diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h
index 052ad40..b746d7d 100644
--- a/fs/crypto/fscrypt_private.h
+++ b/fs/crypto/fscrypt_private.h
@@ -220,7 +220,7 @@
 	 * will be NULL if the master key was found in a process-subscribed
 	 * keyring rather than in the filesystem-level keyring.
 	 */
-	struct key *ci_master_key;
+	struct fscrypt_master_key *ci_master_key;
 
 	/*
 	 * Link in list of inodes that were unlocked with the master key.
@@ -432,6 +432,40 @@
 struct fscrypt_master_key {
 
 	/*
+	 * Back-pointer to the super_block of the filesystem to which this
+	 * master key has been added.  Only valid if ->mk_active_refs > 0.
+	 */
+	struct super_block			*mk_sb;
+
+	/*
+	 * Link in ->mk_sb->s_master_keys->key_hashtable.
+	 * Only valid if ->mk_active_refs > 0.
+	 */
+	struct hlist_node			mk_node;
+
+	/* Semaphore that protects ->mk_secret and ->mk_users */
+	struct rw_semaphore			mk_sem;
+
+	/*
+	 * Active and structural reference counts.  An active ref guarantees
+	 * that the struct continues to exist, continues to be in the keyring
+	 * ->mk_sb->s_master_keys, and that any embedded subkeys (e.g.
+	 * ->mk_direct_keys) that have been prepared continue to exist.
+	 * A structural ref only guarantees that the struct continues to exist.
+	 *
+	 * There is one active ref associated with ->mk_secret being present,
+	 * and one active ref for each inode in ->mk_decrypted_inodes.
+	 *
+	 * There is one structural ref associated with the active refcount being
+	 * nonzero.  Finding a key in the keyring also takes a structural ref,
+	 * which is then held temporarily while the key is operated on.
+	 */
+	refcount_t				mk_active_refs;
+	refcount_t				mk_struct_refs;
+
+	struct rcu_head				mk_rcu_head;
+
+	/*
 	 * The secret key material.  After FS_IOC_REMOVE_ENCRYPTION_KEY is
 	 * executed, this is wiped and no new inodes can be unlocked with this
 	 * key; however, there may still be inodes in ->mk_decrypted_inodes
@@ -439,16 +473,12 @@
 	 * FS_IOC_REMOVE_ENCRYPTION_KEY can be retried, or
 	 * FS_IOC_ADD_ENCRYPTION_KEY can add the secret again.
 	 *
-	 * Locking: protected by key->sem (outer) and mk_secret_sem (inner).
-	 * The reason for two locks is that key->sem also protects modifying
-	 * mk_users, which ranks it above the semaphore for the keyring key
-	 * type, which is in turn above page faults (via keyring_read).  But
-	 * sometimes filesystems call fscrypt_get_encryption_info() from within
-	 * a transaction, which ranks it below page faults.  So we need a
-	 * separate lock which protects mk_secret but not also mk_users.
+	 * While ->mk_secret is present, one ref in ->mk_active_refs is held.
+	 *
+	 * Locking: protected by ->mk_sem.  The manipulation of ->mk_active_refs
+	 *	    associated with this field is protected by ->mk_sem as well.
 	 */
 	struct fscrypt_master_key_secret	mk_secret;
-	struct rw_semaphore			mk_secret_sem;
 
 	/*
 	 * For v1 policy keys: an arbitrary key descriptor which was assigned by
@@ -467,23 +497,13 @@
 	 *
 	 * This is NULL for v1 policy keys; those can only be added by root.
 	 *
-	 * Locking: in addition to this keyrings own semaphore, this is
-	 * protected by the master key's key->sem, so we can do atomic
-	 * search+insert.  It can also be searched without taking any locks, but
-	 * in that case the returned key may have already been removed.
+	 * Locking: protected by ->mk_sem.  (We don't just rely on the keyrings
+	 * subsystem semaphore ->mk_users->sem, as we need support for atomic
+	 * search+insert along with proper synchronization with ->mk_secret.)
 	 */
 	struct key		*mk_users;
 
 	/*
-	 * Length of ->mk_decrypted_inodes, plus one if mk_secret is present.
-	 * Once this goes to 0, the master key is removed from ->s_master_keys.
-	 * The 'struct fscrypt_master_key' will continue to live as long as the
-	 * 'struct key' whose payload it is, but we won't let this reference
-	 * count rise again.
-	 */
-	refcount_t		mk_refcount;
-
-	/*
 	 * List of inodes that were unlocked using this key.  This allows the
 	 * inodes to be evicted efficiently if the key is removed.
 	 */
@@ -508,11 +528,11 @@
 is_master_key_secret_present(const struct fscrypt_master_key_secret *secret)
 {
 	/*
-	 * The READ_ONCE() is only necessary for fscrypt_drop_inode() and
-	 * fscrypt_key_describe().  These run in atomic context, so they can't
-	 * take ->mk_secret_sem and thus 'secret' can change concurrently which
-	 * would be a data race.  But they only need to know whether the secret
-	 * *was* present at the time of check, so READ_ONCE() suffices.
+	 * The READ_ONCE() is only necessary for fscrypt_drop_inode().
+	 * fscrypt_drop_inode() runs in atomic context, so it can't take the key
+	 * semaphore and thus 'secret' can change concurrently which would be a
+	 * data race.  But fscrypt_drop_inode() only need to know whether the
+	 * secret *was* present at the time of check, so READ_ONCE() suffices.
 	 */
 	return READ_ONCE(secret->size) != 0;
 }
@@ -540,7 +560,11 @@
 	return 0;
 }
 
