linux/drivers/scsi/scsi_lib.c

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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/bitops.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
struct scsi_host_sg_pool {
size_t size;
char *name;
struct kmem_cache *slab;
mempool_t *pool;
};
#define SP(x) { x, "sgpool-" __stringify(x) }
#if (SCSI_MAX_SG_SEGMENTS < 32)
#error SCSI_MAX_SG_SEGMENTS is too small (must be 32 or greater)
#endif
static struct scsi_host_sg_pool scsi_sg_pools[] = {
SP(8),
SP(16),
#if (SCSI_MAX_SG_SEGMENTS > 32)
SP(32),
#if (SCSI_MAX_SG_SEGMENTS > 64)
SP(64),
#if (SCSI_MAX_SG_SEGMENTS > 128)
SP(128),
#if (SCSI_MAX_SG_SEGMENTS > 256)
#error SCSI_MAX_SG_SEGMENTS is too large (256 MAX)
#endif
#endif
#endif
#endif
SP(SCSI_MAX_SG_SEGMENTS)
};
#undef SP
struct kmem_cache *scsi_sdb_cache;
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
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);
/*
* Some devices (USB mass-storage in particular) may transfer
* garbage data together with a residue indicating that the data
* is invalid. Prevent the garbage from being misinterpreted
* and prevent security leaks by zeroing out the excess data.
*/
if (unlikely(req->data_len > 0 && req->data_len <= bufflen))
memset(buffer + (bufflen - req->data_len), 0, req->data_len);
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
* @sgl: 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;
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: DMA_TO_DEVICE, DMA_FROM_DEVICE, or DMA_NONE
* @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
* @privdata: data passed to done()
* @done: callback function when done
* @gfp: memory allocation 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;
scsi_set_resid(cmd, 0);
memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
if (cmd->cmd_len == 0)
cmd->cmd_len = scsi_command_size(cmd->cmnd);
}
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 (scsi_target(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))) {
int flagset;
/*
* 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(shost->host_lock);
spin_lock(sdev->request_queue->queue_lock);
flagset = test_bit(QUEUE_FLAG_REENTER, &q->queue_flags) &&
!test_bit(QUEUE_FLAG_REENTER,
&sdev->request_queue->queue_flags);
if (flagset)
queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue);
__blk_run_queue(sdev->request_queue);
if (flagset)
queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue);
spin_unlock(sdev->request_queue->queue_lock);
[SCSI] limit recursion when flushing shost->starved_list Attached is a patch that should limit a possible recursion that can lead to a stack overflow like follows: Kernel stack overflow. CPU: 3 Not tainted Process zfcperp0.0.d819 (pid: 13897, task: 000000003e0d8cc8, ksp: 000000003499dbb8) Krnl PSW : 0404000180000000 000000000030f8b2 (get_device+0x12/0x48) Krnl GPRS: 00000000135a1980 000000000030f758 000000003ed6c1e8 0000000000000005 0000000000000000 000000000044a780 000000003dbf7000 0000000034e15800 000000003621c048 070000003499c108 000000003499c1a0 000000003ed6c000 0000000040895000 00000000408ab630 000000003499c0a0 000000003499c0a0 Krnl Code: a7 fb ff e8 a7 19 00 00 b9 02 00 22 e3 e0 f0 98 00 24 a7 84 Call Trace: ([<000000004089edc2>] scsi_request_fn+0x13e/0x650 [scsi_mod]) [<00000000002c5ff4>] blk_run_queue+0xd4/0x1a4 [<000000004089ff8c>] scsi_queue_insert+0x22c/0x2a4 [scsi_mod] [<000000004089779a>] scsi_dispatch_cmd+0x8a/0x3d0 [scsi_mod] [<000000004089f1ec>] scsi_request_fn+0x568/0x650 [scsi_mod] ... [<000000004089f1ec>] scsi_request_fn+0x568/0x650 [scsi_mod] [<00000000002c5ff4>] blk_run_queue+0xd4/0x1a4 [<000000004089ff8c>] scsi_queue_insert+0x22c/0x2a4 [scsi_mod] [<000000004089779a>] scsi_dispatch_cmd+0x8a/0x3d0 [scsi_mod] [<000000004089f1ec>] scsi_request_fn+0x568/0x650 [scsi_mod] [<00000000002c5ff4>] blk_run_queue+0xd4/0x1a4 [<000000004089fa9e>] scsi_run_host_queues+0x196/0x230 [scsi_mod] [<00000000409eba28>] zfcp_erp_thread+0x2638/0x3080 [zfcp] [<0000000000107462>] kernel_thread_starter+0x6/0xc [<000000000010745c>] kernel_thread_starter+0x0/0xc <0>Kernel panic - not syncing: Corrupt kernel stack, can't continue. This stack overflow occurred during tests on s390 using zfcp. Recursion depth for this panic was 19. Usually recursion between blk_run_queue and a request_fn is avoided using QUEUE_FLAG_REENTER. But this does not help if the scsi stack tries to flush the starved_list of a scsi_host. Limit recursion depth when flushing the starved_list of a scsi_host. Signed-off-by: Andreas Herrmann <aherrman@de.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-08-09 15:31:16 +00:00
spin_lock(shost->host_lock);
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.
* error - 0 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 error,
int bytes, int requeue)
{
struct request_queue *q = cmd->device->request_queue;
struct request *req = cmd->request;
/*
* If there are blocks left over at the end, set up the command
* to queue the remainder of them.
*/
if (blk_end_request(req, error, bytes)) {
int leftover = (req->hard_nr_sectors << 9);
if (blk_pc_request(req))
leftover = req->data_len;
/* kill remainder if no retrys */
if (error && blk_noretry_request(req))
blk_end_request(req, error, 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;
}
}
/*
* 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 inline unsigned int scsi_sgtable_index(unsigned short nents)
{
unsigned int index;
BUG_ON(nents > SCSI_MAX_SG_SEGMENTS);
if (nents <= 8)
index = 0;
else
index = get_count_order(nents) - 3;
return index;
}
static void scsi_sg_free(struct scatterlist *sgl, unsigned int nents)
{
struct scsi_host_sg_pool *sgp;
sgp = scsi_sg_pools + scsi_sgtable_index(nents);
mempool_free(sgl, sgp->pool);
}
static struct scatterlist *scsi_sg_alloc(unsigned int nents, gfp_t gfp_mask)
{
struct scsi_host_sg_pool *sgp;
sgp = scsi_sg_pools + scsi_sgtable_index(nents);
return mempool_alloc(sgp->pool, gfp_mask);
}
static int scsi_alloc_sgtable(struct scsi_data_buffer *sdb, int nents,
gfp_t gfp_mask)
{
int ret;
BUG_ON(!nents);
ret = __sg_alloc_table(&sdb->table, nents, SCSI_MAX_SG_SEGMENTS,
gfp_mask, scsi_sg_alloc);
if (unlikely(ret))
__sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS,
scsi_sg_free);
return ret;
}
static void scsi_free_sgtable(struct scsi_data_buffer *sdb)
{
__sg_free_table(&sdb->table, SCSI_MAX_SG_SEGMENTS, scsi_sg_free);
}
/*
* 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.
*/
void scsi_release_buffers(struct scsi_cmnd *cmd)
{
if (cmd->sdb.table.nents)
scsi_free_sgtable(&cmd->sdb);
memset(&cmd->sdb, 0, sizeof(cmd->sdb));
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
if (scsi_bidi_cmnd(cmd)) {
struct scsi_data_buffer *bidi_sdb =
cmd->request->next_rq->special;
scsi_free_sgtable(bidi_sdb);
kmem_cache_free(scsi_sdb_cache, bidi_sdb);
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
cmd->request->next_rq->special = NULL;
}
if (scsi_prot_sg_count(cmd))
scsi_free_sgtable(cmd->prot_sdb);
}
EXPORT_SYMBOL(scsi_release_buffers);
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
/*
* Bidi commands Must be complete as a whole, both sides at once.
