xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/vdev_impl.h (revision 7931524763ef94dc16989451dddd206563d03bb4)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23  * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
24  */
25 
26 #ifndef _SYS_VDEV_IMPL_H
27 #define	_SYS_VDEV_IMPL_H
28 
29 #include <sys/avl.h>
30 #include <sys/bpobj.h>
31 #include <sys/dmu.h>
32 #include <sys/metaslab.h>
33 #include <sys/nvpair.h>
34 #include <sys/space_map.h>
35 #include <sys/vdev.h>
36 #include <sys/dkio.h>
37 #include <sys/uberblock_impl.h>
38 #include <sys/vdev_indirect_mapping.h>
39 #include <sys/vdev_indirect_births.h>
40 #include <sys/vdev_removal.h>
41 
42 #ifdef	__cplusplus
43 extern "C" {
44 #endif
45 
46 /*
47  * Virtual device descriptors.
48  *
49  * All storage pool operations go through the virtual device framework,
50  * which provides data replication and I/O scheduling.
51  */
52 
53 /*
54  * Forward declarations that lots of things need.
55  */
56 typedef struct vdev_queue vdev_queue_t;
57 typedef struct vdev_cache vdev_cache_t;
58 typedef struct vdev_cache_entry vdev_cache_entry_t;
59 struct abd;
60 
61 extern int zfs_vdev_queue_depth_pct;
62 extern int zfs_vdev_def_queue_depth;
63 extern uint32_t zfs_vdev_async_write_max_active;
64 
65 /*
66  * Virtual device operations
67  */
68 typedef int	vdev_open_func_t(vdev_t *vd, uint64_t *size, uint64_t *max_size,
69     uint64_t *ashift);
70 typedef void	vdev_close_func_t(vdev_t *vd);
71 typedef uint64_t vdev_asize_func_t(vdev_t *vd, uint64_t psize);
72 typedef void	vdev_io_start_func_t(zio_t *zio);
73 typedef void	vdev_io_done_func_t(zio_t *zio);
74 typedef void	vdev_state_change_func_t(vdev_t *vd, int, int);
75 typedef void	vdev_hold_func_t(vdev_t *vd);
76 typedef void	vdev_rele_func_t(vdev_t *vd);
77 
78 typedef void	vdev_remap_cb_t(uint64_t inner_offset, vdev_t *vd,
79     uint64_t offset, uint64_t size, void *arg);
80 typedef void	vdev_remap_func_t(vdev_t *vd, uint64_t offset, uint64_t size,
81     vdev_remap_cb_t callback, void *arg);
82 /*
83  * Given a target vdev, translates the logical range "in" to the physical
84  * range "res"
85  */
86 typedef void vdev_xlation_func_t(vdev_t *cvd, const range_seg_t *in,
87     range_seg_t *res);
88 
89 typedef struct vdev_ops {
90 	vdev_open_func_t		*vdev_op_open;
91 	vdev_close_func_t		*vdev_op_close;
92 	vdev_asize_func_t		*vdev_op_asize;
93 	vdev_io_start_func_t		*vdev_op_io_start;
94 	vdev_io_done_func_t		*vdev_op_io_done;
95 	vdev_state_change_func_t	*vdev_op_state_change;
96 	vdev_hold_func_t		*vdev_op_hold;
97 	vdev_rele_func_t		*vdev_op_rele;
98 	vdev_remap_func_t		*vdev_op_remap;
99 	/*
100 	 * For translating ranges from non-leaf vdevs (e.g. raidz) to leaves.
101 	 * Used when initializing vdevs. Isn't used by leaf ops.
102 	 */
103 	vdev_xlation_func_t		*vdev_op_xlate;
104 	char				vdev_op_type[16];
105 	boolean_t			vdev_op_leaf;
106 } vdev_ops_t;
107 
108 /*
109  * Virtual device properties
110  */
111 struct vdev_cache_entry {
112 	struct abd	*ve_abd;
113 	uint64_t	ve_offset;
114 	uint64_t	ve_lastused;
115 	avl_node_t	ve_offset_node;
116 	avl_node_t	ve_lastused_node;
117 	uint32_t	ve_hits;
118 	uint16_t	ve_missed_update;
119 	zio_t		*ve_fill_io;
120 };
121 
122 struct vdev_cache {
123 	avl_tree_t	vc_offset_tree;
124 	avl_tree_t	vc_lastused_tree;
125 	kmutex_t	vc_lock;
126 };
127 
128 typedef struct vdev_queue_class {
129 	uint32_t	vqc_active;
130 
131 	/*
132 	 * Sorted by offset or timestamp, depending on if the queue is
133 	 * LBA-ordered vs FIFO.
