• D
    libnvdimm, pmem, dax: export a cache control attribute · 6e0c90d6
    Dan Williams 提交于
    The dax_flush() operation can be turned into a nop on platforms where
    firmware arranges for cpu caches to be flushed on a power-fail event.
    The ACPI 6.2 specification defines a mechanism for the platform to
    indicate this capability so the kernel can select the proper default.
    However, for other platforms, the administrator must toggle this setting
    manually.
    
    Given this flush setting is a dax-specific mechanism we advertise it
    through a 'dax' attribute group hanging off a host device. For example,
    a 'pmem0' block-device gets a 'dax' sysfs-subdirectory with a
    'write_cache' attribute to control response to dax cache flush requests.
    This is similar to the 'queue/write_cache' attribute that appears under
    block devices.
    
    Cc: Jan Kara <jack@suse.cz>
    Cc: Jeff Moyer <jmoyer@redhat.com>
    Cc: Matthew Wilcox <mawilcox@microsoft.com>
    Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
    Suggested-by: NChristoph Hellwig <hch@lst.de>
    Signed-off-by: NDan Williams <dan.j.williams@intel.com>
    6e0c90d6
dax.h 5.0 KB