Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
new file mode 100644
index 0000000..7cbc412
--- /dev/null
+++ b/drivers/scsi/scsi_lib.c
@@ -0,0 +1,2023 @@
+/*
+ * scsi_lib.c Copyright (C) 1999 Eric Youngdale
+ *
+ * SCSI queueing library.
+ * Initial versions: Eric Youngdale (eric@andante.org).
+ * Based upon conversations with large numbers
+ * of people at Linux Expo.
+ */
+
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/completion.h>
+#include <linux/kernel.h>
+#include <linux/mempool.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/delay.h>
+
+#include <scsi/scsi.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_request.h>
+
+#include "scsi_priv.h"
+#include "scsi_logging.h"
+
+
+#define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))
+#define SG_MEMPOOL_SIZE 32
+
+struct scsi_host_sg_pool {
+ size_t size;
+ char *name;
+ kmem_cache_t *slab;
+ mempool_t *pool;
+};
+
+#if (SCSI_MAX_PHYS_SEGMENTS < 32)
+#error SCSI_MAX_PHYS_SEGMENTS is too small
+#endif
+
+#define SP(x) { x, "sgpool-" #x }
+struct scsi_host_sg_pool scsi_sg_pools[] = {
+ SP(8),
+ SP(16),
+ SP(32),
+#if (SCSI_MAX_PHYS_SEGMENTS > 32)
+ SP(64),
+#if (SCSI_MAX_PHYS_SEGMENTS > 64)
+ SP(128),
+#if (SCSI_MAX_PHYS_SEGMENTS > 128)
+ SP(256),
+#if (SCSI_MAX_PHYS_SEGMENTS > 256)
+#error SCSI_MAX_PHYS_SEGMENTS is too large
+#endif
+#endif
+#endif
+#endif
+};
+#undef SP
+
+
+/*
+ * Function: scsi_insert_special_req()
+ *
+ * Purpose: Insert pre-formed request into request queue.
+ *
+ * Arguments: sreq - request that is ready to be queued.
+ * at_head - boolean. True if we should insert at head
+ * of queue, false if we should insert at tail.
+ *
+ * Lock status: Assumed that lock is not held upon entry.
+ *
+ * Returns: Nothing
+ *
+ * Notes: This function is called from character device and from
+ * ioctl types of functions where the caller knows exactly
+ * what SCSI command needs to be issued. The idea is that
+ * we merely inject the command into the queue (at the head
+ * for now), and then call the queue request function to actually
+ * process it.
+ */
+int scsi_insert_special_req(struct scsi_request *sreq, int at_head)
+{
+ /*
+ * Because users of this function are apt to reuse requests with no
+ * modification, we have to sanitise the request flags here
+ */
+ sreq->sr_request->flags &= ~REQ_DONTPREP;
+ blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
+ at_head, sreq, 0);
+ return 0;
+}
+
+/*
+ * Function: scsi_queue_insert()
+ *
+ * Purpose: Insert a command in the midlevel queue.
+ *
+ * Arguments: cmd - command that we are adding to queue.
+ * reason - why we are inserting command to queue.
+ *
+ * Lock status: Assumed that lock is not held upon entry.
+ *
+ * Returns: Nothing.
+ *
+ * Notes: We do this for one of two cases. Either the host is busy
+ * and it cannot accept any more commands for the time being,
+ * or the device returned QUEUE_FULL and can accept no more
+ * commands.
+ * Notes: This could be called either from an interrupt context or a
+ * normal process context.
+ */
+int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
+{
+ struct Scsi_Host *host = cmd->device->host;
+ struct scsi_device *device = cmd->device;
+
+ SCSI_LOG_MLQUEUE(1,
+ printk("Inserting command %p into mlqueue\n", cmd));
+
+ /*
+ * We are inserting the command into the ml queue. First, we
+ * cancel the timer, so it doesn't time out.
+ */
+ scsi_delete_timer(cmd);
+
+ /*
+ * Next, set the appropriate busy bit for the device/host.
+ *
+ * If the host/device isn't busy, assume that something actually
+ * completed, and that we should be able to queue a command now.
+ *
+ * Note that the prior mid-layer assumption that any host could
+ * always queue at least one command is now broken. The mid-layer
+ * will implement a user specifiable stall (see
+ * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
+ * if a command is requeued with no other commands outstanding
+ * either for the device or for the host.
+ */
+ if (reason == SCSI_MLQUEUE_HOST_BUSY)
+ host->host_blocked = host->max_host_blocked;
+ else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
+ device->device_blocked = device->max_device_blocked;
+
+ /*
+ * Register the fact that we own the thing for now.
+ */
+ cmd->state = SCSI_STATE_MLQUEUE;
+ cmd->owner = SCSI_OWNER_MIDLEVEL;
+
+ /*
+ * Decrement the counters, since these commands are no longer
+ * active on the host/device.
+ */
+ scsi_device_unbusy(device);
+
+ /*
+ * Insert this command at the head of the queue for it's device.
+ * It will go before all other commands that are already in the queue.
+ *
+ * NOTE: there is magic here about the way the queue is plugged if
+ * we have no outstanding commands.
+ *
+ * Although this *doesn't* plug the queue, it does call the request
+ * function. The SCSI request function detects the blocked condition
+ * and plugs the queue appropriately.
+ */
+ blk_insert_request(device->request_queue, cmd->request, 1, cmd, 1);
+ return 0;
+}
+
+/*
+ * Function: scsi_do_req
+ *
+ * Purpose: Queue a SCSI request
+ *
+ * Arguments: sreq - command descriptor.
+ * cmnd - actual SCSI command to be performed.
+ * buffer - data buffer.
+ * bufflen - size of data buffer.
+ * done - completion function to be run.
+ * timeout - how long to let it run before timeout.
+ * retries - number of retries we allow.
+ *
+ * Lock status: No locks held upon entry.
+ *
+ * Returns: Nothing.
+ *
+ * Notes: This function is only used for queueing requests for things
+ * like ioctls and character device requests - this is because
+ * we essentially just inject a request into the queue for the
+ * device.
+ *
+ * In order to support the scsi_device_quiesce function, we
+ * now inject requests on the *head* of the device queue
+ * rather than the tail.
+ */
+void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
+ void *buffer, unsigned bufflen,
+ void (*done)(struct scsi_cmnd *),
+ int timeout, int retries)
+{
+ /*
+ * If the upper level driver is reusing these things, then
+ * we should release the low-level block now. Another one will
+ * be allocated later when this request is getting queued.
+ */
+ __scsi_release_request(sreq);
+
+ /*
+ * Our own function scsi_done (which marks the host as not busy,
+ * disables the timeout counter, etc) will be called by us or by the
+ * scsi_hosts[host].queuecommand() function needs to also call
+ * the completion function for the high level driver.
