshot.c
@@ -77,7 +77,7 @@ void replay_vmstate_init(void)
 
     if (replay_snapshot) {
         if (replay_mode == REPLAY_MODE_RECORD) {
-            if (save_snapshot(replay_snapshot, &err) != 0) {
+            if (!save_snapshot(replay_snapshot, &err)) {
                 error_report_err(err);
                 error_report("Could not create snapshot for icount record");
                 exit(1);
-- 
2.26.2



^ permalink raw reply related	[flat|nested] 8+ messages in thread
* [PATCH v2 3/3] migration: stop returning errno from load_snapshot()
  2020-10-12 12:27 [PATCH v2 0/3] migration: Make save/load_snapshot() return boolean Philippe Mathieu-Daudé
  2020-10-12 12:27 ` [PATCH v2 1/3] block: push error reporting into bdrv_all_*_snapshot functions Philippe Mathieu-Daudé
  2020-10-12 12:27 ` [PATCH v2 2/3] migration: Make save_snapshot() return bool, not 0/-1 Philippe Mathieu-Daudé
@ 2020-10-12 12:27 ` Philippe Mathieu-Daudé
  2020-10-21 10:12   ` Daniel P. Berrangé
  2 siblings, 1 reply; 8+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-10-12 12:27 UTC (permalink / raw)
  To: qemu-devel
  Cc: Kevin Wolf, Daniel P . Berrangé,
	qemu-block, Juan Quintela, Dr. David Alan Gilbert, Max Reitz,
	Pavel Dovgalyuk, Pavel Dovgalyuk, Paolo Bonzini,
	Philippe Mathieu-Daudé

From: Daniel P. Berrangé <berrange@redhat.com>

None of the callers care about the errno value since there is a full
Error object populated. This gives consistency with save_snapshot()
which already just returns a boolean value.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[PMD: Return false/true instead of -1/0, document function]
Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/migration/snapshot.h |  9 ++++++++-
 migration/savevm.c           | 19 +++++++++----------
 monitor/hmp-cmds.c           |  2 +-
 replay/replay-snapshot.c     |  2 +-
 softmmu/vl.c                 |  2 +-
 5 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
index a40c34307b5..9bc989a6b49 100644
--- a/include/migration/snapshot.h
+++ b/include/migration/snapshot.h
@@ -23,6 +23,13 @@
  * On failure, store an error through @errp and return %false.
  */
 bool save_snapshot(const char *name, Error **errp);
-int load_snapshot(const char *name, Error **errp);
+/**
+ * save_snapshot: Load a snapshot.
+ * @name: path to snapshot
+ * @errp: pointer to error object
+ * On success, return %true.
+ * On failure, store an error through @errp and return %false.
+ */
+bool load_snapshot(const char *name, Error **errp);
 
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index fd2e5e8b663..531bb2eca1e 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2864,7 +2864,7 @@ void qmp_xen_load_devices_state(const char *filename, Error **errp)
     migration_incoming_state_destroy();
 }
 
-int load_snapshot(const char *name, Error **errp)
+bool load_snapshot(const char *name, Error **errp)
 {
     BlockDriverState *bs_vm_state;
     QEMUSnapshotInfo sn;
@@ -2874,16 +2874,16 @@ int load_snapshot(const char *name, Error **errp)
     MigrationIncomingState *mis = migration_incoming_get_current();
 
     if (!bdrv_all_can_snapshot(errp)) {
-        return -ENOTSUP;
+        return false;
     }
     ret = bdrv_all_find_snapshot(name, errp);
     if (ret < 0) {
-        return ret;
+        return false;
     }
 
     bs_vm_state = bdrv_all_find_vmstate_bs(errp);
     if (!bs_vm_state) {
-        return -ENOTSUP;
+        return false;
     }
     aio_context = bdrv_get_aio_context(bs_vm_state);
 
