[mirror_zfs.git] / include / linux / blkdev_compat.h

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (C) 2011 Lawrence Livermore National Security, LLC.
 * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
 * Written by Brian Behlendorf <behlendorf1@llnl.gov>.
 * LLNL-CODE-403049.
 */

#ifndef _ZFS_BLKDEV_H
#define _ZFS_BLKDEV_H

#include <linux/blkdev.h>
#include <linux/elevator.h>

#ifndef HAVE_FMODE_T
typedef unsigned __bitwise__ fmode_t;
#endif /* HAVE_FMODE_T */

#ifndef HAVE_BLK_FETCH_REQUEST
static inline struct request *
blk_fetch_request(struct request_queue *q)
{
	struct request *req;

	req = elv_next_request(q);
	if (req)
		blkdev_dequeue_request(req);

	return req;
}
#endif /* HAVE_BLK_FETCH_REQUEST */

#ifndef HAVE_BLK_REQUEUE_REQUEST
static inline void
blk_requeue_request(request_queue_t *q, struct request *req)
{
	elv_requeue_request(q, req);
}
#endif /* HAVE_BLK_REQUEUE_REQUEST */

#ifndef HAVE_BLK_END_REQUEST
static inline bool
__blk_end_request(struct request *req, int error, unsigned int nr_bytes)
{
	LIST_HEAD(list);

	/*
	 * Request has already been dequeued but 2.6.18 version of
	 * end_request() unconditionally dequeues the request so we
	 * add it to a local list to prevent hitting the BUG_ON.
	 */
	list_add(&req->queuelist, &list);

	/*
	 * The old API required the driver to end each segment and not
	 * the entire request.  In our case we always need to end the
	 * entire request partial requests are not supported.
	 */
	req->hard_cur_sectors = nr_bytes >> 9;
	end_request(req, ((error == 0) ? 1 : error));

	return 0;
}

static inline bool
blk_end_request(struct request *req, int error, unsigned int nr_bytes)
{
	struct request_queue *q = req->q;
	bool rc;

	spin_lock_irq(q->queue_lock);
	rc = __blk_end_request(req, error, nr_bytes);
	spin_unlock_irq(q->queue_lock);

	return rc;
}
#else
# ifdef HAVE_BLK_END_REQUEST_GPL_ONLY
/*
 * Define required to avoid conflicting 2.6.29 non-static prototype for a
 * GPL-only version of the helper.  As of 2.6.31 the helper is available
 * to non-GPL modules and is not explicitly exported GPL-only.
 */
# define __blk_end_request __blk_end_request_x
# define blk_end_request blk_end_request_x

static inline bool
__blk_end_request_x(struct request *req, int error, unsigned int nr_bytes)
{
	/*
	 * The old API required the driver to end each segment and not
	 * the entire request.  In our case we always need to end the
	 * entire request partial requests are not supported.
	 */
	req->hard_cur_sectors = nr_bytes >> 9;
	end_request(req, ((error == 0) ? 1 : error));

	return 0;
}
static inline bool
blk_end_request_x(struct request *req, int error, unsigned int nr_bytes)
{
	struct request_queue *q = req->q;
	bool rc;

	spin_lock_irq(q->queue_lock);
	rc = __blk_end_request_x(req, error, nr_bytes);
	spin_unlock_irq(q->queue_lock);

	return rc;
}
# endif /* HAVE_BLK_END_REQUEST_GPL_ONLY */
#endif /* HAVE_BLK_END_REQUEST */

/*
 * 2.6.36 API change,
 * The blk_queue_flush() interface has replaced blk_queue_ordered()
 * interface.  However, while the old interface was available to all the
 * new one is GPL-only.   Thus if the GPL-only version is detected we
 * implement our own trivial helper compatibility funcion.   The hope is
 * that long term this function will be opened up.
 */
#if defined(HAVE_BLK_QUEUE_FLUSH) && defined(HAVE_BLK_QUEUE_FLUSH_GPL_ONLY)
#define blk_queue_flush __blk_queue_flush
static inline void
__blk_queue_flush(struct request_queue *q, unsigned int flags)
{
	q->flush_flags = flags & (REQ_FLUSH | REQ_FUA);
}
#endif /* HAVE_BLK_QUEUE_FLUSH && HAVE_BLK_QUEUE_FLUSH_GPL_ONLY */

