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authorChristoph Hellwig <hch@lst.de>2015-05-22 16:14:04 +0300
committerJens Axboe <axboe@fb.com>2015-05-22 17:58:57 +0300
commit5f1b670d0bef508a5554d92525f5f6d00d640b38 (patch)
tree18aaa4b5ead87568214b3d9c0f501d8a98c2a787 /fs/buffer.c
parent326e1dbb57368087a36607aaebe9795b8d5453e5 (diff)
downloadlinux-5f1b670d0bef508a5554d92525f5f6d00d640b38.tar.xz
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>
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