3246 ZFS I/O deadman thread

Reviewed by: Matt Ahrens <[email protected]>
Reviewed by: Eric Schrock <[email protected]>
Reviewed by: Christopher Siden <[email protected]>
Approved by: Garrett D'Amore <[email protected]>

NOTES: This patch has been reworked from the original in the
following ways to accomidate Linux ZFS implementation

*) Usage of the cyclic interface was replaced by the delayed taskq
   interface.  This avoids the need to implement new compatibility
   code and allows us to rely on the existing taskq implementation.

*) An extern for zfs_txg_synctime_ms was added to sys/dsl_pool.h
   because declaring externs in source files as was done in the
   original patch is just plain wrong.

*) Instead of panicing the system when the deadman triggers a
   zevent describing the blocked vdev and the first pending I/O
   is posted.  If the panic behavior is desired Linux provides
   other generic methods to panic the system when threads are
   observed to hang.

*) For reference, to delay zios by 30 seconds for testing you can
   use zinject as follows: 'zinject -d <vdev> -D30 <pool>'

References:
  illumos/illumos-gate@283b84606b6fc326692c03273de1774e8c122f9a
  https://www.illumos.org/issues/3246

Ported-by: Brian Behlendorf <[email protected]>
Closes #1396

20 files changed, 275 insertions, 50 deletions

diff --git a/cmd/zinject/translate.c b/cmd/zinject/translate.c
index 160786641..fc1612738 100644
--- a/cmd/zinject/translate.c
+++ b/cmd/zinject/translate.c
@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 #include <libzfs.h>
@@ -476,6 +477,20 @@ translate_device(const char *pool, const char *device, err_type_t label_type,
 		    &record->zi_guid) == 0);
 	}
 
+	/*
+	 * Device faults can take on three different forms:
+	 * 1). delayed or hanging I/O
+	 * 2). zfs label faults
+	 * 3). generic disk faults
+	 */
+	if (record->zi_timer != 0) {
+		record->zi_cmd = ZINJECT_DELAY_IO;
+	} else if (label_type != TYPE_INVAL) {
+		record->zi_cmd = ZINJECT_LABEL_FAULT;
+	} else {
+		record->zi_cmd = ZINJECT_DEVICE_FAULT;
+	}
+
 	switch (label_type) {
 	default:
 		break;
diff --git a/cmd/zinject/zinject.c b/cmd/zinject/zinject.c
index d584eadd8..9ae3f9ddc 100644
--- a/cmd/zinject/zinject.c
+++ b/cmd/zinject/zinject.c
@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 /*
@@ -235,8 +236,8 @@ usage(void)
 	    "\t\t'pad1', or 'pad2'.\n"
 	    "\t\t'errno' can be 'nxio' (the default), 'io', or 'dtl'.\n"
 	    "\n"
-	    "\tzinject -d device -A <degrade|fault> pool\n"
-	    "\t\tPerform a specific action on a particular device\n"
+	    "\tzinject -d device -A <degrade|fault> -D <delay secs> pool\n"
+	    "\t\tPerform a specific action on a particular device.\n"
 	    "\n"
 	    "\tzinject -I [-s <seconds> | -g <txgs>] pool\n"
 	    "\t\tCause the pool to stop writing blocks yet not\n"
@@ -589,7 +590,7 @@ main(int argc, char **argv)
 	}
 
 	while ((c = getopt(argc, argv,
-	    ":aA:b:d:f:Fg:qhIc:t:T:l:mr:s:e:uL:p:")) != -1) {
+	    ":aA:b:d:D:f:Fg:qhIc:t:T:l:mr:s:e:uL:p:")) != -1) {
 		switch (c) {
 		case 'a':
 			flags |= ZINJECT_FLUSH_ARC;
@@ -615,6 +616,16 @@ main(int argc, char **argv)
 		case 'd':
 			device = optarg;
 			break;
+		case 'D':
+			errno = 0;
+			record.zi_timer = strtoull(optarg, &end, 10);
+			if (errno != 0 || *end != '\0') {
+				(void) fprintf(stderr, "invalid i/o delay "
+				    "value: '%s'\n", optarg);
+				usage();
+				return (1);
+			}
+			break;
 		case 'e':
 			if (strcasecmp(optarg, "io") == 0) {
 				error = EIO;
@@ -679,6 +690,7 @@ main(int argc, char **argv)
 		case 'p':
 			(void) strlcpy(record.zi_func, optarg,
 			    sizeof (record.zi_func));
+			record.zi_cmd = ZINJECT_PANIC;
 			break;
 		case 'q':
 			quiet = 1;
@@ -762,13 +774,15 @@ main(int argc, char **argv)
 		return (1);
 	}
 
