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-rw-r--r--drivers/scsi/scsi_lib.c3337
1 files changed, 3337 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
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index 0000000000..c2f647a7c1
--- /dev/null
+++ b/drivers/scsi/scsi_lib.c
@@ -0,0 +1,3337 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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/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/blk-integrity.h>
+#include <linux/ratelimit.h>
+#include <asm/unaligned.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 <scsi/scsi_transport.h> /* __scsi_init_queue() */
+#include <scsi/scsi_dh.h>
+
+#include <trace/events/scsi.h>
+
+#include "scsi_debugfs.h"
+#include "scsi_priv.h"
+#include "scsi_logging.h"
+
+/*
+ * Size of integrity metadata is usually small, 1 inline sg should
+ * cover normal cases.
+ */
+#ifdef CONFIG_ARCH_NO_SG_CHAIN
+#define SCSI_INLINE_PROT_SG_CNT 0
+#define SCSI_INLINE_SG_CNT 0
+#else
+#define SCSI_INLINE_PROT_SG_CNT 1
+#define SCSI_INLINE_SG_CNT 2
+#endif
+
+static struct kmem_cache *scsi_sense_cache;
+static DEFINE_MUTEX(scsi_sense_cache_mutex);
+
+static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd);
+
+int scsi_init_sense_cache(struct Scsi_Host *shost)
+{
+ int ret = 0;
+
+ mutex_lock(&scsi_sense_cache_mutex);
+ if (!scsi_sense_cache) {
+ scsi_sense_cache =
+ kmem_cache_create_usercopy("scsi_sense_cache",
+ SCSI_SENSE_BUFFERSIZE, 0, SLAB_HWCACHE_ALIGN,
+ 0, SCSI_SENSE_BUFFERSIZE, NULL);
+ if (!scsi_sense_cache)
+ ret = -ENOMEM;
+ }
+ mutex_unlock(&scsi_sense_cache_mutex);
+ return ret;
+}
+
+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, unsigned long msecs)
+{
+ struct request *rq = scsi_cmd_to_rq(cmd);
+
+ if (rq->rq_flags & RQF_DONTPREP) {
+ rq->rq_flags &= ~RQF_DONTPREP;
+ scsi_mq_uninit_cmd(cmd);
+ } else {
+ WARN_ON_ONCE(true);
+ }
+
+ blk_mq_requeue_request(rq, false);
+ if (!scsi_host_in_recovery(cmd->device->host))
+ blk_mq_delay_kick_requeue_list(rq->q, msecs);
+}
+
+/**
+ * __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, bool unbusy)
+{
+ struct scsi_device *device = cmd->device;
+
+ 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, cmd);
+
+ /*
+ * 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_mq_destroy_queue() finishes.
+ */
+ cmd->result = 0;
+
+ blk_mq_requeue_request(scsi_cmd_to_rq(cmd),
+ !scsi_host_in_recovery(cmd->device->host));
+}
+
+/**
+ * scsi_queue_insert - Reinsert a command in the queue.
+ * @cmd: command that we are adding to queue.
+ * @reason: why we are inserting command to queue.
+ *
+ * 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.
+ *
+ * Context: 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, true);
+}
+
+/**
+ * scsi_execute_cmd - insert request and wait for the result
+ * @sdev: scsi_device
+ * @cmd: scsi command
+ * @opf: block layer request cmd_flags
+ * @buffer: data buffer
+ * @bufflen: len of buffer
+ * @timeout: request timeout in HZ
+ * @retries: number of times to retry request
+ * @args: Optional args. See struct definition for field descriptions
+ *
+ * Returns the scsi_cmnd result field if a command was executed, or a negative
+ * Linux error code if we didn't get that far.
+ */
+int scsi_execute_cmd(struct scsi_device *sdev, const unsigned char *cmd,
+ blk_opf_t opf, void *buffer, unsigned int bufflen,
+ int timeout, int retries,
+ const struct scsi_exec_args *args)
+{
+ static const struct scsi_exec_args default_args;
+ struct request *req;
+ struct scsi_cmnd *scmd;
+ int ret;
+
+ if (!args)
+ args = &default_args;
+ else if (WARN_ON_ONCE(args->sense &&
+ args->sense_len != SCSI_SENSE_BUFFERSIZE))
+ return -EINVAL;
+
+ req = scsi_alloc_request(sdev->request_queue, opf, args->req_flags);
+ if (IS_ERR(req))
+ return PTR_ERR(req);
+
+ if (bufflen) {
+ ret = blk_rq_map_kern(sdev->request_queue, req,
+ buffer, bufflen, GFP_NOIO);
+ if (ret)
+ goto out;
+ }
+ scmd = blk_mq_rq_to_pdu(req);
+ scmd->cmd_len = COMMAND_SIZE(cmd[0]);
+ memcpy(scmd->cmnd, cmd, scmd->cmd_len);
+ scmd->allowed = retries;
+ scmd->flags |= args->scmd_flags;
+ req->timeout = timeout;
+ req->rq_flags |= RQF_QUIET;
+
+ /*
+ * head injection *required* here otherwise quiesce won't work
+ */
+ blk_execute_rq(req, true);
+
+ /*
+ * 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(scmd->resid_len > 0 && scmd->resid_len <= bufflen))
+ memset(buffer + bufflen - scmd->resid_len, 0, scmd->resid_len);
+
+ if (args->resid)
+ *args->resid = scmd->resid_len;
+ if (args->sense)
+ memcpy(args->sense, scmd->sense_buffer, SCSI_SENSE_BUFFERSIZE);
+ if (args->sshdr)
+ scsi_normalize_sense(scmd->sense_buffer, scmd->sense_len,
+ args->sshdr);
+
+ ret = scmd->result;
+ out:
+ blk_mq_free_request(req);
+
+ return ret;
+}
+EXPORT_SYMBOL(scsi_execute_cmd);
+
+/*
+ * Wake up the error handler if necessary. Avoid as follows that the error
+ * handler is not woken up if host in-flight requests number ==
+ * shost->host_failed: use call_rcu() in scsi_eh_scmd_add() in combination
+ * with an RCU read lock in this function to ensure that this function in
+ * its entirety either finishes before scsi_eh_scmd_add() increases the
+ * host_failed counter or that it notices the shost state change made by
+ * scsi_eh_scmd_add().
+ */
+static void scsi_dec_host_busy(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
+{
+ unsigned long flags;
+
+ rcu_read_lock();
+ __clear_bit(SCMD_STATE_INFLIGHT, &cmd->state);
+ if (unlikely(scsi_host_in_recovery(shost))) {
+ spin_lock_irqsave(shost->host_lock, flags);
+ if (shost->host_failed || shost->host_eh_scheduled)
+ scsi_eh_wakeup(shost);
+ spin_unlock_irqrestore(shost->host_lock, flags);
+ }
+ rcu_read_unlock();
+}
+
+void scsi_device_unbusy(struct scsi_device *sdev, struct scsi_cmnd *cmd)
+{
+ struct Scsi_Host *shost = sdev->host;
+ struct scsi_target *starget = scsi_target(sdev);
+
+ scsi_dec_host_busy(shost, cmd);
+
+ if (starget->can_queue > 0)
+ atomic_dec(&starget->target_busy);
+
+ sbitmap_put(&sdev->budget_map, cmd->budget_token);
+ cmd->budget_token = -1;
+}
+
+/*
+ * Kick the queue of SCSI device @sdev if @sdev != current_sdev. Called with
+ * interrupts disabled.
+ */
+static void scsi_kick_sdev_queue(struct scsi_device *sdev, void *data)
+{
+ struct scsi_device *current_sdev = data;
+
+ if (sdev != current_sdev)
+ blk_mq_run_hw_queues(sdev->request_queue, true);
+}
+
+/*
+ * 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_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.
+ */
+ blk_mq_run_hw_queues(current_sdev->request_queue,
+ shost->queuecommand_may_block);
+
+ spin_lock_irqsave(shost->host_lock, flags);
+ if (!starget->starget_sdev_user)
+ __starget_for_each_device(starget, current_sdev,
+ scsi_kick_sdev_queue);
+ spin_unlock_irqrestore(shost->host_lock, flags);
+}
+
+static inline bool scsi_device_is_busy(struct scsi_device *sdev)
+{
+ if (scsi_device_busy(sdev) >= 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 (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_mq_destroy_queue() before the queue is run from this
+ * function then blk_run_queue() will return immediately since
+ * blk_mq_destroy_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);
+
+ blk_mq_run_hw_queues(slq, false);
+ 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);
+}
+
+/**
+ * scsi_run_queue - Select a proper request queue to serve next.
