Revert "DLPX-79316 use exportfs finer grain cache control from libsha…

…re (openzfs#365)" (openzfs#460)

This reverts commit 66b2e0f.

lib/libshare/libshare.c

@@ -75,12 +75,6 @@ libshare_init(void)
 	libshare_smb_init();
 }
 
-__attribute__((destructor)) static void
-libshare_fini(void)
-{
-	libshare_nfs_fini();
-}
-
 int
 sa_enable_share(const char *zfsname, const char *mountpoint,
     const char *shareopts, char *protocol)

lib/libshare/nfs.h

@@ -29,7 +29,6 @@
 #define	FILE_HEADER		"# !!! DO NOT EDIT THIS FILE MANUALLY !!!\n\n"
 
 void libshare_nfs_init(void);
-void libshare_nfs_fini(void);
 
 boolean_t nfs_is_shared_impl(const char *exports, sa_share_impl_t impl_share);
 int nfs_toggle_share(const char *lockfile, const char *exports,

lib/libshare/os/linux/nfs.c

@@ -23,21 +23,18 @@
  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2011 Gunnar Beutner
  * Copyright (c) 2012 Cyril Plisko. All rights reserved.
- * Copyright (c) 2019, 2022 by Delphix. All rights reserved.
+ * Copyright (c) 2019, 2020 by Delphix. All rights reserved.
  */
 
 #include <dirent.h>
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
 #include <fcntl.h>
-#include <pthread.h>
-#include <stddef.h>
 #include <sys/file.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
-#include <sys/list.h>
 #include <unistd.h>
 #include <libzfs.h>
 #include <libshare.h>
@@ -48,8 +45,6 @@
 #define	ZFS_EXPORTS_FILE	ZFS_EXPORTS_DIR"/zfs.exports"
 #define	ZFS_EXPORTS_LOCK	ZFS_EXPORTS_FILE".lock"
 
-#define	EXPORTFS_PROG		"/usr/sbin/exportfs"
-
 static sa_fstype_t *nfs_fstype;
 
 typedef int (*nfs_shareopt_callback_t)(const char *opt, const char *value,
@@ -58,16 +53,6 @@ typedef int (*nfs_shareopt_callback_t)(const char *opt, const char *value,
 typedef int (*nfs_host_callback_t)(FILE *tmpfile, const char *sharepath,
     const char *host, const char *security, const char *access, void *cookie);
 
-static boolean_t exportfs_cache_control = B_FALSE;
-
-typedef struct unshared_dataset_entry {
-	list_node_t	ude_node;
-	char		ude_path[0];
-} unshared_dataset_entry_t;
-
-static pthread_mutex_t	unshared_dataset_lock;
-static list_t		unshared_dataset_list;
-
 /*
  * Invokes the specified callback function for each Solaris share option
  * listed in the specified string.
@@ -154,6 +139,10 @@ foreach_nfs_host_cb(const char *opt, const char *value, void *pcookie)
 	nfs_host_cookie_t *udata = (nfs_host_cookie_t *)pcookie;
 	int cidr_len;
 
+#ifdef DEBUG
+	fprintf(stderr, "foreach_nfs_host_cb: key=%s, value=%s\n", opt, value);
+#endif
+
 	if (strcmp(opt, "sec") == 0)
 		udata->security = value;
 
@@ -444,37 +433,13 @@ nfs_enable_share(sa_share_impl_t impl_share)
 	    nfs_enable_share_impl));
 }
 
-/*
- * Save the mountpoint so we can flush the rpc caches after
- * the shares are commited.
- */
-static int
-save_unshared_dataset(const char *mountpoint)
-{
-	pthread_mutex_lock(&unshared_dataset_lock);
-	unshared_dataset_entry_t *ude =
-	    malloc(sizeof (unshared_dataset_entry_t) +
-	    strlen(mountpoint) + 1);
-	if (ude == NULL)
-		return (SA_NO_MEMORY);
-	strcpy(ude->ude_path, mountpoint);
-	list_insert_tail(&unshared_dataset_list, ude);
-	pthread_mutex_unlock(&unshared_dataset_lock);
-
-	return (SA_OK);
-}
-
 /*
  * Disables NFS sharing for the specified share.
  */
 static int
 nfs_disable_share_impl(sa_share_impl_t impl_share, FILE *tmpfile)
 {
-	(void) tmpfile;
-
-	if (exportfs_cache_control)
-		return (save_unshared_dataset(impl_share->sa_mountpoint));
-
+	(void) impl_share, (void) tmpfile;
 	return (SA_OK);
 }
 
