DLPX-83701 Make function mnt_add_count() traceable (#24)

Don Brady · Delphix Engineering · commit 206f04f4448f · 2023-01-16T03:56:13.000Z
diff --git a/fs/namespace.c b/fs/namespace.c
@@ -142,7 +142,7 @@ 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);
@@ -1514,7 +1514,8 @@ 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
`@@ -142,7 +142,7 @@ void mnt_release_group_id(struct mount *mnt)`
`142`	`142`	`/*`
`143`	`143`	`* vfsmount lock must be held for read`
`144`	`144`	`*/`
`145`		`-static inline void mnt_add_count(struct mount *mnt, int n)`
	`145`	`+static noinline __noclone void mnt_add_count(struct mount *mnt, int n)`
`146`	`146`	`{`
`147`	`147`	`#ifdef CONFIG_SMP`
`148`	`148`	`this_cpu_add(mnt->mnt_pcp->mnt_count, n);`
`@@ -1514,7 +1514,8 @@ static int do_umount_root(struct super_block *sb)`
`1514`	`1514`	`return ret;`
`1515`	`1515`	`}`
`1516`	`1516`
`1517`		`-static int do_umount(struct mount *mnt, int flags)`
	`1517`	`+/* force a bpftrace dynamic function probe here */`
	`1518`	`+static noinline __noclone int do_umount(struct mount *mnt, int flags)`
`1518`	`1519`	`{`
`1519`	`1520`	`struct super_block *sb = mnt->mnt.mnt_sb;`
`1520`	`1521`	`int retval;`