Re: [Qemu-devel] [v1 Patch 3/10]Qemu: Cmd "block_set_hostcache" for dynamic cache change

[Shrinidhi Joshi]

On Wednesday 20 June 2012 11:48 PM, Jeff Cody wrote:
> On 06/15/2012 04:47 PM, Supriya Kannery wrote:
>> New command "block_set_hostcache" added for dynamically changing
>> host pagecache setting of a block device.
>>
>> Usage:
>> block_set_hostcache <device> <option>
>> <device> = block device
>> <option> = on/off
>>
>> Example:
>> (qemu) block_set_hostcache ide0-hd0 off
>>
>> Signed-off-by: Supriya Kannery <address@hidden>
>>
>> ---
>> block.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> block.h | 2 ++
>> blockdev.c | 26 ++++++++++++++++++++++++++
>> blockdev.h | 2 ++
>> hmp-commands.hx | 14 ++++++++++++++
>> qmp-commands.hx | 27 +++++++++++++++++++++++++++
>> 6 files changed, 125 insertions(+)
>>
>> Index: qemu/block.c
>> ===================================================================
>> --- qemu.orig/block.c
>> +++ qemu/block.c
>> @@ -858,6 +858,35 @@ unlink_and_fail:
>> return ret;
>> }
>>
>> +int bdrv_reopen(BlockDriverState *bs, int bdrv_flags)
>> +{
>> + BlockDriver *drv = bs->drv;
>> + int ret = 0, open_flags;
>> +
>> + /* Quiesce IO for the given block device */
>> + qemu_aio_flush();
>> + ret = bdrv_flush(bs);
>> + if (ret != 0) {
>> + qerror_report(QERR_DATA_SYNC_FAILED, bs->device_name);
>> + return ret;
>> + }
>> + open_flags = bs->open_flags;
>> + bdrv_close(bs);
>> +
>> + ret = bdrv_open(bs, bs->filename, bdrv_flags, drv);
>> + if (ret < 0) {
>> + /* Reopen failed. Try to open with original flags */
>> + qerror_report(QERR_OPEN_FILE_FAILED, bs->filename);
>> + ret = bdrv_open(bs, bs->filename, open_flags, drv);
>> + if (ret < 0) {
>> + /* Reopen failed with orig and modified flags */
>> + abort();
>> + }
>> + }
>> +
>> + return ret;
>> +}
>> +
>> void bdrv_close(BlockDriverState *bs)
>> {
>> bdrv_flush(bs);
>> @@ -953,6 +982,34 @@ void bdrv_drain_all(void)
>> }
>> }
>>
>> +int bdrv_change_hostcache(BlockDriverState *bs, bool enable)
>> +{
>> + int bdrv_flags = bs->open_flags;
>> +
>> + /* set hostcache flags (without changing WCE/flush bits) */
>> + if (enable) {
>> + bdrv_flags &= ~BDRV_O_NOCACHE;
>> + } else {
>> + bdrv_flags |= BDRV_O_NOCACHE;
>> + }
>> +
>> + /* If no change in flags, no need to reopen */
>> + if (bdrv_flags == bs->open_flags) {
>> + printf("no need to change\n");
>> + return 0;
>> + }
>> +
>> + if (bdrv_is_inserted(bs)) {
>> + /* Reopen file with changed set of flags */
>> + bdrv_flags &= ~BDRV_O_CACHE_WB;
>> + return bdrv_reopen(bs, bdrv_flags);
>> + } else {
>> + /* Save hostcache change for future use */
>> + bs->open_flags = bdrv_flags;
>> + return 0;
>> + }
>> +}
>> +
>> /* make a BlockDriverState anonymous by removing from bdrv_state list.
>> Also, NULL terminate the device_name to prevent double remove */
>> void bdrv_make_anon(BlockDriverState *bs)
