diff options
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 3147 |
1 files changed, 3147 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c new file mode 100644 index 000000000..b1a263137 --- /dev/null +++ b/drivers/scsi/scsi_lib.c @@ -0,0 +1,3147 @@ +/* + * Copyright (C) 1999 Eric Youngdale + * Copyright (C) 2014 Christoph Hellwig + * + * 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/bitops.h> +#include <linux/blkdev.h> +#include <linux/completion.h> +#include <linux/kernel.h> +#include <linux/export.h> +#include <linux/mempool.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/pci.h> +#include <linux/delay.h> +#include <linux/hardirq.h> +#include <linux/scatterlist.h> +#include <linux/blk-mq.h> +#include <linux/ratelimit.h> + +#include <scsi/scsi.h> +#include <scsi/scsi_cmnd.h> +#include <scsi/scsi_dbg.h> +#include <scsi/scsi_device.h> +#include <scsi/scsi_driver.h> +#include <scsi/scsi_eh.h> +#include <scsi/scsi_host.h> + +#include <trace/events/scsi.h> + +#include "scsi_priv.h" +#include "scsi_logging.h" + + +#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools) +#define SG_MEMPOOL_SIZE 2 + +struct scsi_host_sg_pool { + size_t size; + char *name; + struct kmem_cache *slab; + mempool_t *pool; +}; + +#define SP(x) { .size = x, "sgpool-" __stringify(x) } +#if (SCSI_MAX_SG_SEGMENTS < 32) +#error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater) +#endif +static struct scsi_host_sg_pool scsi_sg_pools[] = { + SP(8), + SP(16), +#if (SCSI_MAX_SG_SEGMENTS > 32) + SP(32), +#if (SCSI_MAX_SG_SEGMENTS > 64) + SP(64), +#if (SCSI_MAX_SG_SEGMENTS > 128) + SP(128), +#if (SCSI_MAX_SG_SEGMENTS > 256) +#error SCSI_MAX_SG_SEGMENTS is too large (256 MAX) +#endif +#endif +#endif +#endif + SP(SCSI_MAX_SG_SEGMENTS) +}; +#undef SP + +struct kmem_cache *scsi_sdb_cache; + +/* + * When to reinvoke queueing after a resource shortage. It's 3 msecs to + * not change behaviour from the previous unplug mechanism, experimentation + * may prove this needs changing. + */ +#define SCSI_QUEUE_DELAY 3 + +static void +scsi_set_blocked(struct scsi_cmnd *cmd, int reason) +{ + struct Scsi_Host *host = cmd->device->host; + struct scsi_device *device = cmd->device; + struct scsi_target *starget = scsi_target(device); + + /* + * 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. + */ + switch (reason) { + case SCSI_MLQUEUE_HOST_BUSY: + atomic_set(&host->host_blocked, host->max_host_blocked); + break; + case SCSI_MLQUEUE_DEVICE_BUSY: + case SCSI_MLQUEUE_EH_RETRY: + atomic_set(&device->device_blocked, + device->max_device_blocked); + break; + case SCSI_MLQUEUE_TARGET_BUSY: + atomic_set(&starget->target_blocked, + starget->max_target_blocked); + break; + } +} + +static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd) +{ + struct scsi_device *sdev = cmd->device; + struct request_queue *q = cmd->request->q; + + blk_mq_requeue_request(cmd->request); + blk_mq_kick_requeue_list(q); + put_device(&sdev->sdev_gendev); +} + +/** + * __scsi_queue_insert - private queue insertion + * @cmd: The SCSI command being requeued + * @reason: The reason for the requeue + * @unbusy: Whether the queue should be unbusied + * + * This is a private queue insertion. The public interface + * scsi_queue_insert() always assumes the queue should be unbusied + * because it's always called before the completion. This function is + * for a requeue after completion, which should only occur in this + * file. + */ +static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy) +{ + struct scsi_device *device = cmd->device; + struct request_queue *q = device->request_queue; + unsigned long flags; + + SCSI_LOG_MLQUEUE(1, scmd_printk(KERN_INFO, cmd, + "Inserting command %p into mlqueue\n", cmd)); + + scsi_set_blocked(cmd, reason); + + /* + * Decrement the counters, since these commands are no longer + * active on the host/device. + */ + if (unbusy) + scsi_device_unbusy(device); + + /* + * Requeue this command. It will go before all other commands + * that are already in the queue. Schedule requeue work under + * lock such that the kblockd_schedule_work() call happens + * before blk_cleanup_queue() finishes. + */ + cmd->result = 0; + if (q->mq_ops) { + scsi_mq_requeue_cmd(cmd); + return; + } + spin_lock_irqsave(q->queue_lock, flags); + blk_requeue_request(q, cmd->request); + kblockd_schedule_work(&device->requeue_work); + spin_unlock_irqrestore(q->queue_lock, flags); +} + +/* + * 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. + */ +void scsi_queue_insert(struct scsi_cmnd *cmd, int reason) +{ + __scsi_queue_insert(cmd, reason, 1); +} +/** + * scsi_execute - insert request and wait for the result + * @sdev: scsi device + * @cmd: scsi command + * @data_direction: data direction + * @buffer: data buffer + * @bufflen: len of buffer + * @sense: optional sense buffer + * @timeout: request timeout in seconds + * @retries: number of times to retry request + * @flags: or into request flags; + * @resid: optional residual length + * + * returns the req->errors value which is the scsi_cmnd result + * field. + */ +int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd, + int data_direction, void *buffer, unsigned bufflen, + unsigned char *sense, int timeout, int retries, u64 flags, + int *resid) +{ + struct request *req; + int write = (data_direction == DMA_TO_DEVICE); + int ret = DRIVER_ERROR << 24; + + req = blk_get_request(sdev->request_queue, write, __GFP_WAIT); + if (IS_ERR(req)) + return ret; + blk_rq_set_block_pc(req); + + if (bufflen && blk_rq_map_kern(sdev->request_queue, req, + buffer, bufflen, __GFP_WAIT)) + goto out; + + req->cmd_len = COMMAND_SIZE(cmd[0]); + memcpy(req->cmd, cmd, req->cmd_len); + req->sense = sense; + req->sense_len = 0; + req->retries = retries; + req->timeout = timeout; + req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT; + + /* + * head injection *required* here otherwise quiesce won't work + */ + blk_execute_rq(req->q, NULL, req, 1); + + /* + * Some devices (USB mass-storage in particular) may transfer + * garbage data together with a residue indicating that the data + * is invalid. Prevent the garbage from being misinterpreted + * and prevent security leaks by zeroing out the excess data. + */ + if (unlikely(req->resid_len > 0 && req->resid_len <= bufflen)) + memset(buffer + (bufflen - req->resid_len), 0, req->resid_len); + + if (resid) + *resid = req->resid_len; + ret = req->errors; + out: + blk_put_request(req); + + return ret; +} +EXPORT_SYMBOL(scsi_execute); + +int scsi_execute_req_flags(struct scsi_device *sdev, const unsigned char *cmd, + int data_direction, void *buffer, unsigned bufflen, + struct scsi_sense_hdr *sshdr, int timeout, int retries, + int *resid, u64 flags) +{ + char *sense = NULL; + int result; + + if (sshdr) { + sense = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO); + if (!sense) + return DRIVER_ERROR << 24; + } + result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen, + sense, timeout, retries, flags, resid); + if (sshdr) + scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr); + + kfree(sense); + return result; +} +EXPORT_SYMBOL(scsi_execute_req_flags); + +/* + * Function: scsi_init_cmd_errh() + * + * Purpose: Initialize cmd fields related to error handling. + * + * Arguments: cmd - command that is ready to be queued. + * + * 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 void scsi_init_cmd_errh(struct scsi_cmnd *cmd) +{ + cmd->serial_number = 0; + scsi_set_resid(cmd, 0); + memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE); + if (cmd->cmd_len == 0) + cmd->cmd_len = scsi_command_size(cmd->cmnd); +} + +void scsi_device_unbusy(struct scsi_device *sdev) +{ + struct Scsi_Host *shost = sdev->host; + struct scsi_target *starget = scsi_target(sdev); + unsigned long flags; + + atomic_dec(&shost->host_busy); + if (starget->can_queue > 0) + atomic_dec(&starget->target_busy); + + if (unlikely(scsi_host_in_recovery(shost) && + (shost->host_failed || shost->host_eh_scheduled))) { + spin_lock_irqsave(shost->host_lock, flags); + scsi_eh_wakeup(shost); + spin_unlock_irqrestore(shost->host_lock, flags); + } + + atomic_dec(&sdev->device_busy); +} + +static void scsi_kick_queue(struct request_queue *q) +{ + if (q->mq_ops) + blk_mq_start_hw_queues(q); + else + blk_run_queue(q); +} + +/* + * 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; + struct scsi_target *starget = scsi_target(current_sdev); + unsigned long flags; + + spin_lock_irqsave(shost->host_lock, flags); + starget->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. + */ + scsi_kick_queue(current_sdev->request_queue); + + spin_lock_irqsave(shost->host_lock, flags); + if (starget->starget_sdev_user) + goto out; + list_for_each_entry_safe(sdev, tmp, &starget->devices, + same_target_siblings) { + if (sdev == current_sdev) + continue; + if (scsi_device_get(sdev)) + continue; + + spin_unlock_irqrestore(shost->host_lock, flags); + scsi_kick_queue(sdev->request_queue); + spin_lock_irqsave(shost->host_lock, flags); + + scsi_device_put(sdev); + } + out: + spin_unlock_irqrestore(shost->host_lock, flags); +} + +static inline bool scsi_device_is_busy(struct scsi_device *sdev) +{ + if (atomic_read(&sdev->device_busy) >= sdev->queue_depth) + return true; + if (atomic_read(&sdev->device_blocked) > 0) + return true; + return false; +} + +static inline bool scsi_target_is_busy(struct scsi_target *starget) +{ + if (starget->can_queue > 0) { + if (atomic_read(&starget->target_busy) >= starget->can_queue) + return true; + if (atomic_read(&starget->target_blocked) > 0) + return true; + } + return false; +} + +static inline bool scsi_host_is_busy(struct Scsi_Host *shost) +{ + if (shost->can_queue > 0 && + atomic_read(&shost->host_busy) >= shost->can_queue) + return true; + if (atomic_read(&shost->host_blocked) > 0) + return true; + if (shost->host_self_blocked) + return true; + return false; +} + +static void scsi_starved_list_run(struct Scsi_Host *shost) +{ + LIST_HEAD(starved_list); + struct scsi_device *sdev; + unsigned long flags; + + spin_lock_irqsave(shost->host_lock, flags); + list_splice_init(&shost->starved_list, &starved_list); + + while (!list_empty(&starved_list)) { + struct request_queue *slq; + + /* + * 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. + */ + if (scsi_host_is_busy(shost)) + break; + + sdev = list_entry(starved_list.next, + struct scsi_device, starved_entry); + list_del_init(&sdev->starved_entry); + if (scsi_target_is_busy(scsi_target(sdev))) { + list_move_tail(&sdev->starved_entry, + &shost->starved_list); + continue; + } + + /* + * Once we drop the host lock, a racing scsi_remove_device() + * call may remove the sdev from the starved list and destroy + * it and the queue. Mitigate by taking a reference to the + * queue and never touching the sdev again after we drop the + * host lock. Note: if __scsi_remove_device() invokes + * blk_cleanup_queue() before the queue is run from this + * function then blk_run_queue() will return immediately since + * blk_cleanup_queue() marks the queue with QUEUE_FLAG_DYING. + */ + slq = sdev->request_queue; + if (!blk_get_queue(slq)) + continue; + spin_unlock_irqrestore(shost->host_lock, flags); + + scsi_kick_queue(slq); + blk_put_queue(slq); + + spin_lock_irqsave(shost->host_lock, flags); + } + /* put any unprocessed entries back */ + list_splice(&starved_list, &shost->starved_list); + 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; + + if (scsi_target(sdev)->single_lun) + scsi_single_lun_run(sdev); + if (!list_empty(&sdev->host->starved_list)) + scsi_starved_list_run(sdev->host); + + if (q->mq_ops) + blk_mq_start_stopped_hw_queues(q, false); + else + blk_run_queue(q); +} + +void scsi_requeue_run_queue(struct work_struct *work) +{ + struct scsi_device *sdev; + struct request_queue *q; + + sdev = container_of(work, struct scsi_device, requeue_work); + q = sdev->request_queue; + scsi_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. + * Notes: Upon return, cmd is a stale pointer. + */ +static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd) +{ + struct scsi_device *sdev = cmd->device; + struct request *req = cmd->request; + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + blk_unprep_request(req); + req->special = NULL; + scsi_put_command(cmd); + blk_requeue_request(q, req); + spin_unlock_irqrestore(q->queue_lock, flags); + + scsi_run_queue(q); + + put_device(&sdev->sdev_gendev); +} + +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); +} + +static inline unsigned int scsi_sgtable_index(unsigned short nents) +{ + unsigned int index; + + BUG_ON(nents > SCSI_MAX_SG_SEGMENTS); + + if (nents <= 8) + index = 0; + else + index = get_count_order(nents) - 3; + + return index; +} + +static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents) +{ + struct scsi_host_sg_pool *sgp; + + sgp = scsi_sg_pools + scsi_sgtable_index(nents); + mempool_free(sgl, sgp->pool); +} + +static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask) +{ + struct scsi_host_sg_pool *sgp; + + sgp = scsi_sg_pools + scsi_sgtable_index(nents); + return mempool_alloc(sgp->pool, gfp_mask); +} + +static void scsi_free_sgtable(struct scsi_data_buffer *sdb, bool mq) +{ + if (mq && sdb->table.nents <= SCSI_MAX_SG_SEGMENTS) + return; + __sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, mq, scsi_sg_free); +} + +static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents, bool mq) +{ + struct scatterlist *first_chunk = NULL; + int ret; + + BUG_ON(!nents); + + if (mq) { + if (nents <= SCSI_MAX_SG_SEGMENTS) { + sdb->table.nents = nents; + sg_init_table(sdb->table.sgl, sdb->table.nents); + return 0; + } + first_chunk = sdb->table.sgl; + } + + ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS, + first_chunk, GFP_ATOMIC, scsi_sg_alloc); + if (unlikely(ret)) + scsi_free_sgtable(sdb, mq); + return ret; +} + +static void scsi_uninit_cmd(struct scsi_cmnd *cmd) +{ + if (cmd->request->cmd_type == REQ_TYPE_FS) { + struct scsi_driver *drv = scsi_cmd_to_driver(cmd); + + if (drv->uninit_command) + drv->uninit_command(cmd); + } +} + +static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd) +{ + if (cmd->sdb.table.nents) + scsi_free_sgtable(&cmd->sdb, true); + if (cmd->request->next_rq && cmd->request->next_rq->special) + scsi_free_sgtable(cmd->request->next_rq->special, true); + if (scsi_prot_sg_count(cmd)) + scsi_free_sgtable(cmd->prot_sdb, true); +} + +static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd) +{ + struct scsi_device *sdev = cmd->device; + struct Scsi_Host *shost = sdev->host; + unsigned long flags; + + scsi_mq_free_sgtables(cmd); + scsi_uninit_cmd(cmd); + + if (shost->use_cmd_list) { + BUG_ON(list_empty(&cmd->list)); + spin_lock_irqsave(&sdev->list_lock, flags); + list_del_init(&cmd->list); + spin_unlock_irqrestore(&sdev->list_lock, flags); + } +} + +/* + * Function: scsi_release_buffers() + * + * Purpose: Free resources allocate for a scsi_command. + * + * 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. + */ +static void scsi_release_buffers(struct scsi_cmnd *cmd) +{ + if (cmd->sdb.table.nents) + scsi_free_sgtable(&cmd->sdb, false); + + memset(&cmd->sdb, 0, sizeof(cmd->sdb)); + + if (scsi_prot_sg_count(cmd)) + scsi_free_sgtable(cmd->prot_sdb, false); +} + +static void scsi_release_bidi_buffers(struct scsi_cmnd *cmd) +{ + struct scsi_data_buffer *bidi_sdb = cmd->request->next_rq->special; + + scsi_free_sgtable(bidi_sdb, false); + kmem_cache_free(scsi_sdb_cache, bidi_sdb); + cmd->request->next_rq->special = NULL; +} + +static bool scsi_end_request(struct request *req, int error, + unsigned int bytes, unsigned int bidi_bytes) +{ + struct scsi_cmnd *cmd = req->special; + struct scsi_device *sdev = cmd->device; + struct request_queue *q = sdev->request_queue; + + if (blk_update_request(req, error, bytes)) + return true; + + /* Bidi request must be completed as a whole */ + if (unlikely(bidi_bytes) && + blk_update_request(req->next_rq, error, bidi_bytes)) + return true; + + if (blk_queue_add_random(q)) + add_disk_randomness(req->rq_disk); + + if (req->mq_ctx) { + /* + * In the MQ case the command gets freed by __blk_mq_end_request, + * so we have to do all cleanup that depends on it earlier. + * + * We also can't kick the queues from irq context, so we + * will have to defer it to a workqueue. + */ + scsi_mq_uninit_cmd(cmd); + + __blk_mq_end_request(req, error); + + if (scsi_target(sdev)->single_lun || + !list_empty(&sdev->host->starved_list)) + kblockd_schedule_work(&sdev->requeue_work); + else + blk_mq_start_stopped_hw_queues(q, true); + } else { + unsigned long flags; + + if (bidi_bytes) + scsi_release_bidi_buffers(cmd); + + spin_lock_irqsave(q->queue_lock, flags); + blk_finish_request(req, error); + spin_unlock_irqrestore(q->queue_lock, flags); + + scsi_release_buffers(cmd); + + scsi_put_command(cmd); + scsi_run_queue(q); + } + + put_device(&sdev->sdev_gendev); + return false; +} + +/** + * __scsi_error_from_host_byte - translate SCSI error code into errno + * @cmd: SCSI command (unused) + * @result: scsi error code + * + * Translate SCSI error code into standard UNIX errno. + * Return values: + * -ENOLINK temporary transport failure + * -EREMOTEIO permanent target failure, do not retry + * -EBADE permanent nexus failure, retry on other path + * -ENOSPC No write space available + * -ENODATA Medium error + * -EIO unspecified I/O error + */ +static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result) +{ + int error = 0; + + switch(host_byte(result)) { + case DID_TRANSPORT_FAILFAST: + error = -ENOLINK; + break; + case DID_TARGET_FAILURE: + set_host_byte(cmd, DID_OK); + error = -EREMOTEIO; + break; + case DID_NEXUS_FAILURE: + set_host_byte(cmd, DID_OK); + error = -EBADE; + break; + case DID_ALLOC_FAILURE: + set_host_byte(cmd, DID_OK); + error = -ENOSPC; + break; + case DID_MEDIUM_ERROR: + set_host_byte(cmd, DID_OK); + error = -ENODATA; + break; + default: + error = -EIO; + break; + } + + return error; +} + +/* + * 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: We 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 we have to + * figure out what to