nbd: correct disconnect behavior

commit c378f70adbc1bbecd9e6db145019f14b2f688c7c upstream.

Currently, when a disconnect is requested by the user (via NBD_DISCONNECT
ioctl) the return from NBD_DO_IT is undefined (it is usually one of
several error codes).  This means that nbd-client does not know if a
manual disconnect was performed or whether a network error occurred.
Because of this, nbd-client's persist mode (which tries to reconnect after
error, but not after manual disconnect) does not always work correctly.

This change fixes this by causing NBD_DO_IT to always return 0 if a user
requests a disconnect.  This means that nbd-client can correctly either
persist the connection (if an error occurred) or disconnect (if the user
requested it).

Signed-off-by: Paul Clements <paul.clements@steeleye.com>
Acked-by: Rob Landley <rob@landley.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/nbd.h b/include/linux/nbd.h
index 4871170a04a0..ae4981ebd18e 100644
--- a/include/linux/nbd.h
+++ b/include/linux/nbd.h
@@ -41,6 +41,7 @@ struct nbd_device {
         u64 bytesize;
         pid_t pid; /* pid of nbd-client, if attached */
         int xmit_timeout;
+        int disconnect; /* a disconnect has been requested by user */
 };
 
 #endif