1 files changed, 578 insertions, 0 deletions

diff --git a/monitor.c b/monitor.c
new file mode 100644
index 0000000..5c17910
--- /dev/null
+++ b/monitor.c
@@ -0,0 +1,578 @@
+/*
+ * mdmon - monitor external metadata arrays
+ *
+ * Copyright (C) 2007-2008 Neil Brown <neilb@suse.de>
+ * Copyright (C) 2007-2008 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;
+}
+
+int get_resync_start(struct active_array *a)
+{
+	char buf[30];
+	int n;
+
+	n = read_attr(buf, 30, a->resync_start_fd);
+	if (n <= 0)
+		return n;
+
+	a->resync_start = strtoull(buf, NULL, 10);
+
+	return 1;
+}
+
+
+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;
+
+	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);
+	for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
+		mdi->next_state = 0;
+		if (mdi->state_fd >= 0)
+			mdi->curr_state = read_dev_state(mdi->state_fd);
+	}
+
+	if (a->curr_state <= inactive &&
+	    a->prev_state > inactive) {
+		/* array has been stopped */
+		get_resync_start(a);
+		a->container->ss->set_array_state(a, 1);
+		a->next_state = clear;
+		deactivate = 1;
+	}
+	if (a->curr_state == write_pending) {
+		get_resync_start(a);
+		a->container->ss->set_array_state(a, 0);
+		a->next_state = active;
+	}
+	if (a->curr_state == active_idle) {
+		/* Set array to 'clean' FIRST, then mark clean
+		 * in the metadata
+		 */
+		a->next_state = clean;
+	}
+	if (a->curr_state == clean) {
+		get_resync_start(a);
+		a->container->ss->set_array_state(a, 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 {
+			get_resync_start(a);
+			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 */
+		}
+	}
+
+	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.
+		 */
+		get_resync_start(a);
+		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 1;
+}
+
+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, &rfds, NULL, NULL, 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)
+			rv += read_and_act(a);
+		else
+			continue;
+
+		/* when terminating stop manipulating the array after it is
+		 * clean, but make sure read_and_act() is given a chance to
+		 * handle 'active_idle'
+		 */
+		switch (read_state(a->info.state_fd)) {
+			case active:
+			case active_idle:
+			case suspended:
+			case bad_word:
+				is_dirty = 1;
+				break;
+			default:
+				if (a->curr_state == active_idle)
+					is_dirty = 1;
+				else
+					is_dirty = 0;
+				break;
+		}
+		dirty_arrays += is_dirty;
+		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);
+}