kernel/fs/zfs/sys/vdev_impl.h

   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 by net 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 */