DLPX-83701 Make function mnt_add_count() traceable (#16)

Don Brady · Delphix Engineering · commit 2faf02ac751a · 2026-02-27T05:44:27.000Z
diff --git a/fs/namespace.c b/fs/namespace.c
@@ -326,7 +326,7 @@ void mnt_release_group_id(struct mount *mnt)
 /*
  * vfsmount lock must be held for read
  */
-static inline void mnt_add_count(struct mount *mnt, int n)
+static noinline __noclone void mnt_add_count(struct mount *mnt, int n)
 {
 #ifdef CONFIG_SMP
 	this_cpu_add(mnt->mnt_pcp->mnt_count, n);
@@ -1920,7 +1920,8 @@ static int do_umount_root(struct super_block *sb)
 	return ret;
 }
 
-static int do_umount(struct mount *mnt, int flags)
+/* force a bpftrace dynamic function probe here */
+static noinline __noclone int do_umount(struct mount *mnt, int flags)
 {
 	struct super_block *sb = mnt->mnt.mnt_sb;
 	int retval;

Original file line number	Diff line number	Diff line change
`@@ -326,7 +326,7 @@ void mnt_release_group_id(struct mount *mnt)`
`326`	`326`	`/*`
`327`	`327`	`* vfsmount lock must be held for read`
`328`	`328`	`*/`
`329`		`-static inline void mnt_add_count(struct mount *mnt, int n)`
	`329`	`+static noinline __noclone void mnt_add_count(struct mount *mnt, int n)`
`330`	`330`	`{`
`331`	`331`	`#ifdef CONFIG_SMP`
`332`	`332`	`this_cpu_add(mnt->mnt_pcp->mnt_count, n);`
`@@ -1920,7 +1920,8 @@ static int do_umount_root(struct super_block *sb)`
`1920`	`1920`	`return ret;`
`1921`	`1921`	`}`
`1922`	`1922`
`1923`		`-static int do_umount(struct mount *mnt, int flags)`
	`1923`	`+/* force a bpftrace dynamic function probe here */`
	`1924`	`+static noinline __noclone int do_umount(struct mount *mnt, int flags)`
`1924`	`1925`	`{`
`1925`	`1926`	`struct super_block *sb = mnt->mnt.mnt_sb;`
`1926`	`1927`	`int retval;`