From 0aefa05420c0e81eec2496b28a1b5d6e7783cb23 Mon Sep 17 00:00:00 2001 From: Vishal Verma Date: Fri, 27 May 2016 12:43:45 -0600 Subject: [PATCH] libnvdimm, btt: update the usage section in Documentation Section 5 about BTT's in kernel usage was quite obsolete, replace it with a simple 'Usage' section that describes how to set up a BTT namespace using the 'ndctl' utility. Signed-off-by: Vishal Verma Signed-off-by: Dan Williams --- Documentation/nvdimm/btt.txt | 28 +++++++++------------------- 1 file changed, 9 insertions(+), 19 deletions(-) diff --git a/Documentation/nvdimm/btt.txt b/Documentation/nvdimm/btt.txt index b91443f577dc..e293fb664924 100644 --- a/Documentation/nvdimm/btt.txt +++ b/Documentation/nvdimm/btt.txt @@ -256,28 +256,18 @@ If any of these error conditions are encountered, the arena is put into a read only state using a flag in the info block. -5. In-kernel usage -================== +5. Usage +======== -Any block driver that supports byte granularity IO to the storage may register -with the BTT. It will have to provide the rw_bytes interface in its -block_device_operations struct: +The BTT can be set up on any disk (namespace) exposed by the libnvdimm subsystem +(pmem, or blk mode). The easiest way to set up such a namespace is using the +'ndctl' utility [1]: - int (*rw_bytes)(struct gendisk *, void *, size_t, off_t, int rw); +For example, the ndctl command line to setup a btt with a 4k sector size is: -It may register with the BTT after it adds its own gendisk, using btt_init: + ndctl create-namespace -f -e namespace0.0 -m sector -l 4k - struct btt *btt_init(struct gendisk *disk, unsigned long long rawsize, - u32 lbasize, u8 uuid[], int maxlane); +See ndctl create-namespace --help for more options. -note that maxlane is the maximum amount of concurrency the driver wishes to -allow the BTT to use. - -The BTT 'disk' appears as a stacked block device that grabs the underlying block -device in the O_EXCL mode. - -When the driver wishes to remove the backing disk, it should similarly call -btt_fini using the same struct btt* handle that was provided to it by btt_init. - - void btt_fini(struct btt *btt); +[1]: https://github.com/pmem/ndctl -- GitLab