FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/include/sys/dnode.h

     /*
      * CDDL HEADER START
      *
      * The contents of this file are subject to the terms of the
      * Common Development and Distribution License (the "License").
      * You may not use this file except in compliance with the License.
      *
      * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      * or https://opensource.org/licenses/CDDL-1.0.
     * See the License for the specific language governing permissions
     * and limitations under the License.
     *
     * When distributing Covered Code, include this CDDL HEADER in each
     * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     * If applicable, add the following below this CDDL HEADER, with the
     * fields enclosed by brackets "[]" replaced with your own identifying
     * information: Portions Copyright [yyyy] [name of copyright owner]
     *
     * CDDL HEADER END
     */
    /*
     * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
     * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
     * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
     */
    
    #ifndef _SYS_DNODE_H
    #define _SYS_DNODE_H
    
    #include <sys/zfs_context.h>
    #include <sys/avl.h>
    #include <sys/spa.h>
    #include <sys/txg.h>
    #include <sys/zio.h>
    #include <sys/zfs_refcount.h>
    #include <sys/dmu_zfetch.h>
    #include <sys/zrlock.h>
    #include <sys/multilist.h>
    #include <sys/wmsum.h>
    
    #ifdef  __cplusplus
    extern "C" {
    #endif
    
    /*
     * dnode_hold() flags.
     */
    #define DNODE_MUST_BE_ALLOCATED 1
    #define DNODE_MUST_BE_FREE      2
    #define DNODE_DRY_RUN           4
    
    /*
     * dnode_next_offset() flags.
     */
    #define DNODE_FIND_HOLE         1
    #define DNODE_FIND_BACKWARDS    2
    #define DNODE_FIND_HAVELOCK     4
    
    /*
     * Fixed constants.
     */
    #define DNODE_SHIFT             9       /* 512 bytes */
    #define DN_MIN_INDBLKSHIFT      12      /* 4k */
    /*
     * If we ever increase this value beyond 20, we need to revisit all logic that
     * does x << level * ebps to handle overflow.  With a 1M indirect block size,
     * 4 levels of indirect blocks would not be able to guarantee addressing an
     * entire object, so 5 levels will be used, but 5 * (20 - 7) = 65.
     */
    #define DN_MAX_INDBLKSHIFT      17      /* 128k */
    #define DNODE_BLOCK_SHIFT       14      /* 16k */
    #define DNODE_CORE_SIZE         64      /* 64 bytes for dnode sans blkptrs */
    #define DN_MAX_OBJECT_SHIFT     48      /* 256 trillion (zfs_fid_t limit) */
    #define DN_MAX_OFFSET_SHIFT     64      /* 2^64 bytes in a dnode */
    
    /*
     * dnode id flags
     *
     * Note: a file will never ever have its ids moved from bonus->spill
     */
    #define DN_ID_CHKED_BONUS       0x1
    #define DN_ID_CHKED_SPILL       0x2
    #define DN_ID_OLD_EXIST         0x4
    #define DN_ID_NEW_EXIST         0x8
    
    /*
     * Derived constants.
     */
    #define DNODE_MIN_SIZE          (1 << DNODE_SHIFT)
    #define DNODE_MAX_SIZE          (1 << DNODE_BLOCK_SHIFT)
    #define DNODE_BLOCK_SIZE        (1 << DNODE_BLOCK_SHIFT)
    #define DNODE_MIN_SLOTS         (DNODE_MIN_SIZE >> DNODE_SHIFT)
    #define DNODE_MAX_SLOTS         (DNODE_MAX_SIZE >> DNODE_SHIFT)
    #define DN_BONUS_SIZE(dnsize)   ((dnsize) - DNODE_CORE_SIZE - \
            (1 << SPA_BLKPTRSHIFT))
    #define DN_SLOTS_TO_BONUSLEN(slots)     DN_BONUS_SIZE((slots) << DNODE_SHIFT)
    #define DN_OLD_MAX_BONUSLEN     (DN_BONUS_SIZE(DNODE_MIN_SIZE))
    #define DN_MAX_NBLKPTR  ((DNODE_MIN_SIZE - DNODE_CORE_SIZE) >> SPA_BLKPTRSHIFT)
    #define DN_MAX_OBJECT   (1ULL << DN_MAX_OBJECT_SHIFT)
   #define DN_ZERO_BONUSLEN        (DN_BONUS_SIZE(DNODE_MAX_SIZE) + 1)
   #define DN_KILL_SPILLBLK (1)
   