>> Index: qemu/block.h
>> ===================================================================
>> --- qemu.orig/block.h
>> +++ qemu/block.h
>> @@ -128,6 +128,7 @@ int bdrv_parse_cache_flags(const char *m
>> int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags);
>> int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
>> BlockDriver *drv);
>> +int bdrv_reopen(BlockDriverState *bs, int bdrv_flags);
>> void bdrv_close(BlockDriverState *bs);
>> int bdrv_attach_dev(BlockDriverState *bs, void *dev);
>> void bdrv_attach_dev_nofail(BlockDriverState *bs, void *dev);
>> @@ -177,6 +178,7 @@ int bdrv_commit_all(void);
>> int bdrv_change_backing_file(BlockDriverState *bs,
>> const char *backing_file, const char *backing_fmt);
>> void bdrv_register(BlockDriver *bdrv);
>> +int bdrv_change_hostcache(BlockDriverState *bs, bool enable_host_cache);
>>
>>
>> typedef struct BdrvCheckResult {
>> Index: qemu/blockdev.c
>> ===================================================================
>> --- qemu.orig/blockdev.c
>> +++ qemu/blockdev.c
>> @@ -1198,3 +1198,27 @@ BlockJobInfoList *qmp_query_block_jobs(E
>> bdrv_iterate(do_qmp_query_block_jobs_one, &prev);
>> return dummy.next;
>> }
>> +
>> +
>> +/*
>> + * Change host page cache setting while guest is running.
>> +*/
>> +void qmp_block_set_hostcache(const char *device, bool enable,
>> + Error **errp)
>> +{
>> + BlockDriverState *bs = NULL;
>> +
>> + /* Validate device */
>> + bs = bdrv_find(device);
>> + if (!bs) {
>> + error_set(errp, QERR_DEVICE_NOT_FOUND, device);
>> + return;
>> + }
>> +
>> + if (bdrv_change_hostcache(bs, enable)) {
>> + error_set(errp, QERR_HOSTCACHE_NOT_CHANGED, device);
>> + }
>> +
>> + return;
>> +}
>> +
>> Index: qemu/hmp-commands.hx
>> ===================================================================
>> --- qemu.orig/hmp-commands.hx
>> +++ qemu/hmp-commands.hx
>> @@ -808,7 +808,6 @@ ETEXI
>> .mhandler.cmd = hmp_migrate,
>> },
>>
>> -
>> STEXI
>> @item migrate [-d] [-b] [-i] @var{uri}
>> @findex migrate
>> @@ -1314,6 +1313,21 @@ client. @var{keep} changes the password
>> ETEXI
>>
>> {
>> + .name = "block_set_hostcache",
>> + .args_type = "device:B,option:b",
>> + .params = "device on|off",
>> + .help = "Change setting of host pagecache",
>> + .mhandler.cmd = hmp_block_set_hostcache,
>> + },
>> +
>> +STEXI
>> address@hidden block_set_hostcache @var{device} @var{option}
>> address@hidden block_set_hostcache
>> +Change host pagecache setting of a block device while guest is running.
>> +ETEXI
>> +
>> +
>> + {
>> .name = "expire_password",
>> .args_type = "protocol:s,time:s",
>> .params = "protocol time",
>> Index: qemu/qmp-commands.hx
>> ===================================================================
>> --- qemu.orig/qmp-commands.hx
>> +++ qemu/qmp-commands.hx
>> @@ -821,7 +821,31 @@ Example:
>>
>> EQMP
>>
