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![goggin, edward](/assets/img/avatar_default.png)
The problem is that scsi_run_queue is called from scsi_next_command() after doing a scsi_put_command. If the command was the only thing holding the reference on the scsi_device then the resulting device put will tear down the block queue. Fix this by taking a reference to the device and holding it around scsi_run_queue() Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2066 lines
53 KiB
C
2066 lines
53 KiB
C
/*
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* scsi_lib.c Copyright (C) 1999 Eric Youngdale
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*
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* SCSI queueing library.
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* Initial versions: Eric Youngdale (eric@andante.org).
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* Based upon conversations with large numbers
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* of people at Linux Expo.
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*/
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include <linux/completion.h>
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#include <linux/kernel.h>
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#include <linux/mempool.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/pci.h>
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#include <linux/delay.h>
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#include <scsi/scsi.h>
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#include <scsi/scsi_dbg.h>
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#include <scsi/scsi_device.h>
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#include <scsi/scsi_driver.h>
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#include <scsi/scsi_eh.h>
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#include <scsi/scsi_host.h>
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#include <scsi/scsi_request.h>
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#include "scsi_priv.h"
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#include "scsi_logging.h"
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#define SG_MEMPOOL_NR (sizeof(scsi_sg_pools)/sizeof(struct scsi_host_sg_pool))
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#define SG_MEMPOOL_SIZE 32
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struct scsi_host_sg_pool {
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size_t size;
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char *name;
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kmem_cache_t *slab;
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mempool_t *pool;
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};
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#if (SCSI_MAX_PHYS_SEGMENTS < 32)
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#error SCSI_MAX_PHYS_SEGMENTS is too small
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#endif
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#define SP(x) { x, "sgpool-" #x }
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static struct scsi_host_sg_pool scsi_sg_pools[] = {
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SP(8),
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SP(16),
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SP(32),
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#if (SCSI_MAX_PHYS_SEGMENTS > 32)
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SP(64),
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#if (SCSI_MAX_PHYS_SEGMENTS > 64)
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SP(128),
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#if (SCSI_MAX_PHYS_SEGMENTS > 128)
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SP(256),
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#if (SCSI_MAX_PHYS_SEGMENTS > 256)
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#error SCSI_MAX_PHYS_SEGMENTS is too large
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#endif
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#endif
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#endif
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#endif
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};
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#undef SP
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/*
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* Function: scsi_insert_special_req()
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*
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* Purpose: Insert pre-formed request into request queue.
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*
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* Arguments: sreq - request that is ready to be queued.
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* at_head - boolean. True if we should insert at head
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* of queue, false if we should insert at tail.
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*
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* Lock status: Assumed that lock is not held upon entry.
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*
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* Returns: Nothing
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*
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* Notes: This function is called from character device and from
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* ioctl types of functions where the caller knows exactly
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* what SCSI command needs to be issued. The idea is that
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* we merely inject the command into the queue (at the head
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* for now), and then call the queue request function to actually
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* process it.
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*/
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int scsi_insert_special_req(struct scsi_request *sreq, int at_head)
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{
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/*
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* Because users of this function are apt to reuse requests with no
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* modification, we have to sanitise the request flags here
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*/
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sreq->sr_request->flags &= ~REQ_DONTPREP;
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blk_insert_request(sreq->sr_device->request_queue, sreq->sr_request,
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at_head, sreq);
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return 0;
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}
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static void scsi_run_queue(struct request_queue *q);
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/*
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* Function: scsi_unprep_request()
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*
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* Purpose: Remove all preparation done for a request, including its
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* associated scsi_cmnd, so that it can be requeued.
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*
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* Arguments: req - request to unprepare
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*
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* Lock status: Assumed that no locks are held upon entry.
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*
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* Returns: Nothing.
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*/
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static void scsi_unprep_request(struct request *req)
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{
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struct scsi_cmnd *cmd = req->special;
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req->flags &= ~REQ_DONTPREP;
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req->special = (req->flags & REQ_SPECIAL) ? cmd->sc_request : NULL;
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scsi_put_command(cmd);
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}
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/*
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* Function: scsi_queue_insert()
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*
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* Purpose: Insert a command in the midlevel queue.
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*
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* Arguments: cmd - command that we are adding to queue.
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* reason - why we are inserting command to queue.
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*
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* Lock status: Assumed that lock is not held upon entry.
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*
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* Returns: Nothing.