+ * @q: last request's queue
+ *
+ * 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);
+
+ /* Note: blk_mq_kick_requeue_list() runs the queue asynchronously. */
+ blk_mq_kick_requeue_list(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);
+}
+
+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 void scsi_uninit_cmd(struct scsi_cmnd *cmd)
+{
+ if (!blk_rq_is_passthrough(scsi_cmd_to_rq(cmd))) {
+ struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
+
+ if (drv->uninit_command)
+ drv->uninit_command(cmd);
+ }
+}
+
+void scsi_free_sgtables(struct scsi_cmnd *cmd)
+{
+ if (cmd->sdb.table.nents)
+ sg_free_table_chained(&cmd->sdb.table,
+ SCSI_INLINE_SG_CNT);
+ if (scsi_prot_sg_count(cmd))
+ sg_free_table_chained(&cmd->prot_sdb->table,
+ SCSI_INLINE_PROT_SG_CNT);
+}
+EXPORT_SYMBOL_GPL(scsi_free_sgtables);
+
+static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
+{
+ scsi_free_sgtables(cmd);
+ scsi_uninit_cmd(cmd);
+}
+
+static void scsi_run_queue_async(struct scsi_device *sdev)
+{
+ if (scsi_host_in_recovery(sdev->host))
+ return;
+
+ if (scsi_target(sdev)->single_lun ||
+ !list_empty(&sdev->host->starved_list)) {
+ kblockd_schedule_work(&sdev->requeue_work);
+ } else {
+ /*
+ * smp_mb() present in sbitmap_queue_clear() or implied in
+ * .end_io is for ordering writing .device_busy in
+ * scsi_device_unbusy() and reading sdev->restarts.
+ */
+ int old = atomic_read(&sdev->restarts);
+
+ /*
+ * ->restarts has to be kept as non-zero if new budget
+ * contention occurs.
+ *
+ * No need to run queue when either another re-run
+ * queue wins in updating ->restarts or a new budget
+ * contention occurs.
+ */
+ if (old && atomic_cmpxchg(&sdev->restarts, old, 0) == old)
+ blk_mq_run_hw_queues(sdev->request_queue, true);
+ }
+}
+
+/* Returns false when no more bytes to process, true if there are more */
+static bool scsi_end_request(struct request *req, blk_status_t error,
+ unsigned int bytes)
+{
+ struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
+ struct scsi_device *sdev = cmd->device;
+ struct request_queue *q = sdev->request_queue;
+
+ if (blk_update_request(req, error, bytes))
+ return true;
+
+ // XXX:
+ if (blk_queue_add_random(q))
+ add_disk_randomness(req->q->disk);
+
+ if (!blk_rq_is_passthrough(req)) {
+ WARN_ON_ONCE(!(cmd->flags & SCMD_INITIALIZED));
+ cmd->flags &= ~SCMD_INITIALIZED;
+ }
+
+ /*
+ * Calling rcu_barrier() is not necessary here because the
+ * SCSI error handler guarantees that the function called by
+ * call_rcu() has been called before scsi_end_request() is
+ * called.
+ */
+ destroy_rcu_head(&cmd->rcu);
+
+ /*
+ * 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);
+
+ /*
+ * queue is still alive, so grab the ref for preventing it
+ * from being cleaned up during running queue.
+ */
+ percpu_ref_get(&q->q_usage_counter);
+
+ __blk_mq_end_request(req, error);
+
+ scsi_run_queue_async(sdev);
+
+ percpu_ref_put(&q->q_usage_counter);
+ return false;
+}
+
+/**
+ * scsi_result_to_blk_status - translate a SCSI result code into blk_status_t
+ * @result: scsi error code
+ *
+ * Translate a SCSI result code into a blk_status_t value.
+ */
+static blk_status_t scsi_result_to_blk_status(int result)
+{
+ /*
+ * Check the scsi-ml byte first in case we converted a host or status
+ * byte.
+ */
+ switch (scsi_ml_byte(result)) {
+ case SCSIML_STAT_OK:
+ break;
+ case SCSIML_STAT_RESV_CONFLICT:
+ return BLK_STS_RESV_CONFLICT;
+ case SCSIML_STAT_NOSPC:
+ return BLK_STS_NOSPC;
+ case SCSIML_STAT_MED_ERROR:
+ return BLK_STS_MEDIUM;
+ case SCSIML_STAT_TGT_FAILURE:
+ return BLK_STS_TARGET;
+ case SCSIML_STAT_DL_TIMEOUT:
+ return BLK_STS_DURATION_LIMIT;
+ }
+
+ switch (host_byte(result)) {
+ case DID_OK:
+ if (scsi_status_is_good(result))
+ return BLK_STS_OK;
+ return BLK_STS_IOERR;
+ case DID_TRANSPORT_FAILFAST:
+ case DID_TRANSPORT_MARGINAL:
+ return BLK_STS_TRANSPORT;
+ default:
+ return BLK_STS_IOERR;
+ }
+}
+
+/**
+ * scsi_rq_err_bytes - determine number of bytes till the next failure boundary
+ * @rq: request to examine
+ *
+ * Description:
+ * A request could be merge of IOs which require different failure
+ * handling. This function determines the number of bytes which
+ * can be failed from the beginning of the request without
+ * crossing into area which need to be retried further.
+ *
+ * Return:
+ * The number of bytes to fail.
+ */
+static unsigned int scsi_rq_err_bytes(const struct request *rq)
+{
+ blk_opf_t ff = rq->cmd_flags & REQ_FAILFAST_MASK;
+ unsigned int bytes = 0;
+ struct bio *bio;
+
+ if (!(rq->rq_flags & RQF_MIXED_MERGE))
+ return blk_rq_bytes(rq);
+
+ /*
+ * Currently the only 'mixing' which can happen is between
+ * different fastfail types. We can safely fail portions
+ * which have all the failfast bits that the first one has -
+ * the ones which are at least as eager to fail as the first
+ * one.
+ */
+ for (bio = rq->bio; bio; bio = bio->bi_next) {
+ if ((bio->bi_opf & ff) != ff)
+ break;
+ bytes += bio->bi_iter.bi_size;
+ }
+
+ /* this could lead to infinite loop */
+ BUG_ON(blk_rq_bytes(rq) && !bytes);
+ return bytes;
+}
+
+static bool scsi_cmd_runtime_exceeced(struct scsi_cmnd *cmd)
+{
+ struct request *req = scsi_cmd_to_rq(cmd);
+ unsigned long wait_for;
+
+ if (cmd->allowed == SCSI_CMD_RETRIES_NO_LIMIT)
+ return false;
+
+ wait_for = (cmd->allowed + 1) * req->timeout;
+ if (time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
+ scmd_printk(KERN_ERR, cmd, "timing out command, waited %lus\n",
+ wait_for/HZ);
+ return true;
+ }
+ return false;
+}
+
+/*
+ * When ALUA transition state is returned, reprep the cmd to
+ * use the ALUA handler's transition timeout. Delay the reprep
+ * 1 sec to avoid aggressive retries of the target in that
+ * state.
+ */
+#define ALUA_TRANSITION_REPREP_DELAY 1000
+
+/* Helper for scsi_io_completion() when special action required. */
+static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result)
+{
+ struct request *req = scsi_cmd_to_rq(cmd);
+ int level = 0;
+ enum {ACTION_FAIL, ACTION_REPREP, ACTION_DELAYED_REPREP,
+ ACTION_RETRY, ACTION_DELAYED_RETRY} action;
+ struct scsi_sense_hdr sshdr;
+ bool sense_valid;
+ bool sense_current = true; /* false implies "deferred sense" */
+ blk_status_t blk_stat;
+
+ sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
+ if (sense_valid)
+ sense_current = !scsi_sense_is_deferred(&sshdr);
+
+ blk_stat = scsi_result_to_blk_status(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_current) {
+ 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;
+ blk_stat = BLK_STS_PROTECTION;
+ /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
+ } else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
+ action = ACTION_FAIL;
+ blk_stat = BLK_STS_TARGET;
+ } else
+ action = ACTION_FAIL;
+ break;
+ case ABORTED_COMMAND:
+ action = ACTION_FAIL;
+ if (sshdr.asc == 0x10) /* DIF */
+ blk_stat = BLK_STS_PROTECTION;
+ 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 0x11: /* notify (enable spinup) required */
+ case 0x14: /* space allocation in progress */
+ case 0x1a: /* start stop unit in progress */
+ case 0x1b: /* sanitize in progress */
+ case 0x1d: /* configuration in progress */
+ case 0x24: /* depopulation in progress */
+ action = ACTION_DELAYED_RETRY;
+ break;
+ case 0x0a: /* ALUA state transition */
+ action = ACTION_DELAYED_REPREP;
+ break;
+ default:
+ action = ACTION_FAIL;
+ break;
+ }
+ } else
+ action = ACTION_FAIL;
+ break;
+ case VOLUME_OVERFLOW:
+ /* See SSC3rXX or current. */
+ action = ACTION_FAIL;
+ break;
+ case DATA_PROTECT:
+ action = ACTION_FAIL;
+ if ((sshdr.asc == 0x0C && sshdr.ascq == 0x12) ||
+ (sshdr.asc == 0x55 &&
+ (sshdr.ascq == 0x0E || sshdr.ascq == 0x0F))) {
+ /* Insufficient zone resources */
+ blk_stat = BLK_STS_ZONE_OPEN_RESOURCE;
+ }
+ break;
+ case COMPLETED:
+ fallthrough;
+ default:
+ action = ACTION_FAIL;
+ break;
+ }
+ } else
+ action = ACTION_FAIL;
+
+ if (action != ACTION_FAIL && scsi_cmd_runtime_exceeced(cmd))
+ action = ACTION_FAIL;
+
+ switch (action) {
+ case ACTION_FAIL:
+ /* Give up and fail the remainder of the request */
+ if (!(req->rq_flags & RQF_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 (sense_valid)
+ scsi_print_sense(cmd);
+ scsi_print_command(cmd);
+ }
+ }
+ if (!scsi_end_request(req, blk_stat, scsi_rq_err_bytes(req)))
+ return;
+ fallthrough;
+ case ACTION_REPREP:
+ scsi_mq_requeue_cmd(cmd, 0);
+ break;
+ case ACTION_DELAYED_REPREP:
+ scsi_mq_requeue_cmd(cmd, ALUA_TRANSITION_REPREP_DELAY);
+ break;
+ case ACTION_RETRY:
+ /* Retry the same command immediately */
+ __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, false);
+ break;
+ case ACTION_DELAYED_RETRY:
+ /* Retry the same command after a delay */
+ __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, false);
+ break;
+ }
+}
+
+/*
+ * Helper for scsi_io_completion() when cmd->result is non-zero. Returns a
+ * new result that may suppress further error checking. Also modifies
+ * *blk_statp in some cases.
