Commit 5a55c259 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by James Bottomley
Browse files

[SCSI] scsi tgt: scsi target lib functionality



The core scsi target lib functions.

TODO:
- mv md/dm-bio-list.h to linux/bio-list.h so md and us do not have to
do that weird include.
- convert scsi_tgt_cmd's work struct to James's execute code. And try
to kill our scsi_tgt_cmd.
- add host state checking. We do refcouting so hotplug is partially
supported, but we need to add state checking to make it easier on
the LLD.
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@SteelEye.com>
parent b58d9154
/*
* 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 kmem_cache_t *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(void *data)
{
struct scsi_cmnd *cmd = data;
struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
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;
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(cmd);
}
}
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);
INIT_WORK(&tcmd->work, scsi_tgt_cmd_destroy, cmd);
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)
{
int err;
err = shost->hostt->eh_abort_handler(cmd);
if (err)
eprintk("fail to abort %p\n", cmd);
scsi_tgt_cmd_destroy(cmd);
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) {