#ifndef HAVE_BLK_RQ_POS
static inline sector_t
blk_rq_pos(struct request *req)
{
	return req->sector;
}
#endif /* HAVE_BLK_RQ_POS */

#ifndef HAVE_BLK_RQ_SECTORS
static inline unsigned int
blk_rq_sectors(struct request *req)
{
	return req->nr_sectors;
}
#endif /* HAVE_BLK_RQ_SECTORS */

#if !defined(HAVE_BLK_RQ_BYTES) || defined(HAVE_BLK_RQ_BYTES_GPL_ONLY)
/*
 * Define required to avoid conflicting 2.6.29 non-static prototype for a
 * GPL-only version of the helper.  As of 2.6.31 the helper is available
 * to non-GPL modules in the form of a static inline in the header.
 */
#define blk_rq_bytes __blk_rq_bytes
static inline unsigned int
__blk_rq_bytes(struct request *req)
{
	return blk_rq_sectors(req) << 9;
}
#endif /* !HAVE_BLK_RQ_BYTES || HAVE_BLK_RQ_BYTES_GPL_ONLY */

/*
 * Most of the blk_* macros were removed in 2.6.36.  Ostensibly this was
 * done to improve readability and allow easier grepping.  However, from
 * a portability stand point the macros are helpful.  Therefore the needed
 * macros are redefined here if they are missing from the kernel.
 */
#ifndef blk_fs_request
#define blk_fs_request(rq)	((rq)->cmd_type == REQ_TYPE_FS)
#endif

/*
 * 2.6.27 API change,
 * The blk_queue_stackable() queue flag was added in 2.6.27 to handle dm
 * stacking drivers.  Prior to this request stacking drivers were detected
 * by checking (q->request_fn == NULL), for earlier kernels we revert to
 * this legacy behavior.
 */
#ifndef blk_queue_stackable
#define blk_queue_stackable(q)	((q)->request_fn == NULL)
#endif

/*
 * 2.6.34 API change,
 * The blk_queue_max_hw_sectors() function replaces blk_queue_max_sectors().
 */
#ifndef HAVE_BLK_QUEUE_MAX_HW_SECTORS
#define blk_queue_max_hw_sectors __blk_queue_max_hw_sectors
static inline void
__blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
{
	blk_queue_max_sectors(q, max_hw_sectors);
}
#endif

/*
 * 2.6.34 API change,
 * The blk_queue_max_segments() function consolidates
 * blk_queue_max_hw_segments() and blk_queue_max_phys_segments().
 */
#ifndef HAVE_BLK_QUEUE_MAX_SEGMENTS
#define blk_queue_max_segments __blk_queue_max_segments
static inline void
__blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
{
	blk_queue_max_phys_segments(q, max_segments);
	blk_queue_max_hw_segments(q, max_segments);
}
#endif

/*
 * 2.6.30 API change,
 * The blk_queue_physical_block_size() function was introduced to
 * indicate the smallest I/O the device can write without incurring
 * a read-modify-write penalty.  For older kernels this is a no-op.
 */
#ifndef HAVE_BLK_QUEUE_PHYSICAL_BLOCK_SIZE
#define blk_queue_physical_block_size(q, x)	((void)(0))
#endif

/*
 * 2.6.30 API change,
 * The blk_queue_io_opt() function was added to indicate the optimal
 * I/O size for the device.  For older kernels this is a no-op.
 */
#ifndef HAVE_BLK_QUEUE_IO_OPT
#define blk_queue_io_opt(q, x)			((void)(0))
#endif

#ifndef HAVE_GET_DISK_RO
static inline int
get_disk_ro(struct gendisk *disk)
{
	int policy = 0;

	if (disk->part[0])
		policy = disk->part[0]->policy;

	return policy;
}
#endif /* HAVE_GET_DISK_RO */

#ifndef HAVE_RQ_IS_SYNC
static inline bool
rq_is_sync(struct request *req)
{
	return (req->flags & REQ_RW_SYNC);
}
#endif /* HAVE_RQ_IS_SYNC */

#ifndef HAVE_RQ_FOR_EACH_SEGMENT
struct req_iterator {
	int i;
	struct bio *bio;
};

# define for_each_bio(_bio)              \
	for (; _bio; _bio = _bio->bi_next)

# define __rq_for_each_bio(_bio, rq)    \
	if ((rq->bio))                  \
		for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)