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*
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* Notes: We do this for one of two cases. Either the host is busy
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* and it cannot accept any more commands for the time being,
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* or the device returned QUEUE_FULL and can accept no more
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* commands.
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* Notes: This could be called either from an interrupt context or a
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* normal process context.
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*/
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int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
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{
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struct Scsi_Host *host = cmd->device->host;
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struct scsi_device *device = cmd->device;
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struct request_queue *q = device->request_queue;
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unsigned long flags;
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SCSI_LOG_MLQUEUE(1,
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printk("Inserting command %p into mlqueue\n", cmd));
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/*
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* Set the appropriate busy bit for the device/host.
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*
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* If the host/device isn't busy, assume that something actually
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* completed, and that we should be able to queue a command now.
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*
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* Note that the prior mid-layer assumption that any host could
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* always queue at least one command is now broken. The mid-layer
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* will implement a user specifiable stall (see
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* scsi_host.max_host_blocked and scsi_device.max_device_blocked)
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* if a command is requeued with no other commands outstanding
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* either for the device or for the host.
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*/
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if (reason == SCSI_MLQUEUE_HOST_BUSY)
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host->host_blocked = host->max_host_blocked;
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else if (reason == SCSI_MLQUEUE_DEVICE_BUSY)
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device->device_blocked = device->max_device_blocked;
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/*
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* Decrement the counters, since these commands are no longer
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* active on the host/device.
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*/
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scsi_device_unbusy(device);
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/*
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* Requeue this command. It will go before all other commands
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* that are already in the queue.
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*
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* NOTE: there is magic here about the way the queue is plugged if
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* we have no outstanding commands.
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*
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* Although we *don't* plug the queue, we call the request
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* function. The SCSI request function detects the blocked condition
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* and plugs the queue appropriately.
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*/
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spin_lock_irqsave(q->queue_lock, flags);
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blk_requeue_request(q, cmd->request);
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spin_unlock_irqrestore(q->queue_lock, flags);
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scsi_run_queue(q);
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return 0;
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}
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/*
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* Function: scsi_do_req
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*
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* Purpose: Queue a SCSI request
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*
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* Arguments: sreq - command descriptor.
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* cmnd - actual SCSI command to be performed.
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* buffer - data buffer.
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* bufflen - size of data buffer.
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* done - completion function to be run.
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* timeout - how long to let it run before timeout.
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* retries - number of retries we allow.
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*
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* Lock status: No locks held upon entry.
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*
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* Returns: Nothing.
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*
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* Notes: This function is only used for queueing requests for things
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* like ioctls and character device requests - this is because
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* we essentially just inject a request into the queue for the
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* device.
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*
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* In order to support the scsi_device_quiesce function, we
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* now inject requests on the *head* of the device queue
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* rather than the tail.
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*/
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void scsi_do_req(struct scsi_request *sreq, const void *cmnd,
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void *buffer, unsigned bufflen,
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void (*done)(struct scsi_cmnd *),
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int timeout, int retries)
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{
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/*
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* If the upper level driver is reusing these things, then
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* we should release the low-level block now. Another one will
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* be allocated later when this request is getting queued.
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*/
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__scsi_release_request(sreq);
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/*
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* Our own function scsi_done (which marks the host as not busy,
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* disables the timeout counter, etc) will be called by us or by the
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* scsi_hosts[host].queuecommand() function needs to also call
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* the completion function for the high level driver.
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*/
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memcpy(sreq->sr_cmnd, cmnd, sizeof(sreq->sr_cmnd));
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sreq->sr_bufflen = bufflen;
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sreq->sr_buffer = buffer;
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sreq->sr_allowed = retries;
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sreq->sr_done = done;
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sreq->sr_timeout_per_command = timeout;
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if (sreq->sr_cmd_len == 0)
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sreq->sr_cmd_len = COMMAND_SIZE(sreq->sr_cmnd[0]);
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/*
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* head injection *required* here otherwise quiesce won't work
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*/
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scsi_insert_special_req(sreq, 1);
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}
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EXPORT_SYMBOL(scsi_do_req);
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/**
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* scsi_execute - insert request and wait for the result
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* @sdev: scsi device
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* @cmd: scsi command
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* @data_direction: data direction
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* @buffer: data buffer
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* @bufflen: len of buffer
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* @sense: optional sense buffer
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* @timeout: request timeout in seconds
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* @retries: number of times to retry request
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* @flags: or into request flags;
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*
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* returns the req->errors value which is the the scsi_cmnd result
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* field.
