spa_misc.c revision 5cabbc6b49070407fb9610cfe73d4c0e0dea3e77
2fa9e406ahrens * CDDL HEADER START
3fa9e406ahrens *
4fa9e406ahrens * The contents of this file are subject to the terms of the
5ea8dc4beschrock * Common Development and Distribution License (the "License").
6ea8dc4beschrock * You may not use this file except in compliance with the License.
7fa9e406ahrens *
8fa9e406ahrens * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9fa9e406ahrens * or
10fa9e406ahrens * See the License for the specific language governing permissions
11fa9e406ahrens * and limitations under the License.
12fa9e406ahrens *
13fa9e406ahrens * When distributing Covered Code, include this CDDL HEADER in each
14fa9e406ahrens * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15fa9e406ahrens * If applicable, add the following below this CDDL HEADER, with the
16fa9e406ahrens * fields enclosed by brackets "[]" replaced with your own identifying
17fa9e406ahrens * information: Portions Copyright [yyyy] [name of copyright owner]
18fa9e406ahrens *
19fa9e406ahrens * CDDL HEADER END
20fa9e406ahrens */
229842588George Wilson * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
2394c2d0eMatthew Ahrens * Copyright (c) 2011, 2017 by Delphix. All rights reserved.
24e495b6eSaso Kiselkov * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
25bc9014eJustin Gibbs * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
2645818eeMatthew Ahrens * Copyright 2013 Saso Kiselkov. All rights reserved.
27c3d26abMatthew Ahrens * Copyright (c) 2014 Integros []
281702cceAlek Pinchuk * Copyright (c) 2017 Datto Inc.
29fa9e406ahrens */
31fa9e406ahrens#include <sys/zfs_context.h>
32fa9e406ahrens#include <sys/spa_impl.h>
33283b846George.Wilson#include <sys/spa_boot.h>
34fa9e406ahrens#include <sys/zio.h>
35fa9e406ahrens#include <sys/zio_checksum.h>
36fa9e406ahrens#include <sys/zio_compress.h>
37fa9e406ahrens#include <sys/dmu.h>
38fa9e406ahrens#include <sys/dmu_tx.h>
39fa9e406ahrens#include <sys/zap.h>
40fa9e406ahrens#include <sys/zil.h>
41fa9e406ahrens#include <sys/vdev_impl.h>
42fa9e406ahrens#include <sys/metaslab.h>
43fa9e406ahrens#include <sys/uberblock_impl.h>
44fa9e406ahrens#include <sys/txg.h>
45fa9e406ahrens#include <sys/avl.h>
46fa9e406ahrens#include <sys/unique.h>
47fa9e406ahrens#include <sys/dsl_pool.h>
48fa9e406ahrens#include <sys/dsl_dir.h>
49fa9e406ahrens#include <sys/dsl_prop.h>
503f9d6adLin Ling#include <sys/dsl_scan.h>
51fa9e406ahrens#include <sys/fs/zfs.h>
526ce0521perrin#include <sys/metaslab_impl.h>
53e14bb32Jeff Bonwick#include <sys/arc.h>
54485bbbfGeorge Wilson#include <sys/ddt.h>
5591ebeefahrens#include "zfs_prop.h"
5645818eeMatthew Ahrens#include <sys/zfeature.h>
59fa9e406ahrens * SPA locking
60fa9e406ahrens *
61fa9e406ahrens * There are four basic locks for managing spa_t structures:
62fa9e406ahrens *
63fa9e406ahrens * spa_namespace_lock (global mutex)
64fa9e406ahrens *
6544cd46cbillm *	This lock must be acquired to do any of the following:
66fa9e406ahrens *
6744cd46cbillm *		- Lookup a spa_t by name
6844cd46cbillm *		- Add or remove a spa_t from the namespace
6944cd46cbillm *		- Increase spa_refcount from non-zero
7044cd46cbillm *		- Check if spa_refcount is zero
7144cd46cbillm *		- Rename a spa_t
72ea8dc4beschrock *		- add/remove/attach/detach devices
7344cd46cbillm *		- Held for the duration of create/destroy/import/export
74fa9e406ahrens *
7544cd46cbillm *	It does not need to handle recursion.  A create or destroy may
7644cd46cbillm *	reference objects (files or zvols) in other pools, but by
7744cd46cbillm *	definition they must have an existing reference, and will never need
7844cd46cbillm *	to lookup a spa_t by name.
79fa9e406ahrens *
80fa9e406ahrens * spa_refcount (per-spa refcount_t protected by mutex)
81fa9e406ahrens *
8244cd46cbillm *	This reference count keep track of any active users of the spa_t.  The
8344cd46cbillm *	spa_t cannot be destroyed or freed while this is non-zero.  Internally,
8444cd46cbillm *	the refcount is never really 'zero' - opening a pool implicitly keeps
85088f389ahrens *	some references in the DMU.  Internally we check against spa_minref, but
8644cd46cbillm *	present the image of a zero/non-zero value to consumers.
87fa9e406ahrens *
88e14bb32Jeff Bonwick * spa_config_lock[] (per-spa array of rwlocks)
89fa9e406ahrens *
9091ebeefahrens *	This protects the spa_t from config changes, and must be held in
9191ebeefahrens *	the following circumstances:
92fa9e406ahrens *
9344cd46cbillm *		- RW_READER to perform I/O to the spa
9444cd46cbillm *		- RW_WRITER to change the vdev config
95fa9e406ahrens *
96fa9e406ahrens * The locking order is fairly straightforward:
97fa9e406ahrens *
9844cd46cbillm *		spa_namespace_lock	->	spa_refcount
99fa9e406ahrens *
10044cd46cbillm *	The namespace lock must be acquired to increase the refcount from 0
10144cd46cbillm *	or to check if it is zero.
102fa9e406ahrens *
103e14bb32Jeff Bonwick *		spa_refcount		->	spa_config_lock[]
104fa9e406ahrens *
10544cd46cbillm *	There must be at least one valid reference on the spa_t to acquire
10644cd46cbillm *	the config lock.
107fa9e406ahrens *
108e14bb32Jeff Bonwick *		spa_namespace_lock	->	spa_config_lock[]
109fa9e406ahrens *
11044cd46cbillm *	The namespace lock must always be taken before the config lock.
111fa9e406ahrens *
112fa9e406ahrens *
113e14bb32Jeff Bonwick * The spa_namespace_lock can be acquired directly and is globally visible.
114fa9e406ahrens *
115e14bb32Jeff Bonwick * The namespace is manipulated using the following functions, all of which
116e14bb32Jeff Bonwick * require the spa_namespace_lock to be held.
117fa9e406ahrens *
11844cd46cbillm *	spa_lookup()		Lookup a spa_t by name.
119fa9e406ahrens *
12044cd46cbillm *	spa_add()		Create a new spa_t in the namespace.
121fa9e406ahrens *
12244cd46cbillm *	spa_remove()		Remove a spa_t from the namespace.  This also
12344cd46cbillm *				frees up any memory associated with the spa_t.
