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| author | Martin K. Petersen <martin.petersen@oracle.com> | 2009-06-16 08:23:52 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-06-16 08:23:52 +0200 |
| commit | e475bba2fdee9c3dbfe25f026f8fb8de69508ad2 (patch) | |
| tree | cb2a050b58fbd8cd7a4d82349164622fedc2c6d0 | |
| parent | 6923715ae39ed39ac2fc1993e5061668f4f71ad0 (diff) | |
| download | linux-e475bba2fdee9c3dbfe25f026f8fb8de69508ad2.tar.gz linux-e475bba2fdee9c3dbfe25f026f8fb8de69508ad2.tar.bz2 linux-e475bba2fdee9c3dbfe25f026f8fb8de69508ad2.zip | |
block: Introduce helper to reset queue limits to default values
DM reuses the request queue when swapping in a new device table
Introduce blk_set_default_limits() which can be used to reset the the
queue_limits prior to stacking devices.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Alasdair G Kergon <agk@redhat.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
| -rw-r--r-- | block/blk-settings.c | 33 | ||||
| -rw-r--r-- | include/linux/blkdev.h | 1 |
2 files changed, 28 insertions, 6 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c index 138610b98956..7541ea4bf9fe 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -96,6 +96,31 @@ void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn) EXPORT_SYMBOL_GPL(blk_queue_lld_busy); /** + * blk_set_default_limits - reset limits to default values + * @limits: the queue_limits structure to reset + * + * Description: + * Returns a queue_limit struct to its default state. Can be used by + * stacking drivers like DM that stage table swaps and reuse an + * existing device queue. + */ +void blk_set_default_limits(struct queue_limits *lim) +{ + lim->max_phys_segments = MAX_PHYS_SEGMENTS; + lim->max_hw_segments = MAX_HW_SEGMENTS; + lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; + lim->max_segment_size = MAX_SEGMENT_SIZE; + lim->max_sectors = lim->max_hw_sectors = SAFE_MAX_SECTORS; + lim->logical_block_size = lim->physical_block_size = lim->io_min = 512; + lim->bounce_pfn = BLK_BOUNCE_ANY; + lim->alignment_offset = 0; + lim->io_opt = 0; + lim->misaligned = 0; + lim->no_cluster = 0; +} +EXPORT_SYMBOL(blk_set_default_limits); + +/** * blk_queue_make_request - define an alternate make_request function for a device * @q: the request queue for the device to be affected * @mfn: the alternate make_request function @@ -123,14 +148,8 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) * set defaults */ q->nr_requests = BLKDEV_MAX_RQ; - blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS); - blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS); - blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK); - blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE); q->make_request_fn = mfn; - blk_queue_max_sectors(q, SAFE_MAX_SECTORS); - blk_queue_logical_block_size(q, 512); blk_queue_dma_alignment(q, 511); blk_queue_congestion_threshold(q); q->nr_batching = BLK_BATCH_REQ; @@ -143,6 +162,8 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn) q->unplug_timer.function = blk_unplug_timeout; q->unplug_timer.data = (unsigned long)q; + blk_set_default_limits(&q->limits); + /* * by default assume old behaviour and bounce for any highmem page */ diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 0b1a6cae9de1..8963d9149b5f 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -926,6 +926,7 @@ extern void blk_queue_alignment_offset(struct request_queue *q, unsigned int alignment); extern void blk_queue_io_min(struct request_queue *q, unsigned int min); extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt); +extern void blk_set_default_limits(struct queue_limits *lim); extern int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, sector_t offset); extern void disk_stack_limits(struct gendisk *disk, struct block_device *bdev, |