+ */
+ memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
+ sreq->sr_bufflen = bufflen;
+ sreq->sr_buffer = buffer;
+ sreq->sr_allowed = retries;
+ sreq->sr_done = done;
+ sreq->sr_timeout_per_command = timeout;
+
+ if (sreq->sr_cmd_len == 0)
+ sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
+
+ /*
+ * head injection *required* here otherwise quiesce won't work
+ */
+ scsi_insert_special_req(sreq, 1);
+}
+EXPORT_SYMBOL(scsi_do_req);
+
+static void scsi_wait_done(struct scsi_cmnd *cmd)
+{
+ struct request *req = cmd->request;
+ struct request_queue *q = cmd->device->request_queue;
+ unsigned long flags;
+
+ req->rq_status = RQ_SCSI_DONE; /* Busy, but indicate request done */
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ if (blk_rq_tagged(req))
+ blk_queue_end_tag(q, req);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ if (req->waiting)
+ complete(req->waiting);
+}
+
+/* This is the end routine we get to if a command was never attached
+ * to the request. Simply complete the request without changing
+ * rq_status; this will cause a DRIVER_ERROR. */
+static void scsi_wait_req_end_io(struct request *req)
+{
+ BUG_ON(!req->waiting);
+
+ complete(req->waiting);
+}
+
+void scsi_wait_req(struct scsi_request *sreq, const void *cmnd, void *buffer,
+ unsigned bufflen, int timeout, int retries)
+{
+ DECLARE_COMPLETION(wait);
+
+ sreq->sr_request->waiting = &wait;
+ sreq->sr_request->rq_status = RQ_SCSI_BUSY;
+ sreq->sr_request->end_io = scsi_wait_req_end_io;
+ scsi_do_req(sreq, cmnd, buffer, bufflen, scsi_wait_done,
+ timeout, retries);
+ wait_for_completion(&wait);
+ sreq->sr_request->waiting = NULL;
+ if (sreq->sr_request->rq_status != RQ_SCSI_DONE)
+ sreq->sr_result |= (DRIVER_ERROR << 24);
+
+ __scsi_release_request(sreq);
+}
+EXPORT_SYMBOL(scsi_wait_req);
+
+/*
+ * Function: scsi_init_cmd_errh()
+ *
+ * Purpose: Initialize cmd fields related to error handling.
+ *
+ * Arguments: cmd - command that is ready to be queued.
+ *
+ * Returns: Nothing
+ *
+ * Notes: This function has the job of initializing a number of
+ * fields related to error handling. Typically this will
+ * be called once for each command, as required.
+ */
+static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
+{
+ cmd->owner = SCSI_OWNER_MIDLEVEL;
+ cmd->serial_number = 0;
+ cmd->serial_number_at_timeout = 0;
+ cmd->abort_reason = 0;
+
+ memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
+
+ if (cmd->cmd_len == 0)
+ cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
+
+ /*
+ * We need saved copies of a number of fields - this is because
+ * error handling may need to overwrite these with different values
+ * to run different commands, and once error handling is complete,
+ * we will need to restore these values prior to running the actual
+ * command.
+ */
+ cmd->old_use_sg = cmd->use_sg;
+ cmd->old_cmd_len = cmd->cmd_len;
+ cmd->sc_old_data_direction = cmd->sc_data_direction;
+ cmd->old_underflow = cmd->underflow;
+ memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
+ cmd->buffer = cmd->request_buffer;
+ cmd->bufflen = cmd->request_bufflen;
+ cmd->internal_timeout = NORMAL_TIMEOUT;
+ cmd->abort_reason = 0;
+
+ return 1;
+}
+
+/*
+ * Function: scsi_setup_cmd_retry()
+ *
+ * Purpose: Restore the command state for a retry
+ *
+ * Arguments: cmd - command to be restored
+ *
+ * Returns: Nothing
+ *
+ * Notes: Immediately prior to retrying a command, we need
+ * to restore certain fields that we saved above.
+ */
+void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
+{
+ memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
+ cmd->request_buffer = cmd->buffer;
+ cmd->request_bufflen = cmd->bufflen;
+ cmd->use_sg = cmd->old_use_sg;
+ cmd->cmd_len = cmd->old_cmd_len;
+ cmd->sc_data_direction = cmd->sc_old_data_direction;
+ cmd->underflow = cmd->old_underflow;
+}
+
+void scsi_device_unbusy(struct scsi_device *sdev)
+{
+ struct Scsi_Host *shost = sdev->host;
+ unsigned long flags;
+
+ spin_lock_irqsave(shost->host_lock, flags);
+ shost->host_busy--;
+ if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
+ shost->host_failed))
+ scsi_eh_wakeup(shost);
+ spin_unlock(shost->host_lock);
+ spin_lock(&sdev->sdev_lock);
+ sdev->device_busy--;
+ spin_unlock_irqrestore(&sdev->sdev_lock, flags);
+}
+
+/*
+ * Called for single_lun devices on IO completion. Clear starget_sdev_user,
+ * and call blk_run_queue for all the scsi_devices on the target -
+ * including current_sdev first.
+ *
+ * Called with *no* scsi locks held.
+ */
+static void scsi_single_lun_run(struct scsi_device *current_sdev)
+{
+ struct Scsi_Host *shost = current_sdev->host;
+ struct scsi_device *sdev, *tmp;
+ 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_run_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);
+ blk_run_queue(sdev->request_queue);
+ spin_lock_irqsave(shost->host_lock, flags);
+
+ scsi_device_put(sdev);
+ }
+ out:
+ spin_unlock_irqrestore(shost->host_lock, flags);
+}
+
+/*
+ * Function: scsi_run_queue()
+ *
+ * Purpose: Select a proper request queue to serve next
+ *
+ * Arguments: q - last request's queue
+ *
+ * Returns: Nothing
+ *
+ * Notes: The previous command was completely finished, start
+ * a new one if possible.
+ */
+static void scsi_run_queue(struct request_queue *q)
+{
+ struct scsi_device *sdev = q->queuedata;
+ struct Scsi_Host *shost = sdev->host;
+ unsigned long flags;
+
+ if (sdev->single_lun)
+ scsi_single_lun_run(sdev);
+
+ spin_lock_irqsave(shost->host_lock, flags);
+ while (!list_empty(&shost->starved_list) &&
+ !shost->host_blocked && !shost->host_self_blocked &&
+ !((shost->can_queue > 0) &&
+ (shost->host_busy >= shost->can_queue))) {
+ /*
+ * As long as shost is accepting commands and we have
+ * starved queues, call blk_run_queue. scsi_request_fn
+ * drops the queue_lock and can add us back to the
+ * starved_list.
+ *
+ * host_lock protects the starved_list and starved_entry.
+ * scsi_request_fn must get the host_lock before checking
+ * or modifying starved_list or starved_entry.
+ */
+ sdev = list_entry(shost->starved_list.next,
+ struct scsi_device, starved_entry);
+ list_del_init(&sdev->starved_entry);
+ spin_unlock_irqrestore(shost->host_lock, flags);
+
+ blk_run_queue(sdev->request_queue);
+
+ spin_lock_irqsave(shost->host_lock, flags);
+ if (unlikely(!list_empty(&sdev->starved_entry)))
+ /*
+ * sdev lost a race, and was put back on the
+ * starved list. This is unlikely but without this
+ * in theory we could loop forever.