   #define DN_SLOT_UNINIT          ((void *)NULL)  /* Uninitialized */
   #define DN_SLOT_FREE            ((void *)1UL)   /* Free slot */
   #define DN_SLOT_ALLOCATED       ((void *)2UL)   /* Allocated slot */
   #define DN_SLOT_INTERIOR        ((void *)3UL)   /* Interior allocated slot */
   #define DN_SLOT_IS_PTR(dn)      ((void *)dn > DN_SLOT_INTERIOR)
   #define DN_SLOT_IS_VALID(dn)    ((void *)dn != NULL)
   
   #define DNODES_PER_BLOCK_SHIFT  (DNODE_BLOCK_SHIFT - DNODE_SHIFT)
   #define DNODES_PER_BLOCK        (1ULL << DNODES_PER_BLOCK_SHIFT)
   
   /*
    * This is inaccurate if the indblkshift of the particular object is not the
    * max.  But it's only used by userland to calculate the zvol reservation.
    */
   #define DNODES_PER_LEVEL_SHIFT  (DN_MAX_INDBLKSHIFT - SPA_BLKPTRSHIFT)
   #define DNODES_PER_LEVEL        (1ULL << DNODES_PER_LEVEL_SHIFT)
   
   #define DN_MAX_LEVELS   (DIV_ROUND_UP(DN_MAX_OFFSET_SHIFT - SPA_MINBLOCKSHIFT, \
           DN_MIN_INDBLKSHIFT - SPA_BLKPTRSHIFT) + 1)
   
   #define DN_BONUS(dnp)   ((void*)((dnp)->dn_bonus + \
           (((dnp)->dn_nblkptr - 1) * sizeof (blkptr_t))))
   #define DN_MAX_BONUS_LEN(dnp) \
           ((dnp->dn_flags & DNODE_FLAG_SPILL_BLKPTR) ? \
           (uint8_t *)DN_SPILL_BLKPTR(dnp) - (uint8_t *)DN_BONUS(dnp) : \
           (uint8_t *)(dnp + (dnp->dn_extra_slots + 1)) - (uint8_t *)DN_BONUS(dnp))
   
   #define DN_USED_BYTES(dnp) (((dnp)->dn_flags & DNODE_FLAG_USED_BYTES) ? \
           (dnp)->dn_used : (dnp)->dn_used << SPA_MINBLOCKSHIFT)
   
   #define EPB(blkshift, typeshift)        (1 << (blkshift - typeshift))
   
   struct dmu_buf_impl;
   struct objset;
   struct zio;
   
   enum dnode_dirtycontext {
           DN_UNDIRTIED,
           DN_DIRTY_OPEN,
           DN_DIRTY_SYNC
   };
   
   /* Is dn_used in bytes?  if not, it's in multiples of SPA_MINBLOCKSIZE */
   #define DNODE_FLAG_USED_BYTES                   (1 << 0)
   #define DNODE_FLAG_USERUSED_ACCOUNTED           (1 << 1)
   
   /* Does dnode have a SA spill blkptr in bonus? */
   #define DNODE_FLAG_SPILL_BLKPTR                 (1 << 2)
   
   /* User/Group/Project dnode accounting */
   #define DNODE_FLAG_USEROBJUSED_ACCOUNTED        (1 << 3)
   
   /*
    * This mask defines the set of flags which are "portable", meaning
    * that they can be preserved when doing a raw encrypted zfs send.
    * Flags included in this mask will be protected by AAD when the block
    * of dnodes is encrypted.
    */
   #define DNODE_CRYPT_PORTABLE_FLAGS_MASK         (DNODE_FLAG_SPILL_BLKPTR)
   
