Having single function to read mdmon pid file.

[thirdparty/mdadm.git] / monitor.c

/*
 * mdmon - monitor external metadata arrays
 *
 * Copyright (C) 2007-2009 Neil Brown <neilb@suse.de>
 * Copyright (C) 2007-2009 Intel Corporation
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "mdadm.h"
#include "mdmon.h"
#include <sys/syscall.h>
#include <sys/select.h>
#include <signal.h>

static char *array_states[] = {
        "clear", "inactive", "suspended", "readonly", "read-auto",
        "clean", "active", "write-pending", "active-idle", NULL };
static char *sync_actions[] = {
        "idle", "reshape", "resync", "recover", "check", "repair", NULL
};

static int write_attr(char *attr, int fd)
{
        return write(fd, attr, strlen(attr));
}

static void add_fd(fd_set *fds, int *maxfd, int fd)
{
        if (fd < 0)
                return;
        if (fd > *maxfd)
                *maxfd = fd;
        FD_SET(fd, fds);
}

static int read_attr(char *buf, int len, int fd)
{
        int n;

        if (fd < 0) {
                buf[0] = 0;
                return 0;
        }
        lseek(fd, 0, 0);
        n = read(fd, buf, len - 1);

        if (n <= 0) {
                buf[0] = 0;
                return 0;
        }
        buf[n] = 0;
        if (buf[n-1] == '\n')
                buf[n-1] = 0;
        return n;
}

static unsigned long long read_resync_start(int fd)
{
        char buf[30];
        int n;

        n = read_attr(buf, 30, fd);
        if (n <= 0)
                return 0;
        if (strncmp(buf, "none", 4) == 0)
                return MaxSector;
        else
                return strtoull(buf, NULL, 10);
}

static enum array_state read_state(int fd)
{
        char buf[20];
        int n = read_attr(buf, 20, fd);

        if (n <= 0)
                return bad_word;
        return (enum array_state) sysfs_match_word(buf, array_states);
}

static enum sync_action read_action( int fd)
{
        char buf[20];
        int n = read_attr(buf, 20, fd);

        if (n <= 0)
                return bad_action;
        return (enum sync_action) sysfs_match_word(buf, sync_actions);
}

int read_dev_state(int fd)
{
        char buf[60];
        int n = read_attr(buf, 60, fd);
        char *cp;
        int rv = 0;

        if (n <= 0)
                return 0;

        cp = buf;
        while (cp) {
                if (sysfs_attr_match(cp, "faulty"))
                        rv |= DS_FAULTY;
                if (sysfs_attr_match(cp, "in_sync"))
                        rv |= DS_INSYNC;
                if (sysfs_attr_match(cp, "write_mostly"))
                        rv |= DS_WRITE_MOSTLY;
                if (sysfs_attr_match(cp, "spare"))
                        rv |= DS_SPARE;
                if (sysfs_attr_match(cp, "blocked"))
                        rv |= DS_BLOCKED;
                cp = strchr(cp, ',');
                if (cp)
                        cp++;
        }
        return rv;
}

static void signal_manager(void)
{
        /* tgkill(getpid(), mon_tid, SIGUSR1); */
        int pid = getpid();
        syscall(SYS_tgkill, pid, mgr_tid, SIGUSR1);
}