+ */
+ break;
+ }
+ spin_unlock_irqrestore(shost->host_lock, flags);
+
+ blk_run_queue(q);
+}
+
+/*
+ * Function: scsi_requeue_command()
+ *
+ * Purpose: Handle post-processing of completed commands.
+ *
+ * Arguments: q - queue to operate on
+ * cmd - command that may need to be requeued.
+ *
+ * Returns: Nothing
+ *
+ * Notes: After command completion, there may be blocks left
+ * over which weren't finished by the previous command
+ * this can be for a number of reasons - the main one is
+ * I/O errors in the middle of the request, in which case
+ * we need to request the blocks that come after the bad
+ * sector.
+ */
+static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
+{
+ cmd->request->flags &= ~REQ_DONTPREP;
+ blk_insert_request(q, cmd->request, 1, cmd, 1);
+
+ scsi_run_queue(q);
+}
+
+void scsi_next_command(struct scsi_cmnd *cmd)
+{
+ struct request_queue *q = cmd->device->request_queue;
+
+ scsi_put_command(cmd);
+ scsi_run_queue(q);
+}
+
+void scsi_run_host_queues(struct Scsi_Host *shost)
+{
+ struct scsi_device *sdev;
+
+ shost_for_each_device(sdev, shost)
+ scsi_run_queue(sdev->request_queue);
+}
+
+/*
+ * Function: scsi_end_request()
+ *
+ * Purpose: Post-processing of completed commands (usually invoked at end
+ * of upper level post-processing and scsi_io_completion).
+ *
+ * Arguments: cmd - command that is complete.
+ * uptodate - 1 if I/O indicates success, <= 0 for I/O error.
+ * bytes - number of bytes of completed I/O
+ * requeue - indicates whether we should requeue leftovers.
+ *
+ * Lock status: Assumed that lock is not held upon entry.
+ *
+ * Returns: cmd if requeue done or required, NULL otherwise
+ *
+ * Notes: This is called for block device requests in order to
+ * mark some number of sectors as complete.
+ *
+ * We are guaranteeing that the request queue will be goosed
+ * at some point during this call.
+ */
+static struct scsi_cmnd *scsi_end_request(struct scsi_cmnd *cmd, int uptodate,
+ int bytes, int requeue)
+{
+ request_queue_t *q = cmd->device->request_queue;
+ struct request *req = cmd->request;
+ unsigned long flags;
+
+ /*
+ * If there are blocks left over at the end, set up the command
+ * to queue the remainder of them.
+ */
+ if (end_that_request_chunk(req, uptodate, bytes)) {
+ int leftover = (req->hard_nr_sectors << 9);
+
+ if (blk_pc_request(req))
+ leftover = req->data_len;
+
+ /* kill remainder if no retrys */
+ if (!uptodate && blk_noretry_request(req))
+ end_that_request_chunk(req, 0, leftover);
+ else {
+ if (requeue)
+ /*
+ * Bleah. Leftovers again. Stick the
+ * leftovers in the front of the
+ * queue, and goose the queue again.
+ */
+ scsi_requeue_command(q, cmd);
+
+ return cmd;
+ }
+ }
+
+ add_disk_randomness(req->rq_disk);
+
+ spin_lock_irqsave(q->queue_lock, flags);
+ if (blk_rq_tagged(req))
+ blk_queue_end_tag(q, req);
+ end_that_request_last(req);
+ spin_unlock_irqrestore(q->queue_lock, flags);
+
+ /*
+ * This will goose the queue request function at the end, so we don't
+ * need to worry about launching another command.
+ */
+ scsi_next_command(cmd);
+ return NULL;
+}
+
+static struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, int gfp_mask)
+{
+ struct scsi_host_sg_pool *sgp;
+ struct scatterlist *sgl;
+
+ BUG_ON(!cmd->use_sg);
+
+ switch (cmd->use_sg) {
+ case 1 ... 8:
+ cmd->sglist_len = 0;
+ break;
+ case 9 ... 16:
+ cmd->sglist_len = 1;
+ break;
+ case 17 ... 32:
+ cmd->sglist_len = 2;
+ break;
+#if (SCSI_MAX_PHYS_SEGMENTS > 32)
+ case 33 ... 64:
+ cmd->sglist_len = 3;
+ break;
+#if (SCSI_MAX_PHYS_SEGMENTS > 64)
+ case 65 ... 128:
+ cmd->sglist_len = 4;
+ break;
+#if (SCSI_MAX_PHYS_SEGMENTS > 128)
+ case 129 ... 256:
+ cmd->sglist_len = 5;
+ break;
+#endif
+#endif
+#endif
+ default:
+ return NULL;
+ }
+
+ sgp = scsi_sg_pools + cmd->sglist_len;
+ sgl = mempool_alloc(sgp->pool, gfp_mask);
+ if (sgl)
+ memset(sgl, 0, sgp->size);
+ return sgl;
+}
+
+static void scsi_free_sgtable(struct scatterlist *sgl, int index)
+{
+ struct scsi_host_sg_pool *sgp;
+
+ BUG_ON(index > SG_MEMPOOL_NR);
+
+ sgp = scsi_sg_pools + index;
+ mempool_free(sgl, sgp->pool);
+}
+
+/*
+ * Function: scsi_release_buffers()
+ *
+ * Purpose: Completion processing for block device I/O requests.
+ *
+ * Arguments: cmd - command that we are bailing.
+ *
+ * Lock status: Assumed that no lock is held upon entry.
+ *
+ * Returns: Nothing
+ *
+ * Notes: In the event that an upper level driver rejects a
+ * command, we must release resources allocated during
+ * the __init_io() function. Primarily this would involve
+ * the scatter-gather table, and potentially any bounce
+ * buffers.
+ */
+static void scsi_release_buffers(struct scsi_cmnd *cmd)
+{
+ struct request *req = cmd->request;
+
+ /*
+ * Free up any indirection buffers we allocated for DMA purposes.
+ */
+ if (cmd->use_sg)
+ scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
+ else if (cmd->request_buffer != req->buffer)
+ kfree(cmd->request_buffer);
+
+ /*
+ * Zero these out. They now point to freed memory, and it is
+ * dangerous to hang onto the pointers.
+ */
+ cmd->buffer = NULL;
+ cmd->bufflen = 0;
+ cmd->request_buffer = NULL;
+ cmd->request_bufflen = 0;
+}
+
+/*
+ * Function: scsi_io_completion()
+ *
+ * Purpose: Completion processing for block device I/O requests.
+ *
+ * Arguments: cmd - command that is finished.
+ *
+ * Lock status: Assumed that no lock is held upon entry.
+ *
+ * Returns: Nothing
+ *
+ * Notes: This function is matched in terms of capabilities to
+ * the function that created the scatter-gather list.
+ * In other words, if there are no bounce buffers
+ * (the normal case for most drivers), we don't need
+ * the logic to deal with cleaning up afterwards.
+ *
+ * We must do one of several things here:
+ *
+ * a) Call scsi_end_request. This will finish off the
+ * specified number of sectors. If we are done, the
+ * command block will be released, and the queue
+ * function will be goosed. If we are not done, then
+ * scsi_end_request will directly goose the queue.