* If part of the bytes were written and lld returned
* scsi_in()->resid and/or scsi_out()->resid this information will be left
* in req->data_len and req->next_rq->data_len. The upper-layer driver can
* decide what to do with this information.
*/
static void scsi_end_bidi_request(struct scsi_cmnd *cmd)
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
{
struct request *req = cmd->request;
unsigned int dlen = req->data_len;
unsigned int next_dlen = req->next_rq->data_len;
req->data_len = scsi_out(cmd)->resid;
req->next_rq->data_len = scsi_in(cmd)->resid;
/* The req and req->next_rq have not been completed */
BUG_ON(blk_end_bidi_request(req, 0, dlen, next_dlen));
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
scsi_release_buffers(cmd);
/*
* 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);
}
/*
* 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;
struct request_queue *q = cmd->device->request_queue;
struct request *req = cmd->request;
int error = 0;
struct scsi_sense_hdr sshdr;
int sense_valid = 0;
int sense_deferred = 0;
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) {
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;
}
if (!sense_deferred)
error = -EIO;
}
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
if (scsi_bidi_cmnd(cmd)) {
/* will also release_buffers */
scsi_end_bidi_request(cmd);
return;
}
req->data_len = scsi_get_resid(cmd);
}
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
BUG_ON(blk_bidi_rq(req)); /* bidi not support for !blk_pc_request yet */
scsi_release_buffers(cmd);
/*
* 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));
/* 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, error, good_bytes, result == 0) == NULL)
return;
this_count = blk_rq_bytes(req);
/* 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, -EIO, 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);
} else if (sshdr.asc == 0x10) /* DIX */
scsi_end_request(cmd, -EIO, this_count, 0);
else
scsi_end_request(cmd, -EIO, this_count, 1);
return;
case ABORTED_COMMAND:
if (sshdr.asc == 0x10) { /* DIF */
scsi_end_request(cmd, -EIO, this_count, 0);
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, -EIO, 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, -EIO, 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, -EIO, this_count, !result);
}
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
gfp_t gfp_mask)
{
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
int count;
/*
* If sg table allocation fails, requeue request later.
*/
if (unlikely(scsi_alloc_sgtable(sdb, req->nr_phys_segments,
gfp_mask))) {
return BLKPREP_DEFER;
}
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, sdb->table.sgl);
BUG_ON(count > sdb->table.nents);
sdb->table.nents = count;
if (blk_pc_request(req))
sdb->length = req->data_len;
else
sdb->length = req->nr_sectors << 9;
return BLKPREP_OK;
}
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
/*
* 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
*/
int scsi_init_io(struct scsi_cmnd *cmd, gfp_t gfp_mask)
{
int error = scsi_init_sgtable(cmd->request, &cmd->sdb, gfp_mask);
if (error)
goto err_exit;
if (blk_bidi_rq(cmd->request)) {
struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc(
scsi_sdb_cache, GFP_ATOMIC);
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
if (!bidi_sdb) {
error = BLKPREP_DEFER;
goto err_exit;
}
cmd->request->next_rq->special = bidi_sdb;
error = scsi_init_sgtable(cmd->request->next_rq, bidi_sdb,
GFP_ATOMIC);
if (error)
goto err_exit;
}
if (blk_integrity_rq(cmd->request)) {
struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
int ivecs, count;
BUG_ON(prot_sdb == NULL);
ivecs = blk_rq_count_integrity_sg(cmd->request);
if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) {
error = BLKPREP_DEFER;
goto err_exit;
}
count = blk_rq_map_integrity_sg(cmd->request,
prot_sdb->table.sgl);
BUG_ON(unlikely(count > ivecs));
cmd->prot_sdb = prot_sdb;
cmd->prot_sdb->table.nents = count;
}
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
return BLKPREP_OK ;
err_exit:
scsi_release_buffers(cmd);
if (error == BLKPREP_KILL)
scsi_put_command(cmd);
else /* BLKPREP_DEFER */
scsi_unprep_request(cmd->request);
return error;
}
EXPORT_SYMBOL(scsi_init_io);
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;
