fuse: decrement nlink on overwriting rename

Rename didn't decrement/clear nlink on overwritten target inode.

Create a common helper fuse_entry_unlinked() that handles this for unlink,
rmdir and rename.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/dir.c

@@ -755,6 +755,29 @@ void fuse_update_ctime(struct inode *inode)
 	}
 }
 
+static void fuse_entry_unlinked(struct dentry *entry)
+{
+	struct inode *inode = d_inode(entry);
+	struct fuse_conn *fc = get_fuse_conn(inode);
+	struct fuse_inode *fi = get_fuse_inode(inode);
+
+	spin_lock(&fi->lock);
+	fi->attr_version = atomic64_inc_return(&fc->attr_version);
+	/*
+	 * If i_nlink == 0 then unlink doesn't make sense, yet this can
+	 * happen if userspace filesystem is careless.  It would be
+	 * difficult to enforce correct nlink usage so just ignore this
+	 * condition here
+	 */
+	if (S_ISDIR(inode->i_mode))
+		clear_nlink(inode);
+	else if (inode->i_nlink > 0)
+		drop_nlink(inode);
+	spin_unlock(&fi->lock);
+	fuse_invalidate_entry_cache(entry);
+	fuse_update_ctime(inode);
+}
+
 static int fuse_unlink(struct inode *dir, struct dentry *entry)
 {
 	int err;
@@ -771,23 +794,8 @@ static int fuse_unlink(struct inode *dir, struct dentry *entry)
 	args.in_args[0].value = entry->d_name.name;
 	err = fuse_simple_request(fm, &args);
 	if (!err) {
-		struct inode *inode = d_inode(entry);
-		struct fuse_inode *fi = get_fuse_inode(inode);
-
-		spin_lock(&fi->lock);
-		fi->attr_version = atomic64_inc_return(&fm->fc->attr_version);
-		/*
-		 * If i_nlink == 0 then unlink doesn't make sense, yet this can
-		 * happen if userspace filesystem is careless.  It would be
-		 * difficult to enforce correct nlink usage so just ignore this
-		 * condition here
-		 */
-		if (inode->i_nlink > 0)
-			drop_nlink(inode);
-		spin_unlock(&fi->lock);
 		fuse_dir_changed(dir);
-		fuse_invalidate_entry_cache(entry);
-		fuse_update_ctime(inode);
+		fuse_entry_unlinked(entry);
 	} else if (err == -EINTR)
 		fuse_invalidate_entry(entry);
 	return err;
@@ -809,9 +817,8 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
 	args.in_args[0].value = entry->d_name.name;
 	err = fuse_simple_request(fm, &args);
 	if (!err) {
-		clear_nlink(d_inode(entry));
 		fuse_dir_changed(dir);
-		fuse_invalidate_entry_cache(entry);
+		fuse_entry_unlinked(entry);
 	} else if (err == -EINTR)
 		fuse_invalidate_entry(entry);
 	return err;
@@ -851,10 +858,8 @@ static int fuse_rename_common(struct inode *olddir, struct dentry *oldent,
 			fuse_dir_changed(newdir);
 
 		/* newent will end up negative */
-		if (!(flags & RENAME_EXCHANGE) && d_really_is_positive(newent)) {
-			fuse_invalidate_entry_cache(newent);
-			fuse_update_ctime(d_inode(newent));
-		}
+		if (!(flags & RENAME_EXCHANGE) && d_really_is_positive(newent))
+			fuse_entry_unlinked(newent);
 	} else if (err == -EINTR) {
 		/* If request was interrupted, DEITY only knows if the
 		   rename actually took place.  If the invalidation