-struct key *
+void fscrypt_put_master_key(struct fscrypt_master_key *mk);
+
+void fscrypt_put_master_key_activeref(struct fscrypt_master_key *mk);
+
+struct fscrypt_master_key *
 fscrypt_find_master_key(struct super_block *sb,
 			const struct fscrypt_key_specifier *mk_spec);
 
diff --git a/fs/crypto/hooks.c b/fs/crypto/hooks.c
index 4180371..8268206 100644
--- a/fs/crypto/hooks.c
+++ b/fs/crypto/hooks.c
@@ -5,8 +5,6 @@
  * Encryption hooks for higher-level filesystem operations.
  */
 
-#include <linux/key.h>
-
 #include "fscrypt_private.h"
 
 /**
@@ -154,13 +152,13 @@
 		ci = inode->i_crypt_info;
 		if (ci->ci_policy.version != FSCRYPT_POLICY_V2)
 			return -EINVAL;
-		mk = ci->ci_master_key->payload.data[0];
-		down_read(&mk->mk_secret_sem);
+		mk = ci->ci_master_key;
+		down_read(&mk->mk_sem);
 		if (is_master_key_secret_present(&mk->mk_secret))
 			err = fscrypt_derive_dirhash_key(ci, mk);
 		else
 			err = -ENOKEY;
-		up_read(&mk->mk_secret_sem);
+		up_read(&mk->mk_sem);
 		return err;
 	}
 	return 0;
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c
index d7ec52c..02f8bf8 100644
--- a/fs/crypto/keyring.c
+++ b/fs/crypto/keyring.c
@@ -18,6 +18,7 @@
  * information about these ioctls.
  */
 
+#include <asm/unaligned.h>
 #include <crypto/skcipher.h>
 #include <linux/key-type.h>
 #include <linux/random.h>
@@ -25,6 +26,18 @@
 
 #include "fscrypt_private.h"
 
+/* The master encryption keys for a filesystem (->s_master_keys) */
+struct fscrypt_keyring {
+	/*
+	 * Lock that protects ->key_hashtable.  It does *not* protect the
+	 * fscrypt_master_key structs themselves.
+	 */
+	spinlock_t lock;
+
+	/* Hash table that maps fscrypt_key_specifier to fscrypt_master_key */
+	struct hlist_head key_hashtable[128];
+};
+
 static void wipe_master_key_secret(struct fscrypt_master_key_secret *secret)
 {
 	fscrypt_destroy_hkdf(&secret->hkdf);
@@ -38,20 +51,70 @@
 	memzero_explicit(src, sizeof(*src));
 }
 
-static void free_master_key(struct fscrypt_master_key *mk)
+static void fscrypt_free_master_key(struct rcu_head *head)
 {
+	struct fscrypt_master_key *mk =
+		container_of(head, struct fscrypt_master_key, mk_rcu_head);
+	/*
+	 * The master key secret and any embedded subkeys should have already
+	 * been wiped when the last active reference to the fscrypt_master_key
+	 * struct was dropped; doing it here would be unnecessarily late.
+	 * Nevertheless, use kfree_sensitive() in case anything was missed.
+	 */
+	kfree_sensitive(mk);
+}
+
+void fscrypt_put_master_key(struct fscrypt_master_key *mk)
+{
+	if (!refcount_dec_and_test(&mk->mk_struct_refs))
+		return;
+	/*
+	 * No structural references left, so free ->mk_users, and also free the
+	 * fscrypt_master_key struct itself after an RCU grace period ensures
+	 * that concurrent keyring lookups can no longer find it.
+	 */
+	WARN_ON(refcount_read(&mk->mk_active_refs) != 0);
+	key_put(mk->mk_users);
+	mk->mk_users = NULL;
+	call_rcu(&mk->mk_rcu_head, fscrypt_free_master_key);
+}
+
+void fscrypt_put_master_key_activeref(struct fscrypt_master_key *mk)
+{
+	struct super_block *sb = mk->mk_sb;
+	struct fscrypt_keyring *keyring = sb->s_master_keys;
 	size_t i;
 
-	wipe_master_key_secret(&mk->mk_secret);
+	if (!refcount_dec_and_test(&mk->mk_active_refs))
+		return;
+	/*
+	 * No active references left, so complete the full removal of this
+	 * fscrypt_master_key struct by removing it from the keyring and
+	 * destroying any subkeys embedded in it.
+	 */
+
+	spin_lock(&keyring->lock);
+	hlist_del_rcu(&mk->mk_node);
+	spin_unlock(&keyring->lock);
+
+	/*
+	 * ->mk_active_refs == 0 implies that ->mk_secret is not present and
+	 * that ->mk_decrypted_inodes is empty.
+	 */
+	WARN_ON(is_master_key_secret_present(&mk->mk_secret));
+	WARN_ON(!list_empty(&mk->mk_decrypted_inodes));
 
 	for (i = 0; i <= FSCRYPT_MODE_MAX; i++) {
 		fscrypt_destroy_prepared_key(&mk->mk_direct_keys[i]);
 		fscrypt_destroy_prepared_key(&mk->mk_iv_ino_lblk_64_keys[i]);
 		fscrypt_destroy_prepared_key(&mk->mk_iv_ino_lblk_32_keys[i]);
 	}
+	memzero_explicit(&mk->mk_ino_hash_key,
+			 sizeof(mk->mk_ino_hash_key));
+	mk->mk_ino_hash_key_initialized = false;
 
-	key_put(mk->mk_users);
-	kfree_sensitive(mk);
+	/* Drop the structural ref associated with the active refs. */
+	fscrypt_put_master_key(mk);
 }
 
 static inline bool valid_key_spec(const struct fscrypt_key_specifier *spec)
@@ -61,44 +124,6 @@
 	return master_key_spec_len(spec) != 0;
 }
 
