From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 325A0C43381 for ; Thu, 28 Mar 2019 15:48:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ED0F720811 for ; Thu, 28 Mar 2019 15:48:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="175UWisI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726302AbfC1PsX (ORCPT ); Thu, 28 Mar 2019 11:48:23 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:49578 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725816AbfC1PsX (ORCPT ); Thu, 28 Mar 2019 11:48:23 -0400 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x2SFhjr7134766; Thu, 28 Mar 2019 15:48:18 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=sc/fLePp7sLYvfLqBxBE8Jb+ZMN4qbX8t5nNr1GxHl8=; b=175UWisItXxP6ajK5SutkO7cY3DqgQ2Kec4jJhy1kFTiQJ3YP5lmbb2jENAiRglpq1wF gEVFFxHfzVQbkxSW+k25HCTZ7oKzI5jltokY7I4Nzf58AIQ5QBPpJQP4takqOhoGwt2j hoizl5xRNdKKWC23m/9V973E2qsVeyYlK8hAQ4gOywJtOx5q1iPPrGD95b8SrIf9XSGM XSHZw5blhigS9zeJ64rBSg4Y/H4apgbaH78a6HYrQgpyCFaA7duq6GpUiTJJM2Qq9BKp DxsslMq/ML+Gtgmc/skxwb2jUimSKHi1x6za/KFA7rderikfdvS3tXi6biQkKKgLlvW7 Pg== Received: from userv0021.oracle.com (userv0021.oracle.com [156.151.31.71]) by userp2120.oracle.com with ESMTP id 2re6djqj2a-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 15:48:18 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0021.oracle.com (8.14.4/8.14.4) with ESMTP id x2SFmHHv024531 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Mar 2019 15:48:17 GMT Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x2SFmHBc003667; Thu, 28 Mar 2019 15:48:17 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 28 Mar 2019 08:48:17 -0700 Date: Thu, 28 Mar 2019 08:48:16 -0700 From: "Darrick J. Wong" To: Goldwyn Rodrigues Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Goldwyn Rodrigues Subject: Re: [PATCH 15/15] btrfs: Writeprotect mmap pages on snapshot Message-ID: <20190328154816.GG1172@magnolia> References: <20190326190301.32365-1-rgoldwyn@suse.de> <20190326190301.32365-16-rgoldwyn@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190326190301.32365-16-rgoldwyn@suse.de> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9209 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1903280106 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Mar 26, 2019 at 02:03:01PM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues > > Inorder to make sure mmap'd files don't change after snapshot, > writeprotect the mmap pages on snapshot. This is done by performing > a data writeback on the pages (which simply mark the pages are > wrprotected). This way if the user process tries to access the memory > we will get another fault and we can perform a CoW. > > In order to accomplish this, we tag all CoW pages as > PAGECACHE_TAG_TOWRITE, and add the mmapd inode in delalloc_inodes. > During snapshot, it starts writeback of all delalloc'd inodes and > here we perform a data writeback. We don't want to keep the inodes > in delalloc_inodes until it umount (WARN_ON), so we remove it > during inode evictions. > > This looks hackish. Other alternatives could be to create another > list for mmap'd files or rename delalloc_inodes to writeback_inodes. > Suggestions? Is there a function to invalidate only the writable mappings in the pagecache? Could there be? > Signed-off-by: Goldwyn Rodrigues > --- > fs/btrfs/ctree.h | 3 ++- > fs/btrfs/dax.c | 7 +++++++ > fs/btrfs/inode.c | 13 ++++++++++++- > fs/dax.c | 3 +++ > 4 files changed, 24 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h > index 21068dc4a95a..68a63d93556a 100644 > --- a/fs/btrfs/ctree.h > +++ b/fs/btrfs/ctree.h > @@ -3252,7 +3252,8 @@ int