+ */
+static int scsi_io_completion_nz_result(struct scsi_cmnd *cmd, int result,
+ blk_status_t *blk_statp)
+{
+ bool sense_valid;
+ bool sense_current = true; /* false implies "deferred sense" */
+ struct request *req = scsi_cmd_to_rq(cmd);
+ struct scsi_sense_hdr sshdr;
+
+ sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
+ if (sense_valid)
+ sense_current = !scsi_sense_is_deferred(&sshdr);
+
+ if (blk_rq_is_passthrough(req)) {
+ if (sense_valid) {
+ /*
+ * SG_IO wants current and deferred errors
+ */
+ cmd->sense_len = min(8 + cmd->sense_buffer[7],
+ SCSI_SENSE_BUFFERSIZE);
+ }
+ if (sense_current)
+ *blk_statp = scsi_result_to_blk_status(result);
+ } else if (blk_rq_bytes(req) == 0 && sense_current) {
+ /*
+ * Flush commands do not transfers any data, and thus cannot use
+ * good_bytes != blk_rq_bytes(req) as the signal for an error.
+ * This sets *blk_statp explicitly for the problem case.
+ */
+ *blk_statp = scsi_result_to_blk_status(result);
+ }
+ /*
+ * Recovered errors need reporting, but they're always treated as
+ * success, so fiddle the result code here. For passthrough requests
+ * we already took a copy of the original into sreq->result which
+ * is what gets returned to the user
+ */
+ if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
+ bool do_print = true;
+ /*
+ * if ATA PASS-THROUGH INFORMATION AVAILABLE [0x0, 0x1d]
+ * 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))
+ do_print = false;
+ else if (req->rq_flags & RQF_QUIET)
+ do_print = false;
+ if (do_print)
+ scsi_print_sense(cmd);
+ result = 0;
+ /* for passthrough, *blk_statp may be set */
+ *blk_statp = BLK_STS_OK;
+ }
+ /*
+ * Another corner case: the SCSI status byte is non-zero but 'good'.
+ * Example: PRE-FETCH command returns SAM_STAT_CONDITION_MET when
+ * it is able to fit nominated LBs in its cache (and SAM_STAT_GOOD
+ * if it can't fit). Treat SAM_STAT_CONDITION_MET and the related
+ * intermediate statuses (both obsolete in SAM-4) as good.
+ */
+ if ((result & 0xff) && scsi_status_is_good(result)) {
+ result = 0;
+ *blk_statp = BLK_STS_OK;
+ }
+ return result;
+}
+
+/**
+ * scsi_io_completion - Completion processing for SCSI commands.
+ * @cmd: command that is finished.
+ * @good_bytes: number of processed bytes.
+ *
+ * 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_mq_requeue_cmd(). 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_io_completion_action(). 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 blk_stat other than
+ * BLK_STS_OK, 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 *req = scsi_cmd_to_rq(cmd);
+ blk_status_t blk_stat = BLK_STS_OK;
+
+ if (unlikely(result)) /* a nz result may or may not be an error */
+ result = scsi_io_completion_nz_result(cmd, result, &blk_stat);
+
+ /*
+ * 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));
+
+ /*
+ * Failed, zero length commands always need to drop down
+ * to retry code. Fast path should return in this block.
+ */
+ if (likely(blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK)) {
+ if (likely(!scsi_end_request(req, blk_stat, good_bytes)))
+ return; /* no bytes remaining */
+ }
+
+ /* Kill remainder if no retries. */
+ if (unlikely(blk_stat && scsi_noretry_cmd(cmd))) {
+ if (scsi_end_request(req, blk_stat, blk_rq_bytes(req)))
+ WARN_ONCE(true,
+ "Bytes remaining after failed, no-retry command");
+ return;
+ }
+
+ /*
+ * If there had been no error, but we have leftover bytes in the
+ * request just queue the command up again.
+ */
+ if (likely(result == 0))
+ scsi_mq_requeue_cmd(cmd, 0);
+ else
+ scsi_io_completion_action(cmd, result);
+}
+
+static inline bool scsi_cmd_needs_dma_drain(struct scsi_device *sdev,
+ struct request *rq)
+{
+ return sdev->dma_drain_len && blk_rq_is_passthrough(rq) &&
+ !op_is_write(req_op(rq)) &&
+ sdev->host->hostt->dma_need_drain(rq);
+}
+
+/**
+ * scsi_alloc_sgtables - Allocate and initialize data and integrity scatterlists
+ * @cmd: SCSI command data structure to initialize.
+ *
+ * Initializes @cmd->sdb and also @cmd->prot_sdb if data integrity is enabled
+ * for @cmd.
+ *
+ * Returns:
+ * * BLK_STS_OK - on success
+ * * BLK_STS_RESOURCE - if the failure is retryable
+ * * BLK_STS_IOERR - if the failure is fatal
+ */
+blk_status_t scsi_alloc_sgtables(struct scsi_cmnd *cmd)
+{
+ struct scsi_device *sdev = cmd->device;
+ struct request *rq = scsi_cmd_to_rq(cmd);
+ unsigned short nr_segs = blk_rq_nr_phys_segments(rq);
+ struct scatterlist *last_sg = NULL;
+ blk_status_t ret;
+ bool need_drain = scsi_cmd_needs_dma_drain(sdev, rq);
+ int count;
+
+ if (WARN_ON_ONCE(!nr_segs))
+ return BLK_STS_IOERR;
+
+ /*
+ * Make sure there is space for the drain. The driver must adjust
+ * max_hw_segments to be prepared for this.
+ */
+ if (need_drain)
+ nr_segs++;
+
+ /*
+ * If sg table allocation fails, requeue request later.
+ */
+ if (unlikely(sg_alloc_table_chained(&cmd->sdb.table, nr_segs,
+ cmd->sdb.table.sgl, SCSI_INLINE_SG_CNT)))
+ return BLK_STS_RESOURCE;
+
+ /*
+ * Next, walk the list, and fill in the addresses and sizes of
+ * each segment.
+ */
+ count = __blk_rq_map_sg(rq->q, rq, cmd->sdb.table.sgl, &last_sg);
+
+ if (blk_rq_bytes(rq) & rq->q->dma_pad_mask) {
+ unsigned int pad_len =
+ (rq->q->dma_pad_mask & ~blk_rq_bytes(rq)) + 1;
+
+ last_sg->length += pad_len;
+ cmd->extra_len += pad_len;
+ }
+
+ if (need_drain) {
+ sg_unmark_end(last_sg);
+ last_sg = sg_next(last_sg);
+ sg_set_buf(last_sg, sdev->dma_drain_buf, sdev->dma_drain_len);
+ sg_mark_end(last_sg);
+
+ cmd->extra_len += sdev->dma_drain_len;
+ count++;
+ }
+
+ BUG_ON(count > cmd->sdb.table.nents);
+ cmd->sdb.table.nents = count;
+ cmd->sdb.length = blk_rq_payload_bytes(rq);
+
+ if (blk_integrity_rq(rq)) {
+ struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
+ int ivecs;
+
+ if (WARN_ON_ONCE(!prot_sdb)) {
+ /*
+ * This can happen if someone (e.g. multipath)
+ * queues a command to a device on an adapter
+ * that does not support DIX.
+ */
+ ret = BLK_STS_IOERR;
+ goto out_free_sgtables;
+ }
+
+ ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
+
+ if (sg_alloc_table_chained(&prot_sdb->table, ivecs,
+ prot_sdb->table.sgl,
+ SCSI_INLINE_PROT_SG_CNT)) {
+ ret = BLK_STS_RESOURCE;
+ goto out_free_sgtables;
+ }
+
+ count = blk_rq_map_integrity_sg(rq->q, rq->bio,
+ prot_sdb->table.sgl);
+ BUG_ON(count > ivecs);
+ BUG_ON(count > queue_max_integrity_segments(rq->q));
+
+ cmd->prot_sdb = prot_sdb;
+ cmd->prot_sdb->table.nents = count;
+ }
+
+ return BLK_STS_OK;
+out_free_sgtables:
+ scsi_free_sgtables(cmd);
+ return ret;
+}
+EXPORT_SYMBOL(scsi_alloc_sgtables);
+
+/**
+ * scsi_initialize_rq - initialize struct scsi_cmnd partially
+ * @rq: Request associated with the SCSI command to be initialized.
