From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Biggers Subject: [PATCH 11/13] ext4: decrypt only the needed blocks in ext4_block_write_begin() Date: Wed, 1 May 2019 15:45:13 -0700 Message-ID: <20190501224515.43059-12-ebiggers@kernel.org> References: <20190501224515.43059-1-ebiggers@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-4.v29.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from ) id 1hLxzX-0006s1-GN for linux-f2fs-devel@lists.sourceforge.net; Wed, 01 May 2019 22:46:19 +0000 Received: from mail.kernel.org ([198.145.29.99]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) id 1hLxzW-004Tjo-8S for linux-f2fs-devel@lists.sourceforge.net; Wed, 01 May 2019 22:46:19 +0000 In-Reply-To: <20190501224515.43059-1-ebiggers@kernel.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-mtd@lists.infradead.org, Chandan Rajendra , linux-f2fs-devel@lists.sourceforge.net From: Chandan Rajendra In ext4_block_write_begin(), only decrypt the blocks that actually need to be decrypted (up to two blocks which intersect the boundaries of the region that will be written to), rather than assuming blocksize == PAGE_SIZE and decrypting the whole page. This is in preparation for allowing encryption on ext4 filesystems with blocksize != PAGE_SIZE. Signed-off-by: Chandan Rajendra (EB: rebase onto previous changes and improve the commit message) Signed-off-by: Eric Biggers --- fs/ext4/inode.c | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 9382e1bcefe49..d24c50e4598f0 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -1160,8 +1160,10 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len, int err = 0; unsigned blocksize = inode->i_sb->s_blocksize; unsigned bbits; - struct buffer_head *bh, *head, *wait[2], **wait_bh = wait; + struct buffer_head *bh, *head, *wait[2]; + int nr_wait = 0; bool decrypt = false; + int i; BUG_ON(!PageLocked(page)); BUG_ON(from > PAGE_SIZE); @@ -1213,24 +1215,31 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len, !buffer_unwritten(bh) && (block_start < from || block_end > to)) { ll_rw_block(REQ_OP_READ, 0, 1, &bh); - *wait_bh++ = bh; + wait[nr_wait++] = bh; decrypt = IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode); } } /* * If we issued read requests, let them complete. */ - while (wait_bh > wait) { - wait_on_buffer(*--wait_bh); - if (!buffer_uptodate(*wait_bh)) + for (i = 0; i < nr_wait; i++) { + wait_on_buffer(wait[i]); + if (!buffer_uptodate(wait[i])) err = -EIO; } if (unlikely(err)) { page_zero_new_buffers(page, from, to); } else if (decrypt) { - err = fscrypt_decrypt_pagecache_blocks(page, PAGE_SIZE, 0); - if (err) - clear_buffer_uptodate(*wait_bh); + for (i = 0; i < nr_wait; i++) { + int err2; + + err2 = fscrypt_decrypt_pagecache_blocks(page, blocksize, + bh_offset(wait[i])); + if (err2) { + clear_buffer_uptodate(wait[i]); + err = err2; + } + } } return err; -- 2.21.0.593.g511ec345e18-goog