Monitor: policy based spare migration.

[thirdparty/mdadm.git] / policy.c

/*
 * mdadm - manage Linux "md" devices aka RAID arrays.
 *
 * Copyright (C) 2001-2009 Neil Brown <neilb@suse.de>
 *
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *    Author: Neil Brown
 *    Email: <neilb@suse.de>
 */

#include "mdadm.h"
#include <dirent.h>
#include <fnmatch.h>
#include <ctype.h>
#include "dlink.h"
/*
 * Policy module for mdadm.
 * A policy statement about a device lists a set of values for each
 * of a set of names.  Each value can have a metadata type as context.
 *
 * names include:
 *   action - the actions that can be taken on hot-plug
 *   domain - the domain(s) that the device is part of
 *
 * Policy information is extracted from various sources, but
 * particularly from a set of policy rules in mdadm.conf
 */

static void pol_new(struct dev_policy **pol, char *name, char *val, char *metadata)
{
        struct dev_policy *n = malloc(sizeof(*n));
        const char *real_metadata = NULL;
        int i;

        n->name = name;
        n->value = val;

        /* We need to normalise the metadata name */
        if (metadata) {
                for (i = 0; superlist[i] ; i++)
                        if (strcmp(metadata, superlist[i]->name) == 0) {
                                real_metadata = superlist[i]->name;
                                break;
                        }
                if (!real_metadata) {
                        if (strcmp(metadata, "1") == 0 ||
                            strcmp(metadata, "1.0") == 0 ||
                            strcmp(metadata, "1.1") == 0 ||
                            strcmp(metadata, "1.2") == 0)
                                real_metadata = super1.name;
                }
                if (!real_metadata) {
                        static char *prev = NULL;
                        if (prev != metadata) {
                                fprintf(stderr, Name ": metadata=%s unrecognised - ignoring rule\n",
                                        metadata);
                                prev = metadata;
                        }
                        real_metadata = "unknown";
                }
        }

        n->metadata = real_metadata;
        n->next = *pol;
        *pol = n;
}

static int pol_lesseq(struct dev_policy *a, struct dev_policy *b)
{
        int cmp;

        if (a->name < b->name)
                return 1;
        if (a->name > b->name)
                return 0;

        cmp = strcmp(a->value, b->value);
        if (cmp < 0)
                return 1;
        if (cmp > 0)
                return 0;

        return (a->metadata <= b->metadata);
}

static void pol_sort(struct dev_policy **pol)
{
        /* sort policy list in *pol by name/metadata/value
         * using merge sort
         */

        struct dev_policy *pl[2];
        pl[0] = *pol;
        pl[1] = NULL;

        do {
                struct dev_policy **plp[2], *p[2];
                int curr = 0;
                struct dev_policy nul = { NULL, NULL, NULL, NULL };
                struct dev_policy *prev = &nul;
                int next = 0;

                /* p[] are the two lists that we are merging.
                 * plp[] are the ends of the two lists we create
                 * from the merge.
                 * 'curr' is which of plp[] that we are currently
                 *   adding items to.
                 * 'next' is which if p[] we will take the next
                 *   item from.
                 * 'prev' is that last value, which was placed in
                 * plp[curr].
                 */
                plp[0] = &pl[0];
                plp[1] = &pl[1];
                p[0] = pl[0];
                p[1] = pl[1];

                /* take least of p[0] and p[1]
                 * if it is larger than prev, add to
                 * plp[curr], else swap curr then add
                 */
                while (p[0] || p[1]) {
                        if (p[next] == NULL ||
                            (p[1-next] != NULL &&
                             !(pol_lesseq(prev, p[1-next])
                               ^pol_lesseq(prev, p[next])
                               ^pol_lesseq(p[next], p[1-next])))
                                )
                                next = 1 - next;

                        if (!pol_lesseq(prev, p[next]))
                                curr = 1 - curr;

