bsg: remove read/write support

#include <linux/init.h>

#include <linux/file.h>

#include <linux/blkdev.h>

#include <linux/poll.h>

#include <linux/cdev.h>

#include <linux/jiffies.h>

#include <linux/percpu.h>

#include <linux/uio.h>

#include <linux/idr.h>

#include <linux/bsg.h>

#include <linux/slab.h>

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 queued_cmds;

	int done_cmds;

	wait_queue_head_t wq_done;

	wait_queue_head_t wq_free;

	char name[20];

	int max_queue;

	unsigned long flags;

};

enum {

	BSG_F_BLOCK		= 1,

};

#define BSG_DEFAULT_CMDS	64

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;

};

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);

	bsg_dbg(bd, "returning free cmd %p\n", 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)];

	return ERR_PTR(ret);

}

/*

 * async completion call-back from the block layer, when scsi/ide/whatever

 * calls end_that_request_last() on a request

 */

static void bsg_rq_end_io(struct request *rq, blk_status_t status)

{

	struct bsg_command *bc = rq->end_io_data;

	struct bsg_device *bd = bc->bd;

	unsigned long flags;

	bsg_dbg(bd, "finished rq %p bc %p, bio %p\n",

		rq, bc, bc->bio);

	bc->hdr.duration = jiffies_to_msecs(jiffies - bc->hdr.duration);

	spin_lock_irqsave(&bd->lock, flags);

	list_move_tail(&bc->list, &bd->done_list);

	bd->done_cmds++;

	spin_unlock_irqrestore(&bd->lock, flags);

	wake_up(&bd->wq_done);

}

/*

 * do final setup of a 'bc' and submit the matching 'rq' to the block

 * layer for io

 */

static void bsg_add_command(struct bsg_device *bd, struct request_queue *q,

			    struct bsg_command *bc, struct request *rq)

{

	int at_head = (0 == (bc->hdr.flags & BSG_FLAG_Q_AT_TAIL));

	/*

	 * add bc command to busy queue and submit rq for io

	 */

	bc->rq = rq;

	bc->bio = rq->bio;

	if (rq->next_rq)

		bc->bidi_bio = rq->next_rq->bio;

	bc->hdr.duration = jiffies;

	spin_lock_irq(&bd->lock);

	list_add_tail(&bc->list, &bd->busy_list);

	spin_unlock_irq(&bd->lock);

	bsg_dbg(bd, "queueing rq %p, bc %p\n", rq, bc);

	rq->end_io_data = bc;

	blk_execute_rq_nowait(q, NULL, rq, at_head, bsg_rq_end_io);

}

static struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd)

{

	struct bsg_command *bc = NULL;

	spin_lock_irq(&bd->lock);

	if (bd->done_cmds) {

		bc = list_first_entry(&bd->done_list, struct bsg_command, list);

		list_del(&bc->list);

		bd->done_cmds--;

	}

	spin_unlock_irq(&bd->lock);

	return bc;

}

/*

 * Get a finished command from the done list

 */

static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)

{

	struct bsg_command *bc;

	int ret;

	do {

		bc = bsg_next_done_cmd(bd);

		if (bc)

			break;

		if (!test_bit(BSG_F_BLOCK, &bd->flags)) {

			bc = ERR_PTR(-EAGAIN);

			break;

		}

		ret = wait_event_interruptible(bd->wq_done, bd->done_cmds);

		if (ret) {

			bc = ERR_PTR(-ERESTARTSYS);

			break;

		}

	} while (1);

	bsg_dbg(bd, "returning done %p\n", bc);

	return bc;

}

static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,

				    struct bio *bio, struct bio *bidi_bio)

{

	return ret;

}

static bool bsg_complete(struct bsg_device *bd)

{

	bool ret = false;

	bool spin;

	do {

		spin_lock_irq(&bd->lock);

		BUG_ON(bd->done_cmds > bd->queued_cmds);

		/*

		 * All commands consumed.

