/* * scsi_lib.c Copyright (C) 1999 Eric Youngdale * * SCSI queueing library. * Initial versions: Eric Youngdale (eric@andante.org). * Based upon conversations with large numbers * of people at Linux Expo. */ #include <linux/bio.h> #include <linux/blkdev.h> #include <linux/completion.h> #include <linux/kernel.h> #include <linux/mempool.h> #include <linux/slab.h> #include <linux/init.h> #include <linux/pci.h> #include <scsi/scsi_driver.h> #include <scsi/scsi_host.h> #include "scsi.h" #include "scsi_priv.h" #include "scsi_logging.h" #define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool)) #define SG_MEMPOOL_SIZE 32 struct scsi_host_sg_pool { size_t size; char *name; kmem_cache_t *slab; mempool_t *pool; }; #if (SCSI_MAX_PHYS_SEGMENTS < 32) #error SCSI_MAX_PHYS_SEGMENTS is too small #endif #define SP(x) { x, "sgpool-" #x } struct scsi_host_sg_pool scsi_sg_pools[] = { SP(8), SP(16), SP(32), #if (SCSI_MAX_PHYS_SEGMENTS > 32) SP(64), #if (SCSI_MAX_PHYS_SEGMENTS > 64) SP(128), #if (SCSI_MAX_PHYS_SEGMENTS > 128) SP(256), #if (SCSI_MAX_PHYS_SEGMENTS > 256) #error SCSI_MAX_PHYS_SEGMENTS is too large #endif #endif #endif #endif }; #undef SP /* * Function: scsi_insert_special_req() * * Purpose: Insert pre-formed request into request queue. * * Arguments: sreq - request that is ready to be queued. * at_head - boolean. True if we should insert at head * of queue, false if we should insert at tail. * * Lock status: Assumed that lock is not held upon entry. * * Returns: Nothing * * Notes: This function is called from character device and from * ioctl types of functions where the caller knows exactly * what SCSI command needs to be issued. The idea is that * we merely inject the command into the queue (at the head * for now), and then call the queue request function to actually * process it. */ int scsi_insert_special_req(struct scsi_request *sreq, int at_head) { /* * Because users of this function are apt to reuse requests with no * modification, we have to sanitise the request flags here */ sreq->sr_request->flags &= ~REQ_DONTPREP; blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request, at_head, sreq, 0); return 0; } /* * Function: scsi_queue_insert() * * Purpose: Insert a command in the midlevel queue. * * Arguments: cmd - command that we are adding to queue. * reason - why we are inserting command to queue. * * Lock status: Assumed that lock is not held upon entry. * * Returns: Nothing. * * Notes: We do this for one of two cases. Either the host is busy * and it cannot accept any more commands for the time being, * or the device returned QUEUE_FULL and can accept no more * commands. * Notes: This could be called either from an interrupt context or a * normal process context. */ int scsi_queue_insert(struct scsi_cmnd *cmd, int reason) { struct Scsi_Host *host = cmd->device->host; struct scsi_device *device = cmd->device; SCSI_LOG_MLQUEUE(1, printk("Inserting command %p into mlqueue\n", cmd)); /* * We are inserting the command into the ml queue. First, we * cancel the timer, so it doesn't time out. */ scsi_delete_timer(cmd); /* * Next, set the appropriate busy bit for the device/host. * * If the host/device isn't busy, assume that something actually * completed, and that we should be able to queue a command now. * * Note that the prior mid-layer assumption that any host could * always queue at least one command is now broken. The mid-layer * will implement a user specifiable stall (see * scsi_host.max_host_blocked and scsi_device.max_device_blocked) * if a command is requeued with no other commands outstanding * either for the device or for the host. */ if (reason == SCSI_MLQUEUE_HOST_BUSY) host->host_blocked = host->max_host_blocked; else if (reason == SCSI_MLQUEUE_DEVICE_BUSY) device->device_blocked = device->max_device_blocked; /* * Register the fact that we own the thing for now. */ cmd->state = SCSI_STATE_MLQUEUE; cmd->owner = SCSI_OWNER_MIDLEVEL; /* * Decrement the counters, since these commands are no longer * active on the host/device. */ scsi_device_unbusy(device); /* * Insert this command at the head of the queue for it's device. * It will go before all other commands that are already in the queue. * * NOTE: there is magic here about the way the queue is plugged if * we have no outstanding commands. * * Although this *doesn't* plug the queue, it does call the request * function. The SCSI request function detects the blocked condition * and plugs the queue appropriately. */ blk_insert_request(device->request_queue, cmd->request, 1, cmd, 1); return 0; } /* * Function: scsi_do_req * * Purpose: Queue a SCSI request * * Arguments: sreq - command descriptor. * cmnd - actual SCSI command to be performed. * buffer - data buffer. * bufflen - size of data buffer. * done - completion function to be run. * timeout - how long to let it run before timeout. * retries - number of retries we allow. * * Lock status: No locks held upon entry. * * Returns: Nothing. * * Notes: This function is only used for queueing requests for things * like ioctls and character device requests - this is because * we essentially just inject a request into the queue for the * device. * * In order to support the scsi_device_quiesce function, we * now inject requests on the *head* of the device queue * rather than the tail. */ void scsi_do_req(struct scsi_request *sreq, const void *cmnd, void *buffer, unsigned bufflen, void (*done)(struct scsi_cmnd *), int timeout, int retries) { /* * If the upper level driver is reusing these things, then * we should release the low-level block now. Another one will * be allocated later when this request is getting queued. */ __scsi_release_request(sreq); /* * Our own function scsi_done (which marks the host as not busy, * disables the timeout counter, etc) will be called by us or by the * scsi_hosts[host].queuecommand() function needs to also call * the completion function for the high level driver. */ memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd)); sreq->sr_bufflen = bufflen; sreq->sr_buffer = buffer; sreq->sr_allowed = retries; sreq->sr_done = done; sreq->sr_timeout_per_command = timeout; if (sreq->sr_cmd_len == 0) sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]); /* * head injection *required* here otherwise quiesce won't work */ scsi_insert_special_req(sreq, 1); } static void scsi_wait_done(struct scsi_cmnd *cmd) { struct request *req = cmd->request; struct request_queue *q = cmd->device->request_queue; unsigned long flags; req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */ spin_lock_irqsave(q->queue_lock, flags); if (blk_rq_tagged(req)) blk_queue_end_tag(q, req); spin_unlock_irqrestore(q->queue_lock, flags); if (req->waiting) complete(req->waiting); } void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer, unsigned bufflen, int timeout, int retries) { DECLARE_COMPLETION(wait); sreq->sr_request->waiting = &wait; sreq->sr_request->rq_status = RQ_SCSI_BUSY; scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done, timeout, retries); wait_for_completion(&wait); sreq->sr_request->waiting = NULL; if (sreq->sr_request->rq_status != RQ_SCSI_DONE) sreq->sr_result |= (DRIVER_ERROR << 24); __scsi_release_request(sreq); } /* * Function: scsi_init_cmd_errh() * * Purpose: Initialize cmd fields related to error handling. * * Arguments: cmd - command that is ready to be queued. * * Returns: Nothing * * Notes: This function has the job of initializing a number of * fields related to error handling. Typically this will * be called once for each command, as required. */ static int scsi_init_cmd_errh(struct scsi_cmnd *cmd) { cmd->owner = SCSI_OWNER_MIDLEVEL; cmd->serial_number = 0; cmd->serial_number_at_timeout = 0; cmd->abort_reason = 0; memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer); if (cmd->cmd_len == 0) cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]); /* * We need saved copies of a number of fields - this is because * error handling may need to overwrite these with different values * to run different commands, and once error handling is complete, * we will need to restore these values prior to running the actual * command. */ cmd->old_use_sg = cmd->use_sg; cmd->old_cmd_len = cmd->cmd_len; cmd->sc_old_data_direction = cmd->sc_data_direction; cmd->old_underflow = cmd->underflow; memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd)); cmd->buffer = cmd->request_buffer; cmd->bufflen = cmd->request_bufflen; cmd->internal_timeout = NORMAL_TIMEOUT; cmd->abort_reason = 0; return 1; } /* * Function: scsi_setup_cmd_retry() * * Purpose: Restore the command state for a retry * * Arguments: cmd - command to be restored * * Returns: Nothing * * Notes: Immediately prior to retrying a command, we need * to restore certain fields that we saved above. */ void scsi_setup_cmd_retry(struct scsi_cmnd *cmd) { memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd)); cmd->request_buffer = cmd->buffer; cmd->request_bufflen = cmd->bufflen; cmd->use_sg = cmd->old_use_sg; cmd->cmd_len = cmd->old_cmd_len; cmd->sc_data_direction = cmd->sc_old_data_direction; cmd->underflow = cmd->old_underflow; } void scsi_device_unbusy(struct scsi_device *sdev) { struct Scsi_Host *shost = sdev->host; unsigned long flags; spin_lock_irqsave(shost->host_lock, flags); shost->host_busy--; if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) && shost->host_failed)) scsi_eh_wakeup(shost); spin_unlock(shost->host_lock); spin_lock(&sdev->sdev_lock); sdev->device_busy--; spin_unlock_irqrestore(&sdev->sdev_lock, flags); } /* * Called for single_lun devices on IO completion. Clear starget_sdev_user, * and call blk_run_queue for all the scsi_devices on the target - * including current_sdev first. * * Called with *no* scsi locks held. */ static void scsi_single_lun_run(struct scsi_device *current_sdev) { struct Scsi_Host *shost = current_sdev->host; struct scsi_device *sdev, *tmp; unsigned long flags; spin_lock_irqsave(shost->host_lock, flags); current_sdev->sdev_target->starget_sdev_user = NULL; spin_unlock_irqrestore(shost->host_lock, flags); /* * Call blk_run_queue for all LUNs on the target, starting with * current_sdev. We race with others (to set starget_sdev_user), * but in most cases, we will be first. Ideally, each LU on the * target would get some limited time or requests on the target. */ blk_run_queue(current_sdev->request_queue); spin_lock_irqsave(shost->host_lock, flags); if (current_sdev->sdev_target->starget_sdev_user) goto out; list_for_each_entry_safe(sdev, tmp, ¤t_sdev->same_target_siblings, same_target_siblings) { if (scsi_device_get(sdev)) continue; spin_unlock_irqrestore(shost->host_lock, flags); blk_run_queue(sdev->request_queue); spin_lock_irqsave(shost->host_lock, flags); scsi_device_put(sdev); } out: spin_unlock_irqrestore(shost->host_lock, flags); } /* * Function: scsi_run_queue() * * Purpose: Select a proper request queue to serve next * * Arguments: q - last request's queue * * Returns: Nothing * * Notes: The previous command was completely finished, start * a new one if possible. */ static void scsi_run_queue(struct request_queue *q) { struct scsi_device *sdev = q->queuedata; struct Scsi_Host *shost = sdev->host; unsigned long flags; if (sdev->single_lun) scsi_single_lun_run(sdev); spin_lock_irqsave(shost->host_lock, flags); while (!list_empty(&shost->starved_list) && !shost->host_blocked && !shost->host_self_blocked && !