   /*
    * VARIABLE-LENGTH (LARGE) DNODES
    *
    * The motivation for variable-length dnodes is to eliminate the overhead
    * associated with using spill blocks.  Spill blocks are used to store
    * system attribute data (i.e. file metadata) that does not fit in the
    * dnode's bonus buffer. By allowing a larger bonus buffer area the use of
    * a spill block can be avoided.  Spill blocks potentially incur an
    * additional read I/O for every dnode in a dnode block. As a worst case
    * example, reading 32 dnodes from a 16k dnode block and all of the spill
    * blocks could issue 33 separate reads. Now suppose those dnodes have size
    * 1024 and therefore don't need spill blocks. Then the worst case number
    * of blocks read is reduced from 33 to two--one per dnode block.
    *
    * ZFS-on-Linux systems that make heavy use of extended attributes benefit
    * from this feature. In particular, ZFS-on-Linux supports the xattr=sa
    * dataset property which allows file extended attribute data to be stored
    * in the dnode bonus buffer as an alternative to the traditional
    * directory-based format. Workloads such as SELinux and the Lustre
    * distributed filesystem often store enough xattr data to force spill
    * blocks when xattr=sa is in effect. Large dnodes may therefore provide a
    * performance benefit to such systems. Other use cases that benefit from
    * this feature include files with large ACLs and symbolic links with long
    * target names.
    *
    * The size of a dnode may be a multiple of 512 bytes up to the size of a
    * dnode block (currently 16384 bytes). The dn_extra_slots field of the
    * on-disk dnode_phys_t structure describes the size of the physical dnode
    * on disk. The field represents how many "extra" dnode_phys_t slots a
    * dnode consumes in its dnode block. This convention results in a value of
    * 0 for 512 byte dnodes which preserves on-disk format compatibility with
    * older software which doesn't support large dnodes.
    *
    * Similarly, the in-memory dnode_t structure has a dn_num_slots field
    * to represent the total number of dnode_phys_t slots consumed on disk.
    * Thus dn->dn_num_slots is 1 greater than the corresponding
    * dnp->dn_extra_slots. This difference in convention was adopted
    * because, unlike on-disk structures, backward compatibility is not a
    * concern for in-memory objects, so we used a more natural way to
    * represent size for a dnode_t.
    *
    * The default size for newly created dnodes is determined by the value of
    * the "dnodesize" dataset property. By default the property is set to
    * "legacy" which is compatible with older software. Setting the property
    * to "auto" will allow the filesystem to choose the most suitable dnode
    * size. Currently this just sets the default dnode size to 1k, but future
    * code improvements could dynamically choose a size based on observed
    * workload patterns. Dnodes of varying sizes can coexist within the same
    * dataset and even within the same dnode block.
    */
   
   typedef struct dnode_phys {
           uint8_t dn_type;                /* dmu_object_type_t */
           uint8_t dn_indblkshift;         /* ln2(indirect block size) */
           uint8_t dn_nlevels;             /* 1=dn_blkptr->data blocks */
           uint8_t dn_nblkptr;             /* length of dn_blkptr */
           uint8_t dn_bonustype;           /* type of data in bonus buffer */
           uint8_t dn_checksum;            /* ZIO_CHECKSUM type */
           uint8_t dn_compress;            /* ZIO_COMPRESS type */
           uint8_t dn_flags;               /* DNODE_FLAG_* */
           uint16_t dn_datablkszsec;       /* data block size in 512b sectors */
           uint16_t dn_bonuslen;           /* length of dn_bonus */
           uint8_t dn_extra_slots;         /* # of subsequent slots consumed */
           uint8_t dn_pad2[3];
   
           /* accounting is protected by dn_dirty_mtx */
           uint64_t dn_maxblkid;           /* largest allocated block ID */
           uint64_t dn_used;               /* bytes (or sectors) of disk space */
   
           /*
            * Both dn_pad2 and dn_pad3 are protected by the block's MAC. This
            * allows us to protect any fields that might be added here in the
            * future. In either case, developers will want to check
            * zio_crypt_init_uios_dnode() and zio_crypt_do_dnode_hmac_updates()
            * to ensure the new field is being protected and updated properly.
            */
           uint64_t dn_pad3[4];
   
           /*
            * The tail region is 448 bytes for a 512 byte dnode, and
            * correspondingly larger for larger dnode sizes. The spill
            * block pointer, when present, is always at the end of the tail
            * region. There are three ways this space may be used, using
            * a 512 byte dnode for this diagram:
            *
            * 0       64      128     192     256     320     384     448 (offset)
            * +---------------+---------------+---------------+-------+
            * | dn_blkptr[0]  | dn_blkptr[1]  | dn_blkptr[2]  | /     |
            * +---------------+---------------+---------------+-------+
            * | dn_blkptr[0]  | dn_bonus[0..319]                      |
            * +---------------+-----------------------+---------------+
            * | dn_blkptr[0]  | dn_bonus[0..191]      | dn_spill      |
            * +---------------+-----------------------+---------------+
            */
           union {
                   blkptr_t dn_blkptr[1+DN_OLD_MAX_BONUSLEN/sizeof (blkptr_t)];
                   struct {
                           blkptr_t __dn_ignore1;
                           uint8_t dn_bonus[DN_OLD_MAX_BONUSLEN];
                   };
                   struct {
                           blkptr_t __dn_ignore2;
                           uint8_t __dn_ignore3[DN_OLD_MAX_BONUSLEN -
                               sizeof (blkptr_t)];
                           blkptr_t dn_spill;
                   };
           };
   } dnode_phys_t;
   
