ext2: 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.
Signed-off-by: Jan Kara <jack@suse.cz>

fs/ext2/dir.c

@@ -81,11 +81,10 @@ ext2_last_byte(struct inode *inode, unsigned long page_nr)
 	return last_byte;
 }
 
-static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
+static void ext2_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);
@@ -94,16 +93,7 @@ static int ext2_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);
-		if (!err)
-			err = sync_inode_metadata(dir, 1);
-	} else {
 	unlock_page(page);
-	}
-
-	return err;
 }
 
 static bool ext2_check_page(struct page *page, int quiet, char *kaddr)
@@ -460,6 +450,17 @@ static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
 	return __block_write_begin(page, pos, len, ext2_get_block);
 }
 
+
+static int ext2_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;
+}
+
 void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
 		   struct page *page, void *page_addr, struct inode *inode,
 		   int update_times)
@@ -474,11 +475,12 @@ void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
 	BUG_ON(err);
 	de->inode = cpu_to_le32(inode->i_ino);
 	ext2_set_de_type(de, inode);
-	err = ext2_commit_chunk(page, pos, len);
+	ext2_commit_chunk(page, pos, len);
 	if (update_times)
 		dir->i_mtime = dir->i_ctime = current_time(dir);
 	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
 	mark_inode_dirty(dir);
+	ext2_handle_dirsync(dir);
 }
 
 /*
@@ -566,10 +568,11 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
 	memcpy(de->name, name, namelen);
 	de->inode = cpu_to_le32(inode->i_ino);
 	ext2_set_de_type (de, inode);
-	err = ext2_commit_chunk(page, pos, rec_len);
+	ext2_commit_chunk(page, pos, rec_len);
 	dir->i_mtime = dir->i_ctime = current_time(dir);
 	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
 	mark_inode_dirty(dir);
+	err = ext2_handle_dirsync(dir);
 	/* OFFSET_CACHE */
 out_put:
 	ext2_put_page(page, page_addr);
@@ -615,10 +618,11 @@ int ext2_delete_entry (struct ext2_dir_entry_2 *dir, struct page *page,
 	if (pde)
 		pde->rec_len = ext2_rec_len_to_disk(to - from);
 	dir->inode = 0;
-	err = ext2_commit_chunk(page, pos, to - from);
+	ext2_commit_chunk(page, pos, to - from);
 	inode->i_ctime = inode->i_mtime = current_time(inode);
 	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
 	mark_inode_dirty(inode);
+	err = ext2_handle_dirsync(inode);
 out:
 	return err;
 }
@@ -658,7 +662,8 @@ int ext2_make_empty(struct inode *inode, struct inode *parent)
 	memcpy (de->name, "..\0", 4);
 	ext2_set_de_type (de, inode);
 	kunmap_atomic(kaddr);
-	err = ext2_commit_chunk(page, 0, chunk_size);
+	ext2_commit_chunk(page, 0, chunk_size);
+	err = ext2_handle_dirsync(inode);
 fail:
 	put_page(page);
 	return err;