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c46f2334c8
linux/drivers/scsi/scsi_lib.c
Jens Axboe c46f2334c8 [SG] Get rid of __sg_mark_end() 
sg_mark_end() overwrites the page_link information, but all users want
__sg_mark_end() behaviour where we just set the end bit. That is the most
natural way to use the sg list, since you'll fill it in and then mark the
end point.

So change sg_mark_end() to only set the termination bit. Add a sg_magic
debug check as well, and clear a chain pointer if it is set.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2007-11-02 08:47:06 +01:00

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/*
* 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 <linux/hardirq.h>
#include <linux/scatterlist.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include "scsi_priv.h"
#include "scsi_logging.h"
#define SG_MEMPOOL_NR ARRAY_SIZE(scsi_sg_pools)
#define SG_MEMPOOL_SIZE 2
/*
* The maximum number of SG segments that we will put inside a scatterlist
* (unless chaining is used). Should ideally fit inside a single page, to
* avoid a higher order allocation.
*/
#define SCSI_MAX_SG_SEGMENTS 128
struct scsi_host_sg_pool {
size_t size;
char *name;
struct kmem_cache *slab;
mempool_t *pool;
};
#define SP(x) { x, "sgpool-" #x }
static struct scsi_host_sg_pool scsi_sg_pools[] = {
SP(8),
SP(16),
#if (SCSI_MAX_SG_SEGMENTS > 16)
SP(32),
#if (SCSI_MAX_SG_SEGMENTS > 32)
SP(64),
#if (SCSI_MAX_SG_SEGMENTS > 64)
SP(128),
#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->cmd_flags &= ~REQ_DONTPREP;
req->special = 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;
}
/**
* 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 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->cmd_type = REQ_TYPE_BLOCK_PC;
req->cmd_flags |= flags | REQ_QUIET | REQ_PREEMPT;
/*
* head injection *required* here otherwise quiesce won't work
*/
blk_execute_rq(req->q, NULL, req, 1);
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 = kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_NOIO);
if (!sense)
return DRIVER_ERROR << 24;
}
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 struct kmem_cache *scsi_io_context_cache;
static void scsi_end_async(struct request *req, int uptodate)
{
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);
return blk_rq_append_bio(q, rq, bio);
}
static void scsi_bi_endio(struct bio *bio, int error)
{
bio_put(bio);
}
/**
* 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 + sgl[0].offset + PAGE_SIZE - 1) >> PAGE_SHIFT;
unsigned int data_len = bufflen, len, bytes, off;
struct scatterlist *sg;
struct page *page;
struct bio *bio = NULL;
int i, err, nr_vecs = 0;
for_each_sg(sgl, sg, nsegs, i) {
page = sg_page(sg);
off = sg->offset;
len = sg->length;
data_len += len;
while (len > 0 && data_len > 0) {
/*
* sg sends a scatterlist that is larger than
* the data_len it wants transferred for certain
* IO sizes
*/
bytes = min_t(unsigned int, len, PAGE_SIZE - off);
bytes = min(bytes, data_len);
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, 0);
goto free_bios;
}
bio = NULL;
}
page++;
len -= bytes;
data_len -=bytes;
off = 0;
}
}
rq->buffer = rq->data = NULL;
rq->data_len = bufflen;
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, 0);
}
return err;
}
/**
* scsi_execute_async - insert request
* @sdev: scsi device
* @cmd: scsi command
* @cmd_len: length of scsi cdb
* @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 cmd_len, 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_zalloc(scsi_io_context_cache, gfp);
if (!sioc)
return DRIVER_ERROR << 24;
req = blk_get_request(sdev->request_queue, write, gfp);
if (!req)
goto free_sense;
req->cmd_type = REQ_TYPE_BLOCK_PC;
req->cmd_flags |= 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 = cmd_len;
memset(req->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
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:
kmem_cache_free(scsi_io_context_cache, 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.
*
* Notes: This function has the job of initializing a number of
* fields related to error handling. Typically this will
* be called once for each command, as required.
*/
static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
{
cmd->serial_number = 0;
cmd->resid = 0;
memset(cmd->sense_buffer, 0, sizeof cmd->sense_buffer);
if (cmd->cmd_len == 0)
cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
}
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 || shost->host_eh_scheduled)))
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);
if (test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
!test_and_set_bit(QUEUE_FLAG_REENTER,
&sdev->request_queue->queue_flags)) {
blk_run_queue(sdev->request_queue);
clear_bit(QUEUE_FLAG_REENTER,
&sdev->request_queue->queue_flags);
} else
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)
{
struct request_queue *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;
}
/*
* Like SCSI_MAX_SG_SEGMENTS, but for archs that have sg chaining. This limit
* is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
*/
#define SCSI_MAX_SG_CHAIN_SEGMENTS 2048
static inline unsigned int scsi_sgtable_index(unsigned short nents)
{
unsigned int index;
switch (nents) {
case 1 ... 8:
index = 0;
break;
case 9 ... 16:
index = 1;
break;
#if (SCSI_MAX_SG_SEGMENTS > 16)
case 17 ... 32:
index = 2;
break;
#if (SCSI_MAX_SG_SEGMENTS > 32)
case 33 ... 64:
index = 3;
break;
#if (SCSI_MAX_SG_SEGMENTS > 64)
case 65 ... 128:
index = 4;
break;
#endif
#endif
#endif
default:
printk(KERN_ERR "scsi: bad segment count=%d\n", nents);
BUG();
}
return index;
}
struct scatterlist *scsi_alloc_sgtable(struct scsi_cmnd *cmd, gfp_t gfp_mask)
{
struct scsi_host_sg_pool *sgp;
struct scatterlist *sgl, *prev, *ret;
unsigned int index;
int this, left;
BUG_ON(!cmd->use_sg);
left = cmd->use_sg;
ret = prev = NULL;
do {
this = left;
if (this > SCSI_MAX_SG_SEGMENTS) {
this = SCSI_MAX_SG_SEGMENTS - 1;
index = SG_MEMPOOL_NR - 1;
} else
index = scsi_sgtable_index(this);
left -= this;
sgp = scsi_sg_pools + index;
sgl = mempool_alloc(sgp->pool, gfp_mask);
if (unlikely(!sgl))
goto enomem;
sg_init_table(sgl, sgp->size);
/*
* first loop through, set initial index and return value
*/
if (!ret)
ret = sgl;
/*
* chain previous sglist, if any. we know the previous
* sglist must be the biggest one, or we would not have
* ended up doing another loop.
*/
if (prev)
sg_chain(prev, SCSI_MAX_SG_SEGMENTS, sgl);
/*
* if we have nothing left, mark the last segment as
* end-of-list
*/
if (!left)
sg_mark_end(&sgl[this - 1]);
/*
* don't allow subsequent mempool allocs to sleep, it would
* violate the mempool principle.
*/
gfp_mask &= ~__GFP_WAIT;
gfp_mask |= __GFP_HIGH;
prev = sgl;
} while (left);
/*
* ->use_sg may get modified after dma mapping has potentially
* shrunk the number of segments, so keep a copy of it for free.
*/
cmd->__use_sg = cmd->use_sg;
return ret;
enomem:
if (ret) {
/*
* Free entries chained off ret. Since we were trying to
* allocate another sglist, we know that all entries are of
* the max size.