do next: + * + * a) We can call scsi_requeue_command(). The request + * will be unprepared and put back on the queue. Then + * a new command will be created for it. This should + * be used if we made forward progress, or if we want + * to switch from READ(10) to READ(6) for example. + * + * b) We can call __scsi_queue_insert(). The request will + * be put back on the queue and retried using the same + * command as before, possibly after a delay. + * + * c) We can call scsi_end_request() with -EIO to fail + * the remainder of the request. + */ +void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes) +{ + int result = cmd->result; + struct request_queue *q = cmd->device->request_queue; + struct request *req = cmd->request; + int error = 0; + struct scsi_sense_hdr sshdr; + bool sense_valid = false; + int sense_deferred = 0, level = 0; + enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY, + ACTION_DELAYED_RETRY} action; + unsigned long wait_for = (cmd->allowed + 1) * req->timeout; + + if (result) { + sense_valid = scsi_command_normalize_sense(cmd, &sshdr); + if (sense_valid) + sense_deferred = scsi_sense_is_deferred(&sshdr); + } + + if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */ + if (result) { + if (sense_valid && req->sense) { + /* + * SG_IO wants current and deferred errors + */ + 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; + } + if (!sense_deferred) + error = __scsi_error_from_host_byte(cmd, result); + } + /* + * __scsi_error_from_host_byte may have reset the host_byte + */ + req->errors = cmd->result; + + req->resid_len = scsi_get_resid(cmd); + + if (scsi_bidi_cmnd(cmd)) { + /* + * Bidi commands Must be complete as a whole, + * both sides at once. + */ + req->next_rq->resid_len = scsi_in(cmd)->resid; + if (scsi_end_request(req, 0, blk_rq_bytes(req), + blk_rq_bytes(req->next_rq))) + BUG(); + return; + } + } else if (blk_rq_bytes(req) == 0 && result && !sense_deferred) { + /* + * Certain non BLOCK_PC requests are commands that don't + * actually transfer anything (FLUSH), so cannot use + * good_bytes != blk_rq_bytes(req) as the signal for an error. + * This sets the error explicitly for the problem case. + */ + error = __scsi_error_from_host_byte(cmd, result); + } + + /* no bidi support for !REQ_TYPE_BLOCK_PC yet */ + BUG_ON(blk_bidi_rq(req)); + + /* + * Next deal with any sectors which we were able to correctly + * handle. + */ + SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd, + "%u sectors total, %d bytes done.\n", + blk_rq_sectors(req), good_bytes)); + + /* + * Recovered errors need reporting, but they're always treated + * as success, so fiddle the result code here. For BLOCK_PC + * we already took a copy of the original into rq->errors which + * is what gets returned to the user + */ + if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) { + /* if ATA PASS-THROUGH INFORMATION AVAILABLE skip + * print since caller wants ATA registers. Only occurs on + * SCSI ATA PASS_THROUGH commands when CK_COND=1 + */ + if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d)) + ; + else if (!(req->cmd_flags & REQ_QUIET)) + scsi_print_sense(cmd); + result = 0; + /* BLOCK_PC may have set error */ + error = 0; + } + + /* + * If we finished all bytes in the request we are done now. + */ + if (!scsi_end_request(req, error, good_bytes, 0)) + return; + + /* + * Kill remainder if no retrys. + */ + if (error && scsi_noretry_cmd(cmd)) { + if (scsi_end_request(req, error, blk_rq_bytes(req), 0)) + BUG(); + return; + } + + /* + * If there had been no error, but we have leftover bytes in the + * requeues just queue the command up again. + */ + if (result == 0) + goto requeue; + + error = __scsi_error_from_host_byte(cmd, result); + + if (host_byte(result) == DID_RESET) { + /* Third party bus reset or reset for error recovery + * reasons. Just retry the command and see what + * happens. + */ + action = ACTION_RETRY; + } else if (sense_valid && !sense_deferred) { + switch (sshdr.sense_key) { + case UNIT_ATTENTION: + if (cmd->device->removable) { + /* Detected disc change. Set a bit + * and quietly refuse further access. + */ + cmd->device->changed = 1; + action = ACTION_FAIL; + } else { + /* Must have been a power glitch, or a + * bus reset. Could not have been a + * media change, so we just retry the + * command and see what happens. + */ + action = ACTION_RETRY; + } + break; + case ILLEGAL_REQUEST: + /* 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. + */ + if ((cmd->device->use_10_for_rw && + sshdr.asc == 0x20 && sshdr.ascq == 0x00) && + (cmd->cmnd[0] == READ_10 || + cmd->cmnd[0] == WRITE_10)) { + /* This will issue a new 6-byte command. */ + cmd->device->use_10_for_rw = 0; + action = ACTION_REPREP; + } else if (sshdr.asc == 0x10) /* DIX */ { + action = ACTION_FAIL; + error = -EILSEQ; + /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */ + } else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) { + action = ACTION_FAIL; + error = -EREMOTEIO; + } else + action = ACTION_FAIL; + break; + case ABORTED_COMMAND: + action = ACTION_FAIL; + if (sshdr.asc == 0x10) /* DIF */ + error = -EILSEQ; + break; + case NOT_READY: + /* If the device is in the process of becoming + * ready, or has a temporary blockage, retry. + */ + if (sshdr.asc == 0x04) { + switch (sshdr.ascq) { + case 0x01: /* becoming ready */ + case 0x04: /* format in progress */ + case 0x05: /* rebuild in progress */ + case 0x06: /* recalculation in progress */ + case 0x07: /* operation in progress */ + case 0x08: /* Long write in progress */ + case 0x09: /* self test in progress */ + case 0x14: /* space allocation in progress */ + action = ACTION_DELAYED_RETRY; + break; + default: + action = ACTION_FAIL; + break; + } + } else + action = ACTION_FAIL; + break; + case VOLUME_OVERFLOW: + /* See SSC3rXX or current. */ + action = ACTION_FAIL; + break; + default: + action = ACTION_FAIL; + break; + } + } else + action = ACTION_FAIL; + + if (action != ACTION_FAIL && + time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) + action = ACTION_FAIL; + + switch (action) { + case ACTION_FAIL: + /* Give up and fail the remainder of the request */ + if (!(req->cmd_flags & REQ_QUIET)) { + static DEFINE_RATELIMIT_STATE(_rs, + DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); + + if (unlikely(scsi_logging_level)) + level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT, + SCSI_LOG_MLCOMPLETE_BITS); + + /* + * if logging is enabled the failure will be printed + * in scsi_log_completion(), so avoid duplicate messages + */ + if (!level && __ratelimit(&_rs)) { + scsi_print_result(cmd, NULL, FAILED); + if (driver_byte(result) & DRIVER_SENSE) + scsi_print_sense(cmd); + scsi_print_command(cmd); + } + } + if (!scsi_end_request(req, error, blk_rq_err_bytes(req), 0)) + return; + /*FALLTHRU*/ + case ACTION_REPREP: + requeue: + /* Unprep the request and put it back at the head of the queue. + * A new command will be prepared and issued. + */ + if (q->mq_ops) { + cmd->request->cmd_flags &= ~REQ_DONTPREP; + scsi_mq_uninit_cmd(cmd); + scsi_mq_requeue_cmd(cmd); + } else { + scsi_release_buffers(cmd); + scsi_requeue_command(q, cmd); + } + break; + case ACTION_RETRY: + /* Retry the same command immediately */ + __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0); + break; + case ACTION_DELAYED_RETRY: + /* Retry the same command after a delay */ + __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0); + break; + } +} + +static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb) +{ + int count; + + /* + * If sg table allocation fails, requeue request later. + */ + if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments, + req->mq_ctx != NULL))) + return BLKPREP_DEFER; + + /* + * Next, walk the list, and fill in the addresses and sizes of + * each segment. + */ + count = blk_rq_map_sg(req->q, req, sdb->table.sgl); + BUG_ON(count > sdb->table.nents); + sdb->table.nents = count; + sdb->length = blk_rq_bytes(req); + return BLKPREP_OK; +} + +/* + * 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 + */ +int scsi_init_io(struct scsi_cmnd *cmd) +{ + struct scsi_device *sdev = cmd->device; + struct request *rq = cmd->request; + bool is_mq = (rq->mq_ctx != NULL); + int error; + + BUG_ON(!rq->nr_phys_segments); + + error = scsi_init_sgtable(rq, &cmd->sdb); + if (error) + goto err_exit; + + if (blk_bidi_rq(rq)) { + if (!rq->q->mq_ops) { + struct scsi_data_buffer *bidi_sdb = + kmem_cache_zalloc(scsi_sdb_cache, GFP_ATOMIC); + if (!bidi_sdb) { + error = BLKPREP_DEFER; + goto err_exit; + } + + rq->next_rq->special = bidi_sdb; + } + + error = scsi_init_sgtable(rq->next_rq, rq->next_rq->special); + if (error) + goto err_exit; + } + + if (blk_integrity_rq(rq)) { + struct scsi_data_buffer *prot_sdb = cmd->prot_sdb; + int ivecs, count; + + if (prot_sdb == NULL) { + /* + * This can happen if someone (e.g. multipath) + * queues a command to a device on an adapter + * that does not support DIX. + */ + WARN_ON_ONCE(1); + error = BLKPREP_KILL; + goto err_exit; + } + + ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio); + + if (scsi_alloc_sgtable(prot_sdb, ivecs, is_mq)) { + error = BLKPREP_DEFER; + goto err_exit; + } + + count = blk_rq_map_integrity_sg(rq->q, rq->bio, + prot_sdb->table.sgl); + BUG_ON(unlikely(count > ivecs)); + BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q))); + + cmd->prot_sdb = prot_sdb; + cmd->prot_sdb->table.nents = count; + } + + return BLKPREP_OK; +err_exit: + if (is_mq) { + scsi_mq_free_sgtables(cmd); + } else { + scsi_release_buffers(cmd); + cmd->request->special = NULL; + scsi_put_command(cmd); + put_device(&sdev->sdev_gendev); + } + return error; +} +EXPORT_SYMBOL(scsi_init_io); + +static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev, + struct request *req) +{ + struct scsi_cmnd *cmd; + + if (!req->special) { + /* Bail if we can't get a reference to the device */ + if (!get_device(&sdev->sdev_gendev)) + return NULL; + + cmd = scsi_get_command(sdev, GFP_ATOMIC); + if (unlikely(!cmd)) { + put_device(&sdev->sdev_gendev); + return NULL; + } + req->special = cmd; + } else { + cmd = req->special; + } + + /* pull a tag out of the request if we have one */ + cmd->tag = req->tag; + cmd->request = req; + + cmd->cmnd = req->cmd; + cmd->prot_op = SCSI_PROT_NORMAL; + + return cmd; +} + +static int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req) +{ + struct scsi_cmnd *cmd = req->special; + + /* + * BLOCK_PC requests may transfer data, in which case they must + * a bio attached to them. Or they might contain a SCSI command + * that does not transfer data, in which case they may optionally + * submit a request without an attached bio. + */ + if (req->bio) { + int ret = scsi_init_io(cmd); + if (unlikely(ret)) + return ret; + } else { + BUG_ON(blk_rq_bytes(req)); + + memset(&cmd->sdb, 0, sizeof(cmd->sdb)); + } + + cmd->cmd_len = req->cmd_len; + cmd->transfersize = blk_rq_bytes(req); + cmd->allowed = req->retries; + return BLKPREP_OK; +} + +/* + * Setup a REQ_TYPE_FS command. These are simple request from filesystems + * that still need to be translated to SCSI CDBs from the ULD. + */ +static int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req) +{ + struct scsi_cmnd *cmd = req->special; + + if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh + && sdev->scsi_dh_data->scsi_dh->prep_fn)) { + int ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req); + if (ret != BLKPREP_OK) + return ret; + } + + memset(cmd->cmnd, 0, BLK_MAX_CDB); + return scsi_cmd_to_driver(cmd)->init_command(cmd); +} + +static int scsi_setup_cmnd(struct scsi_device *sdev, struct request *req) +{ + struct scsi_cmnd *cmd = req->special; + + if (!blk_rq_bytes(req)) + cmd->sc_data_direction = DMA_NONE; + else if (rq_data_dir(req) == WRITE) + cmd->sc_data_direction = DMA_TO_DEVICE; + else + cmd->sc_data_direction = DMA_FROM_DEVICE; + + switch (req->cmd_type) { + case REQ_TYPE_FS: + return scsi_setup_fs_cmnd(sdev, req); + case REQ_TYPE_BLOCK_PC: + return scsi_setup_blk_pc_cmnd(sdev, req); + default: + return BLKPREP_KILL; + } +} + +static int +scsi_prep_state_check(struct scsi_device *sdev, struct request *req) +{ + int ret = BLKPREP_OK; + + /* + * If the device is not in running state we will reject some + * or all commands. + */ + if (unlikely(sdev->sdev_state != SDEV_RUNNING)) { + switch (sdev->sdev_state) { + case SDEV_OFFLINE: + case SDEV_TRANSPORT_OFFLINE: + /* + * If the device is offline we refuse to process any + * commands. The device must be brought online + * before trying any recovery commands. + */ + sdev_printk(KERN_ERR, sdev, + "rejecting I/O to offline device\n"); + ret = BLKPREP_KILL; + break; + case SDEV_DEL: + /* + * If the device is fully deleted, we refuse to + * process any commands as well. + */ + sdev_printk(KERN_ERR, sdev, + "rejecting I/O to dead device\n"); + ret = BLKPREP_KILL; + break; + case SDEV_BLOCK: + case SDEV_CREATED_BLOCK: + ret = BLKPREP_DEFER; + break; + case SDEV_QUIESCE: + /* + * If the devices is blocked we defer normal commands. + */ + if (!(req->cmd_flags & REQ_PREEMPT)) + ret = BLKPREP_DEFER; + break; + default: + /* + * For any other not fully online state we only allow + * special commands. In particular any user initiated + * command is not allowed. + */ + if (!(req->cmd_flags & REQ_PREEMPT)) + ret = BLKPREP_KILL; + break; + } + } + return ret; +} + +static int +scsi_prep_return(struct request_queue *q, struct request *req, int ret) +{ + struct scsi_device *sdev = q->queuedata; + + switch (ret) { + case BLKPREP_KILL: + req->errors = DID_NO_CONNECT << 16; + /* release the command and kill it */ + if (req->special) { + struct scsi_cmnd *cmd = req->special; + scsi_release_buffers(cmd); + scsi_put_command(cmd); + put_device(&sdev->sdev_gendev); + req->special = NULL; + } + break; + case BLKPREP_DEFER: + /* + * If we defer, the blk_peek_request() returns NULL, but the + * queue must be restarted, so we schedule a callback to happen + * shortly. + */ + if (atomic_read(&sdev->device_busy) == 0) + blk_delay_queue(q, SCSI_QUEUE_DELAY); + break; + default: + req->cmd_flags |= REQ_DONTPREP; + } + + return ret; +} + +static int scsi_prep_fn(struct request_queue *q, struct request *req) +{ + struct scsi_device *sdev = q->queuedata; + struct scsi_cmnd *cmd; + int ret; + + ret = scsi_prep_state_check(sdev, req); + if (ret != BLKPREP_OK) + goto out; + + cmd = scsi_get_cmd_from_req(sdev, req); + if (unlikely(!cmd)) { + ret = BLKPREP_DEFER; + goto out; + } + + ret = scsi_setup_cmnd(sdev, req); +out: + return scsi_prep_return(q, req, ret); +} + +static void scsi_unprep_fn(struct request_queue *q, struct request *req) +{ + scsi_uninit_cmd(req->special); +} + +/* + * 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) +{ + unsigned int busy; + + busy = atomic_inc_return(&sdev->device_busy) - 1; + if (atomic_read(&sdev->device_blocked)) { + if (busy) + goto out_dec; + + /* + * unblock after device_blocked iterates to zero + */ + if (atomic_dec_return(&sdev->device_blocked) > 0) { + /* + * For the MQ case we take care of this in the caller. + */ + if (!q->mq_ops) + blk_delay_queue(q, SCSI_QUEUE_DELAY); + goto out_dec; + } + SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev, + "unblocking device at zero depth\n")); + } + + if (busy >= sdev->queue_depth) + goto out_dec; + + return 1; +out_dec: + atomic_dec(&sdev->device_busy); + return 0; +} + +/* + * scsi_target_queue_ready: checks if there we can send commands to target + * @sdev: scsi device on starget to check. + */ +static inline int scsi_target_queue_ready(struct Scsi_Host *shost, + struct scsi_device *sdev) +{ + struct scsi_target *starget = scsi_target(sdev); + unsigned int busy; + + if (starget->single_lun) { + spin_lock_irq(shost->host_lock); + if (starget->starget_sdev_user && + starget->starget_sdev_user != sdev) { + spin_unlock_irq(shost->host_lock); + return 0; + } + starget->starget_sdev_user = sdev; + spin_unlock_irq(shost->host_lock); + } + + if (starget->can_queue <= 0) + return 1; + + busy = atomic_inc_return(&starget->target_busy) - 1; + if (atomic_read(&starget->target_blocked) > 0) { + if (busy) + goto starved; + + /* + * unblock after target_blocked iterates to zero + */ + if (atomic_dec_return(&starget->target_blocked) > 0) + goto out_dec; + + SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget, + "unblocking target at zero depth\n")); + } + + if (busy >= starget->can_queue) + goto starved; + + return 1; + +starved: + spin_lock_irq(shost->host_lock); + list_move_tail(&sdev->starved_entry, &shost->starved_list); + spin_unlock_irq(shost->host_lock); +out_dec: + if (starget->can_queue > 0) + atomic_dec(&starget->target_busy); + return 0; +} + +/* + * 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. + */ +static inline int scsi_host_queue_ready(struct request_queue *q, + struct Scsi_Host *shost, + struct scsi_device *sdev) +{ + unsigned int busy; + + if (scsi_host_in_recovery(shost)) + return 0; + + busy = atomic_inc_return(&shost->host_busy) - 1; + if (atomic_read(&shost->host_blocked) > 0) { + if (busy) + goto starved; + + /* + * unblock after host_blocked iterates to zero + */ + if (atomic_dec_return(&shost->host_blocked) > 0) + goto out_dec; + + SCSI_LOG_MLQUEUE(3, + shost_printk(KERN_INFO, shost, + "unblocking host at zero depth\n")); + } + + if (shost->can_queue > 0 && busy >= shost->can_queue) + goto starved; + if (shost->host_self_blocked) + goto starved; + + /* We're OK to process the command, so we can't be starved */ + if (!list_empty(&sdev->starved_entry)) { + spin_lock_irq(shost->host_lock); + if (!list_empty(&sdev->starved_entry)) + list_del_init(&sdev->starved_entry); + spin_unlock_irq(shost->host_lock); + } + + return 1; + +starved: + spin_lock_irq(shost->host_lock); + if (list_empty(&sdev->starved_entry)) + list_add_tail(&sdev->starved_entry, &shost->starved_list); + spin_unlock_irq(shost->host_lock); +out_dec: + atomic_dec(&shost->host_busy); + return 0; +} + +/* + * Busy state exporting function for request stacking drivers. + * + * For efficiency, no lock is taken to check the busy state of + * shost/starget/sdev, since