[Qemu-block] [PATCH v6 05/20] block: Introduce byte-based aio read/write

[Eric Blake]

blk_aio_readv() and blk_aio_writev() are annoying in that they
can't access sub-sector granularity, and cannot pass flags.
Also, they require the caller to pass redundant information
about the size of the I/O.

Add new blk_aio_preadv() and blk_aio_pwritev() functions to fix
the flaws. The next few patches will upgrade callers, then
finally delete the old interfaces.

Signed-off-by: Eric Blake <address@hidden>
---
 include/sysemu/block-backend.h |  6 ++++++
 block/block-backend.c          | 16 ++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 851376b..8d7839c 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -110,9 +110,15 @@ int64_t blk_nb_sectors(BlockBackend *blk);
 BlockAIOCB *blk_aio_readv(BlockBackend *blk, int64_t sector_num,
                           QEMUIOVector *iov, int nb_sectors,
                           BlockCompletionFunc *cb, void *opaque);
+BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset,
+                           QEMUIOVector *iov, BdrvRequestFlags flags,
+                           BlockCompletionFunc *cb, void *opaque);
 BlockAIOCB *blk_aio_writev(BlockBackend *blk, int64_t sector_num,
                            QEMUIOVector *iov, int nb_sectors,
                            BlockCompletionFunc *cb, void *opaque);
+BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
+                            QEMUIOVector *iov, BdrvRequestFlags flags,
+                            BlockCompletionFunc *cb, void *opaque);
 BlockAIOCB *blk_aio_flush(BlockBackend *blk,
                           BlockCompletionFunc *cb, void *opaque);
 BlockAIOCB *blk_aio_discard(BlockBackend *blk,
diff --git a/block/block-backend.c b/block/block-backend.c
index f8f88a6..104852d 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -998,6 +998,14 @@ BlockAIOCB *blk_aio_readv(BlockBackend *blk, int64_t 
sector_num,
                         blk_aio_read_entry, 0, cb, opaque);
 }

+BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset,
+                           QEMUIOVector *iov, BdrvRequestFlags flags,
+                           BlockCompletionFunc *cb, void *opaque)
+{
+    return blk_aio_prwv(blk, offset, iov->size, iov,
+                        blk_aio_read_entry, flags, cb, opaque);
+}
+
 BlockAIOCB *blk_aio_writev(BlockBackend *blk, int64_t sector_num,
                            QEMUIOVector *iov, int nb_sectors,
                            BlockCompletionFunc *cb, void *opaque)
@@ -1011,6 +1019,14 @@ BlockAIOCB *blk_aio_writev(BlockBackend *blk, int64_t 
sector_num,
                         blk_aio_write_entry, 0, cb, opaque);
 }

+BlockAIOCB *blk_aio_pwritev(BlockBackend *blk, int64_t offset,
+                            QEMUIOVector *iov, BdrvRequestFlags flags,
+                            BlockCompletionFunc *cb, void *opaque)
+{
+    return blk_aio_prwv(blk, offset, iov->size, iov,
+                        blk_aio_write_entry, flags, cb, opaque);
+}
+
 BlockAIOCB *blk_aio_flush(BlockBackend *blk,
                           BlockCompletionFunc *cb, void *opaque)
 {
-- 
2.5.5