xfstests generic 308: test write to the last block of max file size on ext4

On unpatched ext4 if an extent exists which includes the block right
before the maximum file offset, and the block for the maximum file
offset is written, the kernel panics.

On patched ext4, the write would get EFBIG since we lower s_maxbytes
by one fs block.

Regression test for commit:
f17722f ext4: Fix max file size and logical block counting of extent format file

Though it's an ext4 specific issue, it's no harm to run on all file
systems, so put it in generic.

Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Rich Johnston <rjohnston@sgi.com>
[rjohnston@sgi.com renumbered test to next in group sequence] 
Signed-off-by: Rich Johnston <rjohnston@sgi.com>

tests/generic/308

@@ -0,0 +1,69 @@
+#! /bin/bash
+# FS QA Test No. 308
+#
+# Regression test for commit:
+# f17722f ext4: Fix max file size and logical block counting of extent format file
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2013 Red Hat, Inc.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $testfile
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+testfile=$TEST_DIR/testfile.$seq
+
+# real QA test starts here
+_supported_fs generic
+_supported_os Linux
+
+rm -f $seq.full
+echo "Silence is golden"
+
+block_size=`stat -f -c %s $TEST_DIR`
+
+# On unpatched ext4, if an extent exists which includes the block right
+# before the maximum file offset, and the block for the maximum file offset
+# is written, the kernel panics
+# On patched ext4, the write would get EFBIG since we lower s_maxbytes by
+# one fs block
+
+# Create a sparse file with an extent lays at one block before old s_maxbytes
+offset=$(((2**32 - 2) * $block_size))
+$XFS_IO_PROG -f -c "pwrite $offset $block_size" -c fsync $testfile >$seq.full 2>&1
+
+# Write to the block after the extent just created
+offset=$(((2**32 - 1) * $block_size))
+$XFS_IO_PROG -f -c "pwrite $offset $block_size" -c fsync $testfile >>$seq.full 2>&1
+
+# Got here without hitting BUG_ON(), test passed
+status=0
+exit

tests/generic/308.out

@@ -0,0 +1,2 @@
+QA output created by 308
+Silence is golden

tests/generic/group

@@ -110,3 +110,4 @@
 300 auto aio enospc preallocrw stress
 306 auto quick rw
 307 auto quick
+308 auto quick