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Illumos 5056 - ZFS deadlock on db_mtx and dn_holds

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5056 ZFS deadlock on db_mtx and dn_holds
Author: Justin Gibbs <justing@spectralogic.com>
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>

References:
  https://www.illumos.org/issues/5056
  https://github.com/illumos/illumos-gate/commit/bc9014e

Porting Notes:

sa_handle_get_from_db():
  - the original patch includes an otherwise unmentioned fix for a
    possible usage of an uninitialised variable

dmu_objset_open_impl():
  - Under Illumos list_link_init() is the same as filling a list_node_t
    with NULLs, so they don't notice if they miss doing list_link_init()
    on a zero'd containing structure (e.g. allocated with kmem_zalloc as
    here). Under Linux, not so much: an uninitialised list_node_t goes
    "Boom!" some time later when it's used or destroyed.

dmu_objset_evict_dbufs():
  - reduce stack usage using kmem_alloc()

Ported-by: Chris Dunlop <chris@onthe.net.au>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
This commit is contained in:
Justin T. Gibbs
2015-04-02 14:44:32 +11:00
committed by Brian Behlendorf
parent d683ddbb72
commit 0c66c32d1d
35 changed files with 645 additions and 316 deletions
Download Patch File Download Diff File Expand all files Collapse all files
module/zfs/dmu_objset.c
+74 -43
View File
@@ -23,6 +23,7 @@
* Copyright (c) 2012, 2014 by Delphix. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2013, Joyent, Inc. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/
/* Portions Copyright 2010 Robert Milkowski */
@@ -347,7 +348,7 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
zfs_prop_to_name(ZFS_PROP_SECONDARYCACHE),
secondary_cache_changed_cb, os);
}
if (!dsl_dataset_is_snapshot(ds)) {
if (!ds->ds_is_snapshot) {
if (err == 0) {
err = dsl_prop_register(ds,
zfs_prop_to_name(ZFS_PROP_CHECKSUM),
@@ -404,7 +405,7 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
os->os_secondary_cache = ZFS_CACHE_ALL;
}
if (ds == NULL || !dsl_dataset_is_snapshot(ds))
if (ds == NULL || !ds->ds_is_snapshot)
os->os_zil_header = os->os_phys->os_zil_header;
os->os_zil = zil_alloc(os, &os->os_zil_header);
@@ -419,20 +420,19 @@ dmu_objset_open_impl(spa_t *spa, dsl_dataset_t *ds, blkptr_t *bp,
list_create(&os->os_downgraded_dbufs, sizeof (dmu_buf_impl_t),
offsetof(dmu_buf_impl_t, db_link));
list_link_init(&os->os_evicting_node);
mutex_init(&os->os_lock, NULL, MUTEX_DEFAULT, NULL);
mutex_init(&os->os_obj_lock, NULL, MUTEX_DEFAULT, NULL);
mutex_init(&os->os_user_ptr_lock, NULL, MUTEX_DEFAULT, NULL);
DMU_META_DNODE(os) = dnode_special_open(os,
&os->os_phys->os_meta_dnode, DMU_META_DNODE_OBJECT,
&os->os_meta_dnode);
dnode_special_open(os, &os->os_phys->os_meta_dnode,
DMU_META_DNODE_OBJECT, &os->os_meta_dnode);
if (arc_buf_size(os->os_phys_buf) >= sizeof (objset_phys_t)) {
DMU_USERUSED_DNODE(os) = dnode_special_open(os,
&os->os_phys->os_userused_dnode, DMU_USERUSED_OBJECT,
&os->os_userused_dnode);
DMU_GROUPUSED_DNODE(os) = dnode_special_open(os,
&os->os_phys->os_groupused_dnode, DMU_GROUPUSED_OBJECT,
&os->os_groupused_dnode);
dnode_special_open(os, &os->os_phys->os_userused_dnode,
DMU_USERUSED_OBJECT, &os->os_userused_dnode);
dnode_special_open(os, &os->os_phys->os_groupused_dnode,
DMU_GROUPUSED_OBJECT, &os->os_groupused_dnode);
}
*osp = os;
@@ -520,7 +520,7 @@ dmu_objset_own(const char *name, dmu_objset_type_t type,
} else if (type != DMU_OST_ANY && type != (*osp)->os_phys->os_type) {
dsl_dataset_disown(ds, tag);
return (SET_ERROR(EINVAL));
} else if (!readonly && dsl_dataset_is_snapshot(ds)) {
} else if (!readonly && ds->ds_is_snapshot) {
dsl_dataset_disown(ds, tag);
return (SET_ERROR(EROFS));
}
@@ -576,41 +576,57 @@ dmu_objset_disown(objset_t *os, void *tag)
void
dmu_objset_evict_dbufs(objset_t *os)
{
dnode_t *dn_marker;
dnode_t *dn;
dn_marker = kmem_alloc(sizeof (dnode_t), KM_SLEEP);
