Re: [Qemu-devel] [V4 Patch 3/4 - Updated]Qemu: Command "block_set" for dynamic block params change

[Supriya Kannery <supriyak@in.ibm.com>]

On 07/13/2011 06:37 PM, Supriya Kannery wrote:
> Updated "block_set" command to accept multiple -drive parameters.
> Also, added code for re-opening of device file with original flags,
> incase opening file using changed hostcache setting fails.
>
> ----------------------------------------------------------------------
> New command "block_set" added for dynamically changing any of the block
> device parameters. For now, dynamic setting of hostcache params using this
> command is implemented. Other block device parameters, can be integrated
> in similar lines.
>
> Signed-off-by: Supriya Kannery <supriyak@in.ibm.com>
>
> ---
> block.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> block.h | 2 +
> blockdev.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> blockdev.h | 1
> hmp-commands.hx | 14 +++++++++++++
> qemu-config.c | 13 ++++++++++++
> qemu-option.c | 25 +++++++++++++++++++++++
> qemu-option.h | 2 +
> qmp-commands.hx | 28 ++++++++++++++++++++++++++
> 9 files changed, 205 insertions(+)
>
> Index: qemu/block.c
> ===================================================================
> --- qemu.orig/block.c
> +++ qemu/block.c
> @@ -651,6 +651,40 @@ unlink_and_fail:
> return ret;
> }
>
> +int bdrv_reopen(BlockDriverState *bs, int bdrv_flags)
> +{
> + BlockDriver *drv = bs->drv;
> + int ret = 0;
> +
> + /* 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;
> + }
> + bdrv_close(bs);
> +
> +
> + ret = bdrv_open(bs, bs->filename, bdrv_flags, drv);
> + if (ret < 0) {
> + /* Reopen failed. Try to open with original flags */
> + error_report("Opening file with changed flags...");
> + qerror_report(QERR_REOPEN_FILE_FAILED, bs->filename);
> +
> + ret = bdrv_open(bs, bs->filename, bs->open_flags, drv);
> + if (ret < 0) {
> + /*
> + * Reopen failed with orig and modified flags
> + */
> + error_report("Opening file with original flags...");
> + qerror_report(QERR_REOPEN_FILE_FAILED, bs->filename);
> + abort();
> + }
> + }
> +
> + return ret;
> +}
> +
> void bdrv_close(BlockDriverState *bs)
> {
> if (bs->drv) {
> @@ -691,6 +725,32 @@ 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
> @@ -71,6 +71,7 @@ void bdrv_delete(BlockDriverState *bs);
> 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(BlockDriverState *bs, DeviceState *qdev);
> void bdrv_detach(BlockDriverState *bs, DeviceState *qdev);
> @@ -96,6 +97,7 @@ 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
> @@ -793,3 +793,63 @@ int do_block_resize(Monitor *mon, const
>
> return 0;
> }
> +
> +
> +/*
> + * Handle changes to block device settings, like hostcache,
> + * while guest is running.
> +*/
> +int do_block_set(Monitor *mon, const QDict *qdict, QObject **ret_data)
> +{
> + BlockDriverState *bs = NULL;
> + QemuOpts *opts;
> + int enable;
> + const char *device, *driver;
> + int ret;
> +
> + /* Validate device */
> + device = qdict_get_str(qdict, "device");
> + bs = bdrv_find(device);
> + if (!bs) {
> + qerror_report(QERR_DEVICE_NOT_FOUND, device);
> + return -1;
> + }
> +
> + opts = qemu_opts_from_qdict(qemu_find_opts("device"), qdict);
> + if (opts == NULL) {
> + return -1;
> + }
> +
> + /* If input not in "param=value" format, display error */
> + driver = qemu_opt_get(opts, "driver");
> + if (driver != NULL) {
> + error_report("Invalid parameter %s", driver);
> + return -1;
> + }
> +
> + /* Before validating parameters, remove "device" option */
> + ret = qemu_opt_delete(opts, "device");
> + if (ret == 1) {
> + error_report("Specify parameter to be changed");
> + error_report("Usage: block_set device [prop=value][,...]");
> + return 0;
> + }
> +
> + /* Validate parameters with "-drive" parameter list */
> + ret = qemu_validate_opts(opts, "drive");
> + if (ret == -1) {
> + return -1;
> + }
> +
> + /* Check for 'hostcache' parameter */
> + enable = qemu_opt_get_bool(opts, "hostcache", -1);
> + if (enable != -1) {
> + return bdrv_change_hostcache(bs, enable);
> + } else {
> + error_report("Specify 'hostcache=on/off'");
> + }
> +
> + return 0;
> +
> +}
> +
> Index: qemu/blockdev.h
> ===================================================================
> --- qemu.orig/blockdev.h
> +++ qemu/blockdev.h
> @@ -65,5 +65,6 @@ 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(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",
> + .args_type = "device:B,device:O",
> + .params = "device [prop=value][,...]",
> + .help = "Change block device parameters [hostcache=on/off]",
> + .user_print = monitor_user_noop,
> + .mhandler.cmd_new = do_block_set,
> + },
> +STEXI
> +@item block_set @var{config}
> +@findex block_set
> +Change block device parameters (eg: hostcache=on/off) while guest is
> running.