+	if (record.zi_duration != 0)
+		record.zi_cmd = ZINJECT_IGNORED_WRITES;
+
 	if (cancel != NULL) {
 		/*
 		 * '-c' is invalid with any other options.
 		 */
 		if (raw != NULL || range != NULL || type != TYPE_INVAL ||
-		    level != 0 || record.zi_func[0] != '\0' ||
-		    record.zi_duration != 0) {
+		    level != 0 || record.zi_cmd != ZINJECT_UNINITIALIZED) {
 			(void) fprintf(stderr, "cancel (-c) incompatible with "
 			    "any other options\n");
 			usage();
@@ -800,8 +814,7 @@ main(int argc, char **argv)
 		 * for doing injection, so handle it separately here.
 		 */
 		if (raw != NULL || range != NULL || type != TYPE_INVAL ||
-		    level != 0 || record.zi_func[0] != '\0' ||
-		    record.zi_duration != 0) {
+		    level != 0 || record.zi_cmd != ZINJECT_UNINITIALIZED) {
 			(void) fprintf(stderr, "device (-d) incompatible with "
 			    "data error injection\n");
 			usage();
@@ -835,7 +848,7 @@ main(int argc, char **argv)
 
 	} else if (raw != NULL) {
 		if (range != NULL || type != TYPE_INVAL || level != 0 ||
-		    record.zi_func[0] != '\0' || record.zi_duration != 0) {
+		    record.zi_cmd != ZINJECT_UNINITIALIZED) {
 			(void) fprintf(stderr, "raw (-b) format with "
 			    "any other options\n");
 			usage();
@@ -858,13 +871,14 @@ main(int argc, char **argv)
 			return (1);
 		}
 
+		record.zi_cmd = ZINJECT_DATA_FAULT;
 		if (translate_raw(raw, &record) != 0)
 			return (1);
 		if (!error)
 			error = EIO;
-	} else if (record.zi_func[0] != '\0') {
+	} else if (record.zi_cmd == ZINJECT_PANIC) {
 		if (raw != NULL || range != NULL || type != TYPE_INVAL ||
-		    level != 0 || device != NULL || record.zi_duration != 0) {
+		    level != 0 || device != NULL) {
 			(void) fprintf(stderr, "panic (-p) incompatible with "
 			    "other options\n");
 			usage();
@@ -882,7 +896,7 @@ main(int argc, char **argv)
 		if (argv[1] != NULL)
 			record.zi_type = atoi(argv[1]);
 		dataset[0] = '\0';
-	} else if (record.zi_duration != 0) {
+	} else if (record.zi_cmd == ZINJECT_IGNORED_WRITES) {
 		if (nowrites == 0) {
 			(void) fprintf(stderr, "-s or -g meaningless "
 			    "without -I (ignore writes)\n");
@@ -936,6 +950,7 @@ main(int argc, char **argv)
 			return (1);
 		}
 
+		record.zi_cmd = ZINJECT_DATA_FAULT;
 		if (translate_record(type, argv[0], range, level, &record, pool,
 		    dataset) != 0)
 			return (1);
diff --git a/include/sys/dsl_pool.h b/include/sys/dsl_pool.h
index ff5df1414..96a2296bf 100644
--- a/include/sys/dsl_pool.h
+++ b/include/sys/dsl_pool.h
@@ -41,6 +41,8 @@
 extern "C" {
 #endif
 
+extern int zfs_txg_synctime_ms;
+
 struct objset;
 struct dsl_dir;
 struct dsl_dataset;
diff --git a/include/sys/fm/fs/zfs.h b/include/sys/fm/fs/zfs.h
index d5c6004c2..741b99e62 100644
--- a/include/sys/fm/fs/zfs.h
+++ b/include/sys/fm/fs/zfs.h
@@ -73,6 +73,8 @@ extern "C" {
 #define	FM_EREPORT_PAYLOAD_ZFS_VDEV_FRU		"vdev_fru"
 #define	FM_EREPORT_PAYLOAD_ZFS_VDEV_STATE	"vdev_state"
 #define	FM_EREPORT_PAYLOAD_ZFS_VDEV_ASHIFT	"vdev_ashift"
+#define	FM_EREPORT_PAYLOAD_ZFS_VDEV_COMP_TS	"vdev_complete_ts"
+#define	FM_EREPORT_PAYLOAD_ZFS_VDEV_DELTA_TS	"vdev_delta_ts"
 #define	FM_EREPORT_PAYLOAD_ZFS_PARENT_GUID	"parent_guid"
 #define	FM_EREPORT_PAYLOAD_ZFS_PARENT_TYPE	"parent_type"
 #define	FM_EREPORT_PAYLOAD_ZFS_PARENT_PATH	"parent_path"
@@ -88,6 +90,9 @@ extern "C" {
 #define	FM_EREPORT_PAYLOAD_ZFS_ZIO_STAGE	"zio_stage"
 #define	FM_EREPORT_PAYLOAD_ZFS_ZIO_PIPELINE	"zio_pipeline"
 #define	FM_EREPORT_PAYLOAD_ZFS_ZIO_DELAY	"zio_delay"
+#define	FM_EREPORT_PAYLOAD_ZFS_ZIO_TIMESTAMP	"zio_timestamp"
+#define	FM_EREPORT_PAYLOAD_ZFS_ZIO_DEADLINE	"zio_deadline"
+#define	FM_EREPORT_PAYLOAD_ZFS_ZIO_DELTA	"zio_delta"
 #define	FM_EREPORT_PAYLOAD_ZFS_PREV_STATE	"prev_state"
 #define	FM_EREPORT_PAYLOAD_ZFS_CKSUM_EXPECTED	"cksum_expected"
 #define	FM_EREPORT_PAYLOAD_ZFS_CKSUM_ACTUAL	"cksum_actual"
diff --git a/include/sys/spa.h b/include/sys/spa.h
index 821172297..ca9fb2438 100644
--- a/include/sys/spa.h
+++ b/include/sys/spa.h
@@ -570,6 +570,7 @@ extern int spa_offline_log(spa_t *spa);
 
