From a701548eb4a8ed47ebda9b28a23e1de80adf1b91 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 5a7fe42b6..7691cd85f 100644 --- a/module/zfs/dbuf.c +++ b/module/zfs/dbuf.c @@ -2930,7 +2930,8 @@ 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) { @@ -2967,6 +2968,15 @@ 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);