124fa9e406ahrens *
12544cd46cbillm *	spa_next()		Returns the next spa_t in the system, or the
12644cd46cbillm *				first if NULL is passed.
127fa9e406ahrens *
12844cd46cbillm *	spa_evict_all()		Shutdown and remove all spa_t structures in
12944cd46cbillm *				the system.
130fa9e406ahrens *
131ea8dc4beschrock *	spa_guid_exists()	Determine whether a pool/device guid exists.
132fa9e406ahrens *
133fa9e406ahrens * The spa_refcount is manipulated using the following functions:
134fa9e406ahrens *
13544cd46cbillm *	spa_open_ref()		Adds a reference to the given spa_t.  Must be
13644cd46cbillm *				called with spa_namespace_lock held if the
13744cd46cbillm *				refcount is currently zero.
138fa9e406ahrens *
13944cd46cbillm *	spa_close()		Remove a reference from the spa_t.  This will
14044cd46cbillm *				not free the spa_t or remove it from the
14144cd46cbillm *				namespace.  No locking is required.
142fa9e406ahrens *
14344cd46cbillm *	spa_refcount_zero()	Returns true if the refcount is currently
14444cd46cbillm *				zero.  Must be called with spa_namespace_lock
14544cd46cbillm *				held.
146fa9e406ahrens *
147e14bb32Jeff Bonwick * The spa_config_lock[] is an array of rwlocks, ordered as follows:
149e14bb32Jeff Bonwick * spa_config_lock[] is manipulated with spa_config_{enter,exit,held}().
150e14bb32Jeff Bonwick *
151e14bb32Jeff Bonwick * To read the configuration, it suffices to hold one of these locks as reader.
152e14bb32Jeff Bonwick * To modify the configuration, you must hold all locks as writer.  To modify
153e14bb32Jeff Bonwick * vdev state without altering the vdev tree's topology (e.g. online/offline),
154e14bb32Jeff Bonwick * you must hold SCL_STATE and SCL_ZIO as writer.
155e14bb32Jeff Bonwick *
156e14bb32Jeff Bonwick * We use these distinct config locks to avoid recursive lock entry.
157e14bb32Jeff Bonwick * For example, spa_sync() (which holds SCL_CONFIG as reader) induces
158e14bb32Jeff Bonwick * block allocations (SCL_ALLOC), which may require reading space maps
159e14bb32Jeff Bonwick * from disk (dmu_read() -> zio_read() -> SCL_ZIO).
160e14bb32Jeff Bonwick *
161e14bb32Jeff Bonwick * The spa config locks cannot be normal rwlocks because we need the
162e14bb32Jeff Bonwick * ability to hand off ownership.  For example, SCL_ZIO is acquired
163e14bb32Jeff Bonwick * by the issuing thread and later released by an interrupt thread.
164e14bb32Jeff Bonwick * They do, however, obey the usual write-wanted semantics to prevent
165e14bb32Jeff Bonwick * writer (i.e. system administrator) starvation.
166e14bb32Jeff Bonwick *
167e14bb32Jeff Bonwick * The lock acquisition rules are as follows:
168e14bb32Jeff Bonwick *
169e14bb32Jeff Bonwick * SCL_CONFIG
170e14bb32Jeff Bonwick *	Protects changes to the vdev tree topology, such as vdev
171e14bb32Jeff Bonwick *	add/remove/attach/detach.  Protects the dirty config list
172e14bb32Jeff Bonwick *	(spa_config_dirty_list) and the set of spares and l2arc devices.
173e14bb32Jeff Bonwick *
174e14bb32Jeff Bonwick * SCL_STATE
175e14bb32Jeff Bonwick *	Protects changes to pool state and vdev state, such as vdev
176e14bb32Jeff Bonwick *	online/offline/fault/degrade/clear.  Protects the dirty state list
177e14bb32Jeff Bonwick *	(spa_state_dirty_list) and global pool state (spa_state).
178e14bb32Jeff Bonwick *
179e14bb32Jeff Bonwick * SCL_ALLOC
180e14bb32Jeff Bonwick *	Protects changes to metaslab groups and classes.
181e14bb32Jeff Bonwick *	Held as reader by metaslab_alloc() and metaslab_claim().
182e14bb32Jeff Bonwick *
183e14bb32Jeff Bonwick * SCL_ZIO
184e14bb32Jeff Bonwick *	Held by bp-level zios (those which have no io_vd upon entry)
185e14bb32Jeff Bonwick *	to prevent changes to the vdev tree.  The bp-level zio implicitly
186e14bb32Jeff Bonwick *	protects all of its vdev child zios, which do not hold SCL_ZIO.
187e14bb32Jeff Bonwick *
188e14bb32Jeff Bonwick * SCL_FREE
189e14bb32Jeff Bonwick *	Protects changes to metaslab groups and classes.
190e14bb32Jeff Bonwick *	Held as reader by metaslab_free().  SCL_FREE is distinct from
191e14bb32Jeff Bonwick *	SCL_ALLOC, and lower than SCL_ZIO, so that we can safely free
192e14bb32Jeff Bonwick *	blocks in zio_done() while another i/o that holds either
193e14bb32Jeff Bonwick *	SCL_ALLOC or SCL_ZIO is waiting for this i/o to complete.
194e14bb32Jeff Bonwick *
195e14bb32Jeff Bonwick * SCL_VDEV
196e14bb32Jeff Bonwick *	Held as reader to prevent changes to the vdev tree during trivial
197b24ab67Jeff Bonwick *	inquiries such as bp_get_dsize().  SCL_VDEV is distinct from the
198e14bb32Jeff Bonwick *	other locks, and lower than all of them, to ensure that it's safe
199e14bb32Jeff Bonwick *	to acquire regardless of caller context.
200e14bb32Jeff Bonwick *
201e14bb32Jeff Bonwick * In addition, the following rules apply:
202e14bb32Jeff Bonwick *
203e14bb32Jeff Bonwick * (a)	spa_props_lock protects pool properties, spa_config and spa_config_list.
204e14bb32Jeff Bonwick *	The lock ordering is SCL_CONFIG > spa_props_lock.
205e14bb32Jeff Bonwick *
206e14bb32Jeff Bonwick * (b)	I/O operations on leaf vdevs.  For any zio operation that takes
207e14bb32Jeff Bonwick *	an explicit vdev_t argument -- such as zio_ioctl(), zio_read_phys(),
208e14bb32Jeff Bonwick *	or zio_write_phys() -- the caller must ensure that the config cannot
209e14bb32Jeff Bonwick *	cannot change in the interim, and that the vdev cannot be reopened.
210e14bb32Jeff Bonwick *	SCL_STATE as reader suffices for both.
211fa9e406ahrens *
212ea8dc4beschrock * The vdev configuration is protected by spa_vdev_enter() / spa_vdev_exit().
213fa9e406ahrens *
21444cd46cbillm *	spa_vdev_enter()	Acquire the namespace lock and the config lock
215ea8dc4beschrock *				for writing.