   #define DN_SPILL_BLKPTR(dnp)    ((blkptr_t *)((char *)(dnp) + \
           (((dnp)->dn_extra_slots + 1) << DNODE_SHIFT) - (1 << SPA_BLKPTRSHIFT)))
   
   struct dnode {
           /*
            * Protects the structure of the dnode, including the number of levels
            * of indirection (dn_nlevels), dn_maxblkid, and dn_next_*
            */
           krwlock_t dn_struct_rwlock;
   
           /* Our link on dn_objset->os_dnodes list; protected by os_lock.  */
           list_node_t dn_link;
   
           /* immutable: */
           struct objset *dn_objset;
           uint64_t dn_object;
           struct dmu_buf_impl *dn_dbuf;
           struct dnode_handle *dn_handle;
           dnode_phys_t *dn_phys; /* pointer into dn->dn_dbuf->db.db_data */
   
           /*
            * Copies of stuff in dn_phys.  They're valid in the open
            * context (eg. even before the dnode is first synced).
            * Where necessary, these are protected by dn_struct_rwlock.
            */
           dmu_object_type_t dn_type;      /* object type */
           uint16_t dn_bonuslen;           /* bonus length */
           uint8_t dn_bonustype;           /* bonus type */
           uint8_t dn_nblkptr;             /* number of blkptrs (immutable) */
           uint8_t dn_checksum;            /* ZIO_CHECKSUM type */
           uint8_t dn_compress;            /* ZIO_COMPRESS type */
           uint8_t dn_nlevels;
           uint8_t dn_indblkshift;
           uint8_t dn_datablkshift;        /* zero if blksz not power of 2! */
           uint8_t dn_moved;               /* Has this dnode been moved? */
           uint16_t dn_datablkszsec;       /* in 512b sectors */
           uint32_t dn_datablksz;          /* in bytes */
           uint64_t dn_maxblkid;
           uint8_t dn_next_type[TXG_SIZE];
           uint8_t dn_num_slots;           /* metadnode slots consumed on disk */
           uint8_t dn_next_nblkptr[TXG_SIZE];
           uint8_t dn_next_nlevels[TXG_SIZE];
           uint8_t dn_next_indblkshift[TXG_SIZE];
           uint8_t dn_next_bonustype[TXG_SIZE];
           uint8_t dn_rm_spillblk[TXG_SIZE];       /* for removing spill blk */
           uint16_t dn_next_bonuslen[TXG_SIZE];
           uint32_t dn_next_blksz[TXG_SIZE];       /* next block size in bytes */
           uint64_t dn_next_maxblkid[TXG_SIZE];    /* next maxblkid in bytes */
   
           /* protected by dn_dbufs_mtx; declared here to fill 32-bit hole */
           uint32_t dn_dbufs_count;        /* count of dn_dbufs */
   
           /* protected by os_lock: */
           multilist_node_t dn_dirty_link[TXG_SIZE]; /* next on dataset's dirty */
   
           /* protected by dn_mtx: */
           kmutex_t dn_mtx;
           list_t dn_dirty_records[TXG_SIZE];
           struct range_tree *dn_free_ranges[TXG_SIZE];
           uint64_t dn_allocated_txg;
           uint64_t dn_free_txg;
           uint64_t dn_assigned_txg;
           uint64_t dn_dirty_txg;                  /* txg dnode was last dirtied */
           kcondvar_t dn_notxholds;
           kcondvar_t dn_nodnholds;
           enum dnode_dirtycontext dn_dirtyctx;
           const void *dn_dirtyctx_firstset;       /* dbg: contents meaningless */
   