# define rq_for_each_segment(bvl, _rq, _iter)                   \
	__rq_for_each_bio(_iter.bio, _rq)                       \
		bio_for_each_segment(bvl, _iter.bio, _iter.i)
#endif /* HAVE_RQ_FOR_EACH_SEGMENT */

/*
 * Portable helper for correctly setting the FAILFAST flags.  The
 * correct usage has changed 3 times from 2.6.12 to 2.6.38.
 */
static inline void
bio_set_flags_failfast(struct block_device *bdev, int *flags)
{
#ifdef CONFIG_BUG
	/*
	 * Disable FAILFAST for loopback devices because of the
	 * following incorrect BUG_ON() in loop_make_request().
	 * This support is also disabled for md devices because the
	 * test suite layers md devices on top of loopback devices.
	 * This may be removed when the loopback driver is fixed.
	 *
	 *   BUG_ON(!lo || (rw != READ && rw != WRITE));
	 */
	if ((MAJOR(bdev->bd_dev) == LOOP_MAJOR) ||
	    (MAJOR(bdev->bd_dev) == MD_MAJOR))
		return;

#ifdef BLOCK_EXT_MAJOR
	if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
		return;
#endif /* BLOCK_EXT_MAJOR */
#endif /* CONFIG_BUG */

#ifdef HAVE_BIO_RW_FAILFAST_DTD
	/* BIO_RW_FAILFAST_* preferred interface from 2.6.28 - 2.6.35 */
	*flags |=
	    ((1 << BIO_RW_FAILFAST_DEV) |
	     (1 << BIO_RW_FAILFAST_TRANSPORT) |
	     (1 << BIO_RW_FAILFAST_DRIVER));
#else
# ifdef HAVE_BIO_RW_FAILFAST
	/* BIO_RW_FAILFAST preferred interface from 2.6.12 - 2.6.27 */
	*flags |= (1 << BIO_RW_FAILFAST);
# else
#  ifdef HAVE_REQ_FAILFAST_MASK
	/* REQ_FAILFAST_* preferred interface from 2.6.36 - 2.6.xx,
	 * the BIO_* and REQ_* flags were unified under REQ_* flags. */
	*flags |= REQ_FAILFAST_MASK;
#  endif /* HAVE_REQ_FAILFAST_MASK */
# endif /* HAVE_BIO_RW_FAILFAST */
#endif /* HAVE_BIO_RW_FAILFAST_DTD */
}

/*
 * Maximum disk label length, it may be undefined for some kernels.
 */
#ifndef DISK_NAME_LEN
#define DISK_NAME_LEN	32
#endif /* DISK_NAME_LEN */

/*
 * 2.6.24 API change,
 * The bio_end_io() prototype changed slightly.  These are helper
 * macro's to ensure the prototype and return value are handled.
 */
#ifdef HAVE_2ARGS_BIO_END_IO_T
# define BIO_END_IO_PROTO(fn, x, y, z)	static void fn(struct bio *x, int z)
# define BIO_END_IO_RETURN(rc)		return
#else
# define BIO_END_IO_PROTO(fn, x, y, z)	static int fn(struct bio *x, \
					              unsigned int y, int z)
# define BIO_END_IO_RETURN(rc)		return rc
#endif /* HAVE_2ARGS_BIO_END_IO_T */

/*
 * 2.6.38 - 2.6.x API,
 *   blkdev_get_by_path()
 *   blkdev_put()
 *
 * 2.6.28 - 2.6.37 API,
 *   open_bdev_exclusive()
 *   close_bdev_exclusive()
 *
 * 2.6.12 - 2.6.27 API,
 *   open_bdev_excl()
 *   close_bdev_excl()
 *
 * Used to exclusively open a block device from within the kernel.
 */
#if defined(HAVE_BLKDEV_GET_BY_PATH)
# define vdev_bdev_open(path, md, hld)	blkdev_get_by_path(path, \
					    (md) | FMODE_EXCL, hld)
# define vdev_bdev_close(bdev, md)	blkdev_put(bdev, (md) | FMODE_EXCL)
#elif defined(HAVE_OPEN_BDEV_EXCLUSIVE)
# define vdev_bdev_open(path, md, hld)	open_bdev_exclusive(path, md, hld)
# define vdev_bdev_close(bdev, md)	close_bdev_exclusive(bdev, md)
#else
# define vdev_bdev_open(path, md, hld)	open_bdev_excl(path, md, hld)
# define vdev_bdev_close(bdev, md)	close_bdev_excl(bdev)
#endif /* HAVE_BLKDEV_GET_BY_PATH | HAVE_OPEN_BDEV_EXCLUSIVE */