+ *
+ * b) We can just use scsi_requeue_command() here. This would
+ * be used if we just wanted to retry, for example.
+ */
+void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes,
+ unsigned int block_bytes)
+{
+ int result = cmd->result;
+ int this_count = cmd->bufflen;
+ request_queue_t *q = cmd->device->request_queue;
+ struct request *req = cmd->request;
+ int clear_errors = 1;
+ struct scsi_sense_hdr sshdr;
+ int sense_valid = 0;
+ int sense_deferred = 0;
+
+ if (blk_complete_barrier_rq(q, req, good_bytes >> 9))
+ return;
+
+ /*
+ * Free up any indirection buffers we allocated for DMA purposes.
+ * For the case of a READ, we need to copy the data out of the
+ * bounce buffer and into the real buffer.
+ */
+ if (cmd->use_sg)
+ scsi_free_sgtable(cmd->buffer, cmd->sglist_len);
+ else if (cmd->buffer != req->buffer) {
+ if (rq_data_dir(req) == READ) {
+ unsigned long flags;
+ char *to = bio_kmap_irq(req->bio, &flags);
+ memcpy(to, cmd->buffer, cmd->bufflen);
+ bio_kunmap_irq(to, &flags);
+ }
+ kfree(cmd->buffer);
+ }
+
+ if (result) {
+ sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
+ if (sense_valid)
+ sense_deferred = scsi_sense_is_deferred(&sshdr);
+ }
+ if (blk_pc_request(req)) { /* SG_IO ioctl from block level */
+ req->errors = result;
+ if (result) {
+ clear_errors = 0;
+ 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;
+ }
+ } else
+ req->data_len = cmd->resid;
+ }
+
+ /*
+ * Zero these out. They now point to freed memory, and it is
+ * dangerous to hang onto the pointers.
+ */
+ cmd->buffer = NULL;
+ cmd->bufflen = 0;
+ cmd->request_buffer = NULL;
+ cmd->request_bufflen = 0;
+
+ /*
+ * Next deal with any sectors which we were able to correctly
+ * handle.
+ */
+ if (good_bytes >= 0) {
+ SCSI_LOG_HLCOMPLETE(1, printk("%ld sectors total, %d bytes done.\n",
+ req->nr_sectors, good_bytes));
+ SCSI_LOG_HLCOMPLETE(1, printk("use_sg is %d\n", cmd->use_sg));
+
+ if (clear_errors)
+ req->errors = 0;
+ /*
+ * If multiple sectors are requested in one buffer, then
+ * they will have been finished off by the first command.
+ * If not, then we have a multi-buffer command.
+ *
+ * If block_bytes != 0, it means we had a medium error
+ * of some sort, and that we want to mark some number of
+ * sectors as not uptodate. Thus we want to inhibit
+ * requeueing right here - we will requeue down below
+ * when we handle the bad sectors.
+ */
+ cmd = scsi_end_request(cmd, 1, good_bytes, result == 0);
+
+ /*
+ * If the command completed without error, then either finish off the
+ * rest of the command, or start a new one.
+ */
+ if (result == 0 || cmd == NULL ) {
+ return;
+ }
+ }
+ /*
+ * Now, if we were good little boys and girls, Santa left us a request
+ * sense buffer. We can extract information from this, so we
+ * can choose a block to remap, etc.
+ */
+ if (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;
+ cmd = scsi_end_request(cmd, 0,
+ this_count, 1);
+ return;
+ } else {
+ /*
+ * Must have been a power glitch, or a
+ * bus reset. Could not have been a
+ * media change, so we just retry the
+ * request and see what happens.
+ */
+ scsi_requeue_command(q, cmd);
+ return;
+ }
+ 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 &&
+ (cmd->cmnd[0] == READ_10 ||
+ cmd->cmnd[0] == WRITE_10)) {
+ cmd->device->use_10_for_rw = 0;
+ /*
+ * This will cause a retry with a 6-byte
+ * command.
+ */
+ scsi_requeue_command(q, cmd);
+ result = 0;
+ } else {
+ cmd = scsi_end_request(cmd, 0, this_count, 1);
+ return;
+ }
+ break;
+ case NOT_READY:
+ /*
+ * If the device is in the process of becoming ready,
+ * retry.
+ */
+ if (sshdr.asc == 0x04 && sshdr.ascq == 0x01) {
+ scsi_requeue_command(q, cmd);
+ return;
+ }
+ printk(KERN_INFO "Device %s not ready.\n",
+ req->rq_disk ? req->rq_disk->disk_name : "");
+ cmd = scsi_end_request(cmd, 0, this_count, 1);
+ return;
+ case VOLUME_OVERFLOW:
+ printk(KERN_INFO "Volume overflow <%d %d %d %d> CDB: ",
+ cmd->device->host->host_no,
+ (int)cmd->device->channel,
+ (int)cmd->device->id, (int)cmd->device->lun);
+ __scsi_print_command(cmd->data_cmnd);
+ scsi_print_sense("", cmd);
+ cmd = scsi_end_request(cmd, 0, block_bytes, 1);
+ return;
+ default:
+ break;
+ }
+ } /* driver byte != 0 */
+ if (host_byte(result) == DID_RESET) {
+ /*
+ * Third party bus reset or reset for error
+ * recovery reasons. Just retry the request
+ * and see what happens.
+ */
+ scsi_requeue_command(q, cmd);
+ return;
+ }
+ if (result) {
+ printk(KERN_INFO "SCSI error : <%d %d %d %d> return code "
+ "= 0x%x\n", cmd->device->host->host_no,
+ cmd->device->channel,
+ cmd->device->id,
+ cmd->device->lun, result);
+
+ if (driver_byte(result) & DRIVER_SENSE)
+ scsi_print_sense("", cmd);
+ /*
+ * Mark a single buffer as not uptodate. Queue the remainder.
+ * We sometimes get this cruft in the event that a medium error
+ * isn't properly reported.
+ */
+ block_bytes = req->hard_cur_sectors << 9;
+ if (!block_bytes)
+ block_bytes = req->data_len;
+ cmd = scsi_end_request(cmd, 0, block_bytes, 1);
+ }
+}
+EXPORT_SYMBOL(scsi_io_completion);
+
+/*
+ * Function: scsi_init_io()
+ *
+ * Purpose: SCSI I/O initialize function.
+ *
+ * Arguments: cmd - Command descriptor we wish to initialize
+ *
+ * Returns: 0 on success
+ * BLKPREP_DEFER if the failure is retryable
+ * BLKPREP_KILL if the failure is fatal
+ */
+static int scsi_init_io(struct scsi_cmnd *cmd)
+{
+ struct request *req = cmd->request;
+ struct scatterlist *sgpnt;
+ int count;
+
+ /*
+ * if this is a rq->data based REQ_BLOCK_PC, setup for a non-sg xfer
+ */
+ if ((req->flags & REQ_BLOCK_PC) && !req->bio) {
+ cmd->request_bufflen = req->data_len;
+ cmd->request_buffer = req->data;
+ req->buffer = req->data;
+ cmd->use_sg = 0;
+ return 0;
+ }
+
+ /*
+ * we used to not use scatter-gather for single segment request,
+ * but now we do (it makes highmem I/O easier to support without
+ * kmapping pages)
+ */
+ cmd->use_sg = req->nr_phys_segments;
+
+ /*
+ * if sg table allocation fails, requeue request later.