134 	 */
135 	avl_tree_t	vqc_queued_tree;
136 } vdev_queue_class_t;
137 
138 struct vdev_queue {
139 	vdev_t		*vq_vdev;
140 	vdev_queue_class_t vq_class[ZIO_PRIORITY_NUM_QUEUEABLE];
141 	avl_tree_t	vq_active_tree;
142 	avl_tree_t	vq_read_offset_tree;
143 	avl_tree_t	vq_write_offset_tree;
144 	uint64_t	vq_last_offset;
145 	hrtime_t	vq_io_complete_ts; /* time last i/o completed */
146 	kmutex_t	vq_lock;
147 };
148 
149 /*
150  * On-disk indirect vdev state.
151  *
152  * An indirect vdev is described exclusively in the MOS config of a pool.
153  * The config for an indirect vdev includes several fields, which are
154  * accessed in memory by a vdev_indirect_config_t.
155  */
156 typedef struct vdev_indirect_config {
157 	/*
158 	 * Object (in MOS) which contains the indirect mapping. This object
159 	 * contains an array of vdev_indirect_mapping_entry_phys_t ordered by
160 	 * vimep_src. The bonus buffer for this object is a
161 	 * vdev_indirect_mapping_phys_t. This object is allocated when a vdev
162 	 * removal is initiated.
163 	 *
164 	 * Note that this object can be empty if none of the data on the vdev
165 	 * has been copied yet.
166 	 */
167 	uint64_t	vic_mapping_object;
168 
169 	/*
170 	 * Object (in MOS) which contains the birth times for the mapping
171 	 * entries. This object contains an array of
172 	 * vdev_indirect_birth_entry_phys_t sorted by vibe_offset. The bonus
173 	 * buffer for this object is a vdev_indirect_birth_phys_t. This object
174 	 * is allocated when a vdev removal is initiated.
175 	 *
176 	 * Note that this object can be empty if none of the vdev has yet been
177 	 * copied.
178 	 */
179 	uint64_t	vic_births_object;
180 
181 	/*
182 	 * This is the vdev ID which was removed previous to this vdev, or
183 	 * UINT64_MAX if there are no previously removed vdevs.
184 	 */
185 	uint64_t	vic_prev_indirect_vdev;
186 } vdev_indirect_config_t;
187 
188 /*
189  * Virtual device descriptor
190  */
191 struct vdev {
192 	/*
193 	 * Common to all vdev types.
194 	 */
195 	uint64_t	vdev_id;	/* child number in vdev parent	*/
196 	uint64_t	vdev_guid;	/* unique ID for this vdev	*/
197 	uint64_t	vdev_guid_sum;	/* self guid + all child guids	*/
198 	uint64_t	vdev_orig_guid;	/* orig. guid prior to remove	*/
199 	uint64_t	vdev_asize;	/* allocatable device capacity	*/
200 	uint64_t	vdev_min_asize;	/* min acceptable asize		*/
201 	uint64_t	vdev_max_asize;	/* max acceptable asize		*/
202 	uint64_t	vdev_ashift;	/* block alignment shift	*/
203 	uint64_t	vdev_state;	/* see VDEV_STATE_* #defines	*/
204 	uint64_t	vdev_prevstate;	/* used when reopening a vdev	*/
205 	vdev_ops_t	*vdev_ops;	/* vdev operations		*/
206 	spa_t		*vdev_spa;	/* spa for this vdev		*/
207 	void		*vdev_tsd;	/* type-specific data		*/
208 	vnode_t		*vdev_name_vp;	/* vnode for pathname		*/
209 	vnode_t		*vdev_devid_vp;	/* vnode for devid		*/
210 	vdev_t		*vdev_top;	/* top-level vdev		*/
211 	vdev_t		*vdev_parent;	/* parent vdev			*/
212 	vdev_t		**vdev_child;	/* array of children		*/
213 	uint64_t	vdev_children;	/* number of children		*/
214 	vdev_stat_t	vdev_stat;	/* virtual device statistics	*/
215 	boolean_t	vdev_expanding;	/* expand the vdev?		*/
216 	boolean_t	vdev_reopening;	/* reopen in progress?		*/
217 	int		vdev_open_error; /* error on last open		*/
218 	kthread_t	*vdev_open_thread; /* thread opening children	*/
219 	uint64_t	vdev_crtxg;	/* txg when top-level was added */
220 
221 	/*
222 	 * Top-level vdev state.