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**/
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int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
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int data_direction, void *buffer, unsigned bufflen,
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unsigned char *sense, int timeout, int retries, int flags)
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{
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struct request *req;
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int write = (data_direction == DMA_TO_DEVICE);
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int ret = DRIVER_ERROR << 24;
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req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
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if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
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buffer, bufflen, __GFP_WAIT))
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goto out;
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req->cmd_len = COMMAND_SIZE(cmd[0]);
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memcpy(req->cmd, cmd, req->cmd_len);
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req->sense = sense;
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req->sense_len = 0;
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req->timeout = timeout;
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req->flags |= flags | REQ_BLOCK_PC | REQ_SPECIAL | REQ_QUIET;
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/*
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* head injection *required* here otherwise quiesce won't work
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*/
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blk_execute_rq(req->q, NULL, req, 1);
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ret = req->errors;
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out:
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blk_put_request(req);
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return ret;
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}
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EXPORT_SYMBOL(scsi_execute);
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int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
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int data_direction, void *buffer, unsigned bufflen,
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struct scsi_sense_hdr *sshdr, int timeout, int retries)
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{
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char *sense = NULL;
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int result;
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if (sshdr) {
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sense = kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
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if (!sense)
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return DRIVER_ERROR << 24;
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memset(sense, 0, SCSI_SENSE_BUFFERSIZE);
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}
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result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
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sense, timeout, retries, 0);
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if (sshdr)
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scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
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kfree(sense);
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return result;
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}
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EXPORT_SYMBOL(scsi_execute_req);
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/*
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* Function: scsi_init_cmd_errh()
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*
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* Purpose: Initialize cmd fields related to error handling.
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*
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* Arguments: cmd - command that is ready to be queued.
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*
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* Returns: Nothing
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*
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* Notes: This function has the job of initializing a number of
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* fields related to error handling. Typically this will
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* be called once for each command, as required.
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*/
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static int scsi_init_cmd_errh(struct scsi_cmnd *cmd)
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{
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cmd->serial_number = 0;
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memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
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if (cmd->cmd_len == 0)
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cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
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/*
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* We need saved copies of a number of fields - this is because
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* error handling may need to overwrite these with different values
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* to run different commands, and once error handling is complete,
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* we will need to restore these values prior to running the actual
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* command.
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*/
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cmd->old_use_sg = cmd->use_sg;
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cmd->old_cmd_len = cmd->cmd_len;
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cmd->sc_old_data_direction = cmd->sc_data_direction;
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cmd->old_underflow = cmd->underflow;
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memcpy(cmd->data_cmnd, cmd->cmnd, sizeof(cmd->cmnd));
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cmd->buffer = cmd->request_buffer;
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cmd->bufflen = cmd->request_bufflen;
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return 1;
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}
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/*
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* Function: scsi_setup_cmd_retry()
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*
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* Purpose: Restore the command state for a retry
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*
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* Arguments: cmd - command to be restored
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*
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* Returns: Nothing
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*
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* Notes: Immediately prior to retrying a command, we need
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* to restore certain fields that we saved above.
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*/
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void scsi_setup_cmd_retry(struct scsi_cmnd *cmd)
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{
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memcpy(cmd->cmnd, cmd->data_cmnd, sizeof(cmd->data_cmnd));
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cmd->request_buffer = cmd->buffer;
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cmd->request_bufflen = cmd->bufflen;
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cmd->use_sg = cmd->old_use_sg;
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cmd->cmd_len = cmd->old_cmd_len;
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cmd->sc_data_direction = cmd->sc_old_data_direction;
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cmd->underflow = cmd->old_underflow;
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}
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void scsi_device_unbusy(struct scsi_device *sdev)
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{
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struct Scsi_Host *shost = sdev->host;
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unsigned long flags;
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spin_lock_irqsave(shost->host_lock, flags);
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shost->host_busy--;
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if (unlikely(scsi_host_in_recovery(shost) &&
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shost->host_failed))
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scsi_eh_wakeup(shost);
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spin_unlock(shost->host_lock);
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spin_lock(sdev->request_queue->queue_lock);
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sdev->device_busy--;
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spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
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}
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/*
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* Called for single_lun devices on IO completion. Clear starget_sdev_user,
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* and call blk_run_queue for all the scsi_devices on the target -
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* including current_sdev first.
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*
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* Called with *no* scsi locks held.
