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* mdmon - monitor external metadata arrays
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* Copyright (C) 2007-2009 Neil Brown <neilb@suse.de>
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* Copyright (C) 2007-2009 Intel Corporation
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
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#include <sys/syscall.h>
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#include <sys/select.h>
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static char *array_states[] = {
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"clear", "inactive", "suspended", "readonly", "read-auto",
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"clean", "active", "write-pending", "active-idle", NULL };
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static char *sync_actions[] = {
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"idle", "reshape", "resync", "recover", "check", "repair", NULL
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static int write_attr(char *attr, int fd)
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return write(fd, attr, strlen(attr));
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static void add_fd(fd_set *fds, int *maxfd, int fd)
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static int read_attr(char *buf, int len, int fd)
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n = read(fd, buf, len - 1);
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static unsigned long long read_resync_start(int fd)
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n = read_attr(buf, 30, fd);
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if (strncmp(buf, "none", 4) == 0)
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return strtoull(buf, NULL, 10);
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static unsigned long long read_sync_completed(int fd)
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unsigned long long val;
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n = read_attr(buf, 50, fd);
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val = strtoull(buf, &ep, 0);
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if (ep == buf || (*ep != 0 && *ep != '\n' && *ep != ' '))
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static enum array_state read_state(int fd)
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int n = read_attr(buf, 20, fd);
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return (enum array_state) sysfs_match_word(buf, array_states);
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static enum sync_action read_action( int fd)
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int n = read_attr(buf, 20, fd);
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return (enum sync_action) sysfs_match_word(buf, sync_actions);
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int read_dev_state(int fd)
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int n = read_attr(buf, 60, fd);
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if (sysfs_attr_match(cp, "faulty"))
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if (sysfs_attr_match(cp, "in_sync"))
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if (sysfs_attr_match(cp, "write_mostly"))
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rv |= DS_WRITE_MOSTLY;
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if (sysfs_attr_match(cp, "spare"))
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if (sysfs_attr_match(cp, "blocked"))
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cp = strchr(cp, ',');
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static void signal_manager(void)
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/* tgkill(getpid(), mon_tid, SIGUSR1); */
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syscall(SYS_tgkill, pid, mgr_tid, SIGUSR1);
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/* Monitor a set of active md arrays - all of which share the
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* same metadata - and respond to events that require
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* New arrays are detected by another thread which allocates
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* required memory and attaches the data structure to our list.
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* This is detected by array_state going to 'clear' or 'inactive'.
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* while we thought it was active.
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* Response is to mark metadata as clean and 'clear' the array(??)
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* array_state if 'write-pending'
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* We mark metadata as 'dirty' then set array to 'active'.
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* Either ignore, or mark clean, then mark metadata as clean.
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* detected by rd-N/state reporting "faulty"
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* mark device as 'failed' in metadata, let the kernel release the
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* device by writing '-blocked' to rd/state, and finally write 'remove' to
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* rd/state. Before a disk can be replaced it must be failed and removed
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* from all container members, this will be preemptive for the other
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* sync_action was 'resync' and becomes 'idle' and resync_start becomes
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* Notify metadata that sync is complete.
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* sync_action changes from 'recover' to 'idle'
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* Check each device state and mark metadata if 'faulty' or 'in_sync'.
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* This only happens on finding a new array... mdadm will have set
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* 'resync_start' to the correct value. If 'resync_start' indicates that an
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* resync needs to occur set the array to the 'active' state rather than the
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* initial read-auto state.
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* We wait for a change (poll/select) on array_state, sync_action, and
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* each rd-X/state file.
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* When we get any change, we check everything. So read each state file,
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* then decide what to do.
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* The core action is to write new metadata to all devices in the array.
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* This is done at most once on any wakeup.
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* After that we might:
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* - update the array_state
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* - set the role of some devices.
