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| author | Jens Axboe <axboe@fb.com> | 2014-06-05 13:38:39 -0600 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2014-06-05 13:38:39 -0600 |
| commit | 762380ad9322951cea4ce9d24864265f9c66a916 (patch) | |
| tree | 9ec3fe551583dcb9243d02a9728511e99216dcdc /block | |
| parent | 046f153343e33dcad1be7f6249ea6ff1c6fd9b58 (diff) | |
| download | lwn-762380ad9322951cea4ce9d24864265f9c66a916.tar.gz lwn-762380ad9322951cea4ce9d24864265f9c66a916.zip | |
block: add notion of a chunk size for request merging
Some drivers have different limits on what size a request should
optimally be, depending on the offset of the request. Similar to
dividing a device into chunks. Add a setting that allows the driver
to inform the block layer of such a chunk size. The block layer will
then prevent merging across the chunks.
This is needed to optimally support NVMe with a non-zero stripe size.
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bio.c | 3 | ||||
| -rw-r--r-- | block/blk-settings.c | 18 |
2 files changed, 20 insertions, 1 deletions
diff --git a/block/bio.c b/block/bio.c index 96d28eee8a1e..97e832cc9b9c 100644 --- a/block/bio.c +++ b/block/bio.c @@ -849,7 +849,8 @@ int bio_add_page(struct bio *bio, struct page *page, unsigned int len, unsigned int offset) { struct request_queue *q = bdev_get_queue(bio->bi_bdev); - return __bio_add_page(q, bio, page, len, offset, queue_max_sectors(q)); + + return __bio_add_page(q, bio, page, len, offset, blk_max_size_offset(q, bio->bi_iter.bi_sector)); } EXPORT_SYMBOL(bio_add_page); diff --git a/block/blk-settings.c b/block/blk-settings.c index 5d21239bc859..a2b9cb195e70 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -113,6 +113,7 @@ void blk_set_default_limits(struct queue_limits *lim) lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK; lim->max_segment_size = BLK_MAX_SEGMENT_SIZE; lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS; + lim->chunk_sectors = 0; lim->max_write_same_sectors = 0; lim->max_discard_sectors = 0; lim->discard_granularity = 0; @@ -277,6 +278,23 @@ void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_secto EXPORT_SYMBOL(blk_queue_max_hw_sectors); /** + * blk_queue_chunk_sectors - set size of the chunk for this queue + * @q: the request queue for the device + * @chunk_sectors: chunk sectors in the usual 512b unit + * + * Description: + * If a driver doesn't want IOs to cross a given chunk size, it can set + * this limit and prevent merging across chunks. Note that the chunk size + * must currently be a power-of-2 in sectors. + **/ +void blk_queue_chunk_sectors(struct request_queue *q, unsigned int chunk_sectors) +{ + BUG_ON(!is_power_of_2(chunk_sectors)); + q->limits.chunk_sectors = chunk_sectors; +} +EXPORT_SYMBOL(blk_queue_chunk_sectors); + +/** * blk_queue_max_discard_sectors - set max sectors for a single discard * @q: the request queue for the device * @max_discard_sectors: maximum number of sectors to discard |