((shost->can_queue > 0) && (shost->host_busy >= shost->can_queue))) { /* * As long as shost is accepting commands and we have * starved queues, call blk_run_queue. scsi_request_fn * drops the queue_lock and can add us back to the * starved_list. * * host_lock protects the starved_list and starved_entry. * scsi_request_fn must get the host_lock before checking * or modifying starved_list or starved_entry. */ sdev = list_entry(shost->starved_list.next, struct scsi_device, starved_entry); list_del_init(&sdev->starved_entry); spin_unlock_irqrestore(shost->host_lock, flags); blk_run_queue(sdev->request_queue); spin_lock_irqsave(shost->host_lock, flags); if (unlikely(!list_empty(&sdev->starved_entry))) /* * sdev lost a race, and was put back on the * starved list. This is unlikely but without this * in theory we could loop forever. */ break; } spin_unlock_irqrestore(shost->host_lock, flags); blk_run_queue(q); } /* * Function: scsi_requeue_command() * * Purpose: Handle post-processing of completed commands. * * Arguments: q - queue to operate on * cmd - command that may need to be requeued. * * Returns: Nothing * * Notes: After command completion, there may be blocks left * over which weren't finished by the previous command * this can be for a number of reasons - the main one is * I/O errors in the middle of the request, in which case * we need to request the blocks that come after the bad * sector. */ static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd) { cmd->request->flags &= ~REQ_DONTPREP; blk_insert_request(q, cmd->request, 1, cmd, 1); scsi_run_queue(q); } void scsi_next_command(struct scsi_cmnd *cmd) { struct request_queue *q = cmd->device->request_queue; scsi_put_command(cmd); scsi_run_queue(q); } void scsi_run_host_queues(struct Scsi_Host *shost) { struct scsi_device *sdev; shost_for_each_device(sdev, shost) scsi_run_queue(sdev->request_queue); } /* * Function: scsi_end_request() * * Purpose: Post-processing of completed commands called from interrupt * handler or a bottom-half handler. * * Arguments: cmd - command that is complete. * uptodate - 1 if I/O indicates success, 0 for I/O error. * sectors - number of sectors we want to mark. * requeue - indicates whether we should requeue leftovers. * frequeue - indicates that if we release the command block * that the queue request function should be called. * * Lock status: Assumed that lock is not held upon entry. * * Returns: Nothing * * Notes: This is called for block device requests in order to * mark some number of sectors as complete. * * We are guaranteeing that the request queue will be goosed * at some point during this call. */ static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate, int bytes, int requeue) { request_queue_t *q = cmd->device->request_queue; struct request *req = cmd->request; unsigned long flags; /* * If there are blocks left over at the end, set up the command * to queue the remainder of them. */ if (end_that_request_chunk(req, uptodate, bytes)) { int leftover = (req->hard_nr_sectors << 9); if (blk_pc_request(req)) leftover = req->data_len; /* kill remainder if no retrys */ if (!uptodate && blk_noretry_request(req)) end_that_request_chunk(req, 0, leftover); else { if (requeue) /* * Bleah. Leftovers again. Stick the * leftovers in the front of the * queue, and goose the queue again. */ scsi_requeue_command(q, cmd); return cmd; } } add_disk_randomness(req->rq_disk); spin_lock_irqsave(q->queue_lock, flags); if (blk_rq_tagged(req)) blk_queue_end_tag(q, req); end_that_request_last(req); spin_unlock_irqrestore(q->queue_lock, flags); /* * This will goose the queue request function at the end, so we don't * need to worry about launching another command. */ scsi_next_command(cmd); return NULL; } static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask) { struct scsi_host_sg_pool *sgp; struct scatterlist *sgl; BUG_ON(!cmd->use_sg); switch (cmd->use_sg) { case 1 ... 8: cmd->sglist_len = 0; break; case 9 ... 16: cmd->sglist_len = 1; break; case 17 ... 32: cmd->sglist_len = 2; break; #if (SCSI_MAX_PHYS_SEGMENTS > 32) case 33 ... 64: cmd->sglist_len = 3; break; #if (SCSI_MAX_PHYS_SEGMENTS > 64) case 65 ... 128: cmd->sglist_len = 4; break; #if (SCSI_MAX_PHYS_SEGMENTS > 128) case 129 ... 