// SPDX-License-Identifier: GPL-2.0-or-later /* * Generic SCSI-3 ALUA SCSI Device Handler * * Copyright (C) 2007-2010 Hannes Reinecke, SUSE Linux Products GmbH. * All rights reserved. */ #include #include #include #include #include #include #include #include #include #define ALUA_DH_NAME "alua" #define ALUA_DH_VER "2.0" #define TPGS_SUPPORT_NONE 0x00 #define TPGS_SUPPORT_OPTIMIZED 0x01 #define TPGS_SUPPORT_NONOPTIMIZED 0x02 #define TPGS_SUPPORT_STANDBY 0x04 #define TPGS_SUPPORT_UNAVAILABLE 0x08 #define TPGS_SUPPORT_LBA_DEPENDENT 0x10 #define TPGS_SUPPORT_OFFLINE 0x40 #define TPGS_SUPPORT_TRANSITION 0x80 #define TPGS_SUPPORT_ALL 0xdf #define RTPG_FMT_MASK 0x70 #define RTPG_FMT_EXT_HDR 0x10 #define TPGS_MODE_UNINITIALIZED -1 #define TPGS_MODE_NONE 0x0 #define TPGS_MODE_IMPLICIT 0x1 #define TPGS_MODE_EXPLICIT 0x2 #define ALUA_RTPG_SIZE 128 #define ALUA_FAILOVER_TIMEOUT 60 #define ALUA_FAILOVER_RETRIES 5 #define ALUA_RTPG_DELAY_MSECS 5 #define ALUA_RTPG_RETRY_DELAY 2 /* device handler flags */ #define ALUA_OPTIMIZE_STPG 0x01 #define ALUA_RTPG_EXT_HDR_UNSUPP 0x02 /* State machine flags */ #define ALUA_PG_RUN_RTPG 0x10 #define ALUA_PG_RUN_STPG 0x20 #define ALUA_PG_RUNNING 0x40 static uint optimize_stpg; module_param(optimize_stpg, uint, S_IRUGO|S_IWUSR); MODULE_PARM_DESC(optimize_stpg, "Allow use of a non-optimized path, rather than sending a STPG, when implicit TPGS is supported (0=No,1=Yes). Default is 0."); static LIST_HEAD(port_group_list); static DEFINE_SPINLOCK(port_group_lock); static struct workqueue_struct *kaluad_wq; struct alua_port_group { struct kref kref; struct rcu_head rcu; struct list_head node; struct list_head dh_list; unsigned char device_id_str[256]; int device_id_len; int group_id; int tpgs; int state; int pref; int valid_states; unsigned flags; /* used for optimizing STPG */ unsigned char transition_tmo; unsigned long expiry; unsigned long interval; struct delayed_work rtpg_work; spinlock_t lock; struct list_head rtpg_list; struct scsi_device *rtpg_sdev; }; struct alua_dh_data { struct list_head node; struct alua_port_group __rcu *pg; int group_id; spinlock_t pg_lock; struct scsi_device *sdev; int init_error; struct mutex init_mutex; bool disabled; }; struct alua_queue_data { struct list_head entry; activate_complete callback_fn; void *callback_data; }; #define ALUA_POLICY_SWITCH_CURRENT 0 #define ALUA_POLICY_SWITCH_ALL 1 static void alua_rtpg_work(struct work_struct *work); static bool alua_rtpg_queue(struct alua_port_group *pg, struct scsi_device *sdev, struct alua_queue_data *qdata, bool force); static void alua_check(struct scsi_device *sdev, bool force); static void release_port_group(struct kref *kref) { struct alua_port_group *pg; pg = container_of(kref, struct alua_port_group, kref); if (pg->rtpg_sdev) flush_delayed_work(&pg->rtpg_work); spin_lock(&port_group_lock); list_del(&pg->node); spin_unlock(&port_group_lock); kfree_rcu(pg, rcu); } /* * submit_rtpg - Issue a REPORT TARGET GROUP STATES command * @sdev: sdev the command should be sent to */ static int submit_rtpg(struct scsi_device *sdev, unsigned char *buff, int bufflen, struct scsi_sense_hdr *sshdr, int flags) { u8 cdb[MAX_COMMAND_SIZE]; int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER; /* Prepare the command. */ memset(cdb, 0x0, MAX_COMMAND_SIZE); cdb[0] = MAINTENANCE_IN; if (!