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authorDan Williams <dan.j.williams@intel.com>2018-05-16 11:46:08 -0700
committerDan Williams <dan.j.williams@intel.com>2018-05-22 06:59:39 -0700
commite7638488434415aa478e78435cac8f0365737638 (patch)
tree7ce50f0ed69889aa44cb0124451cf7a56b34eba6 /drivers/dax
parent5981690ddb8f72f9546a2d017a914cf56095fc1f (diff)
mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPS
In preparation for fixing dax-dma-vs-unmap issues, filesystems need to be able to rely on the fact that they will get wakeups on dev_pagemap page-idle events. Introduce MEMORY_DEVICE_FS_DAX and generic_dax_page_free() as common indicator / infrastructure for dax filesytems to require. With this change there are no users of the MEMORY_DEVICE_HOST designation, so remove it. The HMM sub-system extended dev_pagemap to arrange a callback when a dev_pagemap managed page is freed. Since a dev_pagemap page is free / idle when its reference count is 1 it requires an additional branch to check the page-type at put_page() time. Given put_page() is a hot-path we do not want to incur that check if HMM is not in use, so a static branch is used to avoid that overhead when not necessary. Now, the FS_DAX implementation wants to reuse this mechanism for receiving dev_pagemap ->page_free() callbacks. Rework the HMM-specific static-key into a generic mechanism that either HMM or FS_DAX code paths can enable. For ARCH=um builds, and any other arch that lacks ZONE_DEVICE support, care must be taken to compile out the DEV_PAGEMAP_OPS infrastructure. However, we still need to support FS_DAX in the FS_DAX_LIMITED case implemented by the s390/dcssblk driver. Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michal Hocko <mhocko@suse.com> Reported-by: kbuild test robot <lkp@intel.com> Reported-by: Thomas Meyer <thomas@m3y3r.de> Reported-by: Dave Jiang <dave.jiang@intel.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dax')
-rw-r--r--drivers/dax/super.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 2b2332b605e4..bf8bfaf5596f 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -86,6 +86,7 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
{
struct block_device *bdev = sb->s_bdev;
struct dax_device *dax_dev;
+ bool dax_enabled = false;
pgoff_t pgoff;
int err, id;
void *kaddr;
@@ -134,14 +135,21 @@ int __bdev_dax_supported(struct super_block *sb, int blocksize)
* on being able to do (page_address(pfn_to_page())).
*/
WARN_ON(IS_ENABLED(CONFIG_ARCH_HAS_PMEM_API));
+ dax_enabled = true;
} else if (pfn_t_devmap(pfn)) {
- /* pass */;
- } else {
+ struct dev_pagemap *pgmap;
+
+ pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
+ if (pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX)
+ dax_enabled = true;
+ put_dev_pagemap(pgmap);
+ }
+
+ if (!dax_enabled) {
pr_debug("VFS (%s): error: dax support not enabled\n",
sb->s_id);
return -EOPNOTSUPP;
}
-
return 0;
}
EXPORT_SYMBOL_GPL(__bdev_dax_supported);