Linux 2.6.x compat, blkdev_compat.h

For legacy reasons the zvol.c and vdev_disk.c Linux compatibility
code ended up in sys/blkdev.h and sys/vdev_disk.h headers.  While
there are worse places for this code to live it should be in a
linux/blkdev_compat.h header.  This change moves this block device
Linux compatibility code in to the linux/blkdev_compat.h header
and updates all the correct #include locations.  This is not a
functional change or bug fix, it is just code cleanup.

1 files changed, 323 insertions, 0 deletions

diff --git a/include/linux/blkdev_compat.h b/include/linux/blkdev_compat.h
new file mode 100644
index 000000000..f841c6c00
--- /dev/null
+++ b/include/linux/blkdev_compat.h
@@ -0,0 +1,323 @@
+/*
+ * 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 <[email protected]>.
+ * 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 */
+
+#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
+
+#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 */
+
+/*
+ * 2.6.28 API change
+ * Used to exclusively open a block device from within the kernel.
+ */
+#ifdef 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_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
+
+/*
+ * 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 */