 /* Log claim callback */
 extern void spa_claim_notify(zio_t *zio);
+extern void spa_deadman(void *);
 
 /* Accessor functions */
 extern boolean_t spa_shutting_down(spa_t *spa);
@@ -604,6 +605,7 @@ extern boolean_t spa_suspended(spa_t *spa);
 extern uint64_t spa_bootfs(spa_t *spa);
 extern uint64_t spa_delegation(spa_t *spa);
 extern objset_t *spa_meta_objset(spa_t *spa);
+extern uint64_t spa_deadman_synctime(spa_t *spa);
 
 /* Miscellaneous support routines */
 extern void spa_activate_mos_feature(spa_t *spa, const char *feature);
diff --git a/include/sys/spa_impl.h b/include/sys/spa_impl.h
index 65edc97f5..5bd0e0a9c 100644
--- a/include/sys/spa_impl.h
+++ b/include/sys/spa_impl.h
@@ -227,6 +227,10 @@ struct spa {
 	uint64_t	spa_feat_for_write_obj;	/* required to write to pool */
 	uint64_t	spa_feat_for_read_obj;	/* required to read from pool */
 	uint64_t	spa_feat_desc_obj;	/* Feature descriptions */
+	taskqid_t	spa_deadman_tqid;	/* Task id */
+	uint64_t	spa_deadman_calls;	/* number of deadman calls */
+	uint64_t	spa_sync_starttime;	/* starting time fo spa_sync */
+	uint64_t	spa_deadman_synctime;	/* deadman expiration timer */
 	/*
 	 * spa_refcnt & spa_config_lock must be the last elements
 	 * because refcount_t changes size based on compilation options.
diff --git a/include/sys/vdev.h b/include/sys/vdev.h
index 8f297a917..f49086a47 100644
--- a/include/sys/vdev.h
+++ b/include/sys/vdev.h
@@ -78,6 +78,7 @@ extern void vdev_metaslab_fini(vdev_t *vd);
 extern void vdev_metaslab_set_size(vdev_t *);
 extern void vdev_expand(vdev_t *vd, uint64_t txg);
 extern void vdev_split(vdev_t *vd);
+extern void vdev_deadman(vdev_t *vd);
 
 
 extern void vdev_get_stats(vdev_t *vd, vdev_stat_t *vs);
diff --git a/include/sys/vdev_impl.h b/include/sys/vdev_impl.h
index 964ee2407..711408e6a 100644
--- a/include/sys/vdev_impl.h
+++ b/include/sys/vdev_impl.h
@@ -105,6 +105,8 @@ struct vdev_queue {
 	avl_tree_t	vq_read_tree;
 	avl_tree_t	vq_write_tree;
 	avl_tree_t	vq_pending_tree;
+	uint64_t	vq_io_complete_ts;
+	uint64_t	vq_io_delta_ts;
 	list_t		vq_io_list;
 	kmutex_t	vq_lock;
 };
diff --git a/include/sys/zfs_context.h b/include/sys/zfs_context.h
index 53080f382..a23bfdcf8 100644
--- a/include/sys/zfs_context.h
+++ b/include/sys/zfs_context.h
@@ -25,6 +25,7 @@
 /*
  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 #ifndef _SYS_ZFS_CONTEXT_H
@@ -400,6 +401,8 @@ extern taskq_t	*taskq_create(const char *, int, pri_t, int, int, uint_t);
 #define	taskq_create_sysdc(a, b, d, e, p, dc, f) \
 	    (taskq_create(a, b, maxclsyspri, d, e, f))
 extern taskqid_t taskq_dispatch(taskq_t *, task_func_t, void *, uint_t);
+extern taskqid_t taskq_dispatch_delay(taskq_t *, task_func_t, void *, uint_t,
+    clock_t);
 extern void	taskq_dispatch_ent(taskq_t *, task_func_t, void *, uint_t,
     taskq_ent_t *);
 extern int	taskq_empty_ent(taskq_ent_t *);
@@ -407,6 +410,7 @@ extern void	taskq_init_ent(taskq_ent_t *);
 extern void	taskq_destroy(taskq_t *);
 extern void	taskq_wait(taskq_t *);
 extern int	taskq_member(taskq_t *, kthread_t *);
+extern int	taskq_cancel_id(taskq_t *, taskqid_t);
 extern void	system_taskq_init(void);
 extern void	system_taskq_fini(void);
 
