[PATCH] nbd: no need to check all the connections one by one if all are dead

[xiubli]

From: Xiubo Li <xiu...@redhat.com>

If all connections are dead the live_connections should be already
set to 0. And set the nsock->fallback to -1 again if all connections
are dead.

Signed-off-by: Xiubo Li <xiu...@redhat.com>
---
 drivers/block/nbd.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 98be6ca..6da42aa 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -783,13 +783,16 @@ static int find_fallback(struct nbd_device *nbd, int 
index)
                return new_index;
        }
 
+       if (atomic_read(&config->live_connections) <= 0) {
+               dev_err_ratelimited(disk_to_dev(nbd->disk),
+                                   "Dead connection, failed to find a 
fallback\n");
+               goto out;
+       }
+
        if (fallback >= 0 && fallback < config->num_connections &&
-           !config->socks[fallback]->dead)
+               !config->socks[fallback]->dead) {
                return fallback;
-
-       if (nsock->fallback_index < 0 ||
-           nsock->fallback_index >= config->num_connections ||
-           config->socks[nsock->fallback_index]->dead) {
+       } else {
                int i;
                for (i = 0; i < config->num_connections; i++) {
                        if (i == index)
@@ -799,14 +802,10 @@ static int find_fallback(struct nbd_device *nbd, int 
index)
                                break;
                        }
                }
-               nsock->fallback_index = new_index;
-               if (new_index < 0) {
-                       dev_err_ratelimited(disk_to_dev(nbd->disk),
-                                           "Dead connection, failed to find a 
fallback\n");
-                       return new_index;
-               }
        }
-       new_index = nsock->fallback_index;
+
+out:
+       nsock->fallback_index = new_index;
        return new_index;
 }
 
-- 
1.8.3.1