[4/6] block: Make bdrv_load/save_vmstate coroutine_fns

Commit Message

Kevin Wolf June 10, 2016, 4:05 p.m. UTC

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

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

Comments

Eric Blake June 10, 2016, 10:33 p.m. UTC | #1

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 <[e-mail]>
> ---
>  block/io.c                | 80 ++++++++++++++++++++++++++++++++++-------------
>  include/block/block_int.h | 10 +++---
>  2 files changed, 64 insertions(+), 26 deletions(-)
> 

Reviewed-by: Eric Blake <[e-mail]>

Stefan Hajnoczi June 16, 2016, 8:49 a.m. UTC | #2

On Fri, Jun 10, 2016 at 06:05:20PM +0200, Kevin Wolf wrote:
> +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)

This should also be coroutine_fn.

Patch

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;
+    bool                is_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, &data);
+        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);