commit a0d64a61db602696f4f1895a890c65eda5b3b618
author Alberto Garcia <berto@igalia.com> Wed Nov 04 15:15:36 2015 +0200
committer Kevin Wolf <kwolf@redhat.com> Wed Nov 11 16:25:47 2015 +0100
tree a448fb1c4f0a3b60b0fb09f0bd81beab9ef748db
parent 5ac724184c286b367525035eabf4b8bb4a386c54

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

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>

block.c

diff --git a/block.c b/block.c
index 3493501..cffac75 100644
--- a/block.c
+++ b/block.c
@@ -1907,7 +1907,7 @@
     }
 
     /* 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 @@
         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 @@
     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);
     }