                        *plp[curr] = prev = p[next];
                        plp[curr] = &p[next]->next;
                        p[next] = p[next]->next;
                }
                *plp[0] = NULL;
                *plp[1] = NULL;
        } while (pl[0] && pl[1]);
        if (pl[0])
                *pol = pl[0];
        else
                *pol = pl[1];
}

static void pol_dedup(struct dev_policy *pol)
{
        /* This is a sorted list - remove duplicates. */
        while (pol && pol->next) {
                if (pol_lesseq(pol->next, pol)) {
                        struct dev_policy *tmp = pol->next;
                        pol->next = tmp->next;
                        free(tmp);
                } else
                        pol = pol->next;
        }
}

/*
 * pol_find finds the first entry in the policy
 * list to match name.
 * If it returns non-NULL there is at least one
 * value, but how many can only be found by
 * iterating through the list.
 */
struct dev_policy *pol_find(struct dev_policy *pol, char *name)
{
        while (pol && pol->name < name)
                pol = pol->next;

        if (!pol || pol->name != name)
                return NULL;
        return pol;
}

static char *disk_path(struct mdinfo *disk)
{
        struct stat stb;
        int prefix_len;
        DIR *by_path;
        char symlink[PATH_MAX] = "/dev/disk/by-path/";
        struct dirent *ent;

        by_path = opendir(symlink);
        if (!by_path)
                return NULL;
        prefix_len = strlen(symlink);

        while ((ent = readdir(by_path)) != NULL) {
                if (ent->d_type != DT_LNK)
                        continue;
                strncpy(symlink + prefix_len,
                        ent->d_name,
                        sizeof(symlink) - prefix_len);
                if (stat(symlink, &stb) < 0)
                        continue;
                if ((stb.st_mode & S_IFMT) != S_IFBLK)
                        continue;
                if (stb.st_rdev != makedev(disk->disk.major, disk->disk.minor))
                        continue;
                closedir(by_path);
                return strdup(ent->d_name);
        }
        closedir(by_path);
        return NULL;
}

char type_part[] = "part";
char type_disk[] = "disk";
static char *disk_type(struct mdinfo *disk)
{
        char buf[30+20+20];
        struct stat stb;
        sprintf(buf, "/sys/dev/block/%d:%d/partition",
                disk->disk.major, disk->disk.minor);
        if (stat(buf, &stb) == 0)
                return type_part;
        else
                return type_disk;
}

static int pol_match(struct rule *rule, char *path, char *type)
{
        /* check if this rule matches on path and type */
        int pathok = 0; /* 0 == no path, 1 == match, -1 == no match yet */
        int typeok = 0;

        while (rule) {
                if (rule->name == rule_path) {
                        if (pathok == 0)
                                pathok = -1;
                        if (fnmatch(rule->value, path, 0) == 0)
                                pathok = 1;
                }
                if (rule->name == rule_type) {
                        if (typeok == 0)
                                typeok = -1;
                        if (strcmp(rule->value, type) == 0)
                                typeok = 1;
                }
                rule = rule->next;
        }
        return pathok >= 0 && typeok >= 0;
}

static void pol_merge(struct dev_policy **pol, struct rule *rule)
{
        /* copy any name assignments from rule into pol */
        struct rule *r;
        char *metadata = NULL;
        for (r = rule; r ; r = r->next)
                if (r->name == pol_metadata)
                        metadata = r->value;

        for (r = rule; r ; r = r->next)
                if (r->name == pol_act ||
                    r->name == pol_domain)
                        pol_new(pol, r->name, r->value, metadata);
}

static int path_has_part(char *path, char **part)
{
        /* check if path ends with "-partNN" and
         * if it does, place a pointer to "-pathNN"
         * in 'part'.
         */
        int l = strlen(path);
        while (l > 1 && isdigit(path[l-1]))
                l--;
        if (l < 5 || strncmp(path+l-5, "-part", 5) != 0)
                return 0;
        *part = path+l-4;
        return 1;
}

