ext4 crypto: use slab caches

Use slab caches the ext4_crypto_ctx and ext4_crypt_info structures for
slighly better memory efficiency and debuggability.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/crypto.c

@@ -55,6 +55,9 @@ static mempool_t *ext4_bounce_page_pool;
 static LIST_HEAD(ext4_free_crypto_ctxs);
 static DEFINE_SPINLOCK(ext4_crypto_ctx_lock);
 
+static struct kmem_cache *ext4_crypto_ctx_cachep;
+struct kmem_cache *ext4_crypt_info_cachep;
+
 /**
  * ext4_release_crypto_ctx() - Releases an encryption context
  * @ctx: The encryption context to release.
@@ -79,7 +82,7 @@ void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx)
 	if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {
 		if (ctx->tfm)
 			crypto_free_tfm(ctx->tfm);
-		kfree(ctx);
+		kmem_cache_free(ext4_crypto_ctx_cachep, ctx);
 	} else {
 		spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
 		list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
@@ -87,23 +90,6 @@ void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx)
 	}
 }
 
-/**
- * ext4_alloc_and_init_crypto_ctx() - Allocates and inits an encryption context
- * @mask: The allocation mask.
- *
- * Return: An allocated and initialized encryption context on success. An error
- * value or NULL otherwise.
- */
-static struct ext4_crypto_ctx *ext4_alloc_and_init_crypto_ctx(gfp_t mask)
-{
-	struct ext4_crypto_ctx *ctx = kzalloc(sizeof(struct ext4_crypto_ctx),
-					      mask);
-
-	if (!ctx)
-		return ERR_PTR(-ENOMEM);
-	return ctx;
-}
-
 /**
  * ext4_get_crypto_ctx() - Gets an encryption context
  * @inode:       The inode for which we are doing the crypto
@@ -121,8 +107,6 @@ struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode)
 	struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
 
 	BUG_ON(ci == NULL);
-	if (!ext4_read_workqueue)
-		ext4_init_crypto();
 
 	/*
 	 * We first try getting the ctx from a free list because in
@@ -141,9 +125,9 @@ struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode)
 		list_del(&ctx->free_list);
 	spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
 	if (!ctx) {
-		ctx = ext4_alloc_and_init_crypto_ctx(GFP_NOFS);
-		if (IS_ERR(ctx)) {
-			res = PTR_ERR(ctx);
+		ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS);
+		if (!ctx) {
+			res = -ENOMEM;
 			goto out;
 		}
 		ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
@@ -217,7 +201,7 @@ void ext4_exit_crypto(void)
 		}
 		if (pos->tfm)
 			crypto_free_tfm(pos->tfm);
-		kfree(pos);
+		kmem_cache_free(ext4_crypto_ctx_cachep, pos);
 	}
 	INIT_LIST_HEAD(&ext4_free_crypto_ctxs);
 	if (ext4_bounce_page_pool)
@@ -226,6 +210,12 @@ void ext4_exit_crypto(void)
 	if (ext4_read_workqueue)
 		destroy_workqueue(ext4_read_workqueue);
 	ext4_read_workqueue = NULL;
+	if (ext4_crypto_ctx_cachep)
+		kmem_cache_destroy(ext4_crypto_ctx_cachep);
+	ext4_crypto_ctx_cachep = NULL;
+	if (ext4_crypt_info_cachep)
+		kmem_cache_destroy(ext4_crypt_info_cachep);
+	ext4_crypt_info_cachep = NULL;
 }
 
 /**
@@ -238,23 +228,31 @@ void ext4_exit_crypto(void)
  */
 int ext4_init_crypto(void)
 {
-	int i, res;
+	int i, res = -ENOMEM;
 
 	mutex_lock(&crypto_init);
 	if (ext4_read_workqueue)
 		goto already_initialized;
 	ext4_read_workqueue = alloc_workqueue("ext4_crypto", WQ_HIGHPRI, 0);
-	if (!ext4_read_workqueue) {
-		res = -ENOMEM;
+	if (!ext4_read_workqueue)
+		goto fail;
+
+	ext4_crypto_ctx_cachep = KMEM_CACHE(ext4_crypto_ctx,
+					    SLAB_RECLAIM_ACCOUNT);
+	if (!ext4_crypto_ctx_cachep)
+		goto fail;
+
+	ext4_crypt_info_cachep = KMEM_CACHE(ext4_crypt_info,
+					    SLAB_RECLAIM_ACCOUNT);
+	if (!ext4_crypt_info_cachep)
 		goto fail;
-	}
 
 	for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
 		struct ext4_crypto_ctx *ctx;
 
-		ctx = ext4_alloc_and_init_crypto_ctx(GFP_KERNEL);
-		if (IS_ERR(ctx)) {
-			res = PTR_ERR(ctx);
+		ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS);
+		if (!ctx) {
+			res = -ENOMEM;
 			goto fail;
 		}
 		list_add(&ctx->free_list, &ext4_free_crypto_ctxs);

fs/ext4/crypto_key.c

@@ -96,7 +96,7 @@ void ext4_free_encryption_info(struct inode *inode)
 		key_put(ci->ci_keyring_key);
 	crypto_free_ablkcipher(ci->ci_ctfm);
 	memzero_explicit(&ci->ci_raw, sizeof(ci->ci_raw));
-	kfree(ci);
+	kmem_cache_free(ext4_crypt_info_cachep, ci);
 	ei->i_crypt_info = NULL;
 }
 
@@ -113,6 +113,12 @@ int _ext4_get_encryption_info(struct inode *inode)
 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 	int res;
 
+	if (!ext4_read_workqueue) {
+		res = ext4_init_crypto();
+		if (res)
+			return res;
+	}
+
 	if (ei->i_crypt_info) {
 		if (!ei->i_crypt_info->ci_keyring_key ||
 		    key_validate(ei->i_crypt_info->ci_keyring_key) == 0)
@@ -134,7 +140,7 @@ int _ext4_get_encryption_info(struct inode *inode)
 		return -EINVAL;
 	res = 0;
 
-	crypt_info = kmalloc(sizeof(struct ext4_crypt_info), GFP_KERNEL);
+	crypt_info = kmem_cache_alloc(ext4_crypt_info_cachep, GFP_KERNEL);
 	if (!crypt_info)
 		return -ENOMEM;
 
@@ -188,7 +194,7 @@ out:
 	if (res < 0) {
 		if (res == -ENOKEY)
 			res = 0;
-		kfree(crypt_info);
+		kmem_cache_free(ext4_crypt_info_cachep, crypt_info);
 	} else {
 		ei->i_crypt_info = crypt_info;
 		crypt_info->ci_keyring_key = keyring_key;

fs/ext4/ext4.h

@@ -2059,6 +2059,7 @@ int ext4_get_policy(struct inode *inode,
 		    struct ext4_encryption_policy *policy);
 
 /* crypto.c */
+extern struct kmem_cache *ext4_crypt_info_cachep;
 bool ext4_valid_contents_enc_mode(uint32_t mode);
 uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size);
 extern struct workqueue_struct *ext4_read_workqueue;