[ndctl PATCH 1/4] ndctl, create-namespace: fix --map= reconfiguration for device-dax

[ndctl PATCH 1/4] ndctl, create-namespace: fix --map= reconfiguration for device-dax

[Dan Williams]

Allow the memmap location to be changed when reconfiguring a device-dax
mode namespace.

Fixes: 3139dfda1158 ("ndctl: create namespace")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 ndctl/namespace.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ndctl/namespace.c b/ndctl/namespace.c
index 58f23ad0877a..0020be354670 100644
--- a/ndctl/namespace.c
+++ b/ndctl/namespace.c
@@ -198,7 +198,8 @@ static int set_defaults(enum device_action mode)
 		}
 
 		if (!param.reconfig && param.mode
-				&& strcmp(param.mode, "memory") != 0) {
+				&& strcmp(param.mode, "memory") != 0
+				&& strcmp(param.mode, "dax") != 0) {
 			error("--map only valid for a memory mode pmem namespace\n");
 			rc = -EINVAL;
 		}

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[ndctl PATCH 2/4] ndctl, create-namespace: catch attempts to set device-dax for blk namespaces

[Dan Williams]

Similar to the filesytem-dax case blk type namespaces do not support
device-dax operation.

Fixes: 3139dfda1158 ("ndctl: create namespace")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 ndctl/namespace.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/ndctl/namespace.c b/ndctl/namespace.c
index 0020be354670..970515570ce9 100644
--- a/ndctl/namespace.c
+++ b/ndctl/namespace.c
@@ -208,8 +208,9 @@ static int set_defaults(enum device_action mode)
 
 	/* check for incompatible mode and type combinations */
 	if (param.type && param.mode && strcmp(param.type, "blk") == 0
-			&& strcmp(param.mode, "memory") == 0) {
-		error("only 'pmem' namespaces can be placed into 'memory' mode\n");
+			&& (strcmp(param.mode, "memory") == 0
+				|| strcmp(param.mode, "dax") == 0)) {
+		error("only 'pmem' namespaces support dax operation\n");
 		rc = -ENXIO;
 	}
 

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[ndctl PATCH 3/4] ndctl, create-namespace: introduce "fsdax" and "devdax" modes

[Dan Williams]

In hindsight "memory" was terrible name for the mode that supports a
'struct page' allocation/reservation to support filesystem-dax
operation. Now that the kernel is moving to disable "page-less" dax we
can just name this mode "fsdax" directly. The "dax" mode name is also
ambiguous so we rename it to "devdax".

The old names are still accepted as options and "ndctl listr" will only use
the new names when the --human option is specified so that scripts that
have learned the original names do not break.

The man page is refreshed to address user questions around what the
modes imply for system operation.

Reported-by: Kelly Couch <kelly.j.couch@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 Documentation/ndctl/ndctl-create-namespace.txt |   98 ++++++++++++++----------
 contrib/ndctl                                  |    2 
 ndctl/libndctl.h.in                            |    2 
 ndctl/namespace.c                              |    8 +-
 util/json.c                                    |   10 ++
 5 files changed, 75 insertions(+), 45 deletions(-)

diff --git a/Documentation/ndctl/ndctl-create-namespace.txt b/Documentation/ndctl/ndctl-create-namespace.txt
index 4f1f9849207f..0910edd753ab 100644
--- a/Documentation/ndctl/ndctl-create-namespace.txt
+++ b/Documentation/ndctl/ndctl-create-namespace.txt
@@ -15,7 +15,8 @@ include::namespace-description.txt[]
 EXAMPLES
 --------
 
-Create a maximally sized pmem namespace in 'memory' mode
+Create a maximally sized pmem namespace in 'fsdax' mode (the
+default)
 [verse]
 ndctl create-namespace
 
@@ -28,24 +29,26 @@ OPTIONS
 -t::
 --type=::
 	Create a 'pmem' or 'blk' namespace (subject to available
-	capacity).  A pmem namespace supports the DAX (direct access)
+	capacity).  A pmem namespace supports the dax (direct access)
 	capability to linkndctl:mmap[2] persistent memory directly into
 	a process address space.  A blk namespace access persistent
 	memory through a block-window-aperture.  Compared to pmem it
 	supports a traditional storage error model (EIO on error rather
 	than a cpu exception on a bad memory access), but it does not
-	support DAX.
+	support dax.
 
