sbin/hammer2/cmd_leaf.c

   1 /*
   2  * Copyright (c) 2011-2012 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@dragonflybsd.org>
   6  * by Venkatesh Srinivas <vsrinivas@dragonflybsd.org>
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in
  16  *    the documentation and/or other materials provided with the
  17  *    distribution.
  18  * 3. Neither the name of The DragonFly Project nor the names of its
  19  *    contributors may be used to endorse or promote products derived
  20  *    from this software without specific, prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  26  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include "hammer2.h"
  37
  38 /*
  39  * Start-up the leaf daemon for a PFS on this machine.
  40  *
  41  * One leaf daemon is run for each mounted PFS.  The daemon may multi-thread
  42  * to improve performance if desired.  The daemon performs the following
  43  * functions:
  44  *
  45  *      (1) Makes and maintains connections to all cluster nodes found for
  46  *          the PFS, retrieved from the REMOTE configuration stored in
  47  *          the HAMMER2 mount.  A localhost connection is always implied
  48  *          (using the backbone), but also having more direct connections
  49  *          can result in higher performance.
  50  *
  51  *          This also includes any required encryption or authentication.
  52  *
  53  *      (2) Runs the spanning tree protocol as a leaf, meaning that
  54  *          the leaf daemon does not serve as a relay and the individual
  55  *          connections made in (1) do not cross-connect.
  56  *
  57  *      (3) Obtains the PFS's registration and makes it available to the
  58  *          cluster via the spanning tree protocol.
  59  *
  60  *      (4) Creates a communications pipe to the HAMMER2 VFS in the kernel
  61  *          (installed via ioctl()) which the HAMMER2 VFS uses to accept and
  62  *          communicate high-level requests.
  63  *
  64  *      (5) Performs all complex high-level messaging protocol operations,
  65  *          such as quorum operations, maintains persistent cache state,
  66  *          and so on and so forth.
  67  *
  68  * As you may have noted, the leaf daemon serves as an intermediary between
  69  * the kernel and the rest of the cluster.  The kernel will issue high level
  70  * protocol commands to the leaf which performs the protocol and sends a
  71  * response.  The kernel does NOT have to deal with the quorum or other
  72  * complex maintainance.
  73  *
  74  * Basically the kernel is simply another client from the point of view
  75  * of the high-level protocols, requesting cache state locks and such from
  76  * the leaf (in a degenerate situation one master lock is all that is needed).
  77  * If the kernel PFS has local media storage that storage can be used for
  78  * numerous purposes, such as caching, and in the degenerate non-clustered
  79  * case simply represents the one-and-only master copy of the filesystem.
  80  */
  81 int
  82 cmd_leaf(const char *sel_info)
  83 {
  84         int ecode = 0;
  85         int fd;
  86
  87         /*
  88          * Obtain an ioctl descriptor and retrieve the registration info
  89          * for the PFS.
  90          */
  91         if ((fd = hammer2_ioctl_handle(sel_info)) < 0)
  92                 return(1);
  93
  94         /*
  95          * Start a daemon to interconnect the HAMMER2 PFS in-kernel to the
  96          * master-node daemon.  This daemon's thread will spend most of its
  97          * time in the kernel.
  98          */
  99 /*      hammer2_demon(helper_pfs_interlink, (void *)(intptr_t)fd);*/
 100         if (NormalExit)
 101                 close(fd);
 102
 103         return ecode;
 104 }
 105
 106 #if 0
 107 /*
 108  * LEAF interconnect between PFS and the messaging core.  We create a
 109  * socket connection to the messaging core, register the PFS with the
 110  * core, and then pass the messaging descriptor to the kernel.
 111  *
 112  * The kernel takes over operation of the interconnect until the filesystem
 113  * is unmounted or the descriptor is lost or explicitly terminated via
 114  * a hammer2 command.
 115  *
 116  * This is essentially a localhost connection, so we don't have to worry
 117  * about encryption.  Any encryption will be handled by the messaging
 118  * core.
 119  */
 120 static
 121 void *
 122 leaf_connect(void *data)
 123 {
 124         int fd;
 125
 126         fd = (int)(intptr_t)data;
 127
 128         return (NULL);
 129 }
 130 #endif