@@ -2892,11 +2892,11 @@ int load_snapshot(const char *name, Error **errp)
     ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
     aio_context_release(aio_context);
     if (ret < 0) {
-        return ret;
+        return false;
     } else if (sn.vm_state_size == 0) {
         error_setg(errp, "This is a disk-only snapshot. Revert to it "
                    " offline using qemu-img");
-        return -EINVAL;
+        return false;
     }
 
     /*
@@ -2917,7 +2917,6 @@ int load_snapshot(const char *name, Error **errp)
     f = qemu_fopen_bdrv(bs_vm_state, 0);
     if (!f) {
         error_setg(errp, "Could not open VM state file");
-        ret = -EINVAL;
         goto err_drain;
     }
 
@@ -2933,14 +2932,14 @@ int load_snapshot(const char *name, Error **errp)
 
     if (ret < 0) {
         error_setg(errp, "Error %d while loading VM state", ret);
-        return ret;
+        return false;
     }
 
-    return 0;
+    return true;
 
 err_drain:
     bdrv_drain_all_end();
-    return ret;
+    return false;
 }
 
 void vmstate_register_ram(MemoryRegion *mr, DeviceState *dev)
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index f48173820ff..521fcf96eba 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -1123,7 +1123,7 @@ void hmp_loadvm(Monitor *mon, const QDict *qdict)
 
     vm_stop(RUN_STATE_RESTORE_VM);
 
-    if (load_snapshot(name, &err) == 0 && saved_vm_running) {
+    if (!load_snapshot(name, &err) && saved_vm_running) {
         vm_start();
     }
     hmp_handle_error(mon, err);
diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
index 4f2560d1568..b2893659370 100644
--- a/replay/replay-snapshot.c
+++ b/replay/replay-snapshot.c
@@ -83,7 +83,7 @@ void replay_vmstate_init(void)
                 exit(1);
             }
         } else if (replay_mode == REPLAY_MODE_PLAY) {
-            if (load_snapshot(replay_snapshot, &err) != 0) {
+            if (!load_snapshot(replay_snapshot, &err)) {
                 error_report_err(err);
                 error_report("Could not load snapshot for icount replay");
                 exit(1);
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 5a11a62f78a..6eaa6b3a09a 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -4478,7 +4478,7 @@ void qemu_init(int argc, char **argv, char **envp)
     register_global_state();
     if (loadvm) {
         Error *local_err = NULL;
-        if (load_snapshot(loadvm, &local_err) < 0) {
+        if (!load_snapshot(loadvm, &local_err)) {
             error_report_err(local_err);
             autostart = 0;
             exit(1);
-- 
2.26.2



^ permalink raw reply related	[flat|nested] 8+ messages in thread
* Re: [PATCH v2 1/3] block: push error reporting into bdrv_all_*_snapshot functions
  2020-10-12 12:27 ` [PATCH v2 1/3] block: push error reporting into bdrv_all_*_snapshot functions Philippe Mathieu-Daudé
@ 2020-10-12 15:21   ` Max Reitz
  0 siblings, 0 replies; 8+ messages in thread
From: Max Reitz @ 2020-10-12 15:21 UTC (permalink / raw)
  To: Philippe Mathieu-Daudé, qemu-devel
  Cc: Kevin Wolf, Daniel P . Berrangé,
	qemu-block, Juan Quintela, Dr. David Alan Gilbert,
	Pavel Dovgalyuk, Paolo Bonzini

On 12.10.20 14:27, Philippe Mathieu-Daudé wrote:
> From: Daniel P. Berrangé <berrange@redhat.com>
> 
> The bdrv_all_*_snapshot functions return a BlockDriverState pointer
> for the invalid backend, which the callers then use to report an
> error message. In some cases multiple callers are reporting the
> same error message, but with slightly different text. In the future
> there will be more error scenarios for some of these methods, which
> will benefit from fine grained error message reporting. So it is
> helpful to push error reporting down a level.
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> [PMD: Initialize variables]
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  include/block/snapshot.h       | 14 +++----
>  block/monitor/block-hmp-cmds.c |  7 ++--
>  block/snapshot.c               | 77 +++++++++++++++++-----------------
>  migration/savevm.c             | 37 +++++-----------
>  monitor/hmp-cmds.c             |  7 +---
>  replay/replay-debugging.c      |  4 +-
>  tests/qemu-iotests/267.out     | 10 ++---
>  7 files changed, 67 insertions(+), 89 deletions(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>