>> +
>> {
>> + .name = "block_set_hostcache",
>> + .args_type = "device:B,option:b",
>> + .mhandler.cmd_new = qmp_block_set_hostcache,
>
> The QAPI commands need to go through the marshaller - this needs to be:
> .mhandler.cmd_new = qmp_marshal_input_block_set_hostcache,
>
> (qmp_marshal_input_block_set_hostcache is automatically generated, and
> it will call qmp_block_set_hostcache)
>
>> + },
>> +
>> +SQMP
>> +block_set_hostcache
>> +-------------------
>> +
>> +Change host pagecache setting of a block device
>> +
>> +Arguments:
>> +
>> +- "device": the device's ID, must be unique (json-string)
>> +- "option": hostcache setting (json-bool)
>> +
>> +Example:
>> +-> { "execute": "block_set_hostcache", "arguments": { "device": "ide0-hd0", "option": false } }
>> +<- { "return": {} }
>> +
>> +EQMP
>> +
>> + {
>> .name = "balloon",
>> .args_type = "value:M",
>> .mhandler.cmd_new = qmp_marshal_input_balloon,
>> Index: qemu/qapi-schema.json
>> ===================================================================
>> --- qemu.orig/qapi-schema.json
>> +++ qemu/qapi-schema.json
>> @@ -1598,6 +1598,22 @@
>> { 'command': 'block_set_io_throttle',
>> 'data': { 'device': 'str', 'bps': 'int', 'bps_rd': 'int', 'bps_wr': 'int',
>> 'iops': 'int', 'iops_rd': 'int', 'iops_wr': 'int' } }
>> +##
>> +# @block_set_hostcache:
>> +#
>> +# Change host pagecache setting of a block device
>> +#
>> +# @device: name of the block device
>> +#
>> +# @option: hostcache setting (true/false)
>> +#
>> +# Returns: Nothing on success
>> +# If @device is not a valid block device, DeviceNotFound
>> +#
>> +# Since: 1.2
>> +##
>> +{ 'command': 'block_set_hostcache',
>> + 'data': { 'device': 'str', 'option': 'bool' } }
>>
>> ##
>> # @block-stream:
>> Index: qemu/hmp.c
>> ===================================================================
>> --- qemu.orig/hmp.c
>> +++ qemu/hmp.c
>> @@ -836,6 +836,15 @@ void hmp_block_set_io_throttle(Monitor *
>> hmp_handle_error(mon, &err);
>> }
>>
>> +void hmp_block_set_hostcache(Monitor *mon, const QDict *qdict)
>> +{
>> + Error *err = NULL;
>> +
>> + qmp_block_set_hostcache(qdict_get_str(qdict, "device"),
>> + qdict_get_bool(qdict, "option"), &err);
>> + hmp_handle_error(mon, &err);
>> +}
>> +
>> void hmp_block_stream(Monitor *mon, const QDict *qdict)
>> {
>> Error *error = NULL;
>> Index: qemu/hmp.h
>> ===================================================================
>> --- qemu.orig/hmp.h
>> +++ qemu/hmp.h
>> @@ -64,5 +64,6 @@ void hmp_device_del(Monitor *mon, const
>> void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict);
>> void hmp_netdev_add(Monitor *mon, const QDict *qdict);
>> void hmp_netdev_del(Monitor *mon, const QDict *qdict);
>> +void hmp_block_set_hostcache(Monitor *mon, const QDict *qdict);
>>
>> #endif
>>
>>
>
Updated patch to auto generate qmp_marshal_input_block_set_hostcache