/*
 * 2.6.22 API change
 * The function invalidate_bdev() lost it's second argument because
 * it was unused.
 */
#ifdef HAVE_1ARG_INVALIDATE_BDEV
# define vdev_bdev_invalidate(bdev)	invalidate_bdev(bdev)
#else
# define vdev_bdev_invalidate(bdev)	invalidate_bdev(bdev, 1)
#endif /* HAVE_1ARG_INVALIDATE_BDEV */

/*
 * 2.6.30 API change
 * Change to make it explicit there this is the logical block size.
 */
#ifdef HAVE_BDEV_LOGICAL_BLOCK_SIZE
# define vdev_bdev_block_size(bdev)	bdev_logical_block_size(bdev)
#else
# define vdev_bdev_block_size(bdev)	bdev_hardsect_size(bdev)
#endif

/*
 * 2.6.37 API change
 * The WRITE_FLUSH, WRITE_FUA, and WRITE_FLUSH_FUA flags have been
 * introduced as a replacement for WRITE_BARRIER.  This was done to
 * allow richer semantics to be expressed to the block layer.  It is
 * the block layers responsibility to choose the correct way to
 * implement these semantics.
 *
 * The existence of these flags implies that REQ_FLUSH an REQ_FUA are
 * defined.  Thus we can safely define VDEV_REQ_FLUSH and VDEV_REQ_FUA
 * compatibility macros.
 */
#ifdef WRITE_FLUSH_FUA
# define VDEV_WRITE_FLUSH_FUA		WRITE_FLUSH_FUA
# define VDEV_REQ_FLUSH			REQ_FLUSH
# define VDEV_REQ_FUA			REQ_FUA
#else
# define VDEV_WRITE_FLUSH_FUA		WRITE_BARRIER
# define VDEV_REQ_FLUSH			REQ_HARDBARRIER
# define VDEV_REQ_FUA			REQ_HARDBARRIER
#endif

/*
 * Default Linux IO Scheduler,
 * Setting the scheduler to noop will allow the Linux IO scheduler to
 * still perform front and back merging, while leaving the request
 * ordering and prioritization to the ZFS IO scheduler.
 */
#define	VDEV_SCHEDULER			"noop"

