From nobody Tue Feb 10 05:09:49 2026 Received: from mail-oa1-f51.google.com (mail-oa1-f51.google.com [209.85.160.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51D8A14D43D; Sat, 10 Aug 2024 08:28:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.160.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723278513; cv=none; b=dnVEOhs5U1nhM0uc7FAYTWBtjietuXKZBbMf0RyZHGUNxXpoOLFRnPvY3XiF6E/WXsuWUxMD6B6AnWsFjpPxJ75v9LIy7lmjjE2P/pY0oAL+2UCj0zwQ8RkesjWi253eKwBj2GotO2uSYL1ottgo3krK7alqfmWurBDD4fRtvFU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723278513; c=relaxed/simple; bh=RkuvIMkclvFPD0SfbQ0lukE1nGNH6KOgpTMJO2EH9vE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=oHN/RwqHaU38Dun6L4hGSAcJHeknUXUMj+Ljcr0hnNliCo/z+3DragMudNmLq+W0q5h6JSKeD5r30LrGvQ7TLT4kL7p154Y5eDWMFxU6Ez2zdd+Nq2X3W8p6OYY0/aG4fWEr9o5S8GuAtQzBaL/1ygJ9rAlUZRLMUGsqMR5JZto= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=OI7U16Jo; arc=none smtp.client-ip=209.85.160.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="OI7U16Jo" Received: by mail-oa1-f51.google.com with SMTP id 586e51a60fabf-2689e7a941fso1893398fac.3; Sat, 10 Aug 2024 01:28:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1723278510; x=1723883310; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=z1fH1Ho4GcX3EGjEBqcsALQduBlTVXsfPzay7ElzmRk=; b=OI7U16JoCcBYkfcNyHMjeIssxSWqXFnC10XgkBUPVul4UtSYvIrnwz9ecaKiR1czOv 28DgODmY/DNNxYM75XA58bNz7qYBiCDToZmrOjBiLCuCSlZmyqCI35QWpxfp0aB+pqc9 uFvdiqL2i82rnEw3zBA1mYF7OSyeetVqnm8un+GYdMv/6WVf2ku+wJErjPn6Heq6h2wr ZzfeYmg+JExmWvh1cXVfsouhaDXQz0ouZsVJOPnmnfDLsU2Otc7jP1w+RfgbCQXqcxaK 6tSsDjL73V8eQOpzgjFDuWYP2F47Q6/DqdqypenyMazgRY73QPQvz+6ywgAnH5pe3DIS yRrw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1723278510; x=1723883310; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=z1fH1Ho4GcX3EGjEBqcsALQduBlTVXsfPzay7ElzmRk=; b=bWb8nMIGex6RxqNPOcvB258+5IJOJ1OFSDyaLJkYx5WGd5O14B6YU1qbxBlIDvv0IE 118neJYOVZwEAJ3MI9tiRIrN5ssjGG8PLVleS2+drFtSeElsaBp2cOXSzR6x0qX8uzaW EkHwpbRWeQmNIsktdqPJ5pwW2ZOc9GgepJtmQt5WDvbZdVMhtGc1ko3IQhZTIO+Wkt27 6+kXBPG9YTabxfnxa1MYvNy7cHVYgxUEU1vxEKRoR7YGGhVmjmctBDx8OB7vP444KUzM rLxJyLMyaOfYdJhkXrqYkdXMeE0eeNY0jbHhDm2tp0LP90GiB85Y/zM8aaY378WH9DwN gyOw== X-Forwarded-Encrypted: i=1; AJvYcCUsVTq3J6RYtKPn3HMZEsZD6/7R6vMJapV9BrBfu7fg2Qf0xNi3PNN+U9V1FBK63YHvvFDwkE2WRu7h7uQnhJEsmhrD7ic+UJnj8St2 X-Gm-Message-State: AOJu0Yy3t4mmd/Ix0R2SbQh/KQxpDfaeF4ON4kldGMQHq6C8SkEOxVyH rxiD87eGJKo3sjHI8rL0zNB8QltuY5M+VEKKYLtyZlfs0Q9+EsUK X-Google-Smtp-Source: AGHT+IEzsxubHbJF6CWVozJ9oM3cep1yA8YrhjqmeIrMsateIHoyAtM/9NuUqRuSb+yVAM/rm5ksYA== X-Received: by 2002:a05:6870:3282:b0:261:1339:1cb9 with SMTP id 586e51a60fabf-26c62f21d48mr5160013fac.35.1723278510219; Sat, 10 Aug 2024 01:28:30 -0700 (PDT) Received: from localhost.localdomain ([163.53.18.10]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-710e5a8c454sm854092b3a.180.2024.08.10.01.28.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 10 Aug 2024 01:28:29 -0700 (PDT) From: zhangshida X-Google-Original-From: zhangshida To: tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.com Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, zhangshida@kylinos.cn, starzhangzsd@gmail.com, Baolin Liu , Jan Kara Subject: [PATCH v3 2/3] ext4: fix a potential assertion failure due to improperly dirtied buffer Date: Sat, 10 Aug 2024 16:28:13 +0800 Message-Id: <20240810082814.3709867-3-zhangshida@kylinos.