diff --git a/kmod/src/count.h b/kmod/src/count.h
index b763cc2b..4198dbf5 100644
--- a/kmod/src/count.h
+++ b/kmod/src/count.h
@@ -54,7 +54,7 @@ static inline void scoutfs_count_dirents(struct scoutfs_item_count *cnt,
 static inline void scoutfs_count_sym_target(struct scoutfs_item_count *cnt,
 					      unsigned size)
 {
-	unsigned nr = DIV_ROUND_UP(size, SCOUTFS_SYMLINK_MAX_VAL_SIZE);
+	unsigned nr = DIV_ROUND_UP(size, SCOUTFS_MAX_VAL_SIZE);
 
 	cnt->items += nr;
 	cnt->keys += nr * sizeof(struct scoutfs_symlink_key);
diff --git a/kmod/src/dir.c b/kmod/src/dir.c
index 04461e75..52448cd5 100644
--- a/kmod/src/dir.c
+++ b/kmod/src/dir.c
@@ -661,7 +661,7 @@ enum {
 	SYM_DELETE,
 };
 static int symlink_item_ops(struct super_block *sb, int op, u64 ino,
-			    const char *target, int size)
+			    const char *target, size_t size)
 {
 	struct scoutfs_symlink_key skey;
 	struct scoutfs_key_buf key;
@@ -671,15 +671,15 @@ static int symlink_item_ops(struct super_block *sb, int op, u64 ino,
 	int ret;
 	int i;
 
-	if (WARN_ON_ONCE(size <= 0 || size > SCOUTFS_SYMLINK_MAX_SIZE ||
+	if (WARN_ON_ONCE(size == 0 || size > SCOUTFS_SYMLINK_MAX_SIZE ||
 		         op > SYM_DELETE))
 		return -EINVAL;
 
-	nr = DIV_ROUND_UP(size, SCOUTFS_SYMLINK_MAX_VAL_SIZE);
+	nr = DIV_ROUND_UP(size, SCOUTFS_MAX_VAL_SIZE);
 	for (i = 0; i < nr; i++) {
 
 		init_symlink_key(&key, &skey, ino, i);
-		bytes = min(size, SCOUTFS_SYMLINK_MAX_VAL_SIZE);
+		bytes = min(size, SCOUTFS_MAX_VAL_SIZE);
 		scoutfs_kvec_init(val, (void *)target, bytes);
 
 		if (op == SYM_CREATE)
@@ -691,7 +691,7 @@ static int symlink_item_ops(struct super_block *sb, int op, u64 ino,
 		if (ret)
 			break;
 
-		target += SCOUTFS_SYMLINK_MAX_VAL_SIZE;
+		target += SCOUTFS_MAX_VAL_SIZE;
 		size -= bytes;
 	}
 
diff --git a/kmod/src/format.h b/kmod/src/format.h
index fc36d50e..c511d51a 100644
--- a/kmod/src/format.h
+++ b/kmod/src/format.h
@@ -260,8 +260,6 @@ struct scoutfs_symlink_key {
 	__u8 nr;
 } __packed;
 
-#define SCOUTFS_SYMLINK_MAX_VAL_SIZE 200
-
 struct scoutfs_betimespec {
 	__be64 sec;
 	__be32 nsec;
@@ -377,13 +375,6 @@ struct scoutfs_dirent {
 /* S32_MAX avoids the (int) sign bit and might avoid sloppy bugs */
 #define SCOUTFS_LINK_MAX S32_MAX
 
-#define SCOUTFS_XATTR_MAX_NAME_LEN 255
-#define SCOUTFS_XATTR_MAX_SIZE 65536
-#define SCOUTFS_XATTR_PART_SIZE \
-	(SCOUTFS_BLOCK_SIZE - sizeof(struct scoutfs_xattr_val_header))
-#define SCOUTFS_XATTR_MAX_PARTS \
-	DIV_ROUND_UP(SCOUTFS_XATTR_MAX_SIZE, SCOUTFS_XATTR_PART_SIZE)
-
 /* entries begin after . and .. */
 #define SCOUTFS_DIRENT_FIRST_POS 2
 /* getdents returns next pos with an entry, no entry at (f_pos)~0 */
@@ -404,6 +395,18 @@ enum {
 #define SCOUTFS_MAX_KEY_SIZE \
 	offsetof(struct scoutfs_link_backref_key, name[SCOUTFS_NAME_LEN + 1])
 
+/* largest single val are dirents, larger broken up into units of this */
+#define SCOUTFS_MAX_VAL_SIZE \
+	offsetof(struct scoutfs_dirent, name[SCOUTFS_NAME_LEN])
+
+#define SCOUTFS_XATTR_MAX_NAME_LEN 255
+#define SCOUTFS_XATTR_MAX_SIZE 65536
+#define SCOUTFS_XATTR_PART_SIZE \
+	(SCOUTFS_MAX_VAL_SIZE - sizeof(struct scoutfs_xattr_val_header))
+#define SCOUTFS_XATTR_MAX_PARTS \
+	DIV_ROUND_UP(SCOUTFS_XATTR_MAX_SIZE, SCOUTFS_XATTR_PART_SIZE)
+
+
 /*
  * messages over the wire.
  */
diff --git a/kmod/src/item.c b/kmod/src/item.c
index 79b18f60..6135b0eb 100644
--- a/kmod/src/item.c
+++ b/kmod/src/item.c
@@ -41,6 +41,12 @@
  * clobber them in creation and skip them in lookups.
  */
 
+static bool invalid_key_val(struct scoutfs_key_buf *key, struct kvec *val)
+{
+	return WARN_ON_ONCE(key->key_len > SCOUTFS_MAX_KEY_SIZE ||
+	        (val && (scoutfs_kvec_length(val) > SCOUTFS_MAX_VAL_SIZE)));
+}
+
 static bool invalid_flags(int sif)
 {
 	return (sif & SIF_EXCLUSIVE) && (sif & SIF_REPLACE);
@@ -992,6 +998,9 @@ int scoutfs_item_create(struct super_block *sb, struct scoutfs_key_buf *key,
 	unsigned long flags;
 	int ret;
 
+	if (invalid_key_val(key, val))
+		return -EINVAL;
+
 	item = alloc_item(sb, key, val);
 	if (!item)
 		return -ENOMEM;
@@ -1021,6 +1030,9 @@ int scoutfs_item_add_batch(struct super_block *sb, struct list_head *list,
 	struct cached_item *item;
 	int ret;
 
+	if (invalid_key_val(key, val))
+		return -EINVAL;
+
 	item = alloc_item(sb, key, val);
 	if (item) {
 		list_add_tail(&item->entry, list);
@@ -1128,6 +1140,11 @@ int scoutfs_item_set_batch(struct super_block *sb, struct list_head *list,
 	if (WARN_ON_ONCE(invalid_flags(sif)))
 		return -EINVAL;
 
+	list_for_each_entry(item, list, entry) {
+		if (invalid_key_val(item->key, item->val))
+			return -EINVAL;
+	}
+
 	trace_scoutfs_item_set_batch(sb, start, end);
 
 	if (WARN_ON_ONCE(scoutfs_key_compare(start, end) > 0))
@@ -1283,6 +1300,9 @@ int scoutfs_item_update(struct super_block *sb, struct scoutfs_key_buf *key,
 	unsigned long flags;
 	int ret;
 
+	if (invalid_key_val(key, val))
+		return -EINVAL;
+
 	end = scoutfs_key_alloc(sb, SCOUTFS_MAX_KEY_SIZE);
 	if (!end) {
 		ret = -ENOMEM;