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scsi_lib.c
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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/export.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;
/*
* When to reinvoke queueing after a resource shortage. It's 3 msecs to
* not change behaviour from the previous unplug mechanism, experimentation
* may prove this needs changing.
*/
#define SCSI_QUEUE_DELAY 3
/*
* 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;
blk_unprep_request(req);
req->special = NULL;
scsi_put_command(cmd);
}
/**
* __scsi_queue_insert - private queue insertion
* @cmd: The SCSI command being requeued
* @reason: The reason for the requeue
* @unbusy: Whether the queue should be unbusied
*
* This is a private queue insertion. The public interface
* scsi_queue_insert() always assumes the queue should be unbusied
* because it's always called before the completion. This function is
* for a requeue after completion, which should only occur in this
* file.
*/
static int __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, int unbusy)
{
struct Scsi_Host *host = cmd->device->host;
struct scsi_device *device = cmd->device;
struct scsi_target *starget = scsi_target(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.
*/
switch (reason) {
case SCSI_MLQUEUE_HOST_BUSY:
host->host_blocked = host->max_host_blocked;
break;
case SCSI_MLQUEUE_DEVICE_BUSY:
case SCSI_MLQUEUE_EH_RETRY:
device->device_blocked = device->max_device_blocked;
break;
case SCSI_MLQUEUE_TARGET_BUSY:
starget->target_blocked = starget->max_target_blocked;
break;
}
/*
* Decrement the counters, since these commands are no longer
* active on the host/device.
*/
if (unbusy)
scsi_device_unbusy(device);
/*
* Requeue this command. It will go before all other commands
* that are already in the queue.
*/
spin_lock_irqsave(q->queue_lock, flags);
blk_requeue_request(q, cmd->request);
spin_unlock_irqrestore(q->queue_lock, flags);
kblockd_schedule_work(q, &device->requeue_work);
return 0;
}
/*
* Function: scsi_queue_insert()
*
* Purpose: Insert a command in the midlevel queue.
*
* Arguments: cmd - command that we are adding to queue.
* reason - why we are inserting command to queue.
*
* Lock status: Assumed that lock is not held upon entry.
*
* Returns: Nothing.
*
* Notes: We do this for one of two cases. Either the host is busy
* and it cannot accept any more commands for the time being,
* or the device returned QUEUE_FULL and can accept no more
* commands.
* Notes: This could be called either from an interrupt context or a
* normal process context.
*/
int scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
{
return __scsi_queue_insert(cmd, reason, 1);
}
/**
* 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;
* @resid: optional residual length
*
* 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,
int *resid)
{
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 (!req)
return ret;
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->resid_len > 0 && req->resid_len <= bufflen))
memset(buffer + (bufflen - req->resid_len), 0, req->resid_len);
if (resid)
*resid = req->resid_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,
int *resid)
{
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, resid);
if (sshdr)
scsi_normalize_sense(sense, SCSI_SENSE_BUFFERSIZE, sshdr);
kfree(sense);
return result;
}
EXPORT_SYMBOL(scsi_execute_req);
/*
* 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;
struct scsi_target *starget = scsi_target(sdev);
unsigned long flags;
spin_lock_irqsave(shost->host_lock, flags);
shost->host_busy--;
starget->target_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);
}
static inline int scsi_device_is_busy(struct scsi_device *sdev)
{
if (sdev->device_busy >= sdev->queue_depth || sdev->device_blocked)
return 1;
return 0;
}
static inline int scsi_target_is_busy(struct scsi_target *starget)
{
return ((starget->can_queue > 0 &&
starget->target_busy >= starget->can_queue) ||
starget->target_blocked);
}
static inline int scsi_host_is_busy(struct Scsi_Host *shost)
{
if ((shost->can_queue > 0 && shost->host_busy >= shost->can_queue) ||
shost->host_blocked || shost->host_self_blocked)
return 1;
return 0;
}
/*
* 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;
LIST_HEAD(starved_list);
unsigned long flags;
/* if the device is dead, sdev will be NULL, so no queue to run */
if (!sdev)
return;
shost = sdev->host;
if (scsi_target(sdev)->single_lun)
scsi_single_lun_run(sdev);
spin_lock_irqsave(shost->host_lock, flags);
list_splice_init(&shost->starved_list, &starved_list);
while (!list_empty(&starved_list)) {
/*
* 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.
