btrfs: make all btrfs tests that exercise balance use _run_btrfs_balance_start()

In btrfs-progs v4.10 we had a behaviour change where starting a balance
operation without any filters results in a delay of 10 seconds and a
warning is printed to stdout that warns that a full balance is about to
be made and that it can be a slow operation. The new flag '--full-balance'
was added in that release to avoid the 10 seconds delay and the warning
message.

Our existing helper _run_btrfs_balance_start() uses that new balance flag
if we are running a btrfs-progs version that has it, to avoid that 10
seconds wait.

Make all existing btrfs tests that trigger balance operations use the
_run_btrfs_balance_start() helper, so that we avoid wasting time and
speed up some of the tests. In particular test btrfs/014 is now about 10x
faster and tests btrfs/060 to btrfs/064 3 to 5 times faster (depending
on the fsstress random load).

Besides speeding up many tests that do balance operations it also fixes
functional problems:

1) Since btrfs-progs v4.10 the test case btrfs/014 got broken, because
   its purpose is to run balance and snapshot creation in parallel,
   and that wasn't happening anymore because all snapshots were being
   created during the 10 seconds delay of the first balance operation,
   so balance and snapshot creation was being serialized instead of
   running in parallel.

   Fixing this test to avoid the 10 seconds delay immediately
   exposes a regression that went into kernel 5.7-rc1 which is fixed
   by the following commit

   aec7db3b13a0 ("btrfs: fix setting last_trans for reloc roots")

2) Test cases btrfs/060 to btrfs/064 now spend much more time running
   fsstress, balance and other operations in parallel, there's no
   longer intervals of 10 seconds where balance is not running
   concurrently with those other operations, making the tests a lot
   more useful again.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

common/btrfs

@@ -245,7 +245,7 @@ _btrfs_stress_balance()
 {
 	local options=$@
 	while true; do
-		$BTRFS_UTIL_PROG balance start $options
+		_run_btrfs_balance_start $options >> $seqres.full
 	done
 }
 

tests/btrfs/003

@@ -113,7 +113,7 @@ _test_add()
 			_fail "wipefs failed"
 		$BTRFS_UTIL_PROG device add ${devs[$i]} $SCRATCH_MNT >> $seqres.full 2>&1 || _fail "device add failed"
 	done
-	$BTRFS_UTIL_PROG filesystem balance $SCRATCH_MNT >> $seqres.full 2>&1 || _fail "balance failed"
+	_run_btrfs_balance_start $SCRATCH_MNT >> $seqres.full
 	_scratch_unmount
 }
 
@@ -159,7 +159,7 @@ _test_replace()
 	# in some system balance fails if there is no delay (a bug)
 	# putting sleep 10 to work around as of now
 	# sleep 10
-	$BTRFS_UTIL_PROG filesystem balance $SCRATCH_MNT >> $seqres.full 2>&1 || _fail "dev balance failed"
+	_run_btrfs_balance_start $SCRATCH_MNT >> $seqres.full
 
 	# cleaup. add the removed disk
 	_scratch_unmount

tests/btrfs/013

@@ -56,8 +56,7 @@ _check_csum_error()
 }
 $XFS_IO_PROG -f -c "falloc 0 1M" -c "pwrite 16k 8k" -c "fsync" \
 	$SCRATCH_MNT/foo > $seqres.full 2>&1
-$BTRFS_UTIL_PROG filesystem balance $SCRATCH_MNT >> $seqres.full 2>&1 || \
+_run_btrfs_balance_start $SCRATCH_MNT >> $seqres.full
-	_fail "balance failed"
 _scratch_unmount
 _scratch_mount
 $XFS_IO_PROG -c "pread 0 1M" $SCRATCH_MNT/foo >> $seqres.full 2>&1 || \

tests/btrfs/014

@@ -27,7 +27,7 @@ _balance()
 {
 	for i in $(seq 20)
 	do
-		$BTRFS_UTIL_PROG balance start $SCRATCH_MNT >/dev/null
+		_run_btrfs_balance_start $SCRATCH_MNT >> $seqres.full
 	done
 }
 

tests/btrfs/021

@@ -31,7 +31,7 @@ _cleanup()
 # real QA test starts here
 run_test()
 {
-	$BTRFS_UTIL_PROG balance start $SCRATCH_MNT >> $seqres.full &
+	_run_btrfs_balance_start $SCRATCH_MNT >> $seqres.full &
 
 	sleep 0.5
 

tests/btrfs/102

@@ -47,7 +47,7 @@ _require_fs_space $SCRATCH_MNT $((2 * 1024 * 1024))
 # mkfs created. We could also wait for the background kthread to automatically
 # delete the unused block group, but we do not have a way to make it run and
 # wait for it to complete, so just do a balance instead of some unreliable sleep
-_run_btrfs_util_prog balance start -dusage=0 $SCRATCH_MNT
+_run_btrfs_balance_start -dusage=0 $SCRATCH_MNT >> $seqres.full
 
