[PATCH 1/4] libndctl: Use the supported_alignment attribute

[Oliver O'Halloran <oohall@gmail.com>]

Newer kernels provide the "supported_alignments" sysfs attribute that
indicates what alignments can be used with a PFN or DAX namespace. This
patch adds the plumbing inside of libndctl to allow users to query this
information through using:
	ndctl_{dax|pfn}_get_supported_alignment(), and
	ndctl_{dax|pfn}_get_num_alignments()

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
---
 ndctl/lib/libndctl.c   | 40 ++++++++++++++++++++++++++++++++++++++++
 ndctl/lib/libndctl.sym |  7 +++++++
 ndctl/libndctl.h       |  6 ++++++
 3 files changed, 53 insertions(+)

diff --git a/ndctl/lib/libndctl.c b/ndctl/lib/libndctl.c
index 0c3a35e5bcc9..4d0e58a22953 100644
--- a/ndctl/lib/libndctl.c
+++ b/ndctl/lib/libndctl.c
@@ -31,6 +31,7 @@
 #include <ccan/build_assert/build_assert.h>
 
 #include <ndctl.h>
+#include <util/size.h>
 #include <util/sysfs.h>
 #include <ndctl/libndctl.h>
 #include <ndctl/namespace.h>
@@ -237,6 +238,7 @@ struct ndctl_pfn {
 	int buf_len;
 	uuid_t uuid;
 	int id, generation;
+	struct ndctl_lbasize alignments;
 };
 
 struct ndctl_dax {
@@ -4781,6 +4783,18 @@ static void *__add_pfn(struct ndctl_pfn *pfn, const char *pfn_base)
 	else
 		pfn->size = strtoull(buf, NULL, 0);
 
+	/*
+	 * If the kernel doesn't provide the supported_alignments sysfs
+	 * attribute then it's safe to assume that we are running on x86
+	 * which will always support 2MB and 4KB alignments.
+	 */
+	sprintf(path, "%s/supported_alignments", pfn_base);
+	if (sysfs_read_attr(ctx, path, buf) < 0)
+		sprintf(buf, "%d %d", SZ_4K, SZ_2M);
+
+	if (parse_lbasize_supported(ctx, pfn_base, buf, &pfn->alignments) < 0)
+		goto err_read;
+
 	free(path);
 	return pfn;
 
@@ -5015,6 +5029,22 @@ NDCTL_EXPORT int ndctl_pfn_set_align(struct ndctl_pfn *pfn, unsigned long align)
 	return 0;
 }
 
+NDCTL_EXPORT unsigned int ndctl_pfn_get_num_alignments(struct ndctl_pfn *pfn)
+{
+	return pfn->alignments.num;
+}
+
+NDCTL_EXPORT int ndctl_pfn_get_supported_alignment(struct ndctl_pfn *pfn, int i)
+{
+	if (pfn->alignments.num == 0)
+		return 0;
+
+	if (i < 0 || i > pfn->alignments.num)
+		return UINT_MAX;
+	else
+		return pfn->alignments.supported[i];
+}
+
 NDCTL_EXPORT int ndctl_pfn_set_namespace(struct ndctl_pfn *pfn,
 		struct ndctl_namespace *ndns)
 {
@@ -5237,6 +5267,16 @@ NDCTL_EXPORT unsigned long ndctl_dax_get_align(struct ndctl_dax *dax)
 	return ndctl_pfn_get_align(&dax->pfn);
 }
 
+NDCTL_EXPORT unsigned int ndctl_dax_get_num_alignments(struct ndctl_dax *dax)
+{
+	return ndctl_pfn_get_num_alignments(&dax->pfn);
+}
+
+NDCTL_EXPORT int ndctl_dax_get_supported_alignment(struct ndctl_dax *dax, int i)
+{
+	return ndctl_pfn_get_supported_alignment(&dax->pfn, i);
+}
+
 NDCTL_EXPORT int ndctl_dax_has_align(struct ndctl_dax *dax)
 {
 	return ndctl_pfn_has_align(&dax->pfn);
diff --git a/ndctl/lib/libndctl.sym b/ndctl/lib/libndctl.sym
index 6c4c8b4dfb8e..0103c1b71a1d 100644
--- a/ndctl/lib/libndctl.sym
+++ b/ndctl/lib/libndctl.sym
@@ -385,3 +385,10 @@ global:
 	ndctl_namespace_get_next_badblock;
 	ndctl_dimm_get_dirty_shutdown;
 } LIBNDCTL_17;
+
+LIBNDCTL_19 {
+	ndctl_pfn_get_supported_alignment;
+	ndctl_pfn_get_num_alignments;
+	ndctl_dax_get_supported_alignment;
+	ndctl_dax_get_num_alignments;
+} LIBNDCTL_18;
diff --git a/ndctl/libndctl.h b/ndctl/libndctl.h
index 62cef9e82da3..4ff25c0a4783 100644
--- a/ndctl/libndctl.h
+++ b/ndctl/libndctl.h
@@ -681,6 +681,12 @@ enum ND_FW_STATUS ndctl_cmd_fw_xlat_firmware_status(struct ndctl_cmd *cmd);
 struct ndctl_cmd *ndctl_dimm_cmd_new_ack_shutdown_count(struct ndctl_dimm *dimm);
 int ndctl_dimm_fw_update_supported(struct ndctl_dimm *dimm);
 
+unsigned int ndctl_pfn_get_num_alignments(struct ndctl_pfn *pfn);
+int ndctl_pfn_get_supported_alignment(struct ndctl_pfn *pfn, int i);
+
+unsigned int ndctl_dax_get_num_alignments(struct ndctl_dax *dax);
+int ndctl_dax_get_supported_alignment(struct ndctl_dax *dax, int i);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
-- 
2.17.2

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