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>

1 files changed, 20 insertions, 54 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 609efc01d5c2..9845d2fd2506 100644
--- 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);