linux-kernel - [PATCH] Btrfs: fix filemap_flush call in btrfs_file

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Message-ID: <53F4B555.7060403@fb.com>
Date:	Wed, 20 Aug 2014 10:48:53 -0400
From:	Chris Mason <clm@...com>
To:	<miaox@...fujitsu.com>, <dsterba@...e.cz>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Dave Hansen <dave.hansen@...el.com>,
	LKML <linux-kernel@...r.kernel.org>, <lkp@...org>,
	"linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>,
	Abhay Sachan <lkp.abhay@...il.com>
Subject: [PATCH] Btrfs: fix filemap_flush call in btrfs_file_release


We should only be flushing on close if the file was flagged as needing
it during truncate.  I broke this with my ordered data vs transaction
commit deadlock fix.

Thanks to Miao Xie for catching this.

Signed-off-by: Chris Mason <clm@...com>
Reported-by: Miao Xie <miaox@...fujitsu.com>
Reported-by: Fengguang Wu <fengguang.wu@...el.com>

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index f15c13f..36861b7 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1840,7 +1840,15 @@ int btrfs_release_file(struct inode *inode, struct file *filp)
 {
 	if (filp->private_data)
 		btrfs_ioctl_trans_end(filp);
-	filemap_flush(inode->i_mapping);
+	/*
+	 * ordered_data_close is set by settattr when we are about to truncate
+	 * a file from a non-zero size to a zero size.  This tries to
+	 * flush down new bytes that may have been written if the
+	 * application were using truncate to replace a file in place.
+	 */
+	if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
+			       &BTRFS_I(inode)->runtime_flags))
+			filemap_flush(inode->i_mapping);
 	return 0;
 }
 
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