[Qemu-devel] [PATCH 1/3] nbd: Only try to send flush/discard commands if connected to the NBD server

[nick]

This is unlikely to come up now, but is a necessary prerequisite for 
reconnection
behaviour.

Signed-off-by: Nick Thomas <n...@bytemark.co.uk>
---
 block/nbd.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)


diff --git a/block/nbd.c b/block/nbd.c
index 2bce47b..9536408 100644
--- a/block/nbd.c
+++ b/block/nbd.c
@@ -71,6 +71,11 @@ typedef struct BDRVNBDState {
     char *host_spec;
 } BDRVNBDState;
 
+static bool nbd_is_connected(BDRVNBDState *s)
+{
+    return s->sock >= 0;
+}
+
 static int nbd_config(BDRVNBDState *s, const char *filename, int flags)
 {
     char *file;
@@ -309,6 +314,7 @@ static void nbd_teardown_connection(BlockDriverState *bs)
 
     qemu_aio_set_fd_handler(s->sock, NULL, NULL, NULL, NULL);
     closesocket(s->sock);
+    s->sock = -1;
 }
 
 static int nbd_open(BlockDriverState *bs, const char* filename, int flags)
@@ -316,6 +322,8 @@ static int nbd_open(BlockDriverState *bs, const char* filename, int flags)
     BDRVNBDState *s = bs->opaque;
     int result;
 
+    s->sock = -1;
+
     qemu_co_mutex_init(&s->send_mutex);
     qemu_co_mutex_init(&s->free_sema);
 
@@ -431,7 +439,7 @@ static int nbd_co_flush(BlockDriverState *bs)
     struct nbd_reply reply;
     ssize_t ret;
 
-    if (!(s->nbdflags & NBD_FLAG_SEND_FLUSH)) {
+    if (!nbd_is_connected(s) || !(s->nbdflags & NBD_FLAG_SEND_FLUSH)) {
         return 0;
     }
 
@@ -462,7 +470,7 @@ static int nbd_co_discard(BlockDriverState *bs, int64_t sector_num,
     struct nbd_reply reply;
     ssize_t ret;
 
-    if (!(s->nbdflags & NBD_FLAG_SEND_TRIM)) {
+    if (!nbd_is_connected(s) || !(s->nbdflags & NBD_FLAG_SEND_TRIM)) {
         return 0;
     }
     request.type = NBD_CMD_TRIM;
@@ -515,3 +523,4 @@ static void bdrv_nbd_init(void)
 }
 
 block_init(bdrv_nbd_init);
+