Merge tag 'libnvdimm-for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm updates from Ross Zwisler:

 - Require struct page by default for filesystem DAX to remove a number
   of surprising failure cases. This includes failures with direct I/O,
   gdb and fork(2).

 - Add support for the new Platform Capabilities Structure added to the
   NFIT in ACPI 6.2a. This new table tells us whether the platform
   supports flushing of CPU and memory controller caches on unexpected
   power loss events.

 - Revamp vmem_altmap and dev_pagemap handling to clean up code and
   better support future future PCI P2P uses.

 - Deprecate the ND_IOCTL_SMART_THRESHOLD command whose payload has
   become out-of-sync with recent versions of the NVDIMM_FAMILY_INTEL
   spec, and instead rely on the generic ND_CMD_CALL approach used by
   the two other IOCTL families, NVDIMM_FAMILY_{HPE,MSFT}.

 - Enhance nfit_test so we can test some of the new things added in
   version 1.6 of the DSM specification. This includes testing firmware
   download and simulating the Last Shutdown State (LSS) status.

* tag 'libnvdimm-for-4.16' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (37 commits)
  libnvdimm, namespace: remove redundant initialization of 'nd_mapping'
  acpi, nfit: fix register dimm error handling
  libnvdimm, namespace: make min namespace size 4K
  tools/testing/nvdimm: force nfit_test to depend on instrumented modules
  libnvdimm/nfit_test: adding support for unit testing enable LSS status
  libnvdimm/nfit_test: add firmware download emulation
  nfit-test: Add platform cap support from ACPI 6.2a to test
  libnvdimm: expose platform persistence attribute for nd_region
  acpi: nfit: add persistent memory control flag for nd_region
  acpi: nfit: Add support for detect platform CPU cache flush on power loss
  device-dax: Fix trailing semicolon
  libnvdimm, btt: fix uninitialized err_lock
  dax: require 'struct page' by default for filesystem dax
  ext2: auto disable dax instead of failing mount
  ext4: auto disable dax instead of failing mount
  mm, dax: introduce pfn_t_special()
  mm: Fix devm_memremap_pages() collision handling
  mm: Fix memory size alignment in devm_memremap_pages_release()
  memremap: merge find_dev_pagemap into get_dev_pagemap
  memremap: change devm_memremap_pages interface to use struct dev_pagemap
  ...

3 files changed, 18 insertions, 5 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index 9774588da60e..bc821a86d965 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -58,6 +58,13 @@ config FS_DAX_PMD
 	depends on ZONE_DEVICE
 	depends on TRANSPARENT_HUGEPAGE
 
+# Selected by DAX drivers that do not expect filesystem DAX to support
+# get_user_pages() of DAX mappings. I.e. "limited" indicates no support
+# for fork() of processes with MAP_SHARED mappings or support for
+# direct-I/O to a DAX mapping.
+config FS_DAX_LIMITED
+	bool
+
 endif # BLOCK
 
 # Posix ACL utility routines
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index db5f9daa7780..0a638e79bf7c 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -962,8 +962,11 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 
 	if (sbi->s_mount_opt & EXT2_MOUNT_DAX) {
 		err = bdev_dax_supported(sb, blocksize);
-		if (err)
-			goto failed_mount;
+		if (err) {
+			ext2_msg(sb, KERN_ERR,
+				"DAX unsupported by block device. Turning off DAX.");
+			sbi->s_mount_opt &= ~EXT2_MOUNT_DAX;
+		}
 	}
 
 	/* If the blocksize doesn't match, re-read the thing.. */
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 421222ec3509..39bf464c35f1 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3712,11 +3712,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 		if (ext4_has_feature_inline_data(sb)) {
 			ext4_msg(sb, KERN_ERR, "Cannot use DAX on a filesystem"
 					" that may contain inline data");
-			goto failed_mount;
+			sbi->s_mount_opt &= ~EXT4_MOUNT_DAX;
 		}
 		err = bdev_dax_supported(sb, blocksize);
-		if (err)
-			goto failed_mount;
+		if (err) {
+			ext4_msg(sb, KERN_ERR,
+				"DAX unsupported by block device. Turning off DAX.");
+			sbi->s_mount_opt &= ~EXT4_MOUNT_DAX;
+		}
 	}
 
 	if (ext4_has_feature_encrypt(sb) && es->s_encryption_level) {