diff options
Diffstat (limited to 'msg.c')
| -rw-r--r-- | msg.c | 475 |
1 files changed, 475 insertions, 0 deletions
@@ -0,0 +1,475 @@ +/* + * Copyright (C) 2008 Intel Corporation + * + * mdmon socket / message handling + * + * 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. + */ +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif +#include <unistd.h> +#include <stdio.h> +#include <string.h> +#include <stdlib.h> +#include <errno.h> +#include <fcntl.h> +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/un.h> +#include "mdadm.h" +#include "mdmon.h" + +static const __u32 start_magic = 0x5a5aa5a5; +static const __u32 end_magic = 0xa5a55a5a; + +static int send_buf(int fd, const void* buf, int len, int tmo) +{ + fd_set set; + int rv; + struct timeval timeout = {tmo, 0}; + struct timeval *ptmo = tmo ? &timeout : NULL; + + while (len) { + FD_ZERO(&set); + FD_SET(fd, &set); + rv = select(fd+1, NULL, &set, NULL, ptmo); + if (rv <= 0) + return -1; + rv = write(fd, buf, len); + if (rv <= 0) + return -1; + len -= rv; + buf += rv; + } + return 0; +} + +static int recv_buf(int fd, void* buf, int len, int tmo) +{ + fd_set set; + int rv; + struct timeval timeout = {tmo, 0}; + struct timeval *ptmo = tmo ? &timeout : NULL; + + while (len) { + FD_ZERO(&set); + FD_SET(fd, &set); + rv = select(fd+1, &set, NULL, NULL, ptmo); + if (rv <= 0) + return -1; + rv = read(fd, buf, len); + if (rv <= 0) + return -1; + len -= rv; + buf += rv; + } + return 0; +} + +int send_message(int fd, struct metadata_update *msg, int tmo) +{ + __s32 len = msg->len; + int rv; + + rv = send_buf(fd, &start_magic, 4, tmo); + rv = rv ?: send_buf(fd, &len, 4, tmo); + if (len > 0) + rv = rv ?: send_buf(fd, msg->buf, msg->len, tmo); + rv = send_buf(fd, &end_magic, 4, tmo); + + return rv; +} + +int receive_message(int fd, struct metadata_update *msg, int tmo) +{ + __u32 magic; + __s32 len; + int rv; + + rv = recv_buf(fd, &magic, 4, tmo); + if (rv < 0 || magic != start_magic) + return -1; + rv = recv_buf(fd, &len, 4, tmo); + if (rv < 0 || len > MSG_MAX_LEN) + return -1; + if (len > 0) { + msg->buf = xmalloc(len); + rv = recv_buf(fd, msg->buf, len, tmo); + if (rv < 0) { + free(msg->buf); + return -1; + } + } else + msg->buf = NULL; + rv = recv_buf(fd, &magic, 4, tmo); + if (rv < 0 || magic != end_magic) { + free(msg->buf); + return -1; + } + msg->len = len; + return 0; +} + +int ack(int fd, int tmo) +{ + struct metadata_update msg = { .len = 0 }; + + return send_message(fd, &msg, tmo); +} + +int wait_reply(int fd, int tmo) +{ + struct metadata_update msg; + int err = receive_message(fd, &msg, tmo); + + /* mdmon sent extra data, but caller only cares that we got a + * successful reply + */ + if (err == 0 && msg.len > 0) + free(msg.buf); + + return err; +} + +int connect_monitor(char *devname) +{ + char path[100]; + int sfd; + long fl; + struct sockaddr_un addr; + int pos; + char *c; + + pos = sprintf(path, "%s/", MDMON_DIR); + if (is_subarray(devname)) { + devname++; + c = strchr(devname, '/'); + if (!c) + return -1; + snprintf(&path[pos], c - devname + 1, "%s", devname); + pos += c - devname; + } else + pos += sprintf(&path[pos], "%s", devname); + sprintf(&path[pos], ".sock"); + + sfd = socket(PF_LOCAL, SOCK_STREAM, 0); + if (sfd < 0) + return -1; + + addr.sun_family = PF_LOCAL; + strcpy(addr.sun_path, path); + if (connect(sfd, &addr, sizeof(addr)) < 0) { + close(sfd); + return -1; + } + + fl = fcntl(sfd, F_GETFL, 0); + fl |= O_NONBLOCK; + fcntl(sfd, F_SETFL, fl); + + return