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

[Shrinidhi Joshi <spjoshi31@gmail.com>]

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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 <supriyak@linux.vnet.ibm.com>
> >
> > ---
> > 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
> > +@item block_set_hostcache @var{device} @var{option}
> > +@findex 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 <supriyak@linux.vnet.ibm.com>

Signed-off-by: Shrinidhi Joshi <spjoshi31@gmail.com>
---
  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
+@item block_set_hostcache @var{device} @var{option}
+@findex 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




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