generic: add a test that stresses metadata eviction

The fsverity test generic/579 could be used to reproduce a regression in
the xfs buffer hashing.  Carlos Maiolino figured out that even removing
the fsverity-specific bits would reproduce the issue.  This test is
thus a copy of generic/579 with the fsverity bits striped out, and
run 5 times as that seems to be the threshold at which the issue
reproduces reliably.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zorro Lang <zlang@kernel.org>

diff --git a/tests/generic/795 b/tests/generic/795
new file mode 100755 (executable)
index 0000000..fa5474c
--- /dev/null
+++ b/tests/generic/795
@@ -0,0 +1,108 @@
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2019 Google LLC
+#
+# FS QA Test 795
+#
+# Race dropping file systems caches vs fsstress an repeated reading of files.
+# Based on generic/579 with the fsverity bits stripped out, and an increased
+# number of runs.
+#
+. ./common/preamble
+_begin_fstest auto stress
+
+stop_run()
+{
+       # Stop all subprocesses.
+       _kill_fsstress
+       touch $tmp.done
+       wait
+}
+
+_cleanup()
+{
+       stop_run
+       rm -f $tmp.*
+}
+
+. ./common/filter
+
+fsv_file_size=10000000
+nproc_enabler=$((4 * LOAD_FACTOR))
+nproc_reader=$((6 * LOAD_FACTOR))
+nproc_stress=$((3 * LOAD_FACTOR))
+runtime=$((20 * TIME_FACTOR))
+
+run_test()
+{
+       rm -rf $tmp.done
+
+       # Create the test files and start the fs-verity enabler processes.
+       for ((proc = 0; proc < nproc_enabler; proc++)); do
+               orig_file=$SCRATCH_MNT/orig$proc
+               fsv_file=$SCRATCH_MNT/fsv$proc
+               head -c $fsv_file_size /dev/urandom > $orig_file
+               (
+                       while [ ! -e $tmp.done ]; do
+                               rm -f $fsv_file
+                               cp $orig_file $fsv_file
+                               # Give the readers some time to read from the file.
+                               sleep 0.$((RANDOM % 100))
+                       done
+               ) &
+       done
+
+       # Start the reader processes.
+       for ((proc = 0; proc < nproc_reader; proc++)); do
+               (
+                       while [ ! -e $tmp.done ]; do
+                               # Choose a random file for each iteration, so that
+                               # sometimes multiple processes read from the same file.
+                               i=$((RANDOM % nproc_enabler))
+                               orig_file=$SCRATCH_MNT/orig$i
+                               fsv_file=$SCRATCH_MNT/fsv$i
+
+                               # After the copy from $orig_file to $fsv_file has
+                               # completed, the contents of these two files should
+                               # match, regardless of whether verity has been enabled
+                               # or not yet (or is currently being enabled).
+                               cmp $orig_file $fsv_file |& _filter_scratch | \
+                                       sed -e "s/'//g" | \
+                                       grep -v "SCRATCH_MNT/fsv$i: No such file or directory" | \
+                                       grep -v "EOF on SCRATCH_MNT/fsv$i"
+                               done
+               ) &
+       done
+
+       # Start a process that occasionally runs 'sync && drop_caches'.  This makes more
+       # reads go through fs-verity for real, rather than just returning pagecache.
+       (
+               while [ ! -e $tmp.done ]; do
+                       sleep 2.$((RANDOM % 100))
+                       _scratch_sync && echo 3 > /proc/sys/vm/drop_caches
+               done
+       ) &
+
+       # Start the fsstress processes.
+       _run_fsstress_bg -p $nproc_stress -l 0 -d $SCRATCH_MNT/stressdir
+
+       # Run for a while.
+       sleep $runtime
+
+       stop_run
+}
+
+for i in $(seq 1 5); do
+       echo "Starting run $i" >> $seqres.full
+
+       _scratch_mkfs &>> $seqres.full
+       _scratch_mount
+       run_test
+       _scratch_unmount
+done
+
+echo "Silence is golden"
+
+# success, all done
+status=0
+exit

diff --git a/tests/generic/795.out b/tests/generic/795.out
new file mode 100644 (file)
index 0000000..cb35700
--- /dev/null
+++ b/tests/generic/795.out
@@ -0,0 +1,2 @@
+QA output created by 795
+Silence is golden