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由 Christoph Hellwig 提交于
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: NChristoph Hellwig <hch@lst.de> Signed-off-by: NMike Snitzer <snitzer@redhat.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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