block: Introduce .bdrv_co_preadv/pwritev BlockDriver function

Many parts of the block layer are already byte granularity. The block
driver interface, however, was still missing an interface that allows
making use of this. This patch introduces a new BlockDriver interface,
which is based on coroutines, vectored, has flags and uses a byte
granularity. This is now the preferred interface for new drivers.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>

diff --git a/block/io.c b/block/io.c
index feddb71b451df8af921653777de4ff8ba056e2b5..70caadd0f50d67f66ca3feb94d9fcbae036f1095 100644 (file)
--- a/block/io.c
+++ b/block/io.c
@@ -803,8 +803,15 @@ static int coroutine_fn bdrv_driver_preadv(BlockDriverState *bs,
                                            QEMUIOVector *qiov, int flags)
 {
     BlockDriver *drv = bs->drv;
-    int64_t sector_num = offset >> BDRV_SECTOR_BITS;
-    unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
+    int64_t sector_num;
+    unsigned int nb_sectors;
+
+    if (drv->bdrv_co_preadv) {
+        return drv->bdrv_co_preadv(bs, offset, bytes, qiov, flags);
+    }
+
+    sector_num = offset >> BDRV_SECTOR_BITS;
+    nb_sectors = bytes >> BDRV_SECTOR_BITS;
 
     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
@@ -834,10 +841,18 @@ static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs,
                                             QEMUIOVector *qiov, int flags)
 {
     BlockDriver *drv = bs->drv;
-    int64_t sector_num = offset >> BDRV_SECTOR_BITS;
-    unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS;
+    int64_t sector_num;
+    unsigned int nb_sectors;
     int ret;
 
+    if (drv->bdrv_co_pwritev) {
+        ret = drv->bdrv_co_pwritev(bs, offset, bytes, qiov, flags);
+        goto emulate_flags;
+    }
+
+    sector_num = offset >> BDRV_SECTOR_BITS;
+    nb_sectors = bytes >> BDRV_SECTOR_BITS;
+
     assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0);
     assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
     assert((bytes >> BDRV_SECTOR_BITS) <= BDRV_REQUEST_MAX_SECTORS);
@@ -857,13 +872,14 @@ static int coroutine_fn bdrv_driver_pwritev(BlockDriverState *bs,
         acb = bs->drv->bdrv_aio_writev(bs, sector_num, qiov, nb_sectors,
                                        bdrv_co_io_em_complete, &co);
         if (acb == NULL) {
-            return -EIO;
+            ret = -EIO;
         } else {
             qemu_coroutine_yield();
-            return co.ret;
+            ret = co.ret;
         }
     }
 
+emulate_flags:
     if (ret == 0 && (flags & BDRV_REQ_FUA) &&
         !(drv->supported_write_flags & BDRV_REQ_FUA))
     {

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 804bc1d60b3fc5d0268d131fb85de9b1459f0f22..565f7957581b590c340217b54253329109de8739 100644 (file)
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -153,10 +153,14 @@ struct BlockDriver {
 
     int coroutine_fn (*bdrv_co_readv)(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
+    int coroutine_fn (*bdrv_co_preadv)(BlockDriverState *bs,
+        uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
     int coroutine_fn (*bdrv_co_writev)(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
     int coroutine_fn (*bdrv_co_writev_flags)(BlockDriverState *bs,
         int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, int flags);
+    int coroutine_fn (*bdrv_co_pwritev)(BlockDriverState *bs,
+        uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags);
 
     int supported_write_flags;