256: cmd->sglist_len = 5; break; #endif #endif #endif default: return NULL; } sgp = scsi_sg_pools + cmd->sglist_len; sgl = mempool_alloc(sgp->pool, gfp_mask); if (sgl) memset(sgl, 0, sgp->size); return sgl; } static void scsi_free_sgtable(struct scatterlist *sgl, int index) { struct scsi_host_sg_pool *sgp; BUG_ON(index > SG_MEMPOOL_NR); sgp = scsi_sg_pools + index; mempool_free(sgl, sgp->pool); } /* * Function: scsi_release_buffers() * * Purpose: Completion processing for block device I/O requests. * * Arguments: cmd - command that we are bailing. * * Lock status: Assumed that no lock is held upon entry. * * Returns: Nothing * * Notes: In the event that an upper level driver rejects a * command, we must release resources allocated during * the __init_io() function. Primarily this would involve * the scatter-gather table, and potentially any bounce * buffers. */ static void scsi_release_buffers(struct scsi_cmnd *cmd) { struct request *req = cmd->request; /* * Free up any indirection buffers we allocated for DMA purposes. */ if (cmd->use_sg) scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len); else if (cmd->request_buffer != req->buffer) kfree(cmd->request_buffer); /* * Zero these out. They now point to freed memory, and it is * dangerous to hang onto the pointers. */ cmd->buffer = NULL; cmd->bufflen = 0; cmd->request_buffer = NULL; cmd->request_bufflen = 0; } /* * Function: scsi_io_completion() * * Purpose: Completion processing for block device I/O requests. * * Arguments: cmd - command that is finished. * * Lock status: Assumed that no lock is held upon entry. * * Returns: Nothing * * Notes: This function is matched in terms of capabilities to * the function that created the scatter-gather list. * In other words, if there are no bounce buffers * (the normal case for most drivers), we don't need * the logic to deal with cleaning up afterwards. * * We must do one of several things here: * * a) Call scsi_end_request. This will finish off the * specified number of sectors. If we are done, the * command block will be released, and the queue * function will be goosed. If we are not done, then * scsi_end_request will directly goose the queue. * * b) We can just use scsi_requeue_command() here. This would * be used if we just wanted to retry, for example. */ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes, unsigned int block_bytes) { int result = cmd->result; int this_count = cmd->bufflen; request_queue_t *q = cmd->device->request_queue; struct request *req = cmd->request; int clear_errors = 1; /* * Free up any indirection buffers we allocated for DMA purposes. * For the case of a READ, we need to copy the data out of the * bounce buffer and into the real buffer. */ if (cmd->use_sg) scsi_free_sgtable(cmd->buffer, cmd->sglist_len); else if (cmd->buffer != req->buffer) { if (rq_data_dir(req) == READ) { unsigned long flags; char *to = bio_kmap_irq(req->bio, &flags); memcpy(to, cmd->buffer, cmd->bufflen); bio_kunmap_irq(to, &flags); } kfree(cmd->buffer); } if (blk_pc_request(req)) { /* SG_IO ioctl from block level */ req->errors = (driver_byte(result) & DRIVER_SENSE) ? (CHECK_CONDITION << 1) : (result & 0xff); if (result) { clear_errors = 0; if (cmd->sense_buffer[0] & 0x70) { int len = 8 + cmd->sense_buffer[7]; if (len > SCSI_SENSE_BUFFERSIZE) len = SCSI_SENSE_BUFFERSIZE; memcpy(req->sense, cmd->sense_buffer, len); req->sense_len = len; } } else req->data_len -= cmd->bufflen; } /* * Zero these out. They now point to freed memory, and it is * dangerous to hang onto the pointers. */ cmd->buffer = NULL; cmd->bufflen = 0; cmd->request_buffer = NULL; cmd->request_bufflen = 0; /* * Next deal with any sectors which we were able to correctly * handle. */ if (good_bytes >= 0) { SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n", req->nr_sectors, good_bytes)); SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg)); if (clear_errors) req->errors = 0; /* * If multiple sectors are requested in one buffer, then * they will have been finished off by the first command. * If not, then we have a multi-buffer command. * * If block_bytes != 0, it means we had a medium error * of some sort, and that we want to mark some number of * sectors as not uptodate. Thus we want to inhibit * requeueing right here - we will requeue down below * when we handle the bad sectors. */ cmd = scsi_end_request(cmd, 1, good_bytes, result == 0); /* * If the command completed without error, then either finish off the * rest of the command, or start a new one. */ if (result == 0 || cmd == NULL ) { return; } } /* * Now, if we were good little boys and girls, Santa left us a request * sense buffer. We can extract information from this, so we * can choose a block to remap, etc. */ if (driver_byte(result) != 0) { if ((cmd->sense_buffer[0] & 0x7f) == 0x70) { /* * If the device is in the process of becoming ready, * retry. */ if (cmd->sense_buffer[12] == 0x04 && cmd->sense_buffer[13] == 0x01) { scsi_requeue_command(q, cmd); return; } if ((cmd->sense_buffer[2] & 0xf) == UNIT_ATTENTION) { if (cmd->device->removable) { /* detected disc change. set a bit * and quietly refuse further access. */ cmd->device->changed = 1; cmd = scsi_end_request(cmd, 0, this_count, 1); return; } else { /* * Must have been a power glitch, or a * bus reset. Could not have been a * media change, so we just retry the * request and see what happens. */ scsi_requeue_command(q, cmd); return; } } } /* * If we had an ILLEGAL REQUEST returned, then we may have * performed an unsupported command. The only thing this * should be would be a ten byte read where only a six byte * read was supported. Also, on a system where READ CAPACITY * failed, we may have read past the end of the disk. */ switch (cmd->sense_buffer[2]) { case ILLEGAL_REQUEST: if (cmd->device->use_10_for_rw && (cmd->cmnd[0] == READ_10 || cmd->cmnd[0] == WRITE_10)) { cmd->device->use_10_for_rw = 0; /* * This will cause a retry with a 6-byte * command. */ scsi_requeue_command(q, cmd); result = 0; } else { cmd = scsi_end_request(cmd, 0, this_count, 1); return; } break; case NOT_READY: printk(KERN_INFO "Device %s not ready.