-static int fscrypt_key_instantiate(struct key *key,
-				   struct key_preparsed_payload *prep)
-{
-	key->payload.data[0] = (struct fscrypt_master_key *)prep->data;
-	return 0;
-}
-
-static void fscrypt_key_destroy(struct key *key)
-{
-	free_master_key(key->payload.data[0]);
-}
-
-static void fscrypt_key_describe(const struct key *key, struct seq_file *m)
-{
-	seq_puts(m, key->description);
-
-	if (key_is_positive(key)) {
-		const struct fscrypt_master_key *mk = key->payload.data[0];
-
-		if (!is_master_key_secret_present(&mk->mk_secret))
-			seq_puts(m, ": secret removed");
-	}
-}
-
-/*
- * Type of key in ->s_master_keys.  Each key of this type represents a master
- * key which has been added to the filesystem.  Its payload is a
- * 'struct fscrypt_master_key'.  The "." prefix in the key type name prevents
- * users from adding keys of this type via the keyrings syscalls rather than via
- * the intended method of FS_IOC_ADD_ENCRYPTION_KEY.
- */
-static struct key_type key_type_fscrypt = {
-	.name			= "._fscrypt",
-	.instantiate		= fscrypt_key_instantiate,
-	.destroy		= fscrypt_key_destroy,
-	.describe		= fscrypt_key_describe,
-};
-
 static int fscrypt_user_key_instantiate(struct key *key,
 					struct key_preparsed_payload *prep)
 {
@@ -131,32 +156,6 @@
 	.describe		= fscrypt_user_key_describe,
 };
 
-/* Search ->s_master_keys or ->mk_users */
-static struct key *search_fscrypt_keyring(struct key *keyring,
-					  struct key_type *type,
-					  const char *description)
-{
-	/*
-	 * We need to mark the keyring reference as "possessed" so that we
-	 * acquire permission to search it, via the KEY_POS_SEARCH permission.
-	 */
-	key_ref_t keyref = make_key_ref(keyring, true /* possessed */);
-
-	keyref = keyring_search(keyref, type, description, false);
-	if (IS_ERR(keyref)) {
-		if (PTR_ERR(keyref) == -EAGAIN || /* not found */
-		    PTR_ERR(keyref) == -EKEYREVOKED) /* recently invalidated */
-			keyref = ERR_PTR(-ENOKEY);
-		return ERR_CAST(keyref);
-	}
-	return key_ref_to_ptr(keyref);
-}
-
-#define FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE	\
-	(CONST_STRLEN("fscrypt-") + sizeof_field(struct super_block, s_id))
-
-#define FSCRYPT_MK_DESCRIPTION_SIZE	(2 * FSCRYPT_KEY_IDENTIFIER_SIZE + 1)
-
 #define FSCRYPT_MK_USERS_DESCRIPTION_SIZE	\
 	(CONST_STRLEN("fscrypt-") + 2 * FSCRYPT_KEY_IDENTIFIER_SIZE + \
 	 CONST_STRLEN("-users") + 1)
@@ -164,21 +163,6 @@
 #define FSCRYPT_MK_USER_DESCRIPTION_SIZE	\
 	(2 * FSCRYPT_KEY_IDENTIFIER_SIZE + CONST_STRLEN(".uid.") + 10 + 1)
 
-static void format_fs_keyring_description(
-			char description[FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE],
-			const struct super_block *sb)
-{
-	sprintf(description, "fscrypt-%s", sb->s_id);
-}
-
-static void format_mk_description(
-			char description[FSCRYPT_MK_DESCRIPTION_SIZE],
-			const struct fscrypt_key_specifier *mk_spec)
-{
-	sprintf(description, "%*phN",
-		master_key_spec_len(mk_spec), (u8 *)&mk_spec->u);
-}
-
 static void format_mk_users_keyring_description(
 			char description[FSCRYPT_MK_USERS_DESCRIPTION_SIZE],
 			const u8 mk_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE])
@@ -199,20 +183,15 @@
 /* Create ->s_master_keys if needed.  Synchronized by fscrypt_add_key_mutex. */
 static int allocate_filesystem_keyring(struct super_block *sb)
 {
-	char description[FSCRYPT_FS_KEYRING_DESCRIPTION_SIZE];
-	struct key *keyring;
+	struct fscrypt_keyring *keyring;
 
 	if (sb->s_master_keys)
 		return 0;
 
-	format_fs_keyring_description(description, sb);
-	keyring = keyring_alloc(description, GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
-				current_cred(), KEY_POS_SEARCH |
-				  KEY_USR_SEARCH | KEY_USR_READ | KEY_USR_VIEW,
-				KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
-	if (IS_ERR(keyring))
-		return PTR_ERR(keyring);
-
+	keyring = kzalloc(sizeof(*keyring), GFP_KERNEL);
+	if (!keyring)
+		return -ENOMEM;
+	spin_lock_init(&keyring->lock);
 	/*
 	 * Pairs with the smp_load_acquire() in fscrypt_find_master_key().
 	 * I.e., here we publish ->s_master_keys with a RELEASE barrier so that
@@ -222,21 +201,80 @@
 	return 0;
 }
 