216fa9e406ahrens *
21744cd46cbillm *	spa_vdev_exit()		Release the config lock, wait for all I/O
21844cd46cbillm *				to complete, sync the updated configs to the
219ea8dc4beschrock *				cache, and release the namespace lock.
220fa9e406ahrens *
221e14bb32Jeff Bonwick * vdev state is protected by spa_vdev_state_enter() / spa_vdev_state_exit().
222e14bb32Jeff Bonwick * Like spa_vdev_enter/exit, these are convenience wrappers -- the actual
223e14bb32Jeff Bonwick * locking is, always, based on spa_namespace_lock and spa_config_lock[].
224e14bb32Jeff Bonwick *
225ad135b5Christopher Siden * spa_rename() is also implemented within this file since it requires
226e14bb32Jeff Bonwick * manipulation of the namespace.
227fa9e406ahrens */
229fa9e406ahrensstatic avl_tree_t spa_namespace_avl;
230fa9e406ahrenskmutex_t spa_namespace_lock;
231fa9e406ahrensstatic kcondvar_t spa_namespace_cv;
2320373e76bonwickstatic int spa_active_count;
233416e0cdekint spa_max_replication_override = SPA_DVAS_PER_BP;
23599653d4eschrockstatic kmutex_t spa_spare_lock;
23639c2341eschrockstatic avl_tree_t spa_spare_avl;
237fa94a07brendanstatic kmutex_t spa_l2cache_lock;
238fa94a07brendanstatic avl_tree_t spa_l2cache_avl;
240fa9e406ahrenskmem_cache_t *spa_buffer_pool;
2418ad4d6dJeff Bonwickint spa_mode_global;
243fa9e406ahrens#ifdef ZFS_DEBUG
2445cabbc6Prashanth Sreenivasa/*
2455cabbc6Prashanth Sreenivasa * Everything except dprintf, spa, and indirect_remap is on by default
2465cabbc6Prashanth Sreenivasa * in debug builds.
2475cabbc6Prashanth Sreenivasa */
2485cabbc6Prashanth Sreenivasaint zfs_flags = ~(ZFS_DEBUG_DPRINTF | ZFS_DEBUG_SPA | ZFS_DEBUG_INDIRECT_REMAP);
250fa9e406ahrensint zfs_flags = 0;
2540125049ahrens * zfs_recover can be set to nonzero to attempt to recover from
2550125049ahrens * otherwise-fatal errors, typically caused by on-disk corruption.  When
2560125049ahrens * set, calls to zfs_panic_recover() will turn into warning messages.
2578b36997Matthew Ahrens * This should only be used as a last resort, as it typically results
2588b36997Matthew Ahrens * in leaked space, or worse.
2590125049ahrens */
2607fd05acMatthew Ahrensboolean_t zfs_recover = B_FALSE;
2617fd05acMatthew Ahrens
2627fd05acMatthew Ahrens/*
2637fd05acMatthew Ahrens * If destroy encounters an EIO while reading metadata (e.g. indirect
2647fd05acMatthew Ahrens * blocks), space referenced by the missing metadata can not be freed.
2657fd05acMatthew Ahrens * Normally this causes the background destroy to become "stalled", as
2667fd05acMatthew Ahrens * it is unable to make forward progress.  While in this stalled state,
2677fd05acMatthew Ahrens * all remaining space to free from the error-encountering filesystem is
2687fd05acMatthew Ahrens * "temporarily leaked".  Set this flag to cause it to ignore the EIO,
2697fd05acMatthew Ahrens * permanently leak the space from indirect blocks that can not be read,
2707fd05acMatthew Ahrens * and continue to free everything else that it can.
2717fd05acMatthew Ahrens *
2727fd05acMatthew Ahrens * The default, "stalling" behavior is useful if the storage partially
2737fd05acMatthew Ahrens * fails (i.e. some but not all i/os fail), and then later recovers.  In
2747fd05acMatthew Ahrens * this case, we will be able to continue pool operations while it is
2757fd05acMatthew Ahrens * partially failed, and when it recovers, we can continue to free the
2767fd05acMatthew Ahrens * space, with no leaks.  However, note that this case is actually
2777fd05acMatthew Ahrens * fairly rare.
2787fd05acMatthew Ahrens *
2797fd05acMatthew Ahrens * Typically pools either (a) fail completely (but perhaps temporarily,
2807fd05acMatthew Ahrens * e.g. a top-level vdev going offline), or (b) have localized,
2817fd05acMatthew Ahrens * permanent errors (e.g. disk returns the wrong data due to bit flip or
2827fd05acMatthew Ahrens * firmware bug).  In case (a), this setting does not matter because the
2837fd05acMatthew Ahrens * pool will be suspended and the sync thread will not be able to make
2847fd05acMatthew Ahrens * forward progress regardless.  In case (b), because the error is
2857fd05acMatthew Ahrens * permanent, the best we can do is leak the minimum amount of space,
2867fd05acMatthew Ahrens * which is what setting this flag will do.  Therefore, it is reasonable
2877fd05acMatthew Ahrens * for this flag to normally be set, but we chose the more conservative
2887fd05acMatthew Ahrens * approach of not setting it, so that there is no possibility of
2897fd05acMatthew Ahrens * leaking space in the "partial temporary" failure case.
2907fd05acMatthew Ahrens */
2917fd05acMatthew Ahrensboolean_t zfs_free_leak_on_eio = B_FALSE;
29369962b5Matthew Ahrens/*
29469962b5Matthew Ahrens * Expiration time in milliseconds. This value has two meanings. First it is
29569962b5Matthew Ahrens * used to determine when the spa_deadman() logic should fire. By default the
29669962b5Matthew Ahrens * spa_deadman() will fire if spa_sync() has not completed in 1000 seconds.
29769962b5Matthew Ahrens * Secondly, the value determines if an I/O is considered "hung". Any I/O that
29869962b5Matthew Ahrens * has not completed in zfs_deadman_synctime_ms is considered "hung" resulting
29969962b5Matthew Ahrens * in a system panic.
30069962b5Matthew Ahrens */
30169962b5Matthew Ahrensuint64_t zfs_deadman_synctime_ms = 1000000ULL;
30469962b5Matthew Ahrens * Check time in milliseconds. This defines the frequency at which we check
30569962b5Matthew Ahrens * for hung I/O.
306283b846George.Wilson */
30769962b5Matthew Ahrensuint64_t zfs_deadman_checktime_ms = 5000ULL;
310283b846George.Wilson * Override the zfs deadman behavior via /etc/system. By default the
311283b846George.Wilson * deadman is enabled except on VMware and sparc deployments.