\n", req->rq_disk ? req->rq_disk->disk_name : ""); cmd = scsi_end_request(cmd, 0, this_count, 1); return; break; case MEDIUM_ERROR: case VOLUME_OVERFLOW: printk("scsi%d: ERROR on channel %d, id %d, lun %d, CDB: ", cmd->device->host->host_no, (int) cmd->device->channel, (int) cmd->device->id, (int) cmd->device->lun); print_command(cmd->data_cmnd); print_sense("", cmd); cmd = scsi_end_request(cmd, 0, block_bytes, 1); return; default: break; } } /* driver byte != 0 */ if (host_byte(result) == DID_RESET) { /* * Third party bus reset or reset for error * recovery reasons. Just retry the request * and see what happens. */ scsi_requeue_command(q, cmd); return; } if (result) { printk("SCSI error : <%d %d %d %d> return code = 0x%x\n", cmd->device->host->host_no, cmd->device->channel, cmd->device->id, cmd->device->lun, result); if (driver_byte(result) & DRIVER_SENSE) print_sense("", cmd); /* * Mark a single buffer as not uptodate. Queue the remainder. * We sometimes get this cruft in the event that a medium error * isn't properly reported. */ block_bytes = req->hard_cur_sectors << 9; if (!block_bytes) block_bytes = req->data_len; cmd = scsi_end_request(cmd, 0, block_bytes, 1); } } /* * Function: scsi_init_io() * * Purpose: SCSI I/O initialize function. * * Arguments: cmd - Command descriptor we wish to initialize * * Returns: 0 on success * BLKPREP_DEFER if the failure is retryable * BLKPREP_KILL if the failure is fatal */ static int scsi_init_io(struct scsi_cmnd *cmd) { struct request *req = cmd->request; struct scatterlist *sgpnt; int count; /* * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer */ if ((req->flags & REQ_BLOCK_PC) && !req->bio) { cmd->request_bufflen = req->data_len; cmd->request_buffer = req->data; req->buffer = req->data; cmd->use_sg = 0; return 0; } /* * we used to not use scatter-gather for single segment request, * but now we do (it makes highmem I/O easier to support without * kmapping pages) */ cmd->use_sg = req->nr_phys_segments; /* * if sg table allocation fails, requeue request later. */ sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC); if (unlikely(!sgpnt)) { req->flags |= REQ_SPECIAL; return BLKPREP_DEFER; } cmd->request_buffer = (char *) sgpnt; cmd->request_bufflen = req->nr_sectors << 9; if (blk_pc_request(req)) cmd->request_bufflen = req->data_len; req->buffer = NULL; /* * Next, walk the list, and fill in the addresses and sizes of * each segment. */ count = blk_rq_map_sg(req->q, req, cmd->request_buffer); /* * mapped well, send it off */ if (likely(count <= cmd->use_sg)) { cmd->use_sg = count; return 0; } printk(KERN_ERR "Incorrect number of segments after building list\n"); printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg); printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors, req->current_nr_sectors); /* release the command and kill it */ scsi_release_buffers(cmd); scsi_put_command(cmd); return BLKPREP_KILL; } static int scsi_prep_fn(struct request_queue *q, struct request *req) { struct scsi_device *sdev = q->queuedata; struct scsi_cmnd *cmd; int specials_only = 0; /* * Just check to see if the device is online. If it isn't, we * refuse to process any commands. The device must be brought * online before trying any recovery commands */ if (unlikely(!scsi_device_online(sdev))) { printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n", sdev->host->host_no, sdev->id, sdev->lun); return BLKPREP_KILL; } if (unlikely(sdev->sdev_state != SDEV_RUNNING)) { /* OK, we're not in a running state don't prep * user commands */ if (sdev->sdev_state == SDEV_DEL) { /* Device is fully deleted, no commands * at all allowed down */ printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n", sdev->host->host_no, sdev->id, sdev->lun); return BLKPREP_KILL; } /* OK, we only allow special commands (i.e. not * user initiated ones */ specials_only = sdev->sdev_state; } /* * Find the actual device driver associated with this command. * The SPECIAL requests are things like character device or * ioctls, which did not originate from ll_rw_blk. Note that * the special field is also used to indicate the cmd for * the remainder of a partially fulfilled request that can * come up when there is a medium error. We have to treat * these two cases differently. We differentiate by looking * at request->cmd, as this tells us the real story. */ if (req->flags & REQ_SPECIAL) { struct scsi_request *sreq = req->special; if (sreq->sr_magic == SCSI_REQ_MAGIC) { cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC); if (unlikely(!cmd)) goto defer; scsi_init_cmd_from_req(cmd, sreq); } else cmd = req->special; } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) { if(unlikely(specials_only)) { if(specials_only == SDEV_QUIESCE) return