@@ -523,6 +527,11 @@ extern vnode_t *rootdir;
 
 extern void delay(clock_t ticks);
 
+#define	SEC_TO_TICK(sec)	((sec) * hz)
+#define	MSEC_TO_TICK(msec)	((msec) / (MILLISEC / hz))
+#define	USEC_TO_TICK(usec)	((usec) / (MICROSEC / hz))
+#define	NSEC_TO_TICK(usec)	((usec) / (NANOSEC / hz))
+
 #define	gethrestime_sec() time(NULL)
 #define	gethrestime(t) \
 	do {\
diff --git a/include/sys/zfs_ioctl.h b/include/sys/zfs_ioctl.h
index 740d8eda4..c0cb4705d 100644
--- a/include/sys/zfs_ioctl.h
+++ b/include/sys/zfs_ioctl.h
@@ -236,6 +236,8 @@ typedef struct zinject_record {
 	uint32_t	zi_iotype;
 	int32_t		zi_duration;
 	uint64_t	zi_timer;
+	uint32_t	zi_cmd;
+	uint32_t	zi_pad;
 } zinject_record_t;
 
 #define	ZINJECT_NULL		0x1
@@ -245,6 +247,16 @@ typedef struct zinject_record {
 #define	ZEVENT_NONBLOCK		0x1
 #define	ZEVENT_SIZE		1024
 
+typedef enum zinject_type {
+	ZINJECT_UNINITIALIZED,
+	ZINJECT_DATA_FAULT,
+	ZINJECT_DEVICE_FAULT,
+	ZINJECT_LABEL_FAULT,
+	ZINJECT_IGNORED_WRITES,
+	ZINJECT_PANIC,
+	ZINJECT_DELAY_IO,
+} zinject_type_t;
+
 typedef struct zfs_share {
 	uint64_t	z_exportdata;
 	uint64_t	z_sharedata;
diff --git a/include/sys/zio.h b/include/sys/zio.h
index 64efde016..03530330c 100644
--- a/include/sys/zio.h
+++ b/include/sys/zio.h
@@ -21,8 +21,6 @@
 
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- */
-/*
  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
  * Copyright (c) 2012 by Delphix. All rights reserved.
  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
@@ -411,7 +409,10 @@ struct zio {
 	const zio_vsd_ops_t *io_vsd_ops;
 
 	uint64_t	io_offset;
-	uint64_t	io_deadline;
+	uint64_t	io_deadline;	/* expires at timestamp + deadline */
+	uint64_t	io_timestamp;	/* submitted at (ticks) */
+	uint64_t	io_delta;	/* vdev queue service delta (ticks) */
+	uint64_t	io_delay;	/* vdev disk service delta (ticks) */
 	avl_node_t	io_offset_node;
 	avl_node_t	io_deadline_node;
 	avl_tree_t	*io_vdev_tree;
@@ -423,7 +424,6 @@ struct zio {
 	enum zio_flag	io_orig_flags;
 	enum zio_stage	io_orig_stage;
 	enum zio_stage	io_orig_pipeline;
-	uint64_t	io_delay;
 	int		io_error;
 	int		io_child_error[ZIO_CHILD_TYPES];
 	uint64_t	io_children[ZIO_CHILD_TYPES][ZIO_WAIT_TYPES];
@@ -560,6 +560,7 @@ extern int zio_handle_fault_injection(zio_t *zio, int error);
 extern int zio_handle_device_injection(vdev_t *vd, zio_t *zio, int error);
 extern int zio_handle_label_injection(zio_t *zio, int error);
 extern void zio_handle_ignored_writes(zio_t *zio);
+extern uint64_t zio_handle_io_delay(zio_t *zio);
 
 /*
  * Checksum ereport functions
diff --git a/lib/libzpool/taskq.c b/lib/libzpool/taskq.c
index 803f7dc37..64e214205 100644
--- a/lib/libzpool/taskq.c
+++ b/lib/libzpool/taskq.c
@@ -147,6 +147,13 @@ taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
 	return (1);
 }
 
+taskqid_t
+taskq_dispatch_delay(taskq_t *tq,  task_func_t func, void *arg, uint_t tqflags,
+    clock_t expire_time)
+{
+	return (0);
+}
+
 int
 taskq_empty_ent(taskq_ent_t *t)
 {
@@ -339,6 +346,12 @@ taskq_member(taskq_t *tq, kthread_t *t)
 	return (0);
 }
 
+int
+taskq_cancel_id(taskq_t *tq, taskqid_t id)
+{
+	return (ENOENT);
+}
+
 void
 system_taskq_init(void)
 {
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index 0babf4752..0d3537eaa 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -1013,6 +1013,8 @@ spa_deactivate(spa_t *spa)
 	list_destroy(&spa->spa_config_dirty_list);
 	list_destroy(&spa->spa_state_dirty_list);
 