-void fscrypt_sb_free(struct super_block *sb)
+/*
+ * Release all encryption keys that have been added to the filesystem, along
+ * with the keyring that contains them.
+ *
+ * This is called at unmount time.  The filesystem's underlying block device(s)
+ * are still available at this time; this is important because after user file
+ * accesses have been allowed, this function may need to evict keys from the
+ * keyslots of an inline crypto engine, which requires the block device(s).
+ *
+ * This is also called when the super_block is being freed.  This is needed to
+ * avoid a memory leak if mounting fails after the "test_dummy_encryption"
+ * option was processed, as in that case the unmount-time call isn't made.
+ */
+void fscrypt_destroy_keyring(struct super_block *sb)
 {
-	key_put(sb->s_master_keys);
+	struct fscrypt_keyring *keyring = sb->s_master_keys;
+	size_t i;
+
+	if (!keyring)
+		return;
+
+	for (i = 0; i < ARRAY_SIZE(keyring->key_hashtable); i++) {
+		struct hlist_head *bucket = &keyring->key_hashtable[i];
+		struct fscrypt_master_key *mk;
+		struct hlist_node *tmp;
+
+		hlist_for_each_entry_safe(mk, tmp, bucket, mk_node) {
+			/*
+			 * Since all inodes were already evicted, every key
+			 * remaining in the keyring should have an empty inode
+			 * list, and should only still be in the keyring due to
+			 * the single active ref associated with ->mk_secret.
+			 * There should be no structural refs beyond the one
+			 * associated with the active ref.
+			 */
+			WARN_ON(refcount_read(&mk->mk_active_refs) != 1);
+			WARN_ON(refcount_read(&mk->mk_struct_refs) != 1);
+			WARN_ON(!is_master_key_secret_present(&mk->mk_secret));
+			wipe_master_key_secret(&mk->mk_secret);
+			fscrypt_put_master_key_activeref(mk);
+		}
+	}
+	kfree_sensitive(keyring);
 	sb->s_master_keys = NULL;
 }
 
-/*
- * Find the specified master key in ->s_master_keys.
- * Returns ERR_PTR(-ENOKEY) if not found.
- */
-struct key *fscrypt_find_master_key(struct super_block *sb,
-				    const struct fscrypt_key_specifier *mk_spec)
+static struct hlist_head *
+fscrypt_mk_hash_bucket(struct fscrypt_keyring *keyring,
+		       const struct fscrypt_key_specifier *mk_spec)
 {
-	struct key *keyring;
-	char description[FSCRYPT_MK_DESCRIPTION_SIZE];
+	/*
+	 * Since key specifiers should be "random" values, it is sufficient to
+	 * use a trivial hash function that just takes the first several bits of
+	 * the key specifier.
+	 */
+	unsigned long i = get_unaligned((unsigned long *)&mk_spec->u);
+
+	return &keyring->key_hashtable[i % ARRAY_SIZE(keyring->key_hashtable)];
+}
+
+/*
+ * Find the specified master key struct in ->s_master_keys and take a structural
+ * ref to it.  The structural ref guarantees that the key struct continues to
+ * exist, but it does *not* guarantee that ->s_master_keys continues to contain
+ * the key struct.  The structural ref needs to be dropped by
+ * fscrypt_put_master_key().  Returns NULL if the key struct is not found.
+ */
+struct fscrypt_master_key *
+fscrypt_find_master_key(struct super_block *sb,
+			const struct fscrypt_key_specifier *mk_spec)
+{
+	struct fscrypt_keyring *keyring;
+	struct hlist_head *bucket;
+	struct fscrypt_master_key *mk;
 
 	/*
 	 * Pairs with the smp_store_release() in allocate_filesystem_keyring().
@@ -246,10 +284,38 @@
 	 */
 	keyring = smp_load_acquire(&sb->s_master_keys);
 	if (keyring == NULL)
-		return ERR_PTR(-ENOKEY); /* No keyring yet, so no keys yet. */
+		return NULL; /* No keyring yet, so no keys yet. */
 
-	format_mk_description(description, mk_spec);
-	return search_fscrypt_keyring(keyring, &key_type_fscrypt, description);
+	bucket = fscrypt_mk_hash_bucket(keyring, mk_spec);
+	rcu_read_lock();
+	switch (mk_spec->type) {
+	case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
+		hlist_for_each_entry_rcu(mk, bucket, mk_node) {
+			if (mk->mk_spec.type ==
+				FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
+			    memcmp(mk->mk_spec.u.descriptor,
+				   mk_spec->u.descriptor,
+				   FSCRYPT_KEY_DESCRIPTOR_SIZE) == 0 &&
+			    refcount_inc_not_zero(&mk->mk_struct_refs))
+				goto out;
+		}
+		break;
+	case FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER:
+		hlist_for_each_entry_rcu(mk, bucket, mk_node) {
+			if (mk->mk_spec.type ==
+				FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER &&
+			    memcmp(mk->mk_spec.u.identifier,
+				   mk_spec->u.identifier,
+				   FSCRYPT_KEY_IDENTIFIER_SIZE) == 0 &&
+			    refcount_inc_not_zero(&mk->mk_struct_refs))
+				goto out;
+		}
+		break;
+	}
+	mk = NULL;
+out:
+	rcu_read_unlock();
+	return mk;
 }
 
 static int allocate_master_key_users_keyring(struct fscrypt_master_key *mk)
@@ -277,17 +343,30 @@
 static struct key *find_master_key_user(struct fscrypt_master_key *mk)
 {
 	char description[FSCRYPT_MK_USER_DESCRIPTION_SIZE];
+	key_ref_t keyref;
 
 	format_mk_user_description(description, mk->mk_spec.u.identifier);
-	return search_fscrypt_keyring(mk->mk_users, &key_type_fscrypt_user,
-				      description);
+
+	/*
+	 * We need to mark the keyring reference as "possessed" so that we
+	 * acquire permission to search it, via the KEY_POS_SEARCH permission.
+	 */
+	keyref = keyring_search(make_key_ref(mk->mk_users, true /*possessed*/),
+				&key_type_fscrypt_user, description, false);
+	if (IS_ERR(keyref)) {
+		if (PTR_ERR(keyref) == -EAGAIN || /* not found */
+		    PTR_ERR(keyref) == -EKEYREVOKED) /* recently invalidated */
+			keyref = ERR_PTR(-ENOKEY);
+		return ERR_CAST(keyref);
+	}
+	return key_ref_to_ptr(keyref);
 }
 
 /*
  * Give the current user a "key" in ->mk_users.  This charges the user's quota
  * and marks the master key as added by the current user, so that it cannot be
- * removed by another user with the key.  Either the master key's key->sem must
- * be held for write, or the master key must be still undergoing initialization.
+ * removed by another user with the key.  Either ->mk_sem must be held for
+ * write, or the master key must be still undergoing initialization.
  */
 static int add_master_key_user(struct fscrypt_master_key *mk)
 {
@@ -309,7 +388,7 @@
 