BLKPREP_DEFER; printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n", sdev->host->host_no, sdev->id, sdev->lun); return BLKPREP_KILL; } /* * Now try and find a command block that we can use. */ if (!req->special) { cmd = scsi_get_command(sdev, GFP_ATOMIC); if (unlikely(!cmd)) goto defer; } else cmd = req->special; /* pull a tag out of the request if we have one */ cmd->tag = req->tag; } else { blk_dump_rq_flags(req, "SCSI bad req"); return BLKPREP_KILL; } /* note the overloading of req->special. When the tag * is active it always means cmd. If the tag goes * back for re-queueing, it may be reset */ req->special = cmd; cmd->request = req; /* * FIXME: drop the lock here because the functions below * expect to be called without the queue lock held. Also, * previously, we dequeued the request before dropping the * lock. We hope REQ_STARTED prevents anything untoward from * happening now. */ if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) { struct scsi_driver *drv; int ret; /* * This will do a couple of things: * 1) Fill in the actual SCSI command. * 2) Fill in any other upper-level specific fields * (timeout). * * If this returns 0, it means that the request failed * (reading past end of disk, reading offline device, * etc). This won't actually talk to the device, but * some kinds of consistency checking may cause the * request to be rejected immediately. */ /* * This sets up the scatter-gather table (allocating if * required). */ ret = scsi_init_io(cmd); if (ret) /* BLKPREP_KILL return also releases the command */ return ret; /* * Initialize the actual SCSI command for this request. */ drv = *(struct scsi_driver **)req->rq_disk->private_data; if (unlikely(!drv->init_command(cmd))) { scsi_release_buffers(cmd); scsi_put_command(cmd); return BLKPREP_KILL; } } /* * The request is now prepped, no need to come back here */ req->flags |= REQ_DONTPREP; return BLKPREP_OK; defer: /* If we defer, the elv_next_request() returns NULL, but the * queue must be restarted, so we plug here if no returning * command will automatically do that. */ if (sdev->device_busy == 0) blk_plug_device(q); return BLKPREP_DEFER; } /* * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else * return 0. * * Called with the queue_lock held. */ static inline int scsi_dev_queue_ready(struct request_queue *q, struct scsi_device *sdev) { if (sdev->device_busy >= sdev->queue_depth) return 0; if (sdev->device_busy == 0 && sdev->device_blocked) { /* * unblock after device_blocked iterates to zero */ if (--sdev->device_blocked == 0) { SCSI_LOG_MLQUEUE(3, printk("scsi%d (%d:%d) unblocking device at" " zero depth\n", sdev->host->host_no, sdev->id, sdev->lun)); } else { blk_plug_device(q); return 0; } } if (sdev->device_blocked) return 0; return 1; } /* * scsi_host_queue_ready: if we can send requests to shost, return 1 else * return 0. We must end up running the queue again whenever 0 is * returned, else IO can hang. * * Called with host_lock held. */ static inline int scsi_host_queue_ready(struct request_queue *q, struct Scsi_Host *shost, struct scsi_device *sdev) { if (test_bit(SHOST_RECOVERY, &shost->shost_state)) return 0; if (shost->host_busy == 0 && shost->host_blocked) { /* * unblock after host_blocked iterates to zero */ if (--shost->host_blocked == 0) { SCSI_LOG_MLQUEUE(3, printk("scsi%d unblocking host at zero depth\n", shost->host_no)); } else { blk_plug_device(q); return 0; } } if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) || shost->host_blocked || shost->host_self_blocked) { if (list_empty(&sdev->starved_entry)) list_add_tail(&sdev->starved_entry, &shost->starved_list); return 0; } /* We're OK to process the command, so we can't be starved */ if (!list_empty(&sdev->starved_entry)) list_del_init(&sdev->starved_entry); return 1; } /* * Function: scsi_request_fn() * * Purpose: Main strategy routine for SCSI. * * Arguments: q - Pointer to actual queue. * * Returns: Nothing * * Lock status: IO request lock assumed to be held when called. */ static void scsi_request_fn(struct request_queue *q) { struct scsi_device *sdev = q->queuedata; struct Scsi_Host *shost = sdev->host; struct scsi_cmnd *cmd; struct request *req; if(!get_device(&sdev->sdev_gendev)) /* We must be tearing the block queue down already */ return; /* * To start with, we keep looping until the queue is empty, or until * the host is no longer able to accept any more requests. */ while (!blk_queue_plugged(q)) { int rtn; /* * get next queueable request. We do this early to make sure * that the request is fully prepared even if we cannot * accept it. */ req = elv_next_request(q); if (!req || !scsi_dev_queue_ready(q, sdev)) break; if (unlikely(!scsi_device_online(sdev))) { printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n", sdev->host->host_no, sdev->id, sdev->lun); blkdev_dequeue_request(req); req->flags |= REQ_QUIET; while (end_that_request_first(req, 0, req->nr_sectors)) ; end_that_request_last(req); continue; } /* * Remove the request from the request list. */ if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req))) blkdev_dequeue_request(req); sdev->device_busy++; spin_unlock(q->queue_lock); spin_lock(shost->host_lock); if (!scsi_host_queue_ready(q, shost, sdev)) goto not_ready; if (sdev->single_lun) { if (sdev->sdev_target->starget_sdev_user && sdev->sdev_target->starget_sdev_user != sdev) goto not_ready; sdev->sdev_target->starget_sdev_user = sdev; } shost->host_busy++; /* * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will * take the lock again. */ spin_unlock_irq(shost->host_lock); cmd = req->special; if (unlikely(cmd == NULL)) { printk(KERN_CRIT "impossible request in %s.