#endif /* _ZFS_BLKDEV_H */
Commit	Line	Data
60101509 BB	1	/*
	2	* CDDL HEADER START
	3	*
	4	* The contents of this file are subject to the terms of the
	5	* Common Development and Distribution License (the "License").
	6	* You may not use this file except in compliance with the License.
	7	*
	8	* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
	9	* or http://www.opensolaris.org/os/licensing.
	10	* See the License for the specific language governing permissions
	11	* and limitations under the License.
	12	*
	13	* When distributing Covered Code, include this CDDL HEADER in each
	14	* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
	15	* If applicable, add the following below this CDDL HEADER, with the
	16	* fields enclosed by brackets "[]" replaced with your own identifying
	17	* information: Portions Copyright [yyyy] [name of copyright owner]
	18	*
	19	* CDDL HEADER END
	20	*/
61e90960	21
60101509	22	/*
61e90960	23	* Copyright (C) 2011 Lawrence Livermore National Security, LLC.
60101509 BB	24	* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
	25	* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
	26	* LLNL-CODE-403049.
	27	*/
	28
61e90960 BB	29	#ifndef _ZFS_BLKDEV_H
61e90960 BB	30	#define _ZFS_BLKDEV_H
60101509 BB	31
	32	#include <linux/blkdev.h>
	33	#include <linux/elevator.h>
	34
	35	#ifndef HAVE_FMODE_T
	36	typedef unsigned __bitwise__ fmode_t;
	37	#endif /* HAVE_FMODE_T */
	38
	39	#ifndef HAVE_BLK_FETCH_REQUEST
	40	static inline struct request *
	41	blk_fetch_request(struct request_queue *q)
	42	{
	43	struct request *req;
	44
	45	req = elv_next_request(q);
	46	if (req)
	47	blkdev_dequeue_request(req);
	48
	49	return req;
	50	}
	51	#endif /* HAVE_BLK_FETCH_REQUEST */
	52
	53	#ifndef HAVE_BLK_REQUEUE_REQUEST
	54	static inline void
	55	blk_requeue_request(request_queue_t q, struct request req)
	56	{
	57	elv_requeue_request(q, req);
	58	}
	59	#endif /* HAVE_BLK_REQUEUE_REQUEST */
	60
	61	#ifndef HAVE_BLK_END_REQUEST
	62	static inline bool
	63	__blk_end_request(struct request *req, int error, unsigned int nr_bytes)
	64	{
	65	LIST_HEAD(list);
	66
	67	/*
	68	* Request has already been dequeued but 2.6.18 version of
	69	* end_request() unconditionally dequeues the request so we
	70	* add it to a local list to prevent hitting the BUG_ON.
	71	*/
	72	list_add(&req->queuelist, &list);
	73
	74	/*
	75	* The old API required the driver to end each segment and not
	76	* the entire request. In our case we always need to end the
	77	* entire request partial requests are not supported.
	78	*/
	79	req->hard_cur_sectors = nr_bytes >> 9;
	80	end_request(req, ((error == 0) ? 1 : error));
	81
	82	return 0;
	83	}
	84
	85	static inline bool
	86	blk_end_request(struct request *req, int error, unsigned int nr_bytes)
	87	{
	88	struct request_queue *q = req->q;
	89	bool rc;
	90
	91	spin_lock_irq(q->queue_lock);
	92	rc = __blk_end_request(req, error, nr_bytes);
	93	spin_unlock_irq(q->queue_lock);
	94
95	return rc;
96	}
97	#else
98	# ifdef HAVE_BLK_END_REQUEST_GPL_ONLY
99	/*
100	* Define required to avoid conflicting 2.6.29 non-static prototype for a
101	* GPL-only version of the helper. As of 2.6.31 the helper is available
102	* to non-GPL modules and is not explicitly exported GPL-only.
103	*/
104	# define __blk_end_request __blk_end_request_x
105	# define blk_end_request blk_end_request_x
106
107	static inline bool
108	__blk_end_request_x(struct request *req, int error, unsigned int nr_bytes)
109	{
110	/*
111	* The old API required the driver to end each segment and not
112	* the entire request. In our case we always need to end the
113	* entire request partial requests are not supported.
114	*/
115	req->hard_cur_sectors = nr_bytes >> 9;
116	end_request(req, ((error == 0) ? 1 : error));
