From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Wang Subject: [PATCH] eCryptfs: Avoid unnecessary disk read and data decryption during writing Date: Tue, 30 Oct 2012 19:52:40 +0800 Message-ID: <1351597960-1503-1-git-send-email-wangli@kylinos.com.cn> Return-path: Received: from [118.186.34.234] ([118.186.34.234]:55337 "EHLO kylinos.com.cn" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750880Ab2J3EF7 (ORCPT ); Tue, 30 Oct 2012 00:05:59 -0400 Sender: ecryptfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Tyler Hicks , Dustin Kirkland Cc: ecryptfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Li Wang , Yunchuan Wen ecryptfs_write_begin grabs a page from page cache for writing. If the page contains invalid data, or data older than the counterpart on the disk, eCryptfs will read out the corresponing data from the disk into the page, decrypt them, then perform writing. However, for this page, if the length of the data to be written into is equal to page size, that means the whole page of data will be overwritten, in which case, it does not matter whatever the data were before, it is beneficial to perform writing directly rather than bothering to read and decrypt first. With this optimization, according to our test on a machine with Intel Core 2 Duo processor, iozone 'write' operation on an existing file with write size being multiple of page size will enjoy a steady 3x speedup. Signed-off-by: Li Wang Signed-off-by: Yunchuan Wen Reviewed-by: Tyler Hicks --- fs/ecryptfs/mmap.c | 12 ++++++++++-- 1 files changed, 10 insertions(+), 2 deletions(-) diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c index bd1d57f..564a1fa 100644 --- a/fs/ecryptfs/mmap.c +++ b/fs/ecryptfs/mmap.c @@ -338,7 +338,8 @@ static int ecryptfs_write_begin(struct file *file, if (prev_page_end_size >= i_size_read(page->mapping->host)) { zero_user(page, 0, PAGE_CACHE_SIZE); - } else { + SetPageUptodate(page); + } else if (len < PAGE_CACHE_SIZE) { rc = ecryptfs_decrypt_page(page); if (rc) { printk(KERN_ERR "%s: Error decrypting " @@ -348,8 +349,8 @@ static int ecryptfs_write_begin(struct file *file, ClearPageUptodate(page); goto out; } + SetPageUptodate(page); } - SetPageUptodate(page); } } /* If creating a page or more of holes, zero them out via truncate. @@ -499,6 +500,13 @@ static int ecryptfs_write_end(struct file *file, } goto out; } + if (!PageUptodate(page)) { + if (copied < PAGE_CACHE_SIZE) { + rc = 0; + goto out; + } + SetPageUptodate(page); + } /* Fills in zeros if 'to' goes beyond inode size */ rc = fill_zeros_to_end_of_page(page, to); if (rc) { -- 1.7.6.5