zpool: allow sharing of spare device among pools

ZFS allows, by default, sharing of spare devices among different pools;
this commit simply restores this functionality for disk devices and
adds an additional tests case to the ZFS Test Suite to prevent future
regression.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #7999

cmd/zpool/zpool_vdev.c

@@ -419,11 +419,16 @@ check_disk(const char *path, blkid_cache cache, int force,
 	char slice_path[MAXPATHLEN];
 	int err = 0;
 	int fd, i;
+	int flags = O_RDONLY|O_DIRECT;
 
 	if (!iswholedisk)
 		return (check_slice(path, cache, force, isspare));
 
-	if ((fd = open(path, O_RDONLY|O_DIRECT|O_EXCL)) < 0) {
+	/* only spares can be shared, other devices require exclusive access */
+	if (!isspare)
+		flags |= O_EXCL;
+
+	if ((fd = open(path, flags)) < 0) {
 		char *value = blkid_get_tag_value(cache, "TYPE", path);
 		(void) fprintf(stderr, gettext("%s is in use and contains "
 		    "a %s filesystem.\n"), path, value ? value : "unknown");
@@ -547,7 +552,7 @@ is_spare(nvlist_t *config, const char *path)
 	uint_t i, nspares;
 	boolean_t inuse;
 
-	if ((fd = open(path, O_RDONLY)) < 0)
+	if ((fd = open(path, O_RDONLY|O_DIRECT)) < 0)
 		return (B_FALSE);
 
 	if (zpool_in_use(g_zfs, fd, &state, &name, &inuse) != 0 ||

tests/runfiles/linux.run

@@ -541,7 +541,8 @@ tags = ['functional', 'exec']
 [tests/functional/fault]
 tests = ['auto_online_001_pos', 'auto_replace_001_pos', 'auto_spare_001_pos',
     'auto_spare_002_pos', 'auto_spare_ashift', 'auto_spare_multiple',
-    'scrub_after_resilver', 'decrypt_fault', 'decompress_fault']
+    'auto_spare_shared', 'scrub_after_resilver', 'decrypt_fault',
+    'decompress_fault']
 tags = ['functional', 'fault']
 
 [tests/functional/features/async_destroy]

tests/zfs-tests/include/libtest.shlib

@@ -3190,6 +3190,7 @@ function wait_scrubbed
 {
 	typeset pool=${1:-$TESTPOOL}
 	typeset iter=${2:-10}
+	typeset -i i=0
 	for i in {1..$iter} ; do
 		if is_pool_scrubbed $pool ; then
 			return 0

tests/zfs-tests/tests/functional/fault/Makefile.am

@@ -8,6 +8,7 @@ dist_pkgdata_SCRIPTS = \
 	auto_spare_002_pos.ksh \
 	auto_spare_ashift.ksh \
 	auto_spare_multiple.ksh \
+	auto_spare_shared.ksh \
 	decrypt_fault.ksh \
 	decompress_fault.ksh \
 	scrub_after_resilver.ksh

