[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/udf/namei.c b/fs/udf/namei.c
index ab9a762..d14d255 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -878,8 +878,7 @@
 			inode->i_nlink);
 	inode->i_nlink = 0;
 	inode->i_size = 0;
-	mark_inode_dirty(inode);
-	dir->i_nlink --;
+	inode_dec_link_count(inode);
 	inode->i_ctime = dir->i_ctime = dir->i_mtime = current_fs_time(dir->i_sb);
 	mark_inode_dirty(dir);
 
@@ -923,8 +922,7 @@
 		goto end_unlink;
 	dir->i_ctime = dir->i_mtime = current_fs_time(dir->i_sb);
 	mark_inode_dirty(dir);
-	inode->i_nlink--;
-	mark_inode_dirty(inode);
+	inode_dec_link_count(inode);
 	inode->i_ctime = dir->i_ctime;
 	retval = 0;
 
@@ -1101,8 +1099,7 @@
 	return err;
 
 out_no_entry:
-	inode->i_nlink--;
-	mark_inode_dirty(inode);
+	inode_dec_link_count(inode);
 	iput(inode);
 	goto out;
 }
@@ -1261,9 +1258,8 @@
 
 	if (new_inode)
 	{
-		new_inode->i_nlink--;
 		new_inode->i_ctime = current_fs_time(new_inode->i_sb);
-		mark_inode_dirty(new_inode);
+		inode_dec_link_count(new_inode);
 	}
 	old_dir->i_ctime = old_dir->i_mtime = current_fs_time(old_dir->i_sb);
 	mark_inode_dirty(old_dir);
@@ -1279,12 +1275,10 @@
 		}
 		else
 			mark_buffer_dirty_inode(dir_bh, old_inode);
-		old_dir->i_nlink --;
-		mark_inode_dirty(old_dir);
+		inode_dec_link_count(old_dir);
 		if (new_inode)
 		{
-			new_inode->i_nlink --;
-			mark_inode_dirty(new_inode);
+			inode_dec_link_count(new_inode);
 		}
 		else
 		{