\n" "please mail a stack trace to " "linux-scsi@vger.kernel.org", __FUNCTION__); BUG(); } /* * Finally, initialize any error handling parameters, and set up * the timers for timeouts. */ scsi_init_cmd_errh(cmd); /* * Dispatch the command to the low-level driver. */ rtn = scsi_dispatch_cmd(cmd); spin_lock_irq(q->queue_lock); if(rtn) { /* we're refusing the command; because of * the way locks get dropped, we need to * check here if plugging is required */ if(sdev->device_busy == 0) blk_plug_device(q); break; } } goto out; not_ready: spin_unlock_irq(shost->host_lock); /* * lock q, handle tag, requeue req, and decrement device_busy. We * must return with queue_lock held. * * Decrementing device_busy without checking it is OK, as all such * cases (host limits or settings) should run the queue at some * later time. */ spin_lock_irq(q->queue_lock); blk_requeue_request(q, req); sdev->device_busy--; if(sdev->device_busy == 0) blk_plug_device(q); out: /* must be careful here...if we trigger the ->remove() function * we cannot be holding the q lock */ spin_unlock_irq(q->queue_lock); put_device(&sdev->sdev_gendev); spin_lock_irq(q->queue_lock); } u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) { struct device *host_dev; if (shost->unchecked_isa_dma) return BLK_BOUNCE_ISA; host_dev = scsi_get_device(shost); if (PCI_DMA_BUS_IS_PHYS && host_dev && host_dev->dma_mask) return *host_dev->dma_mask; /* * Platforms with virtual-DMA translation * hardware have no practical limit. */ return BLK_BOUNCE_ANY; } struct request_queue *scsi_alloc_queue(struct scsi_device *sdev) { struct Scsi_Host *shost = sdev->host; struct request_queue *q; q = blk_init_queue(scsi_request_fn, &sdev->sdev_lock); if (!q) return NULL; blk_queue_prep_rq(q, scsi_prep_fn); blk_queue_max_hw_segments(q, shost->sg_tablesize); blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS); blk_queue_max_sectors(q, shost->max_sectors); blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost)); blk_queue_segment_boundary(q, shost->dma_boundary); if (!shost->use_clustering) clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags); return q; } void scsi_free_queue(struct request_queue *q) { blk_cleanup_queue(q); } /* * Function: scsi_block_requests() * * Purpose: Utility function used by low-level drivers to prevent further * commands from being queued to the device. * * Arguments: shost - Host in question * * Returns: Nothing * * Lock status: No locks are assumed held. * * Notes: There is no timer nor any other means by which the requests * get unblocked other than the low-level driver calling * scsi_unblock_requests(). */ void scsi_block_requests(struct Scsi_Host *shost) { shost->host_self_blocked = 1; } /* * Function: scsi_unblock_requests() * * Purpose: Utility function used by low-level drivers to allow further * commands from being queued to the device. * * Arguments: shost - Host in question * * Returns: Nothing * * Lock status: No locks are assumed held. * * Notes: There is no timer nor any other means by which the requests * get unblocked other than the low-level driver calling * scsi_unblock_requests(). * * This is done as an API function so that changes to the * internals of the scsi mid-layer won't require wholesale * changes to drivers that use this feature. */ void scsi_unblock_requests(struct Scsi_Host *shost) { shost->host_self_blocked = 0; scsi_run_host_queues(shost); } int __init scsi_init_queue(void) { int i; for (i = 0; i < SG_MEMPOOL_NR; i++) { struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; int size = sgp->size * sizeof(struct scatterlist); sgp->slab = kmem_cache_create(sgp->name, size, 0, SLAB_HWCACHE_ALIGN, NULL, NULL); if (!sgp->slab) { printk(KERN_ERR "SCSI: can't init sg slab %s\n", sgp->name); } sgp->pool = mempool_create(SG_MEMPOOL_SIZE, mempool_alloc_slab, mempool_free_slab, sgp->slab); if (!sgp->pool) { printk(KERN_ERR "SCSI: can't init sg mempool %s\n", sgp->name); } } return 0; } void scsi_exit_queue(void) { int i; for (i = 0; i < SG_MEMPOOL_NR; i++) { struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; mempool_destroy(sgp->pool); kmem_cache_destroy(sgp->slab); } } /** * __scsi_mode_sense - issue a mode sense, falling back from 10 to * six bytes if necessary. * @sreq: SCSI request to fill in with the MODE_SENSE * @dbd: set if mode sense will allow block descriptors to be returned * @modepage: mode page being requested * @buffer: request buffer (may not be smaller than eight bytes) * @len: length of request buffer. * @timeout: command timeout * @retries: number of retries before failing * @data: returns a structure abstracting the mode header data * * Returns zero if unsuccessful, or the header offset (either 4 * or 8 depending on whether a six or ten byte command was * issued) if successful. **/ int __scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage, unsigned char *buffer, int len, int timeout, int retries, struct scsi_mode_data *data) { unsigned