block: add .bdrv_co_is_allocated()
This patch adds the .bdrv_co_is_allocated() interface which is identical
to .bdrv_is_allocated() but runs in coroutine context. Running in
coroutine context implies that other coroutines might be performing I/O
at the same time. Therefore it must be safe to run while the following
BlockDriver functions are in-flight:
.bdrv_co_readv()
.bdrv_co_writev()
.bdrv_co_flush()
.bdrv_co_is_allocated()
The new .bdrv_co_is_allocated() interface is useful because it can be
used when a VM is running, whereas .bdrv_is_allocated() is a synchronous
interface that does not cope with parallel requests.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/block.c b/block.c
index 0d5bee0..611c429 100644
--- a/block.c
+++ b/block.c
@@ -1887,6 +1887,26 @@
return 1;
}
+typedef struct BdrvCoIsAllocatedData {
+ BlockDriverState *bs;
+ int64_t sector_num;
+ int nb_sectors;
+ int *pnum;
+ int ret;
+ bool done;
+} BdrvCoIsAllocatedData;
+
+/* Coroutine wrapper for bdrv_is_allocated() */
+static void coroutine_fn bdrv_is_allocated_co_entry(void *opaque)
+{
+ BdrvCoIsAllocatedData *data = opaque;
+ BlockDriverState *bs = data->bs;
+
+ data->ret = bs->drv->bdrv_co_is_allocated(bs, data->sector_num,
+ data->nb_sectors, data->pnum);
+ data->done = true;
+}
+
/*
* Returns true iff the specified sector is present in the disk image. Drivers
* not implementing the functionality are assumed to not support backing files,
@@ -1902,6 +1922,23 @@
int *pnum)
{
int64_t n;
+ if (bs->drv->bdrv_co_is_allocated) {
+ Coroutine *co;
+ BdrvCoIsAllocatedData data = {
+ .bs = bs,
+ .sector_num = sector_num,
+ .nb_sectors = nb_sectors,
+ .pnum = pnum,
+ .done = false,
+ };
+
+ co = qemu_coroutine_create(bdrv_is_allocated_co_entry);
+ qemu_coroutine_enter(co, &data);
+ while (!data.done) {
+ qemu_aio_wait();
+ }
+ return data.ret;
+ }
if (!bs->drv->bdrv_is_allocated) {
if (sector_num >= bs->total_sectors) {
*pnum = 0;