+	taskq_cancel_id(system_taskq, spa->spa_deadman_tqid);
+
 	for (t = 0; t < ZIO_TYPES; t++) {
 		for (q = 0; q < ZIO_TASKQ_TYPES; q++) {
 			if (spa->spa_zio_taskq[t][q] != NULL)
@@ -6017,6 +6019,12 @@ spa_sync(spa_t *spa, uint64_t txg)
 
 	tx = dmu_tx_create_assigned(dp, txg);
 
+	spa->spa_sync_starttime = gethrtime();
+	taskq_cancel_id(system_taskq, spa->spa_deadman_tqid);
+	spa->spa_deadman_tqid = taskq_dispatch_delay(system_taskq,
+	    spa_deadman, spa, TQ_SLEEP, ddi_get_lbolt() +
+	    NSEC_TO_TICK(spa->spa_deadman_synctime));
+
 	/*
 	 * If we are upgrading to SPA_VERSION_RAIDZ_DEFLATE this txg,
 	 * set spa_deflate if we have no raid-z vdevs.
@@ -6145,6 +6153,9 @@ spa_sync(spa_t *spa, uint64_t txg)
 	}
 	dmu_tx_commit(tx);
 
+	taskq_cancel_id(system_taskq, spa->spa_deadman_tqid);
+	spa->spa_deadman_tqid = 0;
+
 	/*
 	 * Clear the dirty config list.
 	 */
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index 5ec8e688e..476f9c02c 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -237,6 +237,24 @@ kmem_cache_t *spa_buffer_pool;
 int spa_mode_global;
 
 /*
+ * Expiration time in units of zfs_txg_synctime_ms. This value has two
+ * meanings. First it is used to determine when the spa_deadman logic
+ * should fire. By default the spa_deadman will fire if spa_sync has
+ * not completed in 1000 * zfs_txg_synctime_ms (i.e. 1000 seconds).
+ * Secondly, the value determines if an I/O is considered "hung".
+ * Any I/O that has not completed in zfs_deadman_synctime is considered
+ * "hung" resulting in a zevent being posted.
+ * 1000 zfs_txg_synctime_ms (i.e. 1000 seconds).
+ */
+unsigned long zfs_deadman_synctime = 1000ULL;
+
+/*
+ * By default the deadman is enabled.
+ */
+int zfs_deadman_enabled = 1;
+
+
+/*
  * ==========================================================================
  * SPA config locking
  * ==========================================================================
@@ -413,6 +431,27 @@ spa_lookup(const char *name)
 }
 
 /*
+ * Fires when spa_sync has not completed within zfs_deadman_synctime_ms.
+ * If the zfs_deadman_enabled flag is set then it inspects all vdev queues
+ * looking for potentially hung I/Os.
+ */
+void
+spa_deadman(void *arg)
+{
+	spa_t *spa = arg;
+
+	zfs_dbgmsg("slow spa_sync: started %llu seconds ago, calls %llu",
+	    (gethrtime() - spa->spa_sync_starttime) / NANOSEC,
+	    ++spa->spa_deadman_calls);
+	if (zfs_deadman_enabled)
+		vdev_deadman(spa->spa_root_vdev);
+
+	spa->spa_deadman_tqid = taskq_dispatch_delay(system_taskq,
+	    spa_deadman, spa, TQ_SLEEP, ddi_get_lbolt() +
+	    NSEC_TO_TICK(spa->spa_deadman_synctime));
+}
+
+/*
  * Create an uninitialized spa_t with the given name.  Requires
  * spa_namespace_lock.  The caller must ensure that the spa_t doesn't already
  * exist by calling spa_lookup() first.
@@ -454,6 +493,9 @@ spa_add(const char *name, nvlist_t *config, const char *altroot)
 	spa->spa_proc = &p0;
 	spa->spa_proc_state = SPA_PROC_NONE;
 
+	spa->spa_deadman_synctime = zfs_deadman_synctime *
+	    zfs_txg_synctime_ms * MICROSEC;
+
 	refcount_create(&spa->spa_refcount);
 	spa_config_lock_init(spa);
 
@@ -1493,6 +1535,12 @@ spa_prev_software_version(spa_t *spa)
 }
 
 uint64_t
+spa_deadman_synctime(spa_t *spa)
+{
+	return (spa->spa_deadman_synctime);
+}
+
+uint64_t
 dva_get_dsize_sync(spa_t *spa, const dva_t *dva)
 {
 	uint64_t asize = DVA_GET_ASIZE(dva);
@@ -1812,4 +1860,10 @@ EXPORT_SYMBOL(spa_writeable);
 EXPORT_SYMBOL(spa_mode);
 