static void pol_merge_part(struct dev_policy **pol, struct rule *rule, char *part)
{
        /* copy any name assignments from rule into pol, appending
         * -part to any domain.  The string with -part appended is
         * stored with the rule so it has a lifetime to match
         * the rule.
         */
        struct rule *r;
        char *metadata = NULL;
        for (r = rule; r ; r = r->next)
                if (r->name == pol_metadata)
                        metadata = r->value;

        for (r = rule; r ; r = r->next) {
                if (r->name == pol_act)
                        pol_new(pol, r->name, r->value, metadata);
                else if (r->name == pol_domain) {
                        char *dom;
                        int len;
                        if (r->dups == NULL)
                                r->dups = dl_head();
                        len = strlen(r->value);
                        for (dom = dl_next(r->dups); dom != r->dups;
                             dom = dl_next(dom))
                                if (strcmp(dom+len+1, part)== 0)
                                        break;
                        if (dom == r->dups) {
                                char *newdom = dl_strndup(
                                        r->value, len + 1 + strlen(part));
                                strcat(strcat(newdom, "-"), part);
                                dl_add(r->dups, newdom);
                                dom = newdom;
                        }
                        pol_new(pol, r->name, dom, metadata);
                }
        }
}

static struct pol_rule *config_rules = NULL;
static struct pol_rule **config_rules_end = NULL;
static int config_rules_has_path = 0;

/*
 * most policy comes from a set policy rules that are
 * read from the config file.
 * path_policy() gathers policy information for the
 * disk described in the given a 'path' and a 'type'.
 */
struct dev_policy *path_policy(char *path, char *type)
{
        struct pol_rule *rules;
        struct dev_policy *pol = NULL;

        if (!type)
                return NULL;

        rules = config_rules;

        while (rules) {
                char *part;
                if (rules->type == rule_policy)
                        if (pol_match(rules->rule, path, type))
                                pol_merge(&pol, rules->rule);
                if (rules->type == rule_part && strcmp(type, type_part) == 0)
                        if (path_has_part(path, &part)) {
                                *part = 0;
                                if (pol_match(rules->rule, path, type_disk))
                                        pol_merge_part(&pol, rules->rule, part+1);
                                *part = '-';
                        }
                rules = rules->next;
        }
        pol_sort(&pol);
        pol_dedup(pol);
        return pol;
}

void pol_add(struct dev_policy **pol,
                    char *name, char *val,
                    char *metadata)
{
        pol_new(pol, name, val, metadata);
        pol_sort(pol);
        pol_dedup(*pol);
}


/*
 * disk_policy() gathers policy information for the
 * disk described in the given mdinfo (disk.{major,minor}).
 */
struct dev_policy *disk_policy(struct mdinfo *disk)
{
        char *path = NULL;
        char *type = disk_type(disk);
        struct dev_policy *pol = NULL;

        if (!type)
                return NULL;
        if (config_rules_has_path)
                path = disk_path(disk);
        if (!path)
                return NULL;

        pol = path_policy(path, type);

        free(path);
        return pol;
}

struct dev_policy *devnum_policy(int dev)
{
        struct mdinfo disk;
        disk.disk.major = major(dev);
        disk.disk.minor = minor(dev);
        return disk_policy(&disk);
}

/*
 * process policy rules read from config file.
 */

char rule_path[] = "path";
char rule_type[] = "type";

char rule_policy[] = "policy";
char rule_part[] = "part-policy";

char pol_metadata[] = "metadata";
char pol_act[] = "action";
char pol_domain[] = "domain";
char pol_auto[] = "auto";

static int try_rule(char *w, char *name, struct rule **rp)
{
        struct rule *r;
        int len = strlen(name);
        if (strncmp(w, name, len) != 0 ||
            w[len] != '=')
                return 0;
        r = malloc(sizeof(*r));
        r->next = *rp;
        r->name = name;
        r->value = strdup(w+len+1);
        r->dups = NULL;
        *rp = r;
        return 1;
}

void policyline(char *line, char *type)
{
        struct pol_rule *pr;
        char *w;

        if (config_rules_end == NULL)
                config_rules_end = &config_rules;