+ *
+ * This function initializes the members of struct scsi_cmnd that must be
+ * initialized before request processing starts and that won't be
+ * reinitialized if a SCSI command is requeued.
+ */
+static void scsi_initialize_rq(struct request *rq)
+{
+ struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+
+ memset(cmd->cmnd, 0, sizeof(cmd->cmnd));
+ cmd->cmd_len = MAX_COMMAND_SIZE;
+ cmd->sense_len = 0;
+ init_rcu_head(&cmd->rcu);
+ cmd->jiffies_at_alloc = jiffies;
+ cmd->retries = 0;
+}
+
+struct request *scsi_alloc_request(struct request_queue *q, blk_opf_t opf,
+ blk_mq_req_flags_t flags)
+{
+ struct request *rq;
+
+ rq = blk_mq_alloc_request(q, opf, flags);
+ if (!IS_ERR(rq))
+ scsi_initialize_rq(rq);
+ return rq;
+}
+EXPORT_SYMBOL_GPL(scsi_alloc_request);
+
+/*
+ * Only called when the request isn't completed by SCSI, and not freed by
+ * SCSI
+ */
+static void scsi_cleanup_rq(struct request *rq)
+{
+ if (rq->rq_flags & RQF_DONTPREP) {
+ scsi_mq_uninit_cmd(blk_mq_rq_to_pdu(rq));
+ rq->rq_flags &= ~RQF_DONTPREP;
+ }
+}
+
+/* Called before a request is prepared. See also scsi_mq_prep_fn(). */
+void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
+{
+ struct request *rq = scsi_cmd_to_rq(cmd);
+
+ if (!blk_rq_is_passthrough(rq) && !(cmd->flags & SCMD_INITIALIZED)) {
+ cmd->flags |= SCMD_INITIALIZED;
+ scsi_initialize_rq(rq);
+ }
+
+ cmd->device = dev;
+ INIT_LIST_HEAD(&cmd->eh_entry);
+ INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
+}
+
+static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev,
+ struct request *req)
+{
+ struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
+
+ /*
+ * Passthrough 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) {
+ blk_status_t ret = scsi_alloc_sgtables(cmd);
+ if (unlikely(ret != BLK_STS_OK))
+ return ret;
+ } else {
+ BUG_ON(blk_rq_bytes(req));
+
+ memset(&cmd->sdb, 0, sizeof(cmd->sdb));
+ }
+
+ cmd->transfersize = blk_rq_bytes(req);
+ return BLK_STS_OK;
+}
+
+static blk_status_t
+scsi_device_state_check(struct scsi_device *sdev, struct request *req)
+{
+ switch (sdev->sdev_state) {
+ case SDEV_CREATED:
+ return BLK_STS_OK;
+ 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.
+ */
+ if (!sdev->offline_already) {
+ sdev->offline_already = true;
+ sdev_printk(KERN_ERR, sdev,
+ "rejecting I/O to offline device\n");
+ }
+ return BLK_STS_IOERR;
+ 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");
+ return BLK_STS_IOERR;
+ case SDEV_BLOCK:
+ case SDEV_CREATED_BLOCK:
+ return BLK_STS_RESOURCE;
+ case SDEV_QUIESCE:
+ /*
+ * If the device is blocked we only accept power management
+ * commands.
+ */
+ if (req && WARN_ON_ONCE(!(req->rq_flags & RQF_PM)))
+ return BLK_STS_RESOURCE;
+ return BLK_STS_OK;
+ default:
+ /*
+ * For any other not fully online state we only allow
+ * power management commands.
+ */
+ if (req && !(req->rq_flags & RQF_PM))
+ return BLK_STS_OFFLINE;
+ return BLK_STS_OK;
+ }
+}
+
+/*
+ * scsi_dev_queue_ready: if we can send requests to sdev, assign one token
+ * and return the token else return -1.
+ */
+static inline int scsi_dev_queue_ready(struct request_queue *q,
+ struct scsi_device *sdev)
+{
+ int token;
+
+ token = sbitmap_get(&sdev->budget_map);
+ if (atomic_read(&sdev->device_blocked)) {
+ if (token < 0)
+ goto out;
+
+ if (scsi_device_busy(sdev) > 1)
+ goto out_dec;
+
+ /*
+ * unblock after device_blocked iterates to zero
+ */
+ if (atomic_dec_return(&sdev->device_blocked) > 0)
+ goto out_dec;
+ SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
+ "unblocking device at zero depth\n"));
+ }
+
+ return token;
+out_dec:
+ if (token >= 0)
+ sbitmap_put(&sdev->budget_map, token);
+out:
+ return -1;
+}
+
+/*
+ * 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,
+ struct scsi_cmnd *cmd)
+{
+ if (atomic_read(&shost->host_blocked) > 0) {
+ if (scsi_host_busy(shost) > 0)
+ 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->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);
+ }
+
+ __set_bit(SCMD_STATE_INFLIGHT, &cmd->state);
+
+ 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:
+ scsi_dec_host_busy(shost, cmd);
+ 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 bool scsi_mq_lld_busy(struct request_queue *q)
+{
+ struct scsi_device *sdev = q->queuedata;
+ struct Scsi_Host *shost;
+
+ if (blk_queue_dying(q))
+ return false;
+
+ 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 true;
+
+ return false;
+}
+
+/*
+ * Block layer request completion callback. May be called from interrupt
+ * context.
+ */
+static void scsi_complete(struct request *rq)
+{
+ struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+ enum scsi_disposition 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 && scsi_cmd_runtime_exceeced(cmd))
+ 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:
+ scsi_eh_scmd_add(cmd);
+ break;
+ }
+}
+
+/**
+ * scsi_dispatch_cmd - 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"));
+ atomic_dec(&cmd->device->iorequest_cnt);
+ 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) {
+ atomic_dec(&cmd->device->iorequest_cnt);
+ 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:
+ scsi_done(cmd);
+ return 0;
+}
+
+/* Size in bytes of the sg-list stored in the scsi-mq command-private data. */
+static unsigned int scsi_mq_inline_sgl_size(struct Scsi_Host *shost)
+{
+ return min_t(unsigned int, shost->sg_tablesize, SCSI_INLINE_SG_CNT) *
+ sizeof(struct scatterlist);
+}
+
+static blk_status_t scsi_prepare_cmd(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;
+ bool in_flight = test_bit(SCMD_STATE_INFLIGHT, &cmd->state);
+ struct scatterlist *sg;
+
+ scsi_init_command(sdev, cmd);
+
+ cmd->eh_eflags = 0;
+ cmd->prot_type = 0;
+ cmd->prot_flags = 0;
+ cmd->submitter = 0;
+ memset(&cmd->sdb, 0, sizeof(cmd->sdb));
+ cmd->underflow = 0;
+ cmd->transfersize = 0;
+ cmd->host_scribble = NULL;
+ cmd->result = 0;
+ cmd->extra_len = 0;
+ cmd->state = 0;
+ if (in_flight)
+ __set_bit(SCMD_STATE_INFLIGHT, &cmd->state);
+
+ /*
+ * Only clear the driver-private command data if the LLD does not supply
+ * a function to initialize that data.
