Re: [Qemu-devel] [PATCH 4/6] block: Make bdrv_load/save_vmstate coroutine_fns

[Eric Blake]

On 06/10/2016 10:05 AM, Kevin Wolf wrote:
> This allows drivers to share code between normal I/O and vmstate
> accesses.
> 
> Signed-off-by: Kevin Wolf 
> ---
>  block/io.c| 80 
> ++-
>  include/block/block_int.h | 10 +++---
>  2 files changed, 64 insertions(+), 26 deletions(-)
> 

Reviewed-by: Eric Blake 

-- 
Eric Blake   eblake redhat com+1-919-301-3266
Libvirt virtualization library http://libvirt.org



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[Qemu-devel] [PATCH 4/6] block: Make bdrv_load/save_vmstate coroutine_fns

[Kevin Wolf]

This allows drivers to share code between normal I/O and vmstate
accesses.

Signed-off-by: Kevin Wolf 
---
 block/io.c| 80 ++-
 include/block/block_int.h | 10 +++---
 2 files changed, 64 insertions(+), 26 deletions(-)

diff --git a/block/io.c b/block/io.c
index bca244c..adf2726 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1831,6 +1831,62 @@ int bdrv_write_compressed(BlockDriverState *bs, int64_t 
sector_num,
 return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors);
 }
 
+typedef struct BdrvVmstateCo {
+BlockDriverState*bs;
+QEMUIOVector*qiov;
+int64_t pos;
+boolis_read;
+int ret;
+} BdrvVmstateCo;
+
+static int coroutine_fn
+bdrv_co_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
+   bool is_read)
+{
+BlockDriver *drv = bs->drv;
+
+if (!drv) {
+return -ENOMEDIUM;
+} else if (drv->bdrv_load_vmstate) {
+return is_read ? drv->bdrv_load_vmstate(bs, qiov, pos)
+   : drv->bdrv_save_vmstate(bs, qiov, pos);
+} else if (bs->file) {
+return bdrv_co_rw_vmstate(bs->file->bs, qiov, pos, is_read);
+}
+
+return -ENOTSUP;
+}
+
+static void bdrv_co_rw_vmstate_entry(void *opaque)
+{
+BdrvVmstateCo *co = opaque;
+co->ret = bdrv_co_rw_vmstate(co->bs, co->qiov, co->pos, co->is_read);
+}
+
+static inline int
+bdrv_rw_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos,
+bool is_read)
+{
+if (qemu_in_coroutine()) {
+return bdrv_co_rw_vmstate(bs, qiov, pos, is_read);
+} else {
+BdrvVmstateCo data = {
+.bs = bs,
+.qiov   = qiov,
+.pos= pos,
+.is_read= is_read,
+.ret= -EINPROGRESS,
+};
+Coroutine *co = qemu_coroutine_create(bdrv_co_rw_vmstate_entry);
+
+qemu_coroutine_enter(co, );
+while (data.ret == -EINPROGRESS) {
+aio_poll(bdrv_get_aio_context(bs), true);
+}
+return data.ret;
+}
+}
+
 int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
   int64_t pos, int size)
 {
@@ -1853,17 +1909,7 @@ int bdrv_save_vmstate(BlockDriverState *bs, const 
uint8_t *buf,
 
 int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
 {
-BlockDriver *drv = bs->drv;
-
-if (!drv) {
-return -ENOMEDIUM;
-} else if (drv->bdrv_save_vmstate) {
-return drv->bdrv_save_vmstate(bs, qiov, pos);
-} else if (bs->file) {
-return bdrv_writev_vmstate(bs->file->bs, qiov, pos);
-}
-
-return -ENOTSUP;
+return bdrv_rw_vmstate(bs, qiov, pos, false);
 }
 
 int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
@@ -1887,17 +1933,7 @@ int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
 
 int bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos)
 {
-BlockDriver *drv = bs->drv;
-
-if (!drv) {
-return -ENOMEDIUM;
-} else if (drv->bdrv_load_vmstate) {
-return drv->bdrv_load_vmstate(bs, qiov, pos);
-} else if (bs->file) {
-return bdrv_readv_vmstate(bs->file->bs, qiov, pos);
-}
-
-return -ENOTSUP;
+return bdrv_rw_vmstate(bs, qiov, pos, true);
 }
 
 /**/
diff --git a/include/block/block_int.h b/include/block/block_int.h
index f9a32cc..1fe0811 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -224,10 +224,12 @@ struct BlockDriver {
 int (*bdrv_get_info)(BlockDriverState *bs, BlockDriverInfo *bdi);
 ImageInfoSpecific *(*bdrv_get_specific_info)(BlockDriverState *bs);
 
-int (*bdrv_save_vmstate)(BlockDriverState *bs, QEMUIOVector *qiov,
- int64_t pos);
-int (*bdrv_load_vmstate)(BlockDriverState *bs, QEMUIOVector *qiov,
- int64_t pos);
+int coroutine_fn (*bdrv_save_vmstate)(BlockDriverState *bs,
+  QEMUIOVector *qiov,
+  int64_t pos);
+int coroutine_fn (*bdrv_load_vmstate)(BlockDriverState *bs,
+  QEMUIOVector *qiov,
+  int64_t pos);
 
 int (*bdrv_change_backing_file)(BlockDriverState *bs,
 const char *backing_file, const char *backing_fmt);
-- 
1.8.3.1