eCryptfs: Simplify lower file offset calculation
Now that lower filesystem IO operations occur for complete
PAGE_CACHE_SIZE bytes, the calculation for converting an eCryptfs extent
index into a lower file offset can be simplified.
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 4185584..3547708 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -407,15 +407,15 @@
}
/**
- * ecryptfs_lower_offset_for_extent
+ * lower_offset_for_page
*
* Convert an eCryptfs page index into a lower byte offset
*/
-static void ecryptfs_lower_offset_for_extent(loff_t *offset, loff_t extent_num,
- struct ecryptfs_crypt_stat *crypt_stat)
+static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
+ struct page *page)
{
- (*offset) = ecryptfs_lower_header_size(crypt_stat)
- + (crypt_stat->extent_size * extent_num);
+ return ecryptfs_lower_header_size(crypt_stat) +
+ (page->index << PAGE_CACHE_SHIFT);
}
/**
@@ -517,9 +517,7 @@
}
}
- ecryptfs_lower_offset_for_extent(&lower_offset,
- page->index * (PAGE_CACHE_SIZE / crypt_stat->extent_size),
- crypt_stat);
+ lower_offset = lower_offset_for_page(crypt_stat, page);
enc_extent_virt = kmap(enc_extent_page);
rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
PAGE_CACHE_SIZE);
@@ -612,9 +610,7 @@
goto out;
}
- ecryptfs_lower_offset_for_extent(&lower_offset,
- page->index * (PAGE_CACHE_SIZE / crypt_stat->extent_size),
- crypt_stat);
+ lower_offset = lower_offset_for_page(crypt_stat, page);
enc_extent_virt = kmap(enc_extent_page);
rc = ecryptfs_read_lower(enc_extent_virt, lower_offset, PAGE_CACHE_SIZE,
ecryptfs_inode);