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*/
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static void scsi_single_lun_run(struct scsi_device *current_sdev)
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{
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struct Scsi_Host *shost = current_sdev->host;
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struct scsi_device *sdev, *tmp;
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struct scsi_target *starget = scsi_target(current_sdev);
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unsigned long flags;
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spin_lock_irqsave(shost->host_lock, flags);
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starget->starget_sdev_user = NULL;
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spin_unlock_irqrestore(shost->host_lock, flags);
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|
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/*
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* Call blk_run_queue for all LUNs on the target, starting with
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* current_sdev. We race with others (to set starget_sdev_user),
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* but in most cases, we will be first. Ideally, each LU on the
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* target would get some limited time or requests on the target.
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*/
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blk_run_queue(current_sdev->request_queue);
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spin_lock_irqsave(shost->host_lock, flags);
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if (starget->starget_sdev_user)
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goto out;
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list_for_each_entry_safe(sdev, tmp, &starget->devices,
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same_target_siblings) {
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if (sdev == current_sdev)
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continue;
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if (scsi_device_get(sdev))
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continue;
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spin_unlock_irqrestore(shost->host_lock, flags);
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blk_run_queue(sdev->request_queue);
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spin_lock_irqsave(shost->host_lock, flags);
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scsi_device_put(sdev);
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}
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out:
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spin_unlock_irqrestore(shost->host_lock, flags);
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}
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|
|
/*
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* Function: scsi_run_queue()
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*
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* Purpose: Select a proper request queue to serve next
|
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*
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* Arguments: q - last request's queue
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*
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* Returns: Nothing
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*
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* Notes: The previous command was completely finished, start
|
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* a new one if possible.
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*/
|
|
static void scsi_run_queue(struct request_queue *q)
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|
{
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struct scsi_device *sdev = q->queuedata;
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struct Scsi_Host *shost = sdev->host;
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unsigned long flags;
|
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|
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if (sdev->single_lun)
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scsi_single_lun_run(sdev);
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spin_lock_irqsave(shost->host_lock, flags);
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while (!list_empty(&shost->starved_list) &&
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!shost->host_blocked && !shost->host_self_blocked &&
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!((shost->can_queue > 0) &&
|
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(shost->host_busy >= shost->can_queue))) {
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/*
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* As long as shost is accepting commands and we have
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* starved queues, call blk_run_queue. scsi_request_fn
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* drops the queue_lock and can add us back to the
|
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* starved_list.
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*
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* host_lock protects the starved_list and starved_entry.
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* scsi_request_fn must get the host_lock before checking
|
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* or modifying starved_list or starved_entry.
|
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*/
|
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sdev = list_entry(shost->starved_list.next,
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struct scsi_device, starved_entry);
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list_del_init(&sdev->starved_entry);
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spin_unlock_irqrestore(shost->host_lock, flags);
|
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|
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blk_run_queue(sdev->request_queue);
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|
|
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.
|
|
* Notes: Upon return, cmd is a stale pointer.
|
|
*/
|
|
static void scsi_requeue_command(struct request_queue *q, struct scsi_cmnd *cmd)
|
|
{
|
|
struct request *req = cmd->request;
|
|
unsigned long flags;
|
|
|
|
scsi_unprep_request(req);
|
|
spin_lock_irqsave(q->queue_lock, flags);
|
|
blk_requeue_request(q, req);
|
|
spin_unlock_irqrestore(q->queue_lock, flags);
|
|
|
|
scsi_run_queue(q);
|
|
}
|
|
|
|
void scsi_next_command(struct scsi_cmnd *cmd)
|
|
{
|
|
struct scsi_device *sdev = cmd->device;
|
|
struct request_queue *q = sdev->request_queue;
|
|
|
|
/* need to hold a reference on the device before we let go of the cmd */
|
|
get_device(&sdev->sdev_gendev);
|
|
|
|
scsi_put_command(cmd);
|
|
scsi_run_queue(q);
|
|
|
|
/* ok to remove device now */
|
|
put_device(&sdev->sdev_gendev);
|
|
}
|
|
|
|
void scsi_run_host_queues(struct Scsi_Host *shost)
|
|
{
|
|
struct scsi_device *sdev;
|
|
|
|
shost_for_each_device(sdev, shost)
|
|
scsi_run_queue(sdev->request_queue);
|
|
}
|
|
|
|
/*
|
|
* 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 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.
|
|
* Notes: If cmd was requeued, upon return it will be a stale pointer.