*/
if (scsi_host_is_busy(shost))
break;
sdev = list_entry(starved_list.next,
struct scsi_device, starved_entry);
list_del_init(&sdev->starved_entry);
if (scsi_target_is_busy(scsi_target(sdev))) {
list_move_tail(&sdev->starved_entry,
&shost->starved_list);
continue;
}
spin_unlock(shost->host_lock);
spin_lock(sdev->request_queue->queue_lock);
__blk_run_queue(sdev->request_queue);
spin_unlock(sdev->request_queue->queue_lock);
spin_lock(shost->host_lock);
}
/* put any unprocessed entries back */
list_splice(&starved_list, &shost->starved_list);
spin_unlock_irqrestore(shost->host_lock, flags);
blk_run_queue(q);
}
void scsi_requeue_run_queue(struct work_struct *work)
{
struct scsi_device *sdev;
struct request_queue *q;
sdev = container_of(work, struct scsi_device, requeue_work);
q = sdev->request_queue;
scsi_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;
spin_lock_irqsave(q->queue_lock, flags);
scsi_unprep_request(req);
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);
}
static void __scsi_release_buffers(struct scsi_cmnd *, int);
/*
* 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)) {
/* kill remainder if no retrys */
if (error && scsi_noretry_cmd(cmd))
blk_end_request_all(req, error);
else {
if (requeue) {
/*
* Bleah. Leftovers again. Stick the
* leftovers in the front of the
* queue, and goose the queue again.
*/
scsi_release_buffers(cmd);
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_release_buffers(cmd, 0);
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);
}
static void __scsi_release_buffers(struct scsi_cmnd *cmd, int do_bidi_check)
{
if (cmd->sdb.table.nents)
scsi_free_sgtable(&cmd->sdb);
memset(&cmd->sdb, 0, sizeof(cmd->sdb));
if (do_bidi_check && 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);
cmd->request->next_rq->special = NULL;
}
if (scsi_prot_sg_count(cmd))
scsi_free_sgtable(cmd->prot_sdb);
}
/*
* 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)
{
__scsi_release_buffers(cmd, 1);
}
EXPORT_SYMBOL(scsi_release_buffers);
static int __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result)
{
int error = 0;
switch(host_byte(result)) {
case DID_TRANSPORT_FAILFAST:
error = -ENOLINK;
break;
case DID_TARGET_FAILURE:
set_host_byte(cmd, DID_OK);
error = -EREMOTEIO;
break;
case DID_NEXUS_FAILURE:
set_host_byte(cmd, DID_OK);
error = -EBADE;
break;
default:
error = -EIO;
break;
}
return error;
}
/*
* 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 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 we have to
* figure out what to do next:
*
* a) We can call scsi_requeue_command(). The request
* will be unprepared and put back on the queue. Then
* a new command will be created for it. This should
* be used if we made forward progress, or if we want
* to switch from READ(10) to READ(6) for example.
*
* b) We can call scsi_queue_insert(). The request will
* be put back on the queue and retried using the same
* command as before, possibly after a delay.
*
* c) We can call blk_end_request() with -EIO to fail
* the remainder of the request.
*/
void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
{
int result = cmd->result;
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;
enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
ACTION_DELAYED_RETRY} action;
char *description = NULL;
if (result) {
sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
if (sense_valid)
sense_deferred = scsi_sense_is_deferred(&sshdr);
}
if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* 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 = __scsi_error_from_host_byte(cmd, result);
}
req->resid_len = scsi_get_resid(cmd);
if (scsi_bidi_cmnd(cmd)) {
/*
* Bidi commands Must be complete as a whole,
* both sides at once.
*/
req->next_rq->resid_len = scsi_in(cmd)->resid;
scsi_release_buffers(cmd);
blk_end_request_all(req, 0);
scsi_next_command(cmd);
return;
}
}
/* no bidi support for !REQ_TYPE_BLOCK_PC yet */
BUG_ON(blk_bidi_rq(req));
/*
* Next deal with any sectors which we were able to correctly
* handle.
