diff options
author | Christoph Hellwig | 2017-12-21 15:43:38 +0900 |
---|---|---|
committer | Jens Axboe | 2018-01-05 09:22:17 -0700 |
commit | 6cc77e9cb08041627fe1d32ac3a743249deb8167 (patch) | |
tree | 66303b9eb83c696b900fafc4f0c446acd6e2d72e /block | |
parent | 882d4171a8950646413b1a3cbe0e4a6a612fe82e (diff) |
block: introduce zoned block devices zone write locking
Components relying only on the request_queue structure for accessing
block devices (e.g. I/O schedulers) have a limited knowledged of the
device characteristics. In particular, the device capacity cannot be
easily discovered, which for a zoned block device also result in the
inability to easily know the number of zones of the device (the zone
size is indicated by the chunk_sectors field of the queue limits).
Introduce the nr_zones field to the request_queue structure to simplify
access to this information. Also, add the bitmap seq_zone_bitmap which
indicates which zones of the device are sequential zones (write
preferred or write required) and the bitmap seq_zones_wlock which
indicates if a zone is write locked, that is, if a write request
targeting a zone was dispatched to the device. These fields are
initialized by the low level block device driver (sd.c for ZBC/ZAC
disks). They are not initialized by stacking drivers (device mappers)
handling zoned block devices (e.g. dm-linear).
Using this, I/O schedulers can introduce zone write locking to control
request dispatching to a zoned block device and avoid write request
reordering by limiting to at most a single write request per zone
outside of the scheduler at any time.
Based on previous patches from Damien Le Moal.
Signed-off-by: Christoph Hellwig <hch@lst.de>
[Damien]
* Fixed comments and identation in blkdev.h
* Changed helper functions
* Fixed this commit message
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
-rw-r--r-- | block/blk-core.c | 1 | ||||
-rw-r--r-- | block/blk-zoned.c | 42 |
2 files changed, 43 insertions, 0 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index b8881750a3ac..e6e5bbc4c366 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1641,6 +1641,7 @@ void __blk_put_request(struct request_queue *q, struct request *req) lockdep_assert_held(q->queue_lock); + blk_req_zone_write_unlock(req); blk_pm_put_request(req); elv_completed_request(q, req); diff --git a/block/blk-zoned.c b/block/blk-zoned.c index ff57fb51b338..acb7252c7e81 100644 --- a/block/blk-zoned.c +++ b/block/blk-zoned.c @@ -22,6 +22,48 @@ static inline sector_t blk_zone_start(struct request_queue *q, } /* + * Return true if a request is a write requests that needs zone write locking. + */ +bool blk_req_needs_zone_write_lock(struct request *rq) +{ + if (!rq->q->seq_zones_wlock) + return false; + + if (blk_rq_is_passthrough(rq)) + return false; + + switch (req_op(rq)) { + case REQ_OP_WRITE_ZEROES: + case REQ_OP_WRITE_SAME: + case REQ_OP_WRITE: + return blk_rq_zone_is_seq(rq); + default: + return false; + } +} +EXPORT_SYMBOL_GPL(blk_req_needs_zone_write_lock); + +void __blk_req_zone_write_lock(struct request *rq) +{ + if (WARN_ON_ONCE(test_and_set_bit(blk_rq_zone_no(rq), + rq->q->seq_zones_wlock))) + return; + + WARN_ON_ONCE(rq->rq_flags & RQF_ZONE_WRITE_LOCKED); + rq->rq_flags |= RQF_ZONE_WRITE_LOCKED; +} +EXPORT_SYMBOL_GPL(__blk_req_zone_write_lock); + +void __blk_req_zone_write_unlock(struct request *rq) +{ + rq->rq_flags &= ~RQF_ZONE_WRITE_LOCKED; + if (rq->q->seq_zones_wlock) + WARN_ON_ONCE(!test_and_clear_bit(blk_rq_zone_no(rq), + rq->q->seq_zones_wlock)); +} +EXPORT_SYMBOL_GPL(__blk_req_zone_write_unlock); + +/* * Check that a zone report belongs to the partition. * If yes, fix its start sector and write pointer, copy it in the * zone information array and return true. Return false otherwise. |