312283b846George.Wilson */
313283b846George.Wilsonint zfs_deadman_enabled = -1;
31569962b5Matthew Ahrens/*
31669962b5Matthew Ahrens * The worst case is single-sector max-parity RAID-Z blocks, in which
31769962b5Matthew Ahrens * case the space requirement is exactly (VDEV_RAIDZ_MAXPARITY + 1)
31869962b5Matthew Ahrens * times the size; so just assume that.  Add to this the fact that
31969962b5Matthew Ahrens * we can have up to 3 DVAs per bp, and one more factor of 2 because
32069962b5Matthew Ahrens * the block may be dittoed with up to 3 DVAs by ddt_sync().  All together,
32169962b5Matthew Ahrens * the worst case is:
32269962b5Matthew Ahrens *     (VDEV_RAIDZ_MAXPARITY + 1) * SPA_DVAS_PER_BP * 2 == 24
32369962b5Matthew Ahrens */
32469962b5Matthew Ahrensint spa_asize_inflation = 24;
3277d46dc6Matthew Ahrens * Normally, we don't allow the last 3.2% (1/(2^spa_slop_shift)) of space in
3287d46dc6Matthew Ahrens * the pool to be consumed.  This ensures that we don't run the pool
3297d46dc6Matthew Ahrens * completely out of space, due to unaccounted changes (e.g. to the MOS).
3307d46dc6Matthew Ahrens * It also limits the worst-case time to allocate space.  If we have
3317d46dc6Matthew Ahrens * less than this amount of free space, most ZPL operations (e.g. write,
3327d46dc6Matthew Ahrens * create) will return ENOSPC.
3337d46dc6Matthew Ahrens *
3347d46dc6Matthew Ahrens * Certain operations (e.g. file removal, most administrative actions) can
3357d46dc6Matthew Ahrens * use half the slop space.  They will only return ENOSPC if less than half
3367d46dc6Matthew Ahrens * the slop space is free.  Typically, once the pool has less than the slop
3377d46dc6Matthew Ahrens * space free, the user will use these operations to free up space in the pool.
3387d46dc6Matthew Ahrens * These are the operations that call dsl_pool_adjustedsize() with the netfree
3397d46dc6Matthew Ahrens * argument set to TRUE.
3407d46dc6Matthew Ahrens *
3417d46dc6Matthew Ahrens * A very restricted set of operations are always permitted, regardless of
3427d46dc6Matthew Ahrens * the amount of free space.  These are the operations that call
3437d46dc6Matthew Ahrens * dsl_sync_task(ZFS_SPACE_CHECK_NONE), e.g. "zfs destroy".  If these
3447d46dc6Matthew Ahrens * operations result in a net increase in the amount of space used,
3457d46dc6Matthew Ahrens * it is possible to run the pool completely out of space, causing it to
3467d46dc6Matthew Ahrens * be permanently read-only.
3477d46dc6Matthew Ahrens *
3484b5c8e9Matthew Ahrens * Note that on very small pools, the slop space will be larger than
3494b5c8e9Matthew Ahrens * 3.2%, in an effort to have it be at least spa_min_slop (128MB),
3504b5c8e9Matthew Ahrens * but we never allow it to be more than half the pool size.
3514b5c8e9Matthew Ahrens *
3527d46dc6Matthew Ahrens * See also the comments in zfs_space_check_t.
3537d46dc6Matthew Ahrens */
3547d46dc6Matthew Ahrensint spa_slop_shift = 5;
3554b5c8e9Matthew Ahrensuint64_t spa_min_slop = 128 * 1024 * 1024;
3567d46dc6Matthew Ahrens
3577d46dc6Matthew Ahrens/*
358fa9e406ahrens * ==========================================================================
359e05725bbonwick * SPA config locking
360e05725bbonwick * ==========================================================================
361e05725bbonwick */
362e05725bbonwickstatic void
363e14bb32Jeff Bonwickspa_config_lock_init(spa_t *spa)
364e14bb32Jeff Bonwick{
365e14bb32Jeff Bonwick	for (int i = 0; i < SCL_LOCKS; i++) {
366e14bb32Jeff Bonwick		spa_config_lock_t *scl = &spa->spa_config_lock[i];
367e14bb32Jeff Bonwick		mutex_init(&scl->scl_lock, NULL, MUTEX_DEFAULT, NULL);
368e14bb32Jeff Bonwick		cv_init(&scl->scl_cv, NULL, CV_DEFAULT, NULL);
3693b2aab1Matthew Ahrens		refcount_create_untracked(&scl->scl_count);
370e14bb32Jeff Bonwick		scl->scl_writer = NULL;
371e14bb32Jeff Bonwick		scl->scl_write_wanted = 0;
372e14bb32Jeff Bonwick	}
375e05725bbonwickstatic void
376e14bb32Jeff Bonwickspa_config_lock_destroy(spa_t *spa)
377e14bb32Jeff Bonwick{
378e14bb32Jeff Bonwick	for (int i = 0; i < SCL_LOCKS; i++) {
379e14bb32Jeff Bonwick		spa_config_lock_t *scl = &spa->spa_config_lock[i];
380e14bb32Jeff Bonwick		mutex_destroy(&scl->scl_lock);
381e14bb32Jeff Bonwick		cv_destroy(&scl->scl_cv);
382e14bb32Jeff Bonwick		refcount_destroy(&scl->scl_count);
383e14bb32Jeff Bonwick		ASSERT(scl->scl_writer == NULL);
384e14bb32Jeff Bonwick		ASSERT(scl->scl_write_wanted == 0);
385e14bb32Jeff Bonwick	}
386e14bb32Jeff Bonwick}
387e14bb32Jeff Bonwick
388e14bb32Jeff Bonwickint
389e14bb32Jeff Bonwickspa_config_tryenter(spa_t *spa, int locks, void *tag, krw_t rw)
391e14bb32Jeff Bonwick	for (int i = 0; i < SCL_LOCKS; i++) {
392e14bb32Jeff Bonwick		spa_config_lock_t *scl = &spa->spa_config_lock[i];
393e14bb32Jeff Bonwick		if (!(locks & (1 << i)))
394e14bb32Jeff Bonwick			continue;
395e14bb32Jeff Bonwick		mutex_enter(&scl->scl_lock);
396e14bb32Jeff Bonwick		if (rw == RW_READER) {
397e14bb32Jeff Bonwick			if (scl->scl_writer || scl->scl_write_wanted) {
398e14bb32Jeff Bonwick				mutex_exit(&scl->scl_lock);
399e495b6eSaso Kiselkov				spa_config_exit(spa, locks & ((1 << i) - 1),
400e495b6eSaso Kiselkov				    tag);
401e14bb32Jeff Bonwick				return (0);
402e14bb32Jeff Bonwick			}
403e14bb32Jeff Bonwick		} else {
404e14bb32Jeff Bonwick			ASSERT(scl->scl_writer != curthread);