--------------------------------------------------------------------
New command "block_set_hostcache" added for dynamically changing
host pagecache setting of a block device.

Usage:
 block_set_hostcache  <device> <option>
   <device> = block device
   <option> = on/off

Example:
 (qemu) block_set_hostcache ide0-hd0 off

Signed-off-by: Supriya Kannery <address@hidden>

Signed-off-by: Shrinidhi Joshi <address@hidden>
---
 block.c         |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 block.h         |    2 ++
 blockdev.c      |   26 ++++++++++++++++++++++++++
 blockdev.h      |    2 ++
 hmp-commands.hx |   14 ++++++++++++++
 qmp-commands.hx |   27 +++++++++++++++++++++++++++
 6 files changed, 125 insertions(+)

Index: qemu/block.c
===================================================================
--- qemu.orig/block.c    2012-06-19 17:24:34.335927717 +0530
+++ qemu/block.c    2012-06-25 09:18:06.940040103 +0530
@@ -859,6 +859,35 @@
     return ret;
 }
 
+int bdrv_reopen(BlockDriverState *bs, int bdrv_flags)
+{
+    BlockDriver *drv = bs->drv;
+    int ret = 0, open_flags;
+
+    /* Quiesce IO for the given block device */
+    qemu_aio_flush();
+    ret = bdrv_flush(bs);
+    if (ret != 0) {
+        qerror_report(QERR_DATA_SYNC_FAILED, bs->device_name);
+        return ret;
+    }
+    open_flags = bs->open_flags;
+    bdrv_close(bs);
+
+    ret = bdrv_open(bs, bs->filename, bdrv_flags, drv);
+    if (ret < 0) {
+        /* Reopen failed. Try to open with original flags */
+        qerror_report(QERR_OPEN_FILE_FAILED, bs->filename);
+        ret = bdrv_open(bs, bs->filename, open_flags, drv);
+        if (ret < 0) {
+            /* Reopen failed with orig and modified flags */
+            abort();
+        }
+    }
+
+    return ret;
+}
+
 void bdrv_close(BlockDriverState *bs)
 {
     bdrv_flush(bs);
@@ -954,6 +983,34 @@
     }
 }
 
+int bdrv_change_hostcache(BlockDriverState *bs, bool enable)
+{
+    int bdrv_flags = bs->open_flags;
+
+    /* set hostcache flags (without changing WCE/flush bits) */
+    if (enable) {
+        bdrv_flags &= ~BDRV_O_NOCACHE;
+    } else {
+        bdrv_flags |= BDRV_O_NOCACHE;
+    }
+
+    /* If no change in flags, no need to reopen */
+    if (bdrv_flags == bs->open_flags) {
+        printf("no need to change\n");
+        return 0;
+    }
+
+    if (bdrv_is_inserted(bs)) {
+        /* Reopen file with changed set of flags */
+        bdrv_flags &= ~BDRV_O_CACHE_WB;
+        return bdrv_reopen(bs, bdrv_flags);
+    } else {
+        /* Save hostcache change for future use */
+        bs->open_flags = bdrv_flags;
+        return 0;
+    }
+}
+
 /* make a BlockDriverState anonymous by removing from bdrv_state list.
    Also, NULL terminate the device_name to prevent double remove */
 void bdrv_make_anon(BlockDriverState *bs)
Index: qemu/block.h
===================================================================
--- qemu.orig/block.h    2012-06-19 15:52:43.516601040 +0530
+++ qemu/block.h    2012-06-25 09:18:06.912039970 +0530
@@ -128,6 +128,7 @@
 int bdrv_file_open(BlockDriverState **pbs, const char *filename, int flags);
 int bdrv_open(BlockDriverState *bs, const char *filename, int flags,
               BlockDriver *drv);
+int bdrv_reopen(BlockDriverState *bs, int bdrv_flags);
 void bdrv_close(BlockDriverState *bs);
 int bdrv_attach_dev(BlockDriverState *bs, void *dev);
 void bdrv_attach_dev_nofail(BlockDriverState *bs, void *dev);
@@ -181,6 +182,7 @@
 int bdrv_change_backing_file(BlockDriverState *bs,
     const char *backing_file, const char *backing_fmt);
 void bdrv_register(BlockDriver *bdrv);
+int bdrv_change_hostcache(BlockDriverState *bs, bool enable_host_cache);
 
 
 typedef struct BdrvCheckResult {
Index: qemu/blockdev.c
===================================================================
--- qemu.orig/blockdev.c    2012-06-19 15:52:43.532601120 +0530
+++ qemu/blockdev.c    2012-06-19 17:24:54.124025837 +0530
@@ -1195,3 +1195,27 @@
     bdrv_iterate(do_qmp_query_block_jobs_one, &prev);
     return dummy.next;
 }
+
+
+/*
+ * Change host page cache setting while guest is running.
+*/
+void qmp_block_set_hostcache(const char *device, bool enable,
+                             Error **errp)
+{
+    BlockDriverState *bs = NULL;
+
+    /* Validate device */
+    bs = bdrv_find(device);
+    if (!bs) {
+        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+        return;
+    }
+
+    if (bdrv_change_hostcache(bs, enable)) {
+        error_set(errp, QERR_HOSTCACHE_NOT_CHANGED, device);
+    }
+
+    return;
+}
+
Index: qemu/hmp-commands.hx
===================================================================
--- qemu.orig/hmp-commands.hx    2012-06-19 15:52:43.536601135 +0530
+++ qemu/hmp-commands.hx    2012-06-19 17:24:54.124025837 +0530
@@ -808,7 +808,6 @@
         .mhandler.cmd = hmp_migrate,
     },
 
