[Qemu-devel] [PULL 12/69] block: Introduce .bdrv_co_preadv/pwritev BlockDriver function

[Kevin Wolf <kwolf@redhat.com>]

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>
---
 block/io.c                | 28 ++++++++++++++++++++++------
 include/block/block_int.h |  4 ++++
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/block/io.c b/block/io.c
index feddb71..70caadd 100644
--- 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 804bc1d..565f795 100644
--- 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;
 
-- 
1.8.3.1