NEX-16219 pool import performance regression due to repeated libshare…

… initialization

Reviewd by: Sanjay Nadkarni <sanjay.nadkarni@nexenta.com>
Reviewed by: Evan Layton <evan.layton@nexenta.com>

usr/src/cmd/zfs/zfs_main.c

@@ -6634,7 +6634,7 @@ unshare_unmount(int op, int argc, char **argv)
 
 		/*
 		 * Initilialize libshare SA_INIT_SHARE_API_SELECTIVE here
-		 * to avoid unneccesary load/unload of the libshare plugins
+		 * to avoid unneccesary load/unload of the libshare API
 		 * per shared dataset downstream.
 		 */
 		if (op == OP_SHARE) {

usr/src/lib/libshare/common/libshare.c

@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
+ * Copyright 2018 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2016 by Delphix. All rights reserved.
  */
 
@@ -1152,6 +1152,20 @@ sa_fini(sa_handle_t handle)
 	}
 }
 
+/*
+ * sa_service(sa_handle_t handle)
+ *
+ * Returns the service for which the handle is currently initialized.
+ */
+int
+sa_service(sa_handle_t handle)
+{
+	if (handle == NULL)
+		return (0);
+
+	return (((sa_handle_impl_t)handle)->sa_service);
+}
+
 /*
  * sa_get_protocols(char **protocol)
  *	Get array of protocols that are supported

usr/src/lib/libshare/common/libshare.h

@@ -21,7 +21,7 @@
 
 /*
  * Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
+ * Copyright 2018 Nexenta Systems, Inc.  All rights reserved.
  * Copyright (c) 2016 by Delphix. All rights reserved.
  */
 
@@ -171,6 +171,8 @@ typedef struct sa_init_selective_arg sa_init_selective_arg_t;
 extern sa_handle_t sa_init(int);
 extern sa_handle_t sa_init_arg(int, void *);
 extern void sa_fini(sa_handle_t);
+extern int sa_service(sa_handle_t);
+
 extern int sa_update_config(sa_handle_t);
 extern boolean_t sa_needs_refresh(sa_handle_t);
 extern char *sa_errorstr(int);

usr/src/lib/libshare/common/mapfile-vers

@@ -21,6 +21,7 @@
 #
 # Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved.
 # Copyright (c) 2016 by Delphix. All rights reserved.
+# Copyright 2018 Nexenta Systems, Inc.  All rights reserved.
 #
 
 #
@@ -114,6 +115,7 @@ SYMBOL_VERSION SUNWprivate {
 	sa_get_protocol_status;
 	sa_init;
 	sa_init_arg;
+	sa_service;
 	sa_find_share;
 	sa_set_protocol_property;
 	sa_fini;

usr/src/lib/libzfs/common/libzfs_mount.c

@@ -575,6 +575,7 @@ zfs_is_shared_smb(zfs_handle_t *zhp, char **where)
 
 static sa_handle_t (*_sa_init)(int);
 static sa_handle_t (*_sa_init_arg)(int, void *);
+static int (*_sa_service)(sa_handle_t);
 static void (*_sa_fini)(sa_handle_t);
 static sa_share_t (*_sa_find_share)(sa_handle_t, char *);
 static int (*_sa_enable_share)(sa_share_t, char *);
@@ -617,6 +618,8 @@ _zfs_init_libshare(void)
 		_sa_init_arg = (sa_handle_t (*)(int, void *))dlsym(libshare,
 		    "sa_init_arg");
 		_sa_fini = (void (*)(sa_handle_t))dlsym(libshare, "sa_fini");
+		_sa_service = (int (*)(sa_handle_t))dlsym(libshare,
+		    "sa_service");
 		_sa_find_share = (sa_share_t (*)(sa_handle_t, char *))
 		    dlsym(libshare, "sa_find_share");
 		_sa_enable_share = (int (*)(sa_share_t, char *))dlsym(libshare,
@@ -640,10 +643,11 @@ _zfs_init_libshare(void)
 		    _sa_enable_share == NULL || _sa_disable_share == NULL ||
 		    _sa_errorstr == NULL || _sa_parse_legacy_options == NULL ||
 		    _sa_needs_refresh == NULL || _sa_get_zfs_handle == NULL ||
-		    _sa_zfs_process_share == NULL ||
+		    _sa_zfs_process_share == NULL || _sa_service == NULL ||
 		    _sa_update_sharetab_ts == NULL) {
 			_sa_init = NULL;
 			_sa_init_arg = NULL;
+			_sa_service = NULL;
 			_sa_fini = NULL;
 			_sa_disable_share = NULL;
 			_sa_enable_share = NULL;
@@ -802,11 +806,25 @@ zfs_share_proto(zfs_handle_t *zhp, zfs_share_proto_t *proto)
 	sa_share_t share;
 	zfs_share_proto_t *curr_proto;
 	zprop_source_t sourcetype;
+	int service = SA_INIT_ONE_SHARE_FROM_HANDLE;
 	int ret;
 
 	if (!zfs_is_mountable(zhp, mountpoint, sizeof (mountpoint), NULL))
 		return (0);
 