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* - request a sync_action
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static int read_and_act(struct active_array *a)
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unsigned long long sync_completed;
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int check_degraded = 0;
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a->next_state = bad_word;
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a->next_action = bad_action;
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a->curr_state = read_state(a->info.state_fd);
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a->curr_action = read_action(a->action_fd);
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a->info.resync_start = read_resync_start(a->resync_start_fd);
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sync_completed = read_sync_completed(a->sync_completed_fd);
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for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
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if (mdi->state_fd >= 0) {
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mdi->recovery_start = read_resync_start(mdi->recovery_fd);
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mdi->curr_state = read_dev_state(mdi->state_fd);
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if (a->curr_state <= inactive &&
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a->prev_state > inactive) {
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/* array has been stopped */
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a->container->ss->set_array_state(a, 1);
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a->next_state = clear;
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if (a->curr_state == write_pending) {
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a->container->ss->set_array_state(a, 0);
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a->next_state = active;
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if (a->curr_state == active_idle) {
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/* Set array to 'clean' FIRST, then mark clean
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a->next_state = clean;
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if (a->curr_state == clean) {
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a->container->ss->set_array_state(a, 1);
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if (a->curr_state == active ||
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a->curr_state == suspended ||
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a->curr_state == bad_word)
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if (a->curr_state == readonly) {
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/* Well, I'm ready to handle things. If readonly
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* wasn't requested, transition to read-auto.
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read_attr(buf, sizeof(buf), a->metadata_fd);
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if (strncmp(buf, "external:-", 10) == 0) {
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/* explicit request for readonly array. Leave it alone */
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if (a->container->ss->set_array_state(a, 2))
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a->next_state = read_auto; /* array is clean */
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a->next_state = active; /* Now active for recovery etc */
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a->curr_action == idle &&
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a->prev_action == resync) {
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/* A resync has finished. The endpoint is recorded in
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* 'sync_start'. We don't update the metadata
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* until the array goes inactive or readonly though.
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* Just check if we need to fiddle spares.
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a->container->ss->set_array_state(a, a->curr_state <= clean);
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a->curr_action == idle &&
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a->prev_action == recover) {
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/* A recovery has finished. Some disks may be in sync now,
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* and the array may no longer be degraded
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for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
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a->container->ss->set_disk(a, mdi->disk.raid_disk,
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if (! (mdi->curr_state & DS_INSYNC))
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/* Check for failures and if found:
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* 1/ Record the failure in the metadata and unblock the device.
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* FIXME update the kernel to stop notifying on failed drives when
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* the array is readonly and we have cleared 'blocked'
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* 2/ Try to remove the device if the array is writable, or can be
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for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
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if (mdi->curr_state & DS_FAULTY) {
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a->container->ss->set_disk(a, mdi->disk.raid_disk,
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mdi->next_state |= DS_UNBLOCK;
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if (a->curr_state == read_auto) {
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a->container->ss->set_array_state(a, 0);
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a->next_state = active;
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if (a->curr_state > readonly)
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mdi->next_state |= DS_REMOVE;
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/* Check for recovery checkpoint notifications. We need to be a
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* minimum distance away from the last checkpoint to prevent
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* over checkpointing. Note reshape checkpointing is not
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if (sync_completed > a->last_checkpoint &&
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sync_completed - a->last_checkpoint > a->info.component_size >> 4 &&
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a->curr_action > reshape) {
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/* A (non-reshape) sync_action has reached a checkpoint.
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* Record the updated position in the metadata
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a->last_checkpoint = sync_completed;
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a->container->ss->set_array_state(a, a->curr_state <= clean);
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} else if (sync_completed > a->last_checkpoint)
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a->last_checkpoint = sync_completed;
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a->container->ss->sync_metadata(a->container);
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dprintf("%s(%d): state:%s action:%s next(", __func__, a->info.container_member,
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array_states[a->curr_state], sync_actions[a->curr_action]);
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/* Effect state changes in the array */
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if (a->next_state != bad_word) {
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dprintf(" state:%s", array_states[a->next_state]);
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write_attr(array_states[a->next_state], a->info.state_fd);
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if (a->next_action != bad_action) {
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write_attr(sync_actions[a->next_action], a->action_fd);
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dprintf(" action:%s", sync_actions[a->next_action]);
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for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
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if (mdi->next_state & DS_UNBLOCK) {
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dprintf(" %d:-blocked", mdi->disk.raid_disk);
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write_attr("-blocked", mdi->state_fd);
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if ((mdi->next_state & DS_REMOVE) && mdi->state_fd >= 0) {
