diff options
author | Christoph Hellwig <hch@lst.de> | 2016-12-08 15:20:32 -0700 |
---|---|---|
committer | Jens Axboe <axboe@fb.com> | 2016-12-09 08:30:51 -0700 |
commit | f9d03f96b988002027d4b28ea1b7a24729a4c9b5 (patch) | |
tree | e4995a30bbe58290594e2ef29de5ae2785c6c9db /drivers/nvme/host/core.c | |
parent | be07e14f96e3121483339a64d917fddb3b86ba98 (diff) | |
download | linux-f9d03f96b988002027d4b28ea1b7a24729a4c9b5.tar.bz2 |
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 'drivers/nvme/host/core.c')
-rw-r--r-- | drivers/nvme/host/core.c | 17 |
1 files changed, 4 insertions, 13 deletions
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 1b48514fbe99..3b1d6478dcfb 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -239,8 +239,6 @@ static inline int nvme_setup_discard(struct nvme_ns *ns, struct request *req, struct nvme_command *cmnd) { struct nvme_dsm_range *range; - struct page *page; - int offset; unsigned int nr_bytes = blk_rq_bytes(req); range = kmalloc(sizeof(*range), GFP_ATOMIC); @@ -257,17 +255,10 @@ static inline int nvme_setup_discard(struct nvme_ns *ns, struct request *req, cmnd->dsm.nr = 0; cmnd->dsm.attributes = cpu_to_le32(NVME_DSMGMT_AD); - req->completion_data = range; - page = virt_to_page(range); - offset = offset_in_page(range); - blk_add_request_payload(req, page, offset, sizeof(*range)); - - /* - * we set __data_len back to the size of the area to be discarded - * on disk. This allows us to report completion on the full amount - * of blocks described by the request. - */ - req->__data_len = nr_bytes; + req->special_vec.bv_page = virt_to_page(range); + req->special_vec.bv_offset = offset_in_page(range); + req->special_vec.bv_len = sizeof(*range); + req->rq_flags |= RQF_SPECIAL_PAYLOAD; return BLK_MQ_RQ_QUEUE_OK; } |