*/
sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
prev = ret;
ret = &ret[SCSI_MAX_SG_SEGMENTS - 1];
while ((sgl = sg_chain_ptr(ret)) != NULL) {
ret = &sgl[SCSI_MAX_SG_SEGMENTS - 1];
mempool_free(sgl, sgp->pool);
}
mempool_free(prev, sgp->pool);
}
return NULL;
}
EXPORT_SYMBOL(scsi_alloc_sgtable);
void scsi_free_sgtable(struct scsi_cmnd *cmd)
{
struct scatterlist *sgl = cmd->request_buffer;
struct scsi_host_sg_pool *sgp;
/*
* if this is the biggest size sglist, check if we have
* chained parts we need to free
*/
if (cmd->__use_sg > SCSI_MAX_SG_SEGMENTS) {
unsigned short this, left;
struct scatterlist *next;
unsigned int index;
left = cmd->__use_sg - (SCSI_MAX_SG_SEGMENTS - 1);
next = sg_chain_ptr(&sgl[SCSI_MAX_SG_SEGMENTS - 1]);
while (left && next) {
sgl = next;
this = left;
if (this > SCSI_MAX_SG_SEGMENTS) {
this = SCSI_MAX_SG_SEGMENTS - 1;
index = SG_MEMPOOL_NR - 1;
} else
index = scsi_sgtable_index(this);
left -= this;
sgp = scsi_sg_pools + index;
if (left)
next = sg_chain_ptr(&sgl[sgp->size - 1]);
mempool_free(sgl, sgp->pool);
}
/*
* Restore original, will be freed below
*/
sgl = cmd->request_buffer;
sgp = scsi_sg_pools + SG_MEMPOOL_NR - 1;
} else
sgp = scsi_sg_pools + scsi_sgtable_index(cmd->__use_sg);
mempool_free(sgl, sgp->pool);
}
EXPORT_SYMBOL(scsi_free_sgtable);
/*
* 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)
{
if (cmd->use_sg)
scsi_free_sgtable(cmd);
/*
* Zero these out. They now point to freed memory, and it is
* dangerous to hang onto the pointers.
*/
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)
{
int result = cmd->result;
int this_count = cmd->request_bufflen;
struct request_queue *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;
scsi_release_buffers(cmd);
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;
}
}
req->data_len = cmd->resid;
}
/*
* Next deal with any sectors which we were able to correctly
* handle.
*/
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;
/* A number of bytes were successfully read. If there
* are leftovers and there is some kind of error
* (result != 0), retry the rest.
*/
if (scsi_end_request(cmd, 1, good_bytes, result == 0) == NULL)
return;
/* good_bytes = 0, or (inclusive) there were leftovers and
* result = 0, so scsi_end_request couldn't retry.
*/
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);
return;
} else {
scsi_end_request(cmd, 0, this_count, 1);
return;
}
break;
case NOT_READY:
/* If the device is in the process of becoming
* ready, or has a temporary blockage, retry.
*/
if (sshdr.asc == 0x04) {
switch (sshdr.ascq) {
case 0x01: /* becoming ready */
case 0x04: /* format in progress */
case 0x05: /* rebuild in progress */
case 0x06: /* recalculation in progress */
case 0x07: /* operation in progress */
case 0x08: /* Long write in progress */
case 0x09: /* self test in progress */
scsi_requeue_command(q, cmd);
return;
default:
break;
}
}
if (!(req->cmd_flags & REQ_QUIET))
scsi_cmd_print_sense_hdr(cmd,
"Device not ready",
&sshdr);
scsi_end_request(cmd, 0, this_count, 1);
return;
case VOLUME_OVERFLOW:
if (!(req->cmd_flags & REQ_QUIET)) {
scmd_printk(KERN_INFO, cmd,
"Volume overflow, CDB: ");
__scsi_print_command(cmd->cmnd);
scsi_print_sense("", cmd);
}
/* See SSC3rXX or current. */
scsi_end_request(cmd, 0, this_count, 1);
return;
default:
break;
}
}
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->cmd_flags & REQ_QUIET)) {
scsi_print_result(cmd);
if (driver_byte(result) & DRIVER_SENSE)
scsi_print_sense("", cmd);
}
}
scsi_end_request(cmd, 0, this_count, !result);
}
/*
* 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;
int count;
/*
* 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.
*/
cmd->request_buffer = scsi_alloc_sgtable(cmd, GFP_ATOMIC);
if (unlikely(!cmd->request_buffer)) {
scsi_unprep_request(req);
return BLKPREP_DEFER;
}
req->buffer = NULL;
if (blk_pc_request(req))
cmd->request_bufflen = req->data_len;
else
cmd->request_bufflen = req->nr_sectors << 9;
/*
* 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);
if (likely(count <= cmd->use_sg)) {
cmd->use_sg = count;
return BLKPREP_OK;
}
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);
return BLKPREP_KILL;
}
static struct scsi_cmnd *scsi_get_cmd_from_req(struct scsi_device *sdev,
struct request *req)
{
struct scsi_cmnd *cmd;
if (!req->special) {
cmd = scsi_get_command(sdev, GFP_ATOMIC);
if (unlikely(!cmd))
return NULL;
req->special = cmd;
} else {
cmd = req->special;
}
/* pull a tag out of the request if we have one */
cmd->tag = req->tag;
cmd->request = req;
return cmd;
}
int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
{
struct scsi_cmnd *cmd;
int ret = scsi_prep_state_check(sdev, req);
if (ret != BLKPREP_OK)
return ret;
cmd = scsi_get_cmd_from_req(sdev, req);
if (unlikely(!cmd))
return BLKPREP_DEFER;
/*
* BLOCK_PC requests may transfer data, in which case they must
* a bio attached to them. Or they might contain a SCSI command
* that does not transfer data, in which case they may optionally
* submit a request without an attached bio.
