ecryptfs: remove unnecessary decrypt when extending a file
Removes an unecessary page decrypt from ecryptfs_begin_write when the
page is beyond the current file size. Previously, the call to
ecryptfs_decrypt_page would result in a read of 0 bytes, but still
attempt to decrypt an entire page. This patch detects that case and
merely zeros the page before marking it up-to-date.
Signed-off-by: Frank Swiderski <fes@chromium.org>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
index 4b90113..cc64fca 100644
--- a/fs/ecryptfs/mmap.c
+++ b/fs/ecryptfs/mmap.c
@@ -290,6 +290,7 @@
return -ENOMEM;
*pagep = page;
+ prev_page_end_size = ((loff_t)index << PAGE_CACHE_SHIFT);
if (!PageUptodate(page)) {
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(mapping->host)->crypt_stat;
@@ -335,18 +336,23 @@
SetPageUptodate(page);
}
} else {
- rc = ecryptfs_decrypt_page(page);
- if (rc) {
- printk(KERN_ERR "%s: Error decrypting page "
- "at index [%ld]; rc = [%d]\n",
- __func__, page->index, rc);
- ClearPageUptodate(page);
- goto out;
+ if (prev_page_end_size
+ >= i_size_read(page->mapping->host)) {
+ zero_user(page, 0, PAGE_CACHE_SIZE);
+ } else {
+ rc = ecryptfs_decrypt_page(page);
+ if (rc) {
+ printk(KERN_ERR "%s: Error decrypting "
+ "page at index [%ld]; "
+ "rc = [%d]\n",
+ __func__, page->index, rc);
+ ClearPageUptodate(page);
+ goto out;
+ }
}
SetPageUptodate(page);
}
}
- prev_page_end_size = ((loff_t)index << PAGE_CACHE_SHIFT);
/* If creating a page or more of holes, zero them out via truncate.
* Note, this will increase i_size. */
if (index != 0) {
