Release 4.18 block/bsg.c

/*
 * 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/jiffies.h>
#include <linux/percpu.h>
#include <linux/uio.h>
#include <linux/idr.h>
#include <linux/bsg.h>
#include <linux/slab.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"


#define bsg_dbg(bd, fmt, ...) \
	pr_debug("%s: " fmt, (bd)->name, ##__VA_ARGS__)


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

#define BSG_MAX_DEVS		32768

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;
};



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);
}

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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;
}

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2
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3
2.14%
1
16.67%
Total
140
100.00%
6
100.00%



static inline struct hlist_head *bsg_dev_idx_hash(int index)
{
	return &bsg_device_list[index & (BSG_LIST_ARRAY_SIZE - 1)];
}

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1
50.00%
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25
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2
100.00%


#define uptr64(val) ((void __user *)(uintptr_t)(val))



static int bsg_scsi_check_proto(struct sg_io_v4 *hdr)
{
	if (hdr->protocol != BSG_PROTOCOL_SCSI  ||
	    hdr->subprotocol != BSG_SUB_PROTOCOL_SCSI_CMD)
		return -EINVAL;
	return 0;
}

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1
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1
3.12%
1
33.33%
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32
100.00%
3
100.00%



static int bsg_scsi_fill_hdr(struct request *rq, struct sg_io_v4 *hdr,
		fmode_t mode)
{
	struct scsi_request *sreq = scsi_req(rq);

	sreq->cmd_len = hdr->request_len;
	if (sreq->cmd_len > BLK_MAX_CDB) {
		sreq->cmd = kzalloc(sreq->cmd_len, GFP_KERNEL);
		if (!sreq->cmd)
			return -ENOMEM;
	}

	if (copy_from_user(sreq->cmd, uptr64(hdr->request), sreq->cmd_len))
		return -EFAULT;
	if (blk_verify_command(sreq->cmd, mode))
		return -EPERM;
	return 0;
}

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40
35.40%
3
37.50%
Al Viro
1
0.88%
1
12.50%
Total
113
100.00%
8
100.00%



static int bsg_scsi_complete_rq(struct request *rq, struct sg_io_v4 *hdr)
{
	struct scsi_request *sreq = scsi_req(rq);
	int ret = 0;

	/*
         * fill in all the output members
         */
	hdr->device_status = sreq->result & 0xff;
	hdr->transport_status = host_byte(sreq->result);
	hdr->driver_status = driver_byte(sreq->result);
	hdr->info = 0;
	if (hdr->device_status || hdr->transport_status || hdr->driver_status)
		hdr->info |= SG_INFO_CHECK;
	hdr->response_len = 0;

	if (sreq->sense_len && hdr->response) {
		int len = min_t(unsigned int, hdr->max_response_len,
					sreq->sense_len);

		if (copy_to_user(uptr64(hdr->response), sreq->sense, len))
			ret = -EFAULT;
		else
			hdr->response_len = len;
	}

	if (rq->next_rq) {
		hdr->dout_resid = sreq->resid_len;
		hdr->din_resid = scsi_req(rq->next_rq)->resid_len;
	} else if (rq_data_dir(rq) == READ) {
		hdr->din_resid = sreq->resid_len;
	} else {
		hdr->dout_resid = sreq->resid_len;
	}

	return ret;
}

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Jens Axboe
9
4.23%
1
16.67%
Linus Torvalds
6
2.82%
1
16.67%
Randy Dunlap
2
0.94%
1
16.67%
Total
213
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6
100.00%



static void bsg_scsi_free_rq(struct request *rq)
{
	scsi_req_free_cmd(scsi_req(rq));
}

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100.00%


static const struct bsg_ops bsg_scsi_ops = {
	.check_proto		= bsg_scsi_check_proto,
	.fill_hdr		= bsg_scsi_fill_hdr,
	.complete_rq		= bsg_scsi_complete_rq,
	.free_rq		= bsg_scsi_free_rq,
};


static struct request *

bsg_map_hdr(struct request_queue *q, struct sg_io_v4 *hdr, fmode_t mode)
{
	struct request *rq, *next_rq = NULL;
	int ret;

	if (!q->bsg_dev.class_dev)
		return ERR_PTR(-ENXIO);

	if (hdr->guard != 'Q')
		return ERR_PTR(-EINVAL);

	ret = q->bsg_dev.ops->check_proto(hdr);
	if (ret)
		return ERR_PTR(ret);

	rq = blk_get_request(q, hdr->dout_xfer_len ?
			REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);
	if (IS_ERR(rq))
		return rq;

	ret = q->bsg_dev.ops->fill_hdr(rq, hdr, mode);
	if (ret)
		goto out;

