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author | mav <mav@FreeBSD.org> | 2015-10-03 07:29:56 +0000 |
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committer | mav <mav@FreeBSD.org> | 2015-10-03 07:29:56 +0000 |
commit | 4a52577541ebbe34a9fa8abe3948a8514c63258c (patch) | |
tree | 8ed8ab1f80ef30fc8881b08dd4e4e6ea57f4f7c3 /sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c | |
parent | 3529a708dddb3cca632de7b55ab67db8aa2f543d (diff) | |
download | FreeBSD-src-4a52577541ebbe34a9fa8abe3948a8514c63258c.zip FreeBSD-src-4a52577541ebbe34a9fa8abe3948a8514c63258c.tar.gz |
MFC r286575: 5056 ZFS deadlock on db_mtx and dn_holds
Reviewed by: Will Andrews <willa@spectralogic.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Justin Gibbs <justing@spectralogic.com>
illumos/illumos-gate@bc9014e6a81272073b9854d9f65dd59e18d18c35
Diffstat (limited to 'sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c')
-rw-r--r-- | sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c | 81 |
1 files changed, 52 insertions, 29 deletions
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c index 8848677..4af50f5 100644 --- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c @@ -21,6 +21,7 @@ /* * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2012, 2015 by Delphix. All rights reserved. + * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved. */ #include <sys/zfs_context.h> @@ -405,8 +406,9 @@ static dnode_t * dnode_create(objset_t *os, dnode_phys_t *dnp, dmu_buf_impl_t *db, uint64_t object, dnode_handle_t *dnh) { - dnode_t *dn = kmem_cache_alloc(dnode_cache, KM_SLEEP); + dnode_t *dn; + dn = kmem_cache_alloc(dnode_cache, KM_SLEEP); ASSERT(!POINTER_IS_VALID(dn->dn_objset)); dn->dn_moved = 0; @@ -443,13 +445,31 @@ dnode_create(objset_t *os, dnode_phys_t *dnp, dmu_buf_impl_t *db, ASSERT(DMU_OT_IS_VALID(dn->dn_phys->dn_type)); mutex_enter(&os->os_lock); - list_insert_head(&os->os_dnodes, dn); + if (dnh->dnh_dnode != NULL) { + /* Lost the allocation race. */ + mutex_exit(&os->os_lock); + kmem_cache_free(dnode_cache, dn); + return (dnh->dnh_dnode); + } + + /* + * Exclude special dnodes from os_dnodes so an empty os_dnodes + * signifies that the special dnodes have no references from + * their children (the entries in os_dnodes). This allows + * dnode_destroy() to easily determine if the last child has + * been removed and then complete eviction of the objset. + */ + if (!DMU_OBJECT_IS_SPECIAL(object)) + list_insert_head(&os->os_dnodes, dn); membar_producer(); + /* - * Everything else must be valid before assigning dn_objset makes the - * dnode eligible for dnode_move(). + * Everything else must be valid before assigning dn_objset + * makes the dnode eligible for dnode_move(). */ dn->dn_objset = os; + + dnh->dnh_dnode = dn; mutex_exit(&os->os_lock); arc_space_consume(sizeof (dnode_t), ARC_SPACE_OTHER); @@ -463,12 +483,18 @@ static void dnode_destroy(dnode_t *dn) { objset_t *os = dn->dn_objset; + boolean_t complete_os_eviction = B_FALSE; ASSERT((dn->dn_id_flags & DN_ID_NEW_EXIST) == 0); mutex_enter(&os->os_lock); POINTER_INVALIDATE(&dn->dn_objset); - list_remove(&os->os_dnodes, dn); + if (!DMU_OBJECT_IS_SPECIAL(dn->dn_object)) { + list_remove(&os->os_dnodes, dn); + complete_os_eviction = + list_is_empty(&os->os_dnodes) && + list_link_active(&os->os_evicting_node); + } mutex_exit(&os->os_lock); /* the dnode can no longer move, so we can release the handle */ @@ -503,6 +529,9 @@ dnode_destroy(dnode_t *dn) dmu_zfetch_rele(&dn->dn_zfetch); kmem_cache_free(dnode_cache, dn); arc_space_return(sizeof (dnode_t), ARC_SPACE_OTHER); + + if (complete_os_eviction) + dmu_objset_evict_done(os); } void @@ -971,33 +1000,32 @@ dnode_special_close(dnode_handle_t *dnh) */ while (refcount_count(&dn->dn_holds) > 0) delay(1); + ASSERT(dn->dn_dbuf == NULL || + dmu_buf_get_user(&dn->dn_dbuf->db) == NULL); zrl_add(&dnh->dnh_zrlock); dnode_destroy(dn); /* implicit zrl_remove() */ zrl_destroy(&dnh->dnh_zrlock); dnh->dnh_dnode = NULL; } -dnode_t * +void dnode_special_open(objset_t *os, dnode_phys_t *dnp, uint64_t object, dnode_handle_t *dnh) { - dnode_t *dn = dnode_create(os, dnp, NULL, object, dnh); - dnh->dnh_dnode = dn; + dnode_t *dn; + + dn = dnode_create(os, dnp, NULL, object, dnh); zrl_init(&dnh->dnh_zrlock); DNODE_VERIFY(dn); - return (dn); } static void -dnode_buf_pageout(dmu_buf_t *db, void *arg) +dnode_buf_pageout(void *dbu) { - dnode_children_t *children_dnodes = arg; + dnode_children_t *children_dnodes = dbu; int i; - int epb = db->db_size >> DNODE_SHIFT; - ASSERT(epb == children_dnodes->dnc_count); - - for (i = 0; i < epb; i++) { + for (i = 0; i < children_dnodes->dnc_count; i++) { dnode_handle_t *dnh = &children_dnodes->dnc_children[i]; dnode_t *dn; @@ -1027,7 +1055,7 @@ dnode_buf_pageout(dmu_buf_t *db, void *arg) dnh->dnh_dnode = NULL; } kmem_free(children_dnodes, sizeof (dnode_children_t) + - epb * sizeof (dnode_handle_t)); + children_dnodes->dnc_count * sizeof (dnode_handle_t)); } /* @@ -1117,10 +1145,11 @@ dnode_hold_impl(objset_t *os, uint64_t object, int flag, dnh = &children_dnodes->dnc_children[0]; for (i = 0; i < epb; i++) { zrl_init(&dnh[i].dnh_zrlock); - dnh[i].dnh_dnode = NULL; } - if (winner = dmu_buf_set_user(&db->db, children_dnodes, - dnode_buf_pageout)) { + dmu_buf_init_user(&children_dnodes->dnc_dbu, + dnode_buf_pageout, NULL); + winner = dmu_buf_set_user(&db->db, &children_dnodes->dnc_dbu); + if (winner != NULL) { for (i = 0; i < epb; i++) { zrl_destroy(&dnh[i].dnh_zrlock); @@ -1135,17 +1164,11 @@ dnode_hold_impl(objset_t *os, uint64_t object, int flag, dnh = &children_dnodes->dnc_children[idx]; zrl_add(&dnh->dnh_zrlock); - if ((dn = dnh->dnh_dnode) == NULL) { + dn = dnh->dnh_dnode; + if (dn == NULL) { dnode_phys_t *phys = (dnode_phys_t *)db->db.db_data+idx; - dnode_t *winner; dn = dnode_create(os, phys, db, object, dnh); - winner = atomic_cas_ptr(&dnh->dnh_dnode, NULL, dn); - if (winner != NULL) { - zrl_add(&dnh->dnh_zrlock); - dnode_destroy(dn); /* implicit zrl_remove() */ - dn = winner; - } } mutex_enter(&dn->dn_mtx); @@ -1159,10 +1182,10 @@ dnode_hold_impl(objset_t *os, uint64_t object, int flag, dbuf_rele(db, FTAG); return (type == DMU_OT_NONE ? ENOENT : EEXIST); } - mutex_exit(&dn->dn_mtx); - if (refcount_add(&dn->dn_holds, tag) == 1) dbuf_add_ref(db, dnh); + mutex_exit(&dn->dn_mtx); + /* Now we can rely on the hold to prevent the dnode from moving. */ zrl_remove(&dnh->dnh_zrlock); |