*/
if (req->bio) {
int ret;
BUG_ON(!req->nr_phys_segments);
ret = scsi_init_io(cmd);
if (unlikely(ret))
return ret;
} else {
BUG_ON(req->data_len);
BUG_ON(req->data);
cmd->request_bufflen = 0;
cmd->request_buffer = NULL;
cmd->use_sg = 0;
req->buffer = NULL;
}
BUILD_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;
return BLKPREP_OK;
}
EXPORT_SYMBOL(scsi_setup_blk_pc_cmnd);
/*
* Setup a REQ_TYPE_FS command. These are simple read/write request
* from filesystems that still need to be translated to SCSI CDBs from
* the ULD.
*/
int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
{
struct scsi_cmnd *cmd;
int ret = scsi_prep_state_check(sdev, req);
if (ret != BLKPREP_OK)
return ret;
/*
* Filesystem requests must transfer data.
*/
BUG_ON(!req->nr_phys_segments);
cmd = scsi_get_cmd_from_req(sdev, req);
if (unlikely(!cmd))
return BLKPREP_DEFER;
return scsi_init_io(cmd);
}
EXPORT_SYMBOL(scsi_setup_fs_cmnd);
int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
{
int ret = BLKPREP_OK;
/*
* If the device is not in running state we will reject some
* or all commands.
*/
if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
switch (sdev->sdev_state) {
case SDEV_OFFLINE:
/*
* If the device is offline we refuse to process any
* commands. The device must be brought online
* before trying any recovery commands.
*/
sdev_printk(KERN_ERR, sdev,
"rejecting I/O to offline device\n");
ret = BLKPREP_KILL;
break;
case SDEV_DEL:
/*
* If the device is fully deleted, we refuse to
* process any commands as well.
*/
sdev_printk(KERN_ERR, sdev,
"rejecting I/O to dead device\n");
ret = BLKPREP_KILL;
break;
case SDEV_QUIESCE:
case SDEV_BLOCK:
/*
* If the devices is blocked we defer normal commands.
*/
if (!(req->cmd_flags & REQ_PREEMPT))
ret = BLKPREP_DEFER;
break;
default:
/*
* For any other not fully online state we only allow
* special commands. In particular any user initiated
* command is not allowed.
*/
if (!(req->cmd_flags & REQ_PREEMPT))
ret = BLKPREP_KILL;
break;
}
}
return ret;
}
EXPORT_SYMBOL(scsi_prep_state_check);
int scsi_prep_return(struct request_queue *q, struct request *req, int ret)
{
struct scsi_device *sdev = q->queuedata;
switch (ret) {
case BLKPREP_KILL:
req->errors = DID_NO_CONNECT << 16;
/* release the command and kill it */
if (req->special) {
struct scsi_cmnd *cmd = req->special;
scsi_release_buffers(cmd);
scsi_put_command(cmd);
req->special = NULL;
}
break;
case BLKPREP_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);
break;
default:
req->cmd_flags |= REQ_DONTPREP;
}
return ret;
}
EXPORT_SYMBOL(scsi_prep_return);
static int scsi_prep_fn(struct request_queue *q, struct request *req)
{
struct scsi_device *sdev = q->queuedata;
int ret = BLKPREP_KILL;
if (req->cmd_type == REQ_TYPE_BLOCK_PC)
ret = scsi_setup_blk_pc_cmnd(sdev, req);
return scsi_prep_return(q, req, ret);
}
/*
* 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, struct request_queue *q)
{
struct scsi_cmnd *cmd = req->special;
struct scsi_device *sdev = cmd->device;
struct Scsi_Host *shost = sdev->host;
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 request completion path will do scsi_device_unbusy(),
* bump busy counts. To bump the counters, we need to dance
* with the locks as normal issue path does.
