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2959d94a0a
ZFS works best when it is notified as soon as possible when a device failure occurs. This allows it to immediately start any recovery actions which may be needed. In theory Linux supports a flag which can be set on bio's called FAILFAST which provides this quick notification by disabling the retry logic in the lower scsi layers. That's the theory at least. In practice is turns out that while the flag exists you oddly have to set it with the BIO_RW_AHEAD flag. And even when it's set it you may get retries in the low level drivers decides that's the right behavior, or if you don't get the right error codes reported to the scsi midlayer. Unfortunately, without additional kernels patchs there's not much which can be done to improve this. Basically, this just means that it may take 2-3 minutes before a ZFS is notified properly that a device has failed. This can be improved and I suspect I'll be submitting patches upstream to handle this.
244 lines
6.3 KiB
C
244 lines
6.3 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (C) 2008-2010 Lawrence Livermore National Security, LLC.
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* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
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* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
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* LLNL-CODE-403049.
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*/
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#ifndef _SYS_BLKDEV_H
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#define _SYS_BLKDEV_H
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#ifdef _KERNEL
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#include <linux/blkdev.h>
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#include <linux/elevator.h>
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#ifndef HAVE_FMODE_T
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typedef unsigned __bitwise__ fmode_t;
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#endif /* HAVE_FMODE_T */
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#ifndef HAVE_BLK_FETCH_REQUEST
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static inline struct request *
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blk_fetch_request(struct request_queue *q)
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{
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struct request *req;
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req = elv_next_request(q);
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if (req)
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blkdev_dequeue_request(req);
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return req;
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}
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#endif /* HAVE_BLK_FETCH_REQUEST */
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#ifndef HAVE_BLK_REQUEUE_REQUEST
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static inline void
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blk_requeue_request(request_queue_t *q, struct request *req)
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{
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elv_requeue_request(q, req);
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}
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#endif /* HAVE_BLK_REQUEUE_REQUEST */
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#ifndef HAVE_BLK_END_REQUEST
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static inline bool
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__blk_end_request(struct request *req, int error, unsigned int nr_bytes)
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{
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LIST_HEAD(list);
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/*
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* Request has already been dequeued but 2.6.18 version of
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* end_request() unconditionally dequeues the request so we
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* add it to a local list to prevent hitting the BUG_ON.
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*/
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list_add(&req->queuelist, &list);
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/*
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* The old API required the driver to end each segment and not
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* the entire request. In our case we always need to end the
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* entire request partial requests are not supported.
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*/
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req->hard_cur_sectors = nr_bytes >> 9;
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end_request(req, ((error == 0) ? 1 : error));
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return 0;
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}
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static inline bool
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blk_end_request(struct request *req, int error, unsigned int nr_bytes)
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{
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struct request_queue *q = req->q;
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bool rc;
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spin_lock_irq(q->queue_lock);
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rc = __blk_end_request(req, error, nr_bytes);
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spin_unlock_irq(q->queue_lock);
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return rc;
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}
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#else
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# ifdef HAVE_BLK_END_REQUEST_GPL_ONLY
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/*
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* Define required to avoid conflicting 2.6.29 non-static prototype for a
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* GPL-only version of the helper. As of 2.6.31 the helper is available
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* to non-GPL modules and is not explicitly exported GPL-only.
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*/
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# define __blk_end_request __blk_end_request_x
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# define blk_end_request blk_end_request_x
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static inline bool
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__blk_end_request_x(struct request *req, int error, unsigned int nr_bytes)
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{
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/*
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* The old API required the driver to end each segment and not
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* the entire request. In our case we always need to end the
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* entire request partial requests are not supported.
