Fix misspellings of "agressive".

[wrt350n-kernel.git] / drivers / scsi / scsi_tgt_lib.c

/*
 * SCSI target lib functions
 *
 * Copyright (C) 2005 Mike Christie <michaelc@cs.wisc.edu>
 * Copyright (C) 2005 FUJITA Tomonori <tomof@acm.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */
#include <linux/blkdev.h>
#include <linux/hash.h>
#include <linux/module.h>
#include <linux/pagemap.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tgt.h>
#include <../drivers/md/dm-bio-list.h>

#include "scsi_tgt_priv.h"

static struct workqueue_struct *scsi_tgtd;
static struct kmem_cache *scsi_tgt_cmd_cache;

/*
 * TODO: this struct will be killed when the block layer supports large bios
 * and James's work struct code is in
 */
struct scsi_tgt_cmd {
        /* TODO replace work with James b's code */
        struct work_struct work;
        /* TODO replace the lists with a large bio */
        struct bio_list xfer_done_list;
        struct bio_list xfer_list;

        struct list_head hash_list;
        struct request *rq;
        u64 tag;

        void *buffer;
        unsigned bufflen;
};

#define TGT_HASH_ORDER  4
#define cmd_hashfn(tag) hash_long((unsigned long) (tag), TGT_HASH_ORDER)

struct scsi_tgt_queuedata {
        struct Scsi_Host *shost;
        struct list_head cmd_hash[1 << TGT_HASH_ORDER];
        spinlock_t cmd_hash_lock;
};

/*
 * Function:    scsi_host_get_command()
 *
 * Purpose:     Allocate and setup a scsi command block and blk request
 *
 * Arguments:   shost   - scsi host
 *              data_dir - dma data dir
 *              gfp_mask- allocator flags
 *
 * Returns:     The allocated scsi command structure.
 *
 * This should be called by target LLDs to get a command.
 */
struct scsi_cmnd *scsi_host_get_command(struct Scsi_Host *shost,
                                        enum dma_data_direction data_dir,
                                        gfp_t gfp_mask)
{
        int write = (data_dir == DMA_TO_DEVICE);
        struct request *rq;
        struct scsi_cmnd *cmd;
        struct scsi_tgt_cmd *tcmd;

        /* Bail if we can't get a reference to the device */
        if (!get_device(&shost->shost_gendev))
                return NULL;

        tcmd = kmem_cache_alloc(scsi_tgt_cmd_cache, GFP_ATOMIC);
        if (!tcmd)
                goto put_dev;

        rq = blk_get_request(shost->uspace_req_q, write, gfp_mask);
        if (!rq)
                goto free_tcmd;

        cmd = __scsi_get_command(shost, gfp_mask);
        if (!cmd)
                goto release_rq;

        memset(cmd, 0, sizeof(*cmd));
        cmd->sc_data_direction = data_dir;
        cmd->jiffies_at_alloc = jiffies;
        cmd->request = rq;

        rq->special = cmd;
        rq->cmd_type = REQ_TYPE_SPECIAL;
        rq->cmd_flags |= REQ_TYPE_BLOCK_PC;
        rq->end_io_data = tcmd;

        bio_list_init(&tcmd->xfer_list);
        bio_list_init(&tcmd->xfer_done_list);
        tcmd->rq = rq;

        return cmd;

release_rq:
        blk_put_request(rq);
free_tcmd:
        kmem_cache_free(scsi_tgt_cmd_cache, tcmd);
put_dev:
        put_device(&shost->shost_gendev);
        return NULL;

}
EXPORT_SYMBOL_GPL(scsi_host_get_command);