	rq->timeout = msecs_to_jiffies(hdr->timeout);
	if (!rq->timeout)
		rq->timeout = q->sg_timeout;
	if (!rq->timeout)
		rq->timeout = BLK_DEFAULT_SG_TIMEOUT;
	if (rq->timeout < BLK_MIN_SG_TIMEOUT)
		rq->timeout = BLK_MIN_SG_TIMEOUT;

	if (hdr->dout_xfer_len && hdr->din_xfer_len) {
		if (!test_bit(QUEUE_FLAG_BIDI, &q->queue_flags)) {
			ret = -EOPNOTSUPP;
			goto out;
		}

		next_rq = blk_get_request(q, REQ_OP_SCSI_IN, 0);
		if (IS_ERR(next_rq)) {
			ret = PTR_ERR(next_rq);
			goto out;
		}

		rq->next_rq = next_rq;
		ret = blk_rq_map_user(q, next_rq, NULL, uptr64(hdr->din_xferp),
				       hdr->din_xfer_len, GFP_KERNEL);
		if (ret)
			goto out_free_nextrq;
	}

	if (hdr->dout_xfer_len) {
		ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr->dout_xferp),
				hdr->dout_xfer_len, GFP_KERNEL);
	} else if (hdr->din_xfer_len) {
		ret = blk_rq_map_user(q, rq, NULL, uptr64(hdr->din_xferp),
				hdr->din_xfer_len, GFP_KERNEL);
	}

	if (ret)
		goto out_unmap_nextrq;
	return rq;

out_unmap_nextrq:
	if (rq->next_rq)
		blk_rq_unmap_user(rq->next_rq->bio);
out_free_nextrq:
	if (rq->next_rq)
		blk_put_request(rq->next_rq);
out:
	q->bsg_dev.ops->free_rq(rq);
	blk_put_request(rq);
	return ERR_PTR(ret);
}

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28.47%
6
40.00%
Jens Axboe
103
24.24%
2
13.33%
James Smart
13
3.06%
1
6.67%
Joe Lawrence
11
2.59%
1
6.67%
Al Viro
1
0.24%
1
6.67%
Total
425
100.00%
15
100.00%

/*
 * 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);
}

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3
2.63%
1
25.00%
Christoph Hellwig
2
1.75%
1
25.00%
Total
114
100.00%
4
100.00%

/*
 * 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);
}

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18
12.77%
1
16.67%
FUJITA Tomonori
17
12.06%
2
33.33%
Johannes Thumshirn
3
2.13%
1
16.67%
Total
141
100.00%
6
100.00%



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;
}

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2.67%
1
33.33%
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75
100.00%
3
100.00%

/*
 * 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;
}

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31.43%
1
20.00%
Christoph Hellwig
32
30.48%
1
20.00%
Total
105
100.00%
5
100.00%



static int blk_complete_sgv4_hdr_rq(struct request *rq, struct sg_io_v4 *hdr,
				    struct bio *bio, struct bio *bidi_bio)
{
	int ret;

	ret = rq->q->bsg_dev.ops->complete_rq(rq, hdr);

	if (rq->next_rq) {
		blk_rq_unmap_user(bidi_bio);
		blk_put_request(rq->next_rq);
	}

	blk_rq_unmap_user(bio);
	rq->q->bsg_dev.ops->free_rq(rq);
	blk_put_request(rq);
	return ret;
}

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55
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38.04%
4
57.14%
James Bottomley
2
2.17%
1
14.29%
Total
92
100.00%
7
100.00%



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;
}

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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;
}

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26.06%
4
57.14%
Peter Zijlstra
8
5.63%
1
14.29%
Johannes Thumshirn
3
2.11%
1
14.29%
Total
142
100.00%
7
100.00%


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;
}

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5.65%
3
60.00%
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177
100.00%
5
100.00%



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);
}

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/*
 * 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;
}

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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;
}

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93
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3
3.12%
1
50.00%
Total
96
100.00%
2
100.00%



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;
}

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3
33.33%
Christoph Hellwig
4
1.69%
2
22.22%
Al Viro
1
0.42%
1
11.11%
Total
237
100.00%
9
100.00%


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;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Jens Axboe
99
81.82%
2
33.33%
Al Viro
12
9.92%
2
33.33%
Johannes Thumshirn
6
4.96%
1
16.67%
FUJITA Tomonori
4
3.31%
1
16.67%
Total
121
100.00%
6
100.00%



static struct bsg_device *bsg_alloc_device(void)
{
	struct bsg_device *bd;

	bd = kzalloc(sizeof(struct bsg_device), GFP_KERNEL);
	if (unlikely(!bd))
		return NULL;

	spin_lock_init(&bd->lock);

	bd->max_queue = BSG