117
118	return 0;
119	}
120	static inline bool
121	blk_end_request_x(struct request *req, int error, unsigned int nr_bytes)
122	{
123	struct request_queue *q = req->q;
124	bool rc;
125
126	spin_lock_irq(q->queue_lock);
127	rc = __blk_end_request_x(req, error, nr_bytes);
128	spin_unlock_irq(q->queue_lock);
129
130	return rc;
131	}
132	# endif /* HAVE_BLK_END_REQUEST_GPL_ONLY */
133	#endif /* HAVE_BLK_END_REQUEST */
134
b18019d2 ED	135	/*
	136	* 2.6.36 API change,
	137	* The blk_queue_flush() interface has replaced blk_queue_ordered()
	138	* interface. However, while the old interface was available to all the
	139	* new one is GPL-only. Thus if the GPL-only version is detected we
	140	* implement our own trivial helper compatibility funcion. The hope is
	141	* that long term this function will be opened up.
	142	*/
	143	#if defined(HAVE_BLK_QUEUE_FLUSH) && defined(HAVE_BLK_QUEUE_FLUSH_GPL_ONLY)
	144	#define blk_queue_flush __blk_queue_flush
	145	static inline void
	146	__blk_queue_flush(struct request_queue *q, unsigned int flags)
	147	{
	148	q->flush_flags = flags & (REQ_FLUSH \| REQ_FUA);
	149	}
	150	#endif /* HAVE_BLK_QUEUE_FLUSH && HAVE_BLK_QUEUE_FLUSH_GPL_ONLY */
	151
60101509 BB	152	#ifndef HAVE_BLK_RQ_POS
	153	static inline sector_t
	154	blk_rq_pos(struct request *req)
	155	{
	156	return req->sector;
	157	}
	158	#endif /* HAVE_BLK_RQ_POS */
	159
	160	#ifndef HAVE_BLK_RQ_SECTORS
	161	static inline unsigned int
	162	blk_rq_sectors(struct request *req)
	163	{
	164	return req->nr_sectors;
	165	}
	166	#endif /* HAVE_BLK_RQ_SECTORS */
	167
	168	#if !defined(HAVE_BLK_RQ_BYTES) \|\| defined(HAVE_BLK_RQ_BYTES_GPL_ONLY)
	169	/*
	170	* Define required to avoid conflicting 2.6.29 non-static prototype for a
	171	* GPL-only version of the helper. As of 2.6.31 the helper is available
	172	* to non-GPL modules in the form of a static inline in the header.
	173	*/
	174	#define blk_rq_bytes __blk_rq_bytes
	175	static inline unsigned int
	176	__blk_rq_bytes(struct request *req)
	177	{
	178	return blk_rq_sectors(req) << 9;
	179	}
	180	#endif /* !HAVE_BLK_RQ_BYTES \|\| HAVE_BLK_RQ_BYTES_GPL_ONLY */
	181
8326eb46 BB	182	/*
	183	* Most of the blk_* macros were removed in 2.6.36. Ostensibly this was
	184	* done to improve readability and allow easier grepping. However, from
	185	* a portability stand point the macros are helpful. Therefore the needed
	186	* macros are redefined here if they are missing from the kernel.
	187	*/
	188	#ifndef blk_fs_request
	189	#define blk_fs_request(rq) ((rq)->cmd_type == REQ_TYPE_FS)
	190	#endif
	191
3517f0b7 BB	192	/*
	193	* 2.6.27 API change,
	194	* The blk_queue_stackable() queue flag was added in 2.6.27 to handle dm
	195	* stacking drivers. Prior to this request stacking drivers were detected
	196	* by checking (q->request_fn == NULL), for earlier kernels we revert to
	197	* this legacy behavior.
	198	*/
	199	#ifndef blk_queue_stackable
	200	#define blk_queue_stackable(q) ((q)->request_fn == NULL)
	201	#endif
	202
34037afe ED	203	/*
	204	* 2.6.34 API change,
	205	* The blk_queue_max_hw_sectors() function replaces blk_queue_max_sectors().
	206	*/
	207	#ifndef HAVE_BLK_QUEUE_MAX_HW_SECTORS
	208	#define blk_queue_max_hw_sectors __blk_queue_max_hw_sectors
	209	static inline void
	210	__blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
	211	{
	212	blk_queue_max_sectors(q, max_hw_sectors);
	213	}
	214	#endif
	215
	216	/*
	217	* 2.6.34 API change,
	218	* The blk_queue_max_segments() function consolidates
	219	* blk_queue_max_hw_segments() and blk_queue_max_phys_segments().
	220	*/
	221	#ifndef HAVE_BLK_QUEUE_MAX_SEGMENTS
	222	#define blk_queue_max_segments __blk_queue_max_segments
	223	static inline void