223 	 */
224 	uint64_t	vdev_ms_array;	/* metaslab array object	*/
225 	uint64_t	vdev_ms_shift;	/* metaslab size shift		*/
226 	uint64_t	vdev_ms_count;	/* number of metaslabs		*/
227 	metaslab_group_t *vdev_mg;	/* metaslab group		*/
228 	metaslab_t	**vdev_ms;	/* metaslab array		*/
229 	txg_list_t	vdev_ms_list;	/* per-txg dirty metaslab lists	*/
230 	txg_list_t	vdev_dtl_list;	/* per-txg dirty DTL lists	*/
231 	txg_node_t	vdev_txg_node;	/* per-txg dirty vdev linkage	*/
232 	boolean_t	vdev_remove_wanted; /* async remove wanted?	*/
233 	boolean_t	vdev_probe_wanted; /* async probe wanted?	*/
234 	list_node_t	vdev_config_dirty_node; /* config dirty list	*/
235 	list_node_t	vdev_state_dirty_node; /* state dirty list	*/
236 	uint64_t	vdev_deflate_ratio; /* deflation ratio (x512)	*/
237 	uint64_t	vdev_islog;	/* is an intent log device	*/
238 	uint64_t	vdev_removing;	/* device is being removed?	*/
239 	boolean_t	vdev_ishole;	/* is a hole in the namespace	*/
240 	kmutex_t	vdev_queue_lock; /* protects vdev_queue_depth	*/
241 	uint64_t	vdev_top_zap;
242 
243 	/* pool checkpoint related */
244 	space_map_t	*vdev_checkpoint_sm;	/* contains reserved blocks */
245 
246 	boolean_t	vdev_initialize_exit_wanted;
247 	vdev_initializing_state_t	vdev_initialize_state;
248 	kthread_t	*vdev_initialize_thread;
249 	/* Protects vdev_initialize_thread and vdev_initialize_state. */
250 	kmutex_t	vdev_initialize_lock;
251 	kcondvar_t	vdev_initialize_cv;
252 	uint64_t	vdev_initialize_offset[TXG_SIZE];
253 	uint64_t	vdev_initialize_last_offset;
254 	range_tree_t	*vdev_initialize_tree;	/* valid while initializing */
255 	uint64_t	vdev_initialize_bytes_est;
256 	uint64_t	vdev_initialize_bytes_done;
257 	time_t		vdev_initialize_action_time;	/* start and end time */
258 
259 	/* for limiting outstanding I/Os */
260 	kmutex_t	vdev_initialize_io_lock;
261 	kcondvar_t	vdev_initialize_io_cv;
262 	uint64_t	vdev_initialize_inflight;
263 
264 	/*
265 	 * Values stored in the config for an indirect or removing vdev.
266 	 */
267 	vdev_indirect_config_t	vdev_indirect_config;
268 
269 	/*
270 	 * The vdev_indirect_rwlock protects the vdev_indirect_mapping
271 	 * pointer from changing on indirect vdevs (when it is condensed).
272 	 * Note that removing (not yet indirect) vdevs have different
273 	 * access patterns (the mapping is not accessed from open context,
274 	 * e.g. from zio_read) and locking strategy (e.g. svr_lock).
275 	 */
276 	krwlock_t vdev_indirect_rwlock;
277 	vdev_indirect_mapping_t *vdev_indirect_mapping;
278 	vdev_indirect_births_t *vdev_indirect_births;
279 
280 	/*
281 	 * In memory data structures used to manage the obsolete sm, for
282 	 * indirect or removing vdevs.
283 	 *
284 	 * The vdev_obsolete_segments is the in-core record of the segments
285 	 * that are no longer referenced anywhere in the pool (due to
286 	 * being freed or remapped and not referenced by any snapshots).
287 	 * During a sync, segments are added to vdev_obsolete_segments
288 	 * via vdev_indirect_mark_obsolete(); at the end of each sync
289 	 * pass, this is appended to vdev_obsolete_sm via
290 	 * vdev_indirect_sync_obsolete().  The vdev_obsolete_lock
291 	 * protects against concurrent modifications of vdev_obsolete_segments
292 	 * from multiple zio threads.
293 	 */
294 	kmutex_t	vdev_obsolete_lock;
295 	range_tree_t	*vdev_obsolete_segments;
296 	space_map_t	*vdev_obsolete_sm;
297 
298 	/*
299 	 * The queue depth parameters determine how many async writes are
300 	 * still pending (i.e. allocated but not yet issued to disk) per
301 	 * top-level (vdev_async_write_queue_depth) and the maximum allowed
302 	 * (vdev_max_async_write_queue_depth). These values only apply to
303 	 * top-level vdevs.
304 	 */
305 	uint64_t	vdev_async_write_queue_depth;
306 	uint64_t	vdev_max_async_write_queue_depth;
307 
308 	/*
309 	 * Leaf vdev state.
310 	 */
311 	range_tree_t	*vdev_dtl[DTL_TYPES]; /* dirty time logs	*/
312 	space_map_t	*vdev_dtl_sm;	/* dirty time log space map	*/
313 	txg_node_t	vdev_dtl_node;	/* per-txg dirty DTL linkage	*/
314 	uint64_t	vdev_dtl_object; /* DTL object			*/
315 	uint64_t	vdev_psize;	/* physical device capacity	*/
316 	uint64_t	vdev_wholedisk;	/* true if this is a whole disk */
317 	uint64_t	vdev_offline;	/* persistent offline state	*/
318 	uint64_t	vdev_faulted;	/* persistent faulted state	*/
319 	uint64_t	vdev_degraded;	/* persistent degraded state	*/
320 	uint64_t	vdev_removed;	/* persistent removed state	*/
321 	uint64_t	vdev_resilver_txg; /* persistent resilvering state */
322 	uint64_t	vdev_nparity;	/* number of parity devices for raidz */
323 	char		*vdev_path;	/* vdev path (if any)		*/
324 	char		*vdev_devid;	/* vdev devid (if any)		*/
325 	char		*vdev_physpath;	/* vdev device path (if any)	*/
326 	char		*vdev_fru;	/* physical FRU location	*/
327 	uint64_t	vdev_not_present; /* not present during import	*/
328 	uint64_t	vdev_unspare;	/* unspare when resilvering done */
329 	boolean_t	vdev_nowritecache; /* true if flushwritecache failed */
330 	boolean_t	vdev_checkremove; /* temporary online test	*/
331 	boolean_t	vdev_forcefault; /* force online fault		*/
332 	boolean_t	vdev_splitting;	/* split or repair in progress  */
333 	boolean_t	vdev_delayed_close; /* delayed device close?	*/
334 	boolean_t	vdev_tmpoffline; /* device taken offline temporarily? */
335 	boolean_t	vdev_detached;	/* device detached?		*/
336 	boolean_t	vdev_cant_read;	/* vdev is failing all reads	*/
337 	boolean_t	vdev_cant_write; /* vdev is failing all writes	*/
338 	boolean_t	vdev_isspare;	/* was a hot spare		*/
339 	boolean_t	vdev_isl2cache;	/* was a l2cache device		*/
340 	vdev_queue_t	vdev_queue;	/* I/O deadline schedule queue	*/
341 	vdev_cache_t	vdev_cache;	/* physical block cache		*/
342 	spa_aux_vdev_t	*vdev_aux;	/* for l2cache and spares vdevs	*/
343 	zio_t		*vdev_probe_zio; /* root of current probe	*/
344 	vdev_aux_t	vdev_label_aux;	/* on-disk aux state		*/
345 	uint64_t	vdev_leaf_zap;
346 
347 	/*
348 	 * For DTrace to work in userland (libzpool) context, these fields must
349 	 * remain at the end of the structure.  DTrace will use the kernel's
350 	 * CTF definition for 'struct vdev', and since the size of a kmutex_t is
351 	 * larger in userland, the offsets for the rest of the fields would be
352 	 * incorrect.
