From 5f1b670d0bef508a5554d92525f5f6d00d640b38 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 22 May 2015 09:14:04 -0400 Subject: block, dm: don't copy bios for request clones Currently dm-multipath has to clone the bios for every request sent to the lower devices, which wastes cpu cycles and ties down memory. This patch instead adds a new REQ_CLONE flag that instructs req_bio_endio to not complete bios attached to a request, which we set on clone requests similar to bios in a flush sequence. With this change I/O errors on a path failure only get propagated to dm-multipath, which can then either resubmit the I/O or complete the bios on the original request. I've done some basic testing of this on a Linux target with ALUA support, and it survives path failures during I/O nicely. Signed-off-by: Christoph Hellwig Signed-off-by: Mike Snitzer Signed-off-by: Jens Axboe --- include/linux/blk_types.h | 2 ++ include/linux/blkdev.h | 6 +----- 2 files changed, 3 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 3f4ded0b1a34..45a6be89957c 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -192,6 +192,7 @@ enum rq_flag_bits { __REQ_HASHED, /* on IO scheduler merge hash */ __REQ_MQ_INFLIGHT, /* track inflight for MQ */ __REQ_NO_TIMEOUT, /* requests may never expire */ + __REQ_CLONE, /* cloned bios */ __REQ_NR_BITS, /* stops here */ }; @@ -246,5 +247,6 @@ enum rq_flag_bits { #define REQ_HASHED (1ULL << __REQ_HASHED) #define REQ_MQ_INFLIGHT (1ULL << __REQ_MQ_INFLIGHT) #define REQ_NO_TIMEOUT (1ULL << __REQ_NO_TIMEOUT) +#define REQ_CLONE (1ULL << __REQ_CLONE) #endif /* __LINUX_BLK_TYPES_H */ diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index bc917956a6d0..9ded80da2c16 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -775,11 +775,7 @@ extern void blk_add_request_payload(struct request *rq, struct page *page, unsigned int len); extern int blk_rq_check_limits(struct request_queue *q, struct request *rq); extern int blk_lld_busy(struct request_queue *q); -extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src, - struct bio_set *bs, gfp_t gfp_mask, - int (*bio_ctr)(struct bio *, struct bio *, void *), - void *data); -extern void blk_rq_unprep_clone(struct request *rq); +extern void blk_rq_prep_clone(struct request *rq, struct request *rq_src); extern int blk_insert_cloned_request(struct request_queue *q, struct request *rq); extern void blk_delay_queue(struct request_queue *, unsigned long); -- cgit v1.2.3