kernel/linux.git/drivers/dax/pmem.c, branch v6.6.131

dax: Cleanup extra dax_region references

2023-06-23T07:03:50+00:00

Now that free_dev_dax_id() internally manages the references it needs the extra references taken by the dax_region drivers are not needed. Reported-by: Ira Weiny Signed-off-by: Dan Williams Link: https://lore.kernel.org/r/168577285161.1672036.8111253437794419696.stgit@dwillia2-xfh.jf.intel.com Reviewed-by: Dave Jiang Reviewed-by: Fan Ni Reviewed-by: Ira Weiny Signed-off-by: Vishal Verma

dax: Kill DEV_DAX_PMEM_COMPAT

2021-11-25T03:21:35+00:00

The /sys/class/dax compatibility option has shipped in the kernel for 4 years now which should be sufficient time for tools to abandon the old ABI in favor of the /sys/bus/dax device-model. Delete it now and see if anyone screams. Since this compatibility option shipped there has been more reports of users being surprised by the compat ABI than surprised by the "new", so the compat infrastructure has outlived its usefulness. Recall that /sys/bus/dax device-model is required for the dax kmem driver which allows PMEM to be used as "System RAM". The following projects were known to have a dependency on /sys/class/dax and have dropped their dependency as of the listed version: - ndctl (including libndctl, daxctl, and libdaxctl): v64+ - fio: v3.13+ - pmdk: v1.5.2+ As further evidence this option is no longer needed some distributions have already stopped enabling CONFIG_DEV_DAX_PMEM_COMPAT. Cc: Ira Weiny Cc: Dave Jiang Reported-by: Vishal Verma Acked-by: Dave Hansen Reviewed-by: Jane Chu Link: https://lore.kernel.org/r/163701116195.3784476.726128179293466337.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams

device-dax: Add /sys/class/dax backwards compatibility

2019-01-07T05:41:57+00:00

On the expectation that some environments may not upgrade libdaxctl (userspace component that depends on the /sys/class/dax hierarchy), provide a default / legacy dax_pmem_compat driver. The dax_pmem_compat driver implements the original /sys/class/dax sysfs layout rather than /sys/bus/dax. When userspace is upgraded it can blacklist this module and switch to the dax_pmem driver going forward. CONFIG_DEV_DAX_PMEM_COMPAT and supporting code will be deleted according to the dax_pmem entry in Documentation/ABI/obsolete/. Signed-off-by: Dan Williams

device-dax: Move resource pinning+mapping into the common driver

2019-01-07T05:26:21+00:00

Move the responsibility of calling devm_request_resource() and devm_memremap_pages() into the common device-dax driver. This is another preparatory step to allowing an alternate personality driver for a device-dax range. Signed-off-by: Dan Williams

device-dax: Start defining a dax bus model

2019-01-07T05:24:46+00:00

Towards eliminating the dax_class, move the dax-device-attribute enabling to a new bus.c file in the core. The amount of code thrash of sub-sequent patches is reduced as no logic changes are made, just pure code movement. A temporary export of unregister_dex_dax() and dax_attribute_groups is needed to preserve compilation, but those symbols become static again in a follow-on patch. Signed-off-by: Dan Williams

device-dax: Remove multi-resource infrastructure

2019-01-07T05:24:46+00:00

The multi-resource implementation anticipated discontiguous sub-division support. That has not yet materialized, delete the infrastructure and related code. Signed-off-by: Dan Williams

device-dax: Kill dax_region base

2019-01-07T05:24:46+00:00

Nothing consumes this attribute of a region and devres otherwise remembers the value for de-allocation purposes. Signed-off-by: Dan Williams

mm, devm_memremap_pages: fix shutdown handling

2018-12-28T20:11:47+00:00

The last step before devm_memremap_pages() returns success is to allocate a release action, devm_memremap_pages_release(), to tear the entire setup down. However, the result from devm_add_action() is not checked. Checking the error from devm_add_action() is not enough. The api currently relies on the fact that the percpu_ref it is using is killed by the time the devm_memremap_pages_release() is run. Rather than continue this awkward situation, offload the responsibility of killing the percpu_ref to devm_memremap_pages_release() directly. This allows devm_memremap_pages() to do the right thing relative to init failures and shutdown. Without this change we could fail to register the teardown of devm_memremap_pages(). The likelihood of hitting this failure is tiny as small memory allocations almost always succeed. However, the impact of the failure is large given any future reconfiguration, or disable/enable, of an nvdimm namespace will fail forever as subsequent calls to devm_memremap_pages() will fail to setup the pgmap_radix since there will be stale entries for the physical address range. An argument could be made to require that the ->kill() operation be set in the @pgmap arg rather than passed in separately. However, it helps code readability, tracking the lifetime of a given instance, to be able to grep the kill routine directly at the devm_memremap_pages() call site. Link: http://lkml.kernel.org/r/154275558526.76910.7535251937849268605.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Fixes: e8d513483300 ("memremap: change devm_memremap_pages interface...") Reviewed-by: "Jérôme Glisse" Reported-by: Logan Gunthorpe Reviewed-by: Logan Gunthorpe Reviewed-by: Christoph Hellwig Cc: Balbir Singh Cc: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

device-dax: avoid hang on error before devm_memremap_pages()

2018-08-01T00:05:42+00:00

dax_pmem_percpu_exit() waits for dax_pmem_percpu_release() to invoke the dax_pmem->cmp completion. Unfortunately this approach to cleaning up the percpu_ref only works after devm_memremap_pages() was successful. If devm_add_action_or_reset() or devm_memremap_pages() fails, dax_pmem_percpu_release() is not invoked. Therefore dax_pmem_percpu_exit() hangs waiting for the completion: rc = devm_add_action_or_reset(dev, dax_pmem_percpu_exit, &dax_pmem->ref); if (rc) return rc; dax_pmem->pgmap.ref = &dax_pmem->ref; addr = devm_memremap_pages(dev, &dax_pmem->pgmap); Avoid the hang by calling percpu_ref_exit() in the error paths instead of going through dax_pmem_percpu_exit(). Signed-off-by: Stefan Hajnoczi Signed-off-by: Dave Jiang

device-dax: use module_nd_driver

2018-03-15T14:18:47+00:00

Use module_nd_driver() instead of having module_init() and module_exit() callbacks which just call nd_driver_register() and nd_driver_unregister(). Signed-off-by: Johannes Thumshirn Signed-off-by: Dan Williams