	224	__blk_queue_max_segments(struct request_queue *q, unsigned short max_segments)
	225	{
	226	blk_queue_max_phys_segments(q, max_segments);
	227	blk_queue_max_hw_segments(q, max_segments);
	228	}
	229	#endif
	230
	231	/*
	232	* 2.6.30 API change,
	233	* The blk_queue_physical_block_size() function was introduced to
	234	* indicate the smallest I/O the device can write without incurring
	235	* a read-modify-write penalty. For older kernels this is a no-op.
	236	*/
	237	#ifndef HAVE_BLK_QUEUE_PHYSICAL_BLOCK_SIZE
	238	#define blk_queue_physical_block_size(q, x) ((void)(0))
	239	#endif
	240
	241	/*
	242	* 2.6.30 API change,
	243	* The blk_queue_io_opt() function was added to indicate the optimal
	244	* I/O size for the device. For older kernels this is a no-op.
	245	*/
	246	#ifndef HAVE_BLK_QUEUE_IO_OPT
	247	#define blk_queue_io_opt(q, x) ((void)(0))
	248	#endif
	249
60101509 BB	250	#ifndef HAVE_GET_DISK_RO
	251	static inline int
	252	get_disk_ro(struct gendisk *disk)
	253	{
	254	int policy = 0;
	255
	256	if (disk->part[0])
	257	policy = disk->part[0]->policy;
	258
	259	return policy;
	260	}
	261	#endif /* HAVE_GET_DISK_RO */
	262
	263	#ifndef HAVE_RQ_IS_SYNC
	264	static inline bool
	265	rq_is_sync(struct request *req)
	266	{
	267	return (req->flags & REQ_RW_SYNC);
	268	}
	269	#endif /* HAVE_RQ_IS_SYNC */
	270
	271	#ifndef HAVE_RQ_FOR_EACH_SEGMENT
	272	struct req_iterator {
	273	int i;
	274	struct bio *bio;
	275	};
	276
	277	# define for_each_bio(_bio) \
	278	for (; _bio; _bio = _bio->bi_next)
	279
	280	# define __rq_for_each_bio(_bio, rq) \
	281	if ((rq->bio)) \
	282	for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
	283
	284	# define rq_for_each_segment(bvl, _rq, _iter) \
	285	__rq_for_each_bio(_iter.bio, _rq) \
	286	bio_for_each_segment(bvl, _iter.bio, _iter.i)
	287	#endif /* HAVE_RQ_FOR_EACH_SEGMENT */
	288
61e90960 BB	289	/*
	290	* Portable helper for correctly setting the FAILFAST flags. The
	291	* correct usage has changed 3 times from 2.6.12 to 2.6.38.
	292	*/
2959d94a BB	293	static inline void
	294	bio_set_flags_failfast(struct block_device bdev, int flags)
	295	{
f4af6bb7	296	#ifdef CONFIG_BUG
2959d94a	297	/*
f4af6bb7 BB	298	* Disable FAILFAST for loopback devices because of the
f4af6bb7 BB	299	* following incorrect BUG_ON() in loop_make_request().
2959d94a BB	300	* This support is also disabled for md devices because the
	301	* test suite layers md devices on top of loopback devices.
	302	* This may be removed when the loopback driver is fixed.
	303	*
	304	* BUG_ON(!lo \|\| (rw != READ && rw != WRITE));
	305	*/
2959d94a BB	306	if ((MAJOR(bdev->bd_dev) == LOOP_MAJOR) \|\|
	307	(MAJOR(bdev->bd_dev) == MD_MAJOR))
	308	return;
	309
	310	#ifdef BLOCK_EXT_MAJOR
	311	if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
	312	return;
	313	#endif /* BLOCK_EXT_MAJOR */
	314	#endif /* CONFIG_BUG */
f4af6bb7 BB	315
	316	#ifdef HAVE_BIO_RW_FAILFAST_DTD
	317	/* BIO_RW_FAILFAST_* preferred interface from 2.6.28 - 2.6.35 */
2959d94a BB	318	*flags \|=
	319	((1 << BIO_RW_FAILFAST_DEV) \|
	320	(1 << BIO_RW_FAILFAST_TRANSPORT) \|
	321	(1 << BIO_RW_FAILFAST_DRIVER));
f4af6bb7 BB	322	#else
	323	# ifdef HAVE_BIO_RW_FAILFAST
	324	/* BIO_RW_FAILFAST preferred interface from 2.6.12 - 2.6.27 */
2959d94a	325	*flags \|= (1 << BIO_RW_FAILFAST);
f4af6bb7 BB	326	# else
	327	# ifdef HAVE_REQ_FAILFAST_MASK
	328	/* REQ_FAILFAST_* preferred interface from 2.6.36 - 2.6.xx,
	329	* the BIO_* and REQ_* flags were unified under REQ_* flags. */
	330	*flags \|= REQ_FAILFAST_MASK;
	331	# endif /* HAVE_REQ_FAILFAST_MASK */
	332	# endif /* HAVE_BIO_RW_FAILFAST */
	333	#endif /* HAVE_BIO_RW_FAILFAST_DTD */
2959d94a BB	334	}
2959d94a BB	335
61e90960 BB	336	/*
	337	* Maximum disk label length, it may be undefined for some kernels.
	338	*/
