diff options
| author | Christoph Hellwig <hch@lst.de> | 2015-05-22 09:14:04 -0400 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-05-22 08:58:57 -0600 |
| commit | 5f1b670d0bef508a5554d92525f5f6d00d640b38 (patch) | |
| tree | 18aaa4b5ead87568214b3d9c0f501d8a98c2a787 /include/linux/blk_types.h | |
| parent | 326e1dbb57368087a36607aaebe9795b8d5453e5 (diff) | |
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 <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/blk_types.h')
| -rw-r--r-- | include/linux/blk_types.h | 2 |
1 files changed, 2 insertions, 0 deletions
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 */ |