           /* protected by own devices */
           zfs_refcount_t dn_tx_holds;
           zfs_refcount_t dn_holds;
   
           kmutex_t dn_dbufs_mtx;
           /*
            * Descendent dbufs, ordered by dbuf_compare. Note that dn_dbufs
            * can contain multiple dbufs of the same (level, blkid) when a
            * dbuf is marked DB_EVICTING without being removed from
            * dn_dbufs. To maintain the avl invariant that there cannot be
            * duplicate entries, we order the dbufs by an arbitrary value -
            * their address in memory. This means that dn_dbufs cannot be used to
            * directly look up a dbuf. Instead, callers must use avl_walk, have
            * a reference to the dbuf, or look up a non-existent node with
            * db_state = DB_SEARCH (see dbuf_free_range for an example).
            */
           avl_tree_t dn_dbufs;
   
           /* protected by dn_struct_rwlock */
           struct dmu_buf_impl *dn_bonus;  /* bonus buffer dbuf */
   
           boolean_t dn_have_spill;        /* have spill or are spilling */
   
           /* parent IO for current sync write */
           zio_t *dn_zio;
   
           /* used in syncing context */
           uint64_t dn_oldused;    /* old phys used bytes */
           uint64_t dn_oldflags;   /* old phys dn_flags */
           uint64_t dn_olduid, dn_oldgid, dn_oldprojid;
           uint64_t dn_newuid, dn_newgid, dn_newprojid;
           int dn_id_flags;
   
           /* holds prefetch structure */
           struct zfetch   dn_zfetch;
   };
   
   /*
    * Since AVL already has embedded element counter, use dn_dbufs_count
    * only for dbufs not counted there (bonus buffers) and just add them.
    */
   #define DN_DBUFS_COUNT(dn)      ((dn)->dn_dbufs_count + \
       avl_numnodes(&(dn)->dn_dbufs))
   
   /*
    * We use this (otherwise unused) bit to indicate if the value of
    * dn_next_maxblkid[txgoff] is valid to use in dnode_sync().
    */
   #define DMU_NEXT_MAXBLKID_SET           (1ULL << 63)
   
   /*
    * Adds a level of indirection between the dbuf and the dnode to avoid
    * iterating descendent dbufs in dnode_move(). Handles are not allocated
    * individually, but as an array of child dnodes in dnode_hold_impl().
    */
   typedef struct dnode_handle {
           /* Protects dnh_dnode from modification by dnode_move(). */
           zrlock_t dnh_zrlock;
           dnode_t *dnh_dnode;
   } dnode_handle_t;
   
   typedef struct dnode_children {
           dmu_buf_user_t dnc_dbu;         /* User evict data */
           size_t dnc_count;               /* number of children */
           dnode_handle_t dnc_children[];  /* sized dynamically */
   } dnode_children_t;
   
   typedef struct free_range {
           avl_node_t fr_node;
           uint64_t fr_blkid;
           uint64_t fr_nblks;
   } free_range_t;
   
   void dnode_special_open(struct objset *dd, dnode_phys_t *dnp,
       uint64_t object, dnode_handle_t *dnh);
   void dnode_special_close(dnode_handle_t *dnh);
   
   void dnode_setbonuslen(dnode_t *dn, int newsize, dmu_tx_t *tx);
   void dnode_setbonus_type(dnode_t *dn, dmu_object_type_t, dmu_tx_t *tx);
   void dnode_rm_spill(dnode_t *dn, dmu_tx_t *tx);
   