 -m::
 --mode=::
-	- "raw": expose the namespace capacity directly with some
-	  limitations.  Neither a raw pmem namepace nor raw blk namespace
-	  support sector atomicity by default (see "sector" mode below).  A
-	  raw pmem namespace may have limited support for passing a DAX
-	  mapping to other syscalls.  I.e. direct-I/O to/from a DAX buffer
-	  may fail for a pmem namespace in raw mode.
-
-	- "sector" or "safe": persistent memory, given that it is byte
+	- "raw": expose the namespace capacity directly with
+	  limitations.  Neither a raw pmem namepace nor raw blk
+	  namespace support sector atomicity by default (see "sector"
+	  mode below).  A raw pmem namespace may have limited to no dax
+	  support depending the kernel. In other words operations like
+	  direct-I/O targeting a dax buffer may fail for a pmem
+	  namespace in raw mode or indirect through a page-cache buffer.
+	  See "fsdax" and "devdax" mode for dax operation.
+
+	- "sector": persistent memory, given that it is byte
 	  addressable, does not support sector atomicity.  The
 	  problematic aspect of sector tearing is that most applications
 	  do not know they have a atomic sector update dependency.  At
@@ -54,27 +57,34 @@ OPTIONS
 	  Persistent memory devices will always tear and always
 	  silently.  Until an application is audited to be robust in the
 	  presence of sector-tearing "safe" mode is recommended.  This
-	  imposes some performance overhead and disables the DAX
-	  capability.
-
-	- "memory": A pmem namespace in this mode supports direct I/O
-	  to/from DAX mappings.  Depending on the kernel this mode may
-	  come at the cost of allocating per-pmem-page metadata.  If that
-	  allocation is required the capacity can be allocated from
-	  "System RAM" or from a reserved portion of pmem (see the --map=
-	  option).
-
-	- "dax": Device DAX is the device-centric analogue of Filesystem
-	  DAX (CONFIG_FS_DAX).  It allows memory ranges to be allocated
-	  and mapped without need of an intervening file system.  Device
-	  DAX is strict, precise and predictable.  Specifically this
-	  interface:
+	  imposes some performance overhead and disables the dax
+	  capability. (also known as "safe" or "btt" mode)
+
+	- "fsdax": A pmem namespace in this mode supports dax
+	  operation with a block-device based filesystem (in previous
+	  ndctl releases this mode was named "memory" mode). This mode
+	  comes at the cost of allocating per-page metadata. The
+	  capacity can be allocated from "System RAM", or from a
+	  reserved portion of "Persistent Memory" (see the --map=
+	  option).  Note that a filesystem is required for dax
+	  operation, the resulting raw block device (/dev/pmemX) will
+	  use the page cache. See "devdax" mode for raw device access
+	  that supports dax.
+
+	- "devdax": The device-dax character device interface is a
+	  statically allocated / raw access analogue of filesystem-dax
+	  (in previous ndctl releases this mode was named "dax" mode).
+	  It allows memory ranges to be mapped without need of an
+	  intervening filesystem.  The device-dax is interface strict,
+	  precise and predictable. Specifically the interface:
 
 	  * Guarantees fault granularity with respect to a given page
-	    size (pte, pmd, or pud) set at configuration time.
+	    size (4K, 2M, or 1G on x86) set at configuration time.
 
 	  * Enforces deterministic behavior by being strict about what
-	    fault scenarios are supported.
+	    fault scenarios are supported. I.e. if a device is
+	    configured with a 2M alignment an attempt to fault a 4K
+	    aligned offset will result in SIGBUS.
 
 -s::
 --size=::
@@ -90,12 +100,16 @@ OPTIONS
 
 -a::
 --align::
-	Applications that want to establish DAX memory mappings
-	with page table entries greater than 4K in size need a
-	persistent memory namespace that is sufficiently aligned. For
-	"memory" and "dax" mode this defaults to 2M. Note that "dax"
-	mode enforces all mappings to be aligned to this value,
-	i.e. fails unaligned mapping attempts.
+	Applications that want to establish dax memory mappings with
+	page table entries greater than system base page size (4K on
+	x86) need a persistent memory namespace that is sufficiently
+	aligned. For "fsdax" and "devdax" mode this defaults to 2M.
+	Note that "devdax" mode enforces all mappings to be aligned to
+	this value, i.e. it fails unaligned mapping attempts. The
+	"fsdax" alignment setting determines the starting alignment of
+	filesystem extents and may limit the possible granularities,
+	if a large mapping is not possible it will silently fall back
+	to a smaller page size.
 