(flags & ALUA_RTPG_EXT_HDR_UNSUPP)) cdb[1] = MI_REPORT_TARGET_PGS | MI_EXT_HDR_PARAM_FMT; else cdb[1] = MI_REPORT_TARGET_PGS; put_unaligned_be32(bufflen, &cdb[6]); return scsi_execute(sdev, cdb, DMA_FROM_DEVICE, buff, bufflen, NULL, sshdr, ALUA_FAILOVER_TIMEOUT * HZ, ALUA_FAILOVER_RETRIES, req_flags, 0, NULL); } /* * submit_stpg - Issue a SET TARGET PORT GROUP command * * Currently we're only setting the current target port group state * to 'active/optimized' and let the array firmware figure out * the states of the remaining groups. */ static int submit_stpg(struct scsi_device *sdev, int group_id, struct scsi_sense_hdr *sshdr) { u8 cdb[MAX_COMMAND_SIZE]; unsigned char stpg_data[8]; int stpg_len = 8; int req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER; /* Prepare the data buffer */ memset(stpg_data, 0, stpg_len); stpg_data[4] = SCSI_ACCESS_STATE_OPTIMAL; put_unaligned_be16(group_id, &stpg_data[6]); /* Prepare the command. */ memset(cdb, 0x0, MAX_COMMAND_SIZE); cdb[0] = MAINTENANCE_OUT; cdb[1] = MO_SET_TARGET_PGS; put_unaligned_be32(stpg_len, &cdb[6]); return scsi_execute(sdev, cdb, DMA_TO_DEVICE, stpg_data, stpg_len, NULL, sshdr, ALUA_FAILOVER_TIMEOUT * HZ, ALUA_FAILOVER_RETRIES, req_flags, 0, NULL); } static struct alua_port_group *alua_find_get_pg(char *id_str, size_t id_size, int group_id) { struct alua_port_group *pg; if (!id_str || !id_size || !strlen(id_str)) return NULL; list_for_each_entry(pg, &port_group_list, node) { if (pg->group_id != group_id) continue; if (!pg->device_id_len || pg->device_id_len != id_size) continue; if (strncmp(pg->device_id_str, id_str, id_size)) continue; if (!kref_get_unless_zero(&pg->kref)) continue; return pg; } return NULL; } /* * alua_alloc_pg - Allocate a new port_group structure * @sdev: scsi device * @group_id: port group id * @tpgs: target port group settings * * Allocate a new port_group structure for a given * device. */ static struct alua_port_group *alua_alloc_pg(struct scsi_device *sdev, int group_id, int tpgs) { struct alua_port_group *pg, *tmp_pg; pg = kzalloc(sizeof(struct alua_port_group), GFP_KERNEL); if (!pg) return ERR_PTR(-ENOMEM); pg->device_id_len = scsi_vpd_lun_id(sdev, pg->device_id_str, sizeof(pg->device_id_str)); if (pg->device_id_len <= 0) { /* * TPGS supported but no device identification found. * Generate private device identification. */ sdev_printk(KERN_INFO, sdev, "%s: No device descriptors found\n", ALUA_DH_NAME); pg->device_id_str[0] = '\0'; pg->device_id_len = 0; } pg->group_id = group_id; pg->tpgs = tpgs; pg->state = SCSI_ACCESS_STATE_OPTIMAL; pg->valid_states = TPGS_SUPPORT_ALL; if (optimize_stpg) pg->flags |= ALUA_OPTIMIZE_STPG; kref_init(&pg->kref); INIT_DELAYED_WORK(&pg->rtpg_work, alua_rtpg_work); INIT_LIST_HEAD(&pg->rtpg_list); INIT_LIST_HEAD(&pg->node); INIT_LIST_HEAD(&pg->dh_list); spin_lock_init(&pg->lock); spin_lock(&port_group_lock); tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len, group_id); if (tmp_pg) { spin_unlock(&port_group_lock); kfree(pg); return tmp_pg; } list_add(&pg->node, &port_group_list); spin_unlock(&port_group_lock); return pg; } /* * alua_check_tpgs - Evaluate TPGS setting * @sdev: device to be checked * * Examine the TPGS setting of the sdev to find out if ALUA * is supported. */ static int alua_check_tpgs(struct scsi_device *sdev) { int tpgs = TPGS_MODE_NONE; /* * ALUA support for non-disk devices is fraught with * difficulties, so disable it for now. */ if (sdev->type != TYPE_DISK) { sdev_printk(KERN_INFO, sdev, "%s: disable for non-disk devices\n", ALUA_DH_NAME); return tpgs; } tpgs = scsi_device_tpgs(sdev); switch (tpgs) { case TPGS_MODE_EXPLICIT|TPGS_MODE_IMPLICIT: sdev_printk(KERN_INFO, sdev, "%s: supports implicit and explicit TPGS\n", ALUA_DH_NAME); break; case TPGS_MODE_EXPLICIT: sdev_printk(KERN_INFO, sdev, "%s: supports explicit TPGS\n", ALUA_DH_NAME); break; case TPGS_MODE_IMPLICIT: sdev_printk(KERN_INFO, sdev, "%s: supports implicit TPGS\n", ALUA_DH_NAME); break; case TPGS_MODE_NONE: sdev_printk(KERN_INFO, sdev, "%s: not supported\n", ALUA_DH_NAME); break; default: sdev_printk(KERN_INFO, sdev, "%s: unsupported TPGS setting %d\n", ALUA_DH_NAME, tpgs); tpgs = TPGS_MODE_NONE; break; } return tpgs; } /* * alua_check_vpd - Evaluate INQUIRY vpd page 0x83 * @sdev: device to be checked * * Extract the relative target port and the target port group * descriptor from the list of identificators. */ static int alua_check_vpd(struct scsi_device *sdev, struct alua_dh_data *h, int tpgs) { int rel_port = -1, group_id; struct alua_port_group *pg, *old_pg = NULL; bool pg_updated = false; unsigned long flags; group_id = scsi_vpd_tpg_id(sdev, &rel_port); if (group_id < 0) { /* * Internal error; TPGS supported but required * VPD identification descriptors not present. * Disable ALUA support */ sdev_printk(KERN_INFO, sdev, "%s: No target port descriptors found\n", ALUA_DH_NAME); return SCSI_DH_DEV_UNSUPP; } pg = alua_alloc_pg(sdev, group_id, tpgs); if (IS_ERR(pg)) { if (PTR_ERR(pg) == -ENOMEM) return SCSI_DH_NOMEM; return SCSI_DH_DEV_UNSUPP; } if (pg->device_id_len) sdev_printk(KERN_INFO, sdev, "%s: device %s port group %x rel port %x\n", ALUA_DH_NAME, pg->device_id_str, group_id, rel_port); else sdev_printk(KERN_INFO, sdev, "%s: port group %x rel port %x\n", ALUA_DH_NAME, group_id, rel_port); /* Check for existing port group references */ spin_lock(&h->pg_lock); old_pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)); if (old_pg != pg) { /* port group has changed. Update to new port group */ if (h->pg) { spin_lock_irqsave(&old_pg->lock, flags); list_del_rcu(&h->node); spin_unlock_irqrestore(&old_pg->lock, flags); } rcu_assign_pointer(h->pg, pg); pg_updated = true; } spin_lock_irqsave(&pg->lock, flags); if (pg_updated) list_add_rcu(&h->node, &pg->dh_list); spin_unlock_irqrestore(&pg->lock, flags); alua_rtpg_queue(rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)), sdev, NULL, true); spin_unlock(&h->pg_lock); if (old_pg) kref_put(&old_pg->kref, release_port_group); return SCSI_DH_OK; } static char print_alua_state(unsigned char state) { switch (state) { case SCSI_ACCESS_STATE_OPTIMAL: return 'A'; case SCSI_ACCESS_STATE_ACTIVE: return 'N'; case SCSI_ACCESS_STATE_STANDBY: return 'S'; case SCSI_ACCESS_STATE_UNAVAILABLE: return 'U'; case SCSI_ACCESS_STATE_LBA: return 'L'; case SCSI_ACCESS_STATE_OFFLINE: return 'O'; case SCSI_ACCESS_STATE_TRANSITIONING: return 'T'; default: return 'X'; } } static enum scsi_disposition alua_check_sense(struct scsi_device *sdev, struct scsi_sense_hdr *sense_hdr) { struct alua_dh_data *h = sdev->handler_data; struct alua_port_group *pg; switch (sense_hdr->sense_key) { case NOT_READY: if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x0a) { /* * LUN Not Accessible - ALUA state transition */ rcu_read_lock(); pg = rcu_dereference(h->pg); if (pg) pg->state = SCSI_ACCESS_STATE_TRANSITIONING; rcu_read_unlock(); alua_check(sdev, false); return NEEDS_RETRY; } break; case UNIT_ATTENTION: if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00) { /* * Power On, Reset, or Bus Device Reset. * Might have obscured a state transition, * so schedule a recheck. */ alua_check(sdev, true); return ADD_TO_MLQUEUE; } if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x04) /* * Device internal reset */ return ADD_TO_MLQUEUE; if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x01) /* * Mode Parameters Changed */ return ADD_TO_MLQUEUE; if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x06) { /* * ALUA state changed */ alua_check(sdev, true); return ADD_TO_MLQUEUE; } if (sense_hdr->asc == 0x2a && sense_hdr->ascq == 0x07) { /* * Implicit ALUA state transition failed */ alua_check(sdev, true); return ADD_TO_MLQUEUE; } if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x03) /* * Inquiry data has changed */ return ADD_TO_MLQUEUE; if (sense_hdr->asc == 0x3f && sense_hdr->ascq == 0x0e) /* * REPORTED_LUNS_DATA_HAS_CHANGED is reported * when switching controllers on targets like * Intel Multi-Flex. We can just retry. */ return ADD_TO_MLQUEUE; break; } return SCSI_RETURN_NOT_HANDLED; } /* * alua_tur - Send a TEST UNIT READY * @sdev: device to which the TEST UNIT READY command should be send * * Send a TEST UNIT READY to @sdev to figure out the device state * Returns SCSI_DH_RETRY if the sense code is NOT READY/ALUA TRANSITIONING, * SCSI_DH_OK if no error occurred, and SCSI_DH_IO otherwise. */ static int alua_tur(struct scsi_device *sdev) { struct scsi_sense_hdr sense_hdr; int retval; retval = scsi_test_unit_ready(sdev, ALUA_FAILOVER_TIMEOUT * HZ, ALUA_FAILOVER_RETRIES, &sense_hdr); if (sense_hdr.sense_key == NOT_READY && sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) return SCSI_DH_RETRY; else if (retval) return SCSI_DH_IO; else return SCSI_DH_OK; } /* * alua_rtpg - Evaluate REPORT TARGET GROUP STATES * @sdev: the device to be evaluated. * * Evaluate the Target Port Group State. * Returns SCSI_DH_DEV_OFFLINED if the path is * found to be unusable. */ static int alua_rtpg(struct scsi_device *sdev, struct alua_port_group *pg) { struct scsi_sense_hdr sense_hdr; struct alua_port_group *tmp_pg; int len, k, off, bufflen = ALUA_RTPG_SIZE; int group_id_old, state_old, pref_old, valid_states_old; unsigned char *desc, *buff; unsigned err, retval; unsigned int tpg_desc_tbl_off; unsigned char orig_transition_tmo; unsigned long flags; bool transitioning_sense = false; group_id_old = pg->group_id; state_old = pg->state; pref_old = pg->pref; valid_states_old = pg->valid_states; if (!pg->expiry) { unsigned long transition_tmo = ALUA_FAILOVER_TIMEOUT * HZ; if (pg->transition_tmo) transition_tmo = pg->transition_tmo * HZ; pg->expiry = round_jiffies_up(jiffies + transition_tmo); } buff = kzalloc(bufflen, GFP_KERNEL); if (!buff) return SCSI_DH_DEV_TEMP_BUSY; retry: err = 0; retval = submit_rtpg(sdev, buff, bufflen, &sense_hdr, pg->flags); if (retval) { /* * Some (broken) implementations have a habit of returning * an error during things like firmware update etc. * But if the target only supports active/optimized there's * not much we can do; it's not that we can switch paths * or anything. * So ignore any errors to avoid spurious failures during * path failover. */ if ((pg->valid_states & ~TPGS_SUPPORT_OPTIMIZED) == 0) { sdev_printk(KERN_INFO, sdev, "%s: ignoring rtpg result %d\n", ALUA_DH_NAME, retval); kfree(buff); return SCSI_DH_OK; } if (!scsi_sense_valid(&sense_hdr)) { sdev_printk(KERN_INFO, sdev, "%s: rtpg failed, result %d\n", ALUA_DH_NAME, retval); kfree(buff); if (driver_byte(retval) == DRIVER_ERROR) return SCSI_DH_DEV_TEMP_BUSY; if (host_byte(retval) == DID_NO_CONNECT) return SCSI_DH_RES_TEMP_UNAVAIL; return SCSI_DH_IO; } /* * submit_rtpg() has failed on existing arrays * when requesting extended header info, and * the array doesn't support extended headers, * even though it shouldn't according to T10. * The retry without rtpg_ext_hdr_req set * handles this. * Note: some arrays return a sense key of ILLEGAL_REQUEST * with ASC 00h if they don't support the extended header. */ if (!(pg->flags & ALUA_RTPG_EXT_HDR_UNSUPP) && sense_hdr.sense_key == ILLEGAL_REQUEST) { pg->flags |= ALUA_RTPG_EXT_HDR_UNSUPP; goto retry; } /* * If the array returns with 'ALUA state transition' * sense code here it cannot return RTPG data during * transition. So set the state to 'transitioning' directly. */ if (sense_hdr.sense_key == NOT_READY && sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) { transitioning_sense = true; goto skip_rtpg; } /* * Retry on any other UNIT ATTENTION occurred. */ if (sense_hdr.sense_key == UNIT_ATTENTION) err = SCSI_DH_RETRY; if (err == SCSI_DH_RETRY && pg->expiry != 0 && time_before(jiffies, pg->expiry)) { sdev_printk(KERN_ERR, sdev, "%s: rtpg retry\n", ALUA_DH_NAME); scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); kfree(buff); return err; } sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n", ALUA_DH_NAME); scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); kfree(buff); pg->expiry = 0; return SCSI_DH_IO; } len = get_unaligned_be32(&buff[0]) + 4; if (len > bufflen) { /* Resubmit with the correct length */ kfree(buff); bufflen = len; buff = kmalloc(bufflen, GFP_KERNEL); if (!buff) { sdev_printk(KERN_WARNING, sdev, "%s: kmalloc buffer failed\n",__func__); /* Temporary failure, bypass */ pg->expiry = 