405e14bb32Jeff Bonwick			if (!refcount_is_zero(&scl->scl_count)) {
406e14bb32Jeff Bonwick				mutex_exit(&scl->scl_lock);
407e495b6eSaso Kiselkov				spa_config_exit(spa, locks & ((1 << i) - 1),
408e495b6eSaso Kiselkov				    tag);
409e14bb32Jeff Bonwick				return (0);
410e14bb32Jeff Bonwick			}
411e14bb32Jeff Bonwick			scl->scl_writer = curthread;
412e14bb32Jeff Bonwick		}
413e14bb32Jeff Bonwick		(void) refcount_add(&scl->scl_count, tag);
414e14bb32Jeff Bonwick		mutex_exit(&scl->scl_lock);
415e14bb32Jeff Bonwick	}
416e14bb32Jeff Bonwick	return (1);
420e14bb32Jeff Bonwickspa_config_enter(spa_t *spa, int locks, void *tag, krw_t rw)
422f64c0e3Eric Taylor	int wlocks_held = 0;
423f64c0e3Eric Taylor
4243b2aab1Matthew Ahrens	ASSERT3U(SCL_LOCKS, <, sizeof (wlocks_held) * NBBY);
4253b2aab1Matthew Ahrens
426e14bb32Jeff Bonwick	for (int i = 0; i < SCL_LOCKS; i++) {
427e14bb32Jeff Bonwick		spa_config_lock_t *scl = &spa->spa_config_lock[i];
428f64c0e3Eric Taylor		if (scl->scl_writer == curthread)
429f64c0e3Eric Taylor			wlocks_held |= (1 << i);
430e14bb32Jeff Bonwick		if (!(locks & (1 << i)))
431e14bb32Jeff Bonwick			continue;
432e14bb32Jeff Bonwick		mutex_enter(&scl->scl_lock);
433e14bb32Jeff Bonwick		if (rw == RW_READER) {
434e14bb32Jeff Bonwick			while (scl->scl_writer || scl->scl_write_wanted) {
435e14bb32Jeff Bonwick				cv_wait(&scl->scl_cv, &scl->scl_lock);
436e14bb32Jeff Bonwick			}
437e14bb32Jeff Bonwick		} else {
438e14bb32Jeff Bonwick			ASSERT(scl->scl_writer != curthread);
439e14bb32Jeff Bonwick			while (!refcount_is_zero(&scl->scl_count)) {
440e14bb32Jeff Bonwick				scl->scl_write_wanted++;
441e14bb32Jeff Bonwick				cv_wait(&scl->scl_cv, &scl->scl_lock);
442e14bb32Jeff Bonwick				scl->scl_write_wanted--;
443e14bb32Jeff Bonwick			}
444e14bb32Jeff Bonwick			scl->scl_writer = curthread;
445e14bb32Jeff Bonwick		}
446e14bb32Jeff Bonwick		(void) refcount_add(&scl->scl_count, tag);
447e14bb32Jeff Bonwick		mutex_exit(&scl->scl_lock);
448e05725bbonwick	}
4495cabbc6Prashanth Sreenivasa	ASSERT3U(wlocks_held, <=, locks);
453e14bb32Jeff Bonwickspa_config_exit(spa_t *spa, int locks, void *tag)
455e14bb32Jeff Bonwick	for (int i = SCL_LOCKS - 1; i >= 0; i--) {
456e14bb32Jeff Bonwick		spa_config_lock_t *scl = &spa->spa_config_lock[i];
457e14bb32Jeff Bonwick		if (!(locks & (1 << i)))
458e14bb32Jeff Bonwick			continue;
459e14bb32Jeff Bonwick		mutex_enter(&scl->scl_lock);
460e14bb32Jeff Bonwick		ASSERT(!refcount_is_zero(&scl->scl_count));
461e14bb32Jeff Bonwick		if (refcount_remove(&scl->scl_count, tag) == 0) {
462e14bb32Jeff Bonwick			ASSERT(scl->scl_writer == NULL ||
463e14bb32Jeff Bonwick			    scl->scl_writer == curthread);
464e14bb32Jeff Bonwick			scl->scl_writer = NULL;	/* OK in either case */
465e14bb32Jeff Bonwick			cv_broadcast(&scl->scl_cv);
466e14bb32Jeff Bonwick		}
467e14bb32Jeff Bonwick		mutex_exit(&scl->scl_lock);
468e05725bbonwick	}
471e14bb32Jeff Bonwickint
472e14bb32Jeff Bonwickspa_config_held(spa_t *spa, int locks, krw_t rw)
474e14bb32Jeff Bonwick	int locks_held = 0;
476e14bb32Jeff Bonwick	for (int i = 0; i < SCL_LOCKS; i++) {
477e14bb32Jeff Bonwick		spa_config_lock_t *scl = &spa->spa_config_lock[i];
478e14bb32Jeff Bonwick		if (!(locks & (1 << i)))
479e14bb32Jeff Bonwick			continue;
480e14bb32Jeff Bonwick		if ((rw == RW_READER && !refcount_is_zero(&scl->scl_count)) ||
481e14bb32Jeff Bonwick		    (rw == RW_WRITER && scl->scl_writer == curthread))
482e14bb32Jeff Bonwick			locks_held |= 1 << i;
483e14bb32Jeff Bonwick	}
484e14bb32Jeff Bonwick
485e14bb32Jeff Bonwick	return (locks_held);
489e05725bbonwick * ==========================================================================
490fa9e406ahrens * SPA namespace functions
491fa9e406ahrens * ==========================================================================
492fa9e406ahrens */
495fa9e406ahrens * Lookup the named spa_t in the AVL tree.  The spa_namespace_lock must be held.
496fa9e406ahrens * Returns NULL if no matching spa_t is found.
497fa9e406ahrens */
498fa9e406ahrensspa_t *
499fa9e406ahrensspa_lookup(const char *name)
501e14bb32Jeff Bonwick	static spa_t search;	/* spa_t is large; don't allocate on stack */
502e14bb32Jeff Bonwick	spa_t *spa;
503fa9e406ahrens	avl_index_t where;
50440feaa9ahrens	char *cp;
506fa9e406ahrens	ASSERT(MUTEX_HELD(&spa_namespace_lock));
5083b2aab1Matthew Ahrens	(void) strlcpy(search.spa_name, name, sizeof (search.spa_name));
5093b2aab1Matthew Ahrens
51040feaa9ahrens	/*
51140feaa9ahrens	 * If it's a full dataset name, figure out the pool name and
51240feaa9ahrens	 * just use that.
51340feaa9ahrens	 */
51478f1710Matthew Ahrens	cp = strpbrk(search.spa_name, "/@#");
5153b2aab1Matthew Ahrens	if (cp != NULL)
51640feaa9ahrens		*cp = '\0';
518fa9e406ahrens	spa = avl_find(&spa_namespace_avl, &search, &where);
520fa9e406ahrens	return (spa);
524283b846George.Wilson * Fires when spa_sync has not completed within zfs_deadman_synctime_ms.
525283b846George.Wilson * If the zfs_deadman_enabled flag is set then it inspects all vdev queues
526283b846George.Wilson * looking for potentially hung I/Os.
527283b846George.Wilson */
529283b846George.Wilsonspa_deadman(void *arg)
531283b846George.Wilson	spa_t *spa = arg;
5330713e23George Wilson	/*
5340713e23George Wilson	 * Disable the deadman timer if the pool is suspended.