[SCSI] Let scsi_cmnd->cmnd use request->cmd buffer - struct scsi_cmnd had a 16 bytes command buffer of its own. This is an unnecessary duplication and copy of request's cmd. It is probably left overs from the time that scsi_cmnd could function without a request attached. So clean that up. - Once above is done, few places, apart from scsi-ml, needed adjustments due to changing the data type of scsi_cmnd->cmnd. - Lots of drivers still use MAX_COMMAND_SIZE. So I have left that #define but equate it to BLK_MAX_CDB. The way I see it and is reflected in the patch below is. MAX_COMMAND_SIZE - means: The longest fixed-length (*) SCSI CDB as per the SCSI standard and is not related to the implementation. BLK_MAX_CDB. - The allocated space at the request level - I have audit all ISA drivers and made sure none use ->cmnd in a DMA Operation. Same audit was done by Andi Kleen. (*)fixed-length here means commands that their size can be determined by their opcode and the CDB does not carry a length specifier, (unlike the VARIABLE_LENGTH_CMD(0x7f) command). This is actually not exactly true and the SCSI standard also defines extended commands and vendor specific commands that can be bigger than 16 bytes. The kernel will support these using the same infrastructure used for VARLEN CDB's. So in effect MAX_COMMAND_SIZE means the maximum size command scsi-ml supports without specifying a cmd_len by ULD's Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-04-30 08:19:47 +00:00
cmd->cmnd = req->cmd;
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, GFP_ATOMIC);
if (unlikely(ret))
return ret;
} else {
BUG_ON(req->data_len);
BUG_ON(req->data);
memset(&cmd->sdb, 0, sizeof(cmd->sdb));
req->buffer = NULL;
}
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;
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;
if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
&& sdev->scsi_dh_data->scsi_dh->prep_fn)) {
ret = sdev->scsi_dh_data->scsi_dh->prep_fn(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;
[SCSI] Let scsi_cmnd->cmnd use request->cmd buffer - struct scsi_cmnd had a 16 bytes command buffer of its own. This is an unnecessary duplication and copy of request's cmd. It is probably left overs from the time that scsi_cmnd could function without a request attached. So clean that up. - Once above is done, few places, apart from scsi-ml, needed adjustments due to changing the data type of scsi_cmnd->cmnd. - Lots of drivers still use MAX_COMMAND_SIZE. So I have left that #define but equate it to BLK_MAX_CDB. The way I see it and is reflected in the patch below is. MAX_COMMAND_SIZE - means: The longest fixed-length (*) SCSI CDB as per the SCSI standard and is not related to the implementation. BLK_MAX_CDB. - The allocated space at the request level - I have audit all ISA drivers and made sure none use ->cmnd in a DMA Operation. Same audit was done by Andi Kleen. (*)fixed-length here means commands that their size can be determined by their opcode and the CDB does not carry a length specifier, (unlike the VARIABLE_LENGTH_CMD(0x7f) command). This is actually not exactly true and the SCSI standard also defines extended commands and vendor specific commands that can be bigger than 16 bytes. The kernel will support these using the same infrastructure used for VARLEN CDB's. So in effect MAX_COMMAND_SIZE means the maximum size command scsi-ml supports without specifying a cmd_len by ULD's Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-04-30 08:19:47 +00:00
memset(cmd->cmnd, 0, BLK_MAX_CDB);
return scsi_init_io(cmd, GFP_ATOMIC);
}
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:
case SDEV_CREATED_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);
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 {
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",
__func__);
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);
blk_complete_request(req);
}
static void scsi_softirq_done(struct request *rq)
{
struct scsi_cmnd *cmd = rq->special;
unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
int disposition;
INIT_LIST_HEAD(&cmd->eh_entry);
/*
* Set the serial numbers back to zero
*/
cmd->serial_number = 0;
atomic_inc(&cmd->device->iodone_cnt);
if (cmd->result)
atomic_inc(&cmd->device->ioerr_cnt);
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",
__func__);
blk_dump_rq_flags(req, "foo");
BUG();
}
spin_lock(shost->host_lock);
/*
* We hit this when the driver is using a host wide
* tag map. For device level tag maps the queue_depth check
* in the device ready fn would prevent us from trying
* to allocate a tag. Since the map is a shared host resource
* we add the dev to the starved list so it eventually gets
* a run when a tag is freed.
