nbd: add support for NBD_CMD_FLAG_FUA

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 15 insertions, 2 deletions

diff --git a/block/nbd.c b/block/nbd.c
index 3f693e3ffa..2f483cddde 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -352,6 +352,10 @@ static int nbd_co_writev_1(BlockDriverState *bs, int64_t sector_num,
     struct nbd_reply reply;
 
     request.type = NBD_CMD_WRITE;
+    if (!bdrv_enable_write_cache(bs) && (s->nbdflags & NBD_FLAG_SEND_FUA)) {
+        request.type |= NBD_CMD_FLAG_FUA;
+    }
+
     request.from = sector_num * 512;
     request.len = nb_sectors * 512;
 
diff --git a/nbd.c b/nbd.c
index 5b718b5973..c597d4733f 100644
--- a/nbd.c
+++ b/nbd.c
@@ -202,7 +202,8 @@ int nbd_negotiate(int csock, off_t size, uint32_t flags)
     memcpy(buf, "NBDMAGIC", 8);
     cpu_to_be64w((uint64_t*)(buf + 8), 0x00420281861253LL);
     cpu_to_be64w((uint64_t*)(buf + 16), size);
-    cpu_to_be32w((uint32_t*)(buf + 24), flags | NBD_FLAG_HAS_FLAGS);
+    cpu_to_be32w((uint32_t*)(buf + 24),
+                 flags | NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_FUA);
     memset(buf + 28, 0, 124);
 
     if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
@@ -630,7 +631,7 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size, uint64_t dev_offset,
     reply.handle = request.handle;
     reply.error = 0;
 
-    switch (request.type) {
+    switch (request.type & NBD_CMD_MASK_COMMAND) {
     case NBD_CMD_READ:
         TRACE("Request type is READ");
 
@@ -692,6 +693,14 @@ int nbd_trip(BlockDriverState *bs, int csock, off_t size, uint64_t dev_offset,
             }
 
             *offset += request.len;
+
+            if (request.type & NBD_CMD_FLAG_FUA) {
+                ret = bdrv_flush(bs);
+                if (ret < 0) {
+                    LOG("flush failed");
+                    reply.error = -ret;
+                }
+            }
         }
 
         if (nbd_send_reply(csock, &reply) == -1)