   int dnode_hold(struct objset *dd, uint64_t object,
       const void *ref, dnode_t **dnp);
   int dnode_hold_impl(struct objset *dd, uint64_t object, int flag, int dn_slots,
       const void *ref, dnode_t **dnp);
   boolean_t dnode_add_ref(dnode_t *dn, const void *ref);
   void dnode_rele(dnode_t *dn, const void *ref);
   void dnode_rele_and_unlock(dnode_t *dn, const void *tag, boolean_t evicting);
   int dnode_try_claim(objset_t *os, uint64_t object, int slots);
   boolean_t dnode_is_dirty(dnode_t *dn);
   void dnode_setdirty(dnode_t *dn, dmu_tx_t *tx);
   void dnode_set_dirtyctx(dnode_t *dn, dmu_tx_t *tx, const void *tag);
   void dnode_sync(dnode_t *dn, dmu_tx_t *tx);
   void dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
       dmu_object_type_t bonustype, int bonuslen, int dn_slots, dmu_tx_t *tx);
   void dnode_reallocate(dnode_t *dn, dmu_object_type_t ot, int blocksize,
       dmu_object_type_t bonustype, int bonuslen, int dn_slots,
       boolean_t keep_spill, dmu_tx_t *tx);
   void dnode_free(dnode_t *dn, dmu_tx_t *tx);
   void dnode_byteswap(dnode_phys_t *dnp);
   void dnode_buf_byteswap(void *buf, size_t size);
   void dnode_verify(dnode_t *dn);
   int dnode_set_nlevels(dnode_t *dn, int nlevels, dmu_tx_t *tx);
   int dnode_set_blksz(dnode_t *dn, uint64_t size, int ibs, dmu_tx_t *tx);
   void dnode_free_range(dnode_t *dn, uint64_t off, uint64_t len, dmu_tx_t *tx);
   void dnode_diduse_space(dnode_t *dn, int64_t space);
   void dnode_new_blkid(dnode_t *dn, uint64_t blkid, dmu_tx_t *tx,
       boolean_t have_read, boolean_t force);
   uint64_t dnode_block_freed(dnode_t *dn, uint64_t blkid);
   void dnode_init(void);
   void dnode_fini(void);
   int dnode_next_offset(dnode_t *dn, int flags, uint64_t *off,
       int minlvl, uint64_t blkfill, uint64_t txg);
   void dnode_evict_dbufs(dnode_t *dn);
   void dnode_evict_bonus(dnode_t *dn);
   void dnode_free_interior_slots(dnode_t *dn);
   
   #define DNODE_IS_DIRTY(_dn)                                             \
           ((_dn)->dn_dirty_txg >= spa_syncing_txg((_dn)->dn_objset->os_spa))
   
   #define DNODE_LEVEL_IS_CACHEABLE(_dn, _level)                           \
           ((_dn)->dn_objset->os_primary_cache == ZFS_CACHE_ALL ||         \
           (((_level) > 0 || DMU_OT_IS_METADATA((_dn)->dn_type)) &&        \
           (_dn)->dn_objset->os_primary_cache == ZFS_CACHE_METADATA))
   
   /*
    * Used for dnodestats kstat.
    */
   typedef struct dnode_stats {
           /*
            * Number of failed attempts to hold a meta dnode dbuf.
            */
           kstat_named_t dnode_hold_dbuf_hold;
           /*
            * Number of failed attempts to read a meta dnode dbuf.
            */
           kstat_named_t dnode_hold_dbuf_read;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_ALLOCATED) was able
            * to hold the requested object number which was allocated.  This is
            * the common case when looking up any allocated object number.
            */
           kstat_named_t dnode_hold_alloc_hits;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_ALLOCATED) was not
            * able to hold the request object number because it was not allocated.
            */
           kstat_named_t dnode_hold_alloc_misses;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_ALLOCATED) was not
            * able to hold the request object number because the object number
            * refers to an interior large dnode slot.
            */
           kstat_named_t dnode_hold_alloc_interior;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_ALLOCATED) needed
            * to retry acquiring slot zrl locks due to contention.
            */
           kstat_named_t dnode_hold_alloc_lock_retry;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_ALLOCATED) did not
            * need to create the dnode because another thread did so after
            * dropping the read lock but before acquiring the write lock.
            */
           kstat_named_t dnode_hold_alloc_lock_misses;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_ALLOCATED) found
            * a free dnode instantiated by dnode_create() but not yet allocated
            * by dnode_allocate().
            */
           kstat_named_t dnode_hold_alloc_type_none;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_FREE) was able
            * to hold the requested range of free dnode slots.
            */
           kstat_named_t dnode_hold_free_hits;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_FREE) was not
            * able to hold the requested range of free dnode slots because
            * at least one slot was allocated.
            */
           kstat_named_t dnode_hold_free_misses;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_FREE) was not
            * able to hold the requested range of free dnode slots because
            * after acquiring the zrl lock at least one slot was allocated.
            */
           kstat_named_t dnode_hold_free_lock_misses;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_FREE) needed
            * to retry acquiring slot zrl locks due to contention.
            */
           kstat_named_t dnode_hold_free_lock_retry;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_FREE) requested
            * a range of dnode slots which were held by another thread.
            */
           kstat_named_t dnode_hold_free_refcount;
           /*
            * Number of times dnode_hold(..., DNODE_MUST_BE_FREE) requested
            * a range of dnode slots which would overflow the dnode_phys_t.
            */
           kstat_named_t dnode_hold_free_overflow;
           /*
            * Number of times dnode_free_interior_slots() needed to retry
            * acquiring a slot zrl lock due to contention.
            */
           kstat_named_t dnode_free_interior_lock_retry;
           /*
            * Number of new dnodes allocated by dnode_allocate().
            */
           kstat_named_t dnode_allocate;
           /*
            * Number of dnodes re-allocated by dnode_reallocate().
            */
           kstat_named_t dnode_reallocate;
           /*
            * Number of meta dnode dbufs evicted.
            */
           kstat_named_t dnode_buf_evict;
           /*
            * Number of times dmu_object_alloc*() reached the end of the existing
            * object ID chunk and advanced to a new one.
            */
           kstat_named_t dnode_alloc_next_chunk;
           /*
            * Number of times multiple threads attempted to allocate a dnode
            * from the same block of free dnodes.
            */
           kstat_named_t dnode_alloc_race;
           /*
            * Number of times dmu_object_alloc*() was forced to advance to the
            * next meta dnode dbuf due to an error from  dmu_object_next().
            */
           kstat_named_t dnode_alloc_next_block;
           /*
            * Statistics for tracking dnodes which have been moved.
            */
           kstat_named_t dnode_move_invalid;
           kstat_named_t dnode_move_recheck1;
           kstat_named_t dnode_move_recheck2;
           kstat_named_t dnode_move_special;
           kstat_named_t dnode_move_handle;
           kstat_named_t dnode_move_rwlock;
           kstat_named_t dnode_move_active;
   } dnode_stats_t;
   
