1#!/bin/ksh -p
2#
3# CDDL HEADER START
4#
5# The contents of this file are subject to the terms of the
6# Common Development and Distribution License (the "License").
7# You may not use this file except in compliance with the License.
8#
9# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10# or https://opensource.org/licenses/CDDL-1.0.
11# See the License for the specific language governing permissions
12# and limitations under the License.
13#
14# When distributing Covered Code, include this CDDL HEADER in each
15# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16# If applicable, add the following below this CDDL HEADER, with the
17# fields enclosed by brackets "[]" replaced with your own identifying
18# information: Portions Copyright [yyyy] [name of copyright owner]
19#
20# CDDL HEADER END
21#
22
23#
24# Copyright (c) 2018 by Delphix. All rights reserved.
25#
26
27. $STF_SUITE/include/libtest.shlib
28
29#
30# DESCRIPTION:
31# Make sure errors caused by messages being dropped from the list backing the
32# procfs file are handled gracefully.
33#
34# STRATEGY:
35# 1. Make sure a few entries have been logged.
36# 2. Open the procfs file and start reading from it.
37# 3. Write to the file to cause its contents to be dropped.
38# 4. Resume reading from the first instance, and check that the expected
39#    error is received.
40# 5. Repeat steps 1-4, except instead of dropping all the messages by writing
41#    to the file, cause enough new messages to be written that the old messages
42#    are dropped.
43#
44
45function cleanup
46{
47	echo $default_max_entries >$MAX_ENTRIES_PARAM || log_fail
48}
49
50function sync_n
51{
52	for i in {1..$1}; do
53		sync_pool $TESTPOOL
54	done
55	return 0
56}
57
58function do_test
59{
60	typeset cmd=$1
61
62	# Clear out old entries
63	echo 0 >$TXG_HIST || log_fail
64
65	# Add some new entries
66	sync_n 20
67
68	# Confirm that there actually is something in the file.
69	[[ $(wc -l <$TXG_HIST) -ge 20 ]] || log_fail "expected more entries"
70
71	#
72	# Start reading file, pause and run a command that will cause the
73	# current offset into the file to become invalid, and then try to
74	# finish reading.
75	#
76	{
77		log_must eval "dd bs=512 count=4 >/dev/null"
78		log_must eval "$cmd"
79		log_must eval 'cat 2>&1 >/dev/null | grep "Input/output error"'
80	} <$TXG_HIST
81}
82
83typeset -r TXG_HIST=/proc/spl/kstat/zfs/$TESTPOOL/txgs
84typeset MAX_ENTRIES_PARAM=/sys/module/zfs/parameters/zfs_txg_history
85typeset default_max_entries
86
87log_onexit cleanup
88
89default_max_entries=$(<$MAX_ENTRIES_PARAM) || log_fail
90echo 50 >$MAX_ENTRIES_PARAM || log_fail
91
92# Clear all of the existing entries.
93do_test "echo 0 >$TXG_HIST"
94
95# Add enough new entries to the list that all of the old ones are dropped.
96do_test "sync_n 60"
97
98log_pass "Attempting to read dropped message returns expected error"
99