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Diffstat (limited to 'drivers/scsi/scsi_lib.c')
| -rw-r--r-- | drivers/scsi/scsi_lib.c | 2589 |
1 files changed, 2589 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c new file mode 100644 index 00000000..7ca46131 --- /dev/null +++ b/drivers/scsi/scsi_lib.c @@ -0,0 +1,2589 @@ +/* + * 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. + * + * 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) +{ + struct request *rq = cmd->request; + + int error = scsi_init_sgtable(rq, &cmd->sdb, gfp_mask); + if (error) + goto err_exit; + + if (blk_bidi_rq(rq)) { + struct scsi_data_buffer *bidi_sdb = kmem_cache_zalloc( + scsi_sdb_cache, GFP_ATOMIC); + if (!bidi_sdb) { + error = BLKPREP_DEFER; + goto err_exit; + } + + rq->next_rq->special = bidi_sdb; + error = scsi_init_sgtable(rq->next_rq, bidi_sdb, GFP_ATOMIC); + if (error) + goto err_exit; + } + + if (blk_integrity_rq(rq)) { + struct scsi_data_buffer *prot_sdb = cmd->prot_sdb; + int ivecs, count; + + BUG_ON(prot_sdb == NULL); + ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio); + + if (scsi_alloc_sgtable(prot_sdb, ivecs, gfp_mask)) { + error = BLKPREP_DEFER; + goto err_exit; + } + + count = blk_rq_map_integrity_sg(rq->q, rq->bio, + prot_sdb->table.sgl); + BUG_ON(unlikely(count > ivecs)); + BUG_ON(unlikely(count > queue_max_integrity_segments(rq->q))); + + cmd->prot_sdb = prot_sdb; + cmd->prot_sdb->table.nents = count; + } + + return BLKPREP_OK ; + +err_exit: + scsi_release_buffers(cmd); + cmd->request->special = NULL; + scsi_put_command(cmd); + 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; + + cmd->cmnd = req->cmd; + cmd->prot_op = SCSI_PROT_NORMAL; + + 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(blk_rq_bytes(req)); + + memset(&cmd->sdb, 0, sizeof(cmd->sdb)); + req->buffer = NULL; + } + + cmd->cmd_len = req->cmd_len; + if (!blk_rq_bytes(req)) + 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 = blk_rq_bytes(req); + 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; + + 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(sdev==NULL){ + ret = BLKPREP_KILL; + return ret; + } + /* + * 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 blk_peek_request() returns NULL, but the + * queue must be restarted, so we schedule a callback to happen + * shortly. + */ + if (sdev->device_busy == 0) + blk_delay_queue(q, SCSI_QUEUE_DELAY); + 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); +} +EXPORT_SYMBOL(scsi_prep_fn); + +/* + * 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 == 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_delay_queue(q, SCSI_QUEUE_DELAY); + return 0; + } + } + if (scsi_device_is_busy(sdev)) + return 0; + + return 1; +} + + +/* + * scsi_target_queue_ready: checks if there we can send commands to target + * @sdev: scsi device on starget to check. + * + * Called with the host lock held. + */ +static inline int scsi_target_queue_ready(struct Scsi_Host *shost, + struct scsi_device *sdev) +{ + struct scsi_target *starget = scsi_target(sdev); + + if (starget->single_lun) { + if (starget->starget_sdev_user && + starget->starget_sdev_user != sdev) + return 0; + starget->starget_sdev_user = sdev; + } + + if (starget->target_busy == 0 && starget->target_blocked) { + /* + * unblock after target_blocked iterates to zero + */ + if (--starget->target_blocked == 0) { + SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget, + "unblocking target at zero depth\n")); + } else + return 0; + } + + if (scsi_target_is_busy(starget)) { + list_move_tail(&sdev->starved_entry, &shost->starved_list); + 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 (scsi_host_is_busy(shost)) { + 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; +} + +/* + * Busy state exporting function for request stacking drivers. + * + * For efficiency, no lock is taken to check the busy state of + * shost/starget/sdev, since the returned value is not guaranteed and + * may be changed after request stacking drivers call the function, + * regardless of taking lock or not. + * + * When scsi can't dispatch I/Os anymore and needs to kill I/Os + * (e.g. !sdev), scsi needs to return 'not busy'. + * Otherwise, request stacking drivers may hold requests forever. + */ +static int scsi_lld_busy(struct request_queue *q) +{ + struct scsi_device *sdev = q->queuedata; + struct Scsi_Host *shost; + + if (!sdev) + return 0; + + shost = sdev->host; + + /* + * Ignore host/starget busy state. + * Since block layer does not have a concept of fairness across + * multiple queues, congestion of host/starget needs to be handled + * in SCSI layer. + */ + if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev)) + return 1; + + return 0; +} + +/* + * 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; + struct scsi_target *starget; + struct Scsi_Host *shost; + + blk_start_request(req); + + scmd_printk(KERN_INFO, cmd, "killing request\n"); + + sdev = cmd->device; + starget = scsi_target(sdev); + shost = sdev->host; + 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++; + starget->target_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); + + 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) { + while ((req = blk_peek_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; + for (;;) { + 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 = blk_peek_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))) + blk_start_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_target_queue_ready(shost, sdev)) + goto not_ready; + + if (!scsi_host_queue_ready(q, shost, sdev)) + goto not_ready; + + scsi_target(sdev)->target_busy++; + 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) + goto out_delay; + } + + 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--; +out_delay: + if (sdev->device_busy == 0) + blk_delay_queue(q, SCSI_QUEUE_DELAY); +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->dma_dev; + + q = blk_init_queue(request_fn, NULL); + if (!q) + return NULL; + + /* + * this limit is imposed by hardware restrictions + */ + blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize, + SCSI_MAX_SG_CHAIN_SEGMENTS)); + + if (scsi_host_prot_dma(shost)) { + shost->sg_prot_tablesize = + min_not_zero(shost->sg_prot_tablesize, + (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS); + BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize); + blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize); + } + + blk_queue_max_hw_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)); + + if (!shost->use_clustering) + q->limits.cluster = 0; + + /* + * 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); + blk_queue_lld_busy(q, scsi_lld_busy); + return q; +} + +void scsi_free_queue(struct request_queue *q) +{ + unsigned long flags; + + WARN_ON(q->queuedata); + + /* cause scsi_request_fn() to kill all non-finished requests */ + spin_lock_irqsave(q->queue_lock, flags); + q->request_fn(q); + spin_unlock_irqrestore(q->queue_lock, flags); + + 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_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"); + return -ENOMEM; + } + + for (i = 0; i < SG_MEMPOOL_NR; i++) { + struct scsi_host_sg_pool *sgp = scsi_sg_pools + i; + int size = sgp->size * sizeof(struct scatterlist); + + sgp->slab = kmem_cache_create(sgp->name, size, 0, + SLAB_HWCACHE_ALIGN, NULL); + if (!sgp->slab) { + printk(KERN_ERR "SCSI: can't init sg slab %s\n", + sgp->name); + 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); + + return -ENOMEM; +} + +void scsi_exit_queue(void) +{ + int i; + + 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, NULL); + 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, NULL); + + /* 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, UNIT_ATTENTION sets ->changed flag. + **/ +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, NULL); + if (sdev->removable && scsi_sense_valid(sshdr) && + sshdr->sense_key == UNIT_ATTENTION) + sdev->changed = 1; + } while (scsi_sense_valid(sshdr) && + sshdr->sense_key == UNIT_ATTENTION && --retries); + + 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) { + 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; + unsigned long flags; + + /* + * Try to transition the scsi device to SDEV_RUNNING + * and goose the device queue if successful. + */ + if (sdev->sdev_state == SDEV_BLOCK) + sdev->sdev_state = SDEV_RUNNING; + else if (sdev->sdev_state == SDEV_CREATED_BLOCK) + sdev->sdev_state = SDEV_CREATED; + else if (sdev->sdev_state != SDEV_CANCEL && + sdev->sdev_state != SDEV_OFFLINE) + return -EINVAL; + + spin_lock_irqsave(q->queue_lock, flags); + blk_start_queue(q); + spin_unlock_irqrestore(q->queue_lock, flags); + + return 0; +} +EXPORT_SYMBOL_GPL(scsi_internal_device_unblock); + +static void +device_block(struct scsi_device *sdev, void *data) +{ + scsi_internal_device_block(sdev); +} + +static int +target_block(struct device *dev, void *data) +{ + if (scsi_is_target_device(dev)) + starget_for_each_device(to_scsi_target(dev), NULL, + device_block); + return 0; +} + +void +scsi_target_block(struct device *dev) +{ + if (scsi_is_target_device(dev)) + starget_for_each_device(to_scsi_target(dev), NULL, + device_block); + else + device_for_each_child(dev, NULL, target_block); +} +EXPORT_SYMBOL_GPL(scsi_target_block); + +static void +device_unblock(struct scsi_device *sdev, void *data) +{ + scsi_internal_device_unblock(sdev); +} + +static int +target_unblock(struct device *dev, void *data) +{ + if (scsi_is_target_device(dev)) + starget_for_each_device(to_scsi_target(dev), NULL, + device_unblock); + return 0; +} + +void +scsi_target_unblock(struct device *dev) +{ + if (scsi_is_target_device(dev)) + starget_for_each_device(to_scsi_target(dev), NULL, + device_unblock); + else + device_for_each_child(dev, NULL, target_unblock); +} +EXPORT_SYMBOL_GPL(scsi_target_unblock); + +/** + * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt + * @sgl: scatter-gather list + * @sg_count: number of segments in sg + * @offset: offset in bytes into sg, on return offset into the mapped area + * @len: bytes to map, on return number of bytes mapped + * + * Returns virtual address of the start of the mapped page + */ +void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count, + size_t *offset, size_t *len) +{ + int i; + size_t sg_len = 0, len_complete = 0; + struct scatterlist *sg; + struct page *page; + + WARN_ON(!irqs_disabled()); + + for_each_sg(sgl, sg, sg_count, i) { + len_complete = sg_len; /* Complete sg-entries */ + sg_len += sg->length; + if (sg_len > *offset) + break; + } + + if (unlikely(i == sg_count)) { + printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, " + "elements %d\n", + __func__, sg_len, *offset, sg_count); + WARN_ON(1); + return NULL; + } + + /* Offset starting from the beginning of first page in this sg-entry */ + *offset = *offset - len_complete + sg->offset; + + /* Assumption: contiguous pages can be accessed as "page + i" */ + page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT)); + *offset &= ~PAGE_MASK; + + /* Bytes in this sg-entry from *offset to the end of the page */ + sg_len = PAGE_SIZE - *offset; + if (*len > sg_len) + *len = sg_len; + + return kmap_atomic(page); +} +EXPORT_SYMBOL(scsi_kmap_atomic_sg); + +/** + * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg + * @virt: virtual address to be unmapped + */ +void scsi_kunmap_atomic_sg(void *virt) +{ + kunmap_atomic(virt); +} +EXPORT_SYMBOL(scsi_kunmap_atomic_sg); |