[PATCH] r/o bind mounts: unlink: monitor i_nlink

When a filesystem decrements i_nlink to zero, it means that a write must be
performed in order to drop the inode from the filesystem.

We're shortly going to have keep filesystems from being remounted r/o between
the time that this i_nlink decrement and that write occurs.

So, add a little helper function to do the decrements.  We'll tie into it in a
bit to note when i_nlink hits zero.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/hpfs/namei.c b/fs/hpfs/namei.c
index 59e7dc1..4078b0b 100644
--- a/fs/hpfs/namei.c
+++ b/fs/hpfs/namei.c
@@ -434,7 +434,7 @@
 		unlock_kernel();
 		return -ENOSPC;
 	default:
-		inode->i_nlink--;
+		drop_nlink(inode);
 		err = 0;
 	}
 	goto out;
@@ -494,7 +494,7 @@
 		err = -ENOSPC;
 		break;
 	default:
-		dir->i_nlink--;
+		drop_nlink(dir);
 		inode->i_nlink = 0;
 		err = 0;
 	}
@@ -636,7 +636,7 @@
 	hpfs_i(i)->i_parent_dir = new_dir->i_ino;
 	if (S_ISDIR(i->i_mode)) {
 		new_dir->i_nlink++;
-		old_dir->i_nlink--;
+		drop_nlink(old_dir);
 	}
 	if ((fnode = hpfs_map_fnode(i->i_sb, i->i_ino, &bh))) {
 		fnode->up = new_dir->i_ino;