60101509 BB	339	#ifndef DISK_NAME_LEN
	340	#define DISK_NAME_LEN 32
	341	#endif /* DISK_NAME_LEN */
	342
61e90960 BB	343	/*
	344	* 2.6.24 API change,
	345	* The bio_end_io() prototype changed slightly. These are helper
	346	* macro's to ensure the prototype and return value are handled.
	347	*/
	348	#ifdef HAVE_2ARGS_BIO_END_IO_T
	349	# define BIO_END_IO_PROTO(fn, x, y, z) static void fn(struct bio *x, int z)
	350	# define BIO_END_IO_RETURN(rc) return
	351	#else
	352	# define BIO_END_IO_PROTO(fn, x, y, z) static int fn(struct bio *x, \
	353	unsigned int y, int z)
	354	# define BIO_END_IO_RETURN(rc) return rc
	355	#endif /* HAVE_2ARGS_BIO_END_IO_T */
	356
	357	/*
45066d1f BB	358	* 2.6.38 - 2.6.x API,
	359	* blkdev_get_by_path()
	360	* blkdev_put()
	361	*
	362	* 2.6.28 - 2.6.37 API,
	363	* open_bdev_exclusive()
	364	* close_bdev_exclusive()
	365	*
	366	* 2.6.12 - 2.6.27 API,
	367	* open_bdev_excl()
	368	* close_bdev_excl()
	369	*
61e90960 BB	370	* Used to exclusively open a block device from within the kernel.
61e90960 BB	371	*/
45066d1f BB	372	#if defined(HAVE_BLKDEV_GET_BY_PATH)
	373	# define vdev_bdev_open(path, md, hld) blkdev_get_by_path(path, \
	374	(md) \| FMODE_EXCL, hld)
	375	# define vdev_bdev_close(bdev, md) blkdev_put(bdev, (md) \| FMODE_EXCL)
	376	#elif defined(HAVE_OPEN_BDEV_EXCLUSIVE)
61e90960 BB	377	# define vdev_bdev_open(path, md, hld) open_bdev_exclusive(path, md, hld)
	378	# define vdev_bdev_close(bdev, md) close_bdev_exclusive(bdev, md)
	379	#else
	380	# define vdev_bdev_open(path, md, hld) open_bdev_excl(path, md, hld)
	381	# define vdev_bdev_close(bdev, md) close_bdev_excl(bdev)
45066d1f	382	#endif /* HAVE_BLKDEV_GET_BY_PATH \| HAVE_OPEN_BDEV_EXCLUSIVE */
61e90960 BB	383
	384	/*
	385	* 2.6.22 API change
	386	* The function invalidate_bdev() lost it's second argument because
	387	* it was unused.
	388	*/
	389	#ifdef HAVE_1ARG_INVALIDATE_BDEV
	390	# define vdev_bdev_invalidate(bdev) invalidate_bdev(bdev)
	391	#else
	392	# define vdev_bdev_invalidate(bdev) invalidate_bdev(bdev, 1)
	393	#endif /* HAVE_1ARG_INVALIDATE_BDEV */
	394
	395	/*
	396	* 2.6.30 API change
	397	* Change to make it explicit there this is the logical block size.
	398	*/
	399	#ifdef HAVE_BDEV_LOGICAL_BLOCK_SIZE
	400	# define vdev_bdev_block_size(bdev) bdev_logical_block_size(bdev)
	401	#else
	402	# define vdev_bdev_block_size(bdev) bdev_hardsect_size(bdev)
	403	#endif
	404
96801d29 BB	405	/*
	406	* 2.6.37 API change
	407	* The WRITE_FLUSH, WRITE_FUA, and WRITE_FLUSH_FUA flags have been
	408	* introduced as a replacement for WRITE_BARRIER. This was done to
	409	* allow richer semantics to be expressed to the block layer. It is
	410	* the block layers responsibility to choose the correct way to
	411	* implement these semantics.
b18019d2 ED	412	*
	413	* The existence of these flags implies that REQ_FLUSH an REQ_FUA are
	414	* defined. Thus we can safely define VDEV_REQ_FLUSH and VDEV_REQ_FUA
	415	* compatibility macros.
96801d29 BB	416	*/
	417	#ifdef WRITE_FLUSH_FUA
	418	# define VDEV_WRITE_FLUSH_FUA WRITE_FLUSH_FUA
b18019d2 ED	419	# define VDEV_REQ_FLUSH REQ_FLUSH
b18019d2 ED	420	# define VDEV_REQ_FUA REQ_FUA
96801d29 BB	421	#else
96801d29 BB	422	# define VDEV_WRITE_FLUSH_FUA WRITE_BARRIER
b18019d2 ED	423	# define VDEV_REQ_FLUSH REQ_HARDBARRIER
b18019d2 ED	424	# define VDEV_REQ_FUA REQ_HARDBARRIER
96801d29 BB	425	#endif
96801d29 BB	426
61e90960 BB	427	/*
	428	* Default Linux IO Scheduler,
	429	* Setting the scheduler to noop will allow the Linux IO scheduler to
	430	* still perform front and back merging, while leaving the request
	431	* ordering and prioritization to the ZFS IO scheduler.
	432	*/
	433	#define VDEV_SCHEDULER "noop"
60101509	434
61e90960	435	#endif /* _ZFS_BLKDEV_H */