[CIFS] ACPI suspend oops

Wasn't able to reproduce a hard hang, but was able to get an oops if
suspended the machine during a copy to the cifs mount.  This led to some
things hanging, including a "sync".  Also got I/O errors when trying to
access the mount afterwards (even when didn't see the oops), and had
to unmount and remount in order to access the filesystem.

This patch fixed the oops.

Signed-off-by: Dave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 7ef30efe8f98..c881a1a29f0b 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -904,8 +904,10 @@ static ssize_t cifs_write(struct file *file, const char *write_data,
                                 if (rc != 0)
                                         break;
                         }
-                        if(experimEnabled || (pTcon->ses->server->secMode & 
-                         (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)) == 0) {
+                        if(experimEnabled || (pTcon->ses->server &&
+                                (pTcon->ses->server->secMode & 
+                                (SECMODE_SIGN_REQUIRED | SECMODE_SIGN_ENABLED)
+                                == 0))) {
                                 struct kvec iov[2];
                                 unsigned int len;