*/
if (blk_queue_tagged(q) && !blk_rq_tagged(req)) {
if (list_empty(&sdev->starved_entry))
list_add_tail(&sdev->starved_entry,
&shost->starved_list);
goto not_ready;
}
if (!scsi_host_queue_ready(q, shost, sdev))
goto not_ready;
if (scsi_target(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;
struct device *dev = shost->shost_gendev.parent;
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);
blk_queue_max_phys_segments(q, SCSI_MAX_SG_CHAIN_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);
dma_set_seg_boundary(dev, shost->dma_boundary);
blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
/* New queue, no concurrency on queue_flags */
if (!shost->use_clustering)
queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q);
/*
* set a reasonable default alignment on word boundaries: the
* host and device may alter it using
* blk_queue_update_dma_alignment() later.
*/
blk_queue_dma_alignment(q, 0x03);
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);
blk_queue_rq_timed_out(q, scsi_times_out);
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;
}
scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
sizeof(struct scsi_data_buffer),
0, 0, NULL);
if (!scsi_sdb_cache) {
printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
goto cleanup_io_context;
[SCSI] bidirectional command support At the block level bidi request uses req->next_rq pointer for a second bidi_read request. At Scsi-midlayer a second scsi_data_buffer structure is used for the bidi_read part. This bidi scsi_data_buffer is put on request->next_rq->special. Struct scsi_cmnd is not changed. - Define scsi_bidi_cmnd() to return true if it is a bidi request and a second sgtable was allocated. - Define scsi_in()/scsi_out() to return the in or out scsi_data_buffer from this command This API is to isolate users from the mechanics of bidi. - Define scsi_end_bidi_request() to do what scsi_end_request() does but for a bidi request. This is necessary because bidi commands are a bit tricky here. (See comments in body) - scsi_release_buffers() will also release the bidi_read scsi_data_buffer - scsi_io_completion() on bidi commands will now call scsi_end_bidi_request() and return. - The previous work done in scsi_init_io() is now done in a new scsi_init_sgtable() (which is 99% identical to old scsi_init_io()) The new scsi_init_io() will call the above twice if needed also for the bidi_read command. Only at this point is a command bidi. - In scsi_error.c at scsi_eh_prep/restore_cmnd() make sure bidi-lld is not confused by a get-sense command that looks like bidi. This is done by puting NULL at request->next_rq, and restoring. [jejb: update to sg_table and resolve conflicts also update to blk-end-request and resolve conflicts] Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2007-12-13 11:50:53 +00:00
}
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);
goto cleanup_sdb;
}
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);
goto cleanup_sdb;
}
}
return 0;
cleanup_sdb:
for (i = 0; i < SG_MEMPOOL_NR; i++) {
struct scsi_host_sg_pool *sgp = scsi_sg_pools + i;
if (sgp->pool)
mempool_destroy(sgp->pool);
if (sgp->slab)
kmem_cache_destroy(sgp->slab);
}
kmem_cache_destroy(scsi_sdb_cache);
cleanup_io_context:
kmem_cache_destroy(scsi_io_context_cache);
return -ENOMEM;
}
void scsi_exit_queue(void)
{
int i;
kmem_cache_destroy(scsi_io_context_cache);
kmem_cache_destroy(scsi_sdb_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
* @sshdr: place to put sense data (or NULL if no sense to be collected).
* must be SCSI_SENSE_BUFFERSIZE big.
*
* Returns zero if successful; negative error number or scsi
* status on error
*
*/
int
scsi_mode_select(struct scsi_device *sdev, int pf, int sp, 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
* @sshdr: 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);
/**
* scsi_test_unit_ready - test if unit is ready
* @sdev: scsi device to change the state of.