the returned value is not guaranteed and + * may be changed after request stacking drivers call the function, + * regardless of taking lock or not. + * + * When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi + * needs to return 'not busy'. Otherwise, request stacking drivers + * may hold requests forever. + */ +static int scsi_lld_busy(struct request_queue *q) +{ + struct scsi_device *sdev = q->queuedata; + struct Scsi_Host *shost; + + if (blk_queue_dying(q)) + return 0; + + shost = sdev->host; + + /* + * Ignore host/starget busy state. + * Since block layer does not have a concept of fairness across + * multiple queues, congestion of host/starget needs to be handled + * in SCSI layer. + */ + if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev)) + return 1; + + return 0; +} + +/* + * Kill a request for a dead device + */ +static void scsi_kill_request(struct request *req, struct request_queue *q) +{ + struct scsi_cmnd *cmd = req->special; + struct scsi_device *sdev; + struct scsi_target *starget; + struct Scsi_Host *shost; + + blk_start_request(req); + + scmd_printk(KERN_INFO, cmd, "killing request\n"); + + sdev = cmd->device; + starget = scsi_target(sdev); + shost = sdev->host; + scsi_init_cmd_errh(cmd); + cmd->result = DID_NO_CONNECT << 16; + atomic_inc(&cmd->device->iorequest_cnt); + + /* + * SCSI request completion path will do scsi_device_unbusy(), + * bump busy counts. To bump the counters, we need to dance + * with the locks as normal issue path does. + */ + atomic_inc(&sdev->device_busy); + atomic_inc(&shost->host_busy); + if (starget->can_queue > 0) + atomic_inc(&starget->target_busy); + + blk_complete_request(req); +} + +static void scsi_softirq_done(struct request *rq) +{ + struct scsi_cmnd *cmd = rq->special; + unsigned long wait_for = (cmd->allowed + 1) * rq->timeout; + int disposition; + + INIT_LIST_HEAD(&cmd->eh_entry); + + atomic_inc(&cmd->device->iodone_cnt); + if (cmd->result) + atomic_inc(&cmd->device->ioerr_cnt); + + disposition = scsi_decide_disposition(cmd); + if (disposition != SUCCESS && + time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) { + sdev_printk(KERN_ERR, cmd->device, + "timing out command, waited %lus\n", + wait_for/HZ); + disposition = SUCCESS; + } + + scsi_log_completion(cmd, disposition); + + switch (disposition) { + case SUCCESS: + scsi_finish_command(cmd); + break; + case NEEDS_RETRY: + scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY); + break; + case ADD_TO_MLQUEUE: + scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY); + break; + default: + if (!scsi_eh_scmd_add(cmd, 0)) + scsi_finish_command(cmd); + } +} + +/** + * scsi_dispatch_command - Dispatch a command to the low-level driver. + * @cmd: command block we are dispatching. + * + * Return: nonzero return request was rejected and device's queue needs to be + * plugged. + */ +static int scsi_dispatch_cmd(struct scsi_cmnd *cmd) +{ + struct Scsi_Host *host = cmd->device->host; + int rtn = 0; + + atomic_inc(&cmd->device->iorequest_cnt); + + /* check if the device is still usable */ + if (unlikely(cmd->device->sdev_state == SDEV_DEL)) { + /* in SDEV_DEL we error all commands. DID_NO_CONNECT + * returns an immediate error upwards, and signals + * that the device is no longer present */ + cmd->result = DID_NO_CONNECT << 16; + goto done; + } + + /* Check to see if the scsi lld made this device blocked. */ + if (unlikely(scsi_device_blocked(cmd->device))) { + /* + * in blocked state, the command is just put back on + * the device queue. The suspend state has already + * blocked the queue so future requests should not + * occur until the device transitions out of the + * suspend state. + */ + SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd, + "queuecommand : device blocked\n")); + return SCSI_MLQUEUE_DEVICE_BUSY; + } + + /* Store the LUN value in cmnd, if needed. */ + if (cmd->device->lun_in_cdb) + cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) | + (cmd->device->lun << 5 & 0xe0); + + scsi_log_send(cmd); + + /* + * Before we queue this command, check if the command + * length exceeds what the host adapter can handle. + */ + if (cmd->cmd_len > cmd->device->host->max_cmd_len) { + SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd, + "queuecommand : command too long. " + "cdb_size=%d host->max_cmd_len=%d\n", + cmd->cmd_len, cmd->device->host->max_cmd_len)); + cmd->result = (DID_ABORT << 16); + goto done; + } + + if (unlikely(host->shost_state == SHOST_DEL)) { + cmd->result = (DID_NO_CONNECT << 16); + goto done; + + } + + trace_scsi_dispatch_cmd_start(cmd); + rtn = host->hostt->queuecommand(host, cmd); + if (rtn) { + trace_scsi_dispatch_cmd_error(cmd, rtn); + if (rtn != SCSI_MLQUEUE_DEVICE_BUSY && + rtn != SCSI_MLQUEUE_TARGET_BUSY) + rtn = SCSI_MLQUEUE_HOST_BUSY; + + SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd, + "queuecommand : request rejected\n")); + } + + return rtn; + done: + cmd->scsi_done(cmd); + return 0; +} + +/** + * scsi_done - Invoke completion on finished SCSI command. + * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives + * ownership back to SCSI Core -- i.e. the LLDD has finished with it. + * + * Description: This function is the mid-level's (SCSI Core) interrupt routine, + * which regains ownership of the SCSI command (de facto) from a LLDD, and + * calls blk_complete_request() for further processing. + * + * This function is interrupt context safe. + */ +static void scsi_done(struct scsi_cmnd *cmd) +{ + trace_scsi_dispatch_cmd_done(cmd); + blk_complete_request(cmd->request); +} + +/* + * 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) + __releases(q->queue_lock) + __acquires(q->queue_lock) +{ + struct scsi_device *sdev = q->queuedata; + struct Scsi_Host *shost; + struct scsi_cmnd *cmd; + struct request *req; + + /* + * To start with, we keep looping until the queue is empty, or until + * the host is no longer able to accept any more requests. + */ + shost = sdev->host; + for (;;) { + 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 = blk_peek_request(q); + if (!req) + break; + + if (unlikely(!scsi_device_online(sdev))) { + sdev_printk(KERN_ERR, sdev, + "rejecting I/O to offline device\n"); + scsi_kill_request(req, q); + continue; + } + + if (!scsi_dev_queue_ready(q, sdev)) + break; + + /* + * Remove the request from the request list. + */ + if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req))) + blk_start_request(req); + + spin_unlock_irq(q->queue_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\n", + __func__); + blk_dump_rq_flags(req, "foo"); + BUG(); + } + + /* + * We hit this when the driver is using a host wide + * tag map. For device level tag maps the queue_depth check + * in the device ready fn would prevent us from trying + * to allocate a tag. Since the map is a shared host resource + * we add the dev to the starved list so it eventually gets + * a run when a tag is freed. + */ + if (blk_queue_tagged(q) && !(req->cmd_flags & REQ_QUEUED)) { + spin_lock_irq(shost->host_lock); + if (list_empty(&sdev->starved_entry)) + list_add_tail(&sdev->starved_entry, + &shost->starved_list); + spin_unlock_irq(shost->host_lock); + goto not_ready; + } + + if (!scsi_target_queue_ready(shost, sdev)) + goto not_ready; + + if (!scsi_host_queue_ready(q, shost, sdev)) + goto host_not_ready; + + if (sdev->simple_tags) + cmd->flags |= SCMD_TAGGED; + else + cmd->flags &= ~SCMD_TAGGED; + + /* + * 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. + */ + cmd->scsi_done = scsi_done; + rtn = scsi_dispatch_cmd(cmd); + if (rtn) { + scsi_queue_insert(cmd, rtn); + spin_lock_irq(q->queue_lock); + goto out_delay; + } + spin_lock_irq(q->queue_lock); + } + + return; + + host_not_ready: + if (scsi_target(sdev)->can_queue > 0) + atomic_dec(&scsi_target(sdev)->target_busy); + not_ready: + /* + * 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); + atomic_dec(&sdev->device_busy); +out_delay: + if (!atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev)) + blk_delay_queue(q, SCSI_QUEUE_DELAY); +} + +static inline int prep_to_mq(int ret) +{ + switch (ret) { + case BLKPREP_OK: + return 0; + case BLKPREP_DEFER: + return BLK_MQ_RQ_QUEUE_BUSY; + default: + return BLK_MQ_RQ_QUEUE_ERROR; + } +} + +static int scsi_mq_prep_fn(struct request *req) +{ + struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req); + struct scsi_device *sdev = req->q->queuedata; + struct Scsi_Host *shost = sdev->host; + unsigned char *sense_buf = cmd->sense_buffer; + struct scatterlist *sg; + + memset(cmd, 0, sizeof(struct scsi_cmnd)); + + req->special = cmd; + + cmd->request = req; + cmd->device = sdev; + cmd->sense_buffer = sense_buf; + + cmd->tag = req->tag; + + cmd->cmnd = req->cmd; + cmd->prot_op = SCSI_PROT_NORMAL; + + INIT_LIST_HEAD(&cmd->list); + INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler); + cmd->jiffies_at_alloc = jiffies; + + if (shost->use_cmd_list) { + spin_lock_irq(&sdev->list_lock); + list_add_tail(&cmd->list, &sdev->cmd_list); + spin_unlock_irq(&sdev->list_lock); + } + + sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size; + cmd->sdb.table.sgl = sg; + + if (scsi_host_get_prot(shost)) { + cmd->prot_sdb = (void *)sg + + min_t(unsigned int, + shost->sg_tablesize, SCSI_MAX_SG_SEGMENTS) * + sizeof(struct scatterlist); + memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer)); + + cmd->prot_sdb->table.sgl = + (struct scatterlist *)(cmd->prot_sdb + 1); + } + + if (blk_bidi_rq(req)) { + struct request *next_rq = req->next_rq; + struct scsi_data_buffer *bidi_sdb = blk_mq_rq_to_pdu(next_rq); + + memset(bidi_sdb, 0, sizeof(struct scsi_data_buffer)); + bidi_sdb->table.sgl = + (struct scatterlist *)(bidi_sdb + 1); + + next_rq->special = bidi_sdb; + } + + blk_mq_start_request(req); + + return scsi_setup_cmnd(sdev, req); +} + +static void scsi_mq_done(struct scsi_cmnd *cmd) +{ + trace_scsi_dispatch_cmd_done(cmd); + blk_mq_complete_request(cmd->request); +} + +static int scsi_queue_rq(struct blk_mq_hw_ctx *hctx, + const struct blk_mq_queue_data *bd) +{ + struct request *req = bd->rq; + struct request_queue *q = req->q; + struct scsi_device *sdev = q->queuedata; + struct Scsi_Host *shost = sdev->host; + struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req); + int ret; + int reason; + + ret = prep_to_mq(scsi_prep_state_check(sdev, req)); + if (ret) + goto out; + + ret = BLK_MQ_RQ_QUEUE_BUSY; + if (!get_device(&sdev->sdev_gendev)) + goto out; + + if (!scsi_dev_queue_ready(q, sdev)) + goto out_put_device; + if (!scsi_target_queue_ready(shost, sdev)) + goto out_dec_device_busy; + if (!scsi_host_queue_ready(q, shost, sdev)) + goto out_dec_target_busy; + + + if (!(req->cmd_flags & REQ_DONTPREP)) { + ret = prep_to_mq(scsi_mq_prep_fn(req)); + if (ret) + goto out_dec_host_busy; + req->cmd_flags |= REQ_DONTPREP; + } else { + blk_mq_start_request(req); + } + + if (sdev->simple_tags) + cmd->flags |= SCMD_TAGGED; + else + cmd->flags &= ~SCMD_TAGGED; + + scsi_init_cmd_errh(cmd); + cmd->scsi_done = scsi_mq_done; + + reason = scsi_dispatch_cmd(cmd); + if (reason) { + scsi_set_blocked(cmd, reason); + ret = BLK_MQ_RQ_QUEUE_BUSY; + goto out_dec_host_busy; + } + + return BLK_MQ_RQ_QUEUE_OK; + +out_dec_host_busy: + atomic_dec(&shost->host_busy); +out_dec_target_busy: + if (scsi_target(sdev)->can_queue > 0) + atomic_dec(&scsi_target(sdev)->target_busy); +out_dec_device_busy: + atomic_dec(&sdev->device_busy); +out_put_device: + put_device(&sdev->sdev_gendev); +out: + switch (ret) { + case BLK_MQ_RQ_QUEUE_BUSY: + blk_mq_stop_hw_queue(hctx); + if (atomic_read(&sdev->device_busy) == 0 && + !scsi_device_blocked(sdev)) + blk_mq_delay_queue(hctx, SCSI_QUEUE_DELAY); + break; + case BLK_MQ_RQ_QUEUE_ERROR: + /* + * Make sure to release all allocated ressources when + * we hit an error, as we will never see this command + * again. + */ + if (req->cmd_flags & REQ_DONTPREP) + scsi_mq_uninit_cmd(cmd); + break; + default: + break; + } + return ret; +} + +static enum blk_eh_timer_return scsi_timeout(struct request *req, + bool reserved) +{ + if (reserved) + return BLK_EH_RESET_TIMER; + return scsi_times_out(req); +} + +static int scsi_init_request(void *data, struct request *rq, + unsigned int hctx_idx, unsigned int request_idx, + unsigned int numa_node) +{ + struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); + + cmd->sense_buffer = kzalloc_node(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL, + numa_node); + if (!cmd->sense_buffer) + return -ENOMEM; + return 0; +} + +static void scsi_exit_request(void *data, struct request *rq, + unsigned int hctx_idx, unsigned int request_idx) +{ + struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq); + + kfree(cmd->sense_buffer); +} + +static u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost) +{ + struct device *host_dev; + u64 bounce_limit = 0xffffffff; + + if (shost->unchecked_isa_dma) + return BLK_BOUNCE_ISA; + /* + * Platforms with virtual-DMA translation + * hardware have no practical limit. + */ + if (!PCI_DMA_BUS_IS_PHYS) + return BLK_BOUNCE_ANY; + + host_dev = scsi_get_device(shost); + if (host_dev && host_dev->dma_mask) + bounce_limit = (u64)dma_max_pfn(host_dev) << PAGE_SHIFT; + + return bounce_limit; +} + +static void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q) +{ + struct device *dev = shost->dma_dev; + + /* + * this limit is imposed by hardware restrictions + */ + blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize, + SCSI_MAX_SG_CHAIN_SEGMENTS)); + + if (scsi_host_prot_dma(shost)) { + shost->sg_prot_tablesize = + min_not_zero(shost->sg_prot_tablesize, + (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS); + BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize); + blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize); + } + + blk_queue_max_hw_sectors(q, shost->max_sectors); + blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost)); + blk_queue_segment_boundary(q, shost->dma_boundary); + dma_set_seg_boundary(dev, shost->dma_boundary); + + blk_queue_max_segment_size(q, dma_get_max_seg_size(dev)); + + if (!shost->use_clustering) + q->limits.cluster = 0; + + /* + * set a reasonable default alignment on word boundaries: the + * host and device may alter it using + * blk_queue_update_dma_alignment() later. + */ + blk_queue_dma_alignment(q, 0x03); +} + +struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost, + request_fn_proc *request_fn) +{ + struct request_queue *q; + + q = blk_init_queue(request_fn, NULL); + if (!q) + return NULL; + __scsi_init_queue(shost, q); + return q; +} +EXPORT_SYMBOL(__scsi_alloc_queue); + +struct request_queue *scsi_alloc_queue(struct scsi_device *sdev) +{ + struct request_queue *q; + + q = __scsi_alloc_queue(sdev->host, scsi_request_fn); + if (!q) + return NULL; + + blk_queue_prep_rq(q, scsi_prep_fn); + blk_queue_unprep_rq(q, scsi_unprep_fn); + blk_queue_softirq_done(q, scsi_softirq_done); + blk_queue_rq_timed_out(q, scsi_times_out); + blk_queue_lld_busy(q, scsi_lld_busy); + return q; +} + +static struct blk_mq_ops scsi_mq_ops = { + .map_queue = blk_mq_map_queue, + .queue_rq = scsi_queue_rq, + .complete = scsi_softirq_done, + .timeout = scsi_timeout, + .init_request = scsi_init_request, + .exit_request = scsi_exit_request, +}; + +struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev) +{ + sdev->request_queue = blk_mq_init_queue(&sdev->host->tag_set); + if (IS_ERR(sdev->request_queue)) + return NULL; + + sdev->request_queue->queuedata = sdev; + __scsi_init_queue(sdev->host, sdev->request_queue); + return sdev->request_queue; +} + +int scsi_mq_setup_tags(struct Scsi_Host *shost) +{ + unsigned int cmd_size, sgl_size, tbl_size; + + tbl_size = shost->sg_tablesize; + if (tbl_size > SCSI_MAX_SG_SEGMENTS) + tbl_size = SCSI_MAX_SG_SEGMENTS; + sgl_size = tbl_size * sizeof(struct scatterlist); + cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size; + if (scsi_host_get_prot(shost)) + cmd_size += sizeof(struct scsi_data_buffer) + sgl_size; + + memset(&shost->tag_set, 0, sizeof(shost->tag_set)); + shost->tag_set.ops = &scsi_mq_ops; + shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1; + shost->tag_set.queue_depth = shost->can_queue; + shost->tag_set.cmd_size = cmd_size; + shost->tag_set.numa_node = NUMA_NO_NODE; + shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; + shost->tag_set.flags |= + BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy); + shost->tag_set.driver_data = shost; + + return blk_mq_alloc_tag_set(&shost->tag_set); +} + +void scsi_mq_destroy_tags(struct Scsi_Host *shost) +{ + blk_mq_free_tag_set(&shost->tag_set); +} + +/* + * 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; +} +EXPORT_SYMBOL(scsi_block_requests); + +/* + * 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); +} +EXPORT_SYMBOL(scsi_unblock_requests); + +int __init scsi_init_queue(void) +{ + int i; + + scsi_sdb_cache = kmem_cache_create("scsi_data_buffer", + sizeof(struct scsi_data_buffer), + 0, 0, NULL); + if (!scsi_sdb_cache) { + printk(KERN_ERR "SCSI: can't init scsi sdb cache\n"); + return -ENOMEM; + } + + 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); + if (!sgp->slab) { + printk(KERN_ERR "SCSI: can't init sg slab %s\n", + sgp->name); + goto cleanup_sdb; + } + + sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE, + sgp->slab); + if (!sgp->pool) { + printk(KERN_ERR "SCSI: can't init sg mempool %s\n", + sgp->name); + goto cleanup_sdb; + } + } + + return 0; + +cleanup_sdb: + for (i = 0; i < SG_MEMPOOL_NR; i++) { + struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; + if (sgp->pool) + mempool_destroy(sgp->pool); + if (sgp->slab) + kmem_cache_destroy(sgp->slab); + } + kmem_cache_destroy(scsi_sdb_cache); + + return -ENOMEM; +} + +void scsi_exit_queue(void) +{ + int i; + + kmem_cache_destroy(scsi_sdb_cache); + + 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_select - issue a mode select + * @sdev: SCSI device to be queried + * @pf: Page format bit (1 == standard, 0 == vendor specific) + * @sp: Save page bit (0 == don't save, 1 == save) + * @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 + * @sshdr: place to put sense data (or NULL if no sense to be collected). + * must be SCSI_SENSE_BUFFERSIZE big. + * + * Returns zero if successful; negative error number or scsi + * status on error + * + */ +int +scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage, + unsigned char *buffer, int len, int timeout, int retries, + struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) +{ + unsigned char cmd[10]; + unsigned char *real_buffer; + int ret; + + memset(cmd, 0, sizeof(cmd)); + cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0); + + if (sdev->use_10_for_ms) { + if (len > 65535) + return -EINVAL; + real_buffer = kmalloc(8 + len, GFP_KERNEL); + if (!real_buffer) + return -ENOMEM; + memcpy(real_buffer + 8, buffer, len); + len += 8; + real_buffer[0] = 0; + real_buffer[1] = 0; + real_buffer[2] = data->medium_type; + real_buffer[3] = data->device_specific; + real_buffer[4] = data->longlba ? 