/*
 * Function:    scsi_host_put_command()
 *
 * Purpose:     Free a scsi command block
 *
 * Arguments:   shost   - scsi host
 *              cmd     - command block to free
 *
 * Returns:     Nothing.
 *
 * Notes:       The command must not belong to any lists.
 */
void scsi_host_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
{
        struct request_queue *q = shost->uspace_req_q;
        struct request *rq = cmd->request;
        struct scsi_tgt_cmd *tcmd = rq->end_io_data;
        unsigned long flags;

        kmem_cache_free(scsi_tgt_cmd_cache, tcmd);

        spin_lock_irqsave(q->queue_lock, flags);
        __blk_put_request(q, rq);
        spin_unlock_irqrestore(q->queue_lock, flags);

        __scsi_put_command(shost, cmd, &shost->shost_gendev);
}
EXPORT_SYMBOL_GPL(scsi_host_put_command);

static void scsi_unmap_user_pages(struct scsi_tgt_cmd *tcmd)
{
        struct bio *bio;

        /* must call bio_endio in case bio was bounced */
        while ((bio = bio_list_pop(&tcmd->xfer_done_list))) {
                bio_endio(bio, bio->bi_size, 0);
                bio_unmap_user(bio);
        }

        while ((bio = bio_list_pop(&tcmd->xfer_list))) {
                bio_endio(bio, bio->bi_size, 0);
                bio_unmap_user(bio);
        }
}

static void cmd_hashlist_del(struct scsi_cmnd *cmd)
{
        struct request_queue *q = cmd->request->q;
        struct scsi_tgt_queuedata *qdata = q->queuedata;
        unsigned long flags;
        struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;

        spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
        list_del(&tcmd->hash_list);
        spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
}

static void scsi_tgt_cmd_destroy(struct work_struct *work)
{
        struct scsi_tgt_cmd *tcmd =
                container_of(work, struct scsi_tgt_cmd, work);
        struct scsi_cmnd *cmd = tcmd->rq->special;

        dprintk("cmd %p %d %lu\n", cmd, cmd->sc_data_direction,
                rq_data_dir(cmd->request));
        /*
         * We fix rq->cmd_flags here since when we told bio_map_user
         * to write vm for WRITE commands, blk_rq_bio_prep set
         * rq_data_dir the flags to READ.
         */
        if (cmd->sc_data_direction == DMA_TO_DEVICE)
                cmd->request->cmd_flags |= REQ_RW;
        else
                cmd->request->cmd_flags &= ~REQ_RW;

        scsi_unmap_user_pages(tcmd);
        scsi_host_put_command(scsi_tgt_cmd_to_host(cmd), cmd);
}

static void init_scsi_tgt_cmd(struct request *rq, struct scsi_tgt_cmd *tcmd,
                              u64 tag)
{
        struct scsi_tgt_queuedata *qdata = rq->q->queuedata;
        unsigned long flags;
        struct list_head *head;

        tcmd->tag = tag;
        INIT_WORK(&tcmd->work, scsi_tgt_cmd_destroy);
        spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
        head = &qdata->cmd_hash[cmd_hashfn(tag)];
        list_add(&tcmd->hash_list, head);
        spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
}

/*
 * scsi_tgt_alloc_queue - setup queue used for message passing
 * shost: scsi host
 *
 * This should be called by the LLD after host allocation.
 * And will be released when the host is released.
 */
int scsi_tgt_alloc_queue(struct Scsi_Host *shost)
{
        struct scsi_tgt_queuedata *queuedata;
        struct request_queue *q;
        int err, i;

        /*
         * Do we need to send a netlink event or should uspace
         * just respond to the hotplug event?
         */
        q = __scsi_alloc_queue(shost, NULL);
        if (!q)
                return -ENOMEM;

        queuedata = kzalloc(sizeof(*queuedata), GFP_KERNEL);
        if (!queuedata) {
                err = -ENOMEM;
                goto cleanup_queue;
        }
        queuedata->shost = shost;
        q->queuedata = queuedata;

