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MFV r353558: 10572 10579 Fix race in dnode_check_slots_free()

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illumos/illumos-gate@aa02ea0194
aa02ea0194

10572 Fix race in dnode_check_slots_free()
https://www.illumos.org/issues/10572
  The Fix from ZoL:
  Currently, dnode_check_slots_free() works by checking dn->dn_type
  in the dnode to determine if the dnode is reclaimable. However,
  there is a small window of time between dnode_free_sync() in the
  first call to dsl_dataset_sync() and when the useraccounting code
  is run when the type is set DMU_OT_NONE, but the dnode is not yet
  evictable, leading to crashes. This patch adds the ability for
  dnodes to track which txg they were last dirtied in and adds a
  check for this before performing the reclaim.

  This patch also corrects several instances when dn_dirty_link was
  treated as a list_node_t when it is technically a multilist_node_t.

10579 Don't allow dnode allocation if dn_holds != 0
https://www.illumos.org/issues/10579
  The fix from ZoL:
  This patch simply fixes a small bug where dnode_hold_impl() could
  attempt to allocate a dnode that was in the process of being freed,
  but which still had active references. This patch simply adds the
  required check.

Author: Tom Caputi <tcaputi@datto.com>
Reported by:	delphij
MFC after:	2 weeks
X-MFC with:	r353176
This commit is contained in:
Andriy Gapon 2019-10-15 14:29:18 +00:00
commit 563db1a947
5 changed files with 43 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dbuf.c
View File

@ -1812,6 +1812,9 @@ dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
FTAG);
}
}
if (tx->tx_txg > dn->dn_dirty_txg)
dn->dn_dirty_txg = tx->tx_txg;
mutex_exit(&dn->dn_mtx);
if (db->db_blkid == DMU_SPILL_BLKID)

15
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dmu_objset.c
View File

@ -1249,10 +1249,23 @@ dmu_objset_sync_dnodes(multilist_sublist_t *list, dmu_tx_t *tx)
ASSERT3U(dn->dn_nlevels, <=, DN_MAX_LEVELS);
multilist_sublist_remove(list, dn);
/*
* If we are not doing useraccounting (os_synced_dnodes == NULL)
* we are done with this dnode for this txg. Unset dn_dirty_txg
* if later txgs aren't dirtying it so that future holders do
* not get a stale value. Otherwise, we will do this in
* userquota_updates_task() when processing has completely
* finished for this txg.
*/
multilist_t *newlist = dn->dn_objset->os_synced_dnodes;
if (newlist != NULL) {
(void) dnode_add_ref(dn, newlist);
multilist_insert(newlist, dn);
} else {
mutex_enter(&dn->dn_mtx);
if (dn->dn_dirty_txg == tx->tx_txg)
dn->dn_dirty_txg = 0;
mutex_exit(&dn->dn_mtx);
}
dnode_sync(dn, tx);
@ -1617,6 +1630,8 @@ userquota_updates_task(void *arg)
dn->dn_id_flags |= DN_ID_CHKED_BONUS;
}
dn->dn_id_flags &= ~(DN_ID_NEW_EXIST);
if (dn->dn_dirty_txg == spa_syncing_txg(os->os_spa))
dn->dn_dirty_txg = 0;
mutex_exit(&dn->dn_mtx);
multilist_sublist_remove(list, dn);

