From patchwork Fri Mar  4 01:51:55 2011
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From: Chris Mason <chris.mason@oracle.com>
To: "Zhong, Xin" <xin.zhong@intel.com>
Cc: Mitch Harder <mitch.harder@sabayonlinux.org>,
	Xin Zhong <thierryzhong@hotmail.com>,
	"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: RE: [PATCH] btrfs file write debugging patch
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Date: Thu, 03 Mar 2011 20:51:55 -0500
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diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 89a6a26..6a44add 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1039,6 +1038,14 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
 
 		copied = btrfs_copy_from_user(pos, num_pages,
 					   write_bytes, pages, &i);
+
+		/*
+		 * if we have trouble faulting in the pages, fall
+		 * back to one page at a time
+		 */
+		if (copied < write_bytes)
+			nrptrs = 1;
+
 		if (copied == 0)
 			dirty_pages = 0;
 		else