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Commit e7d72173 authored by FUJITA Tomonori's avatar FUJITA Tomonori Committed by Jens Axboe
Browse files

bsg: fix a blocking read bug 



This patch fixes a bug that read() returns ENODATA even with a
blocking file descriptor when there are no commands pending.

This also includes some cleanups.

Signed-off-by: default avatarFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 4cf0723a

block/bsg.c

+23 −61
Original line number Diff line number Diff line
@@ -115,9 +115,9 @@ static void bsg_free_command(struct bsg_command *bc) 
	wake_up(&bd->wq_free);

}



static struct bsg_command *__bsg_alloc_command(struct bsg_device *bd)

static struct bsg_command *bsg_alloc_command(struct bsg_device *bd)

{

	struct bsg_command *bc = NULL;

	struct bsg_command *bc = ERR_PTR(-EINVAL);



	spin_lock_irq(&bd->lock);
@@ -131,6 +131,7 @@ static struct bsg_command *__bsg_alloc_command(struct bsg_device *bd) 
	if (unlikely(!bc)) {

		spin_lock_irq(&bd->lock);

		bd->queued_cmds--;

		bc = ERR_PTR(-ENOMEM);

		goto out;

	}
@@ -198,30 +199,6 @@ static inline int bsg_io_schedule(struct bsg_device *bd, int state) 
	return ret;

}



/*

 * get a new free command, blocking if needed and specified

 */

static struct bsg_command *bsg_get_command(struct bsg_device *bd)

{

	struct bsg_command *bc;

	int ret;



	do {

		bc = __bsg_alloc_command(bd);

		if (bc)

			break;



		ret = bsg_io_schedule(bd, TASK_INTERRUPTIBLE);

		if (ret) {

			bc = ERR_PTR(ret);

			break;

		}



	} while (1);



	return bc;

}



static int blk_fill_sgv4_hdr_rq(request_queue_t *q, struct request *rq,

				struct sg_io_v4 *hdr, int has_write_perm)

{
@@ -397,7 +374,7 @@ static inline struct bsg_command *bsg_next_done_cmd(struct bsg_device *bd) 
/*

 * Get a finished command from the done list

 */

static struct bsg_command *__bsg_get_done_cmd(struct bsg_device *bd, int state)

static struct bsg_command *bsg_get_done_cmd(struct bsg_device *bd)

{

	struct bsg_command *bc;

	int ret;
@@ -407,9 +384,14 @@ static struct bsg_command *__bsg_get_done_cmd(struct bsg_device *bd, int state) 
		if (bc)

			break;



		ret = bsg_io_schedule(bd, state);

		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(ret);

			bc = ERR_PTR(-ERESTARTSYS);

			break;

		}

	} while (1);
@@ -419,18 +401,6 @@ static struct bsg_command *__bsg_get_done_cmd(struct bsg_device *bd, int state) 
	return bc;

}



static struct bsg_command *

bsg_get_done_cmd(struct bsg_device *bd, const struct iovec *iov)

{

	return __bsg_get_done_cmd(bd, TASK_INTERRUPTIBLE);

}



static struct bsg_command *

bsg_get_done_cmd_nosignals(struct bsg_device *bd)

{

	return __bsg_get_done_cmd(bd, TASK_UNINTERRUPTIBLE);

}



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

				    struct bio *bio)

{
@@ -496,19 +466,16 @@ static int bsg_complete_all_commands(struct bsg_device *bd) 
	 */

	ret = 0;

	do {

		bc = bsg_get_done_cmd_nosignals(bd);



		/*

		 * we _must_ complete before restarting, because

		 * bsg_release can't handle this failing.

		 */

		if (PTR_ERR(bc) == -ERESTARTSYS)

			continue;

		if (IS_ERR(bc)) {

			ret = PTR_ERR(bc);

		spin_lock_irq(&bd->lock);

		if (!bd->queued_cmds) {

			spin_unlock_irq(&bd->lock);

			break;

		}



		bc = bsg_get_done_cmd(bd);

		if (IS_ERR(bc))

			break;



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

		if (!ret)

			ret = tret;
@@ -519,11 +486,9 @@ static int bsg_complete_all_commands(struct bsg_device *bd) 
	return ret;

}



typedef struct bsg_command *(*bsg_command_callback)(struct bsg_device *bd, const struct iovec *iov);



static ssize_t

__bsg_read(char __user *buf, size_t count, bsg_command_callback get_bc,

	   struct bsg_device *bd, const struct iovec *iov, ssize_t *bytes_read)

__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;
@@ -534,7 +499,7 @@ __bsg_read(char __user *buf, size_t count, bsg_command_callback get_bc, 
	ret = 0;

	nr_commands = count / sizeof(struct sg_io_v4);

	while (nr_commands) {

		bc = get_bc(bd, iov);

		bc = bsg_get_done_cmd(bd);

		if (IS_ERR(bc)) {

			ret = PTR_ERR(bc);

			break;
@@ -598,8 +563,7 @@ bsg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 


	bsg_set_block(bd, file);

	bytes_read = 0;

	ret = __bsg_read(buf, count, bsg_get_done_cmd,

			bd, NULL, &bytes_read);

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

	*ppos = bytes_read;



	if (!bytes_read || (bytes_read && err_block_err(ret)))
@@ -625,9 +589,7 @@ static ssize_t __bsg_write(struct bsg_device *bd, const char __user *buf, 
	while (nr_commands) {

		request_queue_t *q = bd->queue;



		bc = bsg_get_command(bd);

		if (!bc)

			break;

		bc = bsg_alloc_command(bd);

		if (IS_ERR(bc)) {

			ret = PTR_ERR(bc);

			bc = NULL;