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      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 2007 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 #pragma ident	"@(#)dmu_impl.h	1.2	07/02/02 SMI"
     30 
     31 #include <sys/txg_impl.h>
     32 #include <sys/zio.h>
     33 #include <sys/dnode.h>
     34 #include <sys/zfs_context.h>
     35 
     36 #ifdef	__cplusplus
     37 extern "C" {
     38 #endif
     39 
     40 /*
     41  * This is the locking strategy for the DMU.  Numbers in parenthesis are
     42  * cases that use that lock order, referenced below:
     43  *
     44  * ARC is self-contained
     45  * bplist is self-contained
     46  * refcount is self-contained
     47  * txg is self-contained (hopefully!)
     48  * zst_lock
     49  * zf_rwlock
     50  *
     51  * XXX try to improve evicting path?
     52  *
     53  * dp_config_rwlock > os_obj_lock > dn_struct_rwlock >
     54  * 	dn_dbufs_mtx > hash_mutexes > db_mtx > leafs
     55  *
     56  * dp_config_rwlock
     57  *    must be held before: everything
     58  *    protects dd namespace changes
     59  *    protects property changes globally
     60  *    held from:
     61  *    	dsl_dir_open/r:
     62  *    	dsl_dir_create_sync/w:
     63  *    	dsl_dir_sync_destroy/w:
     64  *    	dsl_dir_rename_sync/w:
     65  *    	dsl_prop_changed_notify/r:
     66  *
     67  * os_obj_lock
     68  *   must be held before:
     69  *   	everything except dp_config_rwlock
     70  *   protects os_obj_next
     71  *   held from:
     72  *   	dmu_object_alloc: dn_dbufs_mtx, db_mtx, hash_mutexes, dn_struct_rwlock
     73  *
     74  * dn_struct_rwlock
     75  *   must be held before:
     76  *   	everything except dp_config_rwlock and os_obj_lock
     77  *   protects structure of dnode (eg. nlevels)
     78  *   	db_blkptr can change when syncing out change to nlevels
     79  *   	dn_maxblkid
     80  *   	dn_nlevels
     81  *   	dn_*blksz*
     82  *   	phys nlevels, maxblkid, physical blkptr_t's (?)
     83  *   held from:
     84  *   	callers of dbuf_read_impl, dbuf_hold[_impl], dbuf_prefetch
     85  *   	dmu_object_info_from_dnode: dn_dirty_mtx (dn_datablksz)
     86  *   	dmu_tx_count_free:
     87  *   	dbuf_read_impl: db_mtx, dmu_zfetch()
     88  *   	dmu_zfetch: zf_rwlock/r, zst_lock, dbuf_prefetch()
     89  *   	dbuf_new_size: db_mtx
     90  *   	dbuf_dirty: db_mtx
     91  *	dbuf_findbp: (callers, phys? - the real need)
     92  *	dbuf_create: dn_dbufs_mtx, hash_mutexes, db_mtx (phys?)
     93  *	dbuf_prefetch: dn_dirty_mtx, hash_mutexes, db_mtx, dn_dbufs_mtx
     94  *	dbuf_hold_impl: hash_mutexes, db_mtx, dn_dbufs_mtx, dbuf_findbp()
     95  *	dnode_sync/w (increase_indirection): db_mtx (phys)
     96  *	dnode_set_blksz/w: dn_dbufs_mtx (dn_*blksz*)
     97  *	dnode_new_blkid/w: (dn_maxblkid)
     98  *	dnode_free_range/w: dn_dirty_mtx (dn_maxblkid)
     99  *	dnode_next_offset: (phys)
    100  *
    101  * dn_dbufs_mtx
    102  *    must be held before:
    103  *    	db_mtx, hash_mutexes
    104  *    protects:
    105  *    	dn_dbufs
    106  *    	dn_evicted
    107  *    held from:
    108  *    	dmu_evict_user: db_mtx (dn_dbufs)
    109  *    	dbuf_free_range: db_mtx (dn_dbufs)
    110  *    	dbuf_remove_ref: db_mtx, callees:
    111  *    		dbuf_hash_remove: hash_mutexes, db_mtx
    112  *    	dbuf_create: hash_mutexes, db_mtx (dn_dbufs)
    113  *    	dnode_set_blksz: (dn_dbufs)
    114  *
    115  * hash_mutexes (global)
    116  *   must be held before:
    117  *   	db_mtx
    118  *   protects dbuf_hash_table (global) and db_hash_next
    119  *   held from:
    120  *   	dbuf_find: db_mtx
    121  *   	dbuf_hash_insert: db_mtx
    122  *   	dbuf_hash_remove: db_mtx
    123  *
    124  * db_mtx (meta-leaf)
    125  *   must be held before:
    126  *   	dn_mtx, dn_dirty_mtx, dd_lock (leaf mutexes)
    127  *   protects:
    128  *   	db_state
    129  * 	db_holds
    130  * 	db_buf
    131  * 	db_changed
    132  * 	db_data_pending
    133  * 	db_dirtied
    134  * 	db_link
    135  * 	db_dirty_node (??)