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240810082814.3709867-1-zhangshida@kylinos.cn> References: <20240810082814.3709867-1-zhangshida@kylinos.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Shida Zhang On an old kernel version(4.19, ext3, data=3Djournal, pagesize=3D64k), an assertion failure will occasionally be triggered by the line below: ----------- jbd2_journal_commit_transaction { ... J_ASSERT_BH(bh, !buffer_dirty(bh)); /* * The buffer on BJ_Forget list and not jbddirty means ... } ----------- The same condition may also be applied to the lattest kernel version. When blocksize < pagesize and we truncate a file, there can be buffers in the mapping tail page beyond i_size. These buffers will be filed to transaction's BJ_Forget list by ext4_journalled_invalidatepage() during truncation. When the transaction doing truncate starts committing, we can grow the file again. This calls __block_write_begin() which allocates new blocks under these buffers in the tail page we go through the branch: if (buffer_new(bh)) { clean_bdev_bh_alias(bh); if (folio_test_uptodate(folio)) { clear_buffer_new(bh); set_buffer_uptodate(bh); mark_buffer_dirty(bh); continue; } ... } Hence buffers on BJ_Forget list of the committing transaction get marked dirty and this triggers the jbd2 assertion. Teach ext4_block_write_begin() to properly handle files with data journalling by avoiding dirtying them directly. Instead of folio_zero_new_buffers() we use ext4_journalled_zero_new_buffers() which takes care of handling journalling. We also don't need to mark new uptodate buffers as dirty in ext4_block_write_begin(). That will be either done either by block_commit_write() in case of success or by folio_zero_new_buffers() in case of failure. Reported-by: Baolin Liu Suggested-by: Jan Kara Signed-off-by: Shida Zhang --- fs/ext4/ext4.h | 3 ++- fs/ext4/inline.c | 7 ++++--- fs/ext4/inode.c | 30 ++++++++++++++++++++++-------- 3 files changed, 28 insertions(+), 12 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 5f8257b68190..b653bd423b11 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -3851,7 +3851,8 @@ static inline int ext4_buffer_uptodate(struct buffer_= head *bh) return buffer_uptodate(bh); } =20 -extern int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigne= d len, +extern int ext4_block_write_begin(handle_t *handle, struct folio *folio, + loff_t pos, unsigned len, get_block_t *get_block); #endif /* __KERNEL__ */ =20 diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index 0a1a8431e281..8d5599d5af27 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -601,10 +601,11 @@ static int ext4_convert_inline_data_to_extent(struct = address_space *mapping, goto out; =20 if (ext4_should_dioread_nolock(inode)) { - ret =3D ext4_block_write_begin(folio, from, to, + ret =3D ext4_block_write_begin(handle, folio, from, to, ext4_get_block_unwritten); } else - ret =3D ext4_block_write_begin(folio, from, to, ext4_get_block); + ret =3D ext4_block_write_begin(handle, folio, from, to, + ext4_get_block); =20 if (!ret && ext4_should_journal_data(inode)) { ret =3D ext4_walk_page_buffers(handle, inode, @@ -856,7 +857,7 @@ static int ext4_da_convert_inline_data_to_extent(struct= address_space *mapping, goto out; } =20 - ret =3D ext4_block_write_begin(folio, 0, inline_size, + ret =3D ext4_block_write_begin(NULL, folio, 0, inline_size, ext4_da_get_block_prep); if (ret) { up_read(&EXT4_I(inode)->xattr_sem); diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 6b15805ca88b..4c34827da56e 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -49,6 +49,11 @@ =20 #include =20 +static void ext4_journalled_zero_new_buffers(handle_t *handle, + struct inode *inode, + struct folio *folio, + unsigned from, unsigned to); + static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw, struct ext4_inode_info *ei) { @@ -1041,7 +1046,8 @@ int do_journal_get_write_access(handle_t *handle, str= uct inode *inode, return ret; } =20 -int ext4_block_write_begin(struct folio *folio, loff_t pos, unsigned len, +int ext4_block_write_begin(handle_t *handle, struct folio *folio, + loff_t pos, unsigned len, get_block_t *get_block) { unsigned from =3D pos & (PAGE_SIZE - 1); @@ -1055,6 +1061,7 @@ int ext4_block_write_begin(struct folio *folio, loff_= t pos, unsigned len, struct buffer_head *bh, *head, *wait[2]; int nr_wait =3D 0; int i; + bool should_journal_data =3D ext4_should_journal_data(inode); =20 BUG_ON(!folio_test_locked(folio)); BUG_ON(from > PAGE_SIZE); @@ -1083,11 +1090,11 @@ int ext4_block_write_begin(struct folio *folio, lof= f_t pos, unsigned len, err =3D get_block(inode, block, bh, 1); if (err) break; + if (should_journal_data) + do_journal_get_write_access(handle, inode, bh); if (buffer_new(bh)) { if (folio_test_uptodate(folio)) { - clear_buffer_new(bh); set_buffer_uptodate(bh); - mark_buffer_dirty(bh); continue; } if (block_end > to || block_start < from) @@ -1117,7 +1124,11 @@ int ext4_block_write_begin(struct folio *folio, loff= _t pos, unsigned len, err =3D -EIO; } if (unlikely(err)) { - folio_zero_new_buffers(folio, from, to); + if (should_journal_data) + ext4_journalled_zero_new_buffers(handle, inode, folio, + from, to); + else + folio_zero_new_buffers(folio, from, to); } #ifdef CONFIG_FS_ENCRYPTION else if (fscrypt_inode_uses_fs_layer_crypto(inode)) { @@ -1218,10 +1229,11 @@ static int ext4_write_begin(struct file *file, stru= ct address_space *mapping, folio_wait_stable(folio); =20 if (ext4_should_dioread_nolock(inode)) - ret =3D ext4_block_write_begin(folio, pos, len, + ret =3D ext4_block_write_begin(handle, folio, pos, len, ext4_get_block_unwritten); else - ret =3D ext4_block_write_begin(folio, pos, len, ext4_get_block); + ret =3D ext4_block_write_begin(handle, folio, pos, len, + ext4_get_block); if (!ret && ext4_should_journal_data(inode)) { ret =3D ext4_walk_page_buffers(handle, inode, folio_buffers(folio), from, to, @@ -2954,7 +2966,8 @@ static int ext4_da_write_begin(struct file *file, str= uct address_space *mapping, if (IS_ERR(folio)) return PTR_ERR(folio); =20 - ret =3D ext4_block_write_begin(folio, pos, len, ext4_da_get_block_prep); + ret =3D ext4_block_write_begin(NULL, folio, pos, len, + ext4_da_get_block_prep); if (ret < 0) { folio_unlock(folio); folio_put(folio); @@ -6208,7 +6221,8 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) if (folio_pos(folio) + len > size) len =3D size - folio_pos(folio); =20 - err =3D __block_write_begin(&folio->page, 0, len, ext4_get_block); + err =3D ext4_block_write_begin(handle, folio, 0, len, + ext4_get_block); if (!err) { ret =3D VM_FAULT_SIGBUS; if (ext4_journal_folio_buffers(handle, folio, len)) --=20 2.33.0