btrfs/330: add test to validate ro/rw subvol mounting

Btrfs has had the ability for almost a decade to allow ro and rw
mounting of subvols.  This behavior specifically

mount -o subvol=foo,ro /some/dir
mount -o subvol=bar,rw /some/other/dir

This seems simple, but because of the limitations of how we did mounting
in ye olde days we would mark the super block as RO and the mount if we
mounted RO first.  In the case above /some/dir would instantiate the
super block as read only and the mount point.  So the second mount
command under the covers would convert the super block to RW, and then
allow the mount to continue.

The results were still consistent, /some/dir was still read only because
the mount was marked read only, but /some/other/dir could be written to.

This is a test to make sure we maintain this behavior, as I almost
regressed this behavior while converting us to the new mount API.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ Fixed mkfs.btrfs redirect. Removed common/filter. ]

diff --git a/tests/btrfs/330 b/tests/btrfs/330
new file mode 100755 (executable)
index 0000000..095f6b3
--- /dev/null
+++ b/tests/btrfs/330
@@ -0,0 +1,53 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2023 Meta Platforms, Inc.  All Rights Reserved.
+#
+# FS QA Test No. btrfs/330
+#
+# Test mounting one subvolume as ro and another as rw
+#
+. ./common/preamble
+_begin_fstest auto quick subvol
+
+_cleanup()
+{
+       rm -rf $TEST_DIR/$seq
+}
+
+# Import common functions.
+. ./common/filter.btrfs
+
+# real QA test starts here
+_supported_fs btrfs
+_require_scratch
+
+$MOUNT_PROG -V | grep -q 'fd-based-mount'
+[ "$?" -eq 0 ] && _notrun "mount uses the new mount api"
+
+_scratch_mkfs >> $seqres.full 2>&1 || _fail "mkfs failed"
+_scratch_mount
+
+# Create our subvolumes to mount
+$BTRFS_UTIL_PROG subvolume create $SCRATCH_MNT/foo | _filter_scratch
+$BTRFS_UTIL_PROG subvolume create $SCRATCH_MNT/bar | _filter_scratch
+
+_scratch_unmount
+
+mkdir -p $TEST_DIR/$seq/foo
+mkdir -p $TEST_DIR/$seq/bar
+
+_mount -t btrfs -o subvol=foo,ro $SCRATCH_DEV $TEST_DIR/$seq/foo
+_mount -t btrfs -o subvol=bar,rw $SCRATCH_DEV $TEST_DIR/$seq/bar
+
+echo "making sure foo is read only"
+touch $TEST_DIR/$seq/foo/baz > /dev/null 2&>1
+ls $TEST_DIR/$seq/foo
+
+echo "making sure bar allows writes"
+touch $TEST_DIR/$seq/bar/qux
+ls $TEST_DIR/$seq/bar
+
+$UMOUNT_PROG $TEST_DIR/$seq/foo
+$UMOUNT_PROG $TEST_DIR/$seq/bar
+
+status=0 ; exit

diff --git a/tests/btrfs/330.out b/tests/btrfs/330.out
new file mode 100644 (file)
index 0000000..4795a2c
--- /dev/null
+++ b/tests/btrfs/330.out
@@ -0,0 +1,6 @@
+QA output created by 330
+Create subvolume 'SCRATCH_MNT/foo'
+Create subvolume 'SCRATCH_MNT/bar'
+making sure foo is read only
+making sure bar allows writes
+qux