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.

Martin K. Petersen committed 17 years ago

Commit e475bba1 parent 69237152 files · +28 −6Browse files

Unified · Split

2 files

block/blk-settings.c +27 −6
include/linux/blkdev.h +1 −0

block/blk-settings.c+27−6

@@ -95,6 +95,31 @@ void blk_queue_lld_busy(struct request_queue q, lld_busy_fn fn) · 94 unmodified lines
95	95	}
96	96	EXPORT_SYMBOL_GPL(blk_queue_lld_busy);
97	97
	98	+/**
	99	+ * blk_set_default_limits - reset limits to default values
	100	+ * @limits: the queue_limits structure to reset
	101	+ *
	102	+ * Description:
	103	+ * Returns a queue_limit struct to its default state. Can be used by
	104	+ * stacking drivers like DM that stage table swaps and reuse an
	105	+ * existing device queue.
	106	+ */
	107	+void blk_set_default_limits(struct queue_limits *lim)
	108	+{
	109	+ lim->max_phys_segments = MAX_PHYS_SEGMENTS;
	110	+ lim->max_hw_segments = MAX_HW_SEGMENTS;
	111	+ lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
	112	+ lim->max_segment_size = MAX_SEGMENT_SIZE;
	113	+ lim->max_sectors = lim->max_hw_sectors = SAFE_MAX_SECTORS;
	114	+ lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
	115	+ lim->bounce_pfn = BLK_BOUNCE_ANY;
	116	+ lim->alignment_offset = 0;
	117	+ lim->io_opt = 0;
	118	+ lim->misaligned = 0;
	119	+ lim->no_cluster = 0;
	120	+}
	121	+EXPORT_SYMBOL(blk_set_default_limits);
	122	+
98	123	/**
99	124	* blk_queue_make_request - define an alternate make_request function for a device
100	125	* @q: the request queue for the device to be affected
@@ -123,14 +148,8 @@ void blk_queue_make_request(struct request_queue q, make_request_fn mfn) · 22 unmodified lines
123	148	* set defaults
124	149	*/
125	150	q->nr_requests = BLKDEV_MAX_RQ;
126		− blk_queue_max_phys_segments(q, MAX_PHYS_SEGMENTS);
127		− blk_queue_max_hw_segments(q, MAX_HW_SEGMENTS);
128		− blk_queue_segment_boundary(q, BLK_SEG_BOUNDARY_MASK);
129		− blk_queue_max_segment_size(q, MAX_SEGMENT_SIZE);
130	151
131	152	q->make_request_fn = mfn;
132		− blk_queue_max_sectors(q, SAFE_MAX_SECTORS);
133		− blk_queue_logical_block_size(q, 512);
134	153	blk_queue_dma_alignment(q, 511);
135	154	blk_queue_congestion_threshold(q);
136	155	q->nr_batching = BLK_BATCH_REQ;
@@ -143,6 +162,8 @@ void blk_queue_make_request(struct request_queue q, make_request_fn mfn) · 6 unmodified lines
143	162	q->unplug_timer.function = blk_unplug_timeout;
144	163	q->unplug_timer.data = (unsigned long)q;
145	164
	165	+ blk_set_default_limits(&q->limits);
	166	+
146	167	/*
147	168	* by default assume old behaviour and bounce for any highmem page
148	169	*/

include/linux/blkdev.h+1−0

@@ -926,6 +926,7 @@ extern void blk_queue_alignment_offset(struct request_queue *q, · 925 unmodified lines
926	926	unsigned int alignment);
927	927	extern void blk_queue_io_min(struct request_queue *q, unsigned int min);
928	928	extern void blk_queue_io_opt(struct request_queue *q, unsigned int opt);
	929	+extern void blk_set_default_limits(struct queue_limits *lim);
929	930	extern int blk_stack_limits(struct queue_limits t, struct queue_limits b,
930	931	sector_t offset);
931	932	extern void disk_stack_limits(struct gendisk disk, struct block_device bdev,