0; return SCSI_DH_DEV_TEMP_BUSY; } goto retry; } orig_transition_tmo = pg->transition_tmo; if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR && buff[5] != 0) pg->transition_tmo = buff[5]; else pg->transition_tmo = ALUA_FAILOVER_TIMEOUT; if (orig_transition_tmo != pg->transition_tmo) { sdev_printk(KERN_INFO, sdev, "%s: transition timeout set to %d seconds\n", ALUA_DH_NAME, pg->transition_tmo); pg->expiry = jiffies + pg->transition_tmo * HZ; } if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR) tpg_desc_tbl_off = 8; else tpg_desc_tbl_off = 4; for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off; k < len; k += off, desc += off) { u16 group_id = get_unaligned_be16(&desc[2]); spin_lock_irqsave(&port_group_lock, flags); tmp_pg = alua_find_get_pg(pg->device_id_str, pg->device_id_len, group_id); spin_unlock_irqrestore(&port_group_lock, flags); if (tmp_pg) { if (spin_trylock_irqsave(&tmp_pg->lock, flags)) { if ((tmp_pg == pg) || !(tmp_pg->flags & ALUA_PG_RUNNING)) { struct alua_dh_data *h; tmp_pg->state = desc[0] & 0x0f; tmp_pg->pref = desc[0] >> 7; rcu_read_lock(); list_for_each_entry_rcu(h, &tmp_pg->dh_list, node) { if (!h->sdev) continue; h->sdev->access_state = desc[0]; } rcu_read_unlock(); } if (tmp_pg == pg) tmp_pg->valid_states = desc[1]; spin_unlock_irqrestore(&tmp_pg->lock, flags); } kref_put(&tmp_pg->kref, release_port_group); } off = 8 + (desc[7] * 4); } skip_rtpg: spin_lock_irqsave(&pg->lock, flags); if (transitioning_sense) pg->state = SCSI_ACCESS_STATE_TRANSITIONING; if (group_id_old != pg->group_id || state_old != pg->state || pref_old != pg->pref || valid_states_old != pg->valid_states) sdev_printk(KERN_INFO, sdev, "%s: port group %02x state %c %s supports %c%c%c%c%c%c%c\n", ALUA_DH_NAME, pg->group_id, print_alua_state(pg->state), pg->pref ? "preferred" : "non-preferred", pg->valid_states&TPGS_SUPPORT_TRANSITION?'T':'t', pg->valid_states&TPGS_SUPPORT_OFFLINE?'O':'o', pg->valid_states&TPGS_SUPPORT_LBA_DEPENDENT?'L':'l', pg->valid_states&TPGS_SUPPORT_UNAVAILABLE?'U':'u', pg->valid_states&TPGS_SUPPORT_STANDBY?'S':'s', pg->valid_states&TPGS_SUPPORT_NONOPTIMIZED?'N':'n', pg->valid_states&TPGS_SUPPORT_OPTIMIZED?'A':'a'); switch (pg->state) { case SCSI_ACCESS_STATE_TRANSITIONING: if (time_before(jiffies, pg->expiry)) { /* State transition, retry */ pg->interval = ALUA_RTPG_RETRY_DELAY; err = SCSI_DH_RETRY; } else { struct alua_dh_data *h; /* Transitioning time exceeded, set port to standby */ err = SCSI_DH_IO; pg->state = SCSI_ACCESS_STATE_STANDBY; pg->expiry = 0; rcu_read_lock(); list_for_each_entry_rcu(h, &pg->dh_list, node) { if (!h->sdev) continue; h->sdev->access_state = (pg->state & SCSI_ACCESS_STATE_MASK); if (pg->pref) h->sdev->access_state |= SCSI_ACCESS_STATE_PREFERRED; } rcu_read_unlock(); } break; case SCSI_ACCESS_STATE_OFFLINE: /* Path unusable */ err = SCSI_DH_DEV_OFFLINED; pg->expiry = 0; break; default: /* Useable path if active */ err = SCSI_DH_OK; pg->expiry = 0; break; } spin_unlock_irqrestore(&pg->lock, flags); kfree(buff); return err; } /* * alua_stpg - Issue a SET TARGET PORT GROUP command * * Issue a SET TARGET PORT GROUP command and evaluate the * response. Returns SCSI_DH_RETRY per default to trigger * a re-evaluation of the target group state or SCSI_DH_OK * if no further action needs to be taken. */ static unsigned alua_stpg(struct scsi_device *sdev, struct alua_port_group *pg) { int retval; struct scsi_sense_hdr sense_hdr; if (!