    136  * 	db_dirtycnt
    137  * 	db_d.*
    138  * 	db.*
    139  *   held from:
    140  * 	dbuf_dirty: dn_mtx, dn_dirty_mtx
    141  * 	dbuf_dirty->dsl_dir_willuse_space: dd_lock
    142  * 	dbuf_dirty->dbuf_new_block->dsl_dataset_block_freeable: dd_lock
    143  * 	dbuf_undirty: dn_dirty_mtx (db_d)
    144  * 	dbuf_write_done: dn_dirty_mtx (db_state)
    145  * 	dbuf_*
    146  * 	dmu_buf_update_user: none (db_d)
    147  * 	dmu_evict_user: none (db_d) (maybe can eliminate)
    148  *   	dbuf_find: none (db_holds)
    149  *   	dbuf_hash_insert: none (db_holds)
    150  *   	dmu_buf_read_array_impl: none (db_state, db_changed)
    151  *   	dmu_sync: none (db_dirty_node, db_d)
    152  *   	dnode_reallocate: none (db)
    153  *
    154  * dn_mtx (leaf)
    155  *   protects:
    156  *   	dn_dirty_dbufs
    157  *   	dn_ranges
    158  *   	phys accounting
    159  * 	dn_allocated_txg
    160  * 	dn_free_txg
    161  * 	dn_assigned_txg
    162  * 	dd_assigned_tx
    163  * 	dn_notxholds
    164  * 	dn_dirtyctx
    165  * 	dn_dirtyctx_firstset
    166  * 	(dn_phys copy fields?)
    167  * 	(dn_phys contents?)
    168  *   held from:
    169  *   	dnode_*
    170  *   	dbuf_dirty: none
    171  *   	dbuf_sync: none (phys accounting)
    172  *   	dbuf_undirty: none (dn_ranges, dn_dirty_dbufs)
    173  *   	dbuf_write_done: none (phys accounting)
    174  *   	dmu_object_info_from_dnode: none (accounting)
    175  *   	dmu_tx_commit: none
    176  *   	dmu_tx_hold_object_impl: none
    177  *   	dmu_tx_try_assign: dn_notxholds(cv)
    178  *   	dmu_tx_unassign: none
    179  *
    180  * dd_lock (leaf)
    181  *    protects:
    182  *    	dd_prop_cbs
    183  *    	dd_sync_*
    184  *    	dd_used_bytes
    185  *    	dd_tempreserved
    186  *    	dd_space_towrite
    187  *    	dd_myname
    188  *    	dd_phys accounting?
    189  *    held from:
    190  *    	dsl_dir_*
    191  *    	dsl_prop_changed_notify: none (dd_prop_cbs)
    192  *    	dsl_prop_register: none (dd_prop_cbs)
    193  *    	dsl_prop_unregister: none (dd_prop_cbs)
    194  *    	dsl_dataset_block_freeable: none (dd_sync_*)
    195  *
    196  * os_lock (leaf)
    197  *   protects:
    198  *   	os_dirty_dnodes
    199  *   	os_free_dnodes
    200  *   	os_dnodes
    201  *   	os_downgraded_dbufs
    202  *   	dn_dirtyblksz
    203  *   	dn_dirty_link
    204  *   held from:
    205  *   	dnode_create: none (os_dnodes)
    206  *   	dnode_destroy: none (os_dnodes)
    207  *   	dnode_setdirty: none (dn_dirtyblksz, os_*_dnodes)
    208  *   	dnode_free: none (dn_dirtyblksz, os_*_dnodes)
    209  *
    210  * ds_lock (leaf)
    211  *    protects:
    212  *    	ds_user_ptr
    213  *    	ds_user_evice_func
    214  *    	ds_open_refcount
    215  *    	ds_snapname
    216  *    	ds_phys accounting
    217  *    held from:
    218  *    	dsl_dataset_*
    219  *
    220  * dr_mtx (leaf)
    221  *    protects:
    222  *	dr_children
    223  *    held from:
    224  *	dbuf_dirty
    225  *	dbuf_undirty
    226  *	dbuf_sync_indirect
    227  *	dnode_new_blkid
    228  */
    229 
    230 struct objset;
    231 struct dmu_pool;
    232 
    233 #ifdef	__cplusplus
    234 }
    235 #endif
    236 
    237 #endif	/* _SYS_DMU_IMPL_H */
    238