[PATCH] fscrypt: Use lock guards for mutexes

[Eric Biggers <ebiggers@kernel.org>]

Replace all remaining calls to mutex_lock() and mutex_unlock() in
fs/crypto/ with lock guards.  No functional change.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---

This is intended to be taken through the fscrypt tree for 7.3

 fs/crypto/crypto.c   | 13 ++++---------
 fs/crypto/keyring.c  |  3 +--
 fs/crypto/keysetup.c | 23 +++++++++++------------
 3 files changed, 16 insertions(+), 23 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 570a2231c945..10097a3251f5 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -321,35 +321,30 @@ EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
  *
  * Return: 0 on success; -errno on failure
  */
 int fscrypt_initialize(struct super_block *sb)
 {
-	int err = 0;
 	mempool_t *pool;
 
 	/* pairs with smp_store_release() below */
 	if (likely(smp_load_acquire(&fscrypt_bounce_page_pool)))
 		return 0;
 
 	/* No need to allocate a bounce page pool if this FS won't use it. */
 	if (!sb->s_cop->needs_bounce_pages)
 		return 0;
 
-	mutex_lock(&fscrypt_init_mutex);
+	guard(mutex)(&fscrypt_init_mutex);
 	if (fscrypt_bounce_page_pool)
-		goto out_unlock;
+		return 0;
 
-	err = -ENOMEM;
 	pool = mempool_create_page_pool(num_prealloc_crypto_pages, 0);
 	if (!pool)
-		goto out_unlock;
+		return -ENOMEM;
 	/* pairs with smp_load_acquire() above */
 	smp_store_release(&fscrypt_bounce_page_pool, pool);
-	err = 0;
-out_unlock:
-	mutex_unlock(&fscrypt_init_mutex);
-	return err;
+	return 0;
 }
 
 void fscrypt_msg(const struct inode *inode, const char *level,
 		 const char *fmt, ...)
 {
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index 5fe0d985a58d..6ce6b436c34f 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -523,11 +523,11 @@ static int do_add_master_key(struct super_block *sb,
 {
 	static DEFINE_MUTEX(fscrypt_add_key_mutex);
 	struct fscrypt_master_key *mk;
 	int err;
 
-	mutex_lock(&fscrypt_add_key_mutex); /* serialize find + link */
+	guard(mutex)(&fscrypt_add_key_mutex); /* serialize find + link */
 
 	mk = fscrypt_find_master_key(sb, mk_spec);
 	if (!mk) {
 		/* Didn't find the key in ->s_master_keys.  Add it. */
 		err = allocate_filesystem_keyring(sb);
@@ -550,11 +550,10 @@ static int do_add_master_key(struct super_block *sb,
 			 */
 			err = add_new_master_key(sb, secret, mk_spec);
 		}
 		fscrypt_put_master_key(mk);
 	}
-	mutex_unlock(&fscrypt_add_key_mutex);
 	return err;
 }
 
 static int add_master_key(struct super_block *sb,
 			  struct fscrypt_master_key_secret *secret,
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index f905f9f94bdd..281b5a8b0bcd 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -347,22 +347,21 @@ static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_inode_info *ci,
 	if (err)
 		return err;
 
 	/* pairs with smp_store_release() below */
 	if (!smp_load_acquire(&mk->mk_ino_hash_key_initialized)) {
-
-		mutex_lock(&fscrypt_mode_key_setup_mutex);
-
-		if (mk->mk_ino_hash_key_initialized)
-			goto unlock;
-
-		fscrypt_derive_siphash_key(mk, HKDF_CONTEXT_INODE_HASH_KEY,
-					   NULL, 0, &mk->mk_ino_hash_key);
-		/* pairs with smp_load_acquire() above */
-		smp_store_release(&mk->mk_ino_hash_key_initialized, true);
-unlock:
-		mutex_unlock(&fscrypt_mode_key_setup_mutex);
+		guard(mutex)(&fscrypt_mode_key_setup_mutex);
+
+		if (!mk->mk_ino_hash_key_initialized) {
+			fscrypt_derive_siphash_key(mk,
+						   HKDF_CONTEXT_INODE_HASH_KEY,
+						   NULL, 0,
+						   &mk->mk_ino_hash_key);
+			/* pairs with smp_load_acquire() above */
+			smp_store_release(&mk->mk_ino_hash_key_initialized,
+					  true);
+		}
 	}
 
 	/*
 	 * New inodes may not have an inode number assigned yet.
 	 * Hashing their inode number is delayed until later.

base-commit: 83f1454877cc292b88baf13c829c16ce6937d120
prerequisite-patch-id: 319d2891e88c7df1ebb5ebf434d18b68f770399f
-- 
2.55.0.rc0.738.g0c8ab3ebcc-goog