+ */
+ if (!shost->hostt->init_cmd_priv)
+ memset(cmd + 1, 0, shost->hostt->cmd_size);
+
+ cmd->prot_op = SCSI_PROT_NORMAL;
+ if (blk_rq_bytes(req))
+ cmd->sc_data_direction = rq_dma_dir(req);
+ else
+ cmd->sc_data_direction = DMA_NONE;
+
+ sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
+ cmd->sdb.table.sgl = sg;
+
+ if (scsi_host_get_prot(shost)) {
+ memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
+
+ cmd->prot_sdb->table.sgl =
+ (struct scatterlist *)(cmd->prot_sdb + 1);
+ }
+
+ /*
+ * Special handling for passthrough commands, which don't go to the ULP
+ * at all:
+ */
+ if (blk_rq_is_passthrough(req))
+ return scsi_setup_scsi_cmnd(sdev, req);
+
+ if (sdev->handler && sdev->handler->prep_fn) {
+ blk_status_t ret = sdev->handler->prep_fn(sdev, req);
+
+ if (ret != BLK_STS_OK)
+ return ret;
+ }
+
+ /* Usually overridden by the ULP */
+ cmd->allowed = 0;
+ memset(cmd->cmnd, 0, sizeof(cmd->cmnd));
+ return scsi_cmd_to_driver(cmd)->init_command(cmd);
+}
+
+static void scsi_done_internal(struct scsi_cmnd *cmd, bool complete_directly)
+{
+ struct request *req = scsi_cmd_to_rq(cmd);
+
+ switch (cmd->submitter) {
+ case SUBMITTED_BY_BLOCK_LAYER:
+ break;
+ case SUBMITTED_BY_SCSI_ERROR_HANDLER:
+ return scsi_eh_done(cmd);
+ case SUBMITTED_BY_SCSI_RESET_IOCTL:
+ return;
+ }
+
+ if (unlikely(blk_should_fake_timeout(scsi_cmd_to_rq(cmd)->q)))
+ return;
+ if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state)))
+ return;
+ trace_scsi_dispatch_cmd_done(cmd);
+
+ if (complete_directly)
+ blk_mq_complete_request_direct(req, scsi_complete);
+ else
+ blk_mq_complete_request(req);
+}
+
+void scsi_done(struct scsi_cmnd *cmd)
+{
+ scsi_done_internal(cmd, false);
+}
+EXPORT_SYMBOL(scsi_done);
+
+void scsi_done_direct(struct scsi_cmnd *cmd)
+{
+ scsi_done_internal(cmd, true);
+}
+EXPORT_SYMBOL(scsi_done_direct);
+
+static void scsi_mq_put_budget(struct request_queue *q, int budget_token)
+{
+ struct scsi_device *sdev = q->queuedata;
+
+ sbitmap_put(&sdev->budget_map, budget_token);
+}
+
+/*
+ * 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 int scsi_mq_get_budget(struct request_queue *q)
+{
+ struct scsi_device *sdev = q->queuedata;
+ int token = scsi_dev_queue_ready(q, sdev);
+
+ if (token >= 0)
+ return token;
+
+ atomic_inc(&sdev->restarts);
+
+ /*
+ * Orders atomic_inc(&sdev->restarts) and atomic_read(&sdev->device_busy).
+ * .restarts must be incremented before .device_busy is read because the
+ * code in scsi_run_queue_async() depends on the order of these operations.
+ */
+ smp_mb__after_atomic();
+
+ /*
+ * If all in-flight requests originated from this LUN are completed
+ * before reading .device_busy, sdev->device_busy will be observed as
+ * zero, then blk_mq_delay_run_hw_queues() will dispatch this request
+ * soon. Otherwise, completion of one of these requests will observe
+ * the .restarts flag, and the request queue will be run for handling
+ * this request, see scsi_end_request().
+ */
+ if (unlikely(scsi_device_busy(sdev) == 0 &&
+ !scsi_device_blocked(sdev)))
+ blk_mq_delay_run_hw_queues(sdev->request_queue, SCSI_QUEUE_DELAY);
+ return -1;
+}
+
+static void scsi_mq_set_rq_budget_token(struct request *req, int token)
+{
+ struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
+
+ cmd->budget_token = token;
+}
+
+static int scsi_mq_get_rq_budget_token(struct request *req)
+{
+ struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
+
+ return cmd->budget_token;
+}
+
+static blk_status_t 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);
+ blk_status_t ret;
+ int reason;
+
+ WARN_ON_ONCE(cmd->budget_token < 0);
+
+ /*
+ * If the device is not in running state we will reject some or all
+ * commands.
+ */
+ if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
+ ret = scsi_device_state_check(sdev, req);
+ if (ret != BLK_STS_OK)
+ goto out_put_budget;
+ }
+
+ ret = BLK_STS_RESOURCE;
+ if (!scsi_target_queue_ready(shost, sdev))
+ goto out_put_budget;
+ if (unlikely(scsi_host_in_recovery(shost))) {
+ if (cmd->flags & SCMD_FAIL_IF_RECOVERING)
+ ret = BLK_STS_OFFLINE;
+ goto out_dec_target_busy;
+ }
+ if (!scsi_host_queue_ready(q, shost, sdev, cmd))
+ goto out_dec_target_busy;
+
+ if (!(req->rq_flags & RQF_DONTPREP)) {
+ ret = scsi_prepare_cmd(req);
+ if (ret != BLK_STS_OK)
+ goto out_dec_host_busy;
+ req->rq_flags |= RQF_DONTPREP;
+ } else {
+ clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
+ }
+
+ cmd->flags &= SCMD_PRESERVED_FLAGS;
+ if (sdev->simple_tags)
+ cmd->flags |= SCMD_TAGGED;
+ if (bd->last)
+ cmd->flags |= SCMD_LAST;
+
+ scsi_set_resid(cmd, 0);
+ memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
+ cmd->submitter = SUBMITTED_BY_BLOCK_LAYER;
+
+ blk_mq_start_request(req);
+ reason = scsi_dispatch_cmd(cmd);
+ if (reason) {
+ scsi_set_blocked(cmd, reason);
+ ret = BLK_STS_RESOURCE;
+ goto out_dec_host_busy;
+ }
+
+ return BLK_STS_OK;
+
+out_dec_host_busy:
+ scsi_dec_host_busy(shost, cmd);
+out_dec_target_busy:
+ if (scsi_target(sdev)->can_queue > 0)
+ atomic_dec(&scsi_target(sdev)->target_busy);
+out_put_budget:
+ scsi_mq_put_budget(q, cmd->budget_token);
+ cmd->budget_token = -1;
+ switch (ret) {
+ case BLK_STS_OK:
+ break;
+ case BLK_STS_RESOURCE:
+ case BLK_STS_ZONE_RESOURCE:
+ if (scsi_device_blocked(sdev))
+ ret = BLK_STS_DEV_RESOURCE;
+ break;
+ case BLK_STS_AGAIN:
+ cmd->result = DID_BUS_BUSY << 16;
+ if (req->rq_flags & RQF_DONTPREP)
+ scsi_mq_uninit_cmd(cmd);
+ break;
+ default:
+ if (unlikely(!scsi_device_online(sdev)))
+ cmd->result = DID_NO_CONNECT << 16;
+ else
+ cmd->result = DID_ERROR << 16;
+ /*
+ * Make sure to release all allocated resources when
+ * we hit an error, as we will never see this command
+ * again.
+ */
+ if (req->rq_flags & RQF_DONTPREP)
+ scsi_mq_uninit_cmd(cmd);
+ scsi_run_queue_async(sdev);
+ break;
+ }
+ return ret;
+}
+
+static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
+ unsigned int hctx_idx, unsigned int numa_node)
+{
+ struct Scsi_Host *shost = set->driver_data;
+ struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+ struct scatterlist *sg;
+ int ret = 0;
+
+ cmd->sense_buffer =
+ kmem_cache_alloc_node(scsi_sense_cache, GFP_KERNEL, numa_node);
+ if (!cmd->sense_buffer)
+ return -ENOMEM;
+
+ if (scsi_host_get_prot(shost)) {
+ sg = (void *)cmd + sizeof(struct scsi_cmnd) +
+ shost->hostt->cmd_size;
+ cmd->prot_sdb = (void *)sg + scsi_mq_inline_sgl_size(shost);
+ }
+
+ if (shost->hostt->init_cmd_priv) {
+ ret = shost->hostt->init_cmd_priv(shost, cmd);
+ if (ret < 0)
+ kmem_cache_free(scsi_sense_cache, cmd->sense_buffer);
+ }
+
+ return ret;
+}
+
+static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq,
+ unsigned int hctx_idx)
+{
+ struct Scsi_Host *shost = set->driver_data;
+ struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
+
+ if (shost->hostt->exit_cmd_priv)
+ shost->hostt->exit_cmd_priv(shost, cmd);
+ kmem_cache_free(scsi_sense_cache, cmd->sense_buffer);
+}
+
+
+static int scsi_mq_poll(struct blk_mq_hw_ctx *hctx, struct io_comp_batch *iob)
+{
+ struct Scsi_Host *shost = hctx->driver_data;
+
+ if (shost->hostt->mq_poll)
+ return shost->hostt->mq_poll(shost, hctx->queue_num);
+
+ return 0;
+}
+
+static int scsi_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
+ unsigned int hctx_idx)
+{
+ struct Scsi_Host *shost = data;
+
+ hctx->driver_data = shost;
+ return 0;
+}
+
+static void scsi_map_queues(struct blk_mq_tag_set *set)
+{
+ struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
+
+ if (shost->hostt->map_queues)
+ return shost->hostt->map_queues(shost);
+ blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
+}
+
+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,
+ SG_MAX_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_segment_boundary(q, shost->dma_boundary);
+ dma_set_seg_boundary(dev, shost->dma_boundary);
+
+ blk_queue_max_segment_size(q, shost->max_segment_size);
+ blk_queue_virt_boundary(q, shost->virt_boundary_mask);
+ dma_set_max_seg_size(dev, queue_max_segment_size(q));
+
+ /*
+ * Set a reasonable default alignment: The larger of 32-byte (dword),
+ * which is a common minimum for HBAs, and the minimum DMA alignment,
+ * which is set by the platform.
+ *
+ * Devices that require a bigger alignment can increase it later.
