Merge tag 'kernel-6.14-rc1.cred' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull cred refcount updates from Christian Brauner:
 "For the v6.13 cycle we switched overlayfs to a variant of
  override_creds() that doesn't take an extra reference. To this end the
  {override,revert}_creds_light() helpers were introduced.

  This generalizes the idea behind {override,revert}_creds_light() to
  the {override,revert}_creds() helpers. Afterwards overriding and
  reverting credentials is reference count free unless the caller
  explicitly takes a reference.

  All callers have been appropriately ported"

* tag 'kernel-6.14-rc1.cred' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (30 commits)
  cred: fold get_new_cred_many() into get_cred_many()
  cred: remove unused get_new_cred()
  nfsd: avoid pointless cred reference count bump
  cachefiles: avoid pointless cred reference count bump
  dns_resolver: avoid pointless cred reference count bump
  trace: avoid pointless cred reference count bump
  cgroup: avoid pointless cred reference count bump
  acct: avoid pointless reference count bump
  io_uring: avoid pointless cred reference count bump
  smb: avoid pointless cred reference count bump
  cifs: avoid pointless cred reference count bump
  cifs: avoid pointless cred reference count bump
  ovl: avoid pointless cred reference count bump
  open: avoid pointless cred reference count bump
  nfsfh: avoid pointless cred reference count bump
  nfs/nfs4recover: avoid pointless cred reference count bump
  nfs/nfs4idmap: avoid pointless reference count bump
  nfs/localio: avoid pointless cred reference count bumps
  coredump: avoid pointless cred reference count bump
  binfmt_misc: avoid pointless cred reference count bump
  ...

1 files changed, 7 insertions, 36 deletions

diff --git a/include/linux/cred.h b/include/linux/cred.h
index e4a3155fe409..0c3c4b16b469 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -155,8 +155,6 @@ extern struct cred *prepare_creds(void);
 extern struct cred *prepare_exec_creds(void);
 extern int commit_creds(struct cred *);
 extern void abort_creds(struct cred *);
-extern const struct cred *override_creds(const struct cred *);
-extern void revert_creds(const struct cred *);
 extern struct cred *prepare_kernel_cred(struct task_struct *);
 extern int set_security_override(struct cred *, u32);
 extern int set_security_override_from_ctx(struct cred *, const char *);
@@ -172,12 +170,7 @@ static inline bool cap_ambient_invariant_ok(const struct cred *cred)
 					  cred->cap_inheritable));
 }
 
-/*
- * Override creds without bumping reference count. Caller must ensure
- * reference remains valid or has taken reference. Almost always not the
- * interface you want. Use override_creds()/revert_creds() instead.
- */
-static inline const struct cred *override_creds_light(const struct cred *override_cred)
+static inline const struct cred *override_creds(const struct cred *override_cred)
 {
 	const struct cred *old = current->cred;
 
@@ -185,35 +178,12 @@ static inline const struct cred *override_creds_light(const struct cred *overrid
 	return old;
 }
 
-static inline void revert_creds_light(const struct cred *revert_cred)
-{
-	rcu_assign_pointer(current->cred, revert_cred);
-}
-
-/**
- * get_new_cred_many - Get references on a new set of credentials
- * @cred: The new credentials to reference
- * @nr: Number of references to acquire
- *
- * Get references on the specified set of new credentials.  The caller must
- * release all acquired references.
- */
-static inline struct cred *get_new_cred_many(struct cred *cred, int nr)
+static inline const struct cred *revert_creds(const struct cred *revert_cred)
 {
-	atomic_long_add(nr, &cred->usage);
-	return cred;
-}
+	const struct cred *override_cred = current->cred;
 
-/**
- * get_new_cred - Get a reference on a new set of credentials
- * @cred: The new credentials to reference
- *
- * Get a reference on the specified set of new credentials.  The caller must
- * release the reference.
- */
-static inline struct cred *get_new_cred(struct cred *cred)
-{
-	return get_new_cred_many(cred, 1);
+	rcu_assign_pointer(current->cred, revert_cred);
+	return override_cred;
 }
 
 /**
@@ -236,7 +206,8 @@ static inline const struct cred *get_cred_many(const struct cred *cred, int nr)
 	if (!cred)
 		return cred;
 	nonconst_cred->non_rcu = 0;
-	return get_new_cred_many(nonconst_cred, nr);
+	atomic_long_add(nr, &nonconst_cred->usage);
+	return cred;
 }
 
 /*