From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f68.google.com ([209.85.214.68]:55126 "EHLO mail-it0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750735AbeBUAy5 (ORCPT ); Tue, 20 Feb 2018 19:54:57 -0500 Date: Tue, 20 Feb 2018 16:54:54 -0800 From: Eric Biggers To: Chandan Rajendra Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-fscrypt@vger.kernel.org, tytso@mit.edu Subject: Re: [RFC PATCH V2 10/11] Enable writing encrypted files in blocksize less than pagesize setup Message-ID: <20180221005454.GB252219@gmail.com> References: <20180212094347.22071-1-chandan@linux.vnet.ibm.com> <20180212094347.22071-11-chandan@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180212094347.22071-11-chandan@linux.vnet.ibm.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon, Feb 12, 2018 at 03:13:46PM +0530, Chandan Rajendra wrote: > This commit splits the functionality of fscrypt_encrypt_block(). The > allocation of fscrypt context and cipher text page is moved to a new > function fscrypt_prep_ciphertext_page(). > > ext4_bio_write_page() is modified to appropriately make use of the above > two functions. > > Signed-off-by: Chandan Rajendra Well, this patch also modifies ext4_bio_write_page() to support the blocksize < pagesize case. The commit message makes it sound like it's just refactoring. > diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c > index 0a4a1e7..1e869d5 100644 > --- a/fs/ext4/page-io.c > +++ b/fs/ext4/page-io.c > @@ -419,9 +419,12 @@ int ext4_bio_write_page(struct ext4_io_submit *io, > struct inode *inode = page->mapping->host; > unsigned block_start; > struct buffer_head *bh, *head; > + u64 blk_nr; > + gfp_t gfp_flags = GFP_NOFS; > int ret = 0; > int nr_submitted = 0; > int nr_to_submit = 0; > + int blocksize = (1 << inode->i_blkbits); > > BUG_ON(!PageLocked(page)); > BUG_ON(PageWriteback(page)); > @@ -475,15 +478,11 @@ int ext4_bio_write_page(struct ext4_io_submit *io, > nr_to_submit++; > } while ((bh = bh->b_this_page) != head); > > - bh = head = page_buffers(page); > - > - if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) && > - nr_to_submit) { > - gfp_t gfp_flags = GFP_NOFS; > - > - retry_encrypt: > - data_page = fscrypt_encrypt_block(inode, page, PAGE_SIZE, 0, > - page->index, gfp_flags); > + if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) > + && nr_to_submit) { > + retry_prep_ciphertext_page: > + data_page = fscrypt_prep_ciphertext_page(inode, page, > + gfp_flags); > if (IS_ERR(data_page)) { > ret = PTR_ERR(data_page); > if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) { > @@ -492,17 +491,28 @@ int ext4_bio_write_page(struct ext4_io_submit *io, > congestion_wait(BLK_RW_ASYNC, HZ/50); > } > gfp_flags |= __GFP_NOFAIL; > - goto retry_encrypt; > + goto retry_prep_ciphertext_page; > } > data_page = NULL; > goto out; > } > } > > + blk_nr = page->index << (PAGE_SHIFT - inode->i_blkbits); > + > /* Now submit buffers to write */ > + bh = head = page_buffers(page); > do { > if (!buffer_async_write(bh)) > continue; > + > + if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode)) { > + ret = fscrypt_encrypt_block(inode, page, data_page, blocksize, > + bh_offset(bh), blk_nr, gfp_flags); > + if (ret) > + break; > + } > + > ret = io_submit_add_bh(io, inode, > data_page ? data_page : page, bh); > if (ret) { > @@ -515,12 +525,12 @@ int ext4_bio_write_page(struct ext4_io_submit *io, > } > nr_submitted++; > clear_buffer_dirty(bh); > - } while ((bh = bh->b_this_page) != head); > + } while (++blk_nr, (bh = bh->b_this_page) != head); > > /* Error stopped previous loop? Clean up buffers... */ > if (ret) { > out: > - if (data_page) > + if (data_page && bh == head) > fscrypt_restore_control_page(data_page); > printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret); > redirty_page_for_writepage(wbc, page); I'm wondering why you didn't move the crypto stuff in ext4_bio_write_page() into a separate function like I had suggested? It's true we don't have to encrypt all the blocks in the page at once, but it would make the crypto stuff more self-contained. - Eric