-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;
-}
-