/* Monitor a set of active md arrays - all of which share the
 * same metadata - and respond to events that require
 * metadata update.
 *
 * New arrays are detected by another thread which allocates
 * required memory and attaches the data structure to our list.
 *
 * Events:
 *  Array stops.
 *    This is detected by array_state going to 'clear' or 'inactive'.
 *    while we thought it was active.
 *    Response is to mark metadata as clean and 'clear' the array(??)
 *  write-pending
 *    array_state if 'write-pending'
 *    We mark metadata as 'dirty' then set array to 'active'.
 *  active_idle
 *    Either ignore, or mark clean, then mark metadata as clean.
 *
 *  device fails
 *    detected by rd-N/state reporting "faulty"
 *    mark device as 'failed' in metadata, let the kernel release the
 *    device by writing '-blocked' to rd/state, and finally write 'remove' to
 *    rd/state.  Before a disk can be replaced it must be failed and removed
 *    from all container members, this will be preemptive for the other
 *    arrays... safe?
 *
 *  sync completes
 *    sync_action was 'resync' and becomes 'idle' and resync_start becomes
 *    MaxSector
 *    Notify metadata that sync is complete.
 *
 *  recovery completes
 *    sync_action changes from 'recover' to 'idle'
 *    Check each device state and mark metadata if 'faulty' or 'in_sync'.
 *
 *  deal with resync
 *    This only happens on finding a new array... mdadm will have set
 *    'resync_start' to the correct value.  If 'resync_start' indicates that an
 *    resync needs to occur set the array to the 'active' state rather than the
 *    initial read-auto state.
 *
 *
 *
 * We wait for a change (poll/select) on array_state, sync_action, and
 * each rd-X/state file.
 * When we get any change, we check everything.  So read each state file,
 * then decide what to do.
 *
 * The core action is to write new metadata to all devices in the array.
 * This is done at most once on any wakeup.
 * After that we might:
 *   - update the array_state
 *   - set the role of some devices.
 *   - request a sync_action
 *
 */

static int read_and_act(struct active_array *a)
{
        int check_degraded = 0;
        int deactivate = 0;
        struct mdinfo *mdi;
        int dirty = 0;

        a->next_state = bad_word;
        a->next_action = bad_action;

        a->curr_state = read_state(a->info.state_fd);
        a->curr_action = read_action(a->action_fd);
        a->info.resync_start = read_resync_start(a->resync_start_fd);
        for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
                mdi->next_state = 0;
                if (mdi->state_fd >= 0) {
                        mdi->recovery_start = read_resync_start(mdi->recovery_fd);
                        mdi->curr_state = read_dev_state(mdi->state_fd);
                }
        }

        if (a->curr_state <= inactive &&
            a->prev_state > inactive) {
                /* array has been stopped */
                a->container->ss->set_array_state(a, 1);
                a->next_state = clear;
                deactivate = 1;
        }
        if (a->curr_state == write_pending) {
                a->container->ss->set_array_state(a, 0);
                a->next_state = active;
                dirty = 1;
        }
        if (a->curr_state == active_idle) {
                /* Set array to 'clean' FIRST, then mark clean
                 * in the metadata
                 */
                a->next_state = clean;
                dirty = 1;
        }
        if (a->curr_state == clean) {
                a->container->ss->set_array_state(a, 1);
        }
        if (a->curr_state == active ||
            a->curr_state == suspended ||
            a->curr_state == bad_word)
                dirty = 1;
        if (a->curr_state == readonly) {
                /* Well, I'm ready to handle things.  If readonly
                 * wasn't requested, transition to read-auto.
                 */
                char buf[64];
                read_attr(buf, sizeof(buf), a->metadata_fd);
                if (strncmp(buf, "external:-", 10) == 0) {
                        /* explicit request for readonly array.  Leave it alone */
                        ;
                } else {
                        if (a->container->ss->set_array_state(a, 2))
                                a->next_state = read_auto; /* array is clean */
                        else {
                                a->next_state = active; /* Now active for recovery etc */
                                dirty = 1;
                        }
                }
        }

        if (!deactivate &&
            a->curr_action == idle &&
            a->prev_action == resync) {
                /* A resync has finished.  The endpoint is recorded in
                 * 'sync_start'.  We don't update the metadata
                 * until the array goes inactive or readonly though.
                 * Just check if we need to fiddle spares.
                 */
                a->container->ss->set_array_state(a, a->curr_state <= clean);
                check_degraded = 1;
        }

        if (!deactivate &&
            a->curr_action == idle &&
            a->prev_action == recover) {
                /* A recovery has finished.  Some disks may be in sync now,
                 * and the array may no longer be degraded
                 */
                for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
                        a->container->ss->set_disk(a, mdi->disk.raid_disk,
                                                   mdi->curr_state);
                        if (! (mdi->curr_state & DS_INSYNC))
                                check_degraded = 1;
                }
        }