+ */
+ sgpnt = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
+ if (unlikely(!sgpnt)) {
+ req->flags |= REQ_SPECIAL;
+ return BLKPREP_DEFER;
+ }
+
+ cmd->request_buffer = (char *) sgpnt;
+ cmd->request_bufflen = req->nr_sectors << 9;
+ if (blk_pc_request(req))
+ cmd->request_bufflen = req->data_len;
+ req->buffer = NULL;
+
+ /*
+ * Next, walk the list, and fill in the addresses and sizes of
+ * each segment.
+ */
+ count = blk_rq_map_sg(req->q, req, cmd->request_buffer);
+
+ /*
+ * mapped well, send it off
+ */
+ if (likely(count <= cmd->use_sg)) {
+ cmd->use_sg = count;
+ return 0;
+ }
+
+ printk(KERN_ERR "Incorrect number of segments after building list\n");
+ printk(KERN_ERR "counted %d, received %d\n", count, cmd->use_sg);
+ printk(KERN_ERR "req nr_sec %lu, cur_nr_sec %u\n", req->nr_sectors,
+ req->current_nr_sectors);
+
+ /* release the command and kill it */
+ scsi_release_buffers(cmd);
+ scsi_put_command(cmd);
+ return BLKPREP_KILL;
+}
+
+static int scsi_prepare_flush_fn(request_queue_t *q, struct request *rq)
+{
+ struct scsi_device *sdev = q->queuedata;
+ struct scsi_driver *drv;
+
+ if (sdev->sdev_state == SDEV_RUNNING) {
+ drv = *(struct scsi_driver **) rq->rq_disk->private_data;
+
+ if (drv->prepare_flush)
+ return drv->prepare_flush(q, rq);
+ }
+
+ return 0;
+}
+
+static void scsi_end_flush_fn(request_queue_t *q, struct request *rq)
+{
+ struct scsi_device *sdev = q->queuedata;
+ struct request *flush_rq = rq->end_io_data;
+ struct scsi_driver *drv;
+
+ if (flush_rq->errors) {
+ printk("scsi: barrier error, disabling flush support\n");
+ blk_queue_ordered(q, QUEUE_ORDERED_NONE);
+ }
+
+ if (sdev->sdev_state == SDEV_RUNNING) {
+ drv = *(struct scsi_driver **) rq->rq_disk->private_data;
+ drv->end_flush(q, rq);
+ }
+}
+
+static int scsi_issue_flush_fn(request_queue_t *q, struct gendisk *disk,
+ sector_t *error_sector)
+{
+ struct scsi_device *sdev = q->queuedata;
+ struct scsi_driver *drv;
+
+ if (sdev->sdev_state != SDEV_RUNNING)
+ return -ENXIO;
+
+ drv = *(struct scsi_driver **) disk->private_data;
+ if (drv->issue_flush)
+ return drv->issue_flush(&sdev->sdev_gendev, error_sector);
+
+ return -EOPNOTSUPP;
+}
+
+static int scsi_prep_fn(struct request_queue *q, struct request *req)
+{
+ struct scsi_device *sdev = q->queuedata;
+ struct scsi_cmnd *cmd;
+ int specials_only = 0;
+
+ /*
+ * Just check to see if the device is online. If it isn't, we
+ * refuse to process any commands. The device must be brought
+ * online before trying any recovery commands
+ */
+ if (unlikely(!scsi_device_online(sdev))) {
+ printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
+ sdev->host->host_no, sdev->id, sdev->lun);
+ return BLKPREP_KILL;
+ }
+ if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
+ /* OK, we're not in a running state don't prep
+ * user commands */
+ if (sdev->sdev_state == SDEV_DEL) {
+ /* Device is fully deleted, no commands
+ * at all allowed down */
+ printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to dead device\n",
+ sdev->host->host_no, sdev->id, sdev->lun);
+ return BLKPREP_KILL;
+ }
+ /* OK, we only allow special commands (i.e. not
+ * user initiated ones */
+ specials_only = sdev->sdev_state;
+ }
+
+ /*
+ * Find the actual device driver associated with this command.
+ * The SPECIAL requests are things like character device or
+ * ioctls, which did not originate from ll_rw_blk. Note that
+ * the special field is also used to indicate the cmd for
+ * the remainder of a partially fulfilled request that can
+ * come up when there is a medium error. We have to treat
+ * these two cases differently. We differentiate by looking
+ * at request->cmd, as this tells us the real story.
+ */
+ if (req->flags & REQ_SPECIAL) {
+ struct scsi_request *sreq = req->special;
+
+ if (sreq->sr_magic == SCSI_REQ_MAGIC) {
+ cmd = scsi_get_command(sreq->sr_device, GFP_ATOMIC);
+ if (unlikely(!cmd))
+ goto defer;
+ scsi_init_cmd_from_req(cmd, sreq);
+ } else
+ cmd = req->special;
+ } else if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
+
+ if(unlikely(specials_only)) {
+ if(specials_only == SDEV_QUIESCE ||
+ specials_only == SDEV_BLOCK)
+ return BLKPREP_DEFER;
+
+ printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to device being removed\n",
+ sdev->host->host_no, sdev->id, sdev->lun);
+ return BLKPREP_KILL;
+ }
+
+
+ /*
+ * Now try and find a command block that we can use.
+ */
+ if (!req->special) {
+ cmd = scsi_get_command(sdev, GFP_ATOMIC);
+ if (unlikely(!cmd))
+ goto defer;
+ } else
+ cmd = req->special;
+
+ /* pull a tag out of the request if we have one */
+ cmd->tag = req->tag;
+ } else {
+ blk_dump_rq_flags(req, "SCSI bad req");
+ return BLKPREP_KILL;
+ }
+
+ /* note the overloading of req->special. When the tag
+ * is active it always means cmd. If the tag goes
+ * back for re-queueing, it may be reset */
+ req->special = cmd;
+ cmd->request = req;
+
+ /*
+ * FIXME: drop the lock here because the functions below
+ * expect to be called without the queue lock held. Also,
+ * previously, we dequeued the request before dropping the
+ * lock. We hope REQ_STARTED prevents anything untoward from
+ * happening now.
+ */
+ if (req->flags & (REQ_CMD | REQ_BLOCK_PC)) {
+ struct scsi_driver *drv;
+ int ret;
+
+ /*
+ * This will do a couple of things:
+ * 1) Fill in the actual SCSI command.
+ * 2) Fill in any other upper-level specific fields
+ * (timeout).
+ *
+ * If this returns 0, it means that the request failed
+ * (reading past end of disk, reading offline device,
+ * etc). This won't actually talk to the device, but
+ * some kinds of consistency checking may cause the
+ * request to be rejected immediately.