 -e::
 --reconfig=::
@@ -116,21 +130,25 @@ OPTIONS
 --name=::
 	For NVDIMM devices that support namespace labels,
 	specify a human friendly name for a namespace.  This name is
-	available as device attribute for use in udev rules or
-	elsewhere.
+	available as a device attribute for use in udev rules.
 
 -l::
 --sector-size::
-	Specify the logical sector size (LBA size) of the block storage
-	device associated with a namespace.
+	Specify the logical sector size (LBA size) of the
+	Linux block device associated with an namespace.
 
 -M::
 --map=::
-	A pmem namespace in "memory" mode may require allocation
-	of per-page metadata.  The allocation can be drawn from either:
+	A pmem namespace in "fsdax" or "devdax" mode requires allocation of
+	per-page metadata.  The allocation can be drawn from either:
 	- "mem": typical system memory
 	- "dev": persistent memory reserved from the namespace
 
+	Given relative capacities of "Persistent Memory" to "System
+	RAM" the allocation defaults to reserving space out of the
+	namespace directly ("--map=dev"). The overhead is 64-bytes per
+	4K (16GB per 1TB) on x86.
+
 -f::
 --force::
 	Unless this option is specified the 'reconfigure namespace'
diff --git a/contrib/ndctl b/contrib/ndctl
index 86718eb4fa4a..d98386807769 100755
--- a/contrib/ndctl
+++ b/contrib/ndctl
@@ -188,7 +188,7 @@ __ndctl_comp_options()
 			fi
 			;;
 		--mode)
-			opts="raw sector memory dax"
+			opts="raw sector fsdax devdax memory dax"
 			if [[ "$type_filter" == "blk" ]]; then
 				opts="raw sector"
 			fi
diff --git a/ndctl/libndctl.h.in b/ndctl/libndctl.h.in
index a42a7a4105b9..fb77d243a893 100644
--- a/ndctl/libndctl.h.in
+++ b/ndctl/libndctl.h.in
@@ -511,9 +511,11 @@ const char *ndctl_namespace_get_type_name(struct ndctl_namespace *ndns);
 const char *ndctl_namespace_get_block_device(struct ndctl_namespace *ndns);
 enum ndctl_namespace_mode {
 	NDCTL_NS_MODE_MEMORY,
+	NDCTL_NS_MODE_FSDAX = NDCTL_NS_MODE_MEMORY,
 	NDCTL_NS_MODE_SAFE,
 	NDCTL_NS_MODE_RAW,
 	NDCTL_NS_MODE_DAX,
+	NDCTL_NS_MODE_DEVDAX = NDCTL_NS_MODE_DAX,
 	NDCTL_NS_MODE_UNKNOWN, /* must be last entry */
 };
 enum ndctl_namespace_mode ndctl_namespace_get_mode(
diff --git a/ndctl/namespace.c b/ndctl/namespace.c
index 970515570ce9..d31244b71c37 100644
--- a/ndctl/namespace.c
+++ b/ndctl/namespace.c
@@ -171,10 +171,14 @@ static int set_defaults(enum device_action mode)
 		      param.mode = "safe"; /* pass */
 		else if (strcmp(param.mode, "memory") == 0)
 		      /* pass */;
+		else if (strcmp(param.mode, "fsdax") == 0)
+			param.mode = "memory"; /* pass */
 		else if (strcmp(param.mode, "raw") == 0)
 		      /* pass */;
 		else if (strcmp(param.mode, "dax") == 0)
 		      /* pass */;
+		else if (strcmp(param.mode, "devdax") == 0)
+			param.mode = "dax"; /* pass */
 		else {
 			error("invalid mode '%s'\n", param.mode);
 			rc = -EINVAL;
@@ -200,7 +204,7 @@ static int set_defaults(enum device_action mode)
 		if (!param.reconfig && param.mode
 				&& strcmp(param.mode, "memory") != 0
 				&& strcmp(param.mode, "dax") != 0) {
-			error("--map only valid for a memory mode pmem namespace\n");
+			error("--map only valid for an dax mode pmem namespace\n");
 			rc = -EINVAL;
 		}
 	} else if (!param.reconfig)
@@ -514,7 +518,7 @@ static int validate_namespace_options(struct ndctl_region *region,
 					|| p->mode == NDCTL_NS_MODE_DAX)) {
 			debug("blk %s does not support %s mode\n", region_name,
 					p->mode == NDCTL_NS_MODE_MEMORY
-					? "memory" : "dax");
+					? "fsdax" : "devdax");
 			return -EAGAIN;
 		}
 	} else if (ndns)
diff --git a/util/json.c b/util/json.c
index 02a4e93d48b4..f49921236823 100644
--- a/util/json.c
+++ b/util/json.c
@@ -679,13 +679,19 @@ struct json_object *util_namespace_to_json(struct ndctl_namespace *ndns,
 			size = ndctl_pfn_get_size(pfn);
 		else /* native/static memory mode */
 			size = ndctl_namespace_get_size(ndns);
-		jobj = json_object_new_string("memory");
+		if (flags & UTIL_JSON_HUMAN)
+			jobj = json_object_new_string("fsdax");
+		else
+			jobj = json_object_new_string("memory");
 		break;
 	case NDCTL_NS_MODE_DAX:
 		if (!dax)
 			goto err;
 		size = ndctl_dax_get_size(dax);
-		jobj = json_object_new_string("dax");
+		if (flags & UTIL_JSON_HUMAN)
+			jobj = json_object_new_string("devdax");
+		else
+			jobj = json_object_new_string("dax");
 		break;
 	case NDCTL_NS_MODE_SAFE:
 		if (!btt)