* @timeout: command timeout
* @retries: number of retries before failing
* @sshdr_external: Optional pointer to struct scsi_sense_hdr for
* returning sense. Make sure that this is cleared before passing
* in.
*
* Returns zero if unsuccessful or an error if TUR failed. For
* removable media, a return of NOT_READY or UNIT_ATTENTION is
* translated to success, with the ->changed flag updated.
**/
int
scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
struct scsi_sense_hdr *sshdr_external)
{
char cmd[] = {
TEST_UNIT_READY, 0, 0, 0, 0, 0,
};
struct scsi_sense_hdr *sshdr;
int result;
if (!sshdr_external)
sshdr = kzalloc(sizeof(*sshdr), GFP_KERNEL);
else
sshdr = sshdr_external;
/* try to eat the UNIT_ATTENTION if there are enough retries */
do {
result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
timeout, retries);
} while ((driver_byte(result) & DRIVER_SENSE) &&
sshdr && sshdr->sense_key == UNIT_ATTENTION &&
--retries);
if (!sshdr)
/* could not allocate sense buffer, so can't process it */
return result;
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;
}
}
if (!sshdr_external)
kfree(sshdr);
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:
switch (oldstate) {
case SDEV_CREATED_BLOCK:
break;
default:
goto illegal;
}
break;
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_RUNNING:
case SDEV_CREATED_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_CREATED_BLOCK:
switch (oldstate) {
case SDEV_CREATED:
break;
default:
goto illegal;
}
break;
case SDEV_CANCEL:
switch (oldstate) {
case SDEV_CREATED:
case SDEV_RUNNING:
case SDEV_QUIESCE:
case SDEV_OFFLINE:
case SDEV_BLOCK:
break;
default:
goto illegal;
}
break;
case SDEV_DEL:
switch (oldstate) {
[SCSI] scsi: Device scanning oops for offlined devices (resend) If a device gets offlined as a result of the Inquiry sent during scanning, the following oops can occur. After the disk gets put into the SDEV_OFFLINE state, the error handler sends back the failed inquiry, which wakes the thread doing the scan. This starts a race between the scanning thread freeing the scsi device and the error handler calling scsi_run_host_queues to restart the host. Since the disk is in the SDEV_OFFLINE state, scsi_device_get will still work, which results in __scsi_iterate_devices getting a reference to the scsi disk when it shouldn't. The following execution thread causes the oops: CPU 0 (scan) CPU 1 (eh) --------------------------------------------------------- scsi_probe_and_add_lun .... scsi_eh_offline_sdevs scsi_eh_flush_done_q scsi_destroy_sdev scsi_device_dev_release scsi_restart_operations scsi_run_host_queues __scsi_iterate_devices get_device scsi_device_dev_release_usercontext scsi_run_queue <---OOPS---> The patch fixes this by changing the state of the sdev to SDEV_DEL before doing the final put_device, which should prevent the race from occurring. Original oops follows: Badness in kref_get at lib/kref.c:32 Call Trace: [C00000002F4476D0] [C00000000000EE20] .show_stack+0x68/0x1b0 (unreliable) [C00000002F447770] [C00000000037515C] .program_check_exception+0x1cc/0x5a8 [C00000002F447840] [C00000000000446C] program_check_common+0xec/0x100 Exception: 700 at .kref_get+0x10/0x28 LR = .kobject_get+0x20/0x3c [C00000002F447B30] [C00000002F447BC0] 0xc00000002f447bc0 (unreliable) [C00000002F447BB0] [C000000000254BDC] .get_device+0x20/0x3c [C00000002F447C30] [D000000000063188] .scsi_device_get+0x34/0xdc [scsi_mod] [C00000002F447CC0] [D0000000000633EC] .