*/
SCSI_LOG_HLCOMPLETE(1, printk("%u sectors total, "
"%d bytes done.\n",
blk_rq_sectors(req), good_bytes));
/*
* Recovered errors need reporting, but they're always treated
* as success, so fiddle the result code here. For BLOCK_PC
* we already took a copy of the original into rq->errors which
* is what gets returned to the user
*/
if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
/* if ATA PASS-THROUGH INFORMATION AVAILABLE skip
* print since caller wants ATA registers. Only occurs on
* SCSI ATA PASS_THROUGH commands when CK_COND=1
*/
if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
;
else if (!(req->cmd_flags & REQ_QUIET))
scsi_print_sense("", cmd);
result = 0;
/* BLOCK_PC may have set error */
error = 0;
}
/*
* A number of bytes were successfully read. If there
* are leftovers and there is some kind of error
* (result != 0), retry the rest.
*/
if (scsi_end_request(cmd, error, good_bytes, result == 0) == NULL)
return;
error = __scsi_error_from_host_byte(cmd, result);
if (host_byte(result) == DID_RESET) {
/* Third party bus reset or reset for error recovery
* reasons. Just retry the command and see what
* happens.
*/
action = ACTION_RETRY;
} else 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;
description = "Media Changed";
action = ACTION_FAIL;
} else {
/* Must have been a power glitch, or a
* bus reset. Could not have been a
* media change, so we just retry the
* command and see what happens.
*/
action = ACTION_RETRY;
}
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)) {
/* This will issue a new 6-byte command. */
cmd->device->use_10_for_rw = 0;
action = ACTION_REPREP;
} else if (sshdr.asc == 0x10) /* DIX */ {
description = "Host Data Integrity Failure";
action = ACTION_FAIL;
error = -EILSEQ;
/* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
} else if ((sshdr.asc == 0x20 || sshdr.asc == 0x24) &&
(cmd->cmnd[0] == UNMAP ||
cmd->cmnd[0] == WRITE_SAME_16 ||
cmd->cmnd[0] == WRITE_SAME)) {
description = "Discard failure";
action = ACTION_FAIL;
error = -EREMOTEIO;
} else
action = ACTION_FAIL;
break;
case ABORTED_COMMAND:
action = ACTION_FAIL;
if (sshdr.asc == 0x10) { /* DIF */
description = "Target Data Integrity Failure";
error = -EILSEQ;
}
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 */
case 0x14: /* space allocation in progress */
action = ACTION_DELAYED_RETRY;
break;
default:
description = "Device not ready";
action = ACTION_FAIL;
break;
}
} else {
description = "Device not ready";
action = ACTION_FAIL;
}
break;
case VOLUME_OVERFLOW:
/* See SSC3rXX or current. */
action = ACTION_FAIL;
break;
default:
description = "Unhandled sense code";
action = ACTION_FAIL;
break;
}
} else {
description = "Unhandled error code";
action = ACTION_FAIL;
}
switch (action) {
case ACTION_FAIL:
/* Give up and fail the remainder of the request */
scsi_release_buffers(cmd);
if (!(req->cmd_flags & REQ_QUIET)) {
if (description)
scmd_printk(KERN_INFO, cmd, "%s\n",
description);
scsi_print_result(cmd);
if (driver_byte(result) & DRIVER_SENSE)
scsi_print_sense("", cmd);
scsi_print_command(cmd);
}
if (blk_end_request_err(req, error))
scsi_requeue_command(q, cmd);
else
scsi_next_command(cmd);
break;
case ACTION_REPREP:
/* Unprep the request and put it back at the head of the queue.
* A new command will be prepared and issued.
*/
scsi_release_buffers(cmd);
scsi_requeue_command(q, cmd);
break;
case ACTION_RETRY:
/* Retry the same command immediately */
__scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, 0);
break;
case ACTION_DELAYED_RETRY:
/* Retry the same command after a delay */
__scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, 0);
break;
}
}
static int scsi_init_sgtable(struct request *req, struct scsi_data_buffer *sdb,
gfp_t gfp_mask)
{
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;
sdb->length = blk_rq_bytes(req);
return BLKPREP_OK;
}
/*
* Function: scsi_init_io()
*
* Purpose: SCSI I/O initialize function.
*