        pr = malloc(sizeof(*pr));
        pr->type = type;
        pr->rule = NULL;
        for (w = dl_next(line); w != line ; w = dl_next(w)) {
                if (try_rule(w, rule_path, &pr->rule))
                        config_rules_has_path = 1;
                else if (! try_rule(w, rule_type, &pr->rule) &&
                         ! try_rule(w, pol_metadata, &pr->rule) &&
                         ! try_rule(w, pol_act, &pr->rule) &&
                         ! try_rule(w, pol_domain, &pr->rule) &&
                         ! try_rule(w, pol_auto, &pr->rule))
                        fprintf(stderr, Name ": policy rule %s unrecognised and ignored\n",
                                w);
        }
        pr->next = config_rules;
        config_rules = pr;
}

void policy_add(char *type, ...)
{
        va_list ap;
        struct pol_rule *pr;
        char *name, *val;

        pr = malloc(sizeof(*pr));
        pr->type = type;
        pr->rule = NULL;

        va_start(ap, type);
        while ((name = va_arg(ap, char*)) != NULL) {
                struct rule *r;

                val = va_arg(ap, char*);
                r = malloc(sizeof(*r));
                r->next = pr->rule;
                r->name = name;
                r->value = strdup(val);
                r->dups = NULL;
                pr->rule = r;
        }
        pr->next = config_rules;
        config_rules = pr;
}

void policy_free(void)
{
        while (config_rules) {
                struct pol_rule *pr = config_rules;
                struct rule *r;

                config_rules = config_rules->next;

                for (r = pr->rule; r; ) {
                        struct rule *next = r->next;
                        free(r->value);
                        if (r->dups)
                                free_line(r->dups);
                        free(r);
                        r = next;
                }
                free(pr);
        }
        config_rules_end = NULL;
        config_rules_has_path = 0;
}

void dev_policy_free(struct dev_policy *p)
{
        struct dev_policy *t;
        while (p) {
                t = p;
                p = p->next;
                free(t);
        }
}

static enum policy_action map_act(char *act)
{
        if (strcmp(act, "include") == 0)
                return act_include;
        if (strcmp(act, "re-add") == 0)
                return act_re_add;
        if (strcmp(act, "spare") == 0)
                return act_spare;
        if (strcmp(act, "spare-same-slot") == 0)
                return act_spare_same_slot;
        if (strcmp(act, "force-spare") == 0)
                return act_force_spare;
        return act_err;
}

static enum policy_action policy_action(struct dev_policy *plist, const char *metadata)
{
        enum policy_action rv = act_default;
        struct dev_policy *p;

        plist = pol_find(plist, pol_act);
        pol_for_each(p, plist, metadata) {
                enum policy_action a = map_act(p->value);
                if (a > rv)
                        rv = a;
        }
        return rv;
}

int policy_action_allows(struct dev_policy *plist, const char *metadata, enum policy_action want)
{
        enum policy_action act = policy_action(plist, metadata);

        if (act == act_err)
                return 0;
        return (act >= want);
}

int disk_action_allows(struct mdinfo *disk, const char *metadata, enum policy_action want)
{
        struct dev_policy *pol = disk_policy(disk);
        int rv = policy_action_allows(pol, metadata, want);

        dev_policy_free(pol);
        return rv;
}


/* Domain policy:
 * Any device can have a list of domains asserted by different policy
 * statements.
 * An array also has a list of domains comprising all the domains of
 * all the devices in an array.
 * Where an array has a spare-group, that becomes an addition domain for
 * every device in the array and thus for the array.
 *
 * We keep the list of domains in a sorted linked list
 * As dev policies are already sorted, this is fairly easy to manage.
 */

static struct domainlist **domain_merge_one(struct domainlist **domp, char *domain)
{
        /* merge a domain name into a sorted list and return the
         * location of the insertion or match
         */
        struct domainlist *dom = *domp;

        while (dom && strcmp(dom->dom, domain) < 0) {
                domp = &dom->next;
                dom = *domp;
        }
        if (dom == NULL || strcmp(dom->dom, domain) != 0) {
                dom = malloc(sizeof(*dom));
                dom->next = *domp;
                dom->dom = domain;
                *domp = dom;
        }
        return domp;
}