*/
sdev->device_busy++;
spin_unlock(sdev->request_queue->queue_lock);
spin_lock(shost->host_lock);
shost->host_busy++;
spin_unlock(shost->host_lock);
spin_lock(sdev->request_queue->queue_lock);
__scsi_done(cmd);
}
static void scsi_softirq_done(struct request *rq)
{
struct scsi_cmnd *cmd = rq->completion_data;
unsigned long wait_for = (cmd->allowed + 1) * cmd->timeout_per_command;
int disposition;
INIT_LIST_HEAD(&cmd->eh_entry);
disposition = scsi_decide_disposition(cmd);
if (disposition != SUCCESS &&
time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
sdev_printk(KERN_ERR, cmd->device,
"timing out command, waited %lus\n",
wait_for/HZ);
disposition = SUCCESS;
}
scsi_log_completion(cmd, disposition);
switch (disposition) {
case SUCCESS:
scsi_finish_command(cmd);
break;
case NEEDS_RETRY:
scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
break;
case ADD_TO_MLQUEUE:
scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
break;
default:
if (!scsi_eh_scmd_add(cmd, 0))
scsi_finish_command(cmd);
}
}
/*
* 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\n",
__FUNCTION__);
blk_dump_rq_flags(req, "foo");
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_Host *shost,
request_fn_proc *request_fn)
{
struct request_queue *q;
q = blk_init_queue(request_fn, NULL);
if (!q)
return NULL;
/*
* this limit is imposed by hardware restrictions
*/
blk_queue_max_hw_segments(q, shost->sg_tablesize);
/*
* In the future, sg chaining support will be mandatory and this
* ifdef can then go away. Right now we don't have all archs
* converted, so better keep it safe.
*/
#ifdef ARCH_HAS_SG_CHAIN
if (shost->use_sg_chaining)
blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_SEGMENTS);
else
blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
#else
blk_queue_max_phys_segments(q, SCSI_MAX_SG_SEGMENTS);
#endif
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);
if (!shost->use_clustering)
clear_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
return q;
}
EXPORT_SYMBOL(__scsi_alloc_queue);
struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
{
struct request_queue *q;
q = __scsi_alloc_queue(sdev->host, scsi_request_fn);
if (!q)
return NULL;
blk_queue_prep_rq(q, scsi_prep_fn);
blk_queue_softirq_done(q, scsi_softirq_done);
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);
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);
if (!sgp->slab) {
printk(KERN_ERR "SCSI: can't init sg slab %s\n",
sgp->name);
}
sgp->pool = mempool_create_slab_pool(SG_MEMPOOL_SIZE,
sgp->slab);
if (!sgp->pool) {
printk(KERN_ERR "SCSI: can't init sg mempool %s\n",
sgp->name);
}
}
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_select - issue a mode select
* @sdev: SCSI device to be queried
* @pf: Page format bit (1 == standard, 0 == vendor specific)
* @sp: Save page bit (0 == don't save, 1 == save)
* @modepage: mode page being requested
* @buffer: request buffer (may not be smaller than eight bytes)
* @len: length of request buffer.
* @timeout: command timeout
* @retries: number of retries before failing
* @data: returns a structure abstracting the mode header data
* @sense: place to put sense data (or NULL if no sense to be collected).
* must be SCSI_SENSE_BUFFERSIZE big.
