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Commit 24562486 authored by Frank Swiderski's avatar Frank Swiderski Committed by Tyler Hicks
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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: default avatarFrank Swiderski <fes@chromium.org>
Signed-off-by: default avatarTyler Hicks <tyhicks@linux.vnet.ibm.com>
parent f24b3887

fs/ecryptfs/mmap.c

+14 −8
Original line number Diff line number Diff line
@@ -290,6 +290,7 @@ static int ecryptfs_write_begin(struct file *file, 
		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;
@@ -334,19 +335,24 @@ static int ecryptfs_write_begin(struct file *file, 
				}

				SetPageUptodate(page);

			}

		} else {

			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",

					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) {