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

Don Brady · Delphix Engineering · commit 9af04345a8fa · 2025-05-09T05:12:11.000Z
diff --git a/fs/namespace.c b/fs/namespace.c
@@ -169,7 +169,7 @@ 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);
@@ -1704,7 +1704,8 @@ 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
`@@ -169,7 +169,7 @@ void mnt_release_group_id(struct mount *mnt)`
`169`	`169`	`/*`
`170`	`170`	`* vfsmount lock must be held for read`
`171`	`171`	`*/`
`172`		`-static inline void mnt_add_count(struct mount *mnt, int n)`
	`172`	`+static noinline __noclone void mnt_add_count(struct mount *mnt, int n)`
`173`	`173`	`{`
`174`	`174`	`#ifdef CONFIG_SMP`
`175`	`175`	`this_cpu_add(mnt->mnt_pcp->mnt_count, n);`
`@@ -1704,7 +1704,8 @@ static int do_umount_root(struct super_block *sb)`
`1704`	`1704`	`return ret;`
`1705`	`1705`	`}`
`1706`	`1706`
`1707`		`-static int do_umount(struct mount *mnt, int flags)`
	`1707`	`+/* force a bpftrace dynamic function probe here */`
	`1708`	`+static noinline __noclone int do_umount(struct mount *mnt, int flags)`
`1708`	`1709`	`{`
`1709`	`1710`	`struct super_block *sb = mnt->mnt.mnt_sb;`
`1710`	`1711`	`int retval;`