sys/dmu_impl.h File Reference

This is the locking strategy for the DMU. More...

#include <sys/txg_impl.h>
#include <sys/zio.h>
#include <sys/dnode.h>
#include <sys/kstat.h>
#include <sys/zfs_context.h>
#include <sys/zfs_ioctl.h>
#include <sys/zfs_ioctl.h>

Include dependency graph for dmu_impl.h:

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Go to the source code of this file.

Data Structures
struct	dmu_xuio
struct	xuio_stats
struct	dmu_sendarg
Defines
#define	XUIOSTAT_INCR(stat, val)   atomic_add_64(&xuio_stats.stat.value.ui64, (val))
#define	XUIOSTAT_BUMP(stat)   XUIOSTAT_INCR(stat, 1)
Typedefs
typedef struct dmu_xuio	dmu_xuio_t
typedef struct xuio_stats	xuio_stats_t
typedef struct dmu_sendarg	dmu_sendarg_t
Enumerations
enum	dmu_pendop_t { PENDING_NONE, PENDING_FREE, PENDING_FREEOBJECTS }
Variables
static xuio_stats_t	xuio_stats

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Detailed Description

This is the locking strategy for the DMU.

Numbers in parenthesis are cases that use that lock order, referenced below:

• ARC is self-contained
• bplist is self-contained
• refcount is self-contained
• txg is self-contained (hopefully!)
• zst_lock
• zf_rwlock

Todo:

try to improve evicting path?

dp_config_rwlock > os_obj_lock > dn_struct_rwlock > dn_dbufs_mtx > hash_mutexes > db_mtx > dd_lock > leafs

dp_config_rwlock

• must be held before: everything
• protects dd namespace changes
• protects property changes globally
• held from:
  • dsl_dir_open/r:
  • dsl_dir_create_sync/w:
  • dsl_dir_sync_destroy/w:
  • dsl_dir_rename_sync/w:
  • dsl_prop_changed_notify/r:

os_obj_lock

• must be held before: everything except dp_config_rwlock
• protects os_obj_next
• held from:
  • dmu_object_alloc: dn_dbufs_mtx, db_mtx, hash_mutexes, dn_struct_rwlock

dn_struct_rwlock

• must be held before: everything except dp_config_rwlock and os_obj_lock
• protects structure of dnode (eg. nlevels)
  • db_blkptr can change when syncing out change to nlevels
  • dn_maxblkid
  • dn_nlevels
  • dn_*blksz*
  • phys nlevels, maxblkid, physical blkptr_t's (?)
• held from:
  • callers of dbuf_read_impl, dbuf_hold[_impl], dbuf_prefetch
  • dmu_object_info_from_dnode: dn_dirty_mtx (dn_datablksz)
  • dmu_tx_count_free:
  • dbuf_read_impl: db_mtx, dmu_zfetch()
  • dmu_zfetch: zf_rwlock/r, zst_lock, dbuf_prefetch()
  • dbuf_new_size: db_mtx
  • dbuf_dirty: db_mtx
  • dbuf_findbp: (callers, phys? - the real need)
  • dbuf_create: dn_dbufs_mtx, hash_mutexes, db_mtx (phys?)
  • dbuf_prefetch: dn_dirty_mtx, hash_mutexes, db_mtx, dn_dbufs_mtx
  • dbuf_hold_impl: hash_mutexes, db_mtx, dn_dbufs_mtx, dbuf_findbp()
  • dnode_sync/w (increase_indirection): db_mtx (phys)
  • dnode_set_blksz/w: dn_dbufs_mtx (dn_*blksz*)
  • dnode_new_blkid/w: (dn_maxblkid)
  • dnode_free_range/w: dn_dirty_mtx (dn_maxblkid)
  • dnode_next_offset: (phys)

dn_dbufs_mtx

• must be held before: db_mtx, hash_mutexes
• protects:
  • dn_dbufs
  • dn_evicted
• held from:
  • dmu_evict_user: db_mtx (dn_dbufs)
  • dbuf_free_range: db_mtx (dn_dbufs)
  • dbuf_remove_ref: db_mtx, callees: dbuf_hash_remove: hash_mutexes, db_mtx
  • dbuf_create: hash_mutexes, db_mtx (dn_dbufs)
  • dnode_set_blksz: (dn_dbufs)

hash_mutexes (global)

• must be held before: db_mtx
• protects dbuf_hash_table (global) and db_hash_next
• held from:
  • dbuf_find: db_mtx
  • dbuf_hash_insert: db_mtx
  • dbuf_hash_remove: db_mtx

db_mtx (meta-leaf)

