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

Don Brady · Delphix Engineering · commit d3dec751d4ec · 2025-09-26T05:34:19.000Z
diff --git a/fs/namespace.c b/fs/namespace.c
@@ -306,7 +306,7 @@ 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);
@@ -1870,7 +1870,8 @@ 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
`@@ -306,7 +306,7 @@ void mnt_release_group_id(struct mount *mnt)`
`306`	`306`	`/*`
`307`	`307`	`* vfsmount lock must be held for read`
`308`	`308`	`*/`
`309`		`-static inline void mnt_add_count(struct mount *mnt, int n)`
	`309`	`+static noinline __noclone void mnt_add_count(struct mount *mnt, int n)`
`310`	`310`	`{`
`311`	`311`	`#ifdef CONFIG_SMP`
`312`	`312`	`this_cpu_add(mnt->mnt_pcp->mnt_count, n);`
`@@ -1870,7 +1870,8 @@ static int do_umount_root(struct super_block *sb)`
`1870`	`1870`	`return ret;`
`1871`	`1871`	`}`
`1872`	`1872`
`1873`		`-static int do_umount(struct mount *mnt, int flags)`
	`1873`	`+/* force a bpftrace dynamic function probe here */`
	`1874`	`+static noinline __noclone int do_umount(struct mount *mnt, int flags)`
`1874`	`1875`	`{`
`1875`	`1876`	`struct super_block *sb = mnt->mnt.mnt_sb;`
`1876`	`1877`	`int retval;`