+ */
+
+ /*
+ * This sets up the scatter-gather table (allocating if
+ * required).
+ */
+ ret = scsi_init_io(cmd);
+ if (ret) /* BLKPREP_KILL return also releases the command */
+ return ret;
+
+ /*
+ * Initialize the actual SCSI command for this request.
+ */
+ drv = *(struct scsi_driver **)req->rq_disk->private_data;
+ if (unlikely(!drv->init_command(cmd))) {
+ scsi_release_buffers(cmd);
+ scsi_put_command(cmd);
+ return BLKPREP_KILL;
+ }
+ }
+
+ /*
+ * The request is now prepped, no need to come back here
+ */
+ req->flags |= REQ_DONTPREP;
+ return BLKPREP_OK;
+
+ defer:
+ /* If we defer, the elv_next_request() returns NULL, but the
+ * queue must be restarted, so we plug here if no returning
+ * command will automatically do that. */
+ if (sdev->device_busy == 0)
+ blk_plug_device(q);
+ return BLKPREP_DEFER;
+}
+
+/*
+ * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
+ * return 0.
+ *
+ * Called with the queue_lock held.
+ */
+static inline int scsi_dev_queue_ready(struct request_queue *q,
+ struct scsi_device *sdev)
+{
+ if (sdev->device_busy >= sdev->queue_depth)
+ return 0;
+ if (sdev->device_busy == 0 && sdev->device_blocked) {
+ /*
+ * unblock after device_blocked iterates to zero
+ */
+ if (--sdev->device_blocked == 0) {
+ SCSI_LOG_MLQUEUE(3,
+ printk("scsi%d (%d:%d) unblocking device at"
+ " zero depth\n", sdev->host->host_no,
+ sdev->id, sdev->lun));
+ } else {
+ blk_plug_device(q);
+ return 0;
+ }
+ }
+ if (sdev->device_blocked)
+ return 0;
+
+ return 1;
+}
+
+/*
+ * scsi_host_queue_ready: if we can send requests to shost, return 1 else
+ * return 0. We must end up running the queue again whenever 0 is
+ * returned, else IO can hang.
+ *
+ * Called with host_lock held.
+ */
+static inline int scsi_host_queue_ready(struct request_queue *q,
+ struct Scsi_Host *shost,
+ struct scsi_device *sdev)
+{
+ if (test_bit(SHOST_RECOVERY, &shost->shost_state))
+ return 0;
+ if (shost->host_busy == 0 && shost->host_blocked) {
+ /*
+ * unblock after host_blocked iterates to zero
+ */
+ if (--shost->host_blocked == 0) {
+ SCSI_LOG_MLQUEUE(3,
+ printk("scsi%d unblocking host at zero depth\n",
+ shost->host_no));
+ } else {
+ blk_plug_device(q);
+ return 0;
+ }
+ }
+ if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
+ shost->host_blocked || shost->host_self_blocked) {
+ if (list_empty(&sdev->starved_entry))
+ list_add_tail(&sdev->starved_entry, &shost->starved_list);
+ return 0;
+ }
+
+ /* We're OK to process the command, so we can't be starved */
+ if (!list_empty(&sdev->starved_entry))
+ list_del_init(&sdev->starved_entry);
+
+ return 1;
+}
+
+/*
+ * Kill requests for a dead device
+ */
+static void scsi_kill_requests(request_queue_t *q)
+{
+ struct request *req;
+
+ while ((req = elv_next_request(q)) != NULL) {
+ blkdev_dequeue_request(req);
+ req->flags |= REQ_QUIET;
+ while (end_that_request_first(req, 0, req->nr_sectors))
+ ;
+ end_that_request_last(req);
+ }
+}
+
+/*
+ * Function: scsi_request_fn()
+ *
+ * Purpose: Main strategy routine for SCSI.
+ *
+ * Arguments: q - Pointer to actual queue.
+ *
+ * Returns: Nothing
+ *
+ * Lock status: IO request lock assumed to be held when called.
+ */
+static void scsi_request_fn(struct request_queue *q)
+{
+ struct scsi_device *sdev = q->queuedata;
+ struct Scsi_Host *shost;
+ struct scsi_cmnd *cmd;
+ struct request *req;
+
+ if (!sdev) {
+ printk("scsi: killing requests for dead queue\n");
+ scsi_kill_requests(q);
+ return;
+ }
+
+ if(!get_device(&sdev->sdev_gendev))
+ /* We must be tearing the block queue down already */
+ return;
+
+ /*
+ * To start with, we keep looping until the queue is empty, or until
+ * the host is no longer able to accept any more requests.
+ */
+ shost = sdev->host;
+ while (!blk_queue_plugged(q)) {
+ int rtn;
+ /*
+ * get next queueable request. We do this early to make sure
+ * that the request is fully prepared even if we cannot
+ * accept it.
+ */
+ req = elv_next_request(q);
+ if (!req || !scsi_dev_queue_ready(q, sdev))
+ break;
+
+ if (unlikely(!scsi_device_online(sdev))) {
+ printk(KERN_ERR "scsi%d (%d:%d): rejecting I/O to offline device\n",
+ sdev->host->host_no, sdev->id, sdev->lun);
+ blkdev_dequeue_request(req);
+ req->flags |= REQ_QUIET;
+ while (end_that_request_first(req, 0, req->nr_sectors))
+ ;
+ end_that_request_last(req);
+ continue;
+ }
+
+
+ /*
+ * Remove the request from the request list.
+ */
+ if (!(blk_queue_tagged(q) && !blk_queue_start_tag(q, req)))
+ blkdev_dequeue_request(req);
+ sdev->device_busy++;
+
+ spin_unlock(q->queue_lock);
+ spin_lock(shost->host_lock);
+
+ if (!scsi_host_queue_ready(q, shost, sdev))
+ goto not_ready;
+ if (sdev->single_lun) {
+ if (scsi_target(sdev)->starget_sdev_user &&
+ scsi_target(sdev)->starget_sdev_user != sdev)
+ goto not_ready;
+ scsi_target(sdev)->starget_sdev_user = sdev;
+ }
+ shost->host_busy++;
+
+ /*
+ * XXX(hch): This is rather suboptimal, scsi_dispatch_cmd will
+ * take the lock again.
+ */
+ spin_unlock_irq(shost->host_lock);
+
+ cmd = req->special;
+ if (unlikely(cmd == NULL)) {
+ printk(KERN_CRIT "impossible request in %s.\n"
+ "please mail a stack trace to "
+ "linux-scsi@vger.kernel.org",
+ __FUNCTION__);
+ BUG();
+ }
+
+ /*
+ * Finally, initialize any error handling parameters, and set up
+ * the timers for timeouts.
+ */
+ scsi_init_cmd_errh(cmd);
+
+ /*
+ * Dispatch the command to the low-level driver.
