From ae11d3088dd73df1000855102ef90177d102dd52 Mon Sep 17 00:00:00 2001
From: Dave Chinner <david@fromorbit.com>
Date: Tue, 25 Oct 2016 09:52:21 +1100
Subject: [PATCH] libxfs_apply: filterdiff can't handle /dev/null properly

Because we are mangling the diff source/destination locations, we
have to add prefixes to them to get them to apply cleanly as -p1
patches. This is all fine until we create or remove a file and
the the src/dest is /dev/null. Applying a prefix here causes
the diff to be malformed and it won't apply.

Add another hack to work around this limitation of filterdiff when
reformatting the diff into readable format.

Signed-off-by: Dave Chinner <david@fromorbit.com>
---
 tools/libxfs-apply | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/tools/libxfs-apply b/tools/libxfs-apply
index 50f628a03..8df1a49dc 100755
--- a/tools/libxfs-apply
+++ b/tools/libxfs-apply
@@ -140,13 +140,18 @@ filter_kernel_patch()
 	ls -1 fs/xfs/libxfs/*.[ch] | sed -e "s%.*/\(.*\)%*\1%" > $_libxfs_files
 
 	# Create the new patch
+	# filterdiff will have screwed up files that source/sink /dev/null.
+	# fix that up with some sed magic.
 	filterdiff \
-		--verbose \
-		-I $_libxfs_files \
-		--strip=1 \
-		--addoldprefix=a/fs/xfs/ \
-		--addnewprefix=b/fs/xfs/ \
-		$_patch
+			--verbose \
+			-I $_libxfs_files \
+			--strip=1 \
+			--addoldprefix=a/fs/xfs/ \
+			--addnewprefix=b/fs/xfs/ \
+			$_patch | \
+		sed -e 's, [ab]\/fs\/xfs\/\(\/dev\/null\), \1,' \
+		    -e '/^diff --git/d'
+
 
 	rm -f $_libxfs_files
 }
@@ -164,13 +169,17 @@ filter_xfsprogs_patch()
 	lsdiff $_patch | sed -e "s%.*/\(.*\)%*libxfs/\1%" > $_libxfs_files
 
 	# Create the new patch
+	# filterdiff will have screwed up files that source/sink /dev/null.
+	# fix that up with some sed magic.
 	filterdiff \
-		--verbose \
-		-I $_libxfs_files \
-		--strip=3 \
-		--addoldprefix=a/ \
-		--addnewprefix=b/ \
-		$_patch
+			--verbose \
+			-I $_libxfs_files \
+			--strip=3 \
+			--addoldprefix=a/ \
+			--addnewprefix=b/ \
+			$_patch | \
+		sed -e 's, [ab]\/\(\/dev\/null\), \1,' \
+		    -e '/^diff --git/d'
 
 	rm -f $_libxfs_files
 }
-- 
2.47.2