[PATCH] fscrypt: introduce fscrypt_needs_contents_encryption()

[PATCH] fscrypt: introduce fscrypt_needs_contents_encryption()

[Eric Biggers]

From: Eric Biggers <ebiggers@google.com>

Add a function fscrypt_needs_contents_encryption() which takes an inode
and returns true if it's an encrypted regular file and the kernel was
built with fscrypt support.

This will allow replacing duplicated checks of IS_ENCRYPTED() &&
S_ISREG() on the I/O paths in ext4 and f2fs, while also optimizing out
unneeded code when !CONFIG_FS_ENCRYPTION.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 include/linux/fscrypt.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index cb18b5fbcef92..2a29f56b1a1cb 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -72,6 +72,21 @@ static inline bool fscrypt_has_encryption_key(const struct inode *inode)
 	return READ_ONCE(inode->i_crypt_info) != NULL;
 }
 
+/**
+ * fscrypt_needs_contents_encryption() - check whether an inode needs
+ *					 contents encryption
+ *
+ * Return: %true iff the inode is an encrypted regular file and the kernel was
+ * built with fscrypt support.
+ *
+ * If you need to know whether the encrypt bit is set even when the kernel was
+ * built without fscrypt support, you must use IS_ENCRYPTED() directly instead.
+ */
+static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
+{
+	return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
+}
+
 static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
 {
 	return inode->i_sb->s_cop->dummy_context &&
@@ -269,6 +284,11 @@ static inline bool fscrypt_has_encryption_key(const struct inode *inode)
 	return false;
 }
 
+static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
+{
+	return false;
+}
+
 static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
 {
 	return false;
-- 
2.24.0.393.g34dc348eaf-goog

Re: [PATCH] fscrypt: introduce fscrypt_needs_contents_encryption()

[Eric Biggers]

On Mon, Dec 09, 2019 at 12:50:21PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
> 
> Add a function fscrypt_needs_contents_encryption() which takes an inode
> and returns true if it's an encrypted regular file and the kernel was
> built with fscrypt support.
> 
> This will allow replacing duplicated checks of IS_ENCRYPTED() &&
> S_ISREG() on the I/O paths in ext4 and f2fs, while also optimizing out
> unneeded code when !CONFIG_FS_ENCRYPTION.
> 
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>  include/linux/fscrypt.h | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
> index cb18b5fbcef92..2a29f56b1a1cb 100644
> --- a/include/linux/fscrypt.h
> +++ b/include/linux/fscrypt.h
> @@ -72,6 +72,21 @@ static inline bool fscrypt_has_encryption_key(const struct inode *inode)
>  	return READ_ONCE(inode->i_crypt_info) != NULL;
>  }
>  
> +/**
> + * fscrypt_needs_contents_encryption() - check whether an inode needs
> + *					 contents encryption
> + *
> + * Return: %true iff the inode is an encrypted regular file and the kernel was
> + * built with fscrypt support.
> + *
> + * If you need to know whether the encrypt bit is set even when the kernel was
> + * built without fscrypt support, you must use IS_ENCRYPTED() directly instead.
> + */
> +static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
> +{
> +	return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
> +}
> +
>  static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
>  {
>  	return inode->i_sb->s_cop->dummy_context &&
> @@ -269,6 +284,11 @@ static inline bool fscrypt_has_encryption_key(const struct inode *inode)
>  	return false;
>  }
>  
> +static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
> +{
> +	return false;
> +}
> +
>  static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
>  {
>  	return false;
> -- 
> 2.24.0.393.g34dc348eaf-goog
> 

Applied to fscrypt.git#master for 5.6.

- Eric