|
|
*/
|
|
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);
|
|
cmd = NULL;
|
|
}
|
|
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, gfp_t 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);
|
|
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.
|
|
*/
|
|
|
|
/*
|
|
* If the command completed without error, then either
|
|
* finish off the rest of the command, or start a new one.
|
|
*/
|
|
if (scsi_end_request(cmd, 1, good_bytes, result == 0) == 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;
|
|
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 {
|
|
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;
|
|
}
|
|
if (!(req->flags & REQ_QUIET))
|
|
scmd_printk(KERN_INFO, cmd,
|
|
"Device not ready.\n");
|
|
scsi_end_request(cmd, 0, this_count, 1);
|
|
return;
|
|
case VOLUME_OVERFLOW:
|
|
if (!(req->flags & REQ_QUIET)) {
|
|
scmd_printk(KERN_INFO, cmd,
|
|
"Volume overflow, CDB: ");
|
|
__scsi_print_command(cmd->data_cmnd);
|
|
scsi_print_sense("", 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) {
|
|
if (!(req->flags & REQ_QUIET)) {
|
|
scmd_printk(KERN_INFO, cmd,
|
|
"SCSI error: return code = 0x%x\n", 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;
|
|
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)) {
|
|
scsi_unprep_request(req);
|
|
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 void scsi_generic_done(struct scsi_cmnd *cmd)
|
|
{
|
|
BUG_ON(!blk_pc_request(cmd->request));
|
|
scsi_io_completion(cmd, cmd->result == 0 ? cmd->bufflen : 0, 0);
|
|
}
|
|
|
|
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))) {
|
|
sdev_printk(KERN_ERR, sdev,
|
|
"rejecting I/O to offline device\n");
|
|
goto 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 */
|
|
sdev_printk(KERN_ERR, sdev,
|
|
"rejecting I/O to dead device\n");
|
|
goto 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 && 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) && !(req->flags & REQ_SPECIAL)) {
|
|
if(specials_only == SDEV_QUIESCE ||
|
|
specials_only == SDEV_BLOCK)
|
|
goto defer;
|
|
|
|
sdev_printk(KERN_ERR, sdev,
|
|
"rejecting I/O to device being removed\n");
|
|
goto 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");
|
|
goto 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);
|
|
switch(ret) {
|
|
/* For BLKPREP_KILL/DEFER the cmd was released */
|
|
case BLKPREP_KILL:
|
|
goto kill;
|
|
case BLKPREP_DEFER:
|
|
goto defer;
|
|
}
|
|
|
|
/*
|
|
* Initialize the actual SCSI command for this request.
|
|
*/
|
|
if (req->rq_disk) {
|
|
drv = *(struct scsi_driver **)req->rq_disk->private_data;
|
|
if (unlikely(!drv->init_command(cmd))) {
|
|
scsi_release_buffers(cmd);
|
|
scsi_put_command(cmd);
|
|
goto kill;
|
|
}
|
|
} else {
|
|
memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
|
|
cmd->cmd_len = req->cmd_len;
|
|
if (rq_data_dir(req) == WRITE)
|
|
cmd->sc_data_direction = DMA_TO_DEVICE;
|
|
else if (req->data_len)
|
|
cmd->sc_data_direction = DMA_FROM_DEVICE;
|
|
else
|
|
cmd->sc_data_direction = DMA_NONE;
|
|
|
|
cmd->transfersize = req->data_len;
|
|
cmd->allowed = 3;
|
|
cmd->timeout_per_command = req->timeout;
|
|
cmd->done = scsi_generic_done;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
kill:
|
|
req->errors = DID_NO_CONNECT << 16;
|
|
return BLKPREP_KILL;
|
|
}
|
|
|
|
/*
|
|
* 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,
|
|
sdev_printk(KERN_INFO, sdev,
|
|
"unblocking device at zero depth\n"));
|
|
} 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 (scsi_host_in_recovery(shost))
|
|
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 a request for a dead device
|
|
*/
|
|
static void scsi_kill_request(struct request *req, request_queue_t *q)
|
|
{
|
|
struct scsi_cmnd *cmd = req->special;
|
|
|
|
blkdev_dequeue_request(req);
|
|
|
|
if (unlikely(cmd == NULL)) {
|
|
printk(KERN_CRIT "impossible request in %s.\n",
|
|
__FUNCTION__);
|
|
BUG();
|
|
}
|
|
|
|
scsi_init_cmd_errh(cmd);
|
|
cmd->result = DID_NO_CONNECT << 16;
|
|
atomic_inc(&cmd->device->iorequest_cnt);
|
|
__scsi_done(cmd);
|
|
}
|
|
|
|
/*
|
|
* 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");
|
|
while ((req = elv_next_request(q)) != NULL)
|
|
scsi_kill_request(req, 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))) {
|
|
sdev_printk(KERN_ERR, sdev,
|
|
"rejecting I/O to offline device\n");
|
|
scsi_kill_request(req, q);
|
|
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);
|
|
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();
|
|
}
|
|
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);
|
|
|
|
/*
|
|
* 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, NULL);
|
|
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.