        /*
         * this is a silly hack. We should probably just queue as many
         * command as is recvd to userspace. uspace can then make
         * sure we do not overload the HBA
         */
        q->nr_requests = shost->hostt->can_queue;
        /*
         * We currently only support software LLDs so this does
         * not matter for now. Do we need this for the cards we support?
         * If so we should make it a host template value.
         */
        blk_queue_dma_alignment(q, 0);
        shost->uspace_req_q = q;

        for (i = 0; i < ARRAY_SIZE(queuedata->cmd_hash); i++)
                INIT_LIST_HEAD(&queuedata->cmd_hash[i]);
        spin_lock_init(&queuedata->cmd_hash_lock);

        return 0;

cleanup_queue:
        blk_cleanup_queue(q);
        return err;
}
EXPORT_SYMBOL_GPL(scsi_tgt_alloc_queue);

void scsi_tgt_free_queue(struct Scsi_Host *shost)
{
        int i;
        unsigned long flags;
        struct request_queue *q = shost->uspace_req_q;
        struct scsi_cmnd *cmd;
        struct scsi_tgt_queuedata *qdata = q->queuedata;
        struct scsi_tgt_cmd *tcmd, *n;
        LIST_HEAD(cmds);

        spin_lock_irqsave(&qdata->cmd_hash_lock, flags);

        for (i = 0; i < ARRAY_SIZE(qdata->cmd_hash); i++) {
                list_for_each_entry_safe(tcmd, n, &qdata->cmd_hash[i],
                                         hash_list) {
                        list_del(&tcmd->hash_list);
                        list_add(&tcmd->hash_list, &cmds);
                }
        }

        spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);

        while (!list_empty(&cmds)) {
                tcmd = list_entry(cmds.next, struct scsi_tgt_cmd, hash_list);
                list_del(&tcmd->hash_list);
                cmd = tcmd->rq->special;

                shost->hostt->eh_abort_handler(cmd);
                scsi_tgt_cmd_destroy(&tcmd->work);
        }
}
EXPORT_SYMBOL_GPL(scsi_tgt_free_queue);

struct Scsi_Host *scsi_tgt_cmd_to_host(struct scsi_cmnd *cmd)
{
        struct scsi_tgt_queuedata *queue = cmd->request->q->queuedata;
        return queue->shost;
}
EXPORT_SYMBOL_GPL(scsi_tgt_cmd_to_host);

/*
 * scsi_tgt_queue_command - queue command for userspace processing
 * @cmd:        scsi command
 * @scsilun:    scsi lun
 * @tag:        unique value to identify this command for tmf
 */
int scsi_tgt_queue_command(struct scsi_cmnd *cmd, struct scsi_lun *scsilun,
                           u64 tag)
{
        struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
        int err;

        init_scsi_tgt_cmd(cmd->request, tcmd, tag);
        err = scsi_tgt_uspace_send_cmd(cmd, scsilun, tag);
        if (err)
                cmd_hashlist_del(cmd);

        return err;
}
EXPORT_SYMBOL_GPL(scsi_tgt_queue_command);

/*
 * This is run from a interrpt handler normally and the unmap
 * needs process context so we must queue
 */
static void scsi_tgt_cmd_done(struct scsi_cmnd *cmd)
{
        struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;

        dprintk("cmd %p %lu\n", cmd, rq_data_dir(cmd->request));

        scsi_tgt_uspace_send_status(cmd, tcmd->tag);
        queue_work(scsi_tgtd, &tcmd->work);
}

static int __scsi_tgt_transfer_response(struct scsi_cmnd *cmd)
{
        struct Scsi_Host *shost = scsi_tgt_cmd_to_host(cmd);
        int err;

        dprintk("cmd %p %lu\n", cmd, rq_data_dir(cmd->request));

        err = shost->hostt->transfer_response(cmd, scsi_tgt_cmd_done);
        switch (err) {
        case SCSI_MLQUEUE_HOST_BUSY:
        case SCSI_MLQUEUE_DEVICE_BUSY:
                return -EAGAIN;
        }

        return 0;
}

static void scsi_tgt_transfer_response(struct scsi_cmnd *cmd)
{
        struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
        int err;