353 	 */
354 	kmutex_t	vdev_dtl_lock;	/* vdev_dtl_{map,resilver}	*/
355 	kmutex_t	vdev_stat_lock;	/* vdev_stat			*/
356 	kmutex_t	vdev_probe_lock; /* protects vdev_probe_zio	*/
357 };
358 
359 #define	VDEV_RAIDZ_MAXPARITY	3
360 
361 #define	VDEV_PAD_SIZE		(8 << 10)
362 /* 2 padding areas (vl_pad1 and vl_pad2) to skip */
363 #define	VDEV_SKIP_SIZE		VDEV_PAD_SIZE * 2
364 #define	VDEV_PHYS_SIZE		(112 << 10)
365 #define	VDEV_UBERBLOCK_RING	(128 << 10)
366 
367 /* The largest uberblock we support is 8k. */
368 #define	MAX_UBERBLOCK_SHIFT (13)
369 #define	VDEV_UBERBLOCK_SHIFT(vd)	\
370 	MIN(MAX((vd)->vdev_top->vdev_ashift, UBERBLOCK_SHIFT), \
371 	    MAX_UBERBLOCK_SHIFT)
372 #define	VDEV_UBERBLOCK_COUNT(vd)	\
373 	(VDEV_UBERBLOCK_RING >> VDEV_UBERBLOCK_SHIFT(vd))
374 #define	VDEV_UBERBLOCK_OFFSET(vd, n)	\
375 	offsetof(vdev_label_t, vl_uberblock[(n) << VDEV_UBERBLOCK_SHIFT(vd)])
376 #define	VDEV_UBERBLOCK_SIZE(vd)		(1ULL << VDEV_UBERBLOCK_SHIFT(vd))
377 
378 typedef struct vdev_phys {
379 	char		vp_nvlist[VDEV_PHYS_SIZE - sizeof (zio_eck_t)];
380 	zio_eck_t	vp_zbt;
381 } vdev_phys_t;
382 
383 typedef struct vdev_label {
384 	char		vl_pad1[VDEV_PAD_SIZE];			/*  8K */
385 	char		vl_pad2[VDEV_PAD_SIZE];			/*  8K */
386 	vdev_phys_t	vl_vdev_phys;				/* 112K	*/
387 	char		vl_uberblock[VDEV_UBERBLOCK_RING];	/* 128K	*/
388 } vdev_label_t;							/* 256K total */
389 
390 /*
391  * vdev_dirty() flags
392  */
393 #define	VDD_METASLAB	0x01
394 #define	VDD_DTL		0x02
395 
396 /* Offset of embedded boot loader region on each label */
397 #define	VDEV_BOOT_OFFSET	(2 * sizeof (vdev_label_t))
398 /*
399  * Size of embedded boot loader region on each label.
400  * The total size of the first two labels plus the boot area is 4MB.
401  */
402 #define	VDEV_BOOT_SIZE		(7ULL << 19)			/* 3.5M */
403 
404 /*
405  * Size of label regions at the start and end of each leaf device.
