DLPX-83701 Make function mnt_add_count() traceable (#17)

Don Brady · Delphix Engineering · commit 4fa55d7e4a7b · 2025-01-05T04:32:27.000Z
diff --git a/fs/namespace.c b/fs/namespace.c
@@ -163,7 +163,7 @@ 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);
@@ -1590,7 +1590,8 @@ 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
`@@ -163,7 +163,7 @@ void mnt_release_group_id(struct mount *mnt)`
`163`	`163`	`/*`
`164`	`164`	`* vfsmount lock must be held for read`
`165`	`165`	`*/`
`166`		`-static inline void mnt_add_count(struct mount *mnt, int n)`
	`166`	`+static noinline __noclone void mnt_add_count(struct mount *mnt, int n)`
`167`	`167`	`{`
`168`	`168`	`#ifdef CONFIG_SMP`
`169`	`169`	`this_cpu_add(mnt->mnt_pcp->mnt_count, n);`
`@@ -1590,7 +1590,8 @@ static int do_umount_root(struct super_block *sb)`
`1590`	`1590`	`return ret;`
`1591`	`1591`	`}`
`1592`	`1592`
`1593`		`-static int do_umount(struct mount *mnt, int flags)`
	`1593`	`+/* force a bpftrace dynamic function probe here */`
	`1594`	`+static noinline __noclone int do_umount(struct mount *mnt, int flags)`
`1594`	`1595`	`{`
`1595`	`1596`	`struct super_block *sb = mnt->mnt.mnt_sb;`
`1596`	`1597`	`int retval;`