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 --- drivers/md/dm.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'drivers/md/dm.h') diff --git a/drivers/md/dm.h b/drivers/md/dm.h index 6123c2bf9150..e6e66d087b26 100644 --- a/drivers/md/dm.h +++ b/drivers/md/dm.h @@ -222,8 +222,9 @@ void dm_kcopyd_exit(void); /* * Mempool operations */ -struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, unsigned type, - unsigned integrity, unsigned per_bio_data_size); +struct dm_md_mempools *dm_alloc_bio_mempools(unsigned integrity, + unsigned per_bio_data_size); +struct dm_md_mempools *dm_alloc_rq_mempools(struct mapped_device *md, unsigned type); void dm_free_md_mempools(struct dm_md_mempools *pools); /* -- cgit v1.2.1