tests/zfs-tests/tests/functional/fault/auto_spare_shared.ksh

@@ -0,0 +1,119 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# This file and its contents are supplied under the terms of the
+# Common Development and Distribution License ("CDDL"), version 1.0.
+# You may only use this file in accordance with the terms of version
+# 1.0 of the CDDL.
+#
+# A full copy of the text of the CDDL should have accompanied this
+# source.  A copy of the CDDL is also available via the Internet at
+# http://www.illumos.org/license/CDDL.
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright 2018, loli10K <ezomori.nozomu@gmail.com>. All rights reserved.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/include/math.shlib
+. $STF_SUITE/tests/functional/fault/fault.cfg
+
+#
+# DESCRIPTION:
+# Spare devices (both files and disks) can be shared among different ZFS pools.
+#
+# STRATEGY:
+# 1. Create two pools
+# 2. Add the same spare device to different pools
+# 3. Inject IO errors with a zinject error handler
+# 4. Start a scrub
+# 5. Verify the ZED kicks in a hot spare and check pool/device status
+# 6. Clear the fault
+# 7. Verify the hot spare is available and check pool/device status
+#
+
+verify_runnable "both"
+
+if is_linux; then
+	# Add one 512b spare device (4Kn would generate IO errors on replace)
+	# NOTE: must be larger than other "file" vdevs and minimum SPA devsize:
+	# add 32m of fudge
+	load_scsi_debug $(($SPA_MINDEVSIZE/1024/1024+32)) 1 1 1 '512b'
+else
+	log_unsupported "scsi debug module unsupported"
+fi
+
+function cleanup
+{
+	log_must zinject -c all
+	destroy_pool $TESTPOOL
+	destroy_pool $TESTPOOL1
+	unload_scsi_debug
+	rm -f $SAFE_FILEDEVPOOL1 $SAFE_FILEDEVPOOL2 $FAIL_FILEDEVPOOL1 \
+	    $FAIL_FILEDEVPOOL2 $SPARE_FILEDEV
+}
+
+log_assert "Spare devices can be shared among different ZFS pools"
+log_onexit cleanup
+
+# Clear events from previous runs
+zed_events_drain
+
+SAFE_FILEDEVPOOL1="$TEST_BASE_DIR/file-safe-dev1"
+FAIL_FILEDEVPOOL1="$TEST_BASE_DIR/file-fail-dev1"
+SAFE_FILEDEVPOOL2="$TEST_BASE_DIR/file-safe-dev2"
+FAIL_FILEDEVPOOL2="$TEST_BASE_DIR/file-fail-dev2"
+SPARE_FILEDEV="$TEST_BASE_DIR/file-spare-dev"
+SPARE_DISKDEV="$(get_debug_device)"
+
+for vdev in $SAFE_FILEDEVPOOL1 $SAFE_FILEDEVPOOL2 $FAIL_FILEDEVPOOL1 \
+    $FAIL_FILEDEVPOOL2 $SPARE_FILEDEV; do
+	log_must truncate -s $SPA_MINDEVSIZE $vdev
+done
+
+for spare in $SPARE_FILEDEV $SPARE_DISKDEV; do
+	# 1. Create two pools
+	log_must zpool create -f $TESTPOOL mirror $SAFE_FILEDEVPOOL1 $FAIL_FILEDEVPOOL1
+	log_must zpool create -f $TESTPOOL1 mirror $SAFE_FILEDEVPOOL2 $FAIL_FILEDEVPOOL2
+
+	# 2. Add the same spare device to different pools
+	log_must_busy zpool add $TESTPOOL spare $spare
+	log_must_busy zpool add $TESTPOOL1 spare $spare
+	log_must wait_hotspare_state $TESTPOOL $spare "AVAIL"
+	log_must wait_hotspare_state $TESTPOOL1 $spare "AVAIL"
+
+	# 3. Inject IO errors with a zinject error handler
+	log_must zinject -d $FAIL_FILEDEVPOOL1 -e io -T all -f 100 $TESTPOOL
+	log_must zinject -d $FAIL_FILEDEVPOOL2 -e io -T all -f 100 $TESTPOOL1
+
+	# 4. Start a scrub
+	log_must zpool scrub $TESTPOOL
+	log_must zpool scrub $TESTPOOL1
+
+	# 5. Verify the ZED kicks in a hot spare and check pool/device status
+	log_note "Wait for ZED to auto-spare"
+	log_must wait_vdev_state $TESTPOOL $FAIL_FILEDEVPOOL1 "FAULTED" 60
+	log_must wait_vdev_state $TESTPOOL $spare "ONLINE" 60
+	log_must wait_hotspare_state $TESTPOOL $spare "INUSE"
+	log_must check_state $TESTPOOL "" "DEGRADED"
+
+	# 6. Clear the fault
+	log_must zinject -c all
+	log_must zpool clear $TESTPOOL $FAIL_FILEDEVPOOL1
+
+	# 7. Verify the hot spare is available and check pool/device status
+	log_must wait_vdev_state $TESTPOOL $FAIL_FILEDEVPOOL1 "ONLINE" 60
+	log_must wait_hotspare_state $TESTPOOL $spare "AVAIL"
+	log_must is_pool_resilvered $TESTPOOL
+	log_must check_state $TESTPOOL "" "ONLINE"
+
+	# Cleanup
+	destroy_pool $TESTPOOL
+	destroy_pool $TESTPOOL1
+done
+
+log_pass "Spare devices can be shared among different ZFS pools"