5350713e23George Wilson	 */
5360713e23George Wilson	if (spa_suspended(spa)) {
5370713e23George Wilson		VERIFY(cyclic_reprogram(spa->spa_deadman_cycid, CY_INFINITY));
5380713e23George Wilson		return;
5390713e23George Wilson	}
5400713e23George Wilson
541283b846George.Wilson	zfs_dbgmsg("slow spa_sync: started %llu seconds ago, calls %llu",
542283b846George.Wilson	    (gethrtime() - spa->spa_sync_starttime) / NANOSEC,
543283b846George.Wilson	    ++spa->spa_deadman_calls);
544283b846George.Wilson	if (zfs_deadman_enabled)
545283b846George.Wilson		vdev_deadman(spa->spa_root_vdev);
549fa9e406ahrens * Create an uninitialized spa_t with the given name.  Requires
550fa9e406ahrens * spa_namespace_lock.  The caller must ensure that the spa_t doesn't already
551fa9e406ahrens * exist by calling spa_lookup() first.
552fa9e406ahrens */
553fa9e406ahrensspa_t *
554468c413Tim Haleyspa_add(const char *name, nvlist_t *config, const char *altroot)
556fa9e406ahrens	spa_t *spa;
557c5904d1eschrock	spa_config_dirent_t *dp;
558283b846George.Wilson	cyc_handler_t hdlr;
559283b846George.Wilson	cyc_time_t when;
561fa9e406ahrens	ASSERT(MUTEX_HELD(&spa_namespace_lock));
563fa9e406ahrens	spa = kmem_zalloc(sizeof (spa_t), KM_SLEEP);
565c25056dgw	mutex_init(&spa->spa_async_lock, NULL, MUTEX_DEFAULT, NULL);
566c25056dgw	mutex_init(&spa->spa_errlist_lock, NULL, MUTEX_DEFAULT, NULL);
56735a5a35Jonathan Adams	mutex_init(&spa->spa_errlog_lock, NULL, MUTEX_DEFAULT, NULL);
568bc9014eJustin Gibbs	mutex_init(&spa->spa_evicting_os_lock, NULL, MUTEX_DEFAULT, NULL);
569c25056dgw	mutex_init(&spa->spa_history_lock, NULL, MUTEX_DEFAULT, NULL);
57035a5a35Jonathan Adams	mutex_init(&spa->spa_proc_lock, NULL, MUTEX_DEFAULT, NULL);
571c25056dgw	mutex_init(&spa->spa_props_lock, NULL, MUTEX_DEFAULT, NULL);
57245818eeMatthew Ahrens	mutex_init(&spa->spa_cksum_tmpls_lock, NULL, MUTEX_DEFAULT, NULL);
57335a5a35Jonathan Adams	mutex_init(&spa->spa_scrub_lock, NULL, MUTEX_DEFAULT, NULL);
574a152156Jeff Bonwick	mutex_init(&spa->spa_suspend_lock, NULL, MUTEX_DEFAULT, NULL);
575a152156Jeff Bonwick	mutex_init(&spa->spa_vdev_top_lock, NULL, MUTEX_DEFAULT, NULL);
576c3a6601Matthew Ahrens	mutex_init(&spa->spa_iokstat_lock, NULL, MUTEX_DEFAULT, NULL);
5770f7643cGeorge Wilson	mutex_init(&spa->spa_alloc_lock, NULL, MUTEX_DEFAULT, NULL);
579c25056dgw	cv_init(&spa->spa_async_cv, NULL, CV_DEFAULT, NULL);
580bc9014eJustin Gibbs	cv_init(&spa->spa_evicting_os_cv, NULL, CV_DEFAULT, NULL);
58135a5a35Jonathan Adams	cv_init(&spa->spa_proc_cv, NULL, CV_DEFAULT, NULL);
582c25056dgw	cv_init(&spa->spa_scrub_io_cv, NULL, CV_DEFAULT, NULL);
583e14bb32Jeff Bonwick	cv_init(&spa->spa_suspend_cv, NULL, CV_DEFAULT, NULL);
585b24ab67Jeff Bonwick	for (int t = 0; t < TXG_SIZE; t++)
586cde58dbMatthew Ahrens		bplist_create(&spa->spa_free_bplist[t]);
587b24ab67Jeff Bonwick
588e14bb32Jeff Bonwick	(void) strlcpy(spa->spa_name, name, sizeof (spa->spa_name));
589fa9e406ahrens	spa->spa_state = POOL_STATE_UNINITIALIZED;
590fa9e406ahrens	spa->spa_freeze_txg = UINT64_MAX;
5910373e76bonwick	spa->spa_final_txg = UINT64_MAX;
592468c413Tim Haley	spa->spa_load_max_txg = UINT64_MAX;
59335a5a35Jonathan Adams	spa->spa_proc = &p0;
59435a5a35Jonathan Adams	spa->spa_proc_state = SPA_PROC_NONE;
596283b846George.Wilson	hdlr.cyh_func = spa_deadman;
597283b846George.Wilson	hdlr.cyh_arg = spa;
598283b846George.Wilson	hdlr.cyh_level = CY_LOW_LEVEL;
60069962b5Matthew Ahrens	spa->spa_deadman_synctime = MSEC2NSEC(zfs_deadman_synctime_ms);
602283b846George.Wilson	/*
603283b846George.Wilson	 * This determines how often we need to check for hung I/Os after
604283b846George.Wilson	 * the cyclic has already fired. Since checking for hung I/Os is
605283b846George.Wilson	 * an expensive operation we don't want to check too frequently.
60669962b5Matthew Ahrens	 * Instead wait for 5 seconds before checking again.
607283b846George.Wilson	 */
60869962b5Matthew Ahrens	when.cyt_interval = MSEC2NSEC(zfs_deadman_checktime_ms);
609283b846George.Wilson	when.cyt_when = CY_INFINITY;
610283b846George.Wilson	mutex_enter(&cpu_lock);
611283b846George.Wilson	spa->spa_deadman_cycid = cyclic_add(&hdlr, &when);
612283b846George.Wilson	mutex_exit(&cpu_lock);
614fa9e406ahrens	refcount_create(&spa->spa_refcount);
615e14bb32Jeff Bonwick	spa_config_lock_init(spa);
617fa9e406ahrens	avl_add(&spa_namespace_avl, spa);
6190373e76bonwick	/*
6200373e76bonwick	 * Set the alternate root, if there is one.
