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From: Vishal Verma <vishal.l.verma@intel.com>
To: <linux-nvdimm@lists.01.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Subject: [ndctl PATCH v2 2/2] ndctl/namespace: introduce ndctl_namespace_is_configuration_idle()
Date: Mon,  4 Nov 2019 13:08:22 -0700
Message-ID: <20191104200822.28959-2-vishal.l.verma@intel.com> (raw)
In-Reply-To: <20191104200822.28959-1-vishal.l.verma@intel.com>

The motivation for this change is that we want to refrain from
(re)configuring what appear to be partially configured namespaces.
Namespaces may end up in a state that looks partially configured when
the kernel isn't able to enable a namespace due to mismatched
PAGE_SIZE expectations. In such cases, ndctl should not treat those
as unconfigured 'seed' namespaces, and reuse them.

Add a new ndctl_namespace_is_configuration_idle API, whish tests whether a
namespace is active, and whether it is partially configured. If neither
are true, then it can be used for (re)configuration. Additionally, deal
with the corner case of ND_DEVICE_NAMESPACE_IO (legacy PMEM) namespaces
which always appear as configured, since their size cannot be changed,
but they are also always re-configurable.

Use this API in namespace_reconfig() and namespace_create() to enable
this partial configuration detection.

Cc: Dan Williams <dan.j.williams@intel.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
---

Changes in v2:
- Remove sysfs_attr_writable, and just check for the nstype of
  ND_DEVICE_NAMESPACE_IO (Dan)
- Rename ndctl_namespace_is_configurable to
  ndctl_namespace_is_configuration_idle (Dan)

 ndctl/lib/libndctl.c   | 36 ++++++++++++++++++++++++++++++++++++
 ndctl/lib/libndctl.sym |  4 ++++
 ndctl/libndctl.h       |  1 +
 ndctl/namespace.c      |  6 +++---
 util/sysfs.c           |  1 +
 util/sysfs.h           |  1 +
 6 files changed, 46 insertions(+), 3 deletions(-)

diff --git a/ndctl/lib/libndctl.c b/ndctl/lib/libndctl.c
index 6596f94..663d09a 100644
--- a/ndctl/lib/libndctl.c
+++ b/ndctl/lib/libndctl.c
@@ -3985,6 +3985,21 @@ static void region_refresh_children(struct ndctl_region *region)
 	daxs_init(region);
 }
 
+static bool namespace_size_is_writeable(struct ndctl_namespace *ndns)
+{
+	struct ndctl_ctx *ctx = ndctl_namespace_get_ctx(ndns);
+	char *path = ndns->ndns_buf;
+	int len = ndns->buf_len;
+
+	if (snprintf(path, len, "%s/size", ndns->ndns_path) >= len) {
+		err(ctx, "%s: buffer too small!\n",
+				ndctl_namespace_get_devname(ndns));
+		return false;
+	}
+
+	return sysfs_attr_writable(ctx, path);
+}
+
 NDCTL_EXPORT bool ndctl_namespace_is_active(struct ndctl_namespace *ndns)
 {
 	struct ndctl_btt *btt = ndctl_namespace_get_btt(ndns);
@@ -4182,6 +4197,27 @@ NDCTL_EXPORT int ndctl_namespace_is_configured(struct ndctl_namespace *ndns)
 	}
 }
 
