[PATCH v7 12/14] fs/resctrl: Call architecture hooks for every mount/unmount

[Tony Luck]

The intel_pmt module should only be pinned while the resctrl file system
is mounted.

Add hooks for every mount/unmount of the resctrl file system so that
architecture code can increment the intel_pmt module reference count on
mount and decrement on unmount.

Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
 include/linux/resctrl.h | 7 +++++--
 fs/resctrl/rdtgroup.c   | 9 +++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 9534d42e0c57..e8a87c3664db 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -552,12 +552,15 @@ void resctrl_online_cpu(unsigned int cpu);
 void resctrl_offline_cpu(unsigned int cpu);
 
 /*
- * Architecture hook called at beginning of first file system mount attempt.
+ * Architecture hook called before attempting to mount the file system.
  * No locks are held.
  */
 void resctrl_arch_pre_mount(void);
 
-/* Called to report unmount. */
+/*
+ * Architecture hook called when mount fails, or on unmount.
+ * No locks are held.
+ */
 void resctrl_arch_unmount(void);
 
 /**
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 6d647b71c5db..195ebb15c5f0 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -18,7 +18,6 @@
 #include <linux/fs_parser.h>
 #include <linux/sysfs.h>
 #include <linux/kernfs.h>
-#include <linux/once.h>
 #include <linux/resctrl.h>
 #include <linux/seq_buf.h>
 #include <linux/seq_file.h>
@@ -2998,6 +2997,8 @@ static void resctrl_unmount(void)
 	resctrl_mounted = false;
 	mutex_unlock(&rdtgroup_mutex);
 	cpus_read_unlock();
+
+	resctrl_arch_unmount();
 }
 
 static int rdt_get_tree(struct fs_context *fc)
@@ -3009,7 +3010,7 @@ static int rdt_get_tree(struct fs_context *fc)
 	struct rdt_resource *r;
 	int ret;
 
-	DO_ONCE_SLEEPABLE(resctrl_arch_pre_mount);
+	resctrl_arch_pre_mount();
 
 	cpus_read_lock();
 	mutex_lock(&rdtgroup_mutex);
@@ -3147,6 +3148,10 @@ static int rdt_get_tree(struct fs_context *fc)
 out:
 	mutex_unlock(&rdtgroup_mutex);
 	cpus_read_unlock();
+
+	if (ret)
+		resctrl_arch_unmount();
+
 	return ret;
 }
 
-- 
2.54.0