6210373e76bonwick	 */
6220373e76bonwick	if (altroot) {
6230373e76bonwick		spa->spa_root = spa_strdup(altroot);
6240373e76bonwick		spa_active_count++;
6250373e76bonwick	}
62794c2d0eMatthew Ahrens	avl_create(&spa->spa_alloc_tree, zio_bookmark_compare,
6280f7643cGeorge Wilson	    sizeof (zio_t), offsetof(zio_t, io_alloc_node));
6290f7643cGeorge Wilson
630c5904d1eschrock	/*
631c5904d1eschrock	 * Every pool starts with the default cachefile
632c5904d1eschrock	 */
633c5904d1eschrock	list_create(&spa->spa_config_list, sizeof (spa_config_dirent_t),
634c5904d1eschrock	    offsetof(spa_config_dirent_t, scd_link));
636c5904d1eschrock	dp = kmem_zalloc(sizeof (spa_config_dirent_t), KM_SLEEP);
637ef912c8Tim Haley	dp->scd_path = altroot ? NULL : spa_strdup(spa_config_path);
638c5904d1eschrock	list_insert_head(&spa->spa_config_list, dp);
6404b964adGeorge Wilson	VERIFY(nvlist_alloc(&spa->spa_load_info, NV_UNIQUE_NAME,
6414b964adGeorge Wilson	    KM_SLEEP) == 0);
6424b964adGeorge Wilson
643ad135b5Christopher Siden	if (config != NULL) {
644ad135b5Christopher Siden		nvlist_t *features;
645ad135b5Christopher Siden
646ad135b5Christopher Siden		if (nvlist_lookup_nvlist(config, ZPOOL_CONFIG_FEATURES_FOR_READ,
647ad135b5Christopher Siden		    &features) == 0) {
648ad135b5Christopher Siden			VERIFY(nvlist_dup(features, &spa->spa_label_features,
649ad135b5Christopher Siden			    0) == 0);
650ad135b5Christopher Siden		}
651ad135b5Christopher Siden
652468c413Tim Haley		VERIFY(nvlist_dup(config, &spa->spa_config, 0) == 0);
653ad135b5Christopher Siden	}
654ad135b5Christopher Siden
655ad135b5Christopher Siden	if (spa->spa_label_features == NULL) {
656ad135b5Christopher Siden		VERIFY(nvlist_alloc(&spa->spa_label_features, NV_UNIQUE_NAME,
657ad135b5Christopher Siden		    KM_SLEEP) == 0);
658ad135b5Christopher Siden	}
659468c413Tim Haley
660c3a6601Matthew Ahrens	spa->spa_iokstat = kstat_create("zfs", 0, name,
661c3a6601Matthew Ahrens	    "disk", KSTAT_TYPE_IO, 1, 0);
662c3a6601Matthew Ahrens	if (spa->spa_iokstat) {
663c3a6601Matthew Ahrens		spa->spa_iokstat->ks_lock = &spa->spa_iokstat_lock;
664c3a6601Matthew Ahrens		kstat_install(spa->spa_iokstat);
665c3a6601Matthew Ahrens	}
666c3a6601Matthew Ahrens
6673b2aab1Matthew Ahrens	spa->spa_debug = ((zfs_flags & ZFS_DEBUG_SPA) != 0);
6683b2aab1Matthew Ahrens
66981cd5c5Matthew Ahrens	spa->spa_min_ashift = INT_MAX;
67081cd5c5Matthew Ahrens	spa->spa_max_ashift = 0;
67181cd5c5Matthew Ahrens
67243466aaMax Grossman	/*
67343466aaMax Grossman	 * As a pool is being created, treat all features as disabled by
67443466aaMax Grossman	 * setting SPA_FEATURE_DISABLED for all entries in the feature
67543466aaMax Grossman	 * refcount cache.
67643466aaMax Grossman	 */
67743466aaMax Grossman	for (int i = 0; i < SPA_FEATURES; i++) {
67843466aaMax Grossman		spa->spa_feat_refcount_cache[i] = SPA_FEATURE_DISABLED;
67943466aaMax Grossman	}
68043466aaMax Grossman
681fa9e406ahrens	return (spa);
685fa9e406ahrens * Removes a spa_t from the namespace, freeing up any memory used.  Requires
686fa9e406ahrens * spa_namespace_lock.  This is called only after the spa_t has been closed and
687fa9e406ahrens * deactivated.
688fa9e406ahrens */
690fa9e406ahrensspa_remove(spa_t *spa)
692c5904d1eschrock	spa_config_dirent_t *dp;
694fa9e406ahrens	ASSERT(MUTEX_HELD(&spa_namespace_lock));
695fa9e406ahrens	ASSERT(spa->spa_state == POOL_STATE_UNINITIALIZED);
696bc9014eJustin Gibbs	ASSERT3U(refcount_count(&spa->spa_refcount), ==, 0);
6981195e68Mark J Musante	nvlist_free(spa->spa_config_splitting);
6991195e68Mark J Musante
700fa9e406ahrens	avl_remove(&spa_namespace_avl, spa);
701fa9e406ahrens	cv_broadcast(&spa_namespace_cv);
7030373e76bonwick	if (spa->spa_root) {
704fa9e406ahrens		spa_strfree(spa->spa_root);
7050373e76bonwick		spa_active_count--;
7060373e76bonwick	}
708c5904d1eschrock	while ((dp = list_head(&spa->spa_config_list)) != NULL) {
709c5904d1eschrock		list_remove(&spa->spa_config_list, dp);
710c5904d1eschrock		if (dp->scd_path != NULL)
711c5904d1eschrock			spa_strfree(dp->scd_path);
712c5904d1eschrock		kmem_free(dp, sizeof (spa_config_dirent_t));
713c5904d1eschrock	}
7150f7643cGeorge Wilson	avl_destroy(&spa->spa_alloc_tree);
716c5904d1eschrock	list_destroy(&spa->spa_config_list);
718ad135b5Christopher Siden	nvlist_free(spa->spa_label_features);
7194b964adGeorge Wilson	nvlist_free(spa->spa_load_info);
720fa9e406ahrens	spa_config_set(spa, NULL);
722283b846George.Wilson	mutex_enter(&cpu_lock);
723283b846George.Wilson	if (spa->spa_deadman_cycid != CYCLIC_NONE)
724283b846George.Wilson		cyclic_remove(spa->spa_deadman_cycid);
725283b846George.Wilson	mutex_exit(&cpu_lock);
726283b846George.Wilson	spa->spa_deadman_cycid = CYCLIC_NONE;
728fa9e406ahrens	refcount_destroy(&spa->spa_refcount);
730e14bb32Jeff Bonwick	spa_config_lock_destroy(spa);
732c3a6601Matthew Ahrens	kstat_delete(spa->spa_iokstat);
733c3a6601Matthew Ahrens	spa->spa_iokstat = NULL;
734c3a6601Matthew Ahrens
735b24ab67Jeff Bonwick	for (int t = 0; t < TXG_SIZE; t++)
736cde58dbMatthew Ahrens		bplist_destroy(&spa->spa_free_bplist[t]);
737b24ab67Jeff Bonwick
73845818eeMatthew Ahrens	zio_checksum_templates_free(spa);
73945818eeMatthew Ahrens
740c25056dgw	cv_destroy(&spa->spa_async_cv);
741bc9014eJustin Gibbs	cv_destroy(&spa->spa_evicting_os_cv);
74235a5a35Jonathan Adams	cv_destroy(&spa->spa_proc_cv);
743c25056dgw	cv_destroy(&spa->spa_scrub_io_cv);
744e14bb32Jeff Bonwick	cv_destroy(&spa->spa_suspend_cv);
7460f7643cGeorge Wilson	mutex_destroy(&spa->spa_alloc_lock);
7475ad8204nd	mutex_destroy(&spa->spa_async_lock);
748c25056dgw	mutex_destroy(&spa->spa_errlist_lock);
74935a5a35Jonathan Adams	mutex_destroy(&spa->spa_errlog_lock);
750bc9014eJustin Gibbs	mutex_destroy(&spa->spa_evicting_os_lock);
75106eeb2aek	mutex_destroy(&spa->spa_history_lock);
75235a5a35Jonathan Adams	mutex_destroy(&spa->spa_proc_lock);
753b1b8ab3lling	mutex_destroy(&spa->spa_props_lock);
75445818eeMatthew Ahrens	mutex_destroy(&spa->spa_cksum_tmpls_lock);
75535a5a35Jonathan Adams	mutex_destroy(&spa->spa_scrub_lock);
756e14bb32Jeff Bonwick	mutex_destroy(&spa->spa_suspend_lock);
757a152156Jeff Bonwick	mutex_destroy(&spa->spa_vdev_top_lock);
758c3a6601Matthew Ahrens	mutex_destroy(&spa->spa_iokstat_lock);
760fa9e406ahrens	kmem_free(spa, sizeof (spa_t));
764fa9e406ahrens * Given a pool, return the next pool in the namespace, or NULL if there is
765fa9e406ahrens * none.  If 'prev' is NULL, return the first pool.
