[CIFS] DNS name resolution helper upcall for cifs

	Adds additional option CIFS_DFS_UPCALL to fs/Kconfig for enabling
        DFS support.  Resolved IP address is saved as a string in the
	key payload.

	Igor has a series of related patches that will follow which finish up
	CIFS DFS support

Acked-by: Igor Mammedov <niallain@gmail.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

2 files changed, 16 insertions, 1 deletions

diff --git a/fs/cifs/Makefile b/fs/cifs/Makefile
index 45e42fb97c19..09898b8dc69b 100644
--- a/fs/cifs/Makefile
+++ b/fs/cifs/Makefile
@@ -9,3 +9,5 @@ cifs-y := cifsfs.o cifssmb.o cifs_debug.o connect.o dir.o file.o inode.o \
           readdir.o ioctl.o sess.o export.o cifsacl.o
 
 cifs-$(CONFIG_CIFS_UPCALL) += cifs_spnego.o
+
+cifs-$(CONFIG_CIFS_DFS_UPCALL) += dns_resolve.o
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 093beaa3900d..000b4a5d3219 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -44,6 +44,7 @@
 #include "cifs_fs_sb.h"
 #include <linux/mm.h>
 #include <linux/key-type.h>
+#include "dns_resolve.h"
 #include "cifs_spnego.h"
 #define CIFS_MAGIC_NUMBER 0xFF534D42    /* the first four bytes of SMB PDUs */
 
@@ -1015,11 +1016,16 @@ init_cifs(void)
         if (rc)
                 goto out_unregister_filesystem;
 #endif
+#ifdef CONFIG_CIFS_DFS_UPCALL
+        rc = register_key_type(&key_type_dns_resolver);
+        if (rc)
+                goto out_unregister_key_type;
+#endif
         oplockThread = kthread_run(cifs_oplock_thread, NULL, "cifsoplockd");
         if (IS_ERR(oplockThread)) {
                 rc = PTR_ERR(oplockThread);
                 cERROR(1, ("error %d create oplock thread", rc));
-                goto out_unregister_key_type;
+                goto out_unregister_dfs_key_type;
         }
 
         dnotifyThread = kthread_run(cifs_dnotify_thread, NULL, "cifsdnotifyd");
@@ -1033,7 +1039,11 @@ init_cifs(void)
 
  out_stop_oplock_thread:
         kthread_stop(oplockThread);
+ out_unregister_dfs_key_type:
+#ifdef CONFIG_CIFS_DFS_UPCALL
+        unregister_key_type(&key_type_dns_resolver);
  out_unregister_key_type:
+#endif
 #ifdef CONFIG_CIFS_UPCALL
         unregister_key_type(&cifs_spnego_key_type);
  out_unregister_filesystem:
@@ -1059,6 +1069,9 @@ exit_cifs(void)
 #ifdef CONFIG_PROC_FS
         cifs_proc_clean();
 #endif
+#ifdef CONFIG_CIFS_DFS_UPCALL
+        unregister_key_type(&key_type_dns_resolver);
+#endif
 #ifdef CONFIG_CIFS_UPCALL
         unregister_key_type(&cifs_spnego_key_type);
 #endif