On Wed, 01 Feb 2012 08:36:41 +0530
Supriya Kannery <supri...@linux.vnet.ibm.com> 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 <supri...@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
> @@ -808,6 +808,35 @@ 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_REOPEN_FILE_FAILED, bs->filename);
OPEN_FILE_FAILED is fine.
> + 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) {
> @@ -870,6 +899,33 @@ void bdrv_drain_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 */
> + 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
> @@ -119,6 +119,7 @@ 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);
> @@ -160,6 +161,7 @@ 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
> @@ -1080,3 +1080,29 @@ 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.
> +*/
> +int do_block_set_hostcache(Monitor *mon, const QDict *qdict,
> + QObject **ret_data)
This is not a QAPI command, please read docs/writing-qmp-commands.txt to know
how to write QMP commands using the QAPI.
> +{
> + 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
> @@ -62,4 +62,6 @@ void qmp_change_blockdev(const char *dev
> bool has_format, const char *format, Error **errp);
> void do_commit(Monitor *mon, const QDict *qdict);
> int do_drive_del(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
> @@ -796,6 +796,20 @@ ETEXI
> .mhandler.cmd_new = do_migrate,
> },
>
> + {
> + .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{option}
> +@findex block_set_hostcache
> +Change host pagecache setting of a block device while guest is running.
> +ETEXI
> +
>
> STEXI
> @item migrate [-d] [-b] [-i] @var{uri}
> Index: qemu/qmp-commands.hx
> ===================================================================
> --- qemu.orig/qmp-commands.hx
> +++ qemu/qmp-commands.hx
> @@ -698,7 +698,34 @@ 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",
> .mhandler.cmd_new = qmp_marshal_input_balloon,
>