 EXPORT_SYMBOL(spa_namespace_lock);
+
+module_param(zfs_deadman_synctime, ulong, 0644);
+MODULE_PARM_DESC(zfs_deadman_synctime,"Expire in units of zfs_txg_synctime_ms");
+
+module_param(zfs_deadman_enabled, int, 0644);
+MODULE_PARM_DESC(zfs_deadman_enabled, "Enable deadman timer");
 #endif
diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c
index afff4d423..15ff30fb3 100644
--- a/module/zfs/vdev.c
+++ b/module/zfs/vdev.c
@@ -3195,6 +3195,46 @@ vdev_split(vdev_t *vd)
 	vdev_propagate_state(cvd);
 }
 
+void
+vdev_deadman(vdev_t *vd)
+{
+	int c;
+
+	for (c = 0; c < vd->vdev_children; c++) {
+		vdev_t *cvd = vd->vdev_child[c];
+
+		vdev_deadman(cvd);
+	}
+
+	if (vd->vdev_ops->vdev_op_leaf) {
+		vdev_queue_t *vq = &vd->vdev_queue;
+
+		mutex_enter(&vq->vq_lock);
+		if (avl_numnodes(&vq->vq_pending_tree) > 0) {
+			spa_t *spa = vd->vdev_spa;
+			zio_t *fio;
+			uint64_t delta;
+
+			/*
+			 * Look at the head of all the pending queues,
+			 * if any I/O has been outstanding for longer than
+			 * the spa_deadman_synctime we log a zevent.
+			 */
+			fio = avl_first(&vq->vq_pending_tree);
+			delta = ddi_get_lbolt64() - fio->io_timestamp;
+			if (delta > NSEC_TO_TICK(spa_deadman_synctime(spa))) {
+				zfs_dbgmsg("SLOW IO: zio timestamp %llu, "
+				    "delta %llu, last io %llu",
+				    fio->io_timestamp, delta,
+				    vq->vq_io_complete_ts);
+				zfs_ereport_post(FM_EREPORT_ZFS_DELAY,
+				    spa, vd, fio, 0, 0);
+			}
+		}
+		mutex_exit(&vq->vq_lock);
+	}
+}
+
 #if defined(_KERNEL) && defined(HAVE_SPL)
 EXPORT_SYMBOL(vdev_fault);
 EXPORT_SYMBOL(vdev_degrade);
diff --git a/module/zfs/vdev_disk.c b/module/zfs/vdev_disk.c
index 08f64a913..31d1a28bd 100644
--- a/module/zfs/vdev_disk.c
+++ b/module/zfs/vdev_disk.c
@@ -407,8 +407,7 @@ vdev_disk_dio_put(dio_request_t *dr)
 		vdev_disk_dio_free(dr);
 
 		if (zio) {
-			zio->io_delay = jiffies_to_msecs(
-			    jiffies_64 - zio->io_delay);
+			zio->io_delay = jiffies_64 - zio->io_delay;
 			zio->io_error = error;
 			ASSERT3S(zio->io_error, >=, 0);
 			if (zio->io_error)
@@ -609,7 +608,7 @@ BIO_END_IO_PROTO(vdev_disk_io_flush_completion, bio, size, rc)
 {
 	zio_t *zio = bio->bi_private;
 
-	zio->io_delay = jiffies_to_msecs(jiffies_64 - zio->io_delay);
+	zio->io_delay = jiffies_64 - zio->io_delay;
 	zio->io_error = -rc;
 	if (rc && (rc == -EOPNOTSUPP))
 		zio->io_vd->vdev_nowritecache = B_TRUE;
diff --git a/module/zfs/vdev_queue.c b/module/zfs/vdev_queue.c
index e2096fac9..3f2793ba4 100644
--- a/module/zfs/vdev_queue.c
+++ b/module/zfs/vdev_queue.c
@@ -23,6 +23,10 @@
  * Use is subject to license terms.
  */
 
+/*
+ * Copyright (c) 2012 by Delphix. All rights reserved.
+ */
+
 #include <sys/zfs_context.h>
 #include <sys/vdev_impl.h>
 #include <sys/zio.h>
@@ -319,6 +323,7 @@ again:
 		    vi, size, fio->io_type, ZIO_PRIORITY_AGG,
 		    flags | ZIO_FLAG_DONT_CACHE | ZIO_FLAG_DONT_QUEUE,
 		    vdev_queue_agg_io_done, NULL);
+		aio->io_timestamp = fio->io_timestamp;
 
 		nio = fio;
 		do {
@@ -391,7 +396,8 @@ vdev_queue_io(zio_t *zio)
 
 	mutex_enter(&vq->vq_lock);
 
-	zio->io_deadline = (ddi_get_lbolt64() >> zfs_vdev_time_shift) +
+	zio->io_timestamp = ddi_get_lbolt64();
+	zio->io_deadline = (zio->io_timestamp >> zfs_vdev_time_shift) +
 	    zio->io_priority;
 
 	vdev_queue_io_add(vq, zio);
@@ -417,10 +423,17 @@ vdev_queue_io_done(zio_t *zio)
 	vdev_queue_t *vq = &zio->io_vd->vdev_queue;
 	int i;
 
