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zfsonlinux/zfs-patches/0005-Fix-race-in-dnode_check_slots_free.patch
Stoiko Ivanov ff03aa2dfd cherry-pick 2 patches planned for zfs-0.7.12 
both patches have been backported and approved upstream, and will end up in
0.7.12.

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
2018-10-30 14:24:19 +01:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Tom Caputi <tcaputi@datto.com>
Date: Tue, 10 Apr 2018 14:15:05 -0400
Subject: [PATCH] Fix race in dnode_check_slots_free()
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.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Requires-spl: spl-0.7-release
Issue #7147
Issue #7388
Issue #7997
(cherry-picked from behlendorf/issue-7997 4764f6f3be90be073d2700653dff286371e52583)
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
include/sys/dmu_impl.h | 1 +
include/sys/dnode.h | 4 ++++
module/zfs/dbuf.c | 3 +++
module/zfs/dmu.c | 2 +-
module/zfs/dmu_objset.c | 15 +++++++++++++++
module/zfs/dnode.c | 29 +++++++++++++++++++----------
6 files changed, 43 insertions(+), 11 deletions(-)
diff --git a/include/sys/dmu_impl.h b/include/sys/dmu_impl.h
index 65e417e3..03a63077 100644
--- a/include/sys/dmu_impl.h
+++ b/include/sys/dmu_impl.h
@@ -161,6 +161,7 @@ extern "C" {
* dn_allocated_txg
* dn_free_txg
* dn_assigned_txg
+ * dn_dirty_txg
* dd_assigned_tx
* dn_notxholds
* dn_dirtyctx
diff --git a/include/sys/dnode.h b/include/sys/dnode.h
index ea7defe1..2dd087b3 100644
--- a/include/sys/dnode.h
+++ b/include/sys/dnode.h
@@ -260,6 +260,7 @@ 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 */
@@ -362,6 +363,9 @@ void dnode_evict_dbufs(dnode_t *dn);
void dnode_evict_bonus(dnode_t *dn);
void dnode_free_interior_slots(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) && \
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c
index 4ee121f5..6edb39d6 100644
--- a/module/zfs/dbuf.c
+++ b/module/zfs/dbuf.c
@@ -1606,6 +1606,9 @@ 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)
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index 6f09aa2f..a09ac4f9 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -2044,7 +2044,7 @@ dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole, uint64_t *off)
* Check if dnode is dirty
*/
for (i = 0; i < TXG_SIZE; i++) {
- if (list_link_active(&dn->dn_dirty_link[i])) {
+ if (multilist_link_active(&dn->dn_dirty_link[i])) {
clean = B_FALSE;
break;
}
diff --git a/module/zfs/dmu_objset.c b/module/zfs/dmu_objset.c
index 449ebedf..0bed2d3e 100644
--- a/module/zfs/dmu_objset.c
+++ b/module/zfs/dmu_objset.c
@@ -1213,10 +1213,23 @@ 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);
@@ -1621,6 +1634,8 @@ 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);
diff --git a/module/zfs/dnode.c b/module/zfs/dnode.c
index d465b545..4a169c49 100644
--- a/module/zfs/dnode.c
+++ b/module/zfs/dnode.c
@@ -137,7 +137,7 @@ 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),
@@ -147,6 +147,7 @@ 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;
@@ -184,7 +185,7 @@ 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]);
@@ -199,6 +200,7 @@ 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);
@@ -523,6 +525,7 @@ 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) {
@@ -592,6 +595,7 @@ dnode_allocate(dnode_t *dn, dmu_object_type_t ot, int blocksize, int ibs,
ASSERT0(dn->dn_maxblkid);
ASSERT0(dn->dn_allocated_txg);
ASSERT0(dn->dn_assigned_txg);
+ ASSERT0(dn->dn_dirty_txg);
ASSERT(refcount_is_zero(&dn->dn_tx_holds));
ASSERT3U(refcount_count(&dn->dn_holds), <=, 1);
ASSERT(avl_is_empty(&dn->dn_dbufs));
@@ -604,7 +608,7 @@ 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);
}
@@ -779,6 +783,7 @@ 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);
@@ -845,6 +850,7 @@ 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;
@@ -1069,6 +1075,10 @@ 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;
@@ -1077,18 +1087,17 @@ 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 &&
+ !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);
@@ -1594,7 +1603,7 @@ 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;
}
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