btrfs_create_subvol_root(struct btrfs_trans_handle *trans, > struct btrfs_root *new_root, > struct btrfs_root *parent_root, > u64 new_dirid); > - void btrfs_set_delalloc_extent(struct inode *inode, struct extent_state *state, > +void btrfs_add_delalloc_inodes(struct btrfs_root *root, struct inode *inode); > +void btrfs_set_delalloc_extent(struct inode *inode, struct extent_state *state, > unsigned *bits); > void btrfs_clear_delalloc_extent(struct inode *inode, > struct extent_state *state, unsigned *bits); > diff --git a/fs/btrfs/dax.c b/fs/btrfs/dax.c > index d73945d50b88..bcb961242c74 100644 > --- a/fs/btrfs/dax.c > +++ b/fs/btrfs/dax.c > @@ -166,10 +166,17 @@ vm_fault_t btrfs_dax_fault(struct vm_fault *vmf) > { > vm_fault_t ret; > pfn_t pfn; > + struct inode *inode = file_inode(vmf->vma->vm_file); > + struct btrfs_inode *binode = BTRFS_I(inode); > ret = dax_iomap_fault(vmf, PE_SIZE_PTE, &pfn, NULL, &btrfs_iomap_ops); > if (ret & VM_FAULT_NEEDDSYNC) > ret = dax_finish_sync_fault(vmf, PE_SIZE_PTE, pfn); > > + /* Insert into delalloc so we get writeback calls on snapshots */ > + if (vmf->flags & FAULT_FLAG_WRITE && > + !test_bit(BTRFS_INODE_IN_DELALLOC_LIST, &binode->runtime_flags)) > + btrfs_add_delalloc_inodes(binode->root, inode); > + > return ret; > } > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index 5350e5f23728..3b72c1c96b34 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -1713,7 +1713,7 @@ void btrfs_merge_delalloc_extent(struct inode *inode, struct extent_state *new, > spin_unlock(&BTRFS_I(inode)->lock); > } > > -static void btrfs_add_delalloc_inodes(struct btrfs_root *root, > +void btrfs_add_delalloc_inodes(struct btrfs_root *root, > struct inode *inode) > { > struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > @@ -5358,12 +5358,17 @@ void btrfs_evict_inode(struct inode *inode) > { > struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > struct btrfs_trans_handle *trans; > + struct btrfs_inode *binode = BTRFS_I(inode); > struct btrfs_root *root = BTRFS_I(inode)->root; > struct btrfs_block_rsv *rsv; > int ret; > > trace_btrfs_inode_evict(inode); > > + if (IS_DAX(inode) > + && test_bit(BTRFS_INODE_IN_DELALLOC_LIST, &binode->runtime_flags)) > + btrfs_del_delalloc_inode(root, binode); > + > if (!root) { > clear_inode(inode); > return; > @@ -8683,6 +8688,10 @@ static int btrfs_dax_writepages(struct address_space *mapping, > { > struct inode *inode = mapping->host; > struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); > + struct btrfs_inode *binode = BTRFS_I(inode); > + if ((wbc->sync_mode == WB_SYNC_ALL) && > + test_bit(BTRFS_INODE_IN_DELALLOC_LIST, &binode->runtime_flags)) > + btrfs_del_delalloc_inode(binode->root, binode); > return dax_writeback_mapping_range(mapping, fs_info->fs_devices->latest_bdev, > wbc); > } > @@ -9981,6 +9990,8 @@ static void btrfs_run_delalloc_work(struct btrfs_work *work) > delalloc_work = container_of(work, struct btrfs_delalloc_work, > work); > inode = delalloc_work->inode; > + if (IS_DAX(inode)) > + filemap_fdatawrite(inode->i_mapping); > filemap_flush(inode->i_mapping); > if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, > &BTRFS_I(inode)->runtime_flags)) > diff --git a/fs/dax.c b/fs/dax.c > index 93146142bb00..c42e9cb486ef 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -753,6 +753,9 @@ static void *dax_insert_entry(struct xa_state *xas, > if (dirty) > xas_set_mark(xas, PAGECACHE_TAG_DIRTY); > > + if (cow) > + xas_set_mark(xas, PAGECACHE_TAG_TOWRITE); > + Was this supposed to go with the dax_insert_entry changes (patch 9)? --D > xas_unlock_irq(xas); > return entry; > } > -- > 2.16.4 >