766fa9e406ahrens */
767fa9e406ahrensspa_t *
768fa9e406ahrensspa_next(spa_t *prev)
770fa9e406ahrens	ASSERT(MUTEX_HELD(&spa_namespace_lock));
772fa9e406ahrens	if (prev)
773fa9e406ahrens		return (AVL_NEXT(&spa_namespace_avl, prev));
774fa9e406ahrens	else
775fa9e406ahrens		return (avl_first(&spa_namespace_avl));
779fa9e406ahrens * ==========================================================================
780fa9e406ahrens * SPA refcount functions
781fa9e406ahrens * ==========================================================================
782fa9e406ahrens */
785fa9e406ahrens * Add a reference to the given spa_t.  Must have at least one reference, or
786fa9e406ahrens * have the namespace lock held.
787fa9e406ahrens */
789fa9e406ahrensspa_open_ref(spa_t *spa, void *tag)
791088f389ahrens	ASSERT(refcount_count(&spa->spa_refcount) >= spa->spa_minref ||
792fa9e406ahrens	    MUTEX_HELD(&spa_namespace_lock));
793fa9e406ahrens	(void) refcount_add(&spa->spa_refcount, tag);
797fa9e406ahrens * Remove a reference to the given spa_t.  Must have at least one reference, or
798fa9e406ahrens * have the namespace lock held.
799fa9e406ahrens */
801fa9e406ahrensspa_close(spa_t *spa, void *tag)
803088f389ahrens	ASSERT(refcount_count(&spa->spa_refcount) > spa->spa_minref ||
804fa9e406ahrens	    MUTEX_HELD(&spa_namespace_lock));
805fa9e406ahrens	(void) refcount_remove(&spa->spa_refcount, tag);
809bc9014eJustin Gibbs * Remove a reference to the given spa_t held by a dsl dir that is
810bc9014eJustin Gibbs * being asynchronously released.  Async releases occur from a taskq
811bc9014eJustin Gibbs * performing eviction of dsl datasets and dirs.  The namespace lock
812bc9014eJustin Gibbs * isn't held and the hold by the object being evicted may contribute to
813bc9014eJustin Gibbs * spa_minref (e.g. dataset or directory released during pool export),
814bc9014eJustin Gibbs * so the asserts in spa_close() do not apply.
815bc9014eJustin Gibbs */
816bc9014eJustin Gibbsvoid
817bc9014eJustin Gibbsspa_async_close(spa_t *spa, void *tag)
818bc9014eJustin Gibbs{
819bc9014eJustin Gibbs	(void) refcount_remove(&spa->spa_refcount, tag);
820bc9014eJustin Gibbs}
821bc9014eJustin Gibbs
822bc9014eJustin Gibbs/*
823fa9e406ahrens * Check to see if the spa refcount is zero.  Must be called with
824088f389ahrens * spa_namespace_lock held.  We really compare against spa_minref, which is the
825fa9e406ahrens * number of references acquired when opening a pool
826fa9e406ahrens */
828fa9e406ahrensspa_refcount_zero(spa_t *spa)
830fa9e406ahrens	ASSERT(MUTEX_HELD(&spa_namespace_lock));
832088f389ahrens	return (refcount_count(&spa->spa_refcount) == spa->spa_minref);
836fa9e406ahrens * ==========================================================================
837fa94a07brendan * SPA spare and l2cache tracking
83899653d4eschrock * ==========================================================================
83999653d4eschrock */
842fa94a07brendan * Hot spares and cache devices are tracked using the same code below,
843fa94a07brendan * for 'auxiliary' devices.
844fa94a07brendan */
846fa94a07brendantypedef struct spa_aux {
847fa94a07brendan	uint64_t	aux_guid;
848fa94a07brendan	uint64_t	aux_pool;
849fa94a07brendan	avl_node_t	aux_avl;
850fa94a07brendan	int		aux_count;
851fa94a07brendan} spa_aux_t;
853fa94a07brendanstatic int
854fa94a07brendanspa_aux_compare(const void *a, const void *b)
856fa94a07brendan	const spa_aux_t *sa = a;
857fa94a07brendan	const spa_aux_t *sb = b;
859fa94a07brendan	if (sa->aux_guid < sb->aux_guid)
860fa94a07brendan		return (-1);
861fa94a07brendan	else if (sa->aux_guid > sb->aux_guid)
862fa94a07brendan		return (1);
863fa94a07brendan	else
864fa94a07brendan		return (0);
868fa94a07brendanspa_aux_add(vdev_t *vd, avl_tree_t *avl)
870fa94a07brendan	avl_index_t where;
871fa94a07brendan	spa_aux_t search;
872fa94a07brendan	spa_aux_t *aux;
874fa94a07brendan	search.aux_guid = vd->vdev_guid;
875fa94a07brendan	if ((aux = avl_find(avl, &search, &where)) != NULL) {
876fa94a07brendan		aux->aux_count++;
877fa94a07brendan	} else {
878fa94a07brendan		aux = kmem_zalloc(sizeof (spa_aux_t), KM_SLEEP);
879fa94a07brendan		aux->aux_guid = vd->vdev_guid;
880fa94a07brendan		aux->aux_count = 1;
881fa94a07brendan		avl_insert(avl, aux, where);
882fa94a07brendan	}
886fa94a07brendanspa_aux_remove(vdev_t *vd, avl_tree_t *avl)
888fa94a07brendan	spa_aux_t search;
889fa94a07brendan	spa_aux_t *aux;
890fa94a07brendan	avl_index_t where;
892fa94a07brendan	search.aux_guid = vd->vdev_guid;
893fa94a07brendan	aux = avl_find(avl, &search, &where);
895fa94a07brendan	ASSERT(aux != NULL);
897fa94a07brendan	if (--aux->aux_count == 0) {
898fa94a07brendan		avl_remove(avl, aux);