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mirror_zfs/include/sys/dmu_impl.h
John Poduska e6b28efccc
Prevent race condition in dnode_dest (#10101) 
dnode_special_close() waits for the refcount of dn_holds to go to zero
without holding the dn_mtx. dnode_rele_and_unlock() does the final
remove to dn_holds with dn_mtx being held:

	refs = zfs_refcount_remove(&dn->dn_holds, tag);
	mutex_exit(&dn->dn_mtx);

So, there is a race condition after the remove until dn_mtx is
dropped. During that time, dnode_destroy() can get called, which ends
up in dnode_dest() calling mutex_destroy() and a panic since the lock
is still held.

This change adds a condvar to wait for the final dnode_rele_and_unlock()
to release the dn_mtx before calling dnode_destroy().

Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: John Poduska <jpoduska@datto.com>
Closes #7814
Closes #10101
2020-03-12 10:25:56 -07:00

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/*
* 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 http://www.opensolaris.org/os/licensing.
* 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 2010 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* Copyright (c) 2012, Joyent, Inc. All rights reserved.
* Copyright (c) 2013, 2018 by Delphix. All rights reserved.
*/
#ifndef _SYS_DMU_IMPL_H
#define _SYS_DMU_IMPL_H
#include <sys/txg_impl.h>
#include <sys/zio.h>
#include <sys/dnode.h>
#include <sys/zfs_context.h>
#include <sys/zfs_ioctl.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* 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
*
* XXX 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)
* 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
* dn_dirty_txg
* dd_assigned_tx
* dn_notxholds
* dn_nodnholds
* 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)
*
* 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
*/
struct objset;
struct dmu_pool;
typedef struct dmu_xuio {
int next;
int cnt;
struct arc_buf **bufs;
iovec_t *iovp;
} dmu_xuio_t;
typedef struct dmu_sendstatus {
list_node_t dss_link;
int dss_outfd;
proc_t *dss_proc;
offset_t *dss_off;
uint64_t dss_blocks; /* blocks visited during the sending process */
} dmu_sendstatus_t;
void dmu_object_zapify(objset_t *, uint64_t, dmu_object_type_t, dmu_tx_t *);
void dmu_object_free_zapified(objset_t *, uint64_t, dmu_tx_t *);
int dmu_buf_hold_noread(objset_t *, uint64_t, uint64_t,
void *, dmu_buf_t **);
#ifdef __cplusplus
}
#endif
#endif /* _SYS_DMU_IMPL_H */
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