From 86063d90319ac8a785d81ba7e3f8037a7f5389f3 Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Tue, 12 Dec 2023 15:53:59 -0500 Subject: [PATCH] dbuf: Handle arcbuf assignment after block cloning In some cases dbuf_assign_arcbuf() may be called on a block that was recently cloned. If it happened in current TXG we must undo the block cloning first, since the only one dirty record per TXG can't and shouldn't mean both cloning and overwrite same time. Reviewed-by: Kay Pedersen Reviewed-by: Brian Behlendorf Signed-off-by: Alexander Motin Sponsored by: iXsystems, Inc. Closes #15653 --- module/zfs/dbuf.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c index c5ccd4cd1e..a07fe17335 100644 --- a/module/zfs/dbuf.c +++ b/module/zfs/dbuf.c @@ -2945,7 +2945,8 @@ dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx) while (db->db_state == DB_READ || db->db_state == DB_FILL) cv_wait(&db->db_changed, &db->db_mtx); - ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED); + ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED || + db->db_state == DB_NOFILL); if (db->db_state == DB_CACHED && zfs_refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) { @@ -2982,6 +2983,15 @@ dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx) arc_buf_destroy(db->db_buf, db); } db->db_buf = NULL; + } else if (db->db_state == DB_NOFILL) { + /* + * We will be completely replacing the cloned block. In case + * it was cloned in this transaction group, let's undirty the + * pending clone and mark the block as uncached. This will be + * as if the clone was never done. + */ + VERIFY(!dbuf_undirty(db, tx)); + db->db_state = DB_UNCACHED; } ASSERT(db->db_buf == NULL); dbuf_set_data(db, buf);