        err = __scsi_tgt_transfer_response(cmd);
        if (!err)
                return;

        cmd->result = DID_BUS_BUSY << 16;
        err = scsi_tgt_uspace_send_status(cmd, tcmd->tag);
        if (err <= 0)
                /* the eh will have to pick this up */
                printk(KERN_ERR "Could not send cmd %p status\n", cmd);
}

static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask)
{
        struct request *rq = cmd->request;
        struct scsi_tgt_cmd *tcmd = rq->end_io_data;
        int count;

        cmd->use_sg = rq->nr_phys_segments;
        cmd->request_buffer = scsi_alloc_sgtable(cmd, gfp_mask);
        if (!cmd->request_buffer)
                return -ENOMEM;

        cmd->request_bufflen = rq->data_len;

        dprintk("cmd %p addr %p cnt %d %lu\n", cmd, tcmd->buffer, cmd->use_sg,
                rq_data_dir(rq));
        count = blk_rq_map_sg(rq->q, rq, cmd->request_buffer);
        if (likely(count <= cmd->use_sg)) {
                cmd->use_sg = count;
                return 0;
        }

        eprintk("cmd %p addr %p cnt %d\n", cmd, tcmd->buffer, cmd->use_sg);
        scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
        return -EINVAL;
}

/* TODO: test this crap and replace bio_map_user with new interface maybe */
static int scsi_map_user_pages(struct scsi_tgt_cmd *tcmd, struct scsi_cmnd *cmd,
                               int rw)
{
        struct request_queue *q = cmd->request->q;
        struct request *rq = cmd->request;
        void *uaddr = tcmd->buffer;
        unsigned int len = tcmd->bufflen;
        struct bio *bio;
        int err;

        while (len > 0) {
                dprintk("%lx %u\n", (unsigned long) uaddr, len);
                bio = bio_map_user(q, NULL, (unsigned long) uaddr, len, rw);
                if (IS_ERR(bio)) {
                        err = PTR_ERR(bio);
                        dprintk("fail to map %lx %u %d %x\n",
                                (unsigned long) uaddr, len, err, cmd->cmnd[0]);
                        goto unmap_bios;
                }

                uaddr += bio->bi_size;
                len -= bio->bi_size;

                /*
                 * The first bio is added and merged. We could probably
                 * try to add others using scsi_merge_bio() but for now
                 * we keep it simple. The first bio should be pretty large
                 * (either hitting the 1 MB bio pages limit or a queue limit)
                 * already but for really large IO we may want to try and
                 * merge these.
                 */
                if (!rq->bio) {
                        blk_rq_bio_prep(q, rq, bio);
                        rq->data_len = bio->bi_size;
                } else
                        /* put list of bios to transfer in next go around */
                        bio_list_add(&tcmd->xfer_list, bio);
        }

        cmd->offset = 0;
        err = scsi_tgt_init_cmd(cmd, GFP_KERNEL);
        if (err)
                goto unmap_bios;

        return 0;

unmap_bios:
        if (rq->bio) {
                bio_unmap_user(rq->bio);
                while ((bio = bio_list_pop(&tcmd->xfer_list)))
                        bio_unmap_user(bio);
        }

        return err;
}

static int scsi_tgt_transfer_data(struct scsi_cmnd *);

static void scsi_tgt_data_transfer_done(struct scsi_cmnd *cmd)
{
        struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
        struct bio *bio;
        int err;