__scsi_iterate_devices+0x50/0xbc [scsi_mod] [C00000002F447D60] [D00000000006A910] .scsi_run_host_queues+0x34/0x5c [scsi_mod] [C00000002F447DF0] [D000000000069054] .scsi_error_handler+0xdb4/0xe44 [scsi_mod] [C00000002F447EE0] [C00000000007B4E0] .kthread+0x128/0x178 [C00000002F447F90] [C000000000025E84] .kernel_thread+0x4c/0x68 Unable to handle kernel paging request for <7>PCI: Enabling device: (0002:41:01.1), cmd 143 data at address 0x000001b8 Faulting instruction address: 0xd0000000000698e4 sym1: <1010-66> rev 0x1 at pci 0002:41:01.1 irq 216 sym1: No NVRAM, ID 7, Fast-80, LVD, parity checking sym1: SCSI BUS has been reset. scsi2 : sym-2.2.2 cpu 0x0: Vector: 300 (Data Access) at [c00000002f447a30] pc: d0000000000698e4: .scsi_run_queue+0x2c/0x218 [scsi_mod] lr: d00000000006a904: .scsi_run_host_queues+0x28/0x5c [scsi_mod] sp: c00000002f447cb0 msr: 9000000000009032 dar: 1b8 dsisr: 40000000 current = 0xc0000000045fecd0 paca = 0xc00000000048ee80 pid = 1123, comm = scsi_eh_1 enter ? for help [c00000002f447d60] d00000000006a904 .scsi_run_host_queues+0x28/0x5c [scsi_mod] [c00000002f447df0] d000000000069054 .scsi_error_handler+0xdb4/0xe44 [scsi_mod] [c00000002f447ee0] c00000000007b4e0 .kthread+0x128/0x178 [c00000002f447f90] c000000000025e84 .kernel_thread+0x4c/0x68 Signed-off-by: Brian King <brking@us.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-06-27 16:10:43 +00:00
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);
/**
* sdev_evt_emit - emit a single SCSI device uevent
* @sdev: associated SCSI device
* @evt: event to emit
*
* Send a single uevent (scsi_event) to the associated scsi_device.
*/
static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
{
int idx = 0;
char *envp[3];
switch (evt->evt_type) {
case SDEV_EVT_MEDIA_CHANGE:
envp[idx++] = "SDEV_MEDIA_CHANGE=1";
break;
default:
/* do nothing */
break;
}
envp[idx++] = NULL;
kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
}
/**
* sdev_evt_thread - send a uevent for each scsi event
* @work: work struct for scsi_device
*
* Dispatch queued events to their associated scsi_device kobjects
* as uevents.
*/
void scsi_evt_thread(struct work_struct *work)
{
struct scsi_device *sdev;
LIST_HEAD(event_list);
sdev = container_of(work, struct scsi_device, event_work);
while (1) {
struct scsi_event *evt;
struct list_head *this, *tmp;
unsigned long flags;
spin_lock_irqsave(&sdev->list_lock, flags);
list_splice_init(&sdev->event_list, &event_list);
spin_unlock_irqrestore(&sdev->list_lock, flags);
if (list_empty(&event_list))
break;
list_for_each_safe(this, tmp, &event_list) {
evt = list_entry(this, struct scsi_event, node);
list_del(&evt->node);
scsi_evt_emit(sdev, evt);
kfree(evt);
}
}
}
/**
* sdev_evt_send - send asserted event to uevent thread
* @sdev: scsi_device event occurred on
* @evt: event to send
*
* Assert scsi device event asynchronously.
*/
void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
{
unsigned long flags;
#if 0
/* FIXME: currently this check eliminates all media change events
* for polled devices. Need to update to discriminate between AN
* and polled events */
if (!test_bit(evt->evt_type, sdev->supported_events)) {
kfree(evt);
return;
}
#endif
spin_lock_irqsave(&sdev->list_lock, flags);
list_add_tail(&evt->node, &sdev->event_list);
schedule_work(&sdev->event_work);
spin_unlock_irqrestore(&sdev->list_lock, flags);
}
EXPORT_SYMBOL_GPL(sdev_evt_send);
/**
* sdev_evt_alloc - allocate a new scsi event
* @evt_type: type of event to allocate
* @gfpflags: GFP flags for allocation
*
* Allocates and returns a new scsi_event.
