[CIFS] Fix hang in find_writable_file

Caused by unneeded reopen during reconnect while spinlock held.

Fixes kernel bugzilla bug #7903

Thanks to Lin Feng Shen for testing this, and Amit Arora for
some nice problem determination to narrow this down.

Acked-by: Dave Kleikamp <shaggy@us.ibm.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/CHANGES b/fs/cifs/CHANGES
index 6d84ca2..bed6215 100644
--- a/fs/cifs/CHANGES
+++ b/fs/cifs/CHANGES
@@ -3,7 +3,10 @@
 Fix NTLMv2 signing. NFS server mounted over cifs works (if cifs mount is
 done with "serverino" mount option).  Add support for POSIX Unlink
 (helps with certain sharing violation cases when server such as
-Samba supports newer POSIX CIFS Protocol Extensions).
+Samba supports newer POSIX CIFS Protocol Extensions). Add "nounix"
+mount option to allow disabling the CIFS Unix Extensions for just
+that mount. Fix hang on spinlock in find_writable_file (race when
+reopening file after session crash).
 
 Version 1.49
 ------------