+ */
+ blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1);
+}
+EXPORT_SYMBOL_GPL(__scsi_init_queue);
+
+static const struct blk_mq_ops scsi_mq_ops_no_commit = {
+ .get_budget = scsi_mq_get_budget,
+ .put_budget = scsi_mq_put_budget,
+ .queue_rq = scsi_queue_rq,
+ .complete = scsi_complete,
+ .timeout = scsi_timeout,
+#ifdef CONFIG_BLK_DEBUG_FS
+ .show_rq = scsi_show_rq,
+#endif
+ .init_request = scsi_mq_init_request,
+ .exit_request = scsi_mq_exit_request,
+ .cleanup_rq = scsi_cleanup_rq,
+ .busy = scsi_mq_lld_busy,
+ .map_queues = scsi_map_queues,
+ .init_hctx = scsi_init_hctx,
+ .poll = scsi_mq_poll,
+ .set_rq_budget_token = scsi_mq_set_rq_budget_token,
+ .get_rq_budget_token = scsi_mq_get_rq_budget_token,
+};
+
+
+static void scsi_commit_rqs(struct blk_mq_hw_ctx *hctx)
+{
+ struct Scsi_Host *shost = hctx->driver_data;
+
+ shost->hostt->commit_rqs(shost, hctx->queue_num);
+}
+
+static const struct blk_mq_ops scsi_mq_ops = {
+ .get_budget = scsi_mq_get_budget,
+ .put_budget = scsi_mq_put_budget,
+ .queue_rq = scsi_queue_rq,
+ .commit_rqs = scsi_commit_rqs,
+ .complete = scsi_complete,
+ .timeout = scsi_timeout,
+#ifdef CONFIG_BLK_DEBUG_FS
+ .show_rq = scsi_show_rq,
+#endif
+ .init_request = scsi_mq_init_request,
+ .exit_request = scsi_mq_exit_request,
+ .cleanup_rq = scsi_cleanup_rq,
+ .busy = scsi_mq_lld_busy,
+ .map_queues = scsi_map_queues,
+ .init_hctx = scsi_init_hctx,
+ .poll = scsi_mq_poll,
+ .set_rq_budget_token = scsi_mq_set_rq_budget_token,
+ .get_rq_budget_token = scsi_mq_get_rq_budget_token,
+};
+
+int scsi_mq_setup_tags(struct Scsi_Host *shost)
+{
+ unsigned int cmd_size, sgl_size;
+ struct blk_mq_tag_set *tag_set = &shost->tag_set;
+
+ sgl_size = max_t(unsigned int, sizeof(struct scatterlist),
+ scsi_mq_inline_sgl_size(shost));
+ 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) +
+ sizeof(struct scatterlist) * SCSI_INLINE_PROT_SG_CNT;
+
+ memset(tag_set, 0, sizeof(*tag_set));
+ if (shost->hostt->commit_rqs)
+ tag_set->ops = &scsi_mq_ops;
+ else
+ tag_set->ops = &scsi_mq_ops_no_commit;
+ tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1;
+ tag_set->nr_maps = shost->nr_maps ? : 1;
+ tag_set->queue_depth = shost->can_queue;
+ tag_set->cmd_size = cmd_size;
+ tag_set->numa_node = dev_to_node(shost->dma_dev);
+ tag_set->flags = BLK_MQ_F_SHOULD_MERGE;
+ tag_set->flags |=
+ BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
+ if (shost->queuecommand_may_block)
+ tag_set->flags |= BLK_MQ_F_BLOCKING;
+ tag_set->driver_data = shost;
+ if (shost->host_tagset)
+ tag_set->flags |= BLK_MQ_F_TAG_HCTX_SHARED;
+
+ return blk_mq_alloc_tag_set(tag_set);
+}
+
+void scsi_mq_free_tags(struct kref *kref)
+{
+ struct Scsi_Host *shost = container_of(kref, typeof(*shost),
+ tagset_refcnt);
+
+ blk_mq_free_tag_set(&shost->tag_set);
+ complete(&shost->tagset_freed);
+}
+
+/**
+ * scsi_device_from_queue - return sdev associated with a request_queue
+ * @q: The request queue to return the sdev from
+ *
+ * Return the sdev associated with a request queue or NULL if the
+ * request_queue does not reference a SCSI device.
+ */
+struct scsi_device *scsi_device_from_queue(struct request_queue *q)
+{
+ struct scsi_device *sdev = NULL;
+
+ if (q->mq_ops == &scsi_mq_ops_no_commit ||
+ q->mq_ops == &scsi_mq_ops)
+ sdev = q->queuedata;
+ if (!sdev || !get_device(&sdev->sdev_gendev))
+ sdev = NULL;
+
+ return sdev;
+}
+/*
+ * pktcdvd should have been integrated into the SCSI layers, but for historical
+ * reasons like the old IDE driver it isn't. This export allows it to safely
+ * probe if a given device is a SCSI one and only attach to that.
+ */
+#ifdef CONFIG_CDROM_PKTCDVD_MODULE
+EXPORT_SYMBOL_GPL(scsi_device_from_queue);
+#endif
+
+/**
+ * scsi_block_requests - Utility function used by low-level drivers to prevent
+ * further commands from being queued to the device.
+ * @shost: host in question
+ *
+ * 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);
+
+/**
+ * scsi_unblock_requests - Utility function used by low-level drivers to allow
+ * further commands to be queued to the device.
+ * @shost: host in question
+ *
+ * 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);
+
+void scsi_exit_queue(void)
+{
+ kmem_cache_destroy(scsi_sense_cache);
+}
+
+/**
+ * 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)
+ * @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,
+ 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;
+ const struct scsi_exec_args exec_args = {
+ .sshdr = sshdr,
+ };
+ int ret;
+
+ memset(cmd, 0, sizeof(cmd));
+ cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
+
+ /*
+ * Use MODE SELECT(10) if the device asked for it or if the mode page
+ * and the mode select header cannot fit within the maximumm 255 bytes
+ * of the MODE SELECT(6) command.
+ */
+ if (sdev->use_10_for_ms ||
+ len + 4 > 255 ||
+ data->block_descriptor_length > 255) {
+ if (len > 65535 - 8)
+ 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;
+ put_unaligned_be16(data->block_descriptor_length,
+ &real_buffer[6]);
+
+ cmd[0] = MODE_SELECT_10;
+ put_unaligned_be16(len, &cmd[7]);
+ } else {
+ if (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_cmd(sdev, cmd, REQ_OP_DRV_OUT, real_buffer, len,
+ timeout, retries, &exec_args);
+ 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 to prevent mode sense from returning block descriptors
+ * @modepage: mode page being requested
+ * @subpage: sub-page of the 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, or a negative error number on failure
+ */
+int
+scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage, int subpage,
+ 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, retry_count = retries;
+ struct scsi_sense_hdr my_sshdr;
+ const struct scsi_exec_args exec_args = {
+ /* caller might not be interested in sense, but we need it */
+ .sshdr = sshdr ? : &my_sshdr,
+ };
+
+ memset(data, 0, sizeof(*data));
+ memset(&cmd[0], 0, 12);
+
+ dbd = sdev->set_dbd_for_ms ? 8 : dbd;
+ cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
+ cmd[2] = modepage;
+ cmd[3] = subpage;
+
+ sshdr = exec_args.sshdr;
+
+ retry:
+ use_10_for_ms = sdev->use_10_for_ms || len > 255;
+
+ if (use_10_for_ms) {
+ if (len < 8 || len > 65535)
+ return -EINVAL;
+
+ cmd[0] = MODE_SENSE_10;
+ put_unaligned_be16(len, &cmd[7]);
+ header_length = 8;
+ } else {
+ if (len < 4)
+ return -EINVAL;
+
+ cmd[0] = MODE_SENSE;
+ cmd[4] = len;
+ header_length = 4;
+ }
+
+ memset(buffer, 0, len);
+
+ result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, buffer, len,
+ timeout, retries, &exec_args);
+ if (result < 0)
+ return result;
+
+ /* 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 (!scsi_status_is_good(result)) {
+ if (scsi_sense_valid(sshdr)) {
+ if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
+ (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
+ /*
+ * Invalid command operation code: retry using
+ * MODE SENSE(6) if this was a MODE SENSE(10)
+ * request, except if the request mode page is
+ * too large for MODE SENSE single byte
+ * allocation length field.
+ */
+ if (use_10_for_ms) {
+ if (len > 255)
+ return -EIO;
+ sdev->use_10_for_ms = 0;
+ goto retry;
+ }
+ }
+ if (scsi_status_is_check_condition(result) &&
+ sshdr->sense_key == UNIT_ATTENTION &&
+ retry_count) {
+ retry_count--;
+ goto retry;
+ }
+ }
+ return -EIO;
+ }
+ 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 = get_unaligned_be16(&buffer[0]) + 2;
+ data->medium_type = buffer[2];
+ data->device_specific = buffer[3];
+ data->longlba = buffer[4] & 0x01;
+ data->block_descriptor_length = get_unaligned_be16(&buffer[6]);
+ } 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 0;
+}
+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: outpout pointer for decoded sense information.
