From patchwork Fri Feb 24 02:06:46 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qu Wenruo X-Patchwork-Id: 9589253 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 7B4FC6042D for ; Fri, 24 Feb 2017 02:08:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6A1AB28765 for ; Fri, 24 Feb 2017 02:08:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5E90028799; Fri, 24 Feb 2017 02:08:10 +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=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham 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 7D55628765 for ; Fri, 24 Feb 2017 02:08:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751283AbdBXCHX (ORCPT ); Thu, 23 Feb 2017 21:07:23 -0500 Received: from cn.fujitsu.com ([59.151.112.132]:24324 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751259AbdBXCHW (ORCPT ); Thu, 23 Feb 2017 21:07:22 -0500 X-IronPort-AV: E=Sophos;i="5.22,518,1449504000"; d="scan'208";a="15907945" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 24 Feb 2017 10:06:54 +0800 Received: from G08CNEXCHPEKD01.g08.fujitsu.local (unknown [10.167.33.80]) by cn.fujitsu.com (Postfix) with ESMTP id CFC9D47D8AA5; Fri, 24 Feb 2017 10:06:52 +0800 (CST) Received: from localhost.localdomain (10.167.226.34) by G08CNEXCHPEKD01.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.319.2; Fri, 24 Feb 2017 10:06:51 +0800 From: Qu Wenruo To: , , Subject: [PATCH v4] btrfs: Handle delalloc error correctly to avoid ordered extent deadlock Date: Fri, 24 Feb 2017 10:06:46 +0800 Message-ID: <20170224020646.12668-1-quwenruo@cn.fujitsu.com> X-Mailer: git-send-email 2.11.1 MIME-Version: 1.0 X-Originating-IP: [10.167.226.34] X-yoursite-MailScanner-ID: CFC9D47D8AA5.A3479 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: quwenruo@cn.fujitsu.com 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 If run btrfs/125 with nospace_cache or space_cache=v2 mount option, btrfs will block with the following backtrace: Call Trace: __schedule+0x2d4/0xae0 schedule+0x3d/0x90 btrfs_start_ordered_extent+0x160/0x200 [btrfs] ? wake_atomic_t_function+0x60/0x60 btrfs_run_ordered_extent_work+0x25/0x40 [btrfs] btrfs_scrubparity_helper+0x1c1/0x620 [btrfs] btrfs_flush_delalloc_helper+0xe/0x10 [btrfs] process_one_work+0x2af/0x720 ? process_one_work+0x22b/0x720 worker_thread+0x4b/0x4f0 kthread+0x10f/0x150 ? process_one_work+0x720/0x720 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x2e/0x40 The direct cause is the error handler in run_delalloc_nocow() doesn't handle error from btrfs_reloc_clone_csums() well. The error handler of run_delalloc_nocow() will clear dirty and finish IO for the pages in that extent. However we have already inserted one ordered extent. And that ordered extent is relying on endio hooks to wait all its pages to finish, while only the first page will finish. This makes that ordered extent never finish, so blocking the file system. Although the root cause is still in RAID5/6, it won't hurt to fix the error routine first. This patch will slightly modify one existing function, btrfs_endio_direct_write_update_ordered() to handle free space inode, and skip releasing metadata, which will be handled by extent_clear_unlock_delalloc(). And use it as base to implement one inline function, btrfs_cleanup_ordered_extents() to handle the error in run_delalloc_nocow() and cow_file_range(). Also, extent_clear_unlock_delalloc() will handle all the metadata release, so btrfs_cleanup_ordered_extents() doesn't need to do it. For compression, it's calling writepage_end_io_hook() itself to handle its error, and any submitted ordered extent will have its bio submitted, so no need to worry about compression part. Suggested-by: Filipe Manana Signed-off-by: Qu Wenruo --- v2: Add BTRFS_ORDERED_SKIP_METADATA flag to avoid double reducing outstanding extents, which is already done by extent_clear_unlock_delalloc() with EXTENT_DO_ACCOUNT control bit v3: Skip first page to avoid underflow ordered->bytes_left. Fix range passed in cow_file_range() which doesn't cover the whole extent. Expend extent_clear_unlock_delalloc() range to allow them to handle metadata release. v4: Don't use extra bit to skip metadata freeing for ordered extent, but only handle btrfs_reloc_clone_csums() error just before processing next extent. This makes error handle much easier for run_delalloc_nocow(). --- fs/btrfs/extent_io.c | 1 - fs/btrfs/inode.c | 112 +++++++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 96 insertions(+), 17 deletions(-) diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 4ac383a3a649..a14d1b0840c5 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3258,7 +3258,6 @@ static noinline_for_stack int writepage_delalloc(struct inode *inode, delalloc_end, &page_started, nr_written); - /* File system has been set read-only */ if (ret) { SetPageError(page); /* fill_delalloc should be return < 0 for error diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 1e861a063721..b98a92807aa2 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -116,6 +116,34 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start, static int btrfs_dirty_inode(struct inode *inode); + +static void __endio_write_update_ordered(struct inode *inode, + const u64 offset, const u64 bytes, + bool uptodate, bool cleanup); +static inline void btrfs_endio_direct_write_update_ordered(struct inode *inode, + const u64 offset, + const u64 bytes, + const int