dax: remove the pgmap sanity checks in generic_fsdax_supported

Drivers that register a dax_dev should make sure it works, no need
to double check from the file system.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20211129102203.2243509-6-hch@lst.de
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index bf77c3d..c8500b7 100644 (file)
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -106,13 +106,9 @@ bool generic_fsdax_supported(struct dax_device *dax_dev,
                struct block_device *bdev, int blocksize, sector_t start,
                sector_t sectors)
 {
-       bool dax_enabled = false;
        pgoff_t pgoff, pgoff_end;
-       void *kaddr, *end_kaddr;
-       pfn_t pfn, end_pfn;
        sector_t last_page;
-       long len, len2;
-       int err, id;
+       int err;
 
        if (blocksize != PAGE_SIZE) {
                pr_info("%pg: error: unsupported blocksize for dax\n", bdev);
@@ -137,49 +133,6 @@ bool generic_fsdax_supported(struct dax_device *dax_dev,
                return false;
        }
 
-       id = dax_read_lock();
-       len = dax_direct_access(dax_dev, pgoff, 1, &kaddr, &pfn);
-       len2 = dax_direct_access(dax_dev, pgoff_end, 1, &end_kaddr, &end_pfn);
-
-       if (len < 1 || len2 < 1) {
-               pr_info("%pg: error: dax access failed (%ld)\n",
-                               bdev, len < 1 ? len : len2);
-               dax_read_unlock(id);
-               return false;
-       }
-
-       if (IS_ENABLED(CONFIG_FS_DAX_LIMITED) && pfn_t_special(pfn)) {
-               /*
-                * An arch that has enabled the pmem api should also
-                * have its drivers support pfn_t_devmap()
-                *
-                * This is a developer warning and should not trigger in
-                * production. dax_flush() will crash since it depends
-                * 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) && pfn_t_devmap(end_pfn)) {
-               struct dev_pagemap *pgmap, *end_pgmap;
-
-               pgmap = get_dev_pagemap(pfn_t_to_pfn(pfn), NULL);
-               end_pgmap = get_dev_pagemap(pfn_t_to_pfn(end_pfn), NULL);
-               if (pgmap && pgmap == end_pgmap && pgmap->type == MEMORY_DEVICE_FS_DAX
-                               && pfn_t_to_page(pfn)->pgmap == pgmap
-                               && pfn_t_to_page(end_pfn)->pgmap == pgmap
-                               && pfn_t_to_pfn(pfn) == PHYS_PFN(__pa(kaddr))
-                               && pfn_t_to_pfn(end_pfn) == PHYS_PFN(__pa(end_kaddr)))
-                       dax_enabled = true;
-               put_dev_pagemap(pgmap);
-               put_dev_pagemap(end_pgmap);
-
-       }
-       dax_read_unlock(id);
-
-       if (!dax_enabled) {
-               pr_info("%pg: error: dax support not enabled\n", bdev);
-               return false;
-       }
        return true;
 }
 EXPORT_SYMBOL_GPL(generic_fsdax_supported);