ZAP: Fix leaf references on zap_expand_leaf() errors

Depending on kind of error zap_expand_leaf() may return with or without valid leaf reference held. Make sure it returns NULL if due to error it has no leaf to return. Make its callers to check the returned leaf pointer, and release the leaf if it is not NULL. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc. Closes openzfs#12366 Closes openzfs#16159
truenas · May 23, 2024 · d13f0bf · d13f0bf
1 parent 09d8243
commit d13f0bf
Showing 1 changed file with 14 additions and 13 deletions.
diff --git a/module/zfs/zap.c b/module/zfs/zap.c
@@ -635,6 +635,7 @@ zap_expand_leaf(zap_name_t *zn, zap_leaf_t *l,
 		uint64_t object = zap->zap_object;
 
 		zap_put_leaf(l);
+		*lp = l = NULL;
 		zap_unlockdir(zap, tag);
 		err = zap_lockdir(os, object, tx, RW_WRITER,
 		    FALSE, FALSE, tag, &zn->zn_zap);
@@ -844,21 +845,17 @@ fzap_add_cd(zap_name_t *zn,
 	} else if (err == EAGAIN) {
 		err = zap_expand_leaf(zn, l, tag, tx, &l);
 		zap = zn->zn_zap;	/* zap_expand_leaf() may change zap */
-		if (err == 0) {
+		if (err == 0)
 			goto retry;
-		} else if (err == ENOSPC) {
-			/*
-			 * If we failed to expand the leaf, then bailout
-			 * as there is no point trying
-			 * zap_put_leaf_maybe_grow_ptrtbl().
-			 */
-			return (err);
-		}
 	}
 
 out:
-	if (zap != NULL)
-		zap_put_leaf_maybe_grow_ptrtbl(zn, l, tag, tx);
+	if (l != NULL) {
+		if (err == ENOSPC)
+			zap_put_leaf(l);
+		else
+			zap_put_leaf_maybe_grow_ptrtbl(zn, l, tag, tx);
+	}
 	return (err);
 }
 
@@ -915,8 +912,12 @@ fzap_update(zap_name_t *zn,
 			goto retry;
 	}
 
-	if (zap != NULL)
-		zap_put_leaf_maybe_grow_ptrtbl(zn, l, tag, tx);
+	if (l != NULL) {
+		if (err == ENOSPC)
+			zap_put_leaf(l);
+		else
+			zap_put_leaf_maybe_grow_ptrtbl(zn, l, tag, tx);
+	}
 	return (err);
 }