> +ETEXI
> +
>
> {
> .name = "eject",
> Index: qemu/qemu-config.c
> ===================================================================
> --- qemu.orig/qemu-config.c
> +++ qemu/qemu-config.c
> @@ -506,6 +506,19 @@ QemuOptsList *qemu_find_opts(const char
> return find_list(vm_config_groups, group);
> }
>
> +/* Validate given opts list with that of defined vm_group */
> +int qemu_validate_opts(QemuOpts *opts, const char *group)
> +{
> + QemuOptsList *vm_group;
> +
> + vm_group = qemu_find_opts(group);
> + if (vm_group == NULL) {
> + return -1;
> + }
> +
> + return qemu_opts_validate(opts, &vm_group->desc[0]);
> +}
> +
> void qemu_add_opts(QemuOptsList *list)
> {
> int entries, i;
> Index: qemu/qemu-option.c
> ===================================================================
> --- qemu.orig/qemu-option.c
> +++ qemu/qemu-option.c
> @@ -599,6 +599,31 @@ static void qemu_opt_del(QemuOpt *opt)
> qemu_free(opt);
> }
>
> +/*
> + * Delete specified parameter with name "name" from opts
> + * Return
> + * 0 - Deletion Successful
> + * -1 - Param doesn't exist in opts
> + * 1 - Deletion Successful and opts is empty.
> +*/
> +
> +int qemu_opt_delete(QemuOpts *opts, const char *name)
> +{
> + QemuOpt *opt = qemu_opt_find(opts, name);
> + if (opt == NULL) {
> + return -1;
> + }
> +
> + qemu_opt_del(opt);
> +
> + if ((&opts->head)->tqh_first == NULL) {
> + /* opt queue is empty */
> + return 1;
> + }
> +
> + return 0;
> +}
> +
> int qemu_opt_set(QemuOpts *opts, const char *name, const char *value)
> {
> QemuOpt *opt;
> Index: qemu/qemu-option.h
> ===================================================================
> --- qemu.orig/qemu-option.h
> +++ qemu/qemu-option.h
> @@ -121,6 +121,7 @@ int qemu_opts_set(QemuOptsList *list, co
> const char *name, const char *value);
> const char *qemu_opts_id(QemuOpts *opts);
> void qemu_opts_del(QemuOpts *opts);
> +int qemu_opt_delete(QemuOpts *opts, const char *name);
> int qemu_opts_validate(QemuOpts *opts, const QemuOptDesc *desc);
> int qemu_opts_do_parse(QemuOpts *opts, const char *params, const char
> *firstname);
> QemuOpts *qemu_opts_parse(QemuOptsList *list, const char *params, int
> permit_abbrev);
> @@ -131,5 +132,6 @@ typedef int (*qemu_opts_loopfunc)(QemuOp
> int qemu_opts_print(QemuOpts *opts, void *dummy);
> int qemu_opts_foreach(QemuOptsList *list, qemu_opts_loopfunc func, void
> *opaque,
> int abort_on_failure);
> +int qemu_validate_opts(QemuOpts *opts, const char *id);
>
> #endif
> Index: qemu/qmp-commands.hx
> ===================================================================
> --- qemu.orig/qmp-commands.hx
> +++ qemu/qmp-commands.hx
> @@ -693,7 +693,35 @@ Example:
>
> EQMP
>
> +
> {
> + .name = "block_set",
> + .args_type = "device:B,device:O",
> + .params = "device [prop=value][,...]",
> + .help = "Change block device parameters [hostcache=on/off]",
> + .user_print = monitor_user_noop,
> + .mhandler.cmd_new = do_block_set,
> + },
> +
> +SQMP
> +block_set
> +---------
> +
> +Change various block device parameters (eg: hostcache=on/off)
> +
> +Arguments:
> +
> +- "device": the device's ID, must be unique (json-string)
> +- device parameters to be changed (eg: "hostcache": "off")
> +
> +Example:
> +
> +-> { "execute": "block_set", "arguments": { "device": "ide0-hd0",
> "hostcache": "off"} }
> +<- { "return": {} }
> +
> +EQMP
> +
> + {
> .name = "balloon",
> .args_type = "value:M",
> .params = "target",
>
Please review..