[PATCH v2 1/5] common: move mread() to generic helper _mread()

[Luis Chamberlain <mcgrof@kernel.org>]

We want a shared way to use mmap in a way that we can test
for the SIGBUS, provide a shared routine which other tests can
leverage.

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 common/rc         | 28 ++++++++++++++++++++++++++++
 tests/generic/574 | 36 ++++--------------------------------
 2 files changed, 32 insertions(+), 32 deletions(-)

diff --git a/common/rc b/common/rc
index 163041fea5b9..fa7942809d6c 100644
--- a/common/rc
+++ b/common/rc
@@ -52,6 +52,34 @@ _pwrite_byte() {
 	$XFS_IO_PROG $xfs_io_args -f -c "pwrite -S $pattern $offset $len" "$file"
 }
 
+_round_up_to_page_boundary()
+{
+	local n=$1
+	local page_size=$(_get_page_size)
+
+	echo $(( (n + page_size - 1) & ~(page_size - 1) ))
+}
+
+_mread()
+{
+	local file=$1
+	local offset=$2
+	local length=$3
+	local map_len=$(_round_up_to_page_boundary $(_get_filesize $file))
+
+	# Some callers expect xfs_io to crash with SIGBUS due to the mread,
+	# causing the shell to print "Bus error" to stderr.  To allow this
+	# message to be redirected, execute xfs_io in a new shell instance.
+	# However, for this to work reliably, we also need to prevent the new
+	# shell instance from optimizing out the fork and directly exec'ing
+	# xfs_io.  The easiest way to do that is to append 'true' to the
+	# commands, so that xfs_io is no longer the last command the shell sees.
+	# Don't let it write core files to the filesystem.
+	bash -c "trap '' SIGBUS; ulimit -c 0; $XFS_IO_PROG -r $file \
+		-c 'mmap -r 0 $map_len' \
+		-c 'mread -v $offset $length'; true"
+}
+
 # mmap-write a byte into a range of a file
 _mwrite_byte() {
 	local pattern="$1"
diff --git a/tests/generic/574 b/tests/generic/574
index cb42baaa67aa..d44c23e5abc2 100755
--- a/tests/generic/574
+++ b/tests/generic/574
@@ -52,34 +52,6 @@ setup_zeroed_file()
 	cmp $fsv_orig_file $fsv_file
 }
 
-round_up_to_page_boundary()
-{
-	local n=$1
-	local page_size=$(_get_page_size)
-
-	echo $(( (n + page_size - 1) & ~(page_size - 1) ))
-}
-
-mread()
-{
-	local file=$1
-	local offset=$2
-	local length=$3
-	local map_len=$(round_up_to_page_boundary $(_get_filesize $file))
-
-	# Some callers expect xfs_io to crash with SIGBUS due to the mread,
-	# causing the shell to print "Bus error" to stderr.  To allow this
-	# message to be redirected, execute xfs_io in a new shell instance.
-	# However, for this to work reliably, we also need to prevent the new
-	# shell instance from optimizing out the fork and directly exec'ing
-	# xfs_io.  The easiest way to do that is to append 'true' to the
-	# commands, so that xfs_io is no longer the last command the shell sees.
-	# Don't let it write core files to the filesystem.
-	bash -c "trap '' SIGBUS; ulimit -c 0; $XFS_IO_PROG -r $file \
-		-c 'mmap -r 0 $map_len' \
-		-c 'mread -v $offset $length'; true"
-}
-
 corruption_test()
 {
 	local block_size=$1
@@ -142,7 +114,7 @@ corruption_test()
 	fi
 
 	# Reading the full file via mmap should fail.
-	mread $fsv_file 0 $file_len >/dev/null 2>$tmp.err
+	_mread $fsv_file 0 $file_len >/dev/null 2>$tmp.err
 	if ! grep -q 'Bus error' $tmp.err; then
 		echo "Didn't see SIGBUS when reading file via mmap"
 		cat $tmp.err
@@ -150,7 +122,7 @@ corruption_test()
 
 	# Reading just the corrupted part via mmap should fail.
 	if ! $is_merkle_tree; then
-		mread $fsv_file $zap_offset $zap_len >/dev/null 2>$tmp.err
+		_mread $fsv_file $zap_offset $zap_len >/dev/null 2>$tmp.err
 		if ! grep -q 'Bus error' $tmp.err; then
 			echo "Didn't see SIGBUS when reading corrupted part via mmap"
 			cat $tmp.err
@@ -174,10 +146,10 @@ corrupt_eof_block_test()
 	head -c $zap_len /dev/zero | tr '\0' X \
 		| _fsv_scratch_corrupt_bytes $fsv_file $file_len
 
-	mread $fsv_file $file_len $zap_len >$tmp.out 2>$tmp.err
+	_mread $fsv_file $file_len $zap_len >$tmp.out 2>$tmp.err
 
 	head -c $file_len /dev/zero >$tmp.zeroes
-	mread $tmp.zeroes $file_len $zap_len >$tmp.zeroes_out
+	_mread $tmp.zeroes $file_len $zap_len >$tmp.zeroes_out
 
 	grep -q 'Bus error' $tmp.err || diff $tmp.out $tmp.zeroes_out
 }
-- 
2.43.0