+ */
+ rtn = scsi_dispatch_cmd(cmd);
+ spin_lock_irq(q->queue_lock);
+ if(rtn) {
+ /* we're refusing the command; because of
+ * the way locks get dropped, we need to
+ * check here if plugging is required */
+ if(sdev->device_busy == 0)
+ blk_plug_device(q);
+
+ break;
+ }
+ }
+
+ goto out;
+
+ not_ready:
+ spin_unlock_irq(shost->host_lock);
+
+ /*
+ * lock q, handle tag, requeue req, and decrement device_busy. We
+ * must return with queue_lock held.
+ *
+ * Decrementing device_busy without checking it is OK, as all such
+ * cases (host limits or settings) should run the queue at some
+ * later time.
+ */
+ spin_lock_irq(q->queue_lock);
+ blk_requeue_request(q, req);
+ sdev->device_busy--;
+ if(sdev->device_busy == 0)
+ blk_plug_device(q);
+ out:
+ /* must be careful here...if we trigger the ->remove() function
+ * we cannot be holding the q lock */
+ spin_unlock_irq(q->queue_lock);
+ put_device(&sdev->sdev_gendev);
+ spin_lock_irq(q->queue_lock);
+}
+
+u64 scsi_calculate_bounce_limit(struct Scsi_Host *shost)
+{
+ struct device *host_dev;
+ 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 = *host_dev->dma_mask;
+
+ return bounce_limit;
+}
+EXPORT_SYMBOL(scsi_calculate_bounce_limit);
+
+struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
+{
+ struct Scsi_Host *shost = sdev->host;
+ struct request_queue *q;
+
+ q = blk_init_queue(scsi_request_fn, &sdev->sdev_lock);
+ if (!q)
+ return NULL;
+
+ blk_queue_prep_rq(q, scsi_prep_fn);
+
+ blk_queue_max_hw_segments(q, shost->sg_tablesize);
+ blk_queue_max_phys_segments(q, SCSI_MAX_PHYS_SEGMENTS);
+ blk_queue_max_sectors(q, shost->max_sectors);
+ blk_queue_bounce_limit(q, scsi_calculate_bounce_limit(shost));
+ blk_queue_segment_boundary(q, shost->dma_boundary);
+ blk_queue_issue_flush_fn(q, scsi_issue_flush_fn);
+
+ /*
+ * ordered tags are superior to flush ordering
+ */
+ if (shost->ordered_tag)
+ blk_queue_ordered(q, QUEUE_ORDERED_TAG);
+ else if (shost->ordered_flush) {
+ blk_queue_ordered(q, QUEUE_ORDERED_FLUSH);
+ q->prepare_flush_fn = scsi_prepare_flush_fn;
+ q->end_flush_fn = scsi_end_flush_fn;
+ }
+
+ if (!shost->use_clustering)
+ clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
+ return q;
+}
+
+void scsi_free_queue(struct request_queue *q)
+{
+ blk_cleanup_queue(q);
+}
+
+/*
+ * Function: scsi_block_requests()
+ *
+ * Purpose: Utility function used by low-level drivers to prevent further
+ * commands from being queued to the device.
+ *
+ * Arguments: shost - Host in question
+ *
+ * Returns: Nothing
+ *
+ * Lock status: No locks are assumed held.
+ *
+ * Notes: There is no timer nor any other means by which the requests
+ * get unblocked other than the low-level driver calling
+ * scsi_unblock_requests().
+ */
+void scsi_block_requests(struct Scsi_Host *shost)
+{
+ shost->host_self_blocked = 1;
+}
+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;
+
+ for (i = 0; i < SG_MEMPOOL_NR; i++) {
+ struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
+ int size = sgp->size * sizeof(struct scatterlist);
+
+ sgp->slab = kmem_cache_create(sgp->name, size, 0,
+ SLAB_HWCACHE_ALIGN, NULL, NULL);
+ if (!sgp->slab) {
+ printk(KERN_ERR "SCSI: can't init sg slab %s\n",
+ sgp->name);
+ }
+
+ sgp->pool = mempool_create(SG_MEMPOOL_SIZE,
+ mempool_alloc_slab, mempool_free_slab,
+ sgp->slab);
+ if (!sgp->pool) {
+ printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
+ sgp->name);
+ }
+ }
+
+ return 0;
+}
+
+void scsi_exit_queue(void)
+{
+ int i;
+
+ for (i = 0; i < SG_MEMPOOL_NR; i++) {
+ struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
+ mempool_destroy(sgp->pool);
+ kmem_cache_destroy(sgp->slab);
+ }
+}
+/**
+ * __scsi_mode_sense - issue a mode sense, falling back from 10 to
+ * six bytes if necessary.
+ * @sreq: SCSI request to fill in with the MODE_SENSE
+ * @dbd: set if mode sense will allow block descriptors to be returned
+ * @modepage: mode page being requested
+ * @buffer: request buffer (may not be smaller than eight bytes)
+ * @len: length of request buffer.
+ * @timeout: command timeout
+ * @retries: number of retries before failing
+ * @data: returns a structure abstracting the mode header data
+ *
+ * Returns zero if unsuccessful, or the header offset (either 4
+ * or 8 depending on whether a six or ten byte command was
+ * issued) if successful.
+ **/
+int
+__scsi_mode_sense(struct scsi_request *sreq, int dbd, int modepage,
+ unsigned char *buffer, int len, int timeout, int retries,
+ struct scsi_mode_data *data) {
+ unsigned char cmd[12];
+ int use_10_for_ms;
+ int header_length;
+
+ memset(data, 0, sizeof(*data));
+ memset(&cmd[0], 0, 12);
+ cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
+ cmd[2] = modepage;
+
+ retry:
+ use_10_for_ms = sreq->sr_device->use_10_for_ms;
+
+ if (use_10_for_ms) {
+ if (len < 8)
+ len = 8;
+
+ cmd[0] = MODE_SENSE_10;
+ cmd[8] = len;
+ header_length = 8;
+ } else {
+ if (len < 4)
+ len = 4;
+
+ cmd[0] = MODE_SENSE;
+ cmd[4] = len;
+ header_length = 4;
+ }
+
+ sreq->sr_cmd_len = 0;
+ memset(sreq->sr_sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
+ sreq->sr_data_direction = DMA_FROM_DEVICE;
+
+ memset(buffer, 0, len);
+
+ scsi_wait_req(sreq, cmd, buffer, len, timeout, retries);
+
+ /* This code looks awful: what it's doing is making sure an
+ * ILLEGAL REQUEST sense return identifies the actual command
+ * byte as the problem. MODE_SENSE commands can return
+ * ILLEGAL REQUEST if the code page isn't supported */
+
+ if (use_10_for_ms && !scsi_status_is_good(sreq->sr_result) &&
+ (driver_byte(sreq->sr_result) & DRIVER_SENSE)) {
+ struct scsi_sense_hdr sshdr;
+
+ if (scsi_request_normalize_sense(sreq, &sshdr)) {
+ if ((sshdr.sense_key == ILLEGAL_REQUEST) &&
+ (sshdr.asc == 0x20) && (sshdr.ascq == 0)) {
+ /*
+ * Invalid command operation code
+ */
+ sreq->sr_device->use_10_for_ms = 0;
+ goto retry;
+ }
+ }
+ }
+
+ if(scsi_status_is_good(sreq->sr_result)) {
+ data->header_length = header_length;
+ if(use_10_for_ms) {
+ data->length = buffer[0]*256 + buffer[1] + 2;
+ data->medium_type = buffer[2];
+ data->device_specific = buffer[3];
+ data->longlba = buffer[4] & 0x01;
+ data->block_descriptor_length = buffer[6]*256
+ + buffer[7];
+ } else {
+ data->length = buffer[0] + 1;
+ data->medium_type = buffer[1];
+ data->device_specific = buffer[2];
+ data->block_descriptor_length = buffer[3];
+ }
+ }
+
+ return sreq->sr_result;
+}
+EXPORT_SYMBOL(__scsi_mode_sense);
+
+/**
+ * scsi_mode_sense - issue a mode sense, falling back from 10 to
+ * six bytes if necessary.