+	if (zio_injection_enabled)
+		delay(SEC_TO_TICK(zio_handle_io_delay(zio)));
+
 	mutex_enter(&vq->vq_lock);
 
 	avl_remove(&vq->vq_pending_tree, zio);
 
+	zio->io_delta = ddi_get_lbolt64() - zio->io_timestamp;
+	vq->vq_io_complete_ts = ddi_get_lbolt64();
+	vq->vq_io_delta_ts = vq->vq_io_complete_ts - zio->io_timestamp;
+
 	for (i = 0; i < zfs_vdev_ramp_rate; i++) {
 		zio_t *nio = vdev_queue_io_to_issue(vq, zfs_vdev_max_pending);
 		if (nio == NULL)
diff --git a/module/zfs/zfs_fm.c b/module/zfs/zfs_fm.c
index 820291bf4..af2030ae7 100644
--- a/module/zfs/zfs_fm.c
+++ b/module/zfs/zfs_fm.c
@@ -250,6 +250,7 @@ zfs_ereport_start(nvlist_t **ereport_out, nvlist_t **detector_out,
 
 	if (vd != NULL) {
 		vdev_t *pvd = vd->vdev_parent;
+		vdev_queue_t *vq = &vd->vdev_queue;
 
 		fm_payload_set(ereport, FM_EREPORT_PAYLOAD_ZFS_VDEV_GUID,
 		    DATA_TYPE_UINT64, vd->vdev_guid,
@@ -272,6 +273,15 @@ zfs_ereport_start(nvlist_t **ereport_out, nvlist_t **detector_out,
 			    FM_EREPORT_PAYLOAD_ZFS_VDEV_ASHIFT,
 			    DATA_TYPE_UINT64, vd->vdev_ashift, NULL);
 
+		if (vq != NULL) {
+			fm_payload_set(ereport,
+			    FM_EREPORT_PAYLOAD_ZFS_VDEV_COMP_TS,
+			    DATA_TYPE_UINT64, vq->vq_io_complete_ts, NULL);
+			fm_payload_set(ereport,
+			    FM_EREPORT_PAYLOAD_ZFS_VDEV_DELTA_TS,
+			    DATA_TYPE_UINT64, vq->vq_io_delta_ts, NULL);
+		}
+
 		if (pvd != NULL) {
 			fm_payload_set(ereport,
 			    FM_EREPORT_PAYLOAD_ZFS_PARENT_GUID,
@@ -304,6 +314,12 @@ zfs_ereport_start(nvlist_t **ereport_out, nvlist_t **detector_out,
 		    DATA_TYPE_UINT32, zio->io_pipeline, NULL);
 		fm_payload_set(ereport, FM_EREPORT_PAYLOAD_ZFS_ZIO_DELAY,
 		    DATA_TYPE_UINT64, zio->io_delay, NULL);
+		fm_payload_set(ereport, FM_EREPORT_PAYLOAD_ZFS_ZIO_TIMESTAMP,
+		    DATA_TYPE_UINT64, zio->io_timestamp, NULL);
+		fm_payload_set(ereport, FM_EREPORT_PAYLOAD_ZFS_ZIO_DEADLINE,
+		    DATA_TYPE_UINT64, zio->io_deadline, NULL);
+		fm_payload_set(ereport, FM_EREPORT_PAYLOAD_ZFS_ZIO_DELTA,
+		    DATA_TYPE_UINT64, zio->io_delta, NULL);
 
 		/*
 		 * If the 'size' parameter is non-zero, it indicates this is a
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index 0622553f5..943f2d677 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -609,6 +609,9 @@ zio_create(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
 	zio->io_vsd_ops = NULL;
 	zio->io_offset = offset;
 	zio->io_deadline = 0;
+	zio->io_timestamp = 0;
+	zio->io_delta = 0;
+	zio->io_delay = 0;
 	zio->io_orig_data = zio->io_data = data;
 	zio->io_orig_size = zio->io_size = size;
 	zio->io_orig_flags = zio->io_flags = flags;
@@ -620,7 +623,6 @@ zio_create(zio_t *pio, spa_t *spa, uint64_t txg, const blkptr_t *bp,
 	zio->io_bp_override = NULL;
 	zio->io_walk_link = NULL;
 	zio->io_transform_stack = NULL;
-	zio->io_delay = 0;
 	zio->io_error = 0;
 	zio->io_child_count = 0;
 	zio->io_parent_count = 0;
@@ -2906,11 +2908,11 @@ zio_done(zio_t *zio)
 	vdev_stat_update(zio, zio->io_size);
 