 /*
  * Remove the current user's "key" from ->mk_users.
- * The master key's key->sem must be held for write.
+ * ->mk_sem must be held for write.
  *
  * Returns 0 if removed, -ENOKEY if not found, or another -errno code.
  */
@@ -327,64 +406,49 @@
 }
 
 /*
- * Allocate a new fscrypt_master_key which contains the given secret, set it as
- * the payload of a new 'struct key' of type fscrypt, and link the 'struct key'
- * into the given keyring.  Synchronized by fscrypt_add_key_mutex.
+ * Allocate a new fscrypt_master_key, transfer the given secret over to it, and
+ * insert it into sb->s_master_keys.
  */
-static int add_new_master_key(struct fscrypt_master_key_secret *secret,
-			      const struct fscrypt_key_specifier *mk_spec,
-			      struct key *keyring)
+static int add_new_master_key(struct super_block *sb,
+			      struct fscrypt_master_key_secret *secret,
+			      const struct fscrypt_key_specifier *mk_spec)
 {
+	struct fscrypt_keyring *keyring = sb->s_master_keys;
 	struct fscrypt_master_key *mk;
-	char description[FSCRYPT_MK_DESCRIPTION_SIZE];
-	struct key *key;
 	int err;
 
 	mk = kzalloc(sizeof(*mk), GFP_KERNEL);
 	if (!mk)
 		return -ENOMEM;
 
+	mk->mk_sb = sb;
+	init_rwsem(&mk->mk_sem);
+	refcount_set(&mk->mk_struct_refs, 1);
 	mk->mk_spec = *mk_spec;
 
-	move_master_key_secret(&mk->mk_secret, secret);
-	init_rwsem(&mk->mk_secret_sem);
-
-	refcount_set(&mk->mk_refcount, 1); /* secret is present */
 	INIT_LIST_HEAD(&mk->mk_decrypted_inodes);
 	spin_lock_init(&mk->mk_decrypted_inodes_lock);
 
 	if (mk_spec->type == FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER) {
 		err = allocate_master_key_users_keyring(mk);
 		if (err)
-			goto out_free_mk;
+			goto out_put;
 		err = add_master_key_user(mk);
 		if (err)
-			goto out_free_mk;
+			goto out_put;
 	}
 
-	/*
-	 * Note that we don't charge this key to anyone's quota, since when
-	 * ->mk_users is in use those keys are charged instead, and otherwise
-	 * (when ->mk_users isn't in use) only root can add these keys.
-	 */
-	format_mk_description(description, mk_spec);
-	key = key_alloc(&key_type_fscrypt, description,
-			GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),
-			KEY_POS_SEARCH | KEY_USR_SEARCH | KEY_USR_VIEW,
-			KEY_ALLOC_NOT_IN_QUOTA, NULL);
-	if (IS_ERR(key)) {
-		err = PTR_ERR(key);
-		goto out_free_mk;
-	}
-	err = key_instantiate_and_link(key, mk, sizeof(*mk), keyring, NULL);
-	key_put(key);
-	if (err)
-		goto out_free_mk;
+	move_master_key_secret(&mk->mk_secret, secret);
+	refcount_set(&mk->mk_active_refs, 1); /* ->mk_secret is present */
 
+	spin_lock(&keyring->lock);
+	hlist_add_head_rcu(&mk->mk_node,
+			   fscrypt_mk_hash_bucket(keyring, mk_spec));
+	spin_unlock(&keyring->lock);
 	return 0;
 
-out_free_mk:
-	free_master_key(mk);
+out_put:
+	fscrypt_put_master_key(mk);
 	return err;
 }
 
@@ -393,45 +457,34 @@
 static int add_existing_master_key(struct fscrypt_master_key *mk,
 				   struct fscrypt_master_key_secret *secret)
 {
-	struct key *mk_user;
-	bool rekey;
 	int err;
 
 	/*
 	 * If the current user is already in ->mk_users, then there's nothing to
-	 * do.  (Not applicable for v1 policy keys, which have NULL ->mk_users.)
+	 * do.  Otherwise, we need to add the user to ->mk_users.  (Neither is
+	 * applicable for v1 policy keys, which have NULL ->mk_users.)
 	 */
 	if (mk->mk_users) {
-		mk_user = find_master_key_user(mk);
+		struct key *mk_user = find_master_key_user(mk);
+
 		if (mk_user != ERR_PTR(-ENOKEY)) {
 			if (IS_ERR(mk_user))
 				return PTR_ERR(mk_user);
 			key_put(mk_user);
 			return 0;
 		}
-	}
-
-	/* If we'll be re-adding ->mk_secret, try to take the reference. */
-	rekey = !is_master_key_secret_present(&mk->mk_secret);
-	if (rekey && !refcount_inc_not_zero(&mk->mk_refcount))
-		return KEY_DEAD;
-
-	/* Add the current user to ->mk_users, if applicable. */
-	if (mk->mk_users) {
 		err = add_master_key_user(mk);
-		if (err) {
-			if (rekey && refcount_dec_and_test(&mk->mk_refcount))
-				return KEY_DEAD;
+		if (err)
 			return err;
-		}
 	}
 
 	/* Re-add the secret if needed. */
-	if (rekey) {
-		down_write(&mk->mk_secret_sem);
+	if (!is_master_key_secret_present(&mk->mk_secret)) {
+		if (!refcount_inc_not_zero(&mk->mk_active_refs))
+			return KEY_DEAD;
 		move_master_key_secret(&mk->mk_secret, secret);
-		up_write(&mk->mk_secret_sem);
 	}
+
 	return 0;
 }
 