   typedef struct dnode_sums {
           wmsum_t dnode_hold_dbuf_hold;
           wmsum_t dnode_hold_dbuf_read;
           wmsum_t dnode_hold_alloc_hits;
           wmsum_t dnode_hold_alloc_misses;
           wmsum_t dnode_hold_alloc_interior;
           wmsum_t dnode_hold_alloc_lock_retry;
           wmsum_t dnode_hold_alloc_lock_misses;
           wmsum_t dnode_hold_alloc_type_none;
           wmsum_t dnode_hold_free_hits;
           wmsum_t dnode_hold_free_misses;
           wmsum_t dnode_hold_free_lock_misses;
           wmsum_t dnode_hold_free_lock_retry;
           wmsum_t dnode_hold_free_refcount;
           wmsum_t dnode_hold_free_overflow;
           wmsum_t dnode_free_interior_lock_retry;
           wmsum_t dnode_allocate;
           wmsum_t dnode_reallocate;
           wmsum_t dnode_buf_evict;
           wmsum_t dnode_alloc_next_chunk;
           wmsum_t dnode_alloc_race;
           wmsum_t dnode_alloc_next_block;
           wmsum_t dnode_move_invalid;
           wmsum_t dnode_move_recheck1;
           wmsum_t dnode_move_recheck2;
           wmsum_t dnode_move_special;
           wmsum_t dnode_move_handle;
           wmsum_t dnode_move_rwlock;
           wmsum_t dnode_move_active;
   } dnode_sums_t;
   
   extern dnode_stats_t dnode_stats;
   extern dnode_sums_t dnode_sums;
   
   #define DNODE_STAT_INCR(stat, val) \
       wmsum_add(&dnode_sums.stat, (val))
   #define DNODE_STAT_BUMP(stat) \
       DNODE_STAT_INCR(stat, 1);
   
   #ifdef ZFS_DEBUG
   
   #define dprintf_dnode(dn, fmt, ...) do { \
           if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
           char __db_buf[32]; \
           uint64_t __db_obj = (dn)->dn_object; \
           if (__db_obj == DMU_META_DNODE_OBJECT) \
                   (void) strlcpy(__db_buf, "mdn", sizeof (__db_buf));     \
           else \
                   (void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
                       (u_longlong_t)__db_obj);\
           dprintf_ds((dn)->dn_objset->os_dsl_dataset, "obj=%s " fmt, \
               __db_buf, __VA_ARGS__); \
           } \
   } while (0)
   
   #define DNODE_VERIFY(dn)                dnode_verify(dn)
   #define FREE_VERIFY(db, start, end, tx) free_verify(db, start, end, tx)
   
   #else
   
   #define dprintf_dnode(db, fmt, ...)
   #define DNODE_VERIFY(dn)                ((void) sizeof ((uintptr_t)(dn)))
   #define FREE_VERIFY(db, start, end, tx)
   
   #endif
   
   #ifdef  __cplusplus
   }
   #endif
   
   #endif  /* _SYS_DNODE_H */

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