-
 STEXI
 @item migrate [-d] [-b] [-i] @var{uri}
 @findex migrate
@@ -1314,6 +1313,21 @@
 ETEXI
 
     {
+        .name       = "block_set_hostcache",
+        .args_type  = "device:B,option:b",
+        .params     = "device on|off",
+        .help       = "Change setting of host pagecache",
+        .mhandler.cmd = hmp_block_set_hostcache,
+    },
+
+STEXI
address@hidden block_set_hostcache @var{device} @var{option}
address@hidden block_set_hostcache
+Change host pagecache setting of a block device while guest is running.
+ETEXI
+
+
+    {
         .name       = "expire_password",
         .args_type  = "protocol:s,time:s",
         .params     = "protocol time",
Index: qemu/qmp-commands.hx
===================================================================
--- qemu.orig/qmp-commands.hx    2012-06-19 15:52:43.552601213 +0530
+++ qemu/qmp-commands.hx    2012-06-19 18:37:32.557638142 +0530
@@ -821,7 +821,31 @@
 
 EQMP
 
+
     {
+        .name       = "block_set_hostcache",
+        .args_type  = "device:B,option:b",
+        .mhandler.cmd_new = qmp_marshal_input_block_set_hostcache,
+    },
+
+SQMP
+block_set_hostcache
+-------------------
+
+Change host pagecache setting of a block device
+
+Arguments:
+
+- "device": the device's ID, must be unique (json-string)
+- "option": hostcache setting (json-bool)
+
+Example:
+-> { "execute": "block_set_hostcache", "arguments": { "device": "ide0-hd0", "option": false } }
+<- { "return": {} }
+
+EQMP
+
+    {
         .name       = "balloon",
         .args_type  = "value:M",
         .mhandler.cmd_new = qmp_marshal_input_balloon,
Index: qemu/qapi-schema.json
===================================================================
--- qemu.orig/qapi-schema.json    2012-06-19 17:24:34.335927717 +0530
+++ qemu/qapi-schema.json    2012-06-19 17:24:54.128025861 +0530
@@ -1598,6 +1598,22 @@
 { 'command': 'block_set_io_throttle',
   'data': { 'device': 'str', 'bps': 'int', 'bps_rd': 'int', 'bps_wr': 'int',
             'iops': 'int', 'iops_rd': 'int', 'iops_wr': 'int' } }
+##
+# @block_set_hostcache:
+#
+# Change host pagecache setting of a block device
+#
+# @device: name of the block device
+#
+# @option: hostcache setting (true/false)
+#
+# Returns: Nothing on success
+#          If @device is not a valid block device, DeviceNotFound
+#
+# Since: 1.2
+##
+{ 'command': 'block_set_hostcache',
+  'data': { 'device': 'str', 'option': 'bool' } }
 
 ##
 # @block-stream:
Index: qemu/hmp.c
===================================================================
--- qemu.orig/hmp.c    2012-06-19 17:24:34.335927717 +0530
+++ qemu/hmp.c    2012-06-19 17:24:54.128025861 +0530
@@ -837,6 +837,15 @@
     hmp_handle_error(mon, &err);
 }
 
+void hmp_block_set_hostcache(Monitor *mon, const QDict *qdict)
+{
+    Error *err = NULL;
+
+    qmp_block_set_hostcache(qdict_get_str(qdict, "device"),
+                              qdict_get_bool(qdict, "option"), &err);
+    hmp_handle_error(mon, &err);
+}
+
 void hmp_block_stream(Monitor *mon, const QDict *qdict)
 {
     Error *error = NULL;
Index: qemu/hmp.h
===================================================================
--- qemu.orig/hmp.h    2012-06-19 15:52:43.500600959 +0530
+++ qemu/hmp.h    2012-06-19 17:24:54.128025861 +0530
@@ -64,5 +64,6 @@
 void hmp_dump_guest_memory(Monitor *mon, const QDict *qdict);
 void hmp_netdev_add(Monitor *mon, const QDict *qdict);
 void hmp_netdev_del(Monitor *mon, const QDict *qdict);
+void hmp_block_set_hostcache(Monitor *mon, const QDict *qdict);
 
 #endif