+ *
+ * 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)
+{
+ char cmd[] = {
+ TEST_UNIT_READY, 0, 0, 0, 0, 0,
+ };
+ const struct scsi_exec_args exec_args = {
+ .sshdr = sshdr,
+ };
+ int result;
+
+ /* try to eat the UNIT_ATTENTION if there are enough retries */
+ do {
+ result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, NULL, 0,
+ timeout, 1, &exec_args);
+ 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);
+
+ 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 successful 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:
+ case SDEV_QUIESCE:
+ case SDEV_OFFLINE:
+ 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:
+ 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_BLOCK:
+ case SDEV_CREATED_BLOCK:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
+
+ }
+ sdev->offline_already = false;
+ 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);
+
+/**
+ * scsi_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:
+ scsi_rescan_device(sdev);
+ 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;
+ case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
+ envp[idx++] = "SDEV_UA=ASYMMETRIC_ACCESS_STATE_CHANGED";
+ break;
+ case SDEV_EVT_POWER_ON_RESET_OCCURRED:
+ envp[idx++] = "SDEV_UA=POWER_ON_RESET_OCCURRED";
+ break;
+ default:
+ /* do nothing */
+ break;
+ }
+
+ envp[idx++] = NULL;
+
+ kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
+}
+
+/**
+ * scsi_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:
+ case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
+ case SDEV_EVT_POWER_ON_RESET_OCCURRED:
+ 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 all commands except power management.
+ * @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 power management requests will be accepted, all others will
+ * be deferred.
+ *
+ * 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)
+{
+ struct request_queue *q = sdev->request_queue;
+ int err;
+
+ /*
+ * It is allowed to call scsi_device_quiesce() multiple times from
+ * the same context but concurrent scsi_device_quiesce() calls are
+ * not allowed.
+ */
+ WARN_ON_ONCE(sdev->quiesced_by && sdev->quiesced_by != current);
+
+ if (sdev->quiesced_by == current)
+ return 0;
+
+ blk_set_pm_only(q);
+
+ blk_mq_freeze_queue(q);
+ /*
+ * Ensure that the effect of blk_set_pm_only() will be visible
+ * for percpu_ref_tryget() callers that occur after the queue
+ * unfreeze even if the queue was already frozen before this function
+ * was called. See also https://lwn.net/Articles/573497/.
+ */
+ synchronize_rcu();
+ blk_mq_unfreeze_queue(q);
+
+ mutex_lock(&sdev->state_mutex);
+ err = scsi_device_set_state(sdev, SDEV_QUIESCE);
+ if (err == 0)
+ sdev->quiesced_by = current;
+ else
+ blk_clear_pm_only(q);
+ mutex_unlock(&sdev->state_mutex);
+
+ return err;
+}
+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)
+ */
+ mutex_lock(&sdev->state_mutex);
+ if (sdev->sdev_state == SDEV_QUIESCE)
+ scsi_device_set_state(sdev, SDEV_RUNNING);
+ if (sdev->quiesced_by) {
+ sdev->quiesced_by = NULL;
+ blk_clear_pm_only(sdev->request_queue);
+ }
+ mutex_unlock(&sdev->state_mutex);
+}
+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);
+
+static int __scsi_internal_device_block_nowait(struct scsi_device *sdev)
+{
+ if (scsi_device_set_state(sdev, SDEV_BLOCK))
+ return scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
+
+ return 0;
+}
+
+void scsi_start_queue(struct scsi_device *sdev)
+{
+ if (cmpxchg(&sdev->queue_stopped, 1, 0))
+ blk_mq_unquiesce_queue(sdev->request_queue);
+}
+
+static void scsi_stop_queue(struct scsi_device *sdev)
+{
+ /*
+ * The atomic variable of ->queue_stopped covers that
+ * blk_mq_quiesce_queue* is balanced with blk_mq_unquiesce_queue.
+ *
+ * The caller needs to wait until quiesce is done.
+ */
+ if (!cmpxchg(&sdev->queue_stopped, 0, 1))
+ blk_mq_quiesce_queue_nowait(sdev->request_queue);
+}
+
+/**
+ * scsi_internal_device_block_nowait - try to transition to the SDEV_BLOCK state
+ * @sdev: device to block
+ *
+ * Pause SCSI command processing on the specified device. Does not sleep.
+ *
+ * Returns zero if successful or a negative error code upon failure.
+ *
+ * Notes:
+ * This routine transitions the device to the SDEV_BLOCK state (which must be
+ * a legal transition). When the device is in this state, command processing
+ * is paused until the device leaves the SDEV_BLOCK state. See also
+ * scsi_internal_device_unblock_nowait().
+ */
+int scsi_internal_device_block_nowait(struct scsi_device *sdev)
+{
+ int ret = __scsi_internal_device_block_nowait(sdev);
+
+ /*
+ * The device has transitioned to SDEV_BLOCK. Stop the
+ * block layer from calling the midlayer with this device's
+ * request queue.
+ */
+ if (!ret)
+ scsi_stop_queue(sdev);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait);
+
+/**
+ * scsi_device_block - try to transition to the SDEV_BLOCK state
+ * @sdev: device to block
+ * @data: dummy argument, ignored
+ *
+ * Pause SCSI command processing on the specified device. Callers must wait
+ * until all ongoing scsi_queue_rq() calls have finished after this function
+ * returns.
+ *
+ * Note:
+ * This routine transitions the device to the SDEV_BLOCK state (which must be
+ * a legal transition). When the device is in this state, command processing
+ * is paused until the device leaves the SDEV_BLOCK state. See also
+ * scsi_internal_device_unblock().
+ */
+static void scsi_device_block(struct scsi_device *sdev, void *data)
+{
+ int err;
+ enum scsi_device_state state;
+
+ mutex_lock(&sdev->state_mutex);
+ err = __scsi_internal_device_block_nowait(sdev);
+ state = sdev->sdev_state;
+ if (err == 0)
+ /*
+ * scsi_stop_queue() must be called with the state_mutex
+ * held. Otherwise a simultaneous scsi_start_queue() call
+ * might unquiesce the queue before we quiesce it.
+ */
+ scsi_stop_queue(sdev);
+
+ mutex_unlock(&sdev->state_mutex);
+
+ WARN_ONCE(err, "%s: failed to block %s in state %d\n",
+ __func__, dev_name(&sdev->sdev_gendev), state);
+}
+
+/**
+ * scsi_internal_device_unblock_nowait - resume a device after a block request
+ * @sdev: device to resume
+ * @new_state: state to set the device to after unblocking
+ *
+ * Restart the device queue for a previously suspended SCSI device. Does not
+ * sleep.
+ *
+ * Returns zero if successful or a negative error code upon failure.
+ *
+ * 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_nowait(struct scsi_device *sdev,
+ enum scsi_device_state new_state)
+{
+ switch (new_state) {
+ case SDEV_RUNNING:
+ case SDEV_TRANSPORT_OFFLINE:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /*
+ * Try to transition the scsi device to SDEV_RUNNING or one of the
+ * offlined states and goose the device queue if successful.
+ */
+ switch (sdev->sdev_state) {
+ case SDEV_BLOCK:
+ case SDEV_TRANSPORT_OFFLINE:
+ sdev->sdev_state = new_state;
+ break;
+ case SDEV_CREATED_BLOCK:
+ if (new_state == SDEV_TRANSPORT_OFFLINE ||
+ new_state == SDEV_OFFLINE)
+ sdev->sdev_state = new_state;
+ else
+ sdev->sdev_state = SDEV_CREATED;
+ break;
+ case SDEV_CANCEL:
+ case SDEV_OFFLINE:
+ break;
+ default:
+ return -EINVAL;
+ }
+ scsi_start_queue(sdev);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(scsi_internal_device_unblock_nowait);
+
+/**
+ * scsi_internal_device_unblock - resume a device after a block request
+ * @sdev: device to resume
+ * @new_state: state to set the device to after unblocking
+ *
+ * Restart the device queue for a previously suspended SCSI device. May sleep.
+ *
+ * Returns zero if successful or a negative error code upon failure.
+ *
+ * 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.
+ */
+static int scsi_internal_device_unblock(struct scsi_device *sdev,
+ enum scsi_device_state new_state)
+{
+ int ret;
+
+ mutex_lock(&sdev->state_mutex);
+ ret = scsi_internal_device_unblock_nowait(sdev, new_state);
+ mutex_unlock(&sdev->state_mutex);
+
+ return ret;
+}
+
+static int
+target_block(struct device *dev, void *data)
+{
+ if (scsi_is_target_device(dev))
+ starget_for_each_device(to_scsi_target(dev), NULL,
+ scsi_device_block);
+ return 0;
+}
+
+/**
+ * scsi_block_targets - transition all SCSI child devices to SDEV_BLOCK state
+ * @dev: a parent device of one or more scsi_target devices
+ * @shost: the Scsi_Host to which this device belongs
+ *
+ * Iterate over all children of @dev, which should be scsi_target devices,
+ * and switch all subordinate scsi devices to SDEV_BLOCK state. Wait for
+ * ongoing scsi_queue_rq() calls to finish. May sleep.
+ *
+ * Note:
+ * @dev must not itself be a scsi_target device.
