zfs: cherry-pick commit from master

 #15571 30d581121 dnode_is_dirty: check dnode and its data for dirtiness

Obtained from:	OpenZFS

(cherry picked from commit 30d581121bb122c90959658e7b28b1672d342897)

1 files changed, 10 insertions, 2 deletions

diff --git a/sys/contrib/openzfs/module/zfs/dnode.c b/sys/contrib/openzfs/module/zfs/dnode.c
index a9aaa4d21d2b..efebc443a210 100644
--- a/sys/contrib/openzfs/module/zfs/dnode.c
+++ b/sys/contrib/openzfs/module/zfs/dnode.c
@@ -1773,7 +1773,14 @@ dnode_try_claim(objset_t *os, uint64_t object, int slots)
 }
 
 /*
- * Checks if the dnode contains any uncommitted dirty records.
+ * Checks if the dnode itself is dirty, or is carrying any uncommitted records.
+ * It is important to check both conditions, as some operations (eg appending
+ * to a file) can dirty both as a single logical unit, but they are not synced
+ * out atomically, so checking one and not the other can result in an object
+ * appearing to be clean mid-way through a commit.
+ *
+ * Do not change this lightly! If you get it wrong, dmu_offset_next() can
+ * detect a hole where there is really data, leading to silent corruption.
  */
 boolean_t
 dnode_is_dirty(dnode_t *dn)
@@ -1781,7 +1788,8 @@ dnode_is_dirty(dnode_t *dn)
 	mutex_enter(&dn->dn_mtx);
 
 	for (int i = 0; i < TXG_SIZE; i++) {
-		if (multilist_link_active(&dn->dn_dirty_link[i])) {
+		if (multilist_link_active(&dn->dn_dirty_link[i]) ||
+		    !list_is_empty(&dn->dn_dirty_records[i])) {
 			mutex_exit(&dn->dn_mtx);
 			return (B_TRUE);
 		}