 	/*
-	 * If this I/O is attached to a particular vdev is slow, exeeding
+	 * If this I/O is attached to a particular vdev is slow, exceeding
 	 * 30 seconds to complete, post an error described the I/O delay.
 	 * We ignore these errors if the device is currently unavailable.
 	 */
-	if (zio->io_delay >= zio_delay_max) {
+	if (zio->io_delay >= MSEC_TO_TICK(zio_delay_max)) {
 		if (zio->io_vd != NULL && !vdev_is_dead(zio->io_vd))
 			zfs_ereport_post(FM_EREPORT_ZFS_DELAY, zio->io_spa,
                                          zio->io_vd, zio, 0, 0);
diff --git a/module/zfs/zio_inject.c b/module/zfs/zio_inject.c
index 293f267fc..eb589c429 100644
--- a/module/zfs/zio_inject.c
+++ b/module/zfs/zio_inject.c
@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 /*
@@ -147,14 +148,8 @@ zio_handle_fault_injection(zio_t *zio, int error)
 	for (handler = list_head(&inject_handlers); handler != NULL;
 	    handler = list_next(&inject_handlers, handler)) {
 
-		/* Ignore errors not destined for this pool */
-		if (zio->io_spa != handler->zi_spa)
-			continue;
-
-		/* Ignore device errors and panic injection */
-		if (handler->zi_record.zi_guid != 0 ||
-		    handler->zi_record.zi_func[0] != '\0' ||
-		    handler->zi_record.zi_duration != 0)
+		if (zio->io_spa != handler->zi_spa ||
+		    handler->zi_record.zi_cmd != ZINJECT_DATA_FAULT)
 			continue;
 
 		/* If this handler matches, return EIO */
@@ -197,10 +192,7 @@ zio_handle_label_injection(zio_t *zio, int error)
 		uint64_t start = handler->zi_record.zi_start;
 		uint64_t end = handler->zi_record.zi_end;
 
-		/* Ignore device only faults or panic injection */
-		if (handler->zi_record.zi_start == 0 ||
-		    handler->zi_record.zi_func[0] != '\0' ||
-		    handler->zi_record.zi_duration != 0)
+		if (handler->zi_record.zi_cmd != ZINJECT_LABEL_FAULT)
 			continue;
 
 		/*
@@ -246,13 +238,7 @@ zio_handle_device_injection(vdev_t *vd, zio_t *zio, int error)
 	for (handler = list_head(&inject_handlers); handler != NULL;
 	    handler = list_next(&inject_handlers, handler)) {
 
-		/*
-		 * Ignore label specific faults, panic injection
-		 * or fake writes
-		 */
-		if (handler->zi_record.zi_start != 0 ||
-		    handler->zi_record.zi_func[0] != '\0' ||
-		    handler->zi_record.zi_duration != 0)
+		if (handler->zi_record.zi_cmd != ZINJECT_DEVICE_FAULT)
 			continue;
 
 		if (vd->vdev_guid == handler->zi_record.zi_guid) {
@@ -316,10 +302,8 @@ zio_handle_ignored_writes(zio_t *zio)
 	    handler = list_next(&inject_handlers, handler)) {
 
 		/* Ignore errors not destined for this pool */
-		if (zio->io_spa != handler->zi_spa)
-			continue;
-
-		if (handler->zi_record.zi_duration == 0)
+		if (zio->io_spa != handler->zi_spa ||
+		    handler->zi_record.zi_cmd != ZINJECT_IGNORED_WRITES)
 			continue;
 
 		/*
@@ -355,11 +339,8 @@ spa_handle_ignored_writes(spa_t *spa)
 	for (handler = list_head(&inject_handlers); handler != NULL;
 	    handler = list_next(&inject_handlers, handler)) {
 
-		/* Ignore errors not destined for this pool */
-		if (spa != handler->zi_spa)
-			continue;
-
-		if (handler->zi_record.zi_duration == 0)
+		if (spa != handler->zi_spa ||
+		    handler->zi_record.zi_cmd != ZINJECT_IGNORED_WRITES)
 			continue;
 
 		if (handler->zi_record.zi_duration > 0) {
@@ -379,6 +360,34 @@ spa_handle_ignored_writes(spa_t *spa)
 	rw_exit(&inject_lock);
 }
 
+uint64_t
+zio_handle_io_delay(zio_t *zio)
+{
+	vdev_t *vd = zio->io_vd;
+	inject_handler_t *handler;
+	uint64_t seconds = 0;
+
+	if (zio_injection_enabled == 0)
+		return (0);
+
+	rw_enter(&inject_lock, RW_READER);
+
+	for (handler = list_head(&inject_handlers); handler != NULL;
+	    handler = list_next(&inject_handlers, handler)) {
+
+		if (handler->zi_record.zi_cmd != ZINJECT_DELAY_IO)
+			continue;
+
+		if (vd->vdev_guid == handler->zi_record.zi_guid) {
+			seconds = handler->zi_record.zi_timer;
+			break;
+		}
+
+	}
+	rw_exit(&inject_lock);
+	return (seconds);
+}
+
 /*
  * Create a new handler for the given record.  We add it to the list, adding
  * a reference to the spa_t in the process.  We increment zio_injection_enabled,