+/*
+ * Check if a given 'seed' namespace is ok to configure.
+ * If a size or uuid is present, it is considered not configuration-idle,
+ * except in the case of legacy (ND_DEVICE_NAMESPACE_IO) namespaces. In
+ * that case, the size is never zero, but the namespace can still be
+ * reconfigured.
+ */
+NDCTL_EXPORT int ndctl_namespace_is_configuration_idle(
+		struct ndctl_namespace *ndns)
+{
+	if (ndctl_namespace_is_active(ndns))
+		return 0;
+	if (ndctl_namespace_is_configured(ndns)) {
+		if (ndctl_namespace_get_type(ndns) == ND_DEVICE_NAMESPACE_IO)
+			return 1;
+		return 0;
+	}
+	/* !active and !configured is configuration-idle */
+	return 1;
+}
+
 NDCTL_EXPORT void ndctl_namespace_get_uuid(struct ndctl_namespace *ndns, uuid_t uu)
 {
 	memcpy(uu, ndns->uuid, sizeof(uuid_t));
diff --git a/ndctl/lib/libndctl.sym b/ndctl/lib/libndctl.sym
index c93c1ee..4e76778 100644
--- a/ndctl/lib/libndctl.sym
+++ b/ndctl/lib/libndctl.sym
@@ -423,3 +423,7 @@ LIBNDCTL_21 {
 LIBNDCTL_22 {
 	ndctl_dimm_security_is_frozen;
 } LIBNDCTL_21;
+
+LIBNDCTL_23 {
+	ndctl_namespace_is_configuration_idle;
+} LIBNDCTL_22;
diff --git a/ndctl/libndctl.h b/ndctl/libndctl.h
index db398b3..9a53049 100644
--- a/ndctl/libndctl.h
+++ b/ndctl/libndctl.h
@@ -491,6 +491,7 @@ int ndctl_namespace_disable_safe(struct ndctl_namespace *ndns);
 bool ndctl_namespace_is_active(struct ndctl_namespace *ndns);
 int ndctl_namespace_is_valid(struct ndctl_namespace *ndns);
 int ndctl_namespace_is_configured(struct ndctl_namespace *ndns);
+int ndctl_namespace_is_configuration_idle(struct ndctl_namespace *ndns);
 int ndctl_namespace_delete(struct ndctl_namespace *ndns);
 int ndctl_namespace_set_uuid(struct ndctl_namespace *ndns, uuid_t uu);
 void ndctl_namespace_get_uuid(struct ndctl_namespace *ndns, uuid_t uu);
diff --git a/ndctl/namespace.c b/ndctl/namespace.c
index ccd46d0..a07d7e2 100644
--- a/ndctl/namespace.c
+++ b/ndctl/namespace.c
@@ -779,7 +779,7 @@ static struct ndctl_namespace *region_get_namespace(struct ndctl_region *region)
 	/* prefer the 0th namespace if it is idle */
 	ndctl_namespace_foreach(region, ndns)
 		if (ndctl_namespace_get_id(ndns) == 0
-				&& !ndctl_namespace_is_active(ndns))
+				&& ndctl_namespace_is_configuration_idle(ndns))
 			return ndns;
 	return ndctl_region_get_namespace_seed(region);
 }
@@ -819,7 +819,7 @@ static int namespace_create(struct ndctl_region *region)
 		p.size = available;
 
 	ndns = region_get_namespace(region);
-	if (!ndns || ndctl_namespace_is_active(ndns)) {
+	if (!ndns || !ndctl_namespace_is_configuration_idle(ndns)) {
 		debug("%s: no %s namespace seed\n", devname,
 				ndns ? "idle" : "available");
 		return -EAGAIN;
@@ -1066,7 +1066,7 @@ static int namespace_reconfig(struct ndctl_region *region,
 	}
 
 	ndns = region_get_namespace(region);
-	if (!ndns || !ndctl_namespace_is_active(ndns)) {
+	if (!ndns || !ndctl_namespace_is_configuration_idle(ndns)) {
 		debug("%s: no %s namespace seed\n",
 				ndctl_region_get_devname(region),
 				ndns ? "idle" : "available");
diff --git a/util/sysfs.c b/util/sysfs.c
index 9f7bc1f..81cd055 100644
--- a/util/sysfs.c
+++ b/util/sysfs.c
@@ -20,6 +20,7 @@
 #include <ctype.h>
 #include <fcntl.h>
 #include <dirent.h>
+#include <stdbool.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/ioctl.h>
diff --git a/util/sysfs.h b/util/sysfs.h
index fb169c6..b2d28f1 100644
--- a/util/sysfs.h
+++ b/util/sysfs.h
@@ -14,6 +14,7 @@
 #define __UTIL_SYSFS_H__
 
 #include <string.h>
+#include <stdbool.h>
 
 typedef void *(*add_dev_fn)(void *parent, int id, const char *dev_path);
 
-- 
2.20.1
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Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-04 20:08 [ndctl PATCH v2 1/2] ndctl/namespace: remove open coded is_namespace_active() Vishal Verma
2019-11-04 20:08 ` Vishal Verma [this message]
2019-11-04 20:09   ` [ndctl PATCH v2 2/2] ndctl/namespace: introduce ndctl_namespace_is_configuration_idle() Verma, Vishal L

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