        /* should we free resources here on error ? */
        if (cmd->result) {
send_uspace_err:
                err = scsi_tgt_uspace_send_status(cmd, tcmd->tag);
                if (err <= 0)
                        /* the tgt uspace eh will have to pick this up */
                        printk(KERN_ERR "Could not send cmd %p status\n", cmd);
                return;
        }

        dprintk("cmd %p request_bufflen %u bufflen %u\n",
                cmd, cmd->request_bufflen, tcmd->bufflen);

        scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
        bio_list_add(&tcmd->xfer_done_list, cmd->request->bio);

        tcmd->buffer += cmd->request_bufflen;
        cmd->offset += cmd->request_bufflen;

        if (!tcmd->xfer_list.head) {
                scsi_tgt_transfer_response(cmd);
                return;
        }

        dprintk("cmd2 %p request_bufflen %u bufflen %u\n",
                cmd, cmd->request_bufflen, tcmd->bufflen);

        bio = bio_list_pop(&tcmd->xfer_list);
        BUG_ON(!bio);

        blk_rq_bio_prep(cmd->request->q, cmd->request, bio);
        cmd->request->data_len = bio->bi_size;
        err = scsi_tgt_init_cmd(cmd, GFP_ATOMIC);
        if (err) {
                cmd->result = DID_ERROR << 16;
                goto send_uspace_err;
        }

        if (scsi_tgt_transfer_data(cmd)) {
                cmd->result = DID_NO_CONNECT << 16;
                goto send_uspace_err;
        }
}

static int scsi_tgt_transfer_data(struct scsi_cmnd *cmd)
{
        int err;
        struct Scsi_Host *host = scsi_tgt_cmd_to_host(cmd);

        err = host->hostt->transfer_data(cmd, scsi_tgt_data_transfer_done);
        switch (err) {
                case SCSI_MLQUEUE_HOST_BUSY:
                case SCSI_MLQUEUE_DEVICE_BUSY:
                        return -EAGAIN;
        default:
                return 0;
        }
}

static int scsi_tgt_copy_sense(struct scsi_cmnd *cmd, unsigned long uaddr,
                                unsigned len)
{
        char __user *p = (char __user *) uaddr;

        if (copy_from_user(cmd->sense_buffer, p,
                           min_t(unsigned, SCSI_SENSE_BUFFERSIZE, len))) {
                printk(KERN_ERR "Could not copy the sense buffer\n");
                return -EIO;
        }
        return 0;
}

static int scsi_tgt_abort_cmd(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
{
        struct scsi_tgt_cmd *tcmd;
        int err;

        err = shost->hostt->eh_abort_handler(cmd);
        if (err)
                eprintk("fail to abort %p\n", cmd);

        tcmd = cmd->request->end_io_data;
        scsi_tgt_cmd_destroy(&tcmd->work);
        return err;
}

static struct request *tgt_cmd_hash_lookup(struct request_queue *q, u64 tag)
{
        struct scsi_tgt_queuedata *qdata = q->queuedata;
        struct request *rq = NULL;
        struct list_head *head;
        struct scsi_tgt_cmd *tcmd;
        unsigned long flags;

        head = &qdata->cmd_hash[cmd_hashfn(tag)];
        spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
        list_for_each_entry(tcmd, head, hash_list) {
                if (tcmd->tag == tag) {
                        rq = tcmd->rq;
                        list_del(&tcmd->hash_list);
                        break;
                }
        }
        spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);

        return rq;
}

int scsi_tgt_kspace_exec(int host_no, u64 tag, int result, u32 len,
                         unsigned long uaddr, u8 rw)
{
        struct Scsi_Host *shost;
        struct scsi_cmnd *cmd;
        struct request *rq;
        struct scsi_tgt_cmd *tcmd;
        int err = 0;

        dprintk("%d %llu %d %u %lx %u\n", host_no, (unsigned long long) tag,
                result, len, uaddr, rw);