30
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/dnode.c
View File

@ -146,7 +146,7 @@ dnode_cons(void *arg, void *unused, int kmflag)
bzero(&dn->dn_next_blksz[0], sizeof (dn->dn_next_blksz));
for (i = 0; i < TXG_SIZE; i++) {
list_link_init(&dn->dn_dirty_link[i]);
multilist_link_init(&dn->dn_dirty_link[i]);
dn->dn_free_ranges[i] = NULL;
list_create(&dn->dn_dirty_records[i],
sizeof (dbuf_dirty_record_t),
@ -156,6 +156,7 @@ dnode_cons(void *arg, void *unused, int kmflag)
dn->dn_allocated_txg = 0;
dn->dn_free_txg = 0;
dn->dn_assigned_txg = 0;
dn->dn_dirty_txg = 0;
dn->dn_dirtyctx = 0;
dn->dn_dirtyctx_firstset = NULL;
dn->dn_bonus = NULL;
@ -194,7 +195,7 @@ dnode_dest(void *arg, void *unused)
ASSERT(!list_link_active(&dn->dn_link));
for (i = 0; i < TXG_SIZE; i++) {
ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
ASSERT(!multilist_link_active(&dn->dn_dirty_link[i]));
ASSERT3P(dn->dn_free_ranges[i], ==, NULL);
list_destroy(&dn->dn_dirty_records[i]);
ASSERT0(dn->dn_next_nblkptr[i]);
@ -209,6 +210,7 @@ dnode_dest(void *arg, void *unused)
ASSERT0(dn->dn_allocated_txg);
ASSERT0(dn->dn_free_txg);
ASSERT0(dn->dn_assigned_txg);
ASSERT0(dn->dn_dirty_txg);
ASSERT0(dn->dn_dirtyctx);
ASSERT3P(dn->dn_dirtyctx_firstset, ==, NULL);
ASSERT3P(dn->dn_bonus, ==, NULL);
@ -540,6 +542,7 @@ dnode_destroy(dnode_t *dn)
dn->dn_allocated_txg = 0;
dn->dn_free_txg = 0;
dn->dn_assigned_txg = 0;
dn->dn_dirty_txg = 0;
dn->dn_dirtyctx = 0;
if (dn->dn_dirtyctx_firstset != NULL) {
@ -609,6 +612,7 @@ dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
ASSERT(dn->dn_type == DMU_OT_NONE);
ASSERT0(dn->dn_maxblkid);
ASSERT0(dn->dn_allocated_txg);
ASSERT0(dn->dn_dirty_txg);
ASSERT0(dn->dn_assigned_txg);
ASSERT(refcount_is_zero(&dn->dn_tx_holds));
ASSERT3U(refcount_count(&dn->dn_holds), <=, 1);
@ -622,7 +626,7 @@ dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
ASSERT0(dn->dn_next_bonustype[i]);
ASSERT0(dn->dn_rm_spillblk[i]);
ASSERT0(dn->dn_next_blksz[i]);
ASSERT(!list_link_active(&dn->dn_dirty_link[i]));
ASSERT(!multilist_link_active(&dn->dn_dirty_link[i]));
ASSERT3P(list_head(&dn->dn_dirty_records[i]), ==, NULL);
ASSERT3P(dn->dn_free_ranges[i], ==, NULL);
}
@ -799,6 +803,7 @@ dnode_move_impl(dnode_t *odn, dnode_t *ndn)
ndn->dn_allocated_txg = odn->dn_allocated_txg;
ndn->dn_free_txg = odn->dn_free_txg;
ndn->dn_assigned_txg = odn->dn_assigned_txg;
ndn->dn_dirty_txg = odn->dn_dirty_txg;
ndn->dn_dirtyctx = odn->dn_dirtyctx;
ndn->dn_dirtyctx_firstset = odn->dn_dirtyctx_firstset;
ASSERT(refcount_count(&odn->dn_tx_holds) == 0);
@ -865,6 +870,7 @@ dnode_move_impl(dnode_t *odn, dnode_t *ndn)
odn->dn_allocated_txg = 0;
odn->dn_free_txg = 0;
odn->dn_assigned_txg = 0;
odn->dn_dirty_txg = 0;
odn->dn_dirtyctx = 0;
odn->dn_dirtyctx_firstset = NULL;
odn->dn_have_spill = B_FALSE;
@ -1091,6 +1097,10 @@ dnode_check_slots_free(dnode_children_t *children, int idx, int slots)
{
ASSERT3S(idx + slots, <=, DNODES_PER_BLOCK);
/*
* If all dnode slots are either already free or
* evictable return B_TRUE.
*/
for (int i = idx; i < idx + slots; i++) {
dnode_handle_t *dnh = &children->dnc_children[i];
dnode_t *dn = dnh->dnh_dnode;
@ -1099,18 +1109,18 @@ dnode_check_slots_free(dnode_children_t *children, int idx, int slots)
continue;
} else if (DN_SLOT_IS_PTR(dn)) {
mutex_enter(&dn->dn_mtx);
dmu_object_type_t type = dn->dn_type;
boolean_t can_free = (dn->dn_type == DMU_OT_NONE &&
refcount_is_zero(&dn->dn_holds) &&
!DNODE_IS_DIRTY(dn));
mutex_exit(&dn->dn_mtx);
if (type != DMU_OT_NONE)
if (!can_free)
return (B_FALSE);
continue;
else
continue;
} else {
return (B_FALSE);
}
return (B_FALSE);
}
return (B_TRUE);
@ -1634,7 +1644,7 @@ dnode_setdirty(dnode_t *dn, dmu_tx_t *tx)
/*
* If we are already marked dirty, we're done.
*/
if (list_link_active(&dn->dn_dirty_link[txg & TXG_MASK])) {
if (multilist_link_active(&dn->dn_dirty_link[txg & TXG_MASK])) {
multilist_sublist_unlock(mls);
return;
}

2
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dmu_impl.h
View File

@ -163,7 +163,7 @@ extern "C" {
* dn_allocated_txg
* dn_free_txg
* dn_assigned_txg
* dd_assigned_tx
* dn_dirty_txg
* dn_notxholds
* dn_dirtyctx
* dn_dirtyctx_firstset

4
sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/dnode.h
View File

@ -303,6 +303,7 @@ struct dnode {
uint64_t dn_allocated_txg;
uint64_t dn_free_txg;
uint64_t dn_assigned_txg;
uint64_t dn_dirty_txg; /* txg dnode was last dirtied */
kcondvar_t dn_notxholds;
enum dnode_dirtycontext dn_dirtyctx;
uint8_t *dn_dirtyctx_firstset; /* dbg: contents meaningless */
@ -406,6 +407,9 @@ void dnode_evict_bonus(dnode_t *dn);
void dnode_free_interior_slots(dnode_t *dn);
boolean_t dnode_needs_remap(const dnode_t *dn);
#define DNODE_IS_DIRTY(_dn) \
((_dn)->dn_dirty_txg >= spa_syncing_txg((_dn)->dn_objset->os_spa))
#define DNODE_IS_CACHEABLE(_dn) \
((_dn)->dn_objset->os_primary_cache == ZFS_CACHE_ALL || \
(DMU_OT_IS_METADATA((_dn)->dn_type) && \