^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH v2 2/3] migration: Make save_snapshot() return bool, not 0/-1
  2020-10-12 12:27 ` [PATCH v2 2/3] migration: Make save_snapshot() return bool, not 0/-1 Philippe Mathieu-Daudé
@ 2020-10-21  9:56   ` Daniel P. Berrangé
  2020-10-21 10:04     ` Philippe Mathieu-Daudé
  0 siblings, 1 reply; 8+ messages in thread
From: Daniel P. Berrangé @ 2020-10-21  9:56 UTC (permalink / raw)
  To: Philippe Mathieu-Daudé
  Cc: Kevin Wolf, Pavel Dovgalyuk, qemu-block, Juan Quintela,
	qemu-devel, Max Reitz, Pavel Dovgalyuk, Paolo Bonzini,
	Dr. David Alan Gilbert

On Mon, Oct 12, 2020 at 02:27:42PM +0200, Philippe Mathieu-Daudé wrote:
> Just for consistency, following the example documented since
> commit e3fe3988d7 ("error: Document Error API usage rules"),
> return a boolean value indicating an error is set or not.
> 
> Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  include/migration/snapshot.h |  9 ++++++++-
>  migration/savevm.c           | 16 ++++++++--------
>  replay/replay-debugging.c    |  2 +-
>  replay/replay-snapshot.c     |  2 +-
>  4 files changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
> index c85b6ec75b7..a40c34307b5 100644
> --- a/include/migration/snapshot.h
> +++ b/include/migration/snapshot.h
> @@ -15,7 +15,14 @@
>  #ifndef QEMU_MIGRATION_SNAPSHOT_H
>  #define QEMU_MIGRATION_SNAPSHOT_H
>  
> -int save_snapshot(const char *name, Error **errp);
> +/**
> + * save_snapshot: Save a snapshot.
> + * @name: path to snapshot

This isn't a path, it is a name.

I'll apply this change:

  - * save_snapshot: Save a snapshot.
  - * @name: path to snapshot
  + * save_snapshot: Save an internal snapshot.
  + * @name: name of internal snapshot



Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|



^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH v2 2/3] migration: Make save_snapshot() return bool, not 0/-1
  2020-10-21  9:56   ` Daniel P. Berrangé
@ 2020-10-21 10:04     ` Philippe Mathieu-Daudé
  0 siblings, 0 replies; 8+ messages in thread
From: Philippe Mathieu-Daudé @ 2020-10-21 10:04 UTC (permalink / raw)
  To: Daniel P. Berrangé
  Cc: Kevin Wolf, Pavel Dovgalyuk, qemu-block, Juan Quintela,
	qemu-devel, Max Reitz, Pavel Dovgalyuk, Paolo Bonzini,
	Dr. David Alan Gilbert

On 10/21/20 11:56 AM, Daniel P. Berrangé wrote:
> On Mon, Oct 12, 2020 at 02:27:42PM +0200, Philippe Mathieu-Daudé wrote:
>> Just for consistency, following the example documented since
>> commit e3fe3988d7 ("error: Document Error API usage rules"),
>> return a boolean value indicating an error is set or not.
>>
>> Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> ---
>>   include/migration/snapshot.h |  9 ++++++++-
>>   migration/savevm.c           | 16 ++++++++--------
>>   replay/replay-debugging.c    |  2 +-
>>   replay/replay-snapshot.c     |  2 +-
>>   4 files changed, 18 insertions(+), 11 deletions(-)
>>
>> diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
>> index c85b6ec75b7..a40c34307b5 100644
>> --- a/include/migration/snapshot.h
>> +++ b/include/migration/snapshot.h
>> @@ -15,7 +15,14 @@
>>   #ifndef QEMU_MIGRATION_SNAPSHOT_H
>>   #define QEMU_MIGRATION_SNAPSHOT_H
>>   
>> -int save_snapshot(const char *name, Error **errp);
>> +/**
>> + * save_snapshot: Save a snapshot.
>> + * @name: path to snapshot
> 
> This isn't a path, it is a name.
> 
> I'll apply this change:
> 
>    - * save_snapshot: Save a snapshot.
>    - * @name: path to snapshot
>    + * save_snapshot: Save an internal snapshot.
>    + * @name: name of internal snapshot

Thanks!