        /* Check for failures and if found:
         * 1/ Record the failure in the metadata and unblock the device.
         *    FIXME update the kernel to stop notifying on failed drives when
         *    the array is readonly and we have cleared 'blocked'
         * 2/ Try to remove the device if the array is writable, or can be
         *    made writable.
         */
        for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
                if (mdi->curr_state & DS_FAULTY) {
                        a->container->ss->set_disk(a, mdi->disk.raid_disk,
                                                   mdi->curr_state);
                        check_degraded = 1;
                        mdi->next_state |= DS_UNBLOCK;
                        if (a->curr_state == read_auto) {
                                a->container->ss->set_array_state(a, 0);
                                a->next_state = active;
                        }
                        if (a->curr_state > readonly)
                                mdi->next_state |= DS_REMOVE;
                }
        }

        a->container->ss->sync_metadata(a->container);
        dprintf("%s(%d): state:%s action:%s next(", __func__, a->info.container_member,
                array_states[a->curr_state], sync_actions[a->curr_action]);

        /* Effect state changes in the array */
        if (a->next_state != bad_word) {
                dprintf(" state:%s", array_states[a->next_state]);
                write_attr(array_states[a->next_state], a->info.state_fd);
        }
        if (a->next_action != bad_action) {
                write_attr(sync_actions[a->next_action], a->action_fd);
                dprintf(" action:%s", sync_actions[a->next_action]);
        }
        for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
                if (mdi->next_state & DS_UNBLOCK) {
                        dprintf(" %d:-blocked", mdi->disk.raid_disk);
                        write_attr("-blocked", mdi->state_fd);
                }

                if ((mdi->next_state & DS_REMOVE) && mdi->state_fd >= 0) {
                        int remove_result;

                        /* the kernel may not be able to immediately remove the
                         * disk, we can simply wait until the next event to try
                         * again.
                         */
                        remove_result = write_attr("remove", mdi->state_fd);
                        if (remove_result > 0) {
                                dprintf(" %d:removed", mdi->disk.raid_disk);
                                close(mdi->state_fd);
                                mdi->state_fd = -1;
                        }
                }
                if (mdi->next_state & DS_INSYNC) {
                        write_attr("+in_sync", mdi->state_fd);
                        dprintf(" %d:+in_sync", mdi->disk.raid_disk);
                }
        }
        dprintf(" )\n");

        /* move curr_ to prev_ */
        a->prev_state = a->curr_state;

        a->prev_action = a->curr_action;

        for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
                mdi->prev_state = mdi->curr_state;
                mdi->next_state = 0;
        }

        if (check_degraded) {
                /* manager will do the actual check */
                a->check_degraded = 1;
                signal_manager();
        }

        if (deactivate)
                a->container = NULL;

        return dirty;
}

static struct mdinfo *
find_device(struct active_array *a, int major, int minor)
{
        struct mdinfo *mdi;

        for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
                if (mdi->disk.major == major && mdi->disk.minor == minor)
                        return mdi;

        return NULL;
}

static void reconcile_failed(struct active_array *aa, struct mdinfo *failed)
{
        struct active_array *a;
        struct mdinfo *victim;

        for (a = aa; a; a = a->next) {
                if (!a->container)
                        continue;
                victim = find_device(a, failed->disk.major, failed->disk.minor);
                if (!victim)
                        continue;

                if (!(victim->curr_state & DS_FAULTY))
                        write_attr("faulty", victim->state_fd);
        }
}

#ifdef DEBUG
static void dprint_wake_reasons(fd_set *fds)
{
        int i;
        char proc_path[256];
        char link[256];
        char *basename;
        int rv;

        fprintf(stderr, "monitor: wake ( ");
        for (i = 0; i < FD_SETSIZE; i++) {
                if (FD_ISSET(i, fds)) {
                        sprintf(proc_path, "/proc/%d/fd/%d",
                                (int) getpid(), i);

