FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_kern.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 2002 Poul-Henning Kamp
      * Copyright (c) 2002 Networks Associates Technology, Inc.
      * All rights reserved.
      *
      * This software was developed for the FreeBSD Project by Poul-Henning Kamp
      * and NAI Labs, the Security Research Division of Network Associates, Inc.
     * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
     * DARPA CHATS research program.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. The names of the authors may not be used to endorse or promote
     *    products derived from this software without specific prior written
     *    permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/eventhandler.h>
    #include <sys/malloc.h>
    #include <sys/bio.h>
    #include <sys/sysctl.h>
    #include <sys/proc.h>
    #include <sys/unistd.h>
    #include <sys/kthread.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/sbuf.h>
    #include <sys/sched.h>
    #include <sys/sx.h>
    #include <geom/geom.h>
    #include <geom/geom_int.h>
    
    MALLOC_DEFINE(M_GEOM, "GEOM", "Geom data structures");
    
    struct sx topology_lock;
    
    static struct proc *g_proc;
    static struct thread __read_mostly *g_up_td;
    static struct thread __read_mostly *g_down_td;
    static struct thread __read_mostly *g_event_td;
    
    int __read_mostly g_debugflags;
    int __read_mostly g_collectstats = G_STATS_PROVIDERS;
    int g_shutdown;
    int g_notaste;
    
    /*
     * G_UP and G_DOWN are the two threads which push I/O through the
     * stack.
     *
     * Things are procesed in a FIFO order, but these threads could be
     * part of I/O prioritization by deciding which bios/bioqs to service
     * in what order.
     *
     * We have only one thread in each direction, it is believed that until
     * a very non-trivial workload in the UP/DOWN path this will be enough,
     * but more than one can actually be run without problems.
     *
     * Holding the "mymutex" is a debugging feature:  It prevents people
     * from sleeping in the UP/DOWN I/O path by mistake or design (doing
     * so almost invariably result in deadlocks since it stalls all I/O
     * processing in the given direction.
     */
    
    static void
    g_up_procbody(void *arg)
    {
    
            thread_lock(g_up_td);
            sched_prio(g_up_td, PRIBIO);
            thread_unlock(g_up_td);
            for(;;) {
                    g_io_schedule_up(g_up_td);
           }
   }
   
   static void
   g_down_procbody(void *arg)
   {
   
           thread_lock(g_down_td);
           sched_prio(g_down_td, PRIBIO);
           thread_unlock(g_down_td);
           for(;;) {
                   g_io_schedule_down(g_down_td);
           }
   }
   
   static void
   g_event_procbody(void *arg)
   {
   
           thread_lock(g_event_td);
           sched_prio(g_event_td, PRIBIO);
           thread_unlock(g_event_td);
           g_run_events();
           /* NOTREACHED */
   }
   
   int
   g_is_geom_thread(struct thread *td)
   {
   
           return (td == g_up_td || td == g_down_td || td == g_event_td);
   }
   
   static void
   geom_shutdown(void *foo __unused)
   {
   
           g_shutdown = 1;
   }
   
   void
   g_init(void)
   {
   
           g_trace(G_T_TOPOLOGY, "g_ignition");
           sx_init(&topology_lock, "GEOM topology");
           g_io_init();
           g_event_init();
           g_ctl_init();
           kproc_kthread_add(g_event_procbody, NULL, &g_proc, &g_event_td,
               RFHIGHPID, 0, "geom", "g_event");
           kproc_kthread_add(g_up_procbody, NULL, &g_proc, &g_up_td,
               RFHIGHPID, 0, "geom", "g_up");
           kproc_kthread_add(g_down_procbody, NULL, &g_proc, &g_down_td,
               RFHIGHPID, 0, "geom", "g_down");
           EVENTHANDLER_REGISTER(shutdown_pre_sync, geom_shutdown, NULL,
                   SHUTDOWN_PRI_FIRST);
   }
   
   static int
   sysctl_kern_geom_confany(struct sysctl_req *req, g_event_t *func, size_t *hint)
   {
           size_t len = 0;
           int error = 0;
           struct sbuf *sb;
   
