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 @@ -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, + }, + +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