linux-ext4 - [PATCH] jbd2: finish inode data buffers immediately after submiting data buffers

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Date:	Fri, 7 Nov 2014 15:06:15 +0800
From:	alex chen <alex.chen@...wei.com>
To:	<tytso@....edu>
CC:	<linux-ext4@...r.kernel.org>, Jan Kara <jack@...e.cz>,
	Joseph Qi <joseph.qi@...wei.com>,
	<linux-fsdevel@...r.kernel.org>
Subject: [PATCH] jbd2: finish inode data buffers immediately after submiting
 data buffers

During commit process, journal_finish_inode_data_buffers will flush plug
list as follow:
jbd2_journal_commit_transaction
->journal_finish_inode_data_buffers
->filemap_fdatawait_range
->wait_on_page_bit
->__wait_on_bit
->sleep_on_page
->io_schedule
->blk_flush_plug_list

When ASYNC_COMMIT feature is set, the journal_finish_inode_data_buffers
separates the commit blocks from the rest of the journal blocks. So we
should finish inode data buffers immediately after submiting data
buffers, this allow most of the journal blocks to be written in a single
I/O operation and improve journal commit performance.

Signed-off-by: Alex Chen <alex.chen@...wei.com>
---
 fs/jbd2/commit.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index b73e021..dc33d89 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -555,6 +555,16 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	if (err)
 		jbd2_journal_abort(journal, err);

+	err = journal_finish_inode_data_buffers(journal, commit_transaction);
+	if (err) {
+		printk(KERN_WARNING
+			"JBD2: Detected IO errors while flushing file data "
+		       "on %s\n", journal->j_devname);
+		if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
+			jbd2_journal_abort(journal, err);
+		err = 0;
+	}
+
 	blk_start_plug(&plug);
 	jbd2_journal_write_revoke_records(journal, commit_transaction,
 					  &log_bufs, WRITE_SYNC);
@@ -752,16 +762,6 @@ start_journal_io:
 		}
 	}

-	err = journal_finish_inode_data_buffers(journal, commit_transaction);
-	if (err) {
-		printk(KERN_WARNING
-			"JBD2: Detected IO errors while flushing file data "
-		       "on %s\n", journal->j_devname);
-		if (journal->j_flags & JBD2_ABORT_ON_SYNCDATA_ERR)
-			jbd2_journal_abort(journal, err);
-		err = 0;
-	}
-
 	/*
 	 * Get current oldest transaction in the log before we issue flush
 	 * to the filesystem device. After the flush we can be sure that
-- 
1.8.4.3
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