@@ -440,38 +493,36 @@
 			     const struct fscrypt_key_specifier *mk_spec)
 {
 	static DEFINE_MUTEX(fscrypt_add_key_mutex);
-	struct key *key;
+	struct fscrypt_master_key *mk;
 	int err;
 
 	mutex_lock(&fscrypt_add_key_mutex); /* serialize find + link */
-retry:
-	key = fscrypt_find_master_key(sb, mk_spec);
-	if (IS_ERR(key)) {
-		err = PTR_ERR(key);
-		if (err != -ENOKEY)
-			goto out_unlock;
+
+	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);
-		if (err)
-			goto out_unlock;
-		err = add_new_master_key(secret, mk_spec, sb->s_master_keys);
+		if (!err)
+			err = add_new_master_key(sb, secret, mk_spec);
 	} else {
 		/*
 		 * Found the key in ->s_master_keys.  Re-add the secret if
 		 * needed, and add the user to ->mk_users if needed.
 		 */
-		down_write(&key->sem);
-		err = add_existing_master_key(key->payload.data[0], secret);
-		up_write(&key->sem);
+		down_write(&mk->mk_sem);
+		err = add_existing_master_key(mk, secret);
+		up_write(&mk->mk_sem);
 		if (err == KEY_DEAD) {
-			/* Key being removed or needs to be removed */
-			key_invalidate(key);
-			key_put(key);
-			goto retry;
+			/*
+			 * We found a key struct, but it's already been fully
+			 * removed.  Ignore the old struct and add a new one.
+			 * fscrypt_add_key_mutex means we don't need to worry
+			 * about concurrent adds.
+			 */
+			err = add_new_master_key(sb, secret, mk_spec);
 		}
-		key_put(key);
+		fscrypt_put_master_key(mk);
 	}
-out_unlock:
 	mutex_unlock(&fscrypt_add_key_mutex);
 	return err;
 }
@@ -735,19 +786,19 @@
 			     const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE])
 {
 	struct fscrypt_key_specifier mk_spec;
-	struct key *key, *mk_user;
 	struct fscrypt_master_key *mk;
+	struct key *mk_user;
 	int err;
 
 	mk_spec.type = FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER;
 	memcpy(mk_spec.u.identifier, identifier, FSCRYPT_KEY_IDENTIFIER_SIZE);
 
-	key = fscrypt_find_master_key(sb, &mk_spec);
-	if (IS_ERR(key)) {
-		err = PTR_ERR(key);
+	mk = fscrypt_find_master_key(sb, &mk_spec);
+	if (!mk) {
+		err = -ENOKEY;
 		goto out;
 	}
-	mk = key->payload.data[0];
+	down_read(&mk->mk_sem);
 	mk_user = find_master_key_user(mk);
 	if (IS_ERR(mk_user)) {
 		err = PTR_ERR(mk_user);
@@ -755,7 +806,8 @@
 		key_put(mk_user);
 		err = 0;
 	}
-	key_put(key);
+	up_read(&mk->mk_sem);
+	fscrypt_put_master_key(mk);
 out:
 	if (err == -ENOKEY && capable(CAP_FOWNER))
 		err = 0;
@@ -917,11 +969,10 @@
 	struct super_block *sb = file_inode(filp)->i_sb;
 	struct fscrypt_remove_key_arg __user *uarg = _uarg;
 	struct fscrypt_remove_key_arg arg;
-	struct key *key;
 	struct fscrypt_master_key *mk;
 	u32 status_flags = 0;
 	int err;
-	bool dead;
+	bool inodes_remain;
 
 	if (copy_from_user(&arg, uarg, sizeof(arg)))
 		return -EFAULT;
@@ -941,12 +992,10 @@
 		return -EACCES;
 
 	/* Find the key being removed. */
-	key = fscrypt_find_master_key(sb, &arg.key_spec);
-	if (IS_ERR(key))
-		return PTR_ERR(key);
-	mk = key->payload.data[0];
-
-	down_write(&key->sem);
+	mk = fscrypt_find_master_key(sb, &arg.key_spec);
+	if (!mk)
+		return -ENOKEY;
+	down_write(&mk->mk_sem);
 
 	/* If relevant, remove current user's (or all users) claim to the key */
 	if (mk->mk_users && mk->mk_users->keys.nr_leaves_on_tree != 0) {
@@ -955,7 +1004,7 @@
 		else
 			err = remove_master_key_user(mk);
 		if (err) {
-			up_write(&key->sem);
+			up_write(&mk->mk_sem);
 			goto out_put_key;
 		}
 		if (mk->mk_users->keys.nr_leaves_on_tree != 0) {
@@ -967,28 +1016,22 @@
 			status_flags |=
 				FSCRYPT_KEY_REMOVAL_STATUS_FLAG_OTHER_USERS;
 			err = 0;
-			up_write(&key->sem);
+			up_write(&mk->mk_sem);
 			goto out_put_key;
 		}
 	}
 
 	/* No user claims remaining.  Go ahead and wipe the secret. */
-	dead = false;
+	err = -ENOKEY;
 	if (is_master_key_secret_present(&mk->mk_secret)) {
-		down_write(&mk->mk_secret_sem);
 		wipe_master_key_secret(&mk->mk_secret);
-		dead = refcount_dec_and_test(&mk->mk_refcount);
-		up_write(&mk->mk_secret_sem);
-	}
-	up_write(&key->sem);
-	if (dead) {
-		/*
-		 * No inodes reference the key, and we wiped the secret, so the
-		 * key object is free to be removed from the keyring.
-		 */
-		key_invalidate(key);
+		fscrypt_put_master_key_activeref(mk);
 		err = 0;
-	} else {
+	}
+	inodes_remain = refcount_read(&mk->mk_active_refs) > 0;
+	up_write(&mk->mk_sem);
+
+	if (inodes_remain) {
 		/* Some inodes still reference this key; try to evict them. */
 		err = try_to_lock_encrypted_files(sb, mk);
 		if (err == -EBUSY) {
@@ -1004,7 +1047,7 @@
 	 * has been fully removed including all files locked.
 	 */
 out_put_key:
-	key_put(key);
+	fscrypt_put_master_key(mk);
 	if (err == 0)
 		err = put_user(status_flags, &uarg->removal_status_flags);
 	return err;
@@ -1051,7 +1094,6 @@
 {
 	struct super_block *sb = file_inode(filp)->i_sb;
 	struct fscrypt_get_key_status_arg arg;
-	struct key *key;
 	struct fscrypt_master_key *mk;
 	int err;
 
