--- /dev/null
+/*
+ * 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);
Code Review / kvmfornfv.git / blobdiff