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[ndctl PATCH 4/4] ndctl, create-namespace: document autolabel operation

[Dan Williams]

Write up how the autolabel mechanism operates, when it is used, and what
to do when it fails.

Reported-by: Kelly Couch <kelly.j.couch@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 Documentation/ndctl/ndctl-check-labels.txt     |    3 +-
 Documentation/ndctl/ndctl-check-namespace.txt  |    3 +-
 Documentation/ndctl/ndctl-create-namespace.txt |   47 +++++++++++++++++++++++-
 Documentation/ndctl/ndctl-init-labels.txt      |    4 +-
 Documentation/ndctl/ndctl-read-labels.txt      |    3 +-
 Documentation/ndctl/ndctl-write-labels.txt     |    3 +-
 Documentation/ndctl/ndctl-zero-labels.txt      |    3 +-
 7 files changed, 52 insertions(+), 14 deletions(-)

diff --git a/Documentation/ndctl/ndctl-check-labels.txt b/Documentation/ndctl/ndctl-check-labels.txt
index 210eb23caf66..a7c8a5f2dcbd 100644
--- a/Documentation/ndctl/ndctl-check-labels.txt
+++ b/Documentation/ndctl/ndctl-check-labels.txt
@@ -28,5 +28,4 @@ the extent permitted by law.
 
 SEE ALSO
 --------
-http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf[NVDIMM Namespace
-Specification]
+http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf[UEFI NVDIMM Label Protocol]
diff --git a/Documentation/ndctl/ndctl-check-namespace.txt b/Documentation/ndctl/ndctl-check-namespace.txt
index 07fe15ac5485..49353b1b217f 100644
--- a/Documentation/ndctl/ndctl-check-namespace.txt
+++ b/Documentation/ndctl/ndctl-check-namespace.txt
@@ -67,5 +67,4 @@ SEE ALSO
 --------
 linkndctl:ndctl-disable-namespace[1],
 linkndctl:ndctl-enable-namespace[1],
-http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf[NVDIMM Namespace
-Specification]
+http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf[UEFI NVDIMM Label Protocol]
diff --git a/Documentation/ndctl/ndctl-create-namespace.txt b/Documentation/ndctl/ndctl-create-namespace.txt
index 0910edd753ab..c8b1c99c5229 100644
--- a/Documentation/ndctl/ndctl-create-namespace.txt
+++ b/Documentation/ndctl/ndctl-create-namespace.txt
@@ -159,6 +159,48 @@ OPTIONS
 	namespace' operations will be aborted.  The namespace must be
 	unmounted before being reconfigured.
 