*
* Returns zero if successful; negative error number or scsi
* status on error
*
*/
int
scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
unsigned char *buffer, int len, int timeout, int retries,
struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
{
unsigned char cmd[10];
unsigned char *real_buffer;
int ret;
memset(cmd, 0, sizeof(cmd));
cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
if (sdev->use_10_for_ms) {
if (len > 65535)
return -EINVAL;
real_buffer = kmalloc(8 + len, GFP_KERNEL);
if (!real_buffer)
return -ENOMEM;
memcpy(real_buffer + 8, buffer, len);
len += 8;
real_buffer[0] = 0;
real_buffer[1] = 0;
real_buffer[2] = data->medium_type;
real_buffer[3] = data->device_specific;
real_buffer[4] = data->longlba ? 0x01 : 0;
real_buffer[5] = 0;
real_buffer[6] = data->block_descriptor_length >> 8;
real_buffer[7] = data->block_descriptor_length;
cmd[0] = MODE_SELECT_10;
cmd[7] = len >> 8;
cmd[8] = len;
} else {
if (len > 255 || data->block_descriptor_length > 255 ||
data->longlba)
return -EINVAL;
real_buffer = kmalloc(4 + len, GFP_KERNEL);
if (!real_buffer)
return -ENOMEM;
memcpy(real_buffer + 4, buffer, len);
len += 4;
real_buffer[0] = 0;
real_buffer[1] = data->medium_type;
real_buffer[2] = data->device_specific;
real_buffer[3] = data->block_descriptor_length;
cmd[0] = MODE_SELECT;
cmd[4] = len;
}
ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
sshdr, timeout, retries);
kfree(real_buffer);
return ret;
}
EXPORT_SYMBOL_GPL(scsi_mode_select);
/**
* scsi_mode_sense - issue a mode sense, falling back from 10 to
* six bytes if necessary.
* @sdev: SCSI device to be queried
* @dbd: set if mode sense will allow block descriptors to be returned
* @modepage: mode page being requested
* @buffer: request buffer (may not be smaller than eight bytes)
* @len: length of request buffer.
* @timeout: command timeout
* @retries: number of retries before failing
* @data: returns a structure abstracting the mode header data
* @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)) {
if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
(modepage == 6 || modepage == 8))) {
/* Initio breakage? */
header_length = 0;
data->length = 13;
data->medium_type = 0;
data->device_specific = 0;
data->longlba = 0;
data->block_descriptor_length = 0;
} else if(use_10_for_ms) {
data->length = buffer[0]*256 + buffer[1] + 2;
data->medium_type = buffer[2];
data->device_specific = buffer[3];
data->longlba = buffer[4] & 0x01;
data->block_descriptor_length = buffer[6]*256
+ buffer[7];
} else {
data->length = buffer[0] + 1;
data->medium_type = buffer[1];
data->device_specific = buffer[2];
data->block_descriptor_length = buffer[3];
}
data->header_length = header_length;
}
return result;
}
EXPORT_SYMBOL(scsi_mode_sense);
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_QUIESCE:
case SDEV_OFFLINE:
case SDEV_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_DEL:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_RUNNING:
case SDEV_OFFLINE:
case SDEV_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)
{
struct request_queue *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)
{
struct request_queue *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);
/**
* scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
* @sg: scatter-gather list
* @sg_count: number of segments in sg
* @offset: offset in bytes into sg, on return offset into the mapped area
* @len: bytes to map, on return number of bytes mapped
*
* Returns virtual address of the start of the mapped page
*/
void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
size_t *offset, size_t *len)
{
int i;
size_t sg_len = 0, len_complete = 0;
struct scatterlist *sg;
struct page *page;
WARN_ON(!irqs_disabled());
for_each_sg(sgl, sg, sg_count, i) {
len_complete = sg_len; /* Complete sg-entries */
sg_len += sg->length;
if (sg_len > *offset)
break;
}
if (unlikely(i == sg_count)) {
printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
"elements %d\n",
__FUNCTION__, sg_len, *offset, sg_count);
WARN_ON(1);
return NULL;
}
/* Offset starting from the beginning of first page in this sg-entry */
*offset = *offset - len_complete + sg->offset;
/* Assumption: contiguous pages can be accessed as "page + i" */
page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
*offset &= ~PAGE_MASK;
/* Bytes in this sg-entry from *offset to the end of the page */
sg_len = PAGE_SIZE - *offset;
if (*len > sg_len)
*len = sg_len;
return kmap_atomic(page, KM_BIO_SRC_IRQ);
}
EXPORT_SYMBOL(scsi_kmap_atomic_sg);
/**
* scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously
* mapped with scsi_kmap_atomic_sg
* @virt: virtual address to be unmapped
*/
void scsi_kunmap_atomic_sg(void *virt)
{
kunmap_atomic(virt, KM_BIO_SRC_IRQ);
}
EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
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