+ * @sdev: scsi device to send command to.
+ * @dbd: set if mode sense will disable block descriptors in the return
+ * @modepage: mode page being requested
+ * @buffer: request buffer (may not be smaller than eight bytes)
+ * @len: length of request buffer.
+ * @timeout: command timeout
+ * @retries: number of retries before failing
+ *
+ * Returns zero if unsuccessful, or the header offset (either 4
+ * or 8 depending on whether a six or ten byte command was
+ * issued) if successful.
+ **/
+int
+scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
+ unsigned char *buffer, int len, int timeout, int retries,
+ struct scsi_mode_data *data)
+{
+ struct scsi_request *sreq = scsi_allocate_request(sdev, GFP_KERNEL);
+ int ret;
+
+ if (!sreq)
+ return -1;
+
+ ret = __scsi_mode_sense(sreq, dbd, modepage, buffer, len,
+ timeout, retries, data);
+
+ scsi_release_request(sreq);
+
+ return ret;
+}
+EXPORT_SYMBOL(scsi_mode_sense);
+
+int
+scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
+{
+ struct scsi_request *sreq;
+ char cmd[] = {
+ TEST_UNIT_READY, 0, 0, 0, 0, 0,
+ };
+ int result;
+
+ sreq = scsi_allocate_request(sdev, GFP_KERNEL);
+ if (!sreq)
+ return -ENOMEM;
+
+ sreq->sr_data_direction = DMA_NONE;
+ scsi_wait_req(sreq, cmd, NULL, 0, timeout, retries);
+
+ if ((driver_byte(sreq->sr_result) & DRIVER_SENSE) && sdev->removable) {
+ struct scsi_sense_hdr sshdr;
+
+ if ((scsi_request_normalize_sense(sreq, &sshdr)) &&
+ ((sshdr.sense_key == UNIT_ATTENTION) ||
+ (sshdr.sense_key == NOT_READY))) {
+ sdev->changed = 1;
+ sreq->sr_result = 0;
+ }
+ }
+ result = sreq->sr_result;
+ scsi_release_request(sreq);
+ 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:
+ /* There are no legal states that come back to
+ * created. This is the manually initialised start
+ * state */
+ goto illegal;
+
+ case SDEV_RUNNING:
+ switch (oldstate) {
+ case SDEV_CREATED:
+ case SDEV_OFFLINE:
+ case SDEV_QUIESCE:
+ case SDEV_BLOCK:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
+
+ case SDEV_QUIESCE:
+ switch (oldstate) {
+ case SDEV_RUNNING:
+ case SDEV_OFFLINE:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
+
+ case SDEV_OFFLINE:
+ switch (oldstate) {
+ case SDEV_CREATED:
+ case SDEV_RUNNING:
+ case SDEV_QUIESCE:
+ case SDEV_BLOCK:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
+
+ case SDEV_BLOCK:
+ switch (oldstate) {
+ case SDEV_CREATED:
+ case SDEV_RUNNING:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
+
+ case SDEV_CANCEL:
+ switch (oldstate) {
+ case SDEV_CREATED:
+ case SDEV_RUNNING:
+ case SDEV_OFFLINE:
+ case SDEV_BLOCK:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
+
+ case SDEV_DEL:
+ switch (oldstate) {
+ case SDEV_CANCEL:
+ break;
+ default:
+ goto illegal;
+ }
+ break;
+
+ }
+ sdev->sdev_state = state;
+ return 0;
+
+ illegal:
+ SCSI_LOG_ERROR_RECOVERY(1,
+ dev_printk(KERN_ERR, &sdev->sdev_gendev,
+ "Illegal state transition %s->%s\n",
+ scsi_device_state_name(oldstate),
+ scsi_device_state_name(state))
+ );
+ return -EINVAL;
+}
+EXPORT_SYMBOL(scsi_device_set_state);
+
+/**
+ * scsi_device_quiesce - Block user issued commands.
+ * @sdev: scsi device to quiesce.
+ *
+ * This works by trying to transition to the SDEV_QUIESCE state
+ * (which must be a legal transition). When the device is in this
+ * state, only special requests will be accepted, all others will
+ * be deferred. Since special requests may also be requeued requests,
+ * a successful return doesn't guarantee the device will be
+ * totally quiescent.
+ *
+ * Must be called with user context, may sleep.
+ *
+ * Returns zero if unsuccessful or an error if not.
+ **/
+int
+scsi_device_quiesce(struct scsi_device *sdev)
+{
+ int err = scsi_device_set_state(sdev, SDEV_QUIESCE);
+ if (err)
+ return err;
+
+ scsi_run_queue(sdev->request_queue);
+ while (sdev->device_busy) {
+ 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)
+{
+ if(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.
+ * This routine assumes the host_lock is held on entry.
+ **/
+int
+scsi_internal_device_block(struct scsi_device *sdev)
+{
+ request_queue_t *q = sdev->request_queue;
+ unsigned long flags;
+ int err = 0;
+
+ err = scsi_device_set_state(sdev, SDEV_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.
+ */
+ 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
+ *
+ * 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
+ * (which must be a legal transition) allowing the midlayer to
+ * goose the queue for this device. This routine assumes the
+ * host_lock is held upon entry.
+ **/
+int
+scsi_internal_device_unblock(struct scsi_device *sdev)
+{
+ request_queue_t *q = sdev->request_queue;
+ int err;
+ unsigned long flags;
+
+ /*
+ * Try to transition the scsi device to SDEV_RUNNING
+ * and goose the device queue if successful.
+ */
+ err = scsi_device_set_state(sdev, SDEV_RUNNING);
+ if (err)
+ return err;
+
+ 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);
+}
+
+static int
+target_unblock(struct device *dev, void *data)
+{
+ if (scsi_is_target_device(dev))
+ starget_for_each_device(to_scsi_target(dev), NULL,
+ device_unblock);
+ return 0;
+}
+
+void
+scsi_target_unblock(struct device *dev)
+{
+ if (scsi_is_target_device(dev))
+ starget_for_each_device(to_scsi_target(dev), NULL,
+ device_unblock);
+ else
+ device_for_each_child(dev, NULL, target_unblock);
+}
+EXPORT_SYMBOL_GPL(scsi_target_unblock);
