GIT: unionfs2-2.6.27.y: Unionfs: debugging: don't oops if sb->s_root is NULL

[Erez Zadok]

commit aa7c42e134520bb2f1c0290b10c40b8d0bbf2819
Author: Erez_Zadok <ezk at cs.sunysb.edu>
Date:   Mon Jul 16 23:40:07 2007 -0400

    Unionfs: debugging: don't oops if sb->s_root is NULL
    
    If we're calling show_branch_counts very early during mount or late during
    unmount, don't oops if the s_root is already NULL.
    
    Signed-off-by: Erez Zadok <ezk at cs.sunysb.edu>

diff --git a/fs/unionfs/debug.c b/fs/unionfs/debug.c
index 424c60d..94f0e84 100644
--- a/fs/unionfs/debug.c
+++ b/fs/unionfs/debug.c
@@ -416,7 +416,10 @@ void __show_branch_counts(const struct super_block *sb,
 
 	printk("BC:");
 	for (i=0; i<sbmax(sb); i++) {
-		mnt = UNIONFS_D(sb->s_root)->lower_paths[i].mnt;
+		if (sb->s_root)
+			mnt = UNIONFS_D(sb->s_root)->lower_paths[i].mnt;
+		else
+			mnt = NULL;
 		printk("%d:", (mnt ? atomic_read(&mnt->mnt_count) : -99));
 	}
 	printk("%s:%s:%d\n",file,fxn,line);