                        rv = readlink(proc_path, link, sizeof(link) - 1);
                        if (rv < 0) {
                                fprintf(stderr, "%d:unknown ", i);
                                continue;
                        }
                        link[rv] = '\0';
                        basename = strrchr(link, '/');
                        fprintf(stderr, "%d:%s ",
                                i, basename ? ++basename : link);
                }
        }
        fprintf(stderr, ")\n");
}
#endif

int monitor_loop_cnt;

static int wait_and_act(struct supertype *container, int nowait)
{
        fd_set rfds;
        int maxfd = 0;
        struct active_array **aap = &container->arrays;
        struct active_array *a, **ap;
        int rv;
        struct mdinfo *mdi;
        static unsigned int dirty_arrays = ~0; /* start at some non-zero value */

        FD_ZERO(&rfds);

        for (ap = aap ; *ap ;) {
                a = *ap;
                /* once an array has been deactivated we want to
                 * ask the manager to discard it.
                 */
                if (!a->container) {
                        if (discard_this) {
                                ap = &(*ap)->next;
                                continue;
                        }
                        *ap = a->next;
                        a->next = NULL;
                        discard_this = a;
                        signal_manager();
                        continue;
                }

                add_fd(&rfds, &maxfd, a->info.state_fd);
                add_fd(&rfds, &maxfd, a->action_fd);
                for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
                        add_fd(&rfds, &maxfd, mdi->state_fd);

                ap = &(*ap)->next;
        }

        if (manager_ready && (*aap == NULL || (sigterm && !dirty_arrays))) {
                /* No interesting arrays, or we have been told to
                 * terminate and everything is clean.  Lets see about
                 * exiting.  Note that blocking at this point is not a
                 * problem as there are no active arrays, there is
                 * nothing that we need to be ready to do.
                 */
                int fd = open_dev_excl(container->devnum);
                if (fd >= 0 || errno != EBUSY) {
                        /* OK, we are safe to leave */
                        if (sigterm && !dirty_arrays)
                                dprintf("caught sigterm, all clean... exiting\n");
                        else
                                dprintf("no arrays to monitor... exiting\n");
                        remove_pidfile(container->devname);
                        exit_now = 1;
                        signal_manager();
                        exit(0);
                }
        }

        if (!nowait) {
                sigset_t set;
                sigprocmask(SIG_UNBLOCK, NULL, &set);
                sigdelset(&set, SIGUSR1);
                monitor_loop_cnt |= 1;
                rv = pselect(maxfd+1, NULL, NULL, &rfds, NULL, &set);
                monitor_loop_cnt += 1;
                if (rv == -1 && errno == EINTR)
                        rv = 0;
                #ifdef DEBUG
                dprint_wake_reasons(&rfds);
                #endif

        }

        if (update_queue) {
                struct metadata_update *this;

                for (this = update_queue; this ; this = this->next)
                        container->ss->process_update(container, this);

                update_queue_handled = update_queue;
                update_queue = NULL;
                signal_manager();
                container->ss->sync_metadata(container);
        }

        rv = 0;
        dirty_arrays = 0;
        for (a = *aap; a ; a = a->next) {
                int is_dirty;

                if (a->replaces && !discard_this) {
                        struct active_array **ap;
                        for (ap = &a->next; *ap && *ap != a->replaces;
                             ap = & (*ap)->next)
                                ;
                        if (*ap)
                                *ap = (*ap)->next;
                        discard_this = a->replaces;
                        a->replaces = NULL;
                        /* FIXME check if device->state_fd need to be cleared?*/
                        signal_manager();
                }
                if (a->container) {
                        is_dirty = read_and_act(a);
                        rv |= 1;
                        dirty_arrays += is_dirty;
                        /* when terminating stop manipulating the array after it
                         * is clean, but make sure read_and_act() is given a
                         * chance to handle 'active_idle'
                         */
                        if (sigterm && !is_dirty)
                                a->container = NULL; /* stop touching this array */
                }
        }

        /* propagate failures across container members */
        for (a = *aap; a ; a = a->next) {
                if (!a->container)
                        continue;
                for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
                        if (mdi->curr_state & DS_FAULTY)
                                reconcile_failed(*aap, mdi);
        }

        return rv;
}

void do_monitor(struct supertype *container)
{
        int rv;
        int first = 1;
        do {
                rv = wait_and_act(container, first);
                first = 0;
        } while (rv >= 0);
}