• must be held before: dn_mtx, dn_dirty_mtx, dd_lock (leaf mutexes)
• protects:
  • db_state
  • db_holds
  • db_buf
  • db_changed
  • db_data_pending
  • db_dirtied
  • db_link
  • db_dirty_node (??)
  • db_dirtycnt
  • db_d.*
  • db.*
• held from:
  • dbuf_dirty: dn_mtx, dn_dirty_mtx
  • dbuf_dirty->dsl_dir_willuse_space: dd_lock
  • dbuf_dirty->dbuf_new_block->dsl_dataset_block_freeable: dd_lock
  • dbuf_undirty: dn_dirty_mtx (db_d)
  • dbuf_write_done: dn_dirty_mtx (db_state)
  • dbuf_*
  • dmu_buf_update_user: none (db_d)
  • dmu_evict_user: none (db_d) (maybe can eliminate)
  • dbuf_find: none (db_holds)
  • dbuf_hash_insert: none (db_holds)
  • dmu_buf_read_array_impl: none (db_state, db_changed)
  • dmu_sync: none (db_dirty_node, db_d)
  • dnode_reallocate: none (db)

dn_mtx (leaf)

• protects:
  • dn_dirty_dbufs
  • dn_ranges
  • phys accounting
  • dn_allocated_txg
  • dn_free_txg
  • dn_assigned_txg
  • dd_assigned_tx
  • dn_notxholds
  • dn_dirtyctx
  • dn_dirtyctx_firstset
  • (dn_phys copy fields?)
  • (dn_phys contents?)
• held from:
  • dnode_*
  • dbuf_dirty: none
  • dbuf_sync: none (phys accounting)
  • dbuf_undirty: none (dn_ranges, dn_dirty_dbufs)
  • dbuf_write_done: none (phys accounting)
  • dmu_object_info_from_dnode: none (accounting)
  • dmu_tx_commit: none
  • dmu_tx_hold_object_impl: none
  • dmu_tx_try_assign: dn_notxholds(cv)
  • dmu_tx_unassign: none

dd_lock

• must be held before:
  • ds_lock
  • ancestors' dd_lock
• protects:
  • dd_prop_cbs
  • dd_sync_*
  • dd_used_bytes
  • dd_tempreserved
  • dd_space_towrite
  • dd_myname
  • dd_phys accounting?
• held from:
  • dsl_dir_*
  • dsl_prop_changed_notify: none (dd_prop_cbs)
  • dsl_prop_register: none (dd_prop_cbs)
  • dsl_prop_unregister: none (dd_prop_cbs)
  • dsl_dataset_block_freeable: none (dd_sync_*)

os_lock (leaf)

• protects:
  • os_dirty_dnodes
  • os_free_dnodes
  • os_dnodes
  • os_downgraded_dbufs
  • dn_dirtyblksz
  • dn_dirty_link
• held from:
  • dnode_create: none (os_dnodes)
  • dnode_destroy: none (os_dnodes)
  • dnode_setdirty: none (dn_dirtyblksz, os_*_dnodes)
  • dnode_free: none (dn_dirtyblksz, os_*_dnodes)

ds_lock

• protects:
  • ds_objset
  • ds_open_refcount
  • ds_snapname
  • ds_phys accounting
  • ds_phys userrefs zapobj
  • ds_reserved
• held from:
  • dsl_dataset_*

dr_mtx (leaf)

• protects:
  • dr_children
• held from:
  • dbuf_dirty
  • dbuf_undirty
  • dbuf_sync_indirect
  • dnode_new_blkid

Definition in file dmu_impl.h.

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Define Documentation

#define XUIOSTAT_BUMP

(

stat

)

XUIOSTAT_INCR(stat, 1)

Definition at line 271 of file dmu_impl.h.

#define XUIOSTAT_INCR	(		stat,
			val
	)		atomic_add_64(&xuio_stats.stat.value.ui64, (val))

Definition at line 269 of file dmu_impl.h.

---

Typedef Documentation

typedef struct dmu_sendarg dmu_sendarg_t

typedef struct dmu_xuio dmu_xuio_t

typedef struct xuio_stats xuio_stats_t

---

Enumeration Type Documentation

enum dmu_pendop_t

Enumerator:

PENDING_NONE
PENDING_FREE
PENDING_FREEOBJECTS

Definition at line 279 of file dmu_impl.h.

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Variable Documentation

xuio_stats_t xuio_stats [static]

Initial value:

 {
        { "onloan_read_buf",    KSTAT_DATA_UINT64 },
        { "onloan_write_buf",   KSTAT_DATA_UINT64 },
        { "read_buf_copied",    KSTAT_DATA_UINT64 },
        { "read_buf_nocopy",    KSTAT_DATA_UINT64 },
        { "write_buf_copied",   KSTAT_DATA_UINT64 },
        { "write_buf_nocopy",   KSTAT_DATA_UINT64 }
}

Definition at line 260 of file dmu_impl.h.