mutex_enter(&os->os_lock);
dn = list_head(&os->os_dnodes);
while (dn != NULL) {
/*
* Skip dnodes without holds. We have to do this dance
* because dnode_add_ref() only works if there is already a
* hold. If the dnode has no holds, then it has no dbufs.
*/
if (dnode_add_ref(dn, FTAG)) {
list_insert_after(&os->os_dnodes, dn, dn_marker);
mutex_exit(&os->os_lock);
/* process the mdn last, since the other dnodes have holds on it */
list_remove(&os->os_dnodes, DMU_META_DNODE(os));
list_insert_tail(&os->os_dnodes, DMU_META_DNODE(os));
dnode_evict_dbufs(dn);
dnode_rele(dn, FTAG);
/*
* Find the first dnode with holds. We have to do this dance
* because dnode_add_ref() only works if you already have a
* hold. If there are no holds then it has no dbufs so OK to
* skip.
*/
for (dn = list_head(&os->os_dnodes);
dn && !dnode_add_ref(dn, FTAG);
dn = list_next(&os->os_dnodes, dn))
continue;
while (dn) {
dnode_t *next_dn = dn;
do {
next_dn = list_next(&os->os_dnodes, next_dn);
} while (next_dn && !dnode_add_ref(next_dn, FTAG));
mutex_exit(&os->os_lock);
dnode_evict_dbufs(dn);
dnode_rele(dn, FTAG);
mutex_enter(&os->os_lock);
dn = next_dn;
mutex_enter(&os->os_lock);
dn = list_next(&os->os_dnodes, dn_marker);
list_remove(&os->os_dnodes, dn_marker);
} else {
dn = list_next(&os->os_dnodes, dn);
}
}
mutex_exit(&os->os_lock);
kmem_free(dn_marker, sizeof (dnode_t));
if (DMU_USERUSED_DNODE(os) != NULL) {
dnode_evict_dbufs(DMU_GROUPUSED_DNODE(os));
dnode_evict_dbufs(DMU_USERUSED_DNODE(os));
}
dnode_evict_dbufs(DMU_META_DNODE(os));
}
/*
* Objset eviction processing is split into into two pieces.
* The first marks the objset as evicting, evicts any dbufs that
* have a refcount of zero, and then queues up the objset for the
* second phase of eviction. Once os->os_dnodes has been cleared by
* dnode_buf_pageout()->dnode_destroy(), the second phase is executed.
* The second phase closes the special dnodes, dequeues the objset from
* the list of those undergoing eviction, and finally frees the objset.
*
* NOTE: Due to asynchronous eviction processing (invocation of
* dnode_buf_pageout()), it is possible for the meta dnode for the
* objset to have no holds even though os->os_dnodes is not empty.
*/
void
dmu_objset_evict(objset_t *os)
{
@@ -622,7 +638,7 @@ dmu_objset_evict(objset_t *os)
ASSERT(!dmu_objset_is_dirty(os, t));
if (ds) {
if (!dsl_dataset_is_snapshot(ds)) {
if (!ds->ds_is_snapshot) {
VERIFY0(dsl_prop_unregister(ds,
zfs_prop_to_name(ZFS_PROP_CHECKSUM),
checksum_changed_cb, os));
@@ -656,8 +672,24 @@ dmu_objset_evict(objset_t *os)
if (os->os_sa)
sa_tear_down(os);
os->os_evicting = B_TRUE;
dmu_objset_evict_dbufs(os);
mutex_enter(&os->os_lock);
spa_evicting_os_register(os->os_spa, os);
if (list_is_empty(&os->os_dnodes)) {
mutex_exit(&os->os_lock);
dmu_objset_evict_done(os);
} else {
mutex_exit(&os->os_lock);
}
}
void
dmu_objset_evict_done(objset_t *os)
{
ASSERT3P(list_head(&os->os_dnodes), ==, NULL);
dnode_special_close(&os->os_meta_dnode);
if (DMU_USERUSED_DNODE(os)) {
dnode_special_close(&os->os_userused_dnode);
@@ -665,8 +697,6 @@ dmu_objset_evict(objset_t *os)
}
zil_free(os->os_zil);
ASSERT3P(list_head(&os->os_dnodes), ==, NULL);
VERIFY(arc_buf_remove_ref(os->os_phys_buf, &os->os_phys_buf));
/*
@@ -681,6 +711,7 @@ dmu_objset_evict(objset_t *os)
mutex_destroy(&os->os_lock);
mutex_destroy(&os->os_obj_lock);
mutex_destroy(&os->os_user_ptr_lock);
spa_evicting_os_deregister(os->os_spa, os);
kmem_free(os, sizeof (objset_t));
}
@@ -888,7 +919,7 @@ dmu_objset_clone_check(void *arg, dmu_tx_t *tx)
}
/* You can only clone snapshots, not the head datasets. */
if (!dsl_dataset_is_snapshot(origin)) {
if (!origin->ds_is_snapshot) {
dsl_dataset_rele(origin, FTAG);
return (SET_ERROR(EINVAL));
}
@@ -1453,7 +1484,7 @@ int
dmu_objset_is_snapshot(objset_t *os)
{
if (os->os_dsl_dataset != NULL)
return (dsl_dataset_is_snapshot(os->os_dsl_dataset));
return (os->os_dsl_dataset->ds_is_snapshot);
else
return (B_FALSE);
}