ufs: don't flush page immediately for DIRSYNC directories

We do not need to writeout modified directory blocks immediately when
modifying them while the page is locked. It is enough to do the flush
somewhat later which has the added benefit that inode times can be
flushed as well. It also allows us to stop depending on
write_one_page() function.

Ported from an ext2 patch by Jan Kara.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ufs/dir.c

@@ -42,11 +42,10 @@ static inline int ufs_match(struct super_block *sb, int len,
 	return !memcmp(name, de->d_name, len);
 }
 
-static int ufs_commit_chunk(struct page *page, loff_t pos, unsigned len)
+static void ufs_commit_chunk(struct page *page, loff_t pos, unsigned len)
 {
 	struct address_space *mapping = page->mapping;
 	struct inode *dir = mapping->host;
-	int err = 0;
 
 	inode_inc_iversion(dir);
 	block_write_end(NULL, mapping, pos, len, len, page, NULL);
@@ -54,10 +53,16 @@ static int ufs_commit_chunk(struct page *page, loff_t pos, unsigned len)
 		i_size_write(dir, pos+len);
 		mark_inode_dirty(dir);
 	}
-	if (IS_DIRSYNC(dir))
-		err = write_one_page(page);
-	else
-		unlock_page(page);
+	unlock_page(page);
+}
+
+static int ufs_handle_dirsync(struct inode *dir)
+{
+	int err;
+
+	err = filemap_write_and_wait(dir->i_mapping);
+	if (!err)
+		err = sync_inode_metadata(dir, 1);
 	return err;
 }
 
@@ -99,11 +104,12 @@ void ufs_set_link(struct inode *dir, struct ufs_dir_entry *de,
 	de->d_ino = cpu_to_fs32(dir->i_sb, inode->i_ino);
 	ufs_set_de_type(dir->i_sb, de, inode->i_mode);
 
-	err = ufs_commit_chunk(page, pos, len);
+	ufs_commit_chunk(page, pos, len);
 	ufs_put_page(page);
 	if (update_times)
 		dir->i_mtime = dir->i_ctime = current_time(dir);
 	mark_inode_dirty(dir);
+	ufs_handle_dirsync(dir);
 }
 
 
@@ -390,10 +396,11 @@ int ufs_add_link(struct dentry *dentry, struct inode *inode)
 	de->d_ino = cpu_to_fs32(sb, inode->i_ino);
 	ufs_set_de_type(sb, de, inode->i_mode);
 
-	err = ufs_commit_chunk(page, pos, rec_len);
+	ufs_commit_chunk(page, pos, rec_len);
 	dir->i_mtime = dir->i_ctime = current_time(dir);
 
 	mark_inode_dirty(dir);
+	err = ufs_handle_dirsync(dir);
 	/* OFFSET_CACHE */
 out_put:
 	ufs_put_page(page);
@@ -531,9 +538,10 @@ int ufs_delete_entry(struct inode *inode, struct ufs_dir_entry *dir,
 	if (pde)
 		pde->d_reclen = cpu_to_fs16(sb, to - from);
 	dir->d_ino = 0;
-	err = ufs_commit_chunk(page, pos, to - from);
+	ufs_commit_chunk(page, pos, to - from);
 	inode->i_ctime = inode->i_mtime = current_time(inode);
 	mark_inode_dirty(inode);
+	err = ufs_handle_dirsync(inode);
 out:
 	ufs_put_page(page);
 	UFSD("EXIT\n");
@@ -579,7 +587,8 @@ int ufs_make_empty(struct inode * inode, struct inode *dir)
 	strcpy (de->d_name, "..");
 	kunmap(page);
 
-	err = ufs_commit_chunk(page, 0, chunk_size);
+	ufs_commit_chunk(page, 0, chunk_size);
+	err = ufs_handle_dirsync(inode);
 fail:
 	put_page(page);
 	return err;