sfd; +} + +int fping_monitor(int sfd) +{ + int err = 0; + + if (sfd < 0) + return sfd; + + /* try to ping existing socket */ + if (ack(sfd, 20) != 0) + err = -1; + + /* check the reply */ + if (!err && wait_reply(sfd, 20) != 0) + err = -1; + + return err; +} + +/* give the monitor a chance to update the metadata */ +int ping_monitor(char *devname) +{ + int sfd = connect_monitor(devname); + int err; + + if (sfd >= 0) { + err = fping_monitor(sfd); + close(sfd); + } else + err = -1; + + return err; +} + +static char *ping_monitor_version(char *devname) +{ + int sfd = connect_monitor(devname); + struct metadata_update msg; + int err = 0; + + if (sfd < 0) + return NULL; + + if (ack(sfd, 20) != 0) + err = -1; + + if (!err && receive_message(sfd, &msg, 20) != 0) + err = -1; + + close(sfd); + + if (err || !msg.len || !msg.buf) + return NULL; + return msg.buf; +} + +int unblock_subarray(struct mdinfo *sra, const int unfreeze) +{ + char buf[64]; + int rc = 0; + + if (sra) { + sprintf(buf, "external:%s\n", sra->text_version); + buf[9] = '/'; + } else + buf[9] = '-'; + + if (buf[9] == '-' || + sysfs_set_str(sra, NULL, "metadata_version", buf) || + (unfreeze && + sysfs_attribute_available(sra, NULL, "sync_action") && + sysfs_set_str(sra, NULL, "sync_action", "idle"))) + rc = -1; + return rc; +} + +int block_subarray(struct mdinfo *sra) +{ + char buf[64]; + int rc = 0; + + sprintf(buf, "external:%s\n", sra->text_version); + buf[9] = '-'; + if (sysfs_set_str(sra, NULL, "metadata_version", buf)) + rc = -1; + + return rc; +} + +/* check mdmon version if it supports + * array blocking mechanism + */ +int check_mdmon_version(char *container) +{ + char *version = NULL; + + if (!mdmon_running(container)) { + /* if mdmon is not active we assume that any instance that is + * later started will match the current mdadm version, if this + * assumption is violated we may inadvertantly rebuild an array + * that was meant for reshape, or start rebuild on a spare that + * was to be moved to another container + */ + /* pass */; + } else { + int ver; + + version = ping_monitor_version(container); + ver = version ? mdadm_version(version) : -1; + free(version); + if (ver < 3002000) { + pr_err("mdmon instance for %s cannot be disabled\n", + container); + return -1; + } + } + + return 0; +} + +/** + * block_monitor - prevent mdmon spare assignment + * @container - container to block + * @freeze - flag to additionally freeze sync_action + * + * This is used by the reshape code to freeze the container, and the + * auto-rebuild implementation to atomically move spares. + * In both cases we need to stop mdmon from assigning spares to replace + * failed devices as we might have other plans for the spare. + * For the reshape case we also need to 'freeze' sync_action so that + * no recovery happens until we have fully prepared for the reshape. + * + * We tell mdmon that the array is frozen by marking the 'metadata' name + * with a leading '-'. The previously told mdmon "Don't make this array + * read/write, leave it readonly". Now it means a more general "Don't + * reconfigure this array at all". + * As older versions of mdmon (which might run from initrd) don't understand + * this, we first check that the running mdmon is new enough. + */ +int block_monitor(char *container, const int freeze) +{ + struct mdstat_ent *ent, *e, *e2; + struct mdinfo *sra = NULL; + char buf[64]; + int rv = 0; + + if (check_mdmon_version(container)) + return -1; + + ent = mdstat_read(0, 0); + if (!ent) { + pr_err("failed to read /proc/mdstat while disabling mdmon\n"); + return -1; + } + + /* freeze container contents */ + for (e = ent; e; e = e->next) { + if (!is_container_member(e, container)) + continue; + sysfs_free(sra); + sra = sysfs_read(-1, e->devnm, GET_VERSION); + if (!sra) { + pr_err("failed to read sysfs for subarray%s\n", + to_subarray(e, container)); + break; + } + /* can't reshape an array that we can't monitor */ + if (sra->text_version[0] == '-') + break; + + if (freeze && sysfs_freeze_array(sra) < 1) + break; + /* flag this array to not be modified by mdmon (close race with + * takeover in reshape case and spare reassignment in the + * auto-rebuild case) + */ + if (block_subarray(sra)) + break; + ping_monitor(container); + + /* check that we did not race with recovery */ + if ((freeze && + !sysfs_attribute_available(sra, NULL, "sync_action")) || + (freeze && + sysfs_attribute_available(sra, NULL, "sync_action") && + sysfs_get_str(sra, NULL, "sync_action", buf, 20) > 0 && + strcmp(buf, "frozen\n") == 0)) + /* pass */; + else { + unblock_subarray(sra, 0); + break; + } + /* Double check against races - there should be no spares + * or part-spares + */ + sysfs_free(sra); + sra = sysfs_read(-1, e->devnm, GET_DEVS | GET_STATE); + if (sra && sra->array.spare_disks > 0) { + unblock_subarray(sra, freeze); + break; + } + } + + if (e) { + pr_err("failed to freeze subarray%s\n", + to_subarray(e, container)); + + /* thaw the partially frozen container */ + for (e2 = ent; e2 && e2 != e; e2 = e2->next) { + if (!is_container_member(e2, container)) + continue; + sysfs_free(sra); + sra = sysfs_read(-1, e2->devnm, GET_VERSION); + if (unblock_subarray(sra, freeze)) + pr_err("Failed to unfreeze %s\n", e2->dev); + } + + ping_monitor(container); /* cleared frozen */ + rv = -1; + } + + sysfs_free(sra); + free_mdstat(ent); + + return rv; +} + +void unblock_monitor(char *container, const int unfreeze) +{ + struct mdstat_ent *ent, *e; + struct mdinfo *sra = NULL; + int to_ping = 0; + + ent = mdstat_read(0, 0); + if (!ent) { + pr_err("failed to read /proc/mdstat while unblocking container\n"); + return; + } + + /* unfreeze container contents */ + for (e = ent; e; e = e->next) { + if (!is_container_member(e, container)) + continue; + sysfs_free(sra); + sra = sysfs_read(-1, e->devnm, GET_VERSION|GET_LEVEL); + if (!sra) + continue; + if (sra->array.level > 0) + to_ping++; + if (unblock_subarray(sra, unfreeze)) + pr_err("Failed to unfreeze %s\n", e->dev); + } + if (to_ping) + ping_monitor(container); + + sysfs_free(sra); + free_mdstat(ent); +} + +/* give the manager a chance to view the updated container state. This + * would naturally happen due to the manager noticing a change in + * /proc/mdstat; however, pinging encourages this detection to happen + * while an exclusive open() on the container is active + */ +int ping_manager(char *devname) +{ + int sfd = connect_monitor(devname); + struct metadata_update msg = { .len = -1 }; + int err = 0; + + if (sfd < 0) + return sfd; + + err = send_message(sfd, &msg, 20); + + /* check the reply */ + if (!err && wait_reply(sfd, 20) != 0) + err = -1; + + close(sfd); + return err; +} + +/* using takeover operation for grow purposes, mdadm has to be sure + * that mdmon processes all updates, and if necessary it will be closed + * at takeover to raid0 operation + */ +void flush_mdmon(char *container) +{ + ping_manager(container); + ping_monitor(container); +} |