		 */

		if (bd->done_cmds == bd->queued_cmds)

			ret = true;

		spin = !test_bit(BSG_F_BLOCK, &bd->flags);

		spin_unlock_irq(&bd->lock);

	} while (!ret && spin);

	return ret;

}

static int bsg_complete_all_commands(struct bsg_device *bd)

{

	struct bsg_command *bc;

	int ret, tret;

	bsg_dbg(bd, "entered\n");

	/*

	 * wait for all commands to complete

	 */

	io_wait_event(bd->wq_done, bsg_complete(bd));

	/*

	 * discard done commands

	 */

	ret = 0;

	do {

		spin_lock_irq(&bd->lock);

		if (!bd->queued_cmds) {

			spin_unlock_irq(&bd->lock);

			break;

		}

		spin_unlock_irq(&bd->lock);

		bc = bsg_get_done_cmd(bd);

		if (IS_ERR(bc))

			break;

		tret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,

						bc->bidi_bio);

		if (!ret)

			ret = tret;

		bsg_free_command(bc);

	} while (1);

	return ret;

}

static int

__bsg_read(char __user *buf, size_t count, struct bsg_device *bd,

	   const struct iovec *iov, ssize_t *bytes_read)

{

	struct bsg_command *bc;

	int nr_commands, ret;

	if (count % sizeof(struct sg_io_v4))

		return -EINVAL;

	ret = 0;

	nr_commands = count / sizeof(struct sg_io_v4);

	while (nr_commands) {

		bc = bsg_get_done_cmd(bd);

		if (IS_ERR(bc)) {

			ret = PTR_ERR(bc);

			break;

		}

		/*

		 * this is the only case where we need to copy data back

		 * after completing the request. so do that here,

		 * bsg_complete_work() cannot do that for us

		 */

		ret = blk_complete_sgv4_hdr_rq(bc->rq, &bc->hdr, bc->bio,

					       bc->bidi_bio);

		if (copy_to_user(buf, &bc->hdr, sizeof(bc->hdr)))

			ret = -EFAULT;

		bsg_free_command(bc);

		if (ret)

			break;

		buf += sizeof(struct sg_io_v4);

		*bytes_read += sizeof(struct sg_io_v4);

		nr_commands--;

	}

	return ret;

}

static inline void bsg_set_block(struct bsg_device *bd, struct file *file)

{

	if (file->f_flags & O_NONBLOCK)

		clear_bit(BSG_F_BLOCK, &bd->flags);

	else

		set_bit(BSG_F_BLOCK, &bd->flags);

}

/*

 * Check if the error is a "real" error that we should return.

 */

static inline int err_block_err(int ret)

{

	if (ret && ret != -ENOSPC && ret != -ENODATA && ret != -EAGAIN)

		return 1;

	return 0;

}

static ssize_t

bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)

{

	struct bsg_device *bd = file->private_data;

	int ret;

	ssize_t bytes_read;

	bsg_dbg(bd, "read %zd bytes\n", count);

	bsg_set_block(bd, file);

	bytes_read = 0;

	ret = __bsg_read(buf, count, bd, NULL, &bytes_read);

	*ppos = bytes_read;

	if (!bytes_read || err_block_err(ret))

		bytes_read = ret;

	return bytes_read;

}

static int __bsg_write(struct bsg_device *bd, const char __user *buf,

		       size_t count, ssize_t *bytes_written, fmode_t mode)

{

	struct bsg_command *bc;

	struct request *rq;

	int ret, nr_commands;

	if (count % sizeof(struct sg_io_v4))

		return -EINVAL;

	nr_commands = count / sizeof(struct sg_io_v4);

	rq = NULL;

	bc = NULL;

	ret = 0;

	while (nr_commands) {

		struct request_queue *q = bd->queue;

		bc = bsg_alloc_command(bd);

		if (IS_ERR(bc)) {

			ret = PTR_ERR(bc);

			bc = NULL;

			break;

		}

		if (copy_from_user(&bc->hdr, buf, sizeof(bc->hdr))) {

			ret = -EFAULT;

			break;

		}

		/*

		 * get a request, fill in the blanks, and add to request queue

		 */

		rq = bsg_map_hdr(bd->queue, &bc->hdr, mode);

		if (IS_ERR(rq)) {

			ret = PTR_ERR(rq);

			rq = NULL;

			break;

		}

		bsg_add_command(bd, q, bc, rq);

		bc = NULL;

		rq = NULL;

		nr_commands--;

		buf += sizeof(struct sg_io_v4);

		*bytes_written += sizeof(struct sg_io_v4);

	}

	if (bc)

		bsg_free_command(bc);

	return ret;

}

static ssize_t

bsg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)

