diff options
author | Christoph Hellwig <hch@lst.de> | 2016-12-08 23:20:32 +0100 |
---|---|---|
committer | Jens Axboe <axboe@fb.com> | 2016-12-09 16:30:51 +0100 |
commit | f9d03f96b988002027d4b28ea1b7a24729a4c9b5 (patch) | |
tree | e4995a30bbe58290594e2ef29de5ae2785c6c9db /block/blk-core.c | |
parent | blk-wbt: don't throttle discard or write zeroes (diff) | |
download | linux-f9d03f96b988002027d4b28ea1b7a24729a4c9b5.tar.xz linux-f9d03f96b988002027d4b28ea1b7a24729a4c9b5.zip |
block: improve handling of the magic discard payload
Instead of allocating a single unused biovec for discard requests, send
them down without any payload. Instead we allow the driver to add a
"special" payload using a biovec embedded into struct request (unioned
over other fields never used while in the driver), and overloading
the number of segments for this case.
This has a couple of advantages:
- we don't have to allocate the bio_vec
- the amount of special casing for discard requests in the block
layer is significantly reduced
- using this same scheme for other request types is trivial,
which will be important for implementing the new WRITE_ZEROES
op on devices where it actually requires a payload (e.g. SCSI)
- we can get rid of playing games with the request length, as
we'll never touch it and completions will work just fine
- it will allow us to support ranged discard operations in the
future by merging non-contiguous discard bios into a single
request
- last but not least it removes a lot of code
This patch is the common base for my WIP series for ranges discards and to
remove discard_zeroes_data in favor of always using REQ_OP_WRITE_ZEROES,
so it would be good to get it in quickly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block/blk-core.c')
-rw-r--r-- | block/blk-core.c | 34 |
1 files changed, 2 insertions, 32 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index 4b7ec5958055..bd642a43b98b 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -1475,38 +1475,6 @@ void blk_put_request(struct request *req) } EXPORT_SYMBOL(blk_put_request); -/** - * blk_add_request_payload - add a payload to a request - * @rq: request to update - * @page: page backing the payload - * @offset: offset in page - * @len: length of the payload. - * - * This allows to later add a payload to an already submitted request by - * a block driver. The driver needs to take care of freeing the payload - * itself. - * - * Note that this is a quite horrible hack and nothing but handling of - * discard requests should ever use it. - */ -void blk_add_request_payload(struct request *rq, struct page *page, - int offset, unsigned int len) -{ - struct bio *bio = rq->bio; - - bio->bi_io_vec->bv_page = page; - bio->bi_io_vec->bv_offset = offset; - bio->bi_io_vec->bv_len = len; - - bio->bi_iter.bi_size = len; - bio->bi_vcnt = 1; - bio->bi_phys_segments = 1; - - rq->__data_len = rq->resid_len = len; - rq->nr_phys_segments = 1; -} -EXPORT_SYMBOL_GPL(blk_add_request_payload); - bool bio_attempt_back_merge(struct request_queue *q, struct request *req, struct bio *bio) { @@ -2642,6 +2610,8 @@ bool blk_update_request(struct request *req, int error, unsigned int nr_bytes) return false; } + WARN_ON_ONCE(req->rq_flags & RQF_SPECIAL_PAYLOAD); + req->__data_len -= total_bytes; /* update sector only for requests with clear definition of sector */ |