+	/*
+	 * Function may be called in a loop from higher up stack, with libshare
+	 * initialized for multiple shares (SA_INIT_SHARE_API_SELECTIVE).
+	 * zfs_init_libshare_arg will refresh the handle's cache if necessary.
+	 * In this case we do not want to switch to per share initialization.
+	 * Specify SA_INIT_SHARE_API to do full refresh, if refresh required.
+	 */
+	if ((hdl->libzfs_sharehdl != NULL) && (_sa_service != NULL) &&
+	    (_sa_service(hdl->libzfs_sharehdl) ==
+	    SA_INIT_SHARE_API_SELECTIVE)) {
+		service = SA_INIT_SHARE_API;
+	}
+
 	for (curr_proto = proto; *curr_proto != PROTO_END; curr_proto++) {
 		/*
 		 * Return success if there are no share options.
@@ -816,8 +834,7 @@ zfs_share_proto(zfs_handle_t *zhp, zfs_share_proto_t *proto)
 		    ZFS_MAXPROPLEN, B_FALSE) != 0 ||
 		    strcmp(shareopts, "off") == 0)
 			continue;
-		ret = zfs_init_libshare_arg(hdl, SA_INIT_ONE_SHARE_FROM_HANDLE,
-		    zhp);
+		ret = zfs_init_libshare_arg(hdl, service, zhp);
 		if (ret != SA_OK) {
 			(void) zfs_error_fmt(hdl, EZFS_SHARENFSFAILED,
 			    dgettext(TEXT_DOMAIN, "cannot share '%s': %s"),
@@ -911,6 +928,7 @@ unshare_one(libzfs_handle_t *hdl, const char *name, const char *mountpoint,
 	sa_share_t share;
 	int err;
 	char *mntpt;
+	int service = SA_INIT_ONE_SHARE_FROM_NAME;
 
 	/*
 	 * Mountpoint could get trashed if libshare calls getmntany
@@ -920,13 +938,20 @@ unshare_one(libzfs_handle_t *hdl, const char *name, const char *mountpoint,
 	mntpt = zfs_strdup(hdl, mountpoint);
 
 	/*
-	 * make sure libshare initialized, initialize everything because we
-	 * don't know what other unsharing may happen later. Functions up the
-	 * stack are allowed to initialize instead a subset of shares at the
-	 * time the set is known.
+	 * Function may be called in a loop from higher up stack, with libshare
+	 * initialized for multiple shares (SA_INIT_SHARE_API_SELECTIVE).
+	 * zfs_init_libshare_arg will refresh the handle's cache if necessary.
+	 * In this case we do not want to switch to per share initialization.
+	 * Specify SA_INIT_SHARE_API to do full refresh, if refresh required.
 	 */
-	if ((err = zfs_init_libshare_arg(hdl, SA_INIT_ONE_SHARE_FROM_NAME,
-	    (void *)name)) != SA_OK) {
+	if ((hdl->libzfs_sharehdl != NULL) && (_sa_service != NULL) &&
+	    (_sa_service(hdl->libzfs_sharehdl) ==
+	    SA_INIT_SHARE_API_SELECTIVE)) {
+		service = SA_INIT_SHARE_API;
+	}
+
+	err = zfs_init_libshare_arg(hdl, service, (void *)name);
+	if (err != SA_OK) {
 		free(mntpt);	/* don't need the copy anymore */
 		return (zfs_error_fmt(hdl, proto_table[proto].p_unshare_err,
 		    dgettext(TEXT_DOMAIN, "cannot unshare '%s': %s"),
@@ -1678,7 +1703,7 @@ zpool_enable_datasets_ex(zpool_handle_t *zhp, const char *mntopts, int flags,
 
 	/*
 	 * Initilialize libshare SA_INIT_SHARE_API_SELECTIVE here
-	 * to avoid unneccesary load/unload of the libshare plugins
+	 * to avoid unneccesary load/unload of the libshare API
 	 * per shared dataset downstream.
 	 */
 	sharearg.zhandle_arr = cb.cb_handles;