           if (req->oldptr == NULL) {
                   sb = sbuf_new(NULL, NULL, PAGE_SIZE, SBUF_FIXEDLEN |
                       SBUF_INCLUDENUL);
                   sbuf_set_drain(sb, sbuf_count_drain, &len);
                   g_waitfor_event(func, sb, M_WAITOK, NULL);
                   req->oldidx = *hint = len;
           } else {
                   sb = sbuf_new(NULL, NULL, *hint, SBUF_AUTOEXTEND |
                       SBUF_INCLUDENUL);
                   g_waitfor_event(func, sb, M_WAITOK, NULL);
                   *hint = sbuf_len(sb);
                   error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb));
           }
           sbuf_delete(sb);
           return error;
   }
   
   static int
   sysctl_kern_geom_conftxt(SYSCTL_HANDLER_ARGS)
   {
           static size_t hint = PAGE_SIZE;
   
           return (sysctl_kern_geom_confany(req, g_conftxt, &hint));
   }
    
   static int
   sysctl_kern_geom_confdot(SYSCTL_HANDLER_ARGS)
   {
           static size_t hint = PAGE_SIZE;
   
           return (sysctl_kern_geom_confany(req, g_confdot, &hint));
   }
   
   static int
   sysctl_kern_geom_confxml(SYSCTL_HANDLER_ARGS)
   {
           static size_t hint = PAGE_SIZE;
   
           return (sysctl_kern_geom_confany(req, g_confxml, &hint));
   }
   
   SYSCTL_NODE(_kern, OID_AUTO, geom, CTLFLAG_RW, 0, "GEOMetry management");
   
   SYSCTL_PROC(_kern_geom, OID_AUTO, confxml, CTLTYPE_STRING|CTLFLAG_RD,
           0, 0, sysctl_kern_geom_confxml, "",
           "Dump the GEOM config in XML");
   
   SYSCTL_PROC(_kern_geom, OID_AUTO, confdot, CTLTYPE_STRING|CTLFLAG_RD,
           0, 0, sysctl_kern_geom_confdot, "",
           "Dump the GEOM config in dot");
   
   SYSCTL_PROC(_kern_geom, OID_AUTO, conftxt, CTLTYPE_STRING|CTLFLAG_RD,
           0, 0, sysctl_kern_geom_conftxt, "",
           "Dump the GEOM config in txt");
   
   SYSCTL_INT(_kern_geom, OID_AUTO, debugflags, CTLFLAG_RWTUN,
           &g_debugflags, 0, "Set various trace levels for GEOM debugging");
   
   SYSCTL_INT(_kern_geom, OID_AUTO, notaste, CTLFLAG_RW,
           &g_notaste, 0, "Prevent GEOM tasting");
   
   SYSCTL_INT(_kern_geom, OID_AUTO, collectstats, CTLFLAG_RW,
           &g_collectstats, 0,
           "Control statistics collection on GEOM providers and consumers");
   
   SYSCTL_INT(_debug_sizeof, OID_AUTO, g_class, CTLFLAG_RD,
           SYSCTL_NULL_INT_PTR, sizeof(struct g_class), "sizeof(struct g_class)");
   SYSCTL_INT(_debug_sizeof, OID_AUTO, g_geom, CTLFLAG_RD,
           SYSCTL_NULL_INT_PTR, sizeof(struct g_geom), "sizeof(struct g_geom)");
   SYSCTL_INT(_debug_sizeof, OID_AUTO, g_provider, CTLFLAG_RD,
           SYSCTL_NULL_INT_PTR, sizeof(struct g_provider), "sizeof(struct g_provider)");
   SYSCTL_INT(_debug_sizeof, OID_AUTO, g_consumer, CTLFLAG_RD,
           SYSCTL_NULL_INT_PTR, sizeof(struct g_consumer), "sizeof(struct g_consumer)");
   SYSCTL_INT(_debug_sizeof, OID_AUTO, g_bioq, CTLFLAG_RD,
           SYSCTL_NULL_INT_PTR, sizeof(struct g_bioq), "sizeof(struct g_bioq)");

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