[Qemu-devel] [PATCH v2 3/3] block: use proper qerrors in qmp_block_resize

[Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>]

Let's report specific errors so that management tools and users can
identify the problem.

Two new qerrors are needed:
 * QERR_DEVICE_HAS_NO_MEDIUM for ENOMEDIUM
 * QERR_DEVICE_IS_READ_ONLY for EACCES

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 blockdev.c       |   26 ++++++++++++++++++--------
 qapi-schema.json |    7 +++++--
 qerror.c         |    8 ++++++++
 qerror.h         |    6 ++++++
 4 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index c832782..8c2c8cc 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -841,11 +841,6 @@ int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
     return 0;
 }
 
-/*
- * XXX: replace the QERR_UNDEFINED_ERROR errors with real values once the
- * existing QERR_ macro mess is cleaned up.  A good example for better
- * error reports can be found in the qemu-img resize code.
- */
 void qmp_block_resize(const char *device, int64_t size, Error **errp)
 {
     BlockDriverState *bs;
@@ -857,12 +852,27 @@ void qmp_block_resize(const char *device, int64_t size, Error **errp)
     }
 
     if (size < 0) {
-        error_set(errp, QERR_UNDEFINED_ERROR);
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "size", "a >0 size");
         return;
     }
 
-    if (bdrv_truncate(bs, size)) {
+    switch (bdrv_truncate(bs, size)) {
+    case 0:
+        break;
+    case -ENOMEDIUM:
+        error_set(errp, QERR_DEVICE_HAS_NO_MEDIUM, device);
+        break;
+    case -ENOTSUP:
+        error_set(errp, QERR_UNSUPPORTED);
+        break;
+    case -EACCES:
+        error_set(errp, QERR_DEVICE_IS_READ_ONLY, device);
+        break;
+    case -EBUSY:
+        error_set(errp, QERR_DEVICE_IN_USE, device);
+        break;
+    default:
         error_set(errp, QERR_UNDEFINED_ERROR);
-        return;
+        break;
     }
 }
diff --git a/qapi-schema.json b/qapi-schema.json
index 44cf764..a8b1232 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1064,8 +1064,11 @@
 #
 # Returns: nothing on success
 #          If @device is not a valid block device, DeviceNotFound
-#
-# Notes: This command returns UndefinedError in a number of error conditions.
+#          If @size is negative, InvalidParameterValue
+#          If the block device has no medium inserted, DeviceHasNoMedium
+#          If the block device does not support resize, Unsupported
+#          If the block device is read-only, DeviceIsReadOnly
+#          If a long-running operation is using the device, DeviceInUse
 #
 # Since: 0.14.0
 ##
diff --git a/qerror.c b/qerror.c
index 2979b3e..3d95383 100644
--- a/qerror.c
+++ b/qerror.c
@@ -80,6 +80,10 @@ static const QErrorStringTable qerror_table[] = {
         .desc      = "Migration is disabled when using feature '%(feature)' in device '%(device)'",
     },
     {
+        .error_fmt = QERR_DEVICE_HAS_NO_MEDIUM,
+        .desc      = "Device '%(device)' has no medium",
+    },
+    {
         .error_fmt = QERR_DEVICE_INIT_FAILED,
         .desc      = "Device '%(device)' could not be initialized",
     },
@@ -88,6 +92,10 @@ static const QErrorStringTable qerror_table[] = {
         .desc      = "Device '%(device)' is in use",
     },
     {
+        .error_fmt = QERR_DEVICE_IS_READ_ONLY,
+        .desc      = "Device '%(device)' is read only",
+    },
+    {
         .error_fmt = QERR_DEVICE_LOCKED,
         .desc      = "Device '%(device)' is locked",
     },
diff --git a/qerror.h b/qerror.h
index c34674e..947dadc 100644
--- a/qerror.h
+++ b/qerror.h
@@ -81,12 +81,18 @@ QError *qobject_to_qerror(const QObject *obj);
 #define QERR_DEVICE_FEATURE_BLOCKS_MIGRATION \
     "{ 'class': 'DeviceFeatureBlocksMigration', 'data': { 'device': %s, 'feature': %s } }"
 
+#define QERR_DEVICE_HAS_NO_MEDIUM \
+    "{ 'class': 'DeviceHasNoMedium', 'data': { 'device': %s } }"
+
 #define QERR_DEVICE_INIT_FAILED \
     "{ 'class': 'DeviceInitFailed', 'data': { 'device': %s } }"
 
 #define QERR_DEVICE_IN_USE \
     "{ 'class': 'DeviceInUse', 'data': { 'device': %s } }"
 
+#define QERR_DEVICE_IS_READ_ONLY \
+    "{ 'class': 'DeviceIsReadOnly', 'data': { 'device': %s } }"
+
 #define QERR_DEVICE_LOCKED \
     "{ 'class': 'DeviceLocked', 'data': { 'device': %s } }"
 
-- 
1.7.7.3