eCryptfs: Read/write entire page during page IO

When reading and writing encrypted pages, perform IO using the entire
page all at once rather than 4096 bytes at a time.

This only affects architectures where PAGE_CACHE_SIZE is larger than
4096 bytes.

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

1 files changed, 31 insertions, 35 deletions

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index e8976c004669..4185584594f5 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -490,6 +490,7 @@ int ecryptfs_encrypt_page(struct page *page)
         char *enc_extent_virt;
         struct page *enc_extent_page = NULL;
         loff_t extent_offset;
+        loff_t lower_offset;
         int rc = 0;
 
         ecryptfs_inode = page->mapping->host;
@@ -503,12 +504,10 @@ int ecryptfs_encrypt_page(struct page *page)
                                 "encrypted extent\n");
                 goto out;
         }
-        enc_extent_virt = kmap(enc_extent_page);
+
         for (extent_offset = 0;
              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
              extent_offset++) {
-                loff_t offset;
-
                 rc = ecryptfs_encrypt_extent(enc_extent_page, crypt_stat, page,
                                              extent_offset);
                 if (rc) {
@@ -516,25 +515,24 @@ int ecryptfs_encrypt_page(struct page *page)
                                "rc = [%d]\n", __func__, rc);
                         goto out;
                 }
-                ecryptfs_lower_offset_for_extent(
-                        &offset, ((((loff_t)page->index)
-                                   * (PAGE_CACHE_SIZE
-                                      / crypt_stat->extent_size))
-                                  + extent_offset), crypt_stat);
-                rc = ecryptfs_write_lower(ecryptfs_inode, (enc_extent_virt +
-                                extent_offset * crypt_stat->extent_size),
-                                offset, crypt_stat->extent_size);
-                if (rc < 0) {
-                        ecryptfs_printk(KERN_ERR, "Error attempting "
-                                        "to write lower page; rc = [%d]"
-                                        "\n", rc);
-                        goto out;
-                }
+        }
+
+        ecryptfs_lower_offset_for_extent(&lower_offset,
+                page->index * (PAGE_CACHE_SIZE / crypt_stat->extent_size),
+                crypt_stat);
+        enc_extent_virt = kmap(enc_extent_page);
+        rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
+                                  PAGE_CACHE_SIZE);
+        kunmap(enc_extent_page);
+        if (rc < 0) {
+                ecryptfs_printk(KERN_ERR,
+                        "Error attempting to write lower page; rc = [%d]\n",
+                        rc);
+                goto out;
         }
         rc = 0;
 out:
         if (enc_extent_page) {
-                kunmap(enc_extent_page);
                 __free_page(enc_extent_page);
         }
         return rc;
@@ -599,6 +597,7 @@ int ecryptfs_decrypt_page(struct page *page)
         char *enc_extent_virt;
         struct page *enc_extent_page = NULL;
         unsigned long extent_offset;
+        loff_t lower_offset;
         int rc = 0;
 
         ecryptfs_inode = page->mapping->host;
@@ -612,26 +611,24 @@ int ecryptfs_decrypt_page(struct page *page)
                                 "encrypted extent\n");
                 goto out;
         }
+
+        ecryptfs_lower_offset_for_extent(&lower_offset,
+                page->index * (PAGE_CACHE_SIZE / crypt_stat->extent_size),
+                crypt_stat);
         enc_extent_virt = kmap(enc_extent_page);
+        rc = ecryptfs_read_lower(enc_extent_virt, lower_offset, PAGE_CACHE_SIZE,
+                                 ecryptfs_inode);
+        kunmap(enc_extent_page);
+        if (rc < 0) {
+                ecryptfs_printk(KERN_ERR,
+                        "Error attempting to read lower page; rc = [%d]\n",
+                        rc);
+                goto out;
+        }
+
         for (extent_offset = 0;
              extent_offset < (PAGE_CACHE_SIZE / crypt_stat->extent_size);
              extent_offset++) {
-                loff_t offset;
-
-                ecryptfs_lower_offset_for_extent(
-                        &offset, ((page->index * (PAGE_CACHE_SIZE
-                                                  / crypt_stat->extent_size))
-                                  + extent_offset), crypt_stat);
-                rc = ecryptfs_read_lower((enc_extent_virt +
-                                extent_offset * crypt_stat->extent_size),
-                                offset, crypt_stat->extent_size,
-                                ecryptfs_inode);
-                if (rc < 0) {
-                        ecryptfs_printk(KERN_ERR, "Error attempting "
-                                        "to read lower page; rc = [%d]"
-                                        "\n", rc);
-                        goto out;
-                }
                 rc = ecryptfs_decrypt_extent(page, crypt_stat, enc_extent_page,
                                              extent_offset);
                 if (rc) {
@@ -642,7 +639,6 @@ int ecryptfs_decrypt_page(struct page *page)
         }
 out:
         if (enc_extent_page) {
-                kunmap(enc_extent_page);
                 __free_page(enc_extent_page);
         }
         return rc;