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/* the kernel may not be able to immediately remove the
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* disk, we can simply wait until the next event to try
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remove_result = write_attr("remove", mdi->state_fd);
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if (remove_result > 0) {
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dprintf(" %d:removed", mdi->disk.raid_disk);
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close(mdi->state_fd);
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if (mdi->next_state & DS_INSYNC) {
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write_attr("+in_sync", mdi->state_fd);
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dprintf(" %d:+in_sync", mdi->disk.raid_disk);
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/* move curr_ to prev_ */
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a->prev_state = a->curr_state;
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a->prev_action = a->curr_action;
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for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
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mdi->prev_state = mdi->curr_state;
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if (check_degraded) {
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/* manager will do the actual check */
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a->check_degraded = 1;
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static struct mdinfo *
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find_device(struct active_array *a, int major, int minor)
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for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
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if (mdi->disk.major == major && mdi->disk.minor == minor)
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static void reconcile_failed(struct active_array *aa, struct mdinfo *failed)
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struct active_array *a;
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struct mdinfo *victim;
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for (a = aa; a; a = a->next) {
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victim = find_device(a, failed->disk.major, failed->disk.minor);
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if (!(victim->curr_state & DS_FAULTY))
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write_attr("faulty", victim->state_fd);
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static void dprint_wake_reasons(fd_set *fds)
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fprintf(stderr, "monitor: wake ( ");
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for (i = 0; i < FD_SETSIZE; i++) {
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if (FD_ISSET(i, fds)) {
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sprintf(proc_path, "/proc/%d/fd/%d",
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rv = readlink(proc_path, link, sizeof(link) - 1);
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fprintf(stderr, "%d:unknown ", i);
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basename = strrchr(link, '/');
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fprintf(stderr, "%d:%s ",
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i, basename ? ++basename : link);
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fprintf(stderr, ")\n");
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int monitor_loop_cnt;
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static int wait_and_act(struct supertype *container, int nowait)
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struct active_array **aap = &container->arrays;
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struct active_array *a, **ap;
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static unsigned int dirty_arrays = ~0; /* start at some non-zero value */
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for (ap = aap ; *ap ;) {
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/* once an array has been deactivated we want to
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* ask the manager to discard it.
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add_fd(&rfds, &maxfd, a->info.state_fd);
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add_fd(&rfds, &maxfd, a->action_fd);
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add_fd(&rfds, &maxfd, a->sync_completed_fd);
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for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
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add_fd(&rfds, &maxfd, mdi->state_fd);
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if (manager_ready && (*aap == NULL || (sigterm && !dirty_arrays))) {
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/* No interesting arrays, or we have been told to
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* terminate and everything is clean. Lets see about
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* exiting. Note that blocking at this point is not a
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* problem as there are no active arrays, there is
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* nothing that we need to be ready to do.
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int fd = open_dev_excl(container->devnum);
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if (fd >= 0 || errno != EBUSY) {
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/* OK, we are safe to leave */
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if (sigterm && !dirty_arrays)
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dprintf("caught sigterm, all clean... exiting\n");
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dprintf("no arrays to monitor... exiting\n");
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/* On SIGTERM, someone (the take-over mdmon) will
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remove_pidfile(container->devname);
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sigprocmask(SIG_UNBLOCK, NULL, &set);
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sigdelset(&set, SIGUSR1);
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monitor_loop_cnt |= 1;
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rv = pselect(maxfd+1, NULL, NULL, &rfds, NULL, &set);
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monitor_loop_cnt += 1;
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if (rv == -1 && errno == EINTR)
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dprint_wake_reasons(&rfds);
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struct metadata_update *this;
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for (this = update_queue; this ; this = this->next)
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container->ss->process_update(container, this);
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update_queue_handled = update_queue;
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container->ss->sync_metadata(container);
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for (a = *aap; a ; a = a->next) {
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if (a->replaces && !discard_this) {
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struct active_array **ap;
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for (ap = &a->next; *ap && *ap != a->replaces;
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discard_this = a->replaces;
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/* FIXME check if device->state_fd need to be cleared?*/
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is_dirty = read_and_act(a);
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dirty_arrays += is_dirty;
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/* when terminating stop manipulating the array after it
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* is clean, but make sure read_and_act() is given a
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* chance to handle 'active_idle'
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if (sigterm && !is_dirty)
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a->container = NULL; /* stop touching this array */
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/* propagate failures across container members */
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for (a = *aap; a ; a = a->next) {
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for (mdi = a->info.devs ; mdi ; mdi = mdi->next)
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if (mdi->curr_state & DS_FAULTY)
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reconcile_failed(*aap, mdi);
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void do_monitor(struct supertype *container)
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rv = wait_and_act(container, first);
added
removed
monitor.c
