[PATCH 4/6] sysv: don't flush page immediately for DIRSYNC directories

[Christoph Hellwig <hch@xxxxxx>]

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@xxxxxx>
---
 fs/sysv/dir.c | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/fs/sysv/dir.c b/fs/sysv/dir.c
index 88e38cd8f5c9ae..16730795a62161 100644
--- a/fs/sysv/dir.c
+++ b/fs/sysv/dir.c
@@ -34,21 +34,26 @@ static inline void dir_put_page(struct page *page)
 	put_page(page);
 }
 
-static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
+static void dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
 {
 	struct address_space *mapping = page->mapping;
 	struct inode *dir = mapping->host;
-	int err = 0;
 
 	block_write_end(NULL, mapping, pos, len, len, page, NULL);
 	if (pos+len > dir->i_size) {
 		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 sysv_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;
 }
 
@@ -215,9 +220,10 @@ int sysv_add_link(struct dentry *dentry, struct inode *inode)
 	memcpy (de->name, name, namelen);
 	memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
 	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
-	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
+	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
 	dir->i_mtime = dir->i_ctime = current_time(dir);
 	mark_inode_dirty(dir);
+	err = sysv_handle_dirsync(dir);
 out_page:
 	dir_put_page(page);
 out:
@@ -238,11 +244,11 @@ int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
 	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
 	BUG_ON(err);
 	de->inode = 0;
-	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
+	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
 	dir_put_page(page);
 	inode->i_ctime = inode->i_mtime = current_time(inode);
 	mark_inode_dirty(inode);
-	return err;
+	return sysv_handle_dirsync(inode);
 }
 
 int sysv_make_empty(struct inode *inode, struct inode *dir)
@@ -272,7 +278,8 @@ int sysv_make_empty(struct inode *inode, struct inode *dir)
 	strcpy(de->name,"..");
 
 	kunmap(page);
-	err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
+	dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
+	err = sysv_handle_dirsync(inode);
 fail:
 	put_page(page);
 	return err;
@@ -336,10 +343,11 @@ void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
 	err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE);
 	BUG_ON(err);
 	de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
-	err = dir_commit_chunk(page, pos, SYSV_DIRSIZE);
+	dir_commit_chunk(page, pos, SYSV_DIRSIZE);
 	dir_put_page(page);
 	dir->i_mtime = dir->i_ctime = current_time(dir);
 	mark_inode_dirty(dir);
+	sysv_handle_dirsync(inode);
 }
 
 struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
-- 
2.39.0