@@ -1068,19 +1110,18 @@
 	arg.user_count = 0;
 	memset(arg.__out_reserved, 0, sizeof(arg.__out_reserved));
 
-	key = fscrypt_find_master_key(sb, &arg.key_spec);
-	if (IS_ERR(key)) {
-		if (key != ERR_PTR(-ENOKEY))
-			return PTR_ERR(key);
+	mk = fscrypt_find_master_key(sb, &arg.key_spec);
+	if (!mk) {
 		arg.status = FSCRYPT_KEY_STATUS_ABSENT;
 		err = 0;
 		goto out;
 	}
-	mk = key->payload.data[0];
-	down_read(&key->sem);
+	down_read(&mk->mk_sem);
 
 	if (!is_master_key_secret_present(&mk->mk_secret)) {
-		arg.status = FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED;
+		arg.status = refcount_read(&mk->mk_active_refs) > 0 ?
+			FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED :
+			FSCRYPT_KEY_STATUS_ABSENT /* raced with full removal */;
 		err = 0;
 		goto out_release_key;
 	}
@@ -1102,8 +1143,8 @@
 	}
 	err = 0;
 out_release_key:
-	up_read(&key->sem);
-	key_put(key);
+	up_read(&mk->mk_sem);
+	fscrypt_put_master_key(mk);
 out:
 	if (!err && copy_to_user(uarg, &arg, sizeof(arg)))
 		err = -EFAULT;
@@ -1115,13 +1156,9 @@
 {
 	int err;
 
-	err = register_key_type(&key_type_fscrypt);
-	if (err)
-		return err;
-
 	err = register_key_type(&key_type_fscrypt_user);
 	if (err)
-		goto err_unregister_fscrypt;
+		return err;
 
 	err = register_key_type(&key_type_fscrypt_provisioning);
 	if (err)
@@ -1131,7 +1168,5 @@
 
 err_unregister_fscrypt_user:
 	unregister_key_type(&key_type_fscrypt_user);
-err_unregister_fscrypt:
-	unregister_key_type(&key_type_fscrypt);
 	return err;
 }
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index 73d96e3..7b14054 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -9,7 +9,6 @@
  */
 
 #include <crypto/skcipher.h>
-#include <linux/key.h>
 #include <linux/random.h>
 
 #include "fscrypt_private.h"
@@ -151,6 +150,7 @@
 {
 	crypto_free_skcipher(prep_key->tfm);
 	fscrypt_destroy_inline_crypt_key(prep_key);
+	memzero_explicit(prep_key, sizeof(*prep_key));
 }
 
 /* Given a per-file encryption key, set up the file's crypto transform object */
@@ -404,20 +404,18 @@
 /*
  * Find the master key, then set up the inode's actual encryption key.
  *
- * If the master key is found in the filesystem-level keyring, then the
- * corresponding 'struct key' is returned in *master_key_ret with
- * ->mk_secret_sem read-locked.  This is needed to ensure that only one task
- * links the fscrypt_info into ->mk_decrypted_inodes (as multiple tasks may race
- * to create an fscrypt_info for the same inode), and to synchronize the master
- * key being removed with a new inode starting to use it.
+ * If the master key is found in the filesystem-level keyring, then it is
+ * returned in *mk_ret with its semaphore read-locked.  This is needed to ensure
+ * that only one task links the fscrypt_info into ->mk_decrypted_inodes (as
+ * multiple tasks may race to create an fscrypt_info for the same inode), and to
+ * synchronize the master key being removed with a new inode starting to use it.
  */
 static int setup_file_encryption_key(struct fscrypt_info *ci,
 				     bool need_dirhash_key,
-				     struct key **master_key_ret)
+				     struct fscrypt_master_key **mk_ret)
 {
-	struct key *key;
-	struct fscrypt_master_key *mk = NULL;
 	struct fscrypt_key_specifier mk_spec;
+	struct fscrypt_master_key *mk;
 	int err;
 
 	err = fscrypt_select_encryption_impl(ci);
@@ -442,11 +440,10 @@
 		return -EINVAL;
 	}
 
-	key = fscrypt_find_master_key(ci->ci_inode->i_sb, &mk_spec);
-	if (IS_ERR(key)) {
-		if (key != ERR_PTR(-ENOKEY) ||
-		    ci->ci_policy.version != FSCRYPT_POLICY_V1)
-			return PTR_ERR(key);
+	mk = fscrypt_find_master_key(ci->ci_inode->i_sb, &mk_spec);
+	if (!mk) {
+		if (ci->ci_policy.version != FSCRYPT_POLICY_V1)
+			return -ENOKEY;
 
 		/*
 		 * As a legacy fallback for v1 policies, search for the key in
@@ -456,9 +453,7 @@
 		 */
 		return fscrypt_setup_v1_file_key_via_subscribed_keyrings(ci);
 	}
-
-	mk = key->payload.data[0];
-	down_read(&mk->mk_secret_sem);
+	down_read(&mk->mk_sem);
 
 	/* Has the secret been removed (via FS_IOC_REMOVE_ENCRYPTION_KEY)? */
 	if (!is_master_key_secret_present(&mk->mk_secret)) {
@@ -486,18 +481,18 @@
 	if (err)
 		goto out_release_key;
 
