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block: Replace SG_GAPS with new queue limits mask

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The SG_GAPS queue flag caused checks for bio vector alignment against
PAGE_SIZE, but the device may have different constraints. This patch
adds a queue limits so a driver with such constraints can set to allow
requests that would have been unnecessarily split. The new gaps check
takes the request_queue as a parameter to simplify the logic around
invoking this function.

This new limit makes the queue flag redundant, so removing it and
all usage. Device-mappers will inherit the correct settings through
blk_stack_limits().

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Keith Busch 2015-08-19 14:24:05 -07:00 • committed by Jens Axboe
parent d2be537c3b
commit 03100aada9
7 changed files with 43 additions and 42 deletions
Download patch file Download diff file Expand all files Collapse all files

21
include/linux/blkdev.h
View file

@ -250,6 +250,7 @@ struct blk_queue_tag {
struct queue_limits {
unsigned long bounce_pfn;
unsigned long seg_boundary_mask;
unsigned long virt_boundary_mask;
unsigned int max_hw_sectors;
unsigned int chunk_sectors;
@ -479,7 +480,6 @@ struct request_queue {
#define QUEUE_FLAG_DEAD 19 /* queue tear-down finished */
#define QUEUE_FLAG_INIT_DONE 20 /* queue is initialized */
#define QUEUE_FLAG_NO_SG_MERGE 21 /* don't attempt to merge SG segments*/
#define QUEUE_FLAG_SG_GAPS 22 /* queue doesn't support SG gaps */
#define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \
(1 << QUEUE_FLAG_STACKABLE) | \
@ -981,6 +981,7 @@ extern int blk_queue_dma_drain(struct request_queue *q,
void *buf, unsigned int size);
extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn);
extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
extern void blk_queue_virt_boundary(struct request_queue *, unsigned long);
extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
extern void blk_queue_unprep_rq(struct request_queue *, unprep_rq_fn *ufn);
extern void blk_queue_dma_alignment(struct request_queue *, int);
@ -1149,6 +1150,11 @@ static inline unsigned long queue_segment_boundary(struct request_queue *q)
return q->limits.seg_boundary_mask;
}
static inline unsigned long queue_virt_boundary(struct request_queue *q)
{
return q->limits.virt_boundary_mask;
}
static inline unsigned int queue_max_sectors(struct request_queue *q)
{
return q->limits.max_sectors;
@ -1349,6 +1355,19 @@ static inline void put_dev_sector(Sector p)
page_cache_release(p.v);
}
/*
* Check if adding a bio_vec after bprv with offset would create a gap in
* the SG list. Most drivers don't care about this, but some do.
*/
static inline bool bvec_gap_to_prev(struct request_queue *q,
struct bio_vec *bprv, unsigned int offset)
{
if (!queue_virt_boundary(q))
return false;
return offset ||
((bprv->bv_offset + bprv->bv_len) & queue_virt_boundary(q));
}
struct work_struct;
int kblockd_schedule_work(struct work_struct *work);
int kblockd_schedule_delayed_work(struct delayed_work *dwork, unsigned long delay);