Index: fs/fuse/fuse_vnops.c
===================================================================
--- fs/fuse/fuse_vnops.c
+++ fs/fuse/fuse_vnops.c
@@ -2023,7 +2023,7 @@
 	 * fuse_getxattr_out.  If we pass in a non-zero size, we get back
 	 * that much data, without the struct fuse_getxattr_out header.
 	 */
-	if (ap->a_size != NULL)
+	if (uio == NULL)
 		get_xattr_in->size = 0;
 	else
 		get_xattr_in->size = uio->uio_resid;
@@ -2053,13 +2053,11 @@
 	}
 	get_xattr_out = fdi.answ;
 
-	if (ap->a_size != NULL) {
+	if (ap->a_size != NULL)
 		*ap->a_size = get_xattr_out->size;
-	} else if (fdi.iosize > 0) {
+
+	if (uio != NULL)
 		err = uiomove(fdi.answ, fdi.iosize, uio);
-	} else {
-		err = EINVAL;
-	}
 
 out:
 	fdisp_destroy(&fdi);
@@ -2216,7 +2214,9 @@
 	char *prefix;
 	char *attr_str;
 	char *bsd_list = NULL;
+	char *linux_list;
 	int bsd_list_len;
+	int linux_list_len;
 	struct thread *td = ap->a_td;
 	struct ucred *cred = ap->a_cred;
 	int err = 0;
@@ -2240,13 +2240,11 @@
 	fdisp_init(&fdi, sizeof(*get_xattr_in) + len);
 	fdisp_make_vp(&fdi, FUSE_LISTXATTR, vp, td, cred);
 
+	/*
+	 * Retrieve Linux / FUSE compatible list size.
+	 */
 	get_xattr_in = fdi.indata;
-	if (ap->a_size != NULL)
-		get_xattr_in->size = 0;
-	else
-		get_xattr_in->size = uio->uio_resid + sizeof(*get_xattr_out);
-
-
+	get_xattr_in->size = 0;
 	attr_str = (char *)fdi.indata + sizeof(*get_xattr_in);
 	snprintf(attr_str, len, "%s%c", prefix, extattr_namespace_separator);
 
@@ -2258,32 +2256,46 @@
 		goto out;
 	}
 
-	if ((fdi.answ == NULL) || (fdi.iosize == 0)) {
-		err = EINVAL;
+	get_xattr_out = fdi.answ;
+	linux_list_len = get_xattr_out->size;
+	if (linux_list_len == 0) {
+		if (ap->a_size != NULL)
+			*ap->a_size = linux_list_len;
 		goto out;
 	}
-	get_xattr_out = fdi.answ;
 
-	if (ap->a_size != NULL) {
-		*ap->a_size = get_xattr_out->size;
-	} else if (fdi.iosize > 0) {
-		/*
-		 * The Linux / FUSE attribute list format isn't the same
-		 * as FreeBSD's format.  So we need to transform it into
-		 * FreeBSD's format before giving it to the user.
-		 */
-		bsd_list = malloc(fdi.iosize, M_TEMP, M_WAITOK);
-		err = fuse_xattrlist_convert(prefix, fdi.answ, fdi.iosize,
-		    bsd_list, &bsd_list_len);
-		if (err != 0)
-			goto out;
+	/*
+	 * Retrieve Linux / FUSE compatible list values.
+	 */
+	fdisp_make_vp(&fdi, FUSE_LISTXATTR, vp, td, cred);
+	get_xattr_in->size = linux_list_len + sizeof(*get_xattr_out);
+	err = fdisp_wait_answ(&fdi);
+	if (err != 0) {
+		if (err == ENOSYS)
+			fsess_set_notimpl(mp, FUSE_LISTXATTR);
+		goto out;
+	}
 
+	linux_list = fdi.answ;
+	linux_list_len = fdi.iosize;
+
+	/*
+	 * Retrieve the BSD compatible list values.
+	 * The Linux / FUSE attribute list format isn't the same
+	 * as FreeBSD's format. So we need to transform it into
+	 * FreeBSD's format before giving it to the user.
+	 */
+	bsd_list = malloc(linux_list_len, M_TEMP, M_WAITOK);
+	err = fuse_xattrlist_convert(prefix, linux_list, linux_list_len,
+	    bsd_list, &bsd_list_len);
+	if (err != 0)
+		goto out;
+
+	if (ap->a_size != NULL)
+		*ap->a_size = bsd_list_len;
+
+	if (uio != NULL)
 		err = uiomove(bsd_list, bsd_list_len, uio);
-	} else {
-		debug_printf("listextattr: returned iosize %zu for %s attribute list is "
-		    "too small\n", fdi.iosize, prefix);
-		err = EINVAL;
-	}
 
 out:
 	free(bsd_list, M_TEMP);