[PATCH] common/rc: fix _try_scratch_mount() and _test_mount() when mount fails

[fdmanana@xxxxxxxxxx]

From: Filipe Manana <fdmanana@xxxxxxxx>

After the recent commit 4a7b35d7a76cd9 ("common: allow to run all tests
on idmapped mounts"), some test that use _try_scratch_mount started to
fail. For example:

$ ./check btrfs/131 btrfs/220
FSTYP         -- btrfs
PLATFORM      -- Linux/x86_64 debian9 5.17.0-rc8-btrfs-next-114 (...)
MKFS_OPTIONS  -- /dev/sdc
MOUNT_OPTIONS -- /dev/sdc /home/fdmanana/btrfs-tests/scratch_1

btrfs/131 2s ... - output mismatch (see .../results//btrfs/131.out.bad)
    --- tests/btrfs/131.out	2020-06-10 19:29:03.818519162 +0100
    +++ /home/fdmanana/git/hub/xfstests/results//btrfs/131.out.bad (...)
    @@ -6,8 +6,6 @@
     Disabling free space cache and enabling free space tree
     free space tree is enabled
     Trying to mount without free space tree
    -mount failed
    -mount failed
     Mounting existing free space tree
     free space tree is enabled
    ...
    (Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/btrfs/131.out ...
btrfs/220 7s ... - output mismatch (see .../results//btrfs/220.out.bad)
    --- tests/btrfs/220.out	2020-10-16 23:13:46.802162554 +0100
    +++ /home/fdmanana/git/hub/xfstests/results//btrfs/220.out.bad (...)
    @@ -1,2 +1,32 @@
     QA output created by 220
    +Option fragment=invalid should fail to mount
    +umount: /home/fdmanana/btrfs-tests/scratch_1: not mounted.
    +Option nologreplay should fail to mount
    +umount: /home/fdmanana/btrfs-tests/scratch_1: not mounted.
    +Option norecovery should fail to mount
    +umount: /home/fdmanana/btrfs-tests/scratch_1: not mounted.
    ...
    (Run 'diff -u /home/fdmanana/git/hub/xfstests/tests/btrfs/220.out ...
Ran: btrfs/131 btrfs/220
Failures: btrfs/131 btrfs/220
Failed 2 of 2 tests

The reason is that if _try_scratch_mount() fails to mount the filesystem,
we don't return the failure, instead we call _idmapped_mount(), which
can succeed and make _try_scratch_mount() return 0 (success). The same
happens for _test_mount(), however a quick search revealed no tests
currently relying on the return value of _test_mount().

So fix that by making _try_scratch_mount() return immediately if it gets
a mount failure. Also do the same for _test_mount().

Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
---
 common/rc | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/common/rc b/common/rc
index 17629801..37d18599 100644
--- a/common/rc
+++ b/common/rc
@@ -329,11 +329,15 @@ _supports_filetype()
 # mount scratch device with given options but don't check mount status
 _try_scratch_mount()
 {
+	local mount_ret
+
 	if [ "$FSTYP" == "overlay" ]; then
 		_overlay_scratch_mount $*
 		return $?
 	fi
 	_mount -t $FSTYP `_scratch_mount_options $*`
+	mount_ret=$?
+	[ $mount_ret -ne 0 ] && return $mount_ret
 	_idmapped_mount $SCRATCH_DEV $SCRATCH_MNT
 }
 
@@ -494,12 +498,16 @@ _idmapped_mount()
 
 _test_mount()
 {
+    local mount_ret
+
     if [ "$FSTYP" == "overlay" ]; then
         _overlay_test_mount $*
         return $?
     fi
     _test_options mount
     _mount -t $FSTYP $TEST_OPTIONS $TEST_FS_MOUNT_OPTS $SELINUX_MOUNT_OPTIONS $* $TEST_DEV $TEST_DIR
+    mount_ret=$?
+    [ $mount_ret -ne 0 ] && return $mount_ret
     _idmapped_mount $TEST_DEV $TEST_DIR
 }
 
-- 
2.35.1