From nobody Mon Feb 9 18:43:24 2026 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 88EDA37F8D3; Tue, 3 Feb 2026 06:30:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770100225; cv=none; b=WggmjBXwwaZfCFFCGZRYONf5pCzAJl20mwEWYL8mvRyi+yMVE1yB+O97JxCwHq0Jj4CfDE2gDJvWqpDqmNav+OfE7AgrKaRGtgqIcLW2VrvFKrtzTXr/b/N9frPqlvqhv3oYEBxk46mds9wZ36owRtVQpK+jlr9FQQqmmw+uoVg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770100225; c=relaxed/simple; bh=BrGxNbkrwS6XZ9Qc2+PxxE0UTblauY+mqetFSTrayl8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XLDSORApIuNODXA4ylrqLR/yjb5red7oXDnO+hvsTdvwZuCYRBLzoyaCUcdK+N+vwmqn9nRIknKGqW7Ab3u/tjnfZK6vx+oTQUCtUXeh1wZpY6cw/2es29kL502EP0szlhpiQDpuqXMBOJQR+ZmEjGsINdVsFiXSN1f0DU1pY8E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.177]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4f4trK3yqBzKHMc6; Tue, 3 Feb 2026 14:29:53 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id D720B4058C; Tue, 3 Feb 2026 14:30:14 +0800 (CST) Received: from huaweicloud.com (unknown [10.50.85.155]) by APP4 (Coremail) with SMTP id gCh0CgAHaPjnlYFpiadbGA--.27803S18; Tue, 03 Feb 2026 14:30:14 +0800 (CST) From: Zhang Yi To: linux-ext4@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, ojaswin@linux.ibm.com, ritesh.list@gmail.com, hch@infradead.org, djwong@kernel.org, yi.zhang@huawei.com, yi.zhang@huaweicloud.com, yizhang089@gmail.com, libaokun1@huawei.com, yangerkun@huawei.com, yukuai@fnnas.com Subject: [PATCH -next v2 14/22] ext4: implement mmap iomap path Date: Tue, 3 Feb 2026 14:25:14 +0800 Message-ID: <20260203062523.3869120-15-yi.zhang@huawei.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260203062523.3869120-1-yi.zhang@huawei.com> References: <20260203062523.3869120-1-yi.zhang@huawei.com> 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 X-CM-TRANSID: gCh0CgAHaPjnlYFpiadbGA--.27803S18 X-Coremail-Antispam: 1UD129KBjvJXoWxXrWxZF1fGr45Jw17ZrW3GFg_yoW5Krykpr 95KrZ5GrsxZwnI9rs7WFs8Zr15KayxtrW7WrW3Wr13ZFy7t340ga18KF1avF15t3yxAr42 qF4jkF18W3W3ArDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUHqb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E 14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7 xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Y z7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lF7Iv64x0x7Aq67IIx4CEVc8vx2IErcIFxwACI4 02YVCY1x02628vn2kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCF 04k20xvEw4C26cxK6c8Ij28IcwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14 v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_GFv_WrylIxkG c2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVW8JVW5JwCI42IY6xIIjxv20xvEc7CjxVAFwI 0_Gr1j6F4UJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Gr0_ Cr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x07UZyC LUUUUU= Sender: yi.zhang@huaweicloud.com X-CM-SenderInfo: d1lo6xhdqjqx5xdzvxpfor3voofrz/ Content-Type: text/plain; charset="utf-8" Introduce ext4_iomap_page_mkwrite() to implement the mmap iomap path for ext4. Most of this work is delegated to iomap_page_mkwrite(), which only needs to be called with ext4_iomap_buffer_write_ops and ext4_iomap_buffer_da_write_ops as arguments to allocate and map the blocks. However, the lock ordering of the folio lock and transaction start is the opposite of that in the buffer_head buffered write path, update the locking document accordingly. Signed-off-by: Zhang Yi --- fs/ext4/inode.c | 32 +++++++++++++++++++++++++++++++- fs/ext4/super.c | 8 ++++++-- 2 files changed, 37 insertions(+), 3 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 4a7d18511c3f..0d2852159fa3 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4026,7 +4026,7 @@ static int ext4_iomap_buffered_do_write_begin(struct = inode *inode, /* Inline data support is not yet available. */ if (WARN_ON_ONCE(ext4_has_inline_data(inode))) return -ERANGE; - if (WARN_ON_ONCE(!(flags & IOMAP_WRITE))) + if (WARN_ON_ONCE(!(flags & (IOMAP_WRITE | IOMAP_FAULT)))) return -EINVAL; =20 if (delalloc) @@ -4086,6 +4086,14 @@ static int ext4_iomap_buffered_da_write_end(struct i= node *inode, loff_t offset, if (iomap->type !=3D IOMAP_DELALLOC || !(iomap->flags & IOMAP_F_NEW)) return 0; =20 + /* + * iomap_page_mkwrite() will never fail in a way that requires delalloc + * extents that it allocated to be revoked. Hence never try to release + * them here. + */ + if (flags & IOMAP_FAULT) + return 0; + /* Nothing to do if we've written the entire delalloc extent */ start_byte =3D iomap_last_written_block(inode, offset, written); end_byte =3D round_up(offset + length, i_blocksize(inode)); @@ -7135,6 +7143,23 @@ static int ext4_block_page_mkwrite(struct inode *ino= de, struct folio *folio, return ret; } =20 +static vm_fault_t ext4_iomap_page_mkwrite(struct vm_fault *vmf) +{ + struct inode *inode =3D file_inode(vmf->vma->vm_file); + const struct iomap_ops *iomap_ops; + + /* + * ext4_nonda_switch() could writeback this folio, so have to + * call it before lock folio. + */ + if (test_opt(inode->i_sb, DELALLOC) && !ext4_nonda_switch(inode->i_sb)) + iomap_ops =3D &ext4_iomap_buffered_da_write_ops; + else + iomap_ops =3D &ext4_iomap_buffered_write_ops; + + return iomap_page_mkwrite(vmf, iomap_ops, NULL); +} + vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) { struct vm_area_struct *vma =3D vmf->vma; @@ -7157,6 +7182,11 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf) =20 filemap_invalidate_lock_shared(mapping); =20 + if (ext4_inode_buffered_iomap(inode)) { + ret =3D ext4_iomap_page_mkwrite(vmf); + goto out; + } + err =3D ext4_convert_inline_data(inode); if (err) goto out_ret; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index cffe63deba31..4bb77703ffe1 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -100,8 +100,12 @@ static const struct fs_parameter_spec ext4_param_specs= []; * Lock ordering * * page fault path: - * mmap_lock -> sb_start_pagefault -> invalidate_lock (r) -> transaction s= tart - * -> page lock -> i_data_sem (rw) + * - buffer_head path: + * mmap_lock -> sb_start_pagefault -> invalidate_lock (r) -> + * transaction start -> folio lock -> i_data_sem (rw) + * - iomap path: + * mmap_lock -> sb_start_pagefault -> invalidate_lock (r) -> + * folio lock -> transaction start -> i_data_sem (rw) * * buffered write path: * sb_start_write -> i_rwsem (w) -> mmap_lock --=20 2.52.0