From 78e21394679ed7435f9b0d10a56ce4f679c680fe Mon Sep 17 00:00:00 2001 From: Brian Behlendorf Date: Wed, 5 Dec 2018 09:29:33 -0800 Subject: [PATCH] Fix dnode_hold() freeing dnode behavior Commit 4c5b89f59 refactored dnode_hold() and in the process accidentally introduced a slight change in behavior which was not intended. The required behavior is that once the ZPL, or other consumer, declares its intent to free a dnode then dnode_hold() should immediately start failing. This updated code wouldn't return the failure until after it was freed. When DNODE_MUST_BE_ALLOCATED is set it must return ENOENT, and when DNODE_MUST_BE_FREE is set it must return EEXIST; This issue was uncovered by ztest_remap() which attempted to remap a freeing object which should have been skipped as described by the comment in dmu_objset_remap_indirects_impl(). Reviewed-by: George Melikov Reviewed-by: Tom Caputi Reviewed-by: Olaf Faaland Signed-off-by: Brian Behlendorf Closes #8172 --- module/zfs/dnode.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/module/zfs/dnode.c b/module/zfs/dnode.c index 6b9f94053..0e9a4dabe 100644 --- a/module/zfs/dnode.c +++ b/module/zfs/dnode.c @@ -1253,8 +1253,10 @@ dnode_buf_evict_async(void *dbu) * EINVAL - Invalid object number or flags. * ENOSPC - Hole too small to fulfill "slots" request (DNODE_MUST_BE_FREE) * EEXIST - Refers to an allocated dnode (DNODE_MUST_BE_FREE) + * - Refers to a freeing dnode (DNODE_MUST_BE_FREE) * - Refers to an interior dnode slot (DNODE_MUST_BE_ALLOCATED) * ENOENT - The requested dnode is not allocated (DNODE_MUST_BE_ALLOCATED) + * - The requested dnode is being freed (DNODE_MUST_BE_ALLOCATED) * EIO - I/O error when reading the meta dnode dbuf. * * succeeds even for free dnodes. @@ -1443,7 +1445,7 @@ dnode_hold_impl(objset_t *os, uint64_t object, int flag, int slots, } mutex_enter(&dn->dn_mtx); - if (dn->dn_type == DMU_OT_NONE) { + if (dn->dn_type == DMU_OT_NONE || dn->dn_free_txg != 0) { DNODE_STAT_BUMP(dnode_hold_alloc_type_none); mutex_exit(&dn->dn_mtx); dnode_slots_rele(dnc, idx, slots); @@ -1502,7 +1504,7 @@ dnode_hold_impl(objset_t *os, uint64_t object, int flag, int slots, } mutex_enter(&dn->dn_mtx); - if (!zfs_refcount_is_zero(&dn->dn_holds)) { + if (!zfs_refcount_is_zero(&dn->dn_holds) || dn->dn_free_txg) { DNODE_STAT_BUMP(dnode_hold_free_refcount); mutex_exit(&dn->dn_mtx); dnode_slots_rele(dnc, idx, slots); -- 2.40.0