/*
* 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 }
static 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
static void scsi_run_queue(struct request_queue *q);
/*
* Function: scsi_unprep_request()
*
* Purpose: Remove all preparation done for a request, including its
* associated scsi_cmnd, so that it can be requeued.
*
* Arguments: req - request to unprepare
*
* Lock status: Assumed that no locks are held upon entry.
*
* Returns: Nothing.
*/
static void scsi_unprep_request(struct request *req)
{
struct scsi_cmnd *cmd = req->special;
req->flags &= ~REQ_DONTPREP;
req->special = (req->flags & REQ_SPECIAL) ? cmd->sc_request : NULL;
scsi_put_command(cmd);
}
/*
* 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;
struct request_queue *q = device->request_queue;
unsigned long flags;
SCSI_LOG_MLQUEUE(1,
printk("Inserting command %p into mlqueue\n", cmd));
/*
* 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;
/*
* Decrement the counters, since these commands are no longer
* active on the host/device.
*/
scsi_device_unbusy(device);
/*
* Requeue this command. 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 we *don't* plug the queue, we call the request
* function. The SCSI request function detects the blocked condition
* and plugs the queue appropriately.
*/
spin_lock_irqsave(q->queue_lock, flags);
blk_requeue_request(q, cmd->request);
spin_unlock_irqrestore(q->queue_lock, flags);
scsi_run_queue(q);
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
*
* 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,
1, sreq);
}
EXPORT_SYMBOL(scsi_do_req);
/**
* scsi_execute - insert request and wait for the result
* @sdev: scsi device
* @cmd: scsi command
* @data_direction: data direction
* @buffer: data buffer
* @bufflen: len of buffer
* @sense: optional sense buffer
* @timeout: request timeout in seconds
* @retries: number of times to retry request
* @flags: or into request flags;
*
* returns the req->errors value which is the the scsi_cmnd result
* field.
**/
int scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
int data_direction, void *buffer, unsigned bufflen,
unsigned char *sense, int timeout, int retries, int flags)
{
struct request *req;
int write = (data_direction == DMA_TO_DEVICE);
int ret = DRIVER_ERROR << 24;
req = blk_get_request(sdev->request_queue, write, __GFP_WAIT);
if (bufflen && blk_rq_map_kern(sdev->request_queue, req,
buffer, bufflen, __GFP_WAIT))
goto out;
req->cmd_len = COMMAND_SIZE(cmd[0]);
memcpy(req->cmd, cmd, req->cmd_len);
req->sense = sense;
req->sense_len = 0;
req->retries = retries;
req->timeout = timeout;
req->flags |= flags | REQ_BLOCK_PC | REQ_SPECIAL | REQ_QUIET;
/*
* head injection *required* here otherwise quiesce won't work
*/
blk_execute_rq(req->q, NULL, req, 1);
ret = req->errors;
out:
blk_put_request(req);
return ret;
}
EXPORT_SYMBOL(scsi_execute);
int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,
int data_direction, void *buffer, unsigned bufflen,
struct scsi_sense_hdr *sshdr, int timeout, int retries)
{
char *sense = NULL;
int result;
if (sshdr) {
sense = kmalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
if (!sense)
return DRIVER_ERROR << 24;
memset(sense, 0, SCSI_SENSE_BUFFERSIZE);
}
result = scsi_execute(sdev, cmd, data_direction, buffer, bufflen,
sense, timeout, retries, 0);
if (sshdr)
scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
kfree(sense);
return result;
}
EXPORT_SYMBOL(scsi_execute_req);
struct scsi_io_context {
void *data;
void (*done)(void *data, char *sense, int result, int resid);
char sense[SCSI_SENSE_BUFFERSIZE];
};
static kmem_cache_t *scsi_io_context_cache;
static void scsi_end_async(struct request *req)
{
struct scsi_io_context *sioc = req->end_io_data;
if (sioc->done)
sioc->done(sioc->data, sioc->sense, req->errors, req->data_len);
kmem_cache_free(scsi_io_context_cache, sioc);
__blk_put_request(req->q, req);
}
static int scsi_merge_bio(struct request *rq, struct bio *bio)
{
struct request_queue *q = rq->q;
bio->bi_flags &= ~(1 << BIO_SEG_VALID);
if (rq_data_dir(rq) == WRITE)
bio->bi_rw |= (1 << BIO_RW);
blk_queue_bounce(q, &bio);
if (!rq->bio)
blk_rq_bio_prep(q, rq, bio);
else if (!q->back_merge_fn(q, rq, bio))
return -EINVAL;
else {
rq->biotail->bi_next = bio;
rq->biotail = bio;
rq->hard_nr_sectors += bio_sectors(bio);
rq->nr_sectors = rq->hard_nr_sectors;
}
return 0;
}
static int scsi_bi_endio(struct bio *bio, unsigned int bytes_done, int error)
{
if (bio->bi_size)
return 1;
bio_put(bio);
return 0;
}
/**
* scsi_req_map_sg - map a scatterlist into a request
* @rq: request to fill
* @sg: scatterlist
* @nsegs: number of elements
* @bufflen: len of buffer
* @gfp: memory allocation flags
*
* scsi_req_map_sg maps a scatterlist into a request so that the
* request can be sent to the block layer. We do not trust the scatterlist
* sent to use, as some ULDs use that struct to only organize the pages.
