fscrypt: replace raw loads of info pointer with helper function

Add and use a helper function fscrypt_get_inode_info_raw().  It loads an
inode's fscrypt info pointer using a raw dereference, which is
appropriate when the caller knows the key setup already happened.

This eliminates most occurrences of inode::i_crypt_info in the source,
in preparation for replacing that with a filesystem-specific field.

Co-developed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Link: https://lore.kernel.org/20250810075706.172910-2-ebiggers@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/crypto/bio.c

@@ -113,7 +113,7 @@ out:
 int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 			  sector_t pblk, unsigned int len)
 {
-	const struct fscrypt_inode_info *ci = inode->i_crypt_info;
+	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
 	const unsigned int du_bits = ci->ci_data_unit_bits;
 	const unsigned int du_size = 1U << du_bits;
 	const unsigned int du_per_page_bits = PAGE_SHIFT - du_bits;

fs/crypto/crypto.c

@@ -173,7 +173,7 @@ struct page *fscrypt_encrypt_pagecache_blocks(struct folio *folio,
 		size_t len, size_t offs, gfp_t gfp_flags)
 {
 	const struct inode *inode = folio->mapping->host;
-	const struct fscrypt_inode_info *ci = inode->i_crypt_info;
+	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
 	const unsigned int du_bits = ci->ci_data_unit_bits;
 	const unsigned int du_size = 1U << du_bits;
 	struct page *ciphertext_page;
@@ -232,8 +232,9 @@ int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
 {
 	if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))
 		return -EOPNOTSUPP;
-	return fscrypt_crypt_data_unit(inode->i_crypt_info, FS_ENCRYPT,
+	return fscrypt_crypt_data_unit(fscrypt_get_inode_info_raw(inode),
-				       lblk_num, page, page, len, offs);
+				       FS_ENCRYPT, lblk_num, page, page, len,
+				       offs);
 }
 EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
 
@@ -255,7 +256,7 @@ int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len,
 				     size_t offs)
 {
 	const struct inode *inode = folio->mapping->host;
-	const struct fscrypt_inode_info *ci = inode->i_crypt_info;
+	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
 	const unsigned int du_bits = ci->ci_data_unit_bits;
 	const unsigned int du_size = 1U << du_bits;
 	u64 index = ((u64)folio->index << (PAGE_SHIFT - du_bits)) +
@@ -305,8 +306,9 @@ int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
 {
 	if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))
 		return -EOPNOTSUPP;
-	return fscrypt_crypt_data_unit(inode->i_crypt_info, FS_DECRYPT,
+	return fscrypt_crypt_data_unit(fscrypt_get_inode_info_raw(inode),
-				       lblk_num, page, page, len, offs);
+				       FS_DECRYPT, lblk_num, page, page, len,
+				       offs);
 }
 EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
 

fs/crypto/fname.c

@@ -94,7 +94,7 @@ static inline bool fscrypt_is_dot_dotdot(const struct qstr *str)
 int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
 			  u8 *out, unsigned int olen)
 {
-	const struct fscrypt_inode_info *ci = inode->i_crypt_info;
+	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
 	struct crypto_sync_skcipher *tfm = ci->ci_enc_key.tfm;
 	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
 	union fscrypt_iv iv;
@@ -138,7 +138,7 @@ static int fname_decrypt(const struct inode *inode,
 			 const struct fscrypt_str *iname,
 			 struct fscrypt_str *oname)
 {
-	const struct fscrypt_inode_info *ci = inode->i_crypt_info;
+	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
 	struct crypto_sync_skcipher *tfm = ci->ci_enc_key.tfm;
 	SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm);
 	union fscrypt_iv iv;
@@ -274,8 +274,9 @@ bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy,
 bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
 				  u32 max_len, u32 *encrypted_len_ret)
 {
-	return __fscrypt_fname_encrypted_size(&inode->i_crypt_info->ci_policy,
+	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
-					      orig_len, max_len,
+
+	return __fscrypt_fname_encrypted_size(&ci->ci_policy, orig_len, max_len,
 					      encrypted_len_ret);
 }
 EXPORT_SYMBOL_GPL(fscrypt_fname_encrypted_size);
@@ -543,7 +544,7 @@ EXPORT_SYMBOL_GPL(fscrypt_match_name);
  */
 u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name)
 {
-	const struct fscrypt_inode_info *ci = dir->i_crypt_info;
+	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(dir);
 
 	WARN_ON_ONCE(!ci->ci_dirhash_key_initialized);
 

fs/crypto/hooks.c

@@ -199,7 +199,7 @@ int fscrypt_prepare_setflags(struct inode *inode,
 		err = fscrypt_require_key(inode);
 		if (err)
 			return err;
-		ci = inode->i_crypt_info;
+		ci = fscrypt_get_inode_info_raw(inode);
 		if (ci->ci_policy.version != FSCRYPT_POLICY_V2)
 			return -EINVAL;
 		mk = ci->ci_master_key;

fs/crypto/inline_crypt.c

@@ -263,7 +263,7 @@ int fscrypt_derive_sw_secret(struct super_block *sb,
 
 bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
 {
-	return inode->i_crypt_info->ci_inlinecrypt;
+	return fscrypt_get_inode_info_raw(inode)->ci_inlinecrypt;
 }
 EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto);
 
