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authorChristoph Hellwig <hch@lst.de>2017-11-02 14:59:30 +0300
committerJens Axboe <axboe@kernel.dk>2017-11-11 05:53:25 +0300
commit32acab3181c7053c775ca128c3a5c6ce50197d7f (patch)
tree499c4cd6962b30028b788db9a68573c0de6bca25 /drivers/nvme/host/Kconfig
parented754e5deeb17f4e675c84e4b6c640cc7344e498 (diff)
downloadlinux-32acab3181c7053c775ca128c3a5c6ce50197d7f.tar.xz
nvme: implement multipath access to nvme subsystems
This patch adds native multipath support to the nvme driver. For each namespace we create only single block device node, which can be used to access that namespace through any of the controllers that refer to it. The gendisk for each controllers path to the name space still exists inside the kernel, but is hidden from userspace. The character device nodes are still available on a per-controller basis. A new link from the sysfs directory for the subsystem allows to find all controllers for a given subsystem. Currently we will always send I/O to the first available path, this will be changed once the NVMe Asynchronous Namespace Access (ANA) TP is ratified and implemented, at which point we will look at the ANA state for each namespace. Another possibility that was prototyped is to use the path that is closes to the submitting NUMA code, which will be mostly interesting for PCI, but might also be useful for RDMA or FC transports in the future. There is not plan to implement round robin or I/O service time path selectors, as those are not scalable with the performance rates provided by NVMe. The multipath device will go away once all paths to it disappear, any delay to keep it alive needs to be implemented at the controller level. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers/nvme/host/Kconfig')
-rw-r--r--drivers/nvme/host/Kconfig9
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/nvme/host/Kconfig b/drivers/nvme/host/Kconfig
index 46d6cb1e03bd..b979cf3bce65 100644
--- a/drivers/nvme/host/Kconfig
+++ b/drivers/nvme/host/Kconfig
@@ -13,6 +13,15 @@ config BLK_DEV_NVME
To compile this driver as a module, choose M here: the
module will be called nvme.
+config NVME_MULTIPATH
+ bool "NVMe multipath support"
+ depends on NVME_CORE
+ ---help---
+ This option enables support for multipath access to NVMe
+ subsystems. If this option is enabled only a single
+ /dev/nvmeXnY device will show up for each NVMe namespaces,
+ even if it is accessible through multiple controllers.
+
config NVME_FABRICS
tristate