 # Now unmount the filesystem, mount it again (either with or with space caches
 # enabled, it does not matter to trigger the problem) and attempt to create a

tests/btrfs/123

@@ -59,7 +59,7 @@ _run_btrfs_util_prog quota enable $SCRATCH_MNT
 _run_btrfs_util_prog quota rescan -w $SCRATCH_MNT
 
 # now balance data block groups to corrupt qgroup
-_run_btrfs_util_prog balance start -d $SCRATCH_MNT
+_run_btrfs_balance_start -d $SCRATCH_MNT >> $seqres.full
 
 _scratch_unmount
 # qgroup will be check at _check_scratch_fs() by fstest

tests/btrfs/125

@@ -123,7 +123,7 @@ _run_btrfs_util_prog device scan
 _scratch_mount >> $seqres.full 2>&1
 
 echo >> $seqres.full
-_run_btrfs_util_prog balance start ${SCRATCH_MNT}
+_run_btrfs_balance_start $SCRATCH_MNT >> $seqres.full
 
 _run_btrfs_util_prog filesystem show
 _run_btrfs_util_prog filesystem df ${SCRATCH_MNT}

tests/btrfs/154

@@ -129,8 +129,8 @@ balance_convert()
 	echo
 	echo "run balance"
 
-	_run_btrfs_util_prog balance start --full-balance -dconvert=raid1 \
+	_run_btrfs_balance_start -dconvert=raid1 \
-				-mconvert=raid1 ${SCRATCH_MNT}
+				 -mconvert=raid1 $SCRATCH_MNT >> $seqres.full
 }
 
 verify()

tests/btrfs/156

@@ -70,14 +70,14 @@ sync
 # Now we have take at least 50% of the filesystem, relocate all chunks twice
 # so all chunks will start after 1G in logical space.
 # (Btrfs chunk allocation will not rewind to reuse lower space)
-_run_btrfs_util_prog balance start --full-balance "$SCRATCH_MNT"
+_run_btrfs_balance_start $SCRATCH_MNT >> $seqres.full
 
 # To avoid possible false ENOSPC alert on v4.15-rc1, seems to be a
 # reserved space related bug (maybe related to outstanding space rework?),
 # but that's another story.
 sync
 
-_run_btrfs_util_prog balance start --full-balance "$SCRATCH_MNT"
+_run_btrfs_balance_start $SCRATCH_MNT >> $seqres.full
 
 # Now remove half of the files to make some holes for later trim.
 # While still keep the chunk space fragmented, so no chunk will be freed

tests/btrfs/181

@@ -68,7 +68,7 @@ sync
 
 before_gen=$(get_super_gen)
 
-$BTRFS_UTIL_PROG balance start -m "$SCRATCH_MNT" > /dev/null
+_run_btrfs_balance_start -m $SCRATCH_MNT >> $seqres.full
 
 after_gen=$(get_super_gen)
 

tests/btrfs/182

@@ -53,7 +53,7 @@ for ((i = 0; i < $nr_files; i++)) do
 	_pwrite_byte 0xcd 0 1K "$SCRATCH_MNT/subvol/file_$i" > /dev/null
 done
 
-$BTRFS_UTIL_PROG balance start -m "$SCRATCH_MNT" > /dev/null
+_run_btrfs_balance_start -m $SCRATCH_MNT >> $seqres.full
 
 # success, all done
 echo "Silence is golden"

tests/btrfs/187

@@ -84,7 +84,7 @@ balance_loop()
 		# easier to hit problems (crashes and errors) in send.
 		# Ignore errors from balance. We just want to test for crashes
 		# and deadlocks.
-		$BTRFS_UTIL_PROG balance start -f -m $SCRATCH_MNT &> /dev/null
+		_run_btrfs_balance_start -f -m $SCRATCH_MNT &> /dev/null
 		sleep $((RANDOM % 3))
 	done
 }

tests/btrfs/190

@@ -59,7 +59,8 @@ sync
 
 # Balance metadata so we will have at least one transaction committed with
 # valid reloc tree, and hopefully another commit with orphan reloc tree.
-$BTRFS_UTIL_PROG balance start -f -m $SCRATCH_MNT >> $seqres.full
+_run_btrfs_balance_start -f -m $SCRATCH_MNT >> $seqres.full
+
 _log_writes_unmount
 _log_writes_remove
 

tests/btrfs/195

@@ -64,7 +64,7 @@ run_testcase() {
 	# Create random filesystem with 20k write ops
 	$FSSTRESS_PROG -d $SCRATCH_MNT -w -n 10000 $FSSTRESS_AVOID >>$seqres.full 2>&1
 
-	$BTRFS_UTIL_PROG balance start -f -dconvert=$dst_type $SCRATCH_MNT >> $seqres.full 2>&1
+	_run_btrfs_balance_start -f -dconvert=$dst_type $SCRATCH_MNT >> $seqres.full
 	[ $? -eq 0 ] || echo "$1: Failed convert"
 
 	$BTRFS_UTIL_PROG scrub start -B $SCRATCH_MNT >>$seqres.full 2>&1