^ permalink raw reply	[flat|nested] 8+ messages in thread
* Re: [PATCH v2 3/3] migration: stop returning errno from load_snapshot()
  2020-10-12 12:27 ` [PATCH v2 3/3] migration: stop returning errno from load_snapshot() Philippe Mathieu-Daudé
@ 2020-10-21 10:12   ` Daniel P. Berrangé
  0 siblings, 0 replies; 8+ messages in thread
From: Daniel P. Berrangé @ 2020-10-21 10:12 UTC (permalink / raw)
  To: Philippe Mathieu-Daudé
  Cc: Kevin Wolf, Pavel Dovgalyuk, qemu-block, Juan Quintela,
	qemu-devel, Max Reitz, Pavel Dovgalyuk, Paolo Bonzini,
	Dr. David Alan Gilbert

On Mon, Oct 12, 2020 at 02:27:43PM +0200, Philippe Mathieu-Daudé wrote:
> From: Daniel P. Berrangé <berrange@redhat.com>
> 
> None of the callers care about the errno value since there is a full
> Error object populated. This gives consistency with save_snapshot()
> which already just returns a boolean value.
> 
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> [PMD: Return false/true instead of -1/0, document function]
> Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  include/migration/snapshot.h |  9 ++++++++-
>  migration/savevm.c           | 19 +++++++++----------
>  monitor/hmp-cmds.c           |  2 +-
>  replay/replay-snapshot.c     |  2 +-
>  softmmu/vl.c                 |  2 +-
>  5 files changed, 20 insertions(+), 14 deletions(-)
> 
> diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
> index a40c34307b5..9bc989a6b49 100644
> --- a/include/migration/snapshot.h
> +++ b/include/migration/snapshot.h
> @@ -23,6 +23,13 @@
>   * On failure, store an error through @errp and return %false.
>   */
>  bool save_snapshot(const char *name, Error **errp);
> -int load_snapshot(const char *name, Error **errp);
> +/**
> + * save_snapshot: Load a snapshot.

s/save/load/

> + * @name: path to snapshot

Again, a name not a path. I'll apply this

- * save_snapshot: Load a snapshot.
- * @name: path to snapshot
+ * load_snapshot: Load an internal snapshot.
+ * @name: name of internal snapshot



Regards,
Daniel
-- 
|: https://berrange.com      -o-    https://www.flickr.com/photos/dberrange :|
|: https://libvirt.org         -o-            https://fstop138.berrange.com :|
|: https://entangle-photo.org    -o-    https://www.instagram.com/dberrange :|



^ permalink raw reply	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2020-10-21 10:13 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-12 12:27 [PATCH v2 0/3] migration: Make save/load_snapshot() return boolean Philippe Mathieu-Daudé
2020-10-12 12:27 ` [PATCH v2 1/3] block: push error reporting into bdrv_all_*_snapshot functions Philippe Mathieu-Daudé
2020-10-12 15:21   ` Max Reitz
2020-10-12 12:27 ` [PATCH v2 2/3] migration: Make save_snapshot() return bool, not 0/-1 Philippe Mathieu-Daudé
2020-10-21  9:56   ` Daniel P. Berrangé
2020-10-21 10:04     ` Philippe Mathieu-Daudé
2020-10-12 12:27 ` [PATCH v2 3/3] migration: stop returning errno from load_snapshot() Philippe Mathieu-Daudé
2020-10-21 10:12   ` Daniel P. Berrangé

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