(pg->tpgs & TPGS_MODE_EXPLICIT)) { /* Only implicit ALUA supported, retry */ return SCSI_DH_RETRY; } switch (pg->state) { case SCSI_ACCESS_STATE_OPTIMAL: return SCSI_DH_OK; case SCSI_ACCESS_STATE_ACTIVE: if ((pg->flags & ALUA_OPTIMIZE_STPG) && !pg->pref && (pg->tpgs & TPGS_MODE_IMPLICIT)) return SCSI_DH_OK; break; case SCSI_ACCESS_STATE_STANDBY: case SCSI_ACCESS_STATE_UNAVAILABLE: break; case SCSI_ACCESS_STATE_OFFLINE: return SCSI_DH_IO; case SCSI_ACCESS_STATE_TRANSITIONING: break; default: sdev_printk(KERN_INFO, sdev, "%s: stpg failed, unhandled TPGS state %d", ALUA_DH_NAME, pg->state); return SCSI_DH_NOSYS; } retval = submit_stpg(sdev, pg->group_id, &sense_hdr); if (retval) { if (!scsi_sense_valid(&sense_hdr)) { sdev_printk(KERN_INFO, sdev, "%s: stpg failed, result %d", ALUA_DH_NAME, retval); if (driver_byte(retval) == DRIVER_ERROR) return SCSI_DH_DEV_TEMP_BUSY; } else { sdev_printk(KERN_INFO, sdev, "%s: stpg failed\n", ALUA_DH_NAME); scsi_print_sense_hdr(sdev, ALUA_DH_NAME, &sense_hdr); } } /* Retry RTPG */ return SCSI_DH_RETRY; } static bool alua_rtpg_select_sdev(struct alua_port_group *pg) { struct alua_dh_data *h; struct scsi_device *sdev = NULL; lockdep_assert_held(&pg->lock); if (WARN_ON(!pg->rtpg_sdev)) return false; /* * RCU protection isn't necessary for dh_list here * as we hold pg->lock, but for access to h->pg. */ rcu_read_lock(); list_for_each_entry_rcu(h, &pg->dh_list, node) { if (!h->sdev) continue; if (h->sdev == pg->rtpg_sdev) { h->disabled = true; continue; } if (rcu_dereference(h->pg) == pg && !h->disabled && !scsi_device_get(h->sdev)) { sdev = h->sdev; break; } } rcu_read_unlock(); if (!sdev) { pr_warn("%s: no device found for rtpg\n", (pg->device_id_len ? (char *)pg->device_id_str : "(nameless PG)")); return false; } sdev_printk(KERN_INFO, sdev, "rtpg retry on different device\n"); scsi_device_put(pg->rtpg_sdev); pg->rtpg_sdev = sdev; return true; } static void alua_rtpg_work(struct work_struct *work) { struct alua_port_group *pg = container_of(work, struct alua_port_group, rtpg_work.work); struct scsi_device *sdev; LIST_HEAD(qdata_list); int err = SCSI_DH_OK; struct alua_queue_data *qdata, *tmp; struct alua_dh_data *h; unsigned long flags; spin_lock_irqsave(&pg->lock, flags); sdev = pg->rtpg_sdev; if (!sdev) { WARN_ON(pg->flags & ALUA_PG_RUN_RTPG); WARN_ON(pg->flags & ALUA_PG_RUN_STPG); spin_unlock_irqrestore(&pg->lock, flags); kref_put(&pg->kref, release_port_group); return; } pg->flags |= ALUA_PG_RUNNING; if (pg->flags & ALUA_PG_RUN_RTPG) { int state = pg->state; pg->flags &= ~ALUA_PG_RUN_RTPG; spin_unlock_irqrestore(&pg->lock, flags); if (state == SCSI_ACCESS_STATE_TRANSITIONING) { if (alua_tur(sdev) == SCSI_DH_RETRY) { spin_lock_irqsave(&pg->lock, flags); pg->flags &= ~ALUA_PG_RUNNING; pg->flags |= ALUA_PG_RUN_RTPG; if (!pg->interval) pg->interval = ALUA_RTPG_RETRY_DELAY; spin_unlock_irqrestore(&pg->lock, flags); queue_delayed_work(kaluad_wq, &pg->rtpg_work, pg->interval * HZ); return; } /* Send RTPG on failure or if TUR indicates SUCCESS */ } err = alua_rtpg(sdev, pg); spin_lock_irqsave(&pg->lock, flags); /* If RTPG failed on the current device, try using another */ if (err == SCSI_DH_RES_TEMP_UNAVAIL && alua_rtpg_select_sdev(pg)) err = SCSI_DH_IMM_RETRY; if (err == SCSI_DH_RETRY || err == SCSI_DH_IMM_RETRY || pg->flags & ALUA_PG_RUN_RTPG) { pg->flags &= ~ALUA_PG_RUNNING; if (err == SCSI_DH_IMM_RETRY) pg->interval = 0; else if (!pg->interval && !(pg->flags & ALUA_PG_RUN_RTPG)) pg->interval = ALUA_RTPG_RETRY_DELAY; pg->flags |= ALUA_PG_RUN_RTPG; spin_unlock_irqrestore(&pg->lock, flags); queue_delayed_work(kaluad_wq, &pg->rtpg_work, pg->interval * HZ); return; } if (err != SCSI_DH_OK) pg->flags &= ~ALUA_PG_RUN_STPG; } if (pg->flags & ALUA_PG_RUN_STPG) { pg->flags &= ~ALUA_PG_RUN_STPG; spin_unlock_irqrestore(&pg->lock, flags); err = alua_stpg(sdev, pg); spin_lock_irqsave(&pg->lock, flags); if (err == SCSI_DH_RETRY || pg->flags & ALUA_PG_RUN_RTPG) { pg->flags |= ALUA_PG_RUN_RTPG; pg->interval = 0; pg->flags &= ~ALUA_PG_RUNNING; spin_unlock_irqrestore(&pg->lock, flags); queue_delayed_work(kaluad_wq, &pg->rtpg_work, pg->interval * HZ); return; } } list_splice_init(&pg->rtpg_list, &qdata_list); /* * We went through an RTPG, for good or bad. * Re-enable all devices for the next attempt. */ list_for_each_entry(h, &pg->dh_list, node) h->disabled = false; pg->rtpg_sdev = NULL; spin_unlock_irqrestore(&pg->lock, flags); list_for_each_entry_safe(qdata, tmp, &qdata_list, entry) { list_del(&qdata->entry); if (qdata->callback_fn) qdata->callback_fn(qdata->callback_data, err); kfree(qdata); } spin_lock_irqsave(&pg->lock, flags); pg->flags &= ~ALUA_PG_RUNNING; spin_unlock_irqrestore(&pg->lock, flags); scsi_device_put(sdev); kref_put(&pg->kref, release_port_group); } /** * alua_rtpg_queue() - cause RTPG to be submitted asynchronously * @pg: ALUA port group associated with @sdev. * @sdev: SCSI device for which to submit an RTPG. * @qdata: Information about the callback to invoke after the RTPG. * @force: Whether or not to submit an RTPG if a work item that will submit an * RTPG already has been scheduled. * * Returns true if and only if alua_rtpg_work() will be called asynchronously. * That function is responsible for calling @qdata->fn(). */ static bool alua_rtpg_queue(struct alua_port_group *pg, struct scsi_device *sdev, struct alua_queue_data *qdata, bool force) { int start_queue = 0; unsigned long flags; if (WARN_ON_ONCE(!pg) || scsi_device_get(sdev)) return false; spin_lock_irqsave(&pg->lock, flags); if (qdata) { list_add_tail(&qdata->entry, &pg->rtpg_list); pg->flags |= ALUA_PG_RUN_STPG; force = true; } if (pg->rtpg_sdev == NULL) { pg->interval = 0; pg->flags |= ALUA_PG_RUN_RTPG; kref_get(&pg->kref); pg->rtpg_sdev = sdev; start_queue = 1; } else if (!(pg->flags & ALUA_PG_RUN_RTPG) && force) { pg->flags |= ALUA_PG_RUN_RTPG; /* Do not queue if the worker is already running */ if (!(pg->flags & ALUA_PG_RUNNING)) { kref_get(&pg->kref); start_queue = 1; } } spin_unlock_irqrestore(&pg->lock, flags); if (start_queue) { if (queue_delayed_work(kaluad_wq, &pg->rtpg_work, msecs_to_jiffies(ALUA_RTPG_DELAY_MSECS))) sdev = NULL; else kref_put(&pg->kref, release_port_group); } if (sdev) scsi_device_put(sdev); return true; } /* * alua_initialize - Initialize ALUA state * @sdev: the device to be initialized * * For the prep_fn to work correctly we have * to initialize the ALUA state for the device. */ static int alua_initialize(struct scsi_device *sdev, struct alua_dh_data *h) { int err = SCSI_DH_DEV_UNSUPP, tpgs; mutex_lock(&h->init_mutex); h->disabled = false; tpgs = alua_check_tpgs(sdev); if (tpgs != TPGS_MODE_NONE) err = alua_check_vpd(sdev, h, tpgs); h->init_error = err; mutex_unlock(&h->init_mutex); return err; } /* * alua_set_params - set/unset the optimize flag * @sdev: device on the path to be activated * params - parameters in the following format * "no_of_params\0param1\0param2\0param3\0...\0" * For example, to set the flag pass the following parameters * from multipath.conf * hardware_handler "2 alua 1" */ static int alua_set_params(struct scsi_device *sdev, const char *params) { struct alua_dh_data *h = sdev->handler_data; struct alua_port_group *pg = NULL; unsigned int optimize = 0, argc; const char *p = params; int result = SCSI_DH_OK; unsigned long flags; if ((sscanf(params, "%u", &argc) != 1) || (argc != 1)) return -EINVAL; while (*p++) ; if ((sscanf(p, "%u", &optimize) != 1) || (optimize > 1)) return -EINVAL; rcu_read_lock(); pg = rcu_dereference(h->pg); if (!pg) { rcu_read_unlock(); return -ENXIO; } spin_lock_irqsave(&pg->lock, flags); if (optimize) pg->flags |= ALUA_OPTIMIZE_STPG; else pg->flags &= ~ALUA_OPTIMIZE_STPG; spin_unlock_irqrestore(&pg->lock, flags); rcu_read_unlock(); return result; } /* * alua_activate - activate a path * @sdev: device on the path to be activated * * We're currently switching the port group to be activated only and * let the array figure out the rest. * There may be other arrays which require us to switch all port groups * based on a certain policy. But until we actually encounter them it * should be okay. */ static int alua_activate(struct scsi_device *sdev, activate_complete fn, void *data) { struct alua_dh_data *h = sdev->handler_data; int err = SCSI_DH_OK; struct alua_queue_data *qdata; struct alua_port_group *pg; qdata = kzalloc(sizeof(*qdata), GFP_KERNEL); if (!qdata) { err = SCSI_DH_RES_TEMP_UNAVAIL; goto out; } qdata->callback_fn = fn; qdata->callback_data = data; mutex_lock(&h->init_mutex); rcu_read_lock(); pg = rcu_dereference(h->pg); if (!pg || !kref_get_unless_zero(&pg->kref)) { rcu_read_unlock(); kfree(qdata); err = h->init_error; mutex_unlock(&h->init_mutex); goto out; } rcu_read_unlock(); mutex_unlock(&h->init_mutex); if (alua_rtpg_queue(pg, sdev, qdata, true)) fn = NULL; else err = SCSI_DH_DEV_OFFLINED; kref_put(&pg->kref, release_port_group); out: if (fn) fn(data, err); return 0; } /* * alua_check - check path status * @sdev: device on the path to be checked * * Check the device status */ static void alua_check(struct scsi_device *sdev, bool force) { struct alua_dh_data *h = sdev->handler_data; struct alua_port_group *pg; rcu_read_lock(); pg = rcu_dereference(h->pg); if (!pg || !kref_get_unless_zero(&pg->kref)) { rcu_read_unlock(); return; } rcu_read_unlock(); alua_rtpg_queue(pg, sdev, NULL, force); kref_put(&pg->kref, release_port_group); } /* * alua_prep_fn - request callback * * Fail I/O to all paths not in state * active/optimized or active/non-optimized. */ static blk_status_t alua_prep_fn(struct scsi_device *sdev, struct request *req) { struct alua_dh_data *h = sdev->handler_data; struct alua_port_group *pg; unsigned char state = SCSI_ACCESS_STATE_OPTIMAL; rcu_read_lock(); pg = rcu_dereference(h->pg); if (pg) state = pg->state; rcu_read_unlock(); switch (state) { case SCSI_ACCESS_STATE_OPTIMAL: case SCSI_ACCESS_STATE_ACTIVE: case SCSI_ACCESS_STATE_LBA: return BLK_STS_OK; case SCSI_ACCESS_STATE_TRANSITIONING: return BLK_STS_AGAIN; default: req->rq_flags |= RQF_QUIET; return BLK_STS_IOERR; } } static void alua_rescan(struct scsi_device *sdev) { struct alua_dh_data *h = sdev->handler_data; alua_initialize(sdev, h); } /* * alua_bus_attach - Attach device handler * @sdev: device to be attached to */ static int alua_bus_attach(struct scsi_device *sdev) { struct alua_dh_data *h; int err; h = kzalloc(sizeof(*h) , GFP_KERNEL); if (!h) return SCSI_DH_NOMEM; spin_lock_init(&h->pg_lock); rcu_assign_pointer(h->pg, NULL); h->init_error = SCSI_DH_OK; h->sdev = sdev; INIT_LIST_HEAD(&h->node); mutex_init(&h->init_mutex); err = alua_initialize(sdev, h); if (err != SCSI_DH_OK && err != SCSI_DH_DEV_OFFLINED) goto failed; sdev->handler_data = h; return SCSI_DH_OK; failed: kfree(h); return err; } /* * alua_bus_detach - Detach device handler * @sdev: device to be detached from */ static void alua_bus_detach(struct scsi_device *sdev) { struct alua_dh_data *h = sdev->handler_data; struct alua_port_group *pg; spin_lock(&h->pg_lock); pg = rcu_dereference_protected(h->pg, lockdep_is_held(&h->pg_lock)); rcu_assign_pointer(h->pg, NULL); spin_unlock(&h->pg_lock); if (pg) { spin_lock_irq(&pg->lock); list_del_rcu(&h->node); spin_unlock_irq(&pg->lock); kref_put(&pg->kref, release_port_group); } sdev->handler_data = NULL; synchronize_rcu(); kfree(h); } static struct scsi_device_handler alua_dh = { .name = ALUA_DH_NAME, .module = THIS_MODULE, .attach = alua_bus_attach, .detach = alua_bus_detach, .prep_fn = alua_prep_fn, .check_sense = alua_check_sense, .activate = alua_activate, .rescan = alua_rescan, .set_params = alua_set_params, }; static int __init alua_init(void) { int r; kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0); if (!kaluad_wq) return -ENOMEM; r = scsi_register_device_handler(&alua_dh); if (r != 0) { printk(KERN_ERR "%s: Failed to register scsi device handler", ALUA_DH_NAME); destroy_workqueue(kaluad_wq); } return r; } static void __exit alua_exit(void) { scsi_unregister_device_handler(&alua_dh); destroy_workqueue(kaluad_wq); } module_init(alua_init); module_exit(alua_exit); MODULE_DESCRIPTION("DM Multipath ALUA support"); MODULE_AUTHOR("Hannes Reinecke "); MODULE_LICENSE("GPL"); MODULE_VERSION(ALUA_DH_VER);