From f8009d2223fb8acc068eed92c4ca8d3e159ad77b Mon Sep 17 00:00:00 2001
From: Azat Khuzhin <a3at.mail@gmail.com>
Date: Sun, 13 Jul 2014 00:44:35 +0400
Subject: [PATCH] simplefs_write: add journaling using jbd2

---
 simple.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/simple.c b/simple.c
index 7b1e2a8..2c64d53 100644
--- a/simple.c
+++ b/simple.c
@@ -359,19 +359,25 @@ ssize_t simplefs_write(struct file * filp, const char __user * buf, size_t len,
 	struct simplefs_inode *sfs_inode;
 	struct buffer_head *bh;
 	struct super_block *sb;
+	struct simplefs_super_block *sfs_sb;
+	handle_t *handle;
 
 	char *buffer;
 
 	int retval;
 
+	sb = filp->f_path.dentry->d_inode->i_sb;
+	sfs_sb = SIMPLEFS_SB(sb);
+
+	handle = jbd2_journal_start(sfs_sb->journal, 1);
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
 	retval = generic_write_checks(filp, ppos, &len, 0);
-	if (retval) {
+	if (retval)
 		return retval;
-	}
 
 	inode = filp->f_path.dentry->d_inode;
 	sfs_inode = SIMPLEFS_INODE(inode);
-	sb = inode->i_sb;
 
 	bh = sb_bread(filp->f_path.dentry->d_inode->i_sb,
 					    sfs_inode->data_block_number);
@@ -386,6 +392,13 @@ ssize_t simplefs_write(struct file * filp, const char __user * buf, size_t len,
 	/* Move the pointer until the required byte offset */
 	buffer += *ppos;
 
+	retval = jbd2_journal_get_write_access(handle, bh);
+	if (WARN_ON(retval)) {
+		brelse(bh);
+		sfs_trace("Can't get write access for bh\n");
+		return retval;
+	}
+
 	if (copy_from_user(buffer, buf, len)) {
 		brelse(bh);
 		printk(KERN_ERR
@@ -394,6 +407,17 @@ ssize_t simplefs_write(struct file * filp, const char __user * buf, size_t len,
 	}
 	*ppos += len;
 
+	retval = jbd2_journal_dirty_metadata(handle, bh);
+	if (WARN_ON(retval)) {
+		brelse(bh);
+		return retval;
+	}
+	retval = jbd2_journal_stop(handle);
+	if (WARN_ON(retval)) {
+		brelse(bh);
+		return retval;
+	}
+
 	mark_buffer_dirty(bh);
 	sync_dirty_buffer(bh);
 	brelse(bh);