From nobody Mon Feb 9 14:15:22 2026 Received: from fra-out-001.esa.eu-central-1.outbound.mail-perimeter.amazon.com (fra-out-001.esa.eu-central-1.outbound.mail-perimeter.amazon.com [18.156.205.64]) (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 A49F7227E83; Tue, 21 Oct 2025 07:11:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=18.156.205.64 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761030675; cv=none; b=HZrfidmMLCRUmV/EYjfcS8Nsx6ueg3XOT/UIm0eWnXyA2SA91gPxuNJhzaTEtyUentPgWqgcLBJtTi1ifEBcd2UHhEH6j6XeBKTIpNPO1d422lzj8m6sgyCp2MJjdSLOBU1V+wr7fbWVrirbxz5qjkvgzQczWXUE00ezoPZP7Kw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761030675; c=relaxed/simple; bh=NedYjdt3harctfQHy2LxknH3Up6TsR4kfMruhCy+Qhw=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=DWFvMEsuOYxk+wrJPIIuZSvsuRrQ3377iu7MJFqu6BG2sVw1ZkgjFL8PEaVG2OVqVtHvROtKSp8Zfdjq2XuPUz3yWw3f4Dh8UZjB1DHlLF7YqT4eMlFSmgb7YbsocLVN2A/O4yx9OustFix84A6IPAJD7CgkH/ja9tU504ydDnE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.de; spf=pass smtp.mailfrom=amazon.de; dkim=pass (2048-bit key) header.d=amazon.de header.i=@amazon.de header.b=rQJv4+T5; arc=none smtp.client-ip=18.156.205.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amazon.de header.i=@amazon.de header.b="rQJv4+T5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.de; i=@amazon.de; q=dns/txt; s=amazoncorp2; t=1761030673; x=1792566673; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=EWT2gm3mr1yTWppm7hvARyuErTtEe+bWsoFO42B5tnI=; b=rQJv4+T5EupMGoyFYEesF8+/V+dC8ClJggBStXH2vNXzu3URTi577vG3 SiuGAIMFAozfFfyM7ifbIVKlCxV+ie2eJJjhxN/f4IVwjea6nSDe0YPy1 +0pSr7hr9YKN9U0DAblQ7Oi8xgiColtPvs3ZCNV1ntQikpfCIpnGhsY/j WhZkAhf5tKGqRR96O7Igz3DPh54S1+gz0x71JSNjT1M4Oa1YVCnWNjDel wyv8nS4gny9qU7eSn0Br9GYXxLrxw8qvpPu7GS62UPF4k6RdfdLuP0QFu NNC6zh5eg1sTRYNtAg+NBmI5pR7EL9EVBG+Bkl7s94zK6Yub93OkShClY w==; X-CSE-ConnectionGUID: DKfSEOkqQQKB8ERoq7WY2A== X-CSE-MsgGUID: DEt+B/AnQgG5Vzyn9KIMpA== X-IronPort-AV: E=Sophos;i="6.19,244,1754956800"; d="scan'208";a="3933276" Received: from ip-10-6-3-216.eu-central-1.compute.internal (HELO smtpout.naws.eu-central-1.prod.farcaster.email.amazon.dev) ([10.6.3.216]) by internal-fra-out-001.esa.eu-central-1.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Oct 2025 07:10:59 +0000 Received: from EX19MTAEUC002.ant.amazon.com [54.240.197.228:11521] by smtpin.naws.eu-central-1.prod.farcaster.email.amazon.dev [10.0.29.7:2525] with esmtp (Farcaster) id 72943488-d8d8-46a1-a014-aaf1f5c61ddd; Tue, 21 Oct 2025 07:10:59 +0000 (UTC) X-Farcaster-Flow-ID: 72943488-d8d8-46a1-a014-aaf1f5c61ddd Received: from EX19D013EUB004.ant.amazon.com (10.252.51.92) by EX19MTAEUC002.ant.amazon.com (10.252.51.245) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Tue, 21 Oct 2025 07:10:59 +0000 Received: from dev-dsk-mngyadam-1c-cb3f7548.eu-west-1.amazon.com (10.253.107.175) by EX19D013EUB004.ant.amazon.com (10.252.51.92) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Tue, 21 Oct 2025 07:10:48 +0000 From: Mahmoud Adam To: CC: , , Christoph Hellwig , Damien Le Moal , Miklos Szeredi , "Darrick J. Wong" , Al Viro , Andreas Gruenbacher , "Anna Schumaker" , Chao Yu , Christian Brauner , Hannes Reinecke , Ilya Dryomov , Jaegeuk Kim , Jens Axboe , Johannes Thumshirn , "Matthew Wilcox" , Miklos Szeredi , "Theodore Ts'o" , Trond Myklebust , Xiubo Li , Andrew Morton , "Jeff Layton" , Andreas Dilger , Christoph Hellwig , Ryusuke Konishi , Luis Chamberlain , , , , , , , , , , Subject: [PATCH 6.1 4/8] fs: factor out a direct_write_fallback helper Date: Tue, 21 Oct 2025 09:03:39 +0200 Message-ID: <20251021070353.96705-6-mngyadam@amazon.de> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251021070353.96705-2-mngyadam@amazon.de> References: <20251021070353.96705-2-mngyadam@amazon.