One of the current shortcomings of the NVDIMM/PMEM support is that this memory does not have a page-struct(s) associated with its memory and therefor cannot be passed to a block-device or network or DMAed in any way through another device in the system.
The use of add_persistent_memory() fixes all this. After this patch an FS can do: bdev_direct_access(,&pfn,); page = pfn_to_page(pfn); And use that page for a lock_page(), set_page_dirty(), and/or anything else one might do with a page *. (Note that with brd one can already do this) [pmem-pages-ref-count] pmem will serve it's pages with ref==0. Once an FS does an blkdev_get_XXX(,FMODE_EXCL,), that memory is own by the FS. The FS needs to manage its allocation, just as it already does for its disk blocks. The fs should set page->count = 2, before submission to any Kernel subsystem so when it returns it will never be released to the Kernel's page-allocators. (page_freeze) Signed-off-by: Boaz Harrosh <b...@plexistor.com> --- drivers/block/Kconfig | 13 +++++++++++++ drivers/block/pmem.c | 20 ++++++++++++++++++++ 2 files changed, 33 insertions(+) diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig index 1530c2a..635fa6a 100644 --- a/drivers/block/Kconfig +++ b/drivers/block/Kconfig @@ -422,6 +422,19 @@ config BLK_DEV_PMEM Most normal users won't need this functionality, and can thus say N here. +config BLK_DEV_PMEM_USE_PAGES + bool "Enable use of page struct pages with pmem" + depends on BLK_DEV_PMEM + depends on PERSISTENT_MEMORY_DEPENDENCY + select DRIVER_NEEDS_PERSISTENT_MEMORY + default y + help + If a user of PMEM device needs "struct page" associated + with its memory, so this memory can be sent to other + block devices, or sent on the network, or be DMA transferred + to other devices in the system, then you must say "Yes" here. + If unsure leave as Yes. + config CDROM_PKTCDVD tristate "Packet writing on CD/DVD media" depends on !UML diff --git a/drivers/block/pmem.c b/drivers/block/pmem.c index f0f0ba0..d0c80f4 100644 --- a/drivers/block/pmem.c +++ b/drivers/block/pmem.c @@ -20,6 +20,7 @@ #include <linux/blkdev.h> #include <linux/hdreg.h> #include <linux/init.h> +#include <linux/memory_hotplug.h> #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/slab.h> @@ -141,6 +142,24 @@ MODULE_PARM_DESC(map, static LIST_HEAD(pmem_devices); +#ifdef CONFIG_BLK_DEV_PMEM_USE_PAGES +/* pmem->phys_addr and pmem->size need to be set. + * Will then set pmem->virt_addr if successful. + */ +int pmem_mapmem(struct pmem_device *pmem) +{ + return add_persistent_memory(pmem->phys_addr, pmem->size, + &pmem->virt_addr); +} + +static void pmem_unmapmem(struct pmem_device *pmem) +{ + remove_persistent_memory(pmem->phys_addr, pmem->size); +} + +#define PMEM_ALIGNMEM (1UL << SECTION_SIZE_BITS) +#else /* !CONFIG_BLK_DEV_PMEM_USE_PAGES */ + /* pmem->phys_addr and pmem->size need to be set. * Will then set virt_addr if successful. */ @@ -180,6 +199,7 @@ void pmem_unmapmem(struct pmem_device *pmem) } #define PMEM_ALIGNMEM PAGE_SIZE +#endif /* ! CONFIG_BLK_DEV_PMEM_USE_PAGES */ static struct pmem_device *pmem_alloc(phys_addr_t phys_addr, size_t disk_size, int i) -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/