From 409c6118d39cb2d8666bee3d61a1a9ae5bbd4f5d Mon Sep 17 00:00:00 2001
From: Chris Mason <chris.mason@oracle.com>
Date: Tue, 22 Apr 2008 09:24:20 -0400
Subject: [PATCH] Btrfs: Set nodatasum on the inode when written by a nodatasum
 mount

Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
 fs/btrfs/file.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 3f5525f0834c..5d537f26dc83 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -863,6 +863,14 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
 	first_index = pos >> PAGE_CACHE_SHIFT;
 	last_index = (pos + count) >> PAGE_CACHE_SHIFT;
 
+	/*
+	 * if this is a nodatasum mount, force summing off for the inode
+	 * all the time.  That way a later mount with summing on won't
+	 * get confused
+	 */
+	if (btrfs_test_opt(root, NODATASUM))
+		btrfs_set_flag(inode, NODATASUM);
+
 	/*
 	 * there are lots of better ways to do this, but this code
 	 * makes sure the first and last page in the file range are
-- 
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