+ */
+void
+scsi_block_targets(struct Scsi_Host *shost, struct device *dev)
+{
+ WARN_ON_ONCE(scsi_is_target_device(dev));
+ device_for_each_child(dev, NULL, target_block);
+ blk_mq_wait_quiesce_done(&shost->tag_set);
+}
+EXPORT_SYMBOL_GPL(scsi_block_targets);
+
+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_host_block - Try to transition all logical units to the SDEV_BLOCK state
+ * @shost: device to block
+ *
+ * Pause SCSI command processing for all logical units associated with the SCSI
+ * host and wait until pending scsi_queue_rq() calls have finished.
+ *
+ * Returns zero if successful or a negative error code upon failure.
+ */
+int
+scsi_host_block(struct Scsi_Host *shost)
+{
+ struct scsi_device *sdev;
+ int ret;
+
+ /*
+ * Call scsi_internal_device_block_nowait so we can avoid
+ * calling synchronize_rcu() for each LUN.
+ */
+ shost_for_each_device(sdev, shost) {
+ mutex_lock(&sdev->state_mutex);
+ ret = scsi_internal_device_block_nowait(sdev);
+ mutex_unlock(&sdev->state_mutex);
+ if (ret) {
+ scsi_device_put(sdev);
+ return ret;
+ }
+ }
+
+ /* Wait for ongoing scsi_queue_rq() calls to finish. */
+ blk_mq_wait_quiesce_done(&shost->tag_set);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(scsi_host_block);
+
+int
+scsi_host_unblock(struct Scsi_Host *shost, int new_state)
+{
+ struct scsi_device *sdev;
+ int ret = 0;
+
+ shost_for_each_device(sdev, shost) {
+ ret = scsi_internal_device_unblock(sdev, new_state);
+ if (ret) {
+ scsi_device_put(sdev);
+ break;
+ }
+ }
+ return ret;
+}
+EXPORT_SYMBOL_GPL(scsi_host_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);
+
+static unsigned char designator_prio(const unsigned char *d)
+{
+ if (d[1] & 0x30)
+ /* not associated with LUN */
+ return 0;
+
+ if (d[3] == 0)
+ /* invalid length */
+ return 0;
+
+ /*
+ * Order of preference for lun descriptor:
+ * - SCSI name string
+ * - NAA IEEE Registered Extended
+ * - EUI-64 based 16-byte
+ * - EUI-64 based 12-byte
+ * - NAA IEEE Registered
+ * - NAA IEEE Extended
+ * - EUI-64 based 8-byte
+ * - SCSI name string (truncated)
+ * - T10 Vendor ID
+ * as longer descriptors reduce the likelyhood
+ * of identification clashes.
+ */
+
+ switch (d[1] & 0xf) {
+ case 8:
+ /* SCSI name string, variable-length UTF-8 */
+ return 9;
+ case 3:
+ switch (d[4] >> 4) {
+ case 6:
+ /* NAA registered extended */
+ return 8;
+ case 5:
+ /* NAA registered */
+ return 5;
+ case 4:
+ /* NAA extended */
+ return 4;
+ case 3:
+ /* NAA locally assigned */
+ return 1;
+ default:
+ break;
+ }
+ break;
+ case 2:
+ switch (d[3]) {
+ case 16:
+ /* EUI64-based, 16 byte */
+ return 7;
+ case 12:
+ /* EUI64-based, 12 byte */
+ return 6;
+ case 8:
+ /* EUI64-based, 8 byte */
+ return 3;
+ default:
+ break;
+ }
+ break;
+ case 1:
+ /* T10 vendor ID */
+ return 1;
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+/**
+ * scsi_vpd_lun_id - return a unique device identification
+ * @sdev: SCSI device
+ * @id: buffer for the identification
+ * @id_len: length of the buffer
+ *
+ * Copies a unique device identification into @id based
+ * on the information in the VPD page 0x83 of the device.
+ * The string will be formatted as a SCSI name string.
+ *
+ * Returns the length of the identification or error on failure.
+ * If the identifier is longer than the supplied buffer the actual
+ * identifier length is returned and the buffer is not zero-padded.
+ */
+int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
+{
+ u8 cur_id_prio = 0;
+ u8 cur_id_size = 0;
+ const unsigned char *d, *cur_id_str;
+ const struct scsi_vpd *vpd_pg83;
+ int id_size = -EINVAL;
+
+ rcu_read_lock();
+ vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
+ if (!vpd_pg83) {
+ rcu_read_unlock();
+ return -ENXIO;
+ }
+
+ /* The id string must be at least 20 bytes + terminating NULL byte */
+ if (id_len < 21) {
+ rcu_read_unlock();
+ return -EINVAL;
+ }
+
+ memset(id, 0, id_len);
+ for (d = vpd_pg83->data + 4;
+ d < vpd_pg83->data + vpd_pg83->len;
+ d += d[3] + 4) {
+ u8 prio = designator_prio(d);
+
+ if (prio == 0 || cur_id_prio > prio)
+ continue;
+
+ switch (d[1] & 0xf) {
+ case 0x1:
+ /* T10 Vendor ID */
+ if (cur_id_size > d[3])
+ break;
+ cur_id_prio = prio;
+ cur_id_size = d[3];
+ if (cur_id_size + 4 > id_len)
+ cur_id_size = id_len - 4;
+ cur_id_str = d + 4;
+ id_size = snprintf(id, id_len, "t10.%*pE",
+ cur_id_size, cur_id_str);
+ break;
+ case 0x2:
+ /* EUI-64 */
+ cur_id_prio = prio;
+ cur_id_size = d[3];
+ cur_id_str = d + 4;
+ switch (cur_id_size) {
+ case 8:
+ id_size = snprintf(id, id_len,
+ "eui.%8phN",
+ cur_id_str);
+ break;
+ case 12:
+ id_size = snprintf(id, id_len,
+ "eui.%12phN",
+ cur_id_str);
+ break;
+ case 16:
+ id_size = snprintf(id, id_len,
+ "eui.%16phN",
+ cur_id_str);
+ break;
+ default:
+ break;
+ }
+ break;
+ case 0x3:
+ /* NAA */
+ cur_id_prio = prio;
+ cur_id_size = d[3];
+ cur_id_str = d + 4;
+ switch (cur_id_size) {
+ case 8:
+ id_size = snprintf(id, id_len,
+ "naa.%8phN",
+ cur_id_str);
+ break;
+ case 16:
+ id_size = snprintf(id, id_len,
+ "naa.%16phN",
+ cur_id_str);
+ break;
+ default:
+ break;
+ }
+ break;
+ case 0x8:
+ /* SCSI name string */
+ if (cur_id_size > d[3])
+ break;
+ /* Prefer others for truncated descriptor */
+ if (d[3] > id_len) {
+ prio = 2;
+ if (cur_id_prio > prio)
+ break;
+ }
+ cur_id_prio = prio;
+ cur_id_size = id_size = d[3];
+ cur_id_str = d + 4;
+ if (cur_id_size >= id_len)
+ cur_id_size = id_len - 1;
+ memcpy(id, cur_id_str, cur_id_size);
+ break;
+ default:
+ break;
+ }
+ }
+ rcu_read_unlock();
+
+ return id_size;
+}
+EXPORT_SYMBOL(scsi_vpd_lun_id);
+
+/*
+ * scsi_vpd_tpg_id - return a target port group identifier
+ * @sdev: SCSI device
+ *
+ * Returns the Target Port Group identifier from the information
+ * froom VPD page 0x83 of the device.
+ *
+ * Returns the identifier or error on failure.
+ */
+int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
+{
+ const unsigned char *d;
+ const struct scsi_vpd *vpd_pg83;
+ int group_id = -EAGAIN, rel_port = -1;
+
+ rcu_read_lock();
+ vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
+ if (!vpd_pg83) {
+ rcu_read_unlock();
+ return -ENXIO;
+ }
+
+ d = vpd_pg83->data + 4;
+ while (d < vpd_pg83->data + vpd_pg83->len) {
+ switch (d[1] & 0xf) {
+ case 0x4:
+ /* Relative target port */
+ rel_port = get_unaligned_be16(&d[6]);
+ break;
+ case 0x5:
+ /* Target port group */
+ group_id = get_unaligned_be16(&d[6]);
+ break;
+ default:
+ break;
+ }
+ d += d[3] + 4;
+ }
+ rcu_read_unlock();
+
+ if (group_id >= 0 && rel_id && rel_port != -1)
+ *rel_id = rel_port;
+
+ return group_id;
+}
+EXPORT_SYMBOL(scsi_vpd_tpg_id);
+
+/**
+ * scsi_build_sense - build sense data for a command
+ * @scmd: scsi command for which the sense should be formatted
+ * @desc: Sense format (non-zero == descriptor format,
+ * 0 == fixed format)
+ * @key: Sense key
+ * @asc: Additional sense code
+ * @ascq: Additional sense code qualifier
+ *
+ **/
+void scsi_build_sense(struct scsi_cmnd *scmd, int desc, u8 key, u8 asc, u8 ascq)
+{
+ scsi_build_sense_buffer(desc, scmd->sense_buffer, key, asc, ascq);
+ scmd->result = SAM_STAT_CHECK_CONDITION;
+}
+EXPORT_SYMBOL_GPL(scsi_build_sense);