uptodate) +{ + return __endio_write_update_ordered(inode, offset, bytes, uptodate, false); +} + +/* + * Cleanup all submitted ordered extent in specified range to handle error + * in cow_file_range() and run_delalloc_nocow(). + * Compression handles error and ordered extent submission all by themselves, + * so no need to call this function. + * + * NOTE: caller must ensure extent_clear_unlock_delalloc() in error handler + * doesn't cover any range of submitted ordered extent. + * Or we will double free metadata for submitted ordered extent. + */ +static inline void btrfs_cleanup_ordered_extents(struct inode *inode, + u64 offset, u64 bytes) +{ + return __endio_write_update_ordered(inode, offset, bytes, false, true); +} + #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS void btrfs_test_inode_set_ops(struct inode *inode) { @@ -950,6 +978,7 @@ static noinline int cow_file_range(struct inode *inode, u64 disk_num_bytes; u64 cur_alloc_size; u64 blocksize = fs_info->sectorsize; + u64 orig_start = start; struct btrfs_key ins; struct extent_map *em; struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree; @@ -1052,15 +1081,22 @@ static noinline int cow_file_range(struct inode *inode, BTRFS_DATA_RELOC_TREE_OBJECTID) { ret = btrfs_reloc_clone_csums(inode, start, cur_alloc_size); + /* + * Only drop cache here, and process as normal. + * + * We must not allow extent_clear_unlock_delalloc() + * to free meta of this ordered extent, as its + * meta should be freed by btrfs_finish_ordered_io(). + * + * So we must continue until processing next extent + */ if (ret) - goto out_drop_extent_cache; + btrfs_drop_extent_cache(inode, start, + start + ram_size - 1, 0); } btrfs_dec_block_group_reservations(fs_info, ins.objectid); - if (disk_num_bytes < cur_alloc_size) - break; - /* we're not doing compressed IO, don't unlock the first * page (which the caller expects to stay locked), don't * clear any dirty bits and don't set any writeback bits @@ -1076,10 +1112,21 @@ static noinline int cow_file_range(struct inode *inode, delalloc_end, locked_page, EXTENT_LOCKED | EXTENT_DELALLOC, op); - disk_num_bytes -= cur_alloc_size; + if (disk_num_bytes < cur_alloc_size) + disk_num_bytes = 0; + else + disk_num_bytes -= cur_alloc_size; num_bytes -= cur_alloc_size; alloc_hint = ins.objectid + ins.offset; start += cur_alloc_size; + + /* + * btrfs_reloc_clone_csums() error, now + * extent_clear_unlock_delalloc() in out_unlock() won't + * double free metadata of current oredered extent. + */ + if (ret) + goto out_reserve; } out: return ret; @@ -1096,6 +1143,7 @@ static noinline int cow_file_range(struct inode *inode, EXTENT_DELALLOC | EXTENT_DEFRAG, PAGE_UNLOCK | PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK); + btrfs_cleanup_ordered_extents(inode, orig_start, end - orig_start + 1); goto out; } @@ -1496,15 +1544,14 @@ static noinline int run_delalloc_nocow(struct inode *inode, BUG_ON(ret); /* -ENOMEM */ if (root->root_key.objectid == - BTRFS_DATA_RELOC_TREE_OBJECTID) { + BTRFS_DATA_RELOC_TREE_OBJECTID) + /* + * Error handled later, as we must prevent + * extent_clear_unlock_delalloc() in error handler + * from freeing metadata of submitted ordered extent. + */ ret = btrfs_reloc_clone_csums(inode, cur_offset, num_bytes); - if (ret) { - if (!nolock && nocow) - btrfs_end_write_no_snapshoting(root); - goto error; - } - } extent_clear_unlock_delalloc(inode, cur_offset, cur_offset + num_bytes - 1, end, @@ -1516,6 +1563,14 @@ static noinline int run_delalloc_nocow(struct inode *inode, if (!nolock && nocow) btrfs_end_write_no_snapshoting(root); cur_offset = extent_end; + + /* + * btrfs_reloc_clone_csums() error, now we're OK to call error + * handler, as metadata for submitted ordered extent will only + * be freed by btrfs_finish_ordered_io(). + */ + if (ret) + goto error; if (cur_offset > end) break; } @@ -1546,6 +1601,12 @@ static noinline int run_delalloc_nocow(struct inode *inode, PAGE_CLEAR_DIRTY | PAGE_SET_WRITEBACK | PAGE_END_WRITEBACK); + /* + * It's possible that last ordered extent covered the last part + * but failed. In that case we still need to clean them up. + */ + if (ret) + btrfs_cleanup_ordered_extents(inode, start, end - start + 1); btrfs_free_path(path); return ret; } @@ -8185,17 +8246,36 @@ static void btrfs_endio_direct_read(struct bio *bio) bio_put(bio); } -static void btrfs_endio_direct_write_update_ordered(struct inode *inode, - const u64 offset, - const u64 bytes, - const int uptodate) +static void __endio_write_update_ordered(struct inode *inode, + const u64 offset, const u64 bytes, + bool uptodate, bool cleanup) { struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); struct btrfs_ordered_extent *ordered = NULL; + struct btrfs_workqueue *wq; + btrfs_work_func_t func; u64 ordered_offset = offset; u64 ordered_bytes = bytes; int ret; + if (btrfs_is_free_space_inode(inode)) { + wq = fs_info->endio_freespace_worker; + func = btrfs_freespace_write_helper; + } else { + wq = fs_info->endio_write_workers; + func = btrfs_endio_write_helper; + } + + /* + * In cleanup case, the first page of the range will be handled + * by end_extent_writepage() under done tag of __extent_writepage(). + * + * So we must skip first page, or we will underflow ordered->bytes_left + */ + if (cleanup) { + ordered_offset += PAGE_SIZE; + ordered_bytes -= PAGE_SIZE; + } again: ret = btrfs_dec_test_first_ordered_pending(inode, &ordered, &ordered_offset,