        /* TODO: replace with a O(1) alg */
        shost = scsi_host_lookup(host_no);
        if (IS_ERR(shost)) {
                printk(KERN_ERR "Could not find host no %d\n", host_no);
                return -EINVAL;
        }

        if (!shost->uspace_req_q) {
                printk(KERN_ERR "Not target scsi host %d\n", host_no);
                goto done;
        }

        rq = tgt_cmd_hash_lookup(shost->uspace_req_q, tag);
        if (!rq) {
                printk(KERN_ERR "Could not find tag %llu\n",
                       (unsigned long long) tag);
                err = -EINVAL;
                goto done;
        }
        cmd = rq->special;

        dprintk("cmd %p result %d len %d bufflen %u %lu %x\n", cmd,
                result, len, cmd->request_bufflen, rq_data_dir(rq), cmd->cmnd[0]);

        if (result == TASK_ABORTED) {
                scsi_tgt_abort_cmd(shost, cmd);
                goto done;
        }
        /*
         * store the userspace values here, the working values are
         * in the request_* values
         */
        tcmd = cmd->request->end_io_data;
        tcmd->buffer = (void *)uaddr;
        tcmd->bufflen = len;
        cmd->result = result;

        if (!tcmd->bufflen || cmd->request_buffer) {
                err = __scsi_tgt_transfer_response(cmd);
                goto done;
        }

        /*
         * TODO: Do we need to handle case where request does not
         * align with LLD.
         */
        err = scsi_map_user_pages(rq->end_io_data, cmd, rw);
        if (err) {
                eprintk("%p %d\n", cmd, err);
                err = -EAGAIN;
                goto done;
        }

        /* userspace failure */
        if (cmd->result) {
                if (status_byte(cmd->result) == CHECK_CONDITION)
                        scsi_tgt_copy_sense(cmd, uaddr, len);
                err = __scsi_tgt_transfer_response(cmd);
                goto done;
        }
        /* ask the target LLD to transfer the data to the buffer */
        err = scsi_tgt_transfer_data(cmd);

done:
        scsi_host_put(shost);
        return err;
}

int scsi_tgt_tsk_mgmt_request(struct Scsi_Host *shost, int function, u64 tag,
                              struct scsi_lun *scsilun, void *data)
{
        int err;

        /* TODO: need to retry if this fails. */
        err = scsi_tgt_uspace_send_tsk_mgmt(shost->host_no, function,
                                            tag, scsilun, data);
        if (err < 0)
                eprintk("The task management request lost!\n");
        return err;
}
EXPORT_SYMBOL_GPL(scsi_tgt_tsk_mgmt_request);

int scsi_tgt_kspace_tsk_mgmt(int host_no, u64 mid, int result)
{
        struct Scsi_Host *shost;
        int err = -EINVAL;

        dprintk("%d %d %llx\n", host_no, result, (unsigned long long) mid);

        shost = scsi_host_lookup(host_no);
        if (IS_ERR(shost)) {
                printk(KERN_ERR "Could not find host no %d\n", host_no);
                return err;
        }

        if (!shost->uspace_req_q) {
                printk(KERN_ERR "Not target scsi host %d\n", host_no);
                goto done;
        }

        err = shost->hostt->tsk_mgmt_response(mid, result);
done:
        scsi_host_put(shost);
        return err;
}

static int __init scsi_tgt_init(void)
{
        int err;

        scsi_tgt_cmd_cache = kmem_cache_create("scsi_tgt_cmd",
                                               sizeof(struct scsi_tgt_cmd),
                                               0, 0, NULL, NULL);
        if (!scsi_tgt_cmd_cache)
                return -ENOMEM;

        scsi_tgtd = create_workqueue("scsi_tgtd");
        if (!scsi_tgtd) {
                err = -ENOMEM;
                goto free_kmemcache;
        }

        err = scsi_tgt_if_init();
        if (err)
                goto destroy_wq;

        return 0;

destroy_wq:
        destroy_workqueue(scsi_tgtd);
free_kmemcache:
        kmem_cache_destroy(scsi_tgt_cmd_cache);
        return err;
}

static void __exit scsi_tgt_exit(void)
{
        destroy_workqueue(scsi_tgtd);
        scsi_tgt_if_exit();
        kmem_cache_destroy(scsi_tgt_cmd_cache);
}

module_init(scsi_tgt_init);
module_exit(scsi_tgt_exit);

MODULE_DESCRIPTION("SCSI target core");
MODULE_LICENSE("GPL");