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authorMartin K. Petersen <martin.petersen@oracle.com>2009-06-16 08:23:52 +0200
committerJens Axboe <jens.axboe@oracle.com>2009-06-16 08:23:52 +0200
commite475bba2fdee9c3dbfe25f026f8fb8de69508ad2 (patch)
treecb2a050b58fbd8cd7a4d82349164622fedc2c6d0 /block/blk-settings.c
parent6923715ae39ed39ac2fc1993e5061668f4f71ad0 (diff)
downloadlinux-2.6.34-ux500-e475bba2fdee9c3dbfe25f026f8fb8de69508ad2.tar.gz
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>
Diffstat (limited to 'block/blk-settings.c')
-rw-r--r--block/blk-settings.c33
1 files changed, 27 insertions, 6 deletions
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 138610b9895..7541ea4bf9f 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
*/