*/
static int scsi_req_map_sg(struct request *rq, struct scatterlist *sgl,
int nsegs, unsigned bufflen, gfp_t gfp)
{
struct request_queue *q = rq->q;
int nr_pages = (bufflen + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned int data_len = 0, len, bytes, off;
struct page *page;
struct bio *bio = NULL;
int i, err, nr_vecs = 0;
for (i = 0; i < nsegs; i++) {
page = sgl[i].page;
off = sgl[i].offset;
len = sgl[i].length;
data_len += len;
while (len > 0) {
bytes = min_t(unsigned int, len, PAGE_SIZE - off);
if (!bio) {
nr_vecs = min_t(int, BIO_MAX_PAGES, nr_pages);
nr_pages -= nr_vecs;
bio = bio_alloc(gfp, nr_vecs);
if (!bio) {
err = -ENOMEM;
goto free_bios;
}
bio->bi_end_io = scsi_bi_endio;
}
if (bio_add_pc_page(q, bio, page, bytes, off) !=
bytes) {
bio_put(bio);
err = -EINVAL;
goto free_bios;
}
if (bio->bi_vcnt >= nr_vecs) {
err = scsi_merge_bio(rq, bio);
if (err) {
bio_endio(bio, bio->bi_size, 0);
goto free_bios;
}
bio = NULL;
}
page++;
len -= bytes;
off = 0;
}
}
rq->buffer = rq->data = NULL;
rq->data_len = data_len;
return 0;
free_bios:
while ((bio = rq->bio) != NULL) {
rq->bio = bio->bi_next;
/*
* call endio instead of bio_put incase it was bounced
*/
bio_endio(bio, bio->bi_size, 0);
}
return err;
}
/**
* scsi_execute_async - insert request
* @sdev: scsi device
* @cmd: scsi command
* @data_direction: data direction
* @buffer: data buffer (this can be a kernel buffer or scatterlist)
* @bufflen: len of buffer
* @use_sg: if buffer is a scatterlist this is the number of elements
* @timeout: request timeout in seconds
* @retries: number of times to retry request
* @flags: or into request flags
**/
int scsi_execute_async(struct scsi_device *sdev, const unsigned char *cmd,
int data_direction, void *buffer, unsigned bufflen,
int use_sg, int timeout, int retries, void *privdata,
void (*done)(void *, char *, int, int), gfp_t gfp)
{
struct request *req;
struct scsi_io_context *sioc;
int err = 0;
int write = (data_direction == DMA_TO_DEVICE);
sioc = kmem_cache_alloc(scsi_io_context_cache, gfp);
if (!sioc)
return DRIVER_ERROR << 24;
memset(sioc, 0, sizeof(*sioc));
req = blk_get_request(sdev->request_queue, write, gfp);
if (!req)
goto free_sense;
req->flags |= REQ_BLOCK_PC | REQ_QUIET;
if (use_sg)
err = scsi_req_map_sg(req, buffer, use_sg, bufflen, gfp);
else if (bufflen)
err = blk_rq_map_kern(req->q, req, buffer, bufflen, gfp);
if (err)
goto free_req;
req->cmd_len = COMMAND_SIZE(cmd[0]);
memcpy(req->cmd, cmd, req->cmd_len);
req->sense = sioc->sense;
req->sense_len = 0;
req->timeout = timeout;
req->retries = retries;
req->end_io_data = sioc;
sioc->data = privdata;
sioc->done = done;
blk_execute_rq_nowait(req->q, NULL, req, 1, scsi_end_async);
return 0;
free_req:
blk_put_request(req);
free_sense:
kfree(sioc);
return DRIVER_ERROR << 24;
}
EXPORT_SYMBOL_GPL(scsi_execute_async);
/*
* 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->serial_number = 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;
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(scsi_host_in_recovery(shost) &&
shost->host_failed))
scsi_eh_wakeup(shost);
spin_unlock(shost->host_lock);
spin_lock(sdev->request_queue->queue_lock);
sdev->device_busy--;
spin_unlock_irqrestore(sdev->request_queue->queue_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.
* 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, uptodate);
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 &&
sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
(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));
/*
* This will complete the whole command with uptodate=1 so
* as far as the block layer is concerned the command completed
* successfully. Since this is a REQ_BLOCK_PC command the
* caller should check the request's errors value
*/
scsi_io_completion(cmd, cmd->bufflen, 0);
}
void scsi_setup_blk_pc_cmnd(struct scsi_cmnd *cmd)
{
struct request *req = cmd->request;
BUG_ON(sizeof(req->cmd) > sizeof(cmd->cmnd));
memcpy(cmd->cmnd, req->cmd, sizeof(cmd->cmnd));
cmd->cmd_len = req->cmd_len;
if (!req->data_len)
cmd->sc_data_direction = DMA_NONE;
else if (rq_data_dir(req) == WRITE)
cmd->sc_data_direction = DMA_TO_DEVICE;
else
cmd->sc_data_direction = DMA_FROM_DEVICE;
cmd->transfersize = req->data_len;
cmd->allowed = req->retries;
cmd->timeout_per_command = req->timeout;
}
EXPORT_SYMBOL_GPL(scsi_setup_blk_pc_cmnd);
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 {
scsi_setup_blk_pc_cmnd(cmd);
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;
scsi_io_context_cache = kmem_cache_create("scsi_io_context",
sizeof(struct scsi_io_context),
0, 0, NULL, NULL);
if (!scsi_io_context_cache) {
printk(KERN_ERR "SCSI: can't init scsi io context cache\n");
return -ENOMEM;
}
for (i = 0; i < SG_MEMPOOL_NR; i++) {
struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
int size = sgp->size * sizeof(struct scatterlist);
sgp->slab = kmem_cache_create(sgp->name, size, 0,
SLAB_HWCACHE_ALIGN, NULL, 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;
kmem_cache_destroy(scsi_io_context_cache);
for (i = 0; i < SG_MEMPOOL_NR; i++) {
struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
mempool_destroy(sgp->pool);
kmem_cache_destroy(sgp->slab);
}
}
/**
* scsi_mode_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);
