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@cs.sunysb.edu>

diff --git a/fs/unionfs/debug.c b/fs/unionfs/debug.c
index 424c60d650b4dd3efc5577b5e8d59a6b36861c12..94f0e84c0b0b0477fa34388fd27314484feb145b 100644 (file)
--- 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);