[libvirt] [PATCH] qemu: Limit maximum block device I/O tune values

[Martin Kletzander]

The values are currently limited to LLONG_MAX which causes some
problems.  QEMU conveniently changed their maximum to 1e15 (1 PB) which
is enough for some time and we need to adapt to that so that we don't
throw "Unknown error" messages.  Strictly limiting these values actually
fixes some corner case values (off-by-one checks in QEMU probably).

Since values out of the new specified range do not overflow anything,
change the type of error as well.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1317531

Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
---
 src/qemu/qemu_command.c | 30 +++++++++++++++---------------
 src/qemu/qemu_command.h |  2 ++
 src/qemu/qemu_driver.c  |  6 +++---
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 2fb967acbfe8..ef4a62dafb5b 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1394,22 +1394,22 @@ qemuBuildDriveStr(virConnectPtr conn,
         goto error;
     }

-    if (disk->blkdeviotune.total_bytes_sec > LLONG_MAX ||
-        disk->blkdeviotune.read_bytes_sec > LLONG_MAX ||
-        disk->blkdeviotune.write_bytes_sec > LLONG_MAX ||
-        disk->blkdeviotune.total_iops_sec > LLONG_MAX ||
-        disk->blkdeviotune.read_iops_sec > LLONG_MAX ||
-        disk->blkdeviotune.write_iops_sec > LLONG_MAX ||
-        disk->blkdeviotune.total_bytes_sec_max > LLONG_MAX ||
-        disk->blkdeviotune.read_bytes_sec_max > LLONG_MAX ||
-        disk->blkdeviotune.write_bytes_sec_max > LLONG_MAX ||
-        disk->blkdeviotune.total_iops_sec_max > LLONG_MAX ||
-        disk->blkdeviotune.read_iops_sec_max > LLONG_MAX ||
-        disk->blkdeviotune.write_iops_sec_max > LLONG_MAX ||
-        disk->blkdeviotune.size_iops_sec > LLONG_MAX) {
-        virReportError(VIR_ERR_OVERFLOW,
+    if (disk->blkdeviotune.total_bytes_sec > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.read_bytes_sec > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.write_bytes_sec > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.total_iops_sec > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.read_iops_sec > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.write_iops_sec > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.total_bytes_sec_max > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.read_bytes_sec_max > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.write_bytes_sec_max > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.total_iops_sec_max > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.read_iops_sec_max > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.write_iops_sec_max > QEMU_BLOCK_IOTUNE_MAX ||
+        disk->blkdeviotune.size_iops_sec > QEMU_BLOCK_IOTUNE_MAX) {
+        virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED,
                       _("block I/O throttle limit must "
-                        "be less than %llu using QEMU"), LLONG_MAX);
+                        "be less than %llu using QEMU"), QEMU_BLOCK_IOTUNE_MAX);
         goto error;
     }

diff --git a/src/qemu/qemu_command.h b/src/qemu/qemu_command.h
index 2e2f133ac341..1e9ce6690603 100644
--- a/src/qemu/qemu_command.h
+++ b/src/qemu/qemu_command.h
@@ -40,6 +40,8 @@
 # define QEMU_DRIVE_HOST_PREFIX "drive-"
 # define QEMU_FSDEV_HOST_PREFIX "fsdev-"

+# define QEMU_BLOCK_IOTUNE_MAX 1000000000000000LL
+
 VIR_ENUM_DECL(qemuVideo)

 char *qemuBuildObjectCommandlineFromJSON(const char *type,
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 055f0714ddf3..90f541cf6d74 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -17526,10 +17526,10 @@ qemuDomainSetBlockIoTune(virDomainPtr dom,
     for (i = 0; i < nparams; i++) {
         virTypedParameterPtr param = &params[i];

-        if (param->value.ul > LLONG_MAX) {
-            virReportError(VIR_ERR_OVERFLOW,
+        if (param->value.ul > QEMU_BLOCK_IOTUNE_MAX) {
+            virReportError(VIR_ERR_ARGUMENT_UNSUPPORTED,
                            _("block I/O throttle limit value must"
-                             " be less than %llu"), LLONG_MAX);
+                             " be less than %llu"), QEMU_BLOCK_IOTUNE_MAX);
             goto endjob;
         }

-- 
2.8.1