0x01 : 0; + real_buffer[5] = 0; + real_buffer[6] = data->block_descriptor_length >> 8; + real_buffer[7] = data->block_descriptor_length; + + cmd[0] = MODE_SELECT_10; + cmd[7] = len >> 8; + cmd[8] = len; + } else { + if (len > 255 || data->block_descriptor_length > 255 || + data->longlba) + return -EINVAL; + + real_buffer = kmalloc(4 + len, GFP_KERNEL); + if (!real_buffer) + return -ENOMEM; + memcpy(real_buffer + 4, buffer, len); + len += 4; + real_buffer[0] = 0; + real_buffer[1] = data->medium_type; + real_buffer[2] = data->device_specific; + real_buffer[3] = data->block_descriptor_length; + + + cmd[0] = MODE_SELECT; + cmd[4] = len; + } + + ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len, + sshdr, timeout, retries, NULL); + kfree(real_buffer); + return ret; +} +EXPORT_SYMBOL_GPL(scsi_mode_select); + +/** + * scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary. + * @sdev: SCSI device to be queried + * @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 + * @sshdr: place to put sense data (or NULL if no sense to be collected). + * must be SCSI_SENSE_BUFFERSIZE big. + * + * 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_sense_hdr *sshdr) +{ + unsigned char cmd[12]; + int use_10_for_ms; + int header_length; + int result; + struct scsi_sense_hdr my_sshdr; + + memset(data, 0, sizeof(*data)); + memset(&cmd[0], 0, 12); + cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */ + cmd[2] = modepage; + + /* caller might not be interested in sense, but we need it */ + if (!sshdr) + sshdr = &my_sshdr; + + retry: + use_10_for_ms = sdev->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; + } + + memset(buffer, 0, len); + + result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len, + sshdr, timeout, retries, NULL); + + /* 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(result) && + (driver_byte(result) & DRIVER_SENSE)) { + if (scsi_sense_valid(sshdr)) { + if ((sshdr->sense_key == ILLEGAL_REQUEST) && + (sshdr->asc == 0x20) && (sshdr->ascq == 0)) { + /* + * Invalid command operation code + */ + sdev->use_10_for_ms = 0; + goto retry; + } + } + } + + if(scsi_status_is_good(result)) { + if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b && + (modepage == 6 || modepage == 8))) { + /* Initio breakage? */ + header_length = 0; + data->length = 13; + data->medium_type = 0; + data->device_specific = 0; + data->longlba = 0; + data->block_descriptor_length = 0; + } else 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]; + } + data->header_length = header_length; + } + + return result; +} +EXPORT_SYMBOL(scsi_mode_sense); + +/** + * scsi_test_unit_ready - test if unit is ready + * @sdev: scsi device to change the state of. + * @timeout: command timeout + * @retries: number of retries before failing + * @sshdr_external: Optional pointer to struct scsi_sense_hdr for + * returning sense. Make sure that this is cleared before passing + * in. + * + * Returns zero if unsuccessful or an error if TUR failed. For + * removable media, UNIT_ATTENTION sets ->changed flag. + **/ +int +scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries, + struct scsi_sense_hdr *sshdr_external) +{ + char cmd[] = { + TEST_UNIT_READY, 0, 0, 0, 0, 0, + }; + struct scsi_sense_hdr *sshdr; + int result; + + if (!sshdr_external) + sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL); + else + sshdr = sshdr_external; + + /* try to eat the UNIT_ATTENTION if there are enough retries */ + do { + result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr, + timeout, retries, NULL); + if (sdev->removable && scsi_sense_valid(sshdr) && + sshdr->sense_key == UNIT_ATTENTION) + sdev->changed = 1; + } while (scsi_sense_valid(sshdr) && + sshdr->sense_key == UNIT_ATTENTION && --retries); + + if (!sshdr_external) + kfree(sshdr); + return result; +} +EXPORT_SYMBOL(scsi_test_unit_ready); + +/** + * 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: + switch (oldstate) { + case SDEV_CREATED_BLOCK: + break; + default: + goto illegal; + } + break; + + case SDEV_RUNNING: + switch (oldstate) { + case SDEV_CREATED: + case SDEV_OFFLINE: + case SDEV_TRANSPORT_OFFLINE: + case SDEV_QUIESCE: + case SDEV_BLOCK: + break; + default: + goto illegal; + } + break; + + case SDEV_QUIESCE: + switch (oldstate) { + case SDEV_RUNNING: + case SDEV_OFFLINE: + case SDEV_TRANSPORT_OFFLINE: + break; + default: + goto illegal; + } + break; + + case SDEV_OFFLINE: + case SDEV_TRANSPORT_OFFLINE: + switch (oldstate) { + case SDEV_CREATED: + case SDEV_RUNNING: + case SDEV_QUIESCE: + case SDEV_BLOCK: + break; + default: + goto illegal; + } + break; + + case SDEV_BLOCK: + switch (oldstate) { + case SDEV_RUNNING: + case SDEV_CREATED_BLOCK: + break; + default: + goto illegal; + } + break; + + case SDEV_CREATED_BLOCK: + switch (oldstate) { + case SDEV_CREATED: + break; + default: + goto illegal; + } + break; + + case SDEV_CANCEL: + switch (oldstate) { + case SDEV_CREATED: + case SDEV_RUNNING: + case SDEV_QUIESCE: + case SDEV_OFFLINE: + case SDEV_TRANSPORT_OFFLINE: + case SDEV_BLOCK: + break; + default: + goto illegal; + } + break; + + case SDEV_DEL: + switch (oldstate) { + case SDEV_CREATED: + case SDEV_RUNNING: + case SDEV_OFFLINE: + case SDEV_TRANSPORT_OFFLINE: + case SDEV_CANCEL: + case SDEV_CREATED_BLOCK: + break; + default: + goto illegal; + } + break; + + } + sdev->sdev_state = state; + return 0; + + illegal: + SCSI_LOG_ERROR_RECOVERY(1, + sdev_printk(KERN_ERR, sdev, + "Illegal state transition %s->%s", + scsi_device_state_name(oldstate), + scsi_device_state_name(state)) + ); + return -EINVAL; +} +EXPORT_SYMBOL(scsi_device_set_state); + +/** + * sdev_evt_emit - emit a single SCSI device uevent + * @sdev: associated SCSI device + * @evt: event to emit + * + * Send a single uevent (scsi_event) to the associated scsi_device. + */ +static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt) +{ + int idx = 0; + char *envp[3]; + + switch (evt->evt_type) { + case SDEV_EVT_MEDIA_CHANGE: + envp[idx++] = "SDEV_MEDIA_CHANGE=1"; + break; + case SDEV_EVT_INQUIRY_CHANGE_REPORTED: + envp[idx++] = "SDEV_UA=INQUIRY_DATA_HAS_CHANGED"; + break; + case SDEV_EVT_CAPACITY_CHANGE_REPORTED: + envp[idx++] = "SDEV_UA=CAPACITY_DATA_HAS_CHANGED"; + break; + case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED: + envp[idx++] = "SDEV_UA=THIN_PROVISIONING_SOFT_THRESHOLD_REACHED"; + break; + case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED: + envp[idx++] = "SDEV_UA=MODE_PARAMETERS_CHANGED"; + break; + case SDEV_EVT_LUN_CHANGE_REPORTED: + envp[idx++] = "SDEV_UA=REPORTED_LUNS_DATA_HAS_CHANGED"; + break; + default: + /* do nothing */ + break; + } + + envp[idx++] = NULL; + + kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp); +} + +/** + * sdev_evt_thread - send a uevent for each scsi event + * @work: work struct for scsi_device + * + * Dispatch queued events to their associated scsi_device kobjects + * as uevents. + */ +void scsi_evt_thread(struct work_struct *work) +{ + struct scsi_device *sdev; + enum scsi_device_event evt_type; + LIST_HEAD(event_list); + + sdev = container_of(work, struct scsi_device, event_work); + + for (evt_type = SDEV_EVT_FIRST; evt_type <= SDEV_EVT_LAST; evt_type++) + if (test_and_clear_bit(evt_type, sdev->pending_events)) + sdev_evt_send_simple(sdev, evt_type, GFP_KERNEL); + + while (1) { + struct scsi_event *evt; + struct list_head *this, *tmp; + unsigned long flags; + + spin_lock_irqsave(&sdev->list_lock, flags); + list_splice_init(&sdev->event_list, &event_list); + spin_unlock_irqrestore(&sdev->list_lock, flags); + + if (list_empty(&event_list)) + break; + + list_for_each_safe(this, tmp, &event_list) { + evt = list_entry(this, struct scsi_event, node); + list_del(&evt->node); + scsi_evt_emit(sdev, evt); + kfree(evt); + } + } +} + +/** + * sdev_evt_send - send asserted event to uevent thread + * @sdev: scsi_device event occurred on + * @evt: event to send + * + * Assert scsi device event asynchronously. + */ +void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt) +{ + unsigned long flags; + +#if 0 + /* FIXME: currently this check eliminates all media change events + * for polled devices. Need to update to