From patchwork Mon Apr 29 17:26:47 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Goldwyn Rodrigues X-Patchwork-Id: 10922293 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 333F614B6 for ; Mon, 29 Apr 2019 17:27:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1A66B2883B for ; Mon, 29 Apr 2019 17:27:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0F0D72884A; Mon, 29 Apr 2019 17:27:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9FFE42883B for ; Mon, 29 Apr 2019 17:27:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729018AbfD2R1n (ORCPT ); Mon, 29 Apr 2019 13:27:43 -0400 Received: from mx2.suse.de ([195.135.220.15]:58398 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728997AbfD2R1k (ORCPT ); Mon, 29 Apr 2019 13:27:40 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id B6119AE8B; Mon, 29 Apr 2019 17:27:38 +0000 (UTC) From: Goldwyn Rodrigues To: linux-btrfs@vger.kernel.org Cc: kilobyte@angband.pl, linux-fsdevel@vger.kernel.org, jack@suse.cz, david@fromorbit.com, willy@infradead.org, hch@lst.de, darrick.wong@oracle.com, dsterba@suse.cz, nborisov@suse.com, linux-nvdimm@lists.01.org, Goldwyn Rodrigues Subject: [PATCH 16/18] btrfs: Writeprotect mmap pages on snapshot Date: Mon, 29 Apr 2019 12:26:47 -0500 Message-Id: <20190429172649.8288-17-rgoldwyn@suse.de> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190429172649.8288-1-rgoldwyn@suse.de> References: <20190429172649.8288-1-rgoldwyn@suse.de> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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. Signed-off-by: Goldwyn Rodrigues --- fs/btrfs/ctree.h | 3 ++- fs/btrfs/dax.c | 7 +++++++ fs/btrfs/inode.c | 13 ++++++++++++- 3 files changed, 21 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index ee1ed18f8b3c..d1b70f24adeb 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 bf2ddac5b5a1..20ec2ec49c68 100644 --- a/fs/btrfs/dax.c +++ b/fs/btrfs/dax.c @@ -222,10 +222,17 @@ 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 7e88280a2c3b..e98fb512e1ca 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))