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block: access copy_on_read with atomic ops

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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-2-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This commit is contained in:
Paolo Bonzini 2017-06-05 14:38:50 +02:00 • committed by Fam Zheng
parent 79f24568e5
commit d3faa13e5f
4 changed files with 15 additions and 12 deletions
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8
block/io.c
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@ -130,13 +130,13 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error **errp)
*/
void bdrv_enable_copy_on_read(BlockDriverState *bs)
{
bs->copy_on_read++;
atomic_inc(&bs->copy_on_read);
}
void bdrv_disable_copy_on_read(BlockDriverState *bs)
{
assert(bs->copy_on_read > 0);
bs->copy_on_read--;
int old = atomic_fetch_dec(&bs->copy_on_read);
assert(old >= 1);
}
/* Check if any requests are in-flight (including throttled requests) */
@ -1144,7 +1144,7 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child,
bdrv_inc_in_flight(bs);
/* Don't do copy-on-read if we read data before write operation */
if (bs->copy_on_read && !(flags & BDRV_REQ_NO_SERIALISING)) {
if (atomic_read(&bs->copy_on_read) && !(flags & BDRV_REQ_NO_SERIALISING)) {
flags |= BDRV_REQ_COPY_ON_READ;
}