initial commit
[freebsd-arm:freebsd-arm.git] / cddl / contrib / opensolaris / uts / common / fs / zfs / sys / dmu_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 2008 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25
26 #ifndef _SYS_DMU_IMPL_H
27 #define _SYS_DMU_IMPL_H
28
29 #include <sys/txg_impl.h>
30 #include <sys/zio.h>
31 #include <sys/dnode.h>
32 #include <sys/zfs_context.h>
33
34 #ifdef  __cplusplus
35 extern "C" {
36 #endif
37
38 /*
39  * This is the locking strategy for the DMU.  Numbers in parenthesis are
40  * cases that use that lock order, referenced below:
41  *
42  * ARC is self-contained
43  * bplist is self-contained
44  * refcount is self-contained
45  * txg is self-contained (hopefully!)
46  * zst_lock
47  * zf_rwlock
48  *
49  * XXX try to improve evicting path?
50  *
51  * dp_config_rwlock > os_obj_lock > dn_struct_rwlock >
52  *      dn_dbufs_mtx > hash_mutexes > db_mtx > dd_lock > leafs
53  *
54  * dp_config_rwlock
55  *    must be held before: everything
56  *    protects dd namespace changes
57  *    protects property changes globally
58  *    held from:
59  *      dsl_dir_open/r:
60  *      dsl_dir_create_sync/w:
61  *      dsl_dir_sync_destroy/w:
62  *      dsl_dir_rename_sync/w:
63  *      dsl_prop_changed_notify/r:
64  *
65  * os_obj_lock
66  *   must be held before:
67  *      everything except dp_config_rwlock
68  *   protects os_obj_next
69  *   held from:
70  *      dmu_object_alloc: dn_dbufs_mtx, db_mtx, hash_mutexes, dn_struct_rwlock
71  *
72  * dn_struct_rwlock
73  *   must be held before:
74  *      everything except dp_config_rwlock and os_obj_lock
75  *   protects structure of dnode (eg. nlevels)
76  *      db_blkptr can change when syncing out change to nlevels
77  *      dn_maxblkid
78  *      dn_nlevels
79  *      dn_*blksz*
80  *      phys nlevels, maxblkid, physical blkptr_t's (?)
81  *   held from:
82  *      callers of dbuf_read_impl, dbuf_hold[_impl], dbuf_prefetch
83  *      dmu_object_info_from_dnode: dn_dirty_mtx (dn_datablksz)
84  *      dmu_tx_count_free:
85  *      dbuf_read_impl: db_mtx, dmu_zfetch()
86  *      dmu_zfetch: zf_rwlock/r, zst_lock, dbuf_prefetch()
87  *      dbuf_new_size: db_mtx
88  *      dbuf_dirty: db_mtx
89  *      dbuf_findbp: (callers, phys? - the real need)
90  *      dbuf_create: dn_dbufs_mtx, hash_mutexes, db_mtx (phys?)
91  *      dbuf_prefetch: dn_dirty_mtx, hash_mutexes, db_mtx, dn_dbufs_mtx
92  *      dbuf_hold_impl: hash_mutexes, db_mtx, dn_dbufs_mtx, dbuf_findbp()
93  *      dnode_sync/w (increase_indirection): db_mtx (phys)
94  *      dnode_set_blksz/w: dn_dbufs_mtx (dn_*blksz*)
95  *      dnode_new_blkid/w: (dn_maxblkid)
96  *      dnode_free_range/w: dn_dirty_mtx (dn_maxblkid)
97  *      dnode_next_offset: (phys)
98  *
99  * dn_dbufs_mtx
100  *    must be held before:
101  *      db_mtx, hash_mutexes
102  *    protects:
103  *      dn_dbufs
104  *      dn_evicted
105  *    held from:
106  *      dmu_evict_user: db_mtx (dn_dbufs)
107  *      dbuf_free_range: db_mtx (dn_dbufs)
108  *      dbuf_remove_ref: db_mtx, callees:
109  *              dbuf_hash_remove: hash_mutexes, db_mtx
110  *      dbuf_create: hash_mutexes, db_mtx (dn_dbufs)
111  *      dnode_set_blksz: (dn_dbufs)
112  *
113  * hash_mutexes (global)
114  *   must be held before:
115  *      db_mtx
116  *   protects dbuf_hash_table (global) and db_hash_next
117  *   held from:
118  *      dbuf_find: db_mtx
119  *      dbuf_hash_insert: db_mtx
120  *      dbuf_hash_remove: db_mtx
121  *
122  * db_mtx (meta-leaf)
123  *   must be held before:
124  *      dn_mtx, dn_dirty_mtx, dd_lock (leaf mutexes)
125  *   protects:
126  *      db_state
127  *      db_holds
128  *      db_buf
129  *      db_changed
130  *      db_data_pending
131  *      db_dirtied
132  *      db_link
133  *      db_dirty_node (??)
