nvme/029: reserve hugepages for lager allocations

The test is issuing larger IO workload. This depends on being able to
allocate larger chunks of linear memory. nvme-cli used to use libhugetlb
to automatically allocate the HugeTLB pool. Though nvme-cli dropped the
dependency on the library, thus the test should try to provision the
system accordingly.

Link: linux-nvme/nvme-cli#2218
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>

tests/nvme/029

@@ -54,6 +54,7 @@ test() {
 	_setup_nvmet
 
 	local nvmedev
+	local reset_nr_hugepages=false
 
 	_nvmet_target_setup
 
@@ -62,6 +63,15 @@ test() {
 	nvmedev=$(_find_nvme_dev "${def_subsysnqn}")
 	_check_uuid "${nvmedev}"
 
+	# nvme-cli may fail to allocate linear memory for rather large IO buffers.
+	# Increase nr_hugepages to allow nvme-cli to try the linear memory allocation
+	# from HugeTLB pool.
+	if [[  -r /proc/sys/vm/nr_hugepages &&
+		       "$(cat /proc/sys/vm/nr_hugepages)" -eq 0 ]]; then
+		echo 20 > /proc/sys/vm/nr_hugepages
+		reset_nr_hugepages=true
+	fi
+
 	local dev="/dev/${nvmedev}n1"
 	test_user_io "$dev" 1 512 > "$FULL" 2>&1 || echo FAIL
 	test_user_io "$dev" 1 511 > "$FULL" 2>&1 || echo FAIL
@@ -70,6 +80,10 @@ test() {
 	test_user_io "$dev" 511 1023 > "$FULL" 2>&1 || echo FAIL
 	test_user_io "$dev" 511 1025 > "$FULL" 2>&1 || echo FAIL
 
+	if [[ ${reset_nr_hugepages} = true ]]; then
+		echo 0 > /proc/sys/vm/nr_hugepages
+	fi
+
 	_nvme_disconnect_subsys "${def_subsysnqn}" >> "$FULL" 2>&1
 
 	_nvmet_target_cleanup