linux-kernel - [PATCH 3/5] ext4: call blkdev_issue

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Date:	Mon, 30 Mar 2009 10:43:45 +0900
From:	Fernando Luis Vázquez Cao 
	<fernando@....ntt.co.jp>
To:	Christoph Hellwig <hch@...radead.org>
CC:	Jeff Garzik <jeff@...zik.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Theodore Tso <tytso@....edu>, Ingo Molnar <mingo@...e.hu>,
	Alan Cox <alan@...rguk.ukuu.org.uk>,
	Arjan van de Ven <arjan@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Nick Piggin <npiggin@...e.de>, David Rees <drees76@...il.com>,
	Jesper Krogh <jesper@...gh.cc>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 3/5] ext4: call blkdev_issue_flush on fsync

To ensure that bits are truly on-disk after an fsync or fdatasync, we
should force a disk flush explicitly when there is dirty data/metadata
and the journal didn't emit a write barrier (either because metadata is
not being synched or barriers are disabled).

Signed-off-by: Fernando Luis Vazquez Cao <fernando@....ntt.co.jp>
---

diff -urNp linux-2.6.29-orig/fs/ext4/fsync.c linux-2.6.29/fs/ext4/fsync.c
--- linux-2.6.29-orig/fs/ext4/fsync.c	2009-03-24 08:12:14.000000000 +0900
+++ linux-2.6.29/fs/ext4/fsync.c	2009-03-28 20:48:17.000000000 +0900
@@ -48,6 +48,7 @@ int ext4_sync_file(struct file *file, st
  {
  	struct inode *inode = dentry->d_inode;
  	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
+	unsigned long i_state = inode->i_state;
  	int ret = 0;

  	J_ASSERT(ext4_journal_current_handle() == NULL);
@@ -76,25 +77,30 @@ int ext4_sync_file(struct file *file, st
  	 */
  	if (ext4_should_journal_data(inode)) {
  		ret = ext4_force_commit(inode->i_sb);
-		goto out;
+		if (!(journal->j_flags & JBD2_BARRIER))
+			block_flush_device(inode->i_sb);
+		return ret;
  	}

-	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
-		goto out;
+	if (datasync && !(i_state & I_DIRTY_DATASYNC)) {
+		if (i_state & I_DIRTY_PAGES)
+			block_flush_device(inode->i_sb);
+		return ret;
+	}

  	/*
  	 * The VFS has written the file data.  If the inode is unaltered
  	 * then we need not start a commit.
  	 */
-	if (inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC)) {
+	if (i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC)) {
  		struct writeback_control wbc = {
  			.sync_mode = WB_SYNC_ALL,
  			.nr_to_write = 0, /* sys_fsync did this */
  		};
  		ret = sync_inode(inode, &wbc);
-		if (journal && (journal->j_flags & JBD2_BARRIER))
-			blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
+		if (journal && !(journal->j_flags & JBD2_BARRIER))
+			block_flush_device(inode->i_sb);
  	}
-out:
+
  	return ret;
  }
--
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