{

	struct bsg_device *bd = file->private_data;

	ssize_t bytes_written;

	int ret;

	bsg_dbg(bd, "write %zd bytes\n", count);

	if (unlikely(uaccess_kernel()))

		return -EINVAL;

	bsg_set_block(bd, file);

	bytes_written = 0;

	ret = __bsg_write(bd, buf, count, &bytes_written, file->f_mode);

	*ppos = bytes_written;

	/*

	 * return bytes written on non-fatal errors

	 */

	if (!bytes_written || err_block_err(ret))

		bytes_written = ret;

	bsg_dbg(bd, "returning %zd\n", bytes_written);

	return bytes_written;

}

static struct bsg_device *bsg_alloc_device(void)

{

	struct bsg_device *bd;

		return NULL;

	spin_lock_init(&bd->lock);

	bd->max_queue = BSG_DEFAULT_CMDS;

	INIT_LIST_HEAD(&bd->busy_list);

	INIT_LIST_HEAD(&bd->done_list);

	INIT_HLIST_NODE(&bd->dev_list);

	init_waitqueue_head(&bd->wq_free);

	init_waitqueue_head(&bd->wq_done);

	return bd;

}

static int bsg_put_device(struct bsg_device *bd)

{

	int ret = 0, do_free;

	struct request_queue *q = bd->queue;

	mutex_lock(&bsg_mutex);

	do_free = atomic_dec_and_test(&bd->ref_count);

	if (!do_free) {

	if (!atomic_dec_and_test(&bd->ref_count)) {

		mutex_unlock(&bsg_mutex);

		goto out;

		return 0;

	}

	hlist_del(&bd->dev_list);

	/*

	 * close can always block

	 */

	set_bit(BSG_F_BLOCK, &bd->flags);

	/*

	 * correct error detection baddies here again. it's the responsibility

	 * of the app to properly reap commands before close() if it wants

	 * fool-proof error detection

	 */

	ret = bsg_complete_all_commands(bd);

	kfree(bd);

out:

	if (do_free)

	blk_put_queue(q);

	return ret;

	return 0;

}

static struct bsg_device *bsg_add_device(struct inode *inode,

	bd->queue = rq;

	bsg_set_block(bd, file);

	atomic_set(&bd->ref_count, 1);

	hlist_add_head(&bd->dev_list, bsg_dev_idx_hash(iminor(inode)));

	return bsg_put_device(bd);

}

static __poll_t bsg_poll(struct file *file, poll_table *wait)

{

	struct bsg_device *bd = file->private_data;

	__poll_t mask = 0;

	poll_wait(file, &bd->wq_done, wait);

	poll_wait(file, &bd->wq_free, wait);

	spin_lock_irq(&bd->lock);

	if (!list_empty(&bd->done_list))

		mask |= EPOLLIN | EPOLLRDNORM;

	if (bd->queued_cmds < bd->max_queue)

		mask |= EPOLLOUT;

	spin_unlock_irq(&bd->lock);

	return mask;

}

static long bsg_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

{

	struct bsg_device *bd = file->private_data;

}

static const struct file_operations bsg_fops = {

	.read		=	bsg_read,

	.write		=	bsg_write,

	.poll		=	bsg_poll,

	.open		=	bsg_open,

	.release	=	bsg_release,

	.unlocked_ioctl	=	bsg_ioctl,

	int ret, i;

	dev_t devid;

	bsg_cmd_cachep = kmem_cache_create("bsg_cmd",

				sizeof(struct bsg_command), 0, 0, NULL);

	if (!bsg_cmd_cachep) {

		printk(KERN_ERR "bsg: failed creating slab cache\n");

		return -ENOMEM;

	}

	for (i = 0; i < BSG_LIST_ARRAY_SIZE; i++)

		INIT_HLIST_HEAD(&bsg_device_list[i]);

	bsg_class = class_create(THIS_MODULE, "bsg");

	if (IS_ERR(bsg_class)) {

		ret = PTR_ERR(bsg_class);

		goto destroy_kmemcache;

	}

	if (IS_ERR(bsg_class))

		return PTR_ERR(bsg_class);

	bsg_class->devnode = bsg_devnode;

	ret = alloc_chrdev_region(&devid, 0, BSG_MAX_DEVS, "bsg");

	unregister_chrdev_region(MKDEV(bsg_major, 0), BSG_MAX_DEVS);

destroy_bsg_class:

	class_destroy(bsg_class);

destroy_kmemcache:

	kmem_cache_destroy(bsg_cmd_cachep);

	return ret;

}