[PATCH 08/15] jbd: replace barriers with explicit flush / FUA usage

[Christoph Hellwig <hch@infradead.org>]

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Switch to the WRITE_FLUSH_FUA flag for journal commits and remove the
EOPNOTSUPP detection for barriers.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: linux-2.6/fs/jbd/commit.c
===================================================================
--- linux-2.6.orig/fs/jbd/commit.c	2010-08-17 16:46:44.370004211 +0200
+++ linux-2.6/fs/jbd/commit.c	2010-08-17 16:47:18.894004770 +0200
@@ -137,34 +137,10 @@ static int journal_write_commit_record(j
 	JBUFFER_TRACE(descriptor, "write commit block");
 	set_buffer_dirty(bh);
 
-	if (journal->j_flags & JFS_BARRIER) {
-		ret = __sync_dirty_buffer(bh, WRITE_SYNC | WRITE_BARRIER);
-
-		/*
-		 * Is it possible for another commit to fail at roughly
-		 * the same time as this one?  If so, we don't want to
-		 * trust the barrier flag in the super, but instead want
-		 * to remember if we sent a barrier request
-		 */
-		if (ret == -EOPNOTSUPP) {
-			char b[BDEVNAME_SIZE];
-
-			printk(KERN_WARNING
-				"JBD: barrier-based sync failed on %s - "
-				"disabling barriers\n",
-				bdevname(journal->j_dev, b));
-			spin_lock(&journal->j_state_lock);
-			journal->j_flags &= ~JFS_BARRIER;
-			spin_unlock(&journal->j_state_lock);
-
-			/* And try again, without the barrier */
-			set_buffer_uptodate(bh);
-			set_buffer_dirty(bh);
-			ret = sync_dirty_buffer(bh);
-		}
-	} else {
+	if (journal->j_flags & JFS_BARRIER)
+		ret = __sync_dirty_buffer(bh, WRITE_SYNC | WRITE_FLUSH_FUA);
+	else
 		ret = sync_dirty_buffer(bh);
-	}
 
 	put_bh(bh);		/* One for getblk() */
 	journal_put_journal_head(descriptor);