From 1e739730c5b9ea80a2f25e9cf6e1025d47e3d8ed Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 8 Feb 2017 14:46:49 +0100 Subject: block: optionally merge discontiguous discard bios into a single request Add a new merge strategy that merges discard bios into a request until the maximum number of discard ranges (or the maximum discard size) is reached from the plug merging code. I/O scheduler merging is not wired up yet but might also be useful, although not for fast devices like NVMe which are the only user for now. Note that for now we don't support limiting the size of each discard range, but if needed that can be added later. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- block/blk-settings.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'block/blk-settings.c') diff --git a/block/blk-settings.c b/block/blk-settings.c index 6eb19bcbf3cb..1e7174ffc9d4 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -88,6 +88,7 @@ EXPORT_SYMBOL_GPL(blk_queue_lld_busy); void blk_set_default_limits(struct queue_limits *lim) { lim->max_segments = BLK_MAX_SEGMENTS; + lim->max_discard_segments = 1; lim->max_integrity_segments = 0; lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; lim->virt_boundary_mask = 0; @@ -128,6 +129,7 @@ void blk_set_stacking_limits(struct queue_limits *lim) /* Inherit limits from component devices */ lim->discard_zeroes_data = 1; lim->max_segments = USHRT_MAX; + lim->max_discard_segments = 1; lim->max_hw_sectors = UINT_MAX; lim->max_segment_size = UINT_MAX; lim->max_sectors = UINT_MAX; @@ -336,6 +338,22 @@ void blk_queue_max_segments(struct request_queue *q, unsigned short max_segments } EXPORT_SYMBOL(blk_queue_max_segments); +/** + * blk_queue_max_discard_segments - set max segments for discard requests + * @q: the request queue for the device + * @max_segments: max number of segments + * + * Description: + * Enables a low level driver to set an upper limit on the number of + * segments in a discard request. + **/ +void blk_queue_max_discard_segments(struct request_queue *q, + unsigned short max_segments) +{ + q->limits.max_discard_segments = max_segments; +} +EXPORT_SYMBOL_GPL(blk_queue_max_discard_segments); + /** * blk_queue_max_segment_size - set max segment size for blk_rq_map_sg * @q: the request queue for the device @@ -553,6 +571,8 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, b->virt_boundary_mask); t->max_segments = min_not_zero(t->max_segments, b->max_segments); + t->max_discard_segments = min_not_zero(t->max_discard_segments, + b->max_discard_segments); t->max_integrity_segments = min_not_zero(t->max_integrity_segments, b->max_integrity_segments); -- cgit v1.2.3-70-g09d2