|
|
* @sdev: SCSI device to be queried
|
|
* @dbd: set if mode sense will allow block descriptors to be returned
|
|
* @modepage: mode page being requested
|
|
* @buffer: request buffer (may not be smaller than eight bytes)
|
|
* @len: length of request buffer.
|
|
* @timeout: command timeout
|
|
* @retries: number of retries before failing
|
|
* @data: returns a structure abstracting the mode header data
|
|
* @sense: place to put sense data (or NULL if no sense to be collected).
|
|
* must be SCSI_SENSE_BUFFERSIZE big.
|
|
*
|
|
* Returns zero if unsuccessful, or the header offset (either 4
|
|
* or 8 depending on whether a six or ten byte command was
|
|
* issued) if successful.
|
|
**/
|
|
int
|
|
scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
|
|
unsigned char *buffer, int len, int timeout, int retries,
|
|
struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr) {
|
|
unsigned char cmd[12];
|
|
int use_10_for_ms;
|
|
int header_length;
|
|
int result;
|
|
struct scsi_sense_hdr my_sshdr;
|
|
|
|
memset(data, 0, sizeof(*data));
|
|
memset(&cmd[0], 0, 12);
|
|
cmd[1] = dbd & 0x18; /* allows DBD and LLBA bits */
|
|
cmd[2] = modepage;
|
|
|
|
/* caller might not be interested in sense, but we need it */
|
|
if (!sshdr)
|
|
sshdr = &my_sshdr;
|
|
|
|
retry:
|
|
use_10_for_ms = sdev->use_10_for_ms;
|
|
|
|
if (use_10_for_ms) {
|
|
if (len < 8)
|
|
len = 8;
|
|
|
|
cmd[0] = MODE_SENSE_10;
|
|
cmd[8] = len;
|
|
header_length = 8;
|
|
} else {
|
|
if (len < 4)
|
|
len = 4;
|
|
|
|
cmd[0] = MODE_SENSE;
|
|
cmd[4] = len;
|
|
header_length = 4;
|
|
}
|
|
|
|
memset(buffer, 0, len);
|
|
|
|
result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
|
|
sshdr, timeout, retries);
|
|
|
|
/* This code looks awful: what it's doing is making sure an
|
|
* ILLEGAL REQUEST sense return identifies the actual command
|
|
* byte as the problem. MODE_SENSE commands can return
|
|
* ILLEGAL REQUEST if the code page isn't supported */
|
|
|
|
if (use_10_for_ms && !scsi_status_is_good(result) &&
|
|
(driver_byte(result) & DRIVER_SENSE)) {
|
|
if (scsi_sense_valid(sshdr)) {
|
|
if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
|
|
(sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
|
|
/*
|
|
* Invalid command operation code
|
|
*/
|
|
sdev->use_10_for_ms = 0;
|
|
goto retry;
|
|
}
|
|
}
|
|
}
|
|
|
|
if(scsi_status_is_good(result)) {
|
|
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 result;
|
|
}
|
|
EXPORT_SYMBOL(scsi_mode_sense);
|
|
|
|
int
|
|
scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
|
|
{
|
|
char cmd[] = {
|
|
TEST_UNIT_READY, 0, 0, 0, 0, 0,
|
|
};
|
|
struct scsi_sense_hdr sshdr;
|
|
int result;
|
|
|
|
result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, &sshdr,
|
|
timeout, retries);
|
|
|
|
if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
|
|
|
|
if ((scsi_sense_valid(&sshdr)) &&
|
|
((sshdr.sense_key == UNIT_ATTENTION) ||
|
|
(sshdr.sense_key == NOT_READY))) {
|
|
sdev->changed = 1;
|
|
result = 0;
|
|
}
|
|
}
|
|
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,
|
|
sdev_printk(KERN_ERR, sdev,
|
|
"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);
|