@@ -527,60 +492,16 @@ nfs_clear_shareopts(sa_share_impl_t impl_share)
 	FSINFO(impl_share, nfs_fstype)->shareopts = NULL;
 }
 
-static int
-exportfs_flush_cache_entry(char *mountpoint)
-{
-	ASSERT(exportfs_cache_control);
-
-	char *argv[] = {
-	    EXPORTFS_PROG,
-	    "-F",
-	    mountpoint,
-	    NULL
-	};
-
-	return (libzfs_run_process(argv[0], argv, 0));
-}
-
-static void
-flush_unshared_datasets(void)
-{
-	/*
-	 * After calling exportfs to reexport our shares we need to
-	 * flush the rpc cache entries for datasets that were unshared.
-	 */
-	unshared_dataset_entry_t *ude = NULL;
-	pthread_mutex_lock(&unshared_dataset_lock);
-	while ((ude = list_remove_head(&unshared_dataset_list)) != NULL) {
-		pthread_mutex_unlock(&unshared_dataset_lock);
-		exportfs_flush_cache_entry(ude->ude_path);
-		pthread_mutex_lock(&unshared_dataset_lock);
-		free(ude);
-	}
-	pthread_mutex_unlock(&unshared_dataset_lock);
-}
-
-/*
- * Reexport all directories including the ones maintained in our
- * '/etc/exports.d/zfs.exports' file. This will remove entries
- * that have been deleted from our exports file.
- */
 static int
 nfs_commit_shares(void)
 {
-	char *exportfs_args = exportfs_cache_control ? "-raN" : "-ra";
 	char *argv[] = {
-	    EXPORTFS_PROG,
-	    exportfs_args,
+	    "/usr/sbin/exportfs",
+	    "-ra",
 	    NULL
 	};
 
-	int rc = libzfs_run_process(argv[0], argv, 0);
-
-	if (exportfs_cache_control)
-		flush_unshared_datasets();
-
-	return (rc);
+	return (libzfs_run_process(argv[0], argv, 0));
 }
 
 static const sa_share_ops_t nfs_shareops = {
@@ -594,54 +515,11 @@ static const sa_share_ops_t nfs_shareops = {
 	.commit_shares = nfs_commit_shares,
 };
 
-static boolean_t
-cache_control_supported(void)
-{
-	char *argv[] = {EXPORTFS_PROG, "-vh", NULL};
-	char **lines = NULL;
-	int lines_cnt = 0;
-	int rc;
-	boolean_t supported;
-
-	/*
-	 * Expected output to confirm support for finer-grain cache flushing:
-	 *
-	 * $ exportfs -vh
-	 * supports: no_cache_flush,flush_one_entry
-	 * usage: exportfs [-adfFhiNoruvs] [host:/path]
-	 */
-	rc = libzfs_run_process_get_stdout_nopath(EXPORTFS_PROG, argv, NULL,
-	    &lines, &lines_cnt);
-	supported = (rc == 0 && lines_cnt > 0 &&
-	    strstr(lines[0], "no_cache_flush") != NULL);
-	libzfs_free_str_array(lines, lines_cnt);
-
-	return (supported);
-}
-
 /*
  * Initializes the NFS functionality of libshare.
  */
 void
 libshare_nfs_init(void)
 {
 	nfs_fstype = register_fstype("nfs", &nfs_shareops);
-
-	exportfs_cache_control = cache_control_supported();
-	if (exportfs_cache_control) {
-		pthread_mutex_init(&unshared_dataset_lock, NULL);
-		list_create(&unshared_dataset_list,
-		    sizeof (unshared_dataset_entry_t),
-		    offsetof(unshared_dataset_entry_t, ude_node));
-	}
-}
-
-void
-libshare_nfs_fini(void)
-{
-	if (exportfs_cache_control) {
-		ASSERT(list_is_empty(&unshared_dataset_list));
-		list_destroy(&unshared_dataset_list);
-		pthread_mutex_destroy(&unshared_dataset_lock);
-	}
 }