block: Allow BDRV_REQ_FUA through blk_pwrite()
We have several block drivers that understand BDRV_REQ_FUA,
and emulate it in the block layer for the rest by a full flush.
But without a way to actually request BDRV_REQ_FUA during a
pass-through blk_pwrite(), FUA-aware block drivers like NBD are
forced to repeat the emulation logic of a full flush regardless
of whether the backend they are writing to could do it more
efficiently.
This patch just wires up a flags argument; followup patches
will actually make use of it in the NBD driver and in qemu-io.
Signed-off-by: Eric Blake <eblake@redhat.com>
Acked-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index c62b6fe..6991b26 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -102,7 +102,8 @@
int nb_sectors, BdrvRequestFlags flags,
BlockCompletionFunc *cb, void *opaque);
int blk_pread(BlockBackend *blk, int64_t offset, void *buf, int count);
-int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int count);
+int blk_pwrite(BlockBackend *blk, int64_t offset, const void *buf, int count,
+ BdrvRequestFlags flags);
int64_t blk_getlength(BlockBackend *blk);
void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr);
int64_t blk_nb_sectors(BlockBackend *blk);
