eCryptfs: Merge ecryptfs_encrypt_extent() and ecryptfs_decrypt_extent()

They are identical except if the src_page or dst_page index is used, so
they can be merged safely if page_index is conditionally assigned.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 609efc0..9845d2f 100644 (file)
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -416,28 +416,29 @@ static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
 }
 
 /**
- * ecryptfs_encrypt_extent
- * @enc_extent_page: Allocated page into which to encrypt the data in
- *                   @page
+ * crypt_extent
+ * @dst_page: The page to write the result into
  * @crypt_stat: crypt_stat containing cryptographic context for the
  *              encryption operation
- * @page: Page containing plaintext data extent to encrypt
+ * @src_page: The page to read from
  * @extent_offset: Page extent offset for use in generating IV
+ * @op: ENCRYPT or DECRYPT to indicate the desired operation
  *
- * Encrypts one extent of data.
+ * Encrypts or decrypts one extent of data.
  *
  * Return zero on success; non-zero otherwise
  */
-static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
-                                  struct ecryptfs_crypt_stat *crypt_stat,
-                                  struct page *page,
-                                  unsigned long extent_offset)
+static int crypt_extent(struct page *dst_page,
+                       struct ecryptfs_crypt_stat *crypt_stat,
+                       struct page *src_page,
+                       unsigned long extent_offset, int op)
 {
+       pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
        loff_t extent_base;
        char extent_iv[ECRYPTFS_MAX_IV_BYTES];
        int rc;
 
-       extent_base = (((loff_t)page->index)
+       extent_base = (((loff_t)page_index)
                       * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
        rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
                                (extent_base + extent_offset));
@@ -447,14 +448,13 @@ static int ecryptfs_encrypt_extent(struct page *enc_extent_page,
                        (unsigned long long)(extent_base + extent_offset), rc);
                goto out;
        }
-       rc = crypt_page_offset(crypt_stat, enc_extent_page, page,
+       rc = crypt_page_offset(crypt_stat, dst_page, src_page,
                               (extent_offset * crypt_stat->extent_size),
-                              crypt_stat->extent_size, extent_iv, ENCRYPT);
+                              crypt_stat->extent_size, extent_iv, op);
        if (rc < 0) {
-               printk(KERN_ERR "%s: Error attempting to encrypt page with "
-                      "page->index = [%ld], extent_offset = [%ld]; "
-                      "rc = [%d]\n", __func__, page->index, extent_offset,
-                      rc);
+               printk(KERN_ERR "%s: Error attempting to crypt page with "
+                      "page_index = [%ld], extent_offset = [%ld]; "
+                      "rc = [%d]\n", __func__, page_index, extent_offset, rc);
                goto out;
        }
        rc = 0;
@@ -503,8 +503,8 @@ int ecryptfs_encrypt_page(struct page *page)
        for (extent_offset = 0;
             extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
             extent_offset++) {
-               rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
-                                            extent_offset);
+               rc = crypt_extent(enc_extent_page, crypt_stat, page,
+                                 extent_offset, ENCRYPT);
                if (rc) {
                        printk(KERN_ERR "%s: Error encrypting extent; "
                               "rc = [%d]\n", __func__, rc);
@@ -531,40 +531,6 @@ out:
        return rc;
 }
 
-static int ecryptfs_decrypt_extent(struct page *page,
-                                  struct ecryptfs_crypt_stat *crypt_stat,
-                                  struct page *enc_extent_page,
-                                  unsigned long extent_offset)
-{
-       loff_t extent_base;
-       char extent_iv[ECRYPTFS_MAX_IV_BYTES];
-       int rc;
-
-       extent_base = (((loff_t)page->index)
-                      * (PAGE_CACHE_SIZE / crypt_stat->extent_size));
-       rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
-                               (extent_base + extent_offset));
-       if (rc) {
-               ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
-                       "extent [0x%.16llx]; rc = [%d]\n",
-                       (unsigned long long)(extent_base + extent_offset), rc);
-               goto out;
-       }
-       rc = crypt_page_offset(crypt_stat, page, enc_extent_page,
-                              (extent_offset * crypt_stat->extent_size),
-                              crypt_stat->extent_size, extent_iv, DECRYPT);
-       if (rc < 0) {
-               printk(KERN_ERR "%s: Error attempting to decrypt to page with "
-                      "page->index = [%ld], extent_offset = [%ld]; "
-                      "rc = [%d]\n", __func__, page->index, extent_offset,
-                      rc);
-               goto out;
-       }
-       rc = 0;
-out:
-       return rc;
-}
-
 /**
  * ecryptfs_decrypt_page
  * @page: Page mapped from the eCryptfs inode for the file; data read
@@ -610,8 +576,8 @@ int ecryptfs_decrypt_page(struct page *page)
        for (extent_offset = 0;
             extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
             extent_offset++) {
-               rc = ecryptfs_decrypt_extent(page, crypt_stat, page,
-                                            extent_offset);
+               rc = crypt_extent(page, crypt_stat, page,
+                                 extent_offset, DECRYPT);
                if (rc) {
                        printk(KERN_ERR "%s: Error encrypting extent; "
                               "rc = [%d]\n", __func__, rc);