char cmd[12]; int use_10_for_ms; int header_length; memset(data, 0, sizeof(*data)); memset(&cmd[0], 0, 12); cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */ cmd[2] = modepage; retry: use_10_for_ms = sreq->sr_device->use_10_for_ms; if (use_10_for_ms) { if (len < 8) len = 8; cmd[0] = MODE_SENSE_10; cmd[8] = len; header_length = 8; } else { if (len < 4) len = 4; cmd[0] = MODE_SENSE; cmd[4] = len; header_length = 4; } sreq->sr_cmd_len = 0; sreq->sr_sense_buffer[0] = 0; sreq->sr_sense_buffer[2] = 0; sreq->sr_data_direction = DMA_FROM_DEVICE; memset(buffer, 0, len); scsi_wait_req(sreq, cmd, buffer, len, timeout, retries); /* This code looks awful: what it's doing is making sure an * ILLEGAL REQUEST sense return identifies the actual command * byte as the problem. MODE_SENSE commands can return * ILLEGAL REQUEST if the code page isn't supported */ if (use_10_for_ms && ! scsi_status_is_good(sreq->sr_result) && (driver_byte(sreq->sr_result) & DRIVER_SENSE) && sreq->sr_sense_buffer[2] == ILLEGAL_REQUEST && (sreq->sr_sense_buffer[4] & 0x40) == 0x40 && sreq->sr_sense_buffer[5] == 0 && sreq->sr_sense_buffer[6] == 0 ) { sreq->sr_device->use_10_for_ms = 0; goto retry; } if(scsi_status_is_good(sreq->sr_result)) { data->header_length = header_length; if(use_10_for_ms) { data->length = buffer[0]*256 + buffer[1] + 2; data->medium_type = buffer[2]; data->device_specific = buffer[3]; data->longlba = buffer[4] & 0x01; data->block_descriptor_length = buffer[6]*256 + buffer[7]; } else { data->length = buffer[0] + 1; data->medium_type = buffer[1]; data->device_specific = buffer[2]; data->block_descriptor_length = buffer[3]; } } return sreq->sr_result; } /** * scsi_mode_sense - issue a mode sense, falling back from 10 to * six bytes if necessary. * @sdev: scsi device to send command to. * @dbd: set if mode sense will disable block descriptors in the return * @modepage: mode page being requested * @buffer: request buffer (may not be smaller than eight bytes) * @len: length of request buffer. * @timeout: command timeout * @retries: number of retries before failing * * Returns zero if unsuccessful, or the header offset (either 4 * or 8 depending on whether a six or ten byte command was * issued) if successful. **/ int scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, unsigned char *buffer, int len, int timeout, int retries, struct scsi_mode_data *data) { struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL); int ret; if (!sreq) return -1; ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len, timeout, retries, data); scsi_release_request(sreq); return ret; } /** * scsi_device_set_state - Take the given device through the device * state model. * @sdev: scsi device to change the state of. * @state: state to change to. * * Returns zero if unsuccessful or an error if the requested * transition is illegal. **/ int scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state) { enum scsi_device_state oldstate = sdev->sdev_state; if (state == oldstate) return 0; switch (state) { case SDEV_CREATED: /* There are no legal states that come back to * created. This is the manually initialised start * state */ goto illegal; case SDEV_RUNNING: switch (oldstate) { case SDEV_CREATED: case SDEV_OFFLINE: case SDEV_QUIESCE: break; default: goto illegal; } break; case SDEV_QUIESCE: switch (oldstate) { case SDEV_RUNNING: case SDEV_OFFLINE: break; default: goto illegal; } break; case SDEV_OFFLINE: switch (oldstate) { case SDEV_CREATED: case SDEV_RUNNING: case SDEV_QUIESCE: break; default: goto illegal; } break; case SDEV_CANCEL: switch (oldstate) { case SDEV_CREATED: case SDEV_RUNNING: case SDEV_OFFLINE: break; default: goto illegal; } break; case SDEV_DEL: switch (oldstate) { case SDEV_CANCEL: break; default: goto illegal; } break; } sdev->sdev_state = state; return 0; illegal: dev_printk(KERN_ERR, &sdev->sdev_gendev, "Illegal state transition %s->%s\n", scsi_device_state_name(oldstate), scsi_device_state_name(state)); WARN_ON(1); return -EINVAL; } EXPORT_SYMBOL(scsi_device_set_state); /** * scsi_device_quiesce - Block user issued commands. * @sdev: scsi device to quiesce. * * This works by trying to transition to the SDEV_QUIESCE state * (which must be a legal transition). When the device is in this * state, only special requests will be accepted, all others will * be deferred. Since special requests may also be requeued requests, * a successful return doesn't guarantee the device will be * totally quiescent. * * Must be called with user context, may sleep. * * Returns zero if unsuccessful or an error if not. **/ int scsi_device_quiesce(struct scsi_device *sdev) { int err = scsi_device_set_state(sdev, SDEV_QUIESCE); if (err) return err; scsi_run_queue(sdev->request_queue); while (sdev->device_busy) { schedule_timeout(HZ/5); scsi_run_queue(sdev->request_queue); } return 0; } EXPORT_SYMBOL(scsi_device_quiesce); /** * scsi_device_resume - Restart user issued commands to a quiesced device. * @sdev: scsi device to resume. * * Moves the device from quiesced back to running and restarts the * queues. * * Must be called with user context, may sleep. **/ void scsi_device_resume(struct scsi_device *sdev) { if(scsi_device_set_state(sdev, SDEV_RUNNING)) return; scsi_run_queue(sdev->request_queue); } EXPORT_SYMBOL(scsi_device_resume);