From 573f0d46cff15fff2804b3fb444d1e34f482e788 Mon Sep 17 00:00:00 2001

From: Vishal Verma <vishal.l.verma@intel.com>

Date: Tue, 30 Mar 2021 20:54:55 -0600

Subject: [PATCH 016/217] libndctl: check for active system-ram before

 disabling daxctl devices

Teach ndctl_namespace_disable_safe() to look at the state of a

daxctl_dev with respect to whether it is active in 'system-ram' mode

before disabling it. This is similar to checking whether a filesystem is

actively mounted on a namespace before disabling it.

Without this, libndctl would happily disable a devdax namespace while the

device was active in system-ram mode. If the namespace was subsequently

also destroyed, this would leave the memory without any sort of a

'handle' to perform any subsequent operation on it, and the system would

have to be rebooted to get out of this situation.

Reported-by: Chunye Xu <chunye.xu@intel.com>

Cc: Dan Williams <dan.j.williams@intel.com>

Cc: Dave Hansen <dave.hansen@linux.intel.com>

Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>

---

 ndctl/lib/libndctl.c   | 25 ++++++++++++++++++++++++-

 test/daxctl-devices.sh | 16 ++++++++++++++++

 2 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/ndctl/lib/libndctl.c b/ndctl/lib/libndctl.c

index 2f6d806..2eda56c 100644

--- a/ndctl/lib/libndctl.c

+++ b/ndctl/lib/libndctl.c

@@ -4593,21 +4593,40 @@ NDCTL_EXPORT int ndctl_namespace_disable_invalidate(struct ndctl_namespace *ndns

 	return ndctl_namespace_disable(ndns);

 }

+static int ndctl_dax_has_active_memory(struct ndctl_dax *dax)

+{

+	struct daxctl_region *dax_region;

+	struct daxctl_dev *dax_dev;

+

+	dax_region = ndctl_dax_get_daxctl_region(dax);

+	if (!dax_region)

+		return 0;

+

+	daxctl_dev_foreach(dax_region, dax_dev)

+		if (daxctl_dev_has_online_memory(dax_dev))

+			return 1;

+

+	return 0;

+}

+

 NDCTL_EXPORT int ndctl_namespace_disable_safe(struct ndctl_namespace *ndns)

 {

 	const char *devname = ndctl_namespace_get_devname(ndns);

 	struct ndctl_ctx *ctx = ndctl_namespace_get_ctx(ndns);

 	struct ndctl_pfn *pfn = ndctl_namespace_get_pfn(ndns);

 	struct ndctl_btt *btt = ndctl_namespace_get_btt(ndns);

+	struct ndctl_dax *dax = ndctl_namespace_get_dax(ndns);

 	const char *bdev = NULL;

+	int fd, active = 0;

 	char path[50];

-	int fd;

 	unsigned long long size = ndctl_namespace_get_size(ndns);

 	if (pfn && ndctl_pfn_is_enabled(pfn))

 		bdev = ndctl_pfn_get_block_device(pfn);

 	else if (btt && ndctl_btt_is_enabled(btt))

 		bdev = ndctl_btt_get_block_device(btt);

+	else if (dax && ndctl_dax_is_enabled(dax))

+		active = ndctl_dax_has_active_memory(dax);

 	else if (ndctl_namespace_is_enabled(ndns))

 		bdev = ndctl_namespace_get_block_device(ndns);

@@ -4632,6 +4651,10 @@ NDCTL_EXPORT int ndctl_namespace_disable_safe(struct ndctl_namespace *ndns)

 					devname, bdev, strerror(errno));

 			return -errno;

 		}

+	} else if (active) {

+		dbg(ctx, "%s: active as system-ram, refusing to disable\n",

+				devname);

+		return -EBUSY;

 	} else {

 		if (size == 0)

 			/* No disable necessary due to no capacity allocated */

diff --git a/test/daxctl-devices.sh b/test/daxctl-devices.sh

index eed5906..56c9691 100755

--- a/test/daxctl-devices.sh

+++ b/test/daxctl-devices.sh

@@ -105,6 +105,22 @@ daxctl_test()

 	"$DAXCTL" reconfigure-device -f -m devdax "$daxdev"

 	[[ $(daxctl_get_mode "$daxdev") == "devdax" ]]

+	# fail 'ndctl-disable-namespace' while the devdax namespace is active

+	# as system-ram. If this test fails, a reboot will be required to

+	# recover from the resulting state.

+	test -n "$testdev"

+	"$DAXCTL" reconfigure-device -m system-ram "$daxdev"

+	[[ $(daxctl_get_mode "$daxdev") == "system-ram" ]]

+	if ! "$NDCTL" disable-namespace "$testdev"; then

+		echo "disable-namespace failed as expected"

+	else

+		echo "disable-namespace succeded, expected failure"

+		echo "reboot required to recover from this state"

+		return 1

+	fi

+	"$DAXCTL" reconfigure-device -f -m devdax "$daxdev"

+	[[ $(daxctl_get_mode "$daxdev") == "devdax" ]]

+

 	# this tests for reconfiguration failure if an online-policy is set

 	set_online_policy

 	: "This command is expected to fail:"

-- 

2.27.0