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throttle: Use bs->throttle_state instead of bs->io_limits_enabled

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There are two ways to check for I/O limits in a BlockDriverState:

- bs->throttle_state: if this pointer is not NULL, it means that this
  BDS is member of a throttling group, its ThrottleTimers structure
  has been initialized and its I/O limits are ready to be applied.

- bs->io_limits_enabled: if true it means that the throttle_state
  pointer is valid _and_ the limits are currently enabled.

The latter is used in several places to check whether a BDS has I/O
limits configured, but what it really checks is whether requests
are being throttled or not. For example, io_limits_enabled can be
temporarily set to false in cases like bdrv_read_unthrottled() without
otherwise touching the throtting configuration of that BDS.

This patch replaces bs->io_limits_enabled with bs->throttle_state in
all cases where what we really want to check is the existence of I/O
limits, not whether they are currently enabled or not.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Alberto Garcia 2015-11-04 15:15:36 +02:00 committed by Kevin Wolf
parent 5ac724184c
commit a0d64a61db
4 changed files with 10 additions and 7 deletions
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6
block.c
View file

@ -1907,7 +1907,7 @@ void bdrv_close(BlockDriverState *bs)
}
/* Disable I/O limits and drain all pending throttled requests */
if (bs->io_limits_enabled) {
if (bs->throttle_state) {
bdrv_io_limits_disable(bs);
}
@ -3712,7 +3712,7 @@ void bdrv_detach_aio_context(BlockDriverState *bs)
baf->detach_aio_context(baf->opaque);
}
if (bs->io_limits_enabled) {
if (bs->throttle_state) {
throttle_timers_detach_aio_context(&bs->throttle_timers);
}
if (bs->drv->bdrv_detach_aio_context) {
@ -3748,7 +3748,7 @@ void bdrv_attach_aio_context(BlockDriverState *bs,
if (bs->drv->bdrv_attach_aio_context) {
bs->drv->bdrv_attach_aio_context(bs, new_context);
}
if (bs->io_limits_enabled) {
if (bs->throttle_state) {
throttle_timers_attach_aio_context(&bs->throttle_timers, new_context);
}

2
block/qapi.c
View file

@ -64,7 +64,7 @@ BlockDeviceInfo *bdrv_block_device_info(BlockDriverState *bs, Error **errp)
info->backing_file_depth = bdrv_get_backing_file_depth(bs);
info->detect_zeroes = bs->detect_zeroes;
if (bs->io_limits_enabled) {
if (bs->throttle_state) {
ThrottleConfig cfg;
throttle_group_get_config(bs, &cfg);

4
blockdev.c
View file

@ -2361,14 +2361,14 @@ void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
if (throttle_enabled(&cfg)) {
/* Enable I/O limits if they're not enabled yet, otherwise
* just update the throttling group. */
if (!bs->io_limits_enabled) {
if (!bs->throttle_state) {
bdrv_io_limits_enable(bs, has_group ? group : device);
} else if (has_group) {
bdrv_io_limits_update_group(bs, group);
}
/* Set the new throttling configuration */
bdrv_set_io_limits(bs, &cfg);
} else if (bs->io_limits_enabled) {
} else if (bs->throttle_state) {
/* If all throttling settings are set to 0, disable I/O limits */
bdrv_io_limits_disable(bs);
}

5
include/block/block_int.h
View file

@ -390,7 +390,10 @@ struct BlockDriverState {
/* number of in-flight serialising requests */
unsigned int serialising_in_flight;
/* I/O throttling */
/* I/O throttling.
* throttle_state tells us if this BDS has I/O limits configured.
* io_limits_enabled tells us if they are currently being
* enforced, but it can be temporarily set to false */
CoQueue throttled_reqs[2];
bool io_limits_enabled;
/* The following fields are protected by the ThrottleGroup lock.