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authorChristoph Hellwig <hch@lst.de>2016-12-08 23:20:32 +0100
committerJens Axboe <axboe@fb.com>2016-12-09 16:30:51 +0100
commitf9d03f96b988002027d4b28ea1b7a24729a4c9b5 (patch)
treee4995a30bbe58290594e2ef29de5ae2785c6c9db /block/blk-core.c
parentblk-wbt: don't throttle discard or write zeroes (diff)
downloadlinux-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.c34
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 */