fscrypt: Add in-place encryption mode
ext4 and f2fs require a bounce page when encrypting pages. However, not
all filesystems will need that (eg. UBIFS). This is handled via a
flag on fscrypt_operations where a fs implementation can select in-place
encryption over using a bounce page (which is the default).
Signed-off-by: David Gstir <david@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 98f87fe..f38dc8a 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -217,8 +217,9 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
* @plaintext_page: The page to encrypt. Must be locked.
* @gfp_flags: The gfp flag for memory allocation
*
- * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
- * encryption context.
+ * Encrypts plaintext_page using the ctx encryption context. If
+ * the filesystem supports it, encryption is performed in-place, otherwise a
+ * new ciphertext_page is allocated and returned.
*
* Called on the page write path. The caller must call
* fscrypt_restore_control_page() on the returned ciphertext page to
@@ -231,7 +232,7 @@ struct page *fscrypt_encrypt_page(struct inode *inode,
struct page *plaintext_page, gfp_t gfp_flags)
{
struct fscrypt_ctx *ctx;
- struct page *ciphertext_page = NULL;
+ struct page *ciphertext_page = plaintext_page;
int err;
BUG_ON(!PageLocked(plaintext_page));
@@ -240,10 +241,12 @@ struct page *fscrypt_encrypt_page(struct inode *inode,
if (IS_ERR(ctx))
return (struct page *)ctx;
- /* The encryption operation will require a bounce page. */
- ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
- if (IS_ERR(ciphertext_page))
- goto errout;
+ if (!(inode->i_sb->s_cop->flags & FS_CFLG_INPLACE_ENCRYPTION)) {
+ /* The encryption operation will require a bounce page. */
+ ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
+ if (IS_ERR(ciphertext_page))
+ goto errout;
+ }
ctx->w.control_page = plaintext_page;
err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
@@ -253,9 +256,11 @@ struct page *fscrypt_encrypt_page(struct inode *inode,
ciphertext_page = ERR_PTR(err);
goto errout;
}
- SetPagePrivate(ciphertext_page);
- set_page_private(ciphertext_page, (unsigned long)ctx);
- lock_page(ciphertext_page);
+ if (!(inode->i_sb->s_cop->flags & FS_CFLG_INPLACE_ENCRYPTION)) {
+ SetPagePrivate(ciphertext_page);
+ set_page_private(ciphertext_page, (unsigned long)ctx);
+ lock_page(ciphertext_page);
+ }
return ciphertext_page;
errout: