lib/libvtreefs/vtreefs.c

   1 /* VTreeFS - vtreefs.c - by Alen Stojanov and David van Moolenbroek */
   2
   3 #include "inc.h"
   4
   5 static int get_work(void);
   6 static void send_reply(int err, int transid);
   7 static void got_signal(int signal);
   8
   9 static unsigned int inodes;
  10 static struct inode_stat *root_stat;
  11 static index_t root_entries;
  12
  13 /*===========================================================================*
  14  *                              init_server                                  *
  15  *===========================================================================*/
  16 static int init_server(int UNUSED(type), sef_init_info_t *UNUSED(info))
  17 {
  18         /* Initialize internal state, and register with VFS.
  19          */
  20
  21         /* Initialize the virtual tree. */
  22         init_inodes(inodes, root_stat, root_entries);
  23
  24         /* Do not yet allow any requests except REQ_READSUPER. */
  25         fs_mounted = FALSE;
  26
  27         return OK;
  28 }
  29
  30 /*===========================================================================*
  31  *                              sef_local_startup                            *
  32  *===========================================================================*/
  33 static void sef_local_startup(void)
  34 {
  35         sef_setcb_init_fresh(init_server);
  36         sef_setcb_init_restart(init_server);
  37
  38         sef_setcb_signal_handler(got_signal);
  39
  40         /* No support for live update yet. */
  41
  42         sef_startup();
  43 }
  44
  45 /*===========================================================================*
  46  *                              start_vtreefs                                *
  47  *===========================================================================*/
  48 void start_vtreefs(struct fs_hooks *hooks, unsigned int nr_inodes,
  49                 struct inode_stat *stat, index_t nr_indexed_entries)
  50 {
  51         /* This is the main routine of this service. The main loop consists of
  52          * three major activities: getting new work, processing the work, and
  53          * sending the reply. The loop exits when the process is signaled to
  54          * exit; due to limitations of SEF, it can not return to the caller.
  55          */
  56         int call_nr, err, transid;
  57
  58         /* Use global variables to work around the inability to pass parameters
  59          * through SEF to the initialization function..
  60          */
  61         vtreefs_hooks = hooks;
  62         inodes = nr_inodes;
  63         root_stat = stat;
  64         root_entries = nr_indexed_entries;
  65
  66         sef_local_startup();
  67
  68         for (;;) {
  69                 get_work();
  70
  71                 transid = TRNS_GET_ID(fs_m_in.m_type);
  72                 fs_m_in.m_type = TRNS_DEL_ID(fs_m_in.m_type);
  73                 if (fs_m_in.m_type == 0) {
  74                         assert(!IS_VFS_FS_TRANSID(transid));
  75                         fs_m_in.m_type = transid;       /* Backwards compat. */
  76                         transid = 0;
  77                 } else
  78                         assert(IS_VFS_FS_TRANSID(transid));
  79
  80                 call_nr = fs_m_in.m_type;
  81
  82                 if (fs_m_in.m_source != VFS_PROC_NR) {
  83                         if (vtreefs_hooks->message_hook != NULL) {
  84                                 /* If the request is not among the recognized
  85                                  * requests, call the message hook.
  86                                  */
  87                                 vtreefs_hooks->message_hook(&fs_m_in);
  88                         }
  89
  90                         continue;
  91                 }
  92
  93                 if (fs_mounted || call_nr == REQ_READSUPER) {
  94                         call_nr -= VFS_BASE;
  95
  96                         if (call_nr >= 0 && call_nr < NREQS) {
  97                                 err = (*fs_call_vec[call_nr])();
  98                         } else {
  99                                 err = ENOSYS;
 100                         }
 101                 }
 102                 else err = EINVAL;
 103
 104                 send_reply(err, transid);
 105         }
 106 }
 107
 108 /*===========================================================================*
 109  *                              get_work                                     *
 110  *===========================================================================*/
 111 static int get_work(void)
 112 {
 113         /* Retrieve work. Return the call number.
 114          */
 115         int r;
 116
 117         if ((r = sef_receive(ANY, &fs_m_in)) != OK)
 118                 panic(__FILE__, "receive failed", r);
 119
 120         return fs_m_in.m_type;
 121 }
 122
 123 /*===========================================================================*
 124  *                              send_reply                                   *
 125  *===========================================================================*/
 126 static void send_reply(int err, int transid)
 127 {
 128         /* Send a reply to the caller.
 129          */
 130         int r;
 131
 132         fs_m_out.m_type = err;
 133         if (IS_VFS_FS_TRANSID(transid)) {
 134                 fs_m_out.m_type = TRNS_ADD_ID(fs_m_out.m_type, transid);
 135         }
 136
 137         if ((r = send(fs_m_in.m_source, &fs_m_out)) != OK)
 138                 panic(__FILE__, "unable to send reply", r);
 139 }
 140
 141 /*===========================================================================*
 142  *                              got_signal                                   *
 143  *===========================================================================*/
 144 static void got_signal(int signal)
 145 {
 146         /* We received a signal. If it is a termination signal, and the file
 147          * system has already been unmounted, clean up and exit.
 148          */
 149
 150         if (signal != SIGTERM)
 151                 return;
 152
 153         if (fs_mounted)
 154                 return;
 155
 156         cleanup_inodes();
 157
 158         exit(0);
 159 }