+-L::
+--autolabel::
+--no-autolabel::
+	Legacy NVDIMM devices do not support namespace labels. In that
+	case the kernel creates region-sized namespaces that can not
+	be deleted.  Their mode can be changed, but they can not be
+	resized smaller than their parent region. This is termed a
+	"label-less namespace". In contrast, NVDIMMs and hypervisors
+	that support the ACPI 6.2 label area definition (ACPI 6.2
+	Section 6.5.10 NVDIMM Label Methods) support "labelled
+	namespace" operation.
+
+	There are two cases where the kernel will default to
+	label-less operation:
+
+	* NVDIMM does not support labels
+
+	* The NVDIMM supports labels, but the Label Index Block (see
+	  UEFI 2.7) is not present and there is no capacity aliasing
+	  between 'blk' and 'pmem' regions.
+
+	In the latter case the configuration can be upgraded to
+	labelled operation by writing an index block on all DIMMs in a
+	region and re-enabling that region. The 'autolabel' capability
+	of 'ndctl create-namespace --reconfig' tries to do this by
+	default if it can determine that all DIMM capacity is
+	referenced by the namespace being reconfigured. It will
+	otherwise fail to autolabel and remain in label-less mode if
+	it finds a DIMM contributes capacity to more than one region.
+	This check prevents inadvertent data loss of that other region
+	is in active use. The --autolabel option is implied by
+	default, the --no-autolabel option can be used to disable this
+	behavior. When automatic labeling fails and labelled operation
+	is still desired the safety policy can be bypassed by the
+	following commands, note that all data on all regions is
+	forfeited by running these commands:
+
+	[verse]
+	ndctl disable-region all
+	ndctl init-labels all
+	ndctl enable-region all
+
 -v::
 --verbose::
 	Emit debug messages for the namespace creation process
@@ -177,7 +219,8 @@ the extent permitted by law.
 SEE ALSO
 --------
 linkndctl:ndctl-zero-labels[1],
+linkndctl:ndctl-init-labels[1],
 linkndctl:ndctl-disable-namespace[1],
 linkndctl:ndctl-enable-namespace[1],
-http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf[NVDIMM Namespace
-Specification]
+http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf[UEFI NVDIMM Label Protocol
+]
diff --git a/Documentation/ndctl/ndctl-init-labels.txt b/Documentation/ndctl/ndctl-init-labels.txt
index a5c0c127e279..d30ccc5fed0d 100644
--- a/Documentation/ndctl/ndctl-init-labels.txt
+++ b/Documentation/ndctl/ndctl-init-labels.txt
@@ -85,5 +85,5 @@ the extent permitted by law.
 
 SEE ALSO
 --------
-http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf[NVDIMM Namespace
-Specification]
+linkndctl:ndctl-create-namespace[1],
+http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf[UEFI NVDIMM Label Protocol]
diff --git a/Documentation/ndctl/ndctl-read-labels.txt b/Documentation/ndctl/ndctl-read-labels.txt
index a1640d6ff566..a15e0f1061d6 100644
--- a/Documentation/ndctl/ndctl-read-labels.txt
+++ b/Documentation/ndctl/ndctl-read-labels.txt
@@ -34,5 +34,4 @@ the extent permitted by law.
 
 SEE ALSO
 --------
-http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf[NVDIMM Namespace
-Specification]
+http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf[UEFI NVDIMM Label Protocol]
diff --git a/Documentation/ndctl/ndctl-write-labels.txt b/Documentation/ndctl/ndctl-write-labels.txt
index bace46fba160..5e54cece95ca 100644
--- a/Documentation/ndctl/ndctl-write-labels.txt
+++ b/Documentation/ndctl/ndctl-write-labels.txt
@@ -25,5 +25,4 @@ include::labels-options.txt[]
 
 SEE ALSO
 --------
-http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf[NVDIMM Namespace
-Specification]
+http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf[UEFI NVDIMM Label Protocol]
diff --git a/Documentation/ndctl/ndctl-zero-labels.txt b/Documentation/ndctl/ndctl-zero-labels.txt
index 56dacf1c1714..4d56696b1933 100644
--- a/Documentation/ndctl/ndctl-zero-labels.txt
+++ b/Documentation/ndctl/ndctl-zero-labels.txt
@@ -27,5 +27,4 @@ the extent permitted by law.
 
 SEE ALSO
 --------
-http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf[NVDIMM Namespace
-Specification]
+http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf[UEFI NVDIMM Label Protocol]

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