@@ -307,7 +307,7 @@ void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode,
 
 	if (!fscrypt_inode_uses_inline_crypto(inode))
 		return;
-	ci = inode->i_crypt_info;
+	ci = fscrypt_get_inode_info_raw(inode);
 
 	fscrypt_generate_dun(ci, first_lblk, dun);
 	bio_crypt_set_ctx(bio, ci->ci_enc_key.blk_key, dun, gfp_mask);
@@ -385,22 +385,24 @@ bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
 			   u64 next_lblk)
 {
 	const struct bio_crypt_ctx *bc = bio->bi_crypt_context;
+	const struct fscrypt_inode_info *ci;
 	u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
 
 	if (!!bc != fscrypt_inode_uses_inline_crypto(inode))
 		return false;
 	if (!bc)
 		return true;
+	ci = fscrypt_get_inode_info_raw(inode);
 
 	/*
 	 * Comparing the key pointers is good enough, as all I/O for each key
 	 * uses the same pointer.  I.e., there's currently no need to support
 	 * merging requests where the keys are the same but the pointers differ.
 	 */
-	if (bc->bc_key != inode->i_crypt_info->ci_enc_key.blk_key)
+	if (bc->bc_key != ci->ci_enc_key.blk_key)
 		return false;
 
-	fscrypt_generate_dun(inode->i_crypt_info, next_lblk, next_dun);
+	fscrypt_generate_dun(ci, next_lblk, next_dun);
 	return bio_crypt_dun_is_contiguous(bc, bio->bi_iter.bi_size, next_dun);
 }
 EXPORT_SYMBOL_GPL(fscrypt_mergeable_bio);
@@ -502,7 +504,7 @@ u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks)
 	if (nr_blocks <= 1)
 		return nr_blocks;
 
-	ci = inode->i_crypt_info;
+	ci = fscrypt_get_inode_info_raw(inode);
 	if (!(fscrypt_policy_flags(&ci->ci_policy) &
 	      FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32))
 		return nr_blocks;

fs/crypto/policy.c

@@ -727,7 +727,7 @@ const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir)
 		err = fscrypt_require_key(dir);
 		if (err)
 			return ERR_PTR(err);
-		return &dir->i_crypt_info->ci_policy;
+		return &fscrypt_get_inode_info_raw(dir)->ci_policy;
 	}
 
 	return fscrypt_get_dummy_policy(dir->i_sb);
@@ -746,7 +746,7 @@ const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir)
  */
 int fscrypt_context_for_new_inode(void *ctx, struct inode *inode)
 {
-	struct fscrypt_inode_info *ci = inode->i_crypt_info;
+	struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode);
 
 	BUILD_BUG_ON(sizeof(union fscrypt_context) !=
 			FSCRYPT_SET_CONTEXT_MAX_SIZE);
@@ -771,7 +771,7 @@ EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode);
  */
 int fscrypt_set_context(struct inode *inode, void *fs_data)
 {
-	struct fscrypt_inode_info *ci = inode->i_crypt_info;
+	struct fscrypt_inode_info *ci;
 	union fscrypt_context ctx;
 	int ctxsize;
 
@@ -783,6 +783,7 @@ int fscrypt_set_context(struct inode *inode, void *fs_data)
 	 * This may be the first time the inode number is available, so do any
 	 * delayed key setup that requires the inode number.
 	 */
+	ci = fscrypt_get_inode_info_raw(inode);
 	if (ci->ci_policy.version == FSCRYPT_POLICY_V2 &&
 	    (ci->ci_policy.v2.flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32))
 		fscrypt_hash_inode_number(ci, ci->ci_master_key);

include/linux/fscrypt.h

@@ -195,6 +195,22 @@ struct fscrypt_operations {
 int fscrypt_d_revalidate(struct inode *dir, const struct qstr *name,
 			 struct dentry *dentry, unsigned int flags);
 
+/*
+ * Load the inode's fscrypt info pointer, using a raw dereference.  Since this
+ * uses a raw dereference with no memory barrier, it is appropriate to use only
+ * when the caller knows the inode's key setup already happened, resulting in
+ * non-NULL fscrypt info.  E.g., the file contents en/decryption functions use
+ * this, since fscrypt_file_open() set up the key.
+ */
+static inline struct fscrypt_inode_info *
+fscrypt_get_inode_info_raw(const struct inode *inode)
+{
+	struct fscrypt_inode_info *ci = inode->i_crypt_info;
+
+	VFS_WARN_ON_ONCE(ci == NULL);
+	return ci;
+}
+
 static inline struct fscrypt_inode_info *
 fscrypt_get_inode_info(const struct inode *inode)
 {