[02/26] fscrypto: Constify struct inode pointer

Commit Message

Richard Weinberger Oct. 21, 2016, 12:48 p.m. UTC

Some filesystems, such as UBIFS, maintain a const pointer
for struct inode.

Signed-off-by: Richard Weinberger <[e-mail]>
---
 fs/crypto/crypto.c       | 12 +++++++-----
 include/linux/fscrypto.h | 12 +++++++-----
 2 files changed, 14 insertions(+), 10 deletions(-)

Comments

Theodore Ts'o Oct. 21, 2016, 2:57 p.m. UTC | #1

On Fri, Oct 21, 2016 at 02:48:17PM +0200, Richard Weinberger wrote:
> Some filesystems, such as UBIFS, maintain a const pointer
> for struct inode.
> 
>  /* fname.c */
> -extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
> -				int lookup, struct fscrypt_name *);
> +extern int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
> +			   int lookup, struct fscrypt_name *fname);

Was it deliberate that you didn't add a const pointer here?

I take it that ubifs is basically using const in certain places to
essentially promise that those functions don't actually modify the
inode structure?

							- Ted
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Richard Weinberger Oct. 21, 2016, 3:10 p.m. UTC | #2

Ted,

On 21.10.2016 16:57, Theodore Ts'o wrote:
> On Fri, Oct 21, 2016 at 02:48:17PM +0200, Richard Weinberger wrote:
>> Some filesystems, such as UBIFS, maintain a const pointer
>> for struct inode.
>>
>>  /* fname.c */
>> -extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
>> -				int lookup, struct fscrypt_name *);
>> +extern int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
>> +			   int lookup, struct fscrypt_name *fname);
> 
> Was it deliberate that you didn't add a const pointer here?

Erm, no. Either I forgot or while rebasing my mess to something
sane the change got lost.

> I take it that ubifs is basically using const in certain places to
> essentially promise that those functions don't actually modify the
> inode structure?

Yes.

Thanks,
//richard
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Patch

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 1c2f9516b4be..8c59912feebb 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -147,7 +147,7 @@  typedef enum {
 	FS_ENCRYPT,
 } fscrypt_direction_t;
 
-static int do_crypto(struct inode *inode,
+static int do_crypto(const struct inode *inode,
 		     fscrypt_direction_t rw, pgoff_t index,
 		     struct scatterlist *src, struct scatterlist *dst,
 		     unsigned int cryptlen, gfp_t gfp_flags)
@@ -212,7 +212,7 @@  static int do_page_crypto(struct inode *inode,
 	return do_crypto(inode, rw, index, &src, &dst, PAGE_SIZE, gfp_flags);
 }
 
-static int do_buf_crypto(struct inode *inode,
+static int do_buf_crypto(const struct inode *inode,
 			 fscrypt_direction_t rw, pgoff_t index,
 			 const void *src_buf, const void *dst_buf,
 			 unsigned int buflen, gfp_t gfp_flags)
@@ -287,7 +287,7 @@  errout:
 }
 EXPORT_SYMBOL(fscrypt_encrypt_page);
 
-int fscrypt_encrypt_buffer(struct inode *inode, const void *plaintext_buf,
+int fscrypt_encrypt_buffer(const struct inode *inode, const void *plaintext_buf,
 			   const void *ciphertext_buf, unsigned int buflen,
 			   pgoff_t index, gfp_t gfp_flags)
 {
@@ -296,8 +296,10 @@  int fscrypt_encrypt_buffer(struct inode *inode, const void *plaintext_buf,
 }
 EXPORT_SYMBOL(fscrypt_encrypt_buffer);
 
-int fscrypt_decrypt_buffer(struct inode *inode, const void *ciphertext_buf,
-			   const void *plaintext_buf, unsigned int buflen,
+int fscrypt_decrypt_buffer(const struct inode *inode,
+			   const void *ciphertext_buf,
+			   const void *plaintext_buf,
+			   unsigned int buflen,
 			   pgoff_t index, gfp_t gfp_flags)
 {
 	return do_buf_crypto(inode, FS_DECRYPT, index, ciphertext_buf,
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index a9628b4882e7..d18ee29cf69a 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -273,11 +273,13 @@  extern void fscrypt_pullback_bio_page(struct page **, bool);
 extern void fscrypt_restore_control_page(struct page *);
 extern int fscrypt_zeroout_range(struct inode *, pgoff_t, sector_t,
 						unsigned int);
-int fscrypt_encrypt_buffer(struct inode *inode, const void *plaintext_buf,
+int fscrypt_encrypt_buffer(const struct inode *inode, const void *plaintext_buf,
 			   const void *ciphertext_buf, unsigned int buflen,
 			   pgoff_t index, gfp_t gfp_flags);
-int fscrypt_decrypt_buffer(struct inode *inode, const void *ciphertext_buf,
-			   const void *plaintext_buf, unsigned int buflen,
+int fscrypt_decrypt_buffer(const struct inode *inode,
+			   const void *ciphertext_buf,
+			   const void *plaintext_buf,
+			   unsigned int buflen,
 			   pgoff_t index, gfp_t gfp_flags);
 /* policy.c */
 extern int fscrypt_process_policy(struct file *, const struct fscrypt_policy *);
@@ -291,8 +293,8 @@  extern int fscrypt_get_encryption_info(struct inode *);
 extern void fscrypt_put_encryption_info(struct inode *, struct fscrypt_info *);
 
 /* fname.c */
-extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
-				int lookup, struct fscrypt_name *);
+extern int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname,
+			   int lookup, struct fscrypt_name *fname);
 extern void fscrypt_free_filename(struct fscrypt_name *);
 extern u32 fscrypt_fname_encrypted_size(struct inode *, u32);
 extern int fscrypt_fname_alloc_buffer(struct inode *, u32,