NEX-16159 Time spent sharing SMB filesystems could be reduced by optimizing smb_getdataset for default mount points (lint fix)
Reviewed by: Jean McCormack <jean.mccormack@nexenta.com>
NEX-16159 Time spent sharing SMB filesystems could be reduced by optimizing smb_getdataset for default mount points
Reviewed by: Sanjay Nadkarni <sanjay.nadkarni@nexenta.com>
Reviewed by: Evan Layton <evan.layton@nexenta.com>
Reviewed by: Reviewed by: Matt Barden <matt.barden@nexenta.com>
NEX-2346 SMB server debug logging cleanup after NEX-2314
NEX-816 smbadm dumps core during first join attempt
SMB-50 User-mode SMB server
 Includes work by these authors:
 Thomas Keiser <thomas.keiser@nexenta.com>
 Albert Lee <trisk@nexenta.com>
re #12435 rb3958 r10 is added 2 times to panic info
re #12393 rb3935 Kerberos and smbd disagree about who is our AD server

*** 18,28 ****
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2014 Nexenta Systems, Inc.  All rights reserved.
   */
  
  #include <ctype.h>
  #include <stdio.h>
  #include <stdarg.h>
--- 18,28 ----
   *
   * CDDL HEADER END
   */
  /*
   * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2018 Nexenta Systems, Inc.  All rights reserved.
   */
  
  #include <ctype.h>
  #include <stdio.h>
  #include <stdarg.h>
*** 625,643 ****
   * Returns,
   *      0  = On success.
   *      -1 = Failure to open /etc/mnttab file or to get ZFS dataset.
   */
  int
! smb_getdataset(const char *path, char *dataset, size_t len)
  {
          char tmppath[MAXPATHLEN];
          char *cp;
          FILE *fp;
          struct mnttab mnttab;
          struct mnttab mntpref;
          int rc = -1;
  
          if ((fp = fopen(MNTTAB, "r")) == NULL)
                  return (-1);
  
          (void) memset(&mnttab, '\0', sizeof (mnttab));
          (void) strlcpy(tmppath, path, MAXPATHLEN);
--- 625,671 ----
   * Returns,
   *      0  = On success.
   *      -1 = Failure to open /etc/mnttab file or to get ZFS dataset.
   */
  int
! smb_getdataset(libzfs_handle_t *libhdl, const char *path, char *dataset,
!     size_t len)
  {
          char tmppath[MAXPATHLEN];
          char *cp;
          FILE *fp;
          struct mnttab mnttab;
          struct mnttab mntpref;
          int rc = -1;
  
+         /*
+          * Optimisation: if the path is the default mountpoint then
+          * the dataset name can be determined from path.
+          * Attempt to open dataset by derived name and, if successful,
+          * check if its mountpoint matches path.
+          */
+         if (libhdl != NULL) {
+                 zfs_handle_t *hdl;
+                 char mountpnt[ZFS_MAXPROPLEN];
+                 char *dsname = (char *)path + strspn(path, "/");
+ 
+                 hdl = zfs_open(libhdl, dsname, ZFS_TYPE_FILESYSTEM);
+                 if (hdl != NULL) {
+                         if ((zfs_prop_get(hdl, ZFS_PROP_MOUNTPOINT, mountpnt,
+                             sizeof (mountpnt), NULL, NULL, 0, B_FALSE) == 0) &&
+                             (strcmp(mountpnt, path) == 0)) {
+                                 zfs_close(hdl);
+                                 (void) strlcpy(dataset, dsname, len);
+                                 return (0);
+                         }
+                         zfs_close(hdl);
+                 }
+         }
+ 
+         /*
+          * Couldn't find a filesystem optimistically, use mnttab
+          */
          if ((fp = fopen(MNTTAB, "r")) == NULL)
                  return (-1);
  
          (void) memset(&mnttab, '\0', sizeof (mnttab));
          (void) strlcpy(tmppath, path, MAXPATHLEN);