/*
* bsg.c - block layer implementation of the sg v4 interface
*
* Copyright (C) 2004 Jens Axboe <axboe@suse.de> SUSE Labs
* Copyright (C) 2004 Peter M. Jones <pjones@redhat.com>
*
* This file is subject to the terms and conditions of the GNU General Public
* License version 2. See the file "COPYING" in the main directory of this
* archive for more details.
*
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/blkdev.h>
#include <linux/poll.h>
#include <linux/cdev.h>
#include <linux/percpu.h>
#include <linux/uio.h>
#include <linux/idr.h>
#include <linux/bsg.h>
#include <scsi/scsi.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/sg.h>
#define BSG_DESCRIPTION "Block layer SCSI generic (bsg) driver"
#define BSG_VERSION "0.4"
struct bsg_device {
struct request_queue *queue;
spinlock_t lock;
struct list_head busy_list;
struct list_head done_list;
struct hlist_node dev_list;
atomic_t ref_count;
int minor;
int queued_cmds;
int done_cmds;
wait_queue_head_t wq_done;
wait_queue_head_t wq_free;
char name[BUS_ID_SIZE];
int max_queue;
unsigned long flags;
};
enum {
BSG_F_BLOCK = 1,
BSG_F_WRITE_PERM = 2,
};
#define BSG_DEFAULT_CMDS 64
#define BSG_MAX_DEVS 32768
#undef BSG_DEBUG
#ifdef BSG_DEBUG
#define dprintk(fmt, args...) printk(KERN_ERR "%s: " fmt, __FUNCTION__, ##args)
#else
#define dprintk(fmt, args...)
#endif
static DEFINE_MUTEX(bsg_mutex);
static DEFINE_IDR(bsg_minor_idr);
#define BSG_LIST_ARRAY_SIZE 8
static struct hlist_head bsg_device_list[BSG_LIST_ARRAY_SIZE];
static struct class *bsg_class;
static int bsg_major;
static struct kmem_cache *bsg_cmd_cachep;
/*
* our internal command type
*/
struct bsg_command {
struct bsg_device *bd;
struct list_head list;
struct request *rq;
struct bio *bio;
struct bio *bidi_bio;
int err;
struct sg_io_v4 hdr;
char sense[SCSI_SENSE_BUFFERSIZE];
};
static void bsg_free_command(struct bsg_command *bc)
{
struct bsg_device *bd = bc->bd;
unsigned long flags;
kmem_cache_free(bsg_cmd_cachep, bc);
spin_lock_irqsave(&bd->lock, flags);
bd->queued_cmds--;
spin_unlock_irqrestore(&bd->lock, flags);
wake_up(&bd->wq_free);
}
static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)
{
struct bsg_command *bc = ERR_PTR(-EINVAL);
spin_lock_irq(&bd->lock);
if (bd->queued_cmds >= bd->max_queue)
goto out;
bd->queued_cmds++;
spin_unlock_irq(&bd->lock);
bc = kmem_cache_zalloc(bsg_cmd_cachep, GFP_KERNEL);
if (unlikely(!bc)) {
spin_lock_irq(&bd->lock);
bd->queued_cmds--;
bc = ERR_PTR(-ENOMEM);
goto out;
}
bc->bd = bd;
INIT_LIST_HEAD(&bc->list);
dprintk("%s: returning free cmd %p\n", bd->name, bc);
return bc;
out:
spin_unlock_irq(&bd->lock);
return bc;
}
static inline struct hlist_head *bsg_dev_idx_hash(int index)
{
return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
}
static int bsg_io_schedule(struct bsg_device *bd)
{
DEFINE_WAIT(wait);
int ret = 0;
spin_lock_irq(&bd->lock);
BUG_ON(bd->done_cmds > bd->queued_cmds);
/*
* -ENOSPC or -ENODATA? I'm going for -ENODATA, meaning "I have no
* work to do", even though we return -ENOSPC after this same test
* during bsg_write() -- there, it means our buffer can't have more
* bsg_commands added to it, thus has no space left.
*/
if (bd->done_cmds == bd->queued_cmds) {
ret = -ENODATA;
goto unlock;
}
if (!test_bit(BSG_F_BLOCK, &bd->flags)) {
ret = -EAGAIN;
goto unlock;
}
prepare_to_wait(&bd->wq_done, &wait, TASK_UNINTERRUPTIBLE);
spin_unl