*/
struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
gfp_t gfpflags)
{
struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
if (!evt)
return NULL;
evt->evt_type = evt_type;
INIT_LIST_HEAD(&evt->node);
/* evt_type-specific initialization, if any */
switch (evt_type) {
case SDEV_EVT_MEDIA_CHANGE:
default:
/* do nothing */
break;
}
return evt;
}
EXPORT_SYMBOL_GPL(sdev_evt_alloc);
/**
* sdev_evt_send_simple - send asserted event to uevent thread
* @sdev: scsi_device event occurred on
* @evt_type: type of event to send
* @gfpflags: GFP flags for allocation
*
* Assert scsi device event asynchronously, given an event type.
*/
void sdev_evt_send_simple(struct scsi_device *sdev,
enum scsi_device_event evt_type, gfp_t gfpflags)
{
struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
if (!evt) {
sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
evt_type);
return;
}
sdev_evt_send(sdev, evt);
}
EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
/**
* scsi_device_quiesce - Block 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) {
err = scsi_device_set_state(sdev, SDEV_CREATED_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) {
err = scsi_device_set_state(sdev, SDEV_CREATED);
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] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
/**
* scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
* @sgl: scatter-gather list
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
* @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,
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
size_t *offset, size_t *len)
{
int i;
size_t sg_len = 0, len_complete = 0;
struct scatterlist *sg;
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
struct page *page;
WARN_ON(!irqs_disabled());
for_each_sg(sgl, sg, sg_count, i) {
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
len_complete = sg_len; /* Complete sg-entries */
sg_len += sg->length;
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
if (sg_len > *offset)
break;
}
if (unlikely(i == sg_count)) {
printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
"elements %d\n",
__func__, sg_len, *offset, sg_count);
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
WARN_ON(1);
return NULL;
}
/* Offset starting from the beginning of first page in this sg-entry */
*offset = *offset - len_complete + sg->offset;
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
/* Assumption: contiguous pages can be accessed as "page + i" */
page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
*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
[SCSI] dc395x: dynamically map scatter-gather for PIO The current dc395x driver uses PIO to transfer up to 4 bytes which do not get transferred by DMA (under unclear circumstances). For this the driver uses page_address() which is broken on highmem. Apart from this the actual calculation of the virtual address is wrong (even without highmem). So, e.g., for reading it reads bytes from the driver to a wrong address and returns wrong data, I guess, for writing it would just output random data to the device. The proper fix, as suggested by many, is to dynamically map data using kmap_atomic(page, KM_BIO_SRC_IRQ) / kunmap_atomic(virt). The reason why it has not been done until now, although I've done some preliminary patches more than a year ago was that nobody interested in fixing this problem was able to reliably reproduce it. Now it changed - with the help from Sebastian Frei (CC'ed) I was able to trigger the PIO path. Thus, I was also able to test and debug it. There are 4 cases when PIO is used in dc395x - data-in / -out with and without scatter-gather. I was able to reproduce and test only data-in with and without SG. So, the data-out path is still untested, but it is also somewhat simpler than the data-in. Fredrik Roubert (also CC'ed) also had PIO triggering on his system, and in his case it was data-out without SG. It would be great if he could test the attached patch on his system, but even if he cannot, I would still request to apply the patch and just wait if anybody cries... Implementation: I put 2 new functions in scsi_lib.c and their declarations in scsi_cmnd.h. I exported them without _GPL, although, I don't feel strongly about that - not many drivers are likely to use them. But there is at least one more - I want to use them in tmscsim.c. Whether these are the right files for the functions and their declarations - not sure either. Actually, they are not scsi-specific, so, might go somewhere around other scattergather magic? They are not platform specific either, and most SG functions are defined under arch/*/... As these issues were discussed previously there were some more routines suggested to manipulate scattergather buffers, I think, some of them were needed around crypto code... So, might be a common place reasonable, like lib/scattergather.c? I am open here. Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2006-04-02 19:57:43 +00:00
* @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);