[Qemu-trivial] [PATCH 2/2] nbd: Don't validate from and len in NBD_CMD_DISC.

[Hani Benhabiles <kroosec@gmail.com>]

These values aren't used in this case.

Currently, the from field in the request sent by the nbd kernel module leading
to a false error message when ending the connection with the client.

$ qemu-nbd some.img -v
// After nbd-client -d /dev/nbd0
nbd.c:nbd_trip():L1031: From: 18446744073709551104, Len: 0, Size: 20971520,
Offset: 0
nbd.c:nbd_trip():L1032: requested operation past EOF--bad client?
nbd.c:nbd_receive_request():L638: read failed

Signed-off-by: Hani Benhabiles <hani@linux.com>
---
 nbd.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/nbd.c b/nbd.c
index e5084b6..dc076d7 100644
--- a/nbd.c
+++ b/nbd.c
@@ -1001,6 +1001,7 @@ static void nbd_trip(void *opaque)
     struct nbd_request request;
     struct nbd_reply reply;
     ssize_t ret;
+    uint32_t type;
 
     TRACE("Reading request.");
     if (client->closing) {
@@ -1023,8 +1024,8 @@ static void nbd_trip(void *opaque)
         reply.error = -ret;
         goto error_reply;
     }
-
-    if ((request.from + request.len) > exp->size) {
+    type = request.type & NBD_CMD_MASK_COMMAND;
+    if (type != NBD_CMD_DISC && (request.from + request.len) > exp->size) {
             LOG("From: %" PRIu64 ", Len: %u, Size: %" PRIu64
             ", Offset: %" PRIu64 "\n",
                     request.from, request.len,
@@ -1033,7 +1034,7 @@ static void nbd_trip(void *opaque)
         goto invalid_request;
     }
 
-    switch (request.type & NBD_CMD_MASK_COMMAND) {
+    switch (type) {
     case NBD_CMD_READ:
         TRACE("Request type is READ");
 
-- 
1.8.3.2