134  *      db_dirtycnt
135  *      db_d.*
136  *      db.*
137  *   held from:
138  *      dbuf_dirty: dn_mtx, dn_dirty_mtx
139  *      dbuf_dirty->dsl_dir_willuse_space: dd_lock
140  *      dbuf_dirty->dbuf_new_block->dsl_dataset_block_freeable: dd_lock
141  *      dbuf_undirty: dn_dirty_mtx (db_d)
142  *      dbuf_write_done: dn_dirty_mtx (db_state)
143  *      dbuf_*
144  *      dmu_buf_update_user: none (db_d)
145  *      dmu_evict_user: none (db_d) (maybe can eliminate)
146  *      dbuf_find: none (db_holds)
147  *      dbuf_hash_insert: none (db_holds)
148  *      dmu_buf_read_array_impl: none (db_state, db_changed)
149  *      dmu_sync: none (db_dirty_node, db_d)
150  *      dnode_reallocate: none (db)
151  *
152  * dn_mtx (leaf)
153  *   protects:
154  *      dn_dirty_dbufs
155  *      dn_ranges
156  *      phys accounting
157  *      dn_allocated_txg
158  *      dn_free_txg
159  *      dn_assigned_txg
160  *      dd_assigned_tx
161  *      dn_notxholds
162  *      dn_dirtyctx
163  *      dn_dirtyctx_firstset
164  *      (dn_phys copy fields?)
165  *      (dn_phys contents?)
166  *   held from:
167  *      dnode_*
168  *      dbuf_dirty: none
169  *      dbuf_sync: none (phys accounting)
170  *      dbuf_undirty: none (dn_ranges, dn_dirty_dbufs)
171  *      dbuf_write_done: none (phys accounting)
172  *      dmu_object_info_from_dnode: none (accounting)
173  *      dmu_tx_commit: none
174  *      dmu_tx_hold_object_impl: none
175  *      dmu_tx_try_assign: dn_notxholds(cv)
176  *      dmu_tx_unassign: none
177  *
178  * dd_lock
179  *    must be held before:
180  *      ds_lock
181  *      ancestors' dd_lock
182  *    protects:
183  *      dd_prop_cbs
184  *      dd_sync_*
185  *      dd_used_bytes
186  *      dd_tempreserved
187  *      dd_space_towrite
188  *      dd_myname
189  *      dd_phys accounting?
190  *    held from:
191  *      dsl_dir_*
192  *      dsl_prop_changed_notify: none (dd_prop_cbs)
193  *      dsl_prop_register: none (dd_prop_cbs)
194  *      dsl_prop_unregister: none (dd_prop_cbs)
195  *      dsl_dataset_block_freeable: none (dd_sync_*)
196  *
197  * os_lock (leaf)
198  *   protects:
199  *      os_dirty_dnodes
200  *      os_free_dnodes
201  *      os_dnodes
202  *      os_downgraded_dbufs
203  *      dn_dirtyblksz
204  *      dn_dirty_link
205  *   held from:
206  *      dnode_create: none (os_dnodes)
207  *      dnode_destroy: none (os_dnodes)
208  *      dnode_setdirty: none (dn_dirtyblksz, os_*_dnodes)
209  *      dnode_free: none (dn_dirtyblksz, os_*_dnodes)
210  *
211  * ds_lock
212  *    protects:
213  *      ds_user_ptr
214  *      ds_user_evice_func
215  *      ds_open_refcount
216  *      ds_snapname
217  *      ds_phys accounting
218  *      ds_reserved
219  *    held from:
220  *      dsl_dataset_*
221  *
222  * dr_mtx (leaf)
223  *    protects:
224  *      dr_children
225  *    held from:
226  *      dbuf_dirty
227  *      dbuf_undirty
228  *      dbuf_sync_indirect
229  *      dnode_new_blkid
230  */
231
232 struct objset;
233 struct dmu_pool;
234
235 #ifdef  __cplusplus
236 }
237 #endif
238
239 #endif  /* _SYS_DMU_IMPL_H */