Merge mdmon

1 files changed, 372 insertions, 0 deletions

diff --git a/monitor.c b/monitor.c
new file mode 100644
index 0000000..38725d1
--- /dev/null
+++ b/monitor.c
@@ -0,0 +1,372 @@
+
+#include "mdadm.h"
+#include "mdmon.h"
+
+#include <sys/select.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 int get_sync_pos(struct active_array *a)
+{
+	char buf[30];
+	int n;
+
+	n = read_attr(buf, 30, a->sync_pos_fd);
+	if (n <= 0)
+		return n;
+
+	if (strncmp(buf, "max", 3) == 0) {
+		a->sync_pos = ~(unsigned long long)0;
+		return 1;
+	}
+	a->sync_pos = strtoull(buf, NULL, 10);
+	return 1;
+}
+
+
+static int attr_match(const char *attr, const char *str)
+{
+	/* See if attr, read from a sysfs file, matches
+	 * str.  They must either be the same, or attr can
+	 * have a trailing newline or comma
+	 */
+	while (*attr && *str && *attr == *str) {
+		attr++;
+		str++;
+	}
+
+	if (*str || (*attr && *attr != ',' && *attr != '\n'))
+		return 0;
+	return 1;
+}
+
+static int match_word(const char *word, char **list)
+{
+	int n;
+	for (n=0; list[n]; n++)
+		if (attr_match(word, list[n]))
+			break;
+	return n;
+}
+
+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) 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) match_word(buf, sync_actions);
+}
+
+#define DS_FAULTY	1
+#define	DS_INSYNC	2
+#define	DS_WRITE_MOSTLY	4
+#define	DS_SPARE	8
+#define	DS_REMOVE	1024
+
+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 (attr_match("faulty", cp))
+			rv |= DS_FAULTY;
+		if (attr_match("in_sync", cp))
+			rv |= DS_INSYNC;
+		if (attr_match("write_mostly", cp))
+			rv |= DS_WRITE_MOSTLY;
+		if (attr_match("spare", cp))
+			rv |= DS_SPARE;
+		cp = strchr(cp, ',');
+		if (cp)
+			cp++;
+	}
+	return rv;
+}
+
+
+/* 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, the remove device
+ *    by writing 'remove' to rd/state.
+ *
+ *  sync completes
+ *    sync_action was 'resync' and becomes 'idle' and resync_start becomes
+ *    MaxSector
+ *    Notify metadata that sync is complete.
+ *    "Deal with Degraded"
+ *
+ *  recovery completes
+ *    sync_action changes from 'recover' to 'idle'
+ *    Check each device state and mark metadata if 'faulty' or 'in_sync'.
+ *    "Deal with Degraded"
+ *
+ *  deal with degraded array
+ *    We only do this when first noticing the array is degraded.
+ *    This can be when we first see the array, when sync completes or
+ *    when recovery completes.
+ *
+ *    Check if number of failed devices suggests recovery is needed, and
+ *    skip if not.
+ *    Ask metadata for a spare device
+ *    Add device as not in_sync and give a role
+ *    Update metadata.
+ *    Start recovery.
+ *
+ *  deal with resync
+ *    This only happens on finding a new array....
+ *      Maybe this is done by mdadm before passing the array to us?
+ *
+ *    If array is 'clean' but metadata is 'dirty', start a resync
+ *    and mark array as 'dirty'.
+ *
+ *
+ *
+ *
+ * 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;
+	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;
+		mdi->curr_state = read_dev_state(mdi->state_fd);
+	}
+
+	if (a->curr_state <= inactive &&
+	    a->prev_state > inactive) {
+		/* array has been stopped */
+		get_sync_pos(a);
+		a->container->ss->mark_clean(a, a->sync_pos);
+		a->next_state = clear;
+	}
+	if (a->curr_state == write_pending) {
+		a->container->ss->mark_dirty(a);
+		a->next_state = active;
+	}
+	if (a->curr_state == active_idle) {
+		/* Set array to 'clean' FIRST, then
+		 * a->ss->mark_clean(a);
+		 * just ignore for now.
+		 */
+	}
+
+	if (a->curr_state == readonly) {
+		/* Well, I'm ready to handle things, so
+		 * read-auto is OK. FIXME what if we really want
+		 * readonly ???
+		 */
+		a->next_state = read_auto;
+	}
+
+	if (a->curr_action == idle &&
+	    a->prev_action == resync) {
+		/* check resync_start to see if it is 'max'.
+		 * Do I open here, or have it open the whole time?
+		 */
+		get_sync_pos(a);
+		check_degraded = 1;
+	}
+
+	if (a->curr_action == idle &&
+	    a->prev_action == recover) {
+		for (mdi = a->info.devs ; mdi ; mdi = mdi->next) {
+			a->container->ss->set_disk(a, mdi->disk.raid_disk);
+			if (! (mdi->curr_state & DS_INSYNC))
+				check_degraded = 1;
+		}
+	}
+
+
+	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);
+			check_degraded = 1;
+			mdi->next_state = DS_REMOVE;
+		}
+	}
+
+	if (check_degraded) {
+		// FIXME;
+	}
+
+	a->container->ss->sync_metadata(a);
+
+	/* Effect state changes in the array */
+	if (a->next_state != bad_word)
+		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);
+	for (mdi = a->info.devs; mdi ; mdi = mdi->next) {
+		if (mdi->next_state == DS_REMOVE)
+			write_attr("remove", mdi->state_fd);
+		if (mdi->next_state & DS_INSYNC)
+			write_attr("+in_sync", mdi->state_fd);
+	}
+
+	/* 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;
+	}
+
+	return 1;
+}
+
+static int wait_and_act(struct active_array *aa, int pfd, int nowait)
+{
+	fd_set rfds;
+	int maxfd = 0;
+	struct active_array *a;
+	int rv;
+
+	FD_ZERO(&rfds);
+
+	add_fd(&rfds, &maxfd, pfd);
+	for (a = aa ; a ; a = a->next) {
+		struct mdinfo *mdi;
+
+		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);
+	}
+
+	if (!nowait) {
+		rv = select(maxfd+1, &rfds, NULL, NULL, NULL);
+
+		if (rv <= 0)
+			return rv;
+
+		if (FD_ISSET(pfd, &rfds)) {
+			char buf[4];
+			read(pfd, buf, 4);
+			; // FIXME read from the pipe
+		}
+	}
+
+	for (a = aa; a ; a = a->next) {
+		if (a->replaces) {
+			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;
+		}
+		rv += read_and_act(a);
+	}
+	return rv;
+}
+
+void do_monitor(struct supertype *container)
+{
+	int rv;
+	int first = 1;
+	do {
+		rv = wait_and_act(container->arrays, container->pipe[0], first);
+		first = 0;
+	} while (rv >= 0);
+}