void domain_merge(struct domainlist **domp, struct dev_policy *pollist,
                         const char *metadata)
{
        /* Add to 'domp' all the domains in pol that apply to 'metadata'
         * which are not already in domp
         */
        struct dev_policy *pol;
        pollist = pol_find(pollist, pol_domain);
        pol_for_each(pol, pollist, metadata)
                domain_merge_one(domp, pol->value);
}

int domain_test(struct domainlist *dom, struct dev_policy *pol,
                const char *metadata)
{
        /* Check that all domains in pol (for metadata) are also in
         * dom.  Both lists are sorted.
         * If pol has no domains, we don't really know about this device
         * so we reject the match.
         */
        int found_any = 0;
        struct dev_policy *p;

        pol = pol_find(pol, pol_domain);
        pol_for_each(p, pol, metadata) {
                found_any = 1;
                while (dom && strcmp(dom->dom, p->value) < 0)
                        dom = dom->next;
                if (!dom || strcmp(dom->dom, p->value) != 0)
                        return 0;
        }
        return found_any;
}

void domainlist_add_dev(struct domainlist **dom, int devnum, const char *metadata)
{
        struct dev_policy *pol = devnum_policy(devnum);
        domain_merge(dom, pol, metadata);
        dev_policy_free(pol);
}

struct domainlist *domain_from_array(struct mdinfo *mdi, const char *metadata)
{
        struct domainlist *domlist = NULL;

        for (mdi = mdi->devs ; mdi ; mdi = mdi->next)
                domainlist_add_dev(&domlist, makedev(mdi->disk.major,
                                                     mdi->disk.minor),
                                   metadata);

        return domlist;
}

void domain_add(struct domainlist **domp, char *domain)
{
        domain_merge_one(domp, domain);
}


void domain_free(struct domainlist *dl)
{
        while (dl) {
                struct domainlist *head = dl;
                dl = dl->next;
                free(head);
        }
}

/*
 * same-path policy.
 * Some policy decisions are guided by knowledge of which
 * array previously owned the device at a given physical location (path).
 * When removing a device from an array we might record the array against
 * the path, and when finding a new device, we might look for which
 * array previously used that path.
 *
 * The 'array' is described by a map_ent, and the path by a the disk in an
 * mdinfo, or a string.
 */

void policy_save_path(char *id_path, struct map_ent *array)
{
        char path[PATH_MAX];
        FILE *f = NULL;

        if (mkdir(FAILED_SLOTS_DIR, S_IRWXU) < 0 && errno != EEXIST) {
                fprintf(stderr, Name ": can't create file to save path "
                        "to old disk: %s\n", strerror(errno));
                return;
        }

        snprintf(path, PATH_MAX, FAILED_SLOTS_DIR "/%s", id_path);
        f = fopen(path, "w");
        if (!f) {
                fprintf(stderr, Name ": can't create file to"
                        " save path to old disk: %s\n",
                        strerror(errno));
                return;
        }

        if (fprintf(f, "%s %08x:%08x:%08x:%08x\n",
                    array->metadata,
                    array->uuid[0], array->uuid[1],
                    array->uuid[2], array->uuid[3]) <= 0)
                fprintf(stderr, Name ": Failed to write to "
                        "<id_path> cookie\n");

        fclose(f);
}

int policy_check_path(struct mdinfo *disk, struct map_ent *array)
{
        char path[PATH_MAX];
        FILE *f = NULL;
        char *id_path = disk_path(disk);
        int rv;

        if (!id_path)
                return 0;

        snprintf(path, PATH_MAX, FAILED_SLOTS_DIR "/%s", id_path);
        f = fopen(path, "r");
        if (!f)
                return 0;

        rv = fscanf(f, " %s %x:%x:%x:%x\n",
                    array->metadata,
                    array->uuid,
                    array->uuid+1,
                    array->uuid+2,
                    array->uuid+3);
        fclose(f);
        return rv == 5;
}