discriminate between AN + * and polled events */ + if (!test_bit(evt->evt_type, sdev->supported_events)) { + kfree(evt); + return; + } +#endif + + spin_lock_irqsave(&sdev->list_lock, flags); + list_add_tail(&evt->node, &sdev->event_list); + schedule_work(&sdev->event_work); + spin_unlock_irqrestore(&sdev->list_lock, flags); +} +EXPORT_SYMBOL_GPL(sdev_evt_send); + +/** + * sdev_evt_alloc - allocate a new scsi event + * @evt_type: type of event to allocate + * @gfpflags: GFP flags for allocation + * + * Allocates and returns a new scsi_event. + */ +struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type, + gfp_t gfpflags) +{ + struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags); + if (!evt) + return NULL; + + evt->evt_type = evt_type; + INIT_LIST_HEAD(&evt->node); + + /* evt_type-specific initialization, if any */ + switch (evt_type) { + case SDEV_EVT_MEDIA_CHANGE: + case SDEV_EVT_INQUIRY_CHANGE_REPORTED: + case SDEV_EVT_CAPACITY_CHANGE_REPORTED: + case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED: + case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED: + case SDEV_EVT_LUN_CHANGE_REPORTED: + default: + /* do nothing */ + break; + } + + return evt; +} +EXPORT_SYMBOL_GPL(sdev_evt_alloc); + +/** + * sdev_evt_send_simple - send asserted event to uevent thread + * @sdev: scsi_device event occurred on + * @evt_type: type of event to send + * @gfpflags: GFP flags for allocation + * + * Assert scsi device event asynchronously, given an event type. + */ +void sdev_evt_send_simple(struct scsi_device *sdev, + enum scsi_device_event evt_type, gfp_t gfpflags) +{ + struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags); + if (!evt) { + sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n", + evt_type); + return; + } + + sdev_evt_send(sdev, evt); +} +EXPORT_SYMBOL_GPL(sdev_evt_send_simple); + +/** + * 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 (atomic_read(&sdev->device_busy)) { + msleep_interruptible(200); + 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) +{ + /* check if the device state was mutated prior to resume, and if + * so assume the state is being managed elsewhere (for example + * device deleted during suspend) + */ + if (sdev->sdev_state != SDEV_QUIESCE || + scsi_device_set_state(sdev, SDEV_RUNNING)) + return; + scsi_run_queue(sdev->request_queue); +} +EXPORT_SYMBOL(scsi_device_resume); + +static void +device_quiesce_fn(struct scsi_device *sdev, void *data) +{ + scsi_device_quiesce(sdev); +} + +void +scsi_target_quiesce(struct scsi_target *starget) +{ + starget_for_each_device(starget, NULL, device_quiesce_fn); +} +EXPORT_SYMBOL(scsi_target_quiesce); + +static void +device_resume_fn(struct scsi_device *sdev, void *data) +{ + scsi_device_resume(sdev); +} + +void +scsi_target_resume(struct scsi_target *starget) +{ + starget_for_each_device(starget, NULL, device_resume_fn); +} +EXPORT_SYMBOL(scsi_target_resume); + +/** + * scsi_internal_device_block - internal function to put a device temporarily into the SDEV_BLOCK state + * @sdev: device to block + * + * Block request made by scsi lld's to temporarily stop all + * scsi commands on the specified device. Called from interrupt + * or normal process context. + * + * Returns zero if successful or error if not + * + * Notes: + * This routine transitions the device to the SDEV_BLOCK state + * (which must be a legal transition). When the device is in this + * state, all commands are deferred until the scsi lld reenables + * the device with scsi_device_unblock or device_block_tmo fires. + */ +int +scsi_internal_device_block(struct scsi_device *sdev) +{ + struct request_queue *q = sdev->request_queue; + unsigned long flags; + int err = 0; + + err = scsi_device_set_state(sdev, SDEV_BLOCK); + if (err) { + err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK); + + if (err) + return err; + } + + /* + * The device has transitioned to SDEV_BLOCK. Stop the + * block layer from calling the midlayer with this device's + * request queue. + */ + if (q->mq_ops) { + blk_mq_stop_hw_queues(q); + } else { + spin_lock_irqsave(q->queue_lock, flags); + blk_stop_queue(q); + spin_unlock_irqrestore(q->queue_lock, flags); + } + + return 0; +} +EXPORT_SYMBOL_GPL(scsi_internal_device_block); + +/** + * scsi_internal_device_unblock - resume a device after a block request + * @sdev: device to resume + * @new_state: state to set devices to after unblocking + * + * Called by scsi lld's or the midlayer to restart the device queue + * for the previously suspended scsi device. Called from interrupt or + * normal process context. + * + * Returns zero if successful or error if not. + * + * Notes: + * This routine transitions the device to the SDEV_RUNNING state + * or to one of the offline states (which must be a legal transition) + * allowing the midlayer to goose the queue for this device. + */ +int +scsi_internal_device_unblock(struct scsi_device *sdev, + enum scsi_device_state new_state) +{ + struct request_queue *q = sdev->request_queue; + unsigned long flags; + + /* + * Try to transition the scsi device to SDEV_RUNNING or one of the + * offlined states and goose the device queue if successful. + */ + if ((sdev->sdev_state == SDEV_BLOCK) || + (sdev->sdev_state == SDEV_TRANSPORT_OFFLINE)) + sdev->sdev_state = new_state; + else if (sdev->sdev_state == SDEV_CREATED_BLOCK) { + if (new_state == SDEV_TRANSPORT_OFFLINE || + new_state == SDEV_OFFLINE) + sdev->sdev_state = new_state; + else + sdev->sdev_state = SDEV_CREATED; + } else if (sdev->sdev_state != SDEV_CANCEL && + sdev->sdev_state != SDEV_OFFLINE) + return -EINVAL; + + if (q->mq_ops) { + blk_mq_start_stopped_hw_queues(q, false); + } else { + spin_lock_irqsave(q->queue_lock, flags); + blk_start_queue(q); + spin_unlock_irqrestore(q->queue_lock, flags); + } + + return 0; +} +EXPORT_SYMBOL_GPL(scsi_internal_device_unblock); + +static void +device_block(struct scsi_device *sdev, void *data) +{ + scsi_internal_device_block(sdev); +} + +static int +target_block(struct device *dev, void *data) +{ + if (scsi_is_target_device(dev)) + starget_for_each_device(to_scsi_target(dev), NULL, + device_block); + return 0; +} + +void +scsi_target_block(struct device *dev) +{ + if (scsi_is_target_device(dev)) + starget_for_each_device(to_scsi_target(dev), NULL, + device_block); + else + device_for_each_child(dev, NULL, target_block); +} +EXPORT_SYMBOL_GPL(scsi_target_block); + +static void +device_unblock(struct scsi_device *sdev, void *data) +{ + scsi_internal_device_unblock(sdev, *(enum scsi_device_state *)data); +} + +static int +target_unblock(struct device *dev, void *data) +{ + if (scsi_is_target_device(dev)) + starget_for_each_device(to_scsi_target(dev), data, + device_unblock); + return 0; +} + +void +scsi_target_unblock(struct device *dev, enum scsi_device_state new_state) +{ + if (scsi_is_target_device(dev)) + starget_for_each_device(to_scsi_target(dev), &new_state, + device_unblock); + else + device_for_each_child(dev, &new_state, target_unblock); +} +EXPORT_SYMBOL_GPL(scsi_target_unblock); + +/** + * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt + * @sgl: scatter-gather list + * @sg_count: number of segments in sg + * @offset: offset in bytes into sg, on return offset into the mapped area + * @len: bytes to map, on return number of bytes mapped + * + * Returns virtual address of the start of the mapped page + */ +void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count, + size_t *offset, size_t *len) +{ + int i; + size_t sg_len = 0, len_complete = 0; + struct scatterlist *sg; + struct page *page; + + WARN_ON(!irqs_disabled()); + + for_each_sg(sgl, sg, sg_count, i) { + len_complete = sg_len; /* Complete sg-entries */ + sg_len += sg->length; + if (sg_len > *offset) + break; + } + + if (unlikely(i == sg_count)) { + printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, " + "elements %d\n", + __func__, sg_len, *offset, sg_count); + WARN_ON(1); + return NULL; + } + + /* Offset starting from the beginning of first page in this sg-entry */ + *offset = *offset - len_complete + sg->offset; + + /* Assumption: contiguous pages can be accessed as "page + i" */ + page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT)); + *offset &= ~PAGE_MASK; + + /* Bytes in this sg-entry from *offset to the end of the page */ + sg_len = PAGE_SIZE - *offset; + if (*len > sg_len) + *len = sg_len; + + return kmap_atomic(page); +} +EXPORT_SYMBOL(scsi_kmap_atomic_sg); + +/** + * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg + * @virt: virtual address to be unmapped + */ +void scsi_kunmap_atomic_sg(void *virt) +{ + kunmap_atomic(virt); +} +EXPORT_SYMBOL(scsi_kunmap_atomic_sg); + +void sdev_disable_disk_events(struct scsi_device *sdev) +{ + atomic_inc(&sdev->disk_events_disable_depth); +} +EXPORT_SYMBOL(sdev_disable_disk_events); + +void sdev_enable_disk_events(struct scsi_device *sdev) +{ + if (WARN_ON_ONCE(atomic_read(&sdev->disk_events_disable_depth) <= 0)) + return; + atomic_dec(&sdev->disk_events_disable_depth); +} +EXPORT_SYMBOL(sdev_enable_disk_events); |