[PATCH] r/o bind mounts: clean up OCFS2 nlink handling

OCFS2 does some operations on i_nlink, then reverts them if some of its
operations fail to complete.  This does not fit in well with the
drop_nlink() logic where we expect i_nlink to stay at zero once it gets
there.

So, delay all of the nlink operations until we're sure that the operations
have completed.  Also, introduce a small helper to check whether an inode
has proper "unlinkable" i_nlink counts no matter whether it is a directory
or regular inode.

This patch is broken out from the others because it does contain some
logical changes.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
Cc: 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>

fs/ocfs2/namei.c

@@ -795,11 +795,23 @@ static int ocfs2_remote_dentry_delete(struct dentry *dentry)
 	return ret;
 }
 
+static inline int inode_is_unlinkable(struct inode *inode)
+{
+	if (S_ISDIR(inode->i_mode)) {
+		if (inode->i_nlink == 2)
+			return 1;
+		return 0;
+	}
+
+	if (inode->i_nlink == 1)
+		return 1;
+	return 0;
+}
+
 static int ocfs2_unlink(struct inode *dir,
 			struct dentry *dentry)
 {
 	int status;
-	unsigned int saved_nlink = 0;
 	struct inode *inode = dentry->d_inode;
 	struct ocfs2_super *osb = OCFS2_SB(dir->i_sb);
 	u64 blkno;
@@ -874,16 +886,6 @@ static int ocfs2_unlink(struct inode *dir,
 		}
 	}
 
-	/* There are still a few steps left until we can consider the
-	 * unlink to have succeeded. Save off nlink here before
-	 * modification so we can set it back in case we hit an issue
-	 * before commit. */
-	saved_nlink = inode->i_nlink;
-	if (S_ISDIR(inode->i_mode))
-		inode->i_nlink = 0;
-	else
-		inode->i_nlink--;
-
 	status = ocfs2_remote_dentry_delete(dentry);
 	if (status < 0) {
 		/* This vote should succeed under all normal
@@ -892,7 +894,7 @@ static int ocfs2_unlink(struct inode *dir,
 		goto leave;
 	}
 
-	if (!inode->i_nlink) {
+	if (inode_is_unlinkable(inode)) {
 		status = ocfs2_prepare_orphan_dir(osb, handle, inode,
 						  orphan_name,
 						  &orphan_entry_bh);
@@ -919,7 +921,7 @@ static int ocfs2_unlink(struct inode *dir,
 
 	fe = (struct ocfs2_dinode *) fe_bh->b_data;
 
-	if (!inode->i_nlink) {
+	if (inode_is_unlinkable(inode)) {
 		status = ocfs2_orphan_add(osb, handle, inode, fe, orphan_name,
 					  orphan_entry_bh);
 		if (status < 0) {
@@ -935,10 +937,10 @@ static int ocfs2_unlink(struct inode *dir,
 		goto leave;
 	}
 
-	/* We can set nlink on the dinode now. clear the saved version
+	if (S_ISDIR(inode->i_mode))
-	 * so that it doesn't get set later. */
+		drop_nlink(inode);
+	drop_nlink(inode);
 	fe->i_links_count = cpu_to_le16(inode->i_nlink);
-	saved_nlink = 0;
 
 	status = ocfs2_journal_dirty(handle, fe_bh);
 	if (status < 0) {
@@ -947,7 +949,7 @@ static int ocfs2_unlink(struct inode *dir,
 	}
 
 	if (S_ISDIR(inode->i_mode)) {
-		dir->i_nlink--;
+		drop_nlink(dir);
 		status = ocfs2_mark_inode_dirty(handle, dir,
 						parent_node_bh);
 		if (status < 0) {
@@ -957,9 +959,6 @@ static int ocfs2_unlink(struct inode *dir,
 	}
 
 leave:
-	if (status < 0 && saved_nlink)
-		inode->i_nlink = saved_nlink;
-
 	if (handle)
 		ocfs2_commit_trans(handle);