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*/
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req->hard_cur_sectors = nr_bytes >> 9;
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end_request(req, ((error == 0) ? 1 : error));
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return 0;
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}
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static inline bool
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blk_end_request_x(struct request *req, int error, unsigned int nr_bytes)
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{
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struct request_queue *q = req->q;
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bool rc;
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spin_lock_irq(q->queue_lock);
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rc = __blk_end_request_x(req, error, nr_bytes);
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spin_unlock_irq(q->queue_lock);
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return rc;
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}
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# endif /* HAVE_BLK_END_REQUEST_GPL_ONLY */
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#endif /* HAVE_BLK_END_REQUEST */
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#ifndef HAVE_BLK_RQ_POS
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static inline sector_t
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blk_rq_pos(struct request *req)
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{
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return req->sector;
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}
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#endif /* HAVE_BLK_RQ_POS */
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#ifndef HAVE_BLK_RQ_SECTORS
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static inline unsigned int
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blk_rq_sectors(struct request *req)
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{
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return req->nr_sectors;
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}
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#endif /* HAVE_BLK_RQ_SECTORS */
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#if !defined(HAVE_BLK_RQ_BYTES) || defined(HAVE_BLK_RQ_BYTES_GPL_ONLY)
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/*
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* Define required to avoid conflicting 2.6.29 non-static prototype for a
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* GPL-only version of the helper. As of 2.6.31 the helper is available
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* to non-GPL modules in the form of a static inline in the header.
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*/
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#define blk_rq_bytes __blk_rq_bytes
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static inline unsigned int
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__blk_rq_bytes(struct request *req)
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{
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return blk_rq_sectors(req) << 9;
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}
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#endif /* !HAVE_BLK_RQ_BYTES || HAVE_BLK_RQ_BYTES_GPL_ONLY */
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#ifndef HAVE_GET_DISK_RO
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static inline int
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get_disk_ro(struct gendisk *disk)
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{
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int policy = 0;
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if (disk->part[0])
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policy = disk->part[0]->policy;
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return policy;
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}
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#endif /* HAVE_GET_DISK_RO */
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#ifndef HAVE_RQ_IS_SYNC
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static inline bool
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rq_is_sync(struct request *req)
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{
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return (req->flags & REQ_RW_SYNC);
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}
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#endif /* HAVE_RQ_IS_SYNC */
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#ifndef HAVE_RQ_FOR_EACH_SEGMENT
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struct req_iterator {
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int i;
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struct bio *bio;
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};
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# define for_each_bio(_bio) \
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for (; _bio; _bio = _bio->bi_next)
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# define __rq_for_each_bio(_bio, rq) \
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if ((rq->bio)) \
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for (_bio = (rq)->bio; _bio; _bio = _bio->bi_next)
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# define rq_for_each_segment(bvl, _rq, _iter) \
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__rq_for_each_bio(_iter.bio, _rq) \
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bio_for_each_segment(bvl, _iter.bio, _iter.i)
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#endif /* HAVE_RQ_FOR_EACH_SEGMENT */
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static inline void
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bio_set_flags_failfast(struct block_device *bdev, int *flags)
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{
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#ifdef HAVE_BIO_RW_FAILFAST
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/*
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* Disable BIO_RW_FAILFAST_* for loopback devices because of
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* the following incorrect BUG_ON() in loop_make_request().
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* This support is also disabled for md devices because the
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* test suite layers md devices on top of loopback devices.
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* This may be removed when the loopback driver is fixed.
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*
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* BUG_ON(!lo || (rw != READ && rw != WRITE));
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*/
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#ifdef CONFIG_BUG
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if ((MAJOR(bdev->bd_dev) == LOOP_MAJOR) ||
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(MAJOR(bdev->bd_dev) == MD_MAJOR))
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return;
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#ifdef BLOCK_EXT_MAJOR
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if (MAJOR(bdev->bd_dev) == BLOCK_EXT_MAJOR)
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return;
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#endif /* BLOCK_EXT_MAJOR */
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#endif /* CONFIG_BUG */
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*flags |=
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((1 << BIO_RW_FAILFAST_DEV) |
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(1 << BIO_RW_FAILFAST_TRANSPORT) |
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(1 << BIO_RW_FAILFAST_DRIVER));
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#else /* !HAVE_BIO_RW_FAILFAST */
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*flags |= (1 << BIO_RW_FAILFAST);
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#endif /* HAVE_BIO_RW_FAILFAST */
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}
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#ifndef DISK_NAME_LEN
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#define DISK_NAME_LEN 32
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#endif /* DISK_NAME_LEN */
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#endif /* KERNEL */
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#endif /* _SYS_BLKDEV_H */
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