406  */
407 #define	VDEV_LABEL_START_SIZE	(2 * sizeof (vdev_label_t) + VDEV_BOOT_SIZE)
408 #define	VDEV_LABEL_END_SIZE	(2 * sizeof (vdev_label_t))
409 #define	VDEV_LABELS		4
410 #define	VDEV_BEST_LABEL		VDEV_LABELS
411 
412 #define	VDEV_ALLOC_LOAD		0
413 #define	VDEV_ALLOC_ADD		1
414 #define	VDEV_ALLOC_SPARE	2
415 #define	VDEV_ALLOC_L2CACHE	3
416 #define	VDEV_ALLOC_ROOTPOOL	4
417 #define	VDEV_ALLOC_SPLIT	5
418 #define	VDEV_ALLOC_ATTACH	6
419 
420 /*
421  * Allocate or free a vdev
422  */
423 extern vdev_t *vdev_alloc_common(spa_t *spa, uint_t id, uint64_t guid,
424     vdev_ops_t *ops);
425 extern int vdev_alloc(spa_t *spa, vdev_t **vdp, nvlist_t *config,
426     vdev_t *parent, uint_t id, int alloctype);
427 extern void vdev_free(vdev_t *vd);
428 
429 /*
430  * Add or remove children and parents
431  */
432 extern void vdev_add_child(vdev_t *pvd, vdev_t *cvd);
433 extern void vdev_remove_child(vdev_t *pvd, vdev_t *cvd);
434 extern void vdev_compact_children(vdev_t *pvd);
435 extern vdev_t *vdev_add_parent(vdev_t *cvd, vdev_ops_t *ops);
436 extern void vdev_remove_parent(vdev_t *cvd);
437 
438 /*
439  * vdev sync load and sync
440  */
441 extern boolean_t vdev_log_state_valid(vdev_t *vd);
442 extern int vdev_load(vdev_t *vd);
443 extern int vdev_dtl_load(vdev_t *vd);
444 extern void vdev_sync(vdev_t *vd, uint64_t txg);
445 extern void vdev_sync_done(vdev_t *vd, uint64_t txg);
446 extern void vdev_dirty(vdev_t *vd, int flags, void *arg, uint64_t txg);
447 extern void vdev_dirty_leaves(vdev_t *vd, int flags, uint64_t txg);
448 
449 /*
450  * Available vdev types.
451  */
452 extern vdev_ops_t vdev_root_ops;
453 extern vdev_ops_t vdev_mirror_ops;
454 extern vdev_ops_t vdev_replacing_ops;
455 extern vdev_ops_t vdev_raidz_ops;
456 extern vdev_ops_t vdev_disk_ops;
457 extern vdev_ops_t vdev_file_ops;
458 extern vdev_ops_t vdev_missing_ops;
459 extern vdev_ops_t vdev_hole_ops;
460 extern vdev_ops_t vdev_spare_ops;
461 extern vdev_ops_t vdev_indirect_ops;
462 
463 /*
464  * Common size functions
465  */
466 extern void vdev_default_xlate(vdev_t *vd, const range_seg_t *in,
467     range_seg_t *out);
468 extern uint64_t vdev_default_asize(vdev_t *vd, uint64_t psize);
469 extern uint64_t vdev_get_min_asize(vdev_t *vd);
470 extern void vdev_set_min_asize(vdev_t *vd);
471 
472 /*
473  * Global variables
474  */
475 extern int vdev_standard_sm_blksz;
476 /* zdb uses this tunable, so it must be declared here to make lint happy. */
477 extern int zfs_vdev_cache_size;
478 
479 /*
480  * Functions from vdev_indirect.c
481  */
482 extern void vdev_indirect_sync_obsolete(vdev_t *vd, dmu_tx_t *tx);
483 extern boolean_t vdev_indirect_should_condense(vdev_t *vd);
484 extern void spa_condense_indirect_start_sync(vdev_t *vd, dmu_tx_t *tx);
485 extern int vdev_obsolete_sm_object(vdev_t *vd);
486 extern boolean_t vdev_obsolete_counts_are_precise(vdev_t *vd);
487 
488 /*
489  * Other miscellaneous functions
490  */
491 int vdev_checkpoint_sm_object(vdev_t *vd);
492 
493 /*
494  * The vdev_buf_t is used to translate between zio_t and buf_t, and back again.
495  */
496 typedef struct vdev_buf {
497 	buf_t	vb_buf;		/* buffer that describes the io */
498 	zio_t	*vb_io;		/* pointer back to the original zio_t */
499 } vdev_buf_t;
500 
501 #ifdef	__cplusplus
502 }
503 #endif
504 
505 #endif	/* _SYS_VDEV_IMPL_H */
506