From patchwork Sun Oct 30 10:34:29 2011
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
X-Patchwork-Submitter: Supriya Kannery <supriyak@linux.vnet.ibm.com>
X-Patchwork-Id: 122594
Return-Path: <qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>
X-Original-To: incoming@patchwork.ozlabs.org
Delivered-To: patchwork-incoming@bilbo.ozlabs.org
Received: from lists.gnu.org (lists.gnu.org [140.186.70.17])
	(using TLSv1 with cipher AES256-SHA (256/256 bits))
	(Client did not present a certificate)
	by ozlabs.org (Postfix) with ESMTPS id 55B44B6F77
	for <incoming@patchwork.ozlabs.org>;
	Sun, 30 Oct 2011 21:35:33 +1100 (EST)
Received: from localhost ([::1]:58998 helo=lists.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.71) (envelope-from
	<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>)
	id 1RKSjd-0003uD-Jx
	for incoming@patchwork.ozlabs.org; Sun, 30 Oct 2011 06:35:25 -0400
Received: from eggs.gnu.org ([140.186.70.92]:45839)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <supriyak@linux.vnet.ibm.com>) id 1RKSjP-0003SH-QQ
	for qemu-devel@nongnu.org; Sun, 30 Oct 2011 06:35:13 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <supriyak@linux.vnet.ibm.com>) id 1RKSjO-0002eL-4h
	for qemu-devel@nongnu.org; Sun, 30 Oct 2011 06:35:11 -0400
Received: from e34.co.us.ibm.com ([32.97.110.152]:57718)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <supriyak@linux.vnet.ibm.com>) id 1RKSjN-0002e0-Qq
	for qemu-devel@nongnu.org; Sun, 30 Oct 2011 06:35:10 -0400
Received: from /spool/local
	by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use
	Only! Violators will be prosecuted
	for <qemu-devel@nongnu.org> from <supriyak@linux.vnet.ibm.com>;
	Sun, 30 Oct 2011 04:35:08 -0600
Received: from d03relay04.boulder.ibm.com ([9.17.195.106])
	by e34.co.us.ibm.com ([192.168.1.134]) with IBM ESMTP SMTP Gateway:
	Authorized Use Only! Violators will be prosecuted;
	Sun, 30 Oct 2011 04:34:43 -0600
Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com
	[9.17.195.170])
	by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id
	p9UAYghT142890
	for <qemu-devel@nongnu.org>; Sun, 30 Oct 2011 04:34:42 -0600
Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1])
	by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP
	id p9UAYf0A000409
	for <qemu-devel@nongnu.org>; Sun, 30 Oct 2011 04:34:42 -0600
Received: from skannery.in.ibm.com ([9.77.202.63])
	by d03av04.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP
	id p9UAYUxx032621; Sun, 30 Oct 2011 04:34:31 -0600
From: Supriya Kannery <supriyak@linux.vnet.ibm.com>
To: qemu-devel@nongnu.org
Date: Sun, 30 Oct 2011 16:04:29 +0530
Message-Id: <20111030103429.31685.89126.sendpatchset@skannery.in.ibm.com>
In-Reply-To: <20111030103327.31685.17045.sendpatchset@skannery.in.ibm.com>
References: <20111030103327.31685.17045.sendpatchset@skannery.in.ibm.com>
x-cbid: 11103010-1780-0000-0000-00000091707A
X-detected-operating-system: by eggs.gnu.org: Genre and OS details not
	recognized.
X-Received-From: 32.97.110.152
Cc: Kevin Wolf <kwolf@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>,
	Christoph Hellwig <hch@lst.de>
Subject: [Qemu-devel] [v8 Patch 3/6]Qemu: Cmd "block_set_hostcache" for
	dynamic cache change
X-BeenThere: qemu-devel@nongnu.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org
Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org

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
@@ -693,6 +693,34 @@ 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();
+    if (bdrv_flush(bs)) {
+        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_REOPEN_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)
 {
     if (bs->drv) {
@@ -730,6 +758,32 @@ void bdrv_close_all(void)
     }
 }
 
+int bdrv_change_hostcache(BlockDriverState *bs, bool enable_host_cache)
+{
+    int bdrv_flags = bs->open_flags;
+
+    /* set hostcache flags (without changing WCE/flush bits) */
+    if (enable_host_cache) {
+        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) {
+        return 0;
+    }
+
+    if (bdrv_is_inserted(bs)) {
+        /* Reopen file with changed set of flags */
+        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
@@ -109,6 +109,7 @@ 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);
@@ -143,6 +144,7 @@ void 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
@@ -776,3 +776,29 @@ int do_block_resize(Monitor *mon, const 
 
     return 0;
 }
+
+
+/*
+ * Change host page cache setting while guest is running.
+*/
+int do_block_set_hostcache(Monitor *mon, const QDict *qdict,
+                           QObject **ret_data)
+{
+    BlockDriverState *bs = NULL;
+    int enable;
+    const char *device;
+
+    /* Validate device */
+    device = qdict_get_str(qdict, "device");
+    bs = bdrv_find(device);
+    if (!bs) {
+        qerror_report(QERR_DEVICE_NOT_FOUND, device);
+        return -1;
+    }
+
+    /* Read hostcache setting */
+    enable = qdict_get_bool(qdict, "option");
+    return bdrv_change_hostcache(bs, enable);
+
+}
+
Index: qemu/blockdev.h
===================================================================
--- qemu.orig/blockdev.h
+++ qemu/blockdev.h
@@ -65,5 +65,7 @@ int do_change_block(Monitor *mon, const 
 int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data);
 int do_snapshot_blkdev(Monitor *mon, const QDict *qdict, QObject **ret_data);
 int do_block_resize(Monitor *mon, const QDict *qdict, QObject **ret_data);
+int do_block_set_hostcache(Monitor *mon, const QDict *qdict,
+                           QObject **ret_data);
 
 #endif
Index: qemu/hmp-commands.hx
===================================================================
--- qemu.orig/hmp-commands.hx
+++ qemu/hmp-commands.hx
@@ -70,6 +70,20 @@ but should be used with extreme caution.
 resizes image files, it can not resize block devices like LVM volumes.
 ETEXI
 
+    {
+        .name       = "block_set_hostcache",
+        .args_type  = "device:B,option:b",
+        .params     = "device on|off",
+        .help       = "Change setting of host pagecache",
+        .user_print = monitor_user_noop,
+        .mhandler.cmd_new = do_block_set_hostcache,
+    },
+STEXI
+@item block_set_hostcache @var{device} @var{setting}
+@findex block_set_hostcache
+Change host pagecache setting of a block device while guest is running.
+ETEXI
+
 
     {
         .name       = "eject",
Index: qemu/qmp-commands.hx
===================================================================
--- qemu.orig/qmp-commands.hx
+++ qemu/qmp-commands.hx
@@ -718,7 +718,34 @@ Example:
 
 EQMP
 
+
     {
+        .name       = "block_set_hostcache",
+        .args_type  = "device:B,option:b",
+        .params     = "device on|off",
+        .help       = "Change setting of host pagecache (true|false)",
+        .user_print = monitor_user_noop,
+        .mhandler.cmd_new = do_block_set_hostcache,
+    },
+
+SQMP
+block_set_hostcache
+-------------------
+
+Change host pagecache setting of a block device (on|off)
+
+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",
         .params     = "target",