-	*master_key_ret = key;
+	*mk_ret = mk;
 	return 0;
 
 out_release_key:
-	up_read(&mk->mk_secret_sem);
-	key_put(key);
+	up_read(&mk->mk_sem);
+	fscrypt_put_master_key(mk);
 	return err;
 }
 
 static void put_crypt_info(struct fscrypt_info *ci)
 {
-	struct key *key;
+	struct fscrypt_master_key *mk;
 
 	if (!ci)
 		return;
@@ -507,24 +502,18 @@
 	else if (ci->ci_owns_key)
 		fscrypt_destroy_prepared_key(&ci->ci_enc_key);
 
-	key = ci->ci_master_key;
-	if (key) {
-		struct fscrypt_master_key *mk = key->payload.data[0];
-
+	mk = ci->ci_master_key;
+	if (mk) {
 		/*
 		 * Remove this inode from the list of inodes that were unlocked
-		 * with the master key.
-		 *
-		 * In addition, if we're removing the last inode from a key that
-		 * already had its secret removed, invalidate the key so that it
-		 * gets removed from ->s_master_keys.
+		 * with the master key.  In addition, if we're removing the last
+		 * inode from a master key struct that already had its secret
+		 * removed, then complete the full removal of the struct.
 		 */
 		spin_lock(&mk->mk_decrypted_inodes_lock);
 		list_del(&ci->ci_master_key_link);
 		spin_unlock(&mk->mk_decrypted_inodes_lock);
-		if (refcount_dec_and_test(&mk->mk_refcount))
-			key_invalidate(key);
-		key_put(key);
+		fscrypt_put_master_key_activeref(mk);
 	}
 	memzero_explicit(ci, sizeof(*ci));
 	kmem_cache_free(fscrypt_info_cachep, ci);
@@ -538,7 +527,7 @@
 {
 	struct fscrypt_info *crypt_info;
 	struct fscrypt_mode *mode;
-	struct key *master_key = NULL;
+	struct fscrypt_master_key *mk = NULL;
 	int res;
 
 	res = fscrypt_initialize(inode->i_sb->s_cop->flags);
@@ -561,8 +550,7 @@
 	WARN_ON(mode->ivsize > FSCRYPT_MAX_IV_SIZE);
 	crypt_info->ci_mode = mode;
 
-	res = setup_file_encryption_key(crypt_info, need_dirhash_key,
-					&master_key);
+	res = setup_file_encryption_key(crypt_info, need_dirhash_key, &mk);
 	if (res)
 		goto out;
 
@@ -577,12 +565,9 @@
 		 * We won the race and set ->i_crypt_info to our crypt_info.
 		 * Now link it into the master key's inode list.
 		 */
-		if (master_key) {
-			struct fscrypt_master_key *mk =
-				master_key->payload.data[0];
-
-			refcount_inc(&mk->mk_refcount);
-			crypt_info->ci_master_key = key_get(master_key);
+		if (mk) {
+			crypt_info->ci_master_key = mk;
+			refcount_inc(&mk->mk_active_refs);
 			spin_lock(&mk->mk_decrypted_inodes_lock);
 			list_add(&crypt_info->ci_master_key_link,
 				 &mk->mk_decrypted_inodes);
@@ -592,11 +577,9 @@
 	}
 	res = 0;
 out:
-	if (master_key) {
-		struct fscrypt_master_key *mk = master_key->payload.data[0];
-
-		up_read(&mk->mk_secret_sem);
-		key_put(master_key);
+	if (mk) {
+		up_read(&mk->mk_sem);
+		fscrypt_put_master_key(mk);
 	}
 	put_crypt_info(crypt_info);
 	return res;
@@ -747,7 +730,6 @@
 int fscrypt_drop_inode(struct inode *inode)
 {
 	const struct fscrypt_info *ci = fscrypt_get_info(inode);
-	const struct fscrypt_master_key *mk;
 
 	/*
 	 * If ci is NULL, then the inode doesn't have an encryption key set up
@@ -757,7 +739,6 @@
 	 */
 	if (!ci || !ci->ci_master_key)
 		return 0;
-	mk = ci->ci_master_key->payload.data[0];
 
 	/*
 	 * With proper, non-racy use of FS_IOC_REMOVE_ENCRYPTION_KEY, all inodes
@@ -769,13 +750,13 @@
 		return 0;
 
 	/*
-	 * Note: since we aren't holding ->mk_secret_sem, the result here can
+	 * Note: since we aren't holding the key semaphore, the result here can
 	 * immediately become outdated.  But there's no correctness problem with
 	 * unnecessarily evicting.  Nor is there a correctness problem with not
 	 * evicting while iput() is racing with the key being removed, since
 	 * then the thread removing the key will either evict the inode itself
 	 * or will correctly detect that it wasn't evicted due to the race.
 	 */
-	return !is_master_key_secret_present(&mk->mk_secret);
+	return !is_master_key_secret_present(&ci->ci_master_key->mk_secret);
 }
 EXPORT_SYMBOL_GPL(fscrypt_drop_inode);
diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c
index faa0f21..f68265c 100644
--- a/fs/crypto/policy.c
+++ b/fs/crypto/policy.c
@@ -686,12 +686,8 @@
 	 * delayed key setup that requires the inode number.
 	 */
 	if (ci->ci_policy.version == FSCRYPT_POLICY_V2 &&
-	    (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) {
-		const struct fscrypt_master_key *mk =
-			ci->ci_master_key->payload.data[0];
-
-		fscrypt_hash_inode_number(ci, mk);
-	}
+	    (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32))
+		fscrypt_hash_inode_number(ci, ci->ci_master_key);
 
 	return inode->i_sb->s_cop->set_context(inode, &ctx, ctxsize, fs_data);
 }