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D038UWB002.ant.amazon.com (10.13.139.185) To EX19D013EUB004.ant.amazon.com (10.252.51.92) Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Christoph Hellwig commit 44fff0fa08ec5a6d9d5fb05443a36d854d0ece4d upstream. Add a helper dealing with handling the syncing of a buffered write fallback for direct I/O. Link: https://lkml.kernel.org/r/20230601145904.1385409-10-hch@lst.de Signed-off-by: Christoph Hellwig Reviewed-by: Damien Le Moal Reviewed-by: Miklos Szeredi Reviewed-by: Darrick J. Wong Cc: Al Viro Cc: Andreas Gruenbacher Cc: Anna Schumaker Cc: Chao Yu Cc: Christian Brauner Cc: Hannes Reinecke Cc: Ilya Dryomov Cc: Jaegeuk Kim Cc: Jens Axboe Cc: Johannes Thumshirn Cc: Matthew Wilcox Cc: Miklos Szeredi Cc: Theodore Ts'o Cc: Trond Myklebust Cc: Xiubo Li Signed-off-by: Andrew Morton [backing_dev_info still being used here. do small changes to the patch to keep the out label. Which means replacing all returns to goto out.] Signed-off-by: Mahmoud Adam --- fs/libfs.c | 41 +++++++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ mm/filemap.c | 61 +++++++++++----------------------------------- 3 files changed, 57 insertions(+), 47 deletions(-) diff --git a/fs/libfs.c b/fs/libfs.c index cbd42d76fbd018..a5bbe8e31d6616 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1582,3 +1582,44 @@ bool inode_maybe_inc_iversion(struct inode *inode, b= ool force) return true; } EXPORT_SYMBOL(inode_maybe_inc_iversion); + +ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter, + ssize_t direct_written, ssize_t buffered_written) +{ + struct address_space *mapping =3D iocb->ki_filp->f_mapping; + loff_t pos =3D iocb->ki_pos - buffered_written; + loff_t end =3D iocb->ki_pos - 1; + int err; + + /* + * If the buffered write fallback returned an error, we want to return + * the number of bytes which were written by direct I/O, or the error + * code if that was zero. + * + * Note that this differs from normal direct-io semantics, which will + * return -EFOO even if some bytes were written. + */ + if (unlikely(buffered_written < 0)) { + if (direct_written) + return direct_written; + return buffered_written; + } + + /* + * We need to ensure that the page cache pages are written to disk and + * invalidated to preserve the expected O_DIRECT semantics. + */ + err =3D filemap_write_and_wait_range(mapping, pos, end); + if (err < 0) { + /* + * We don't know how much we wrote, so just return the number of + * bytes which were direct-written + */ + if (direct_written) + return direct_written; + return err; + } + invalidate_mapping_pages(mapping, pos >> PAGE_SHIFT, end >> PAGE_SHIFT); + return direct_written + buffered_written; +} +EXPORT_SYMBOL_GPL(direct_write_fallback); diff --git a/include/linux/fs.h b/include/linux/fs.h index 4e8a3e4f894c0f..02c83cd07d4f20 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3278,6 +3278,8 @@ extern ssize_t __generic_file_write_iter(struct kiocb= *, struct iov_iter *); extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *); extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *= ); ssize_t generic_perform_write(struct kiocb *, struct iov_iter *); +ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter, + ssize_t direct_written, ssize_t buffered_written); =20 ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *pp= os, rwf_t flags); diff --git a/mm/filemap.c b/mm/filemap.c index e2045266d2f2c9..b77f534dfad35a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3923,25 +3923,21 @@ ssize_t __generic_file_write_iter(struct kiocb *ioc= b, struct iov_iter *from) { struct file *file =3D iocb->ki_filp; struct address_space *mapping =3D file->f_mapping; - struct inode *inode =3D mapping->host; - ssize_t written =3D 0; - ssize_t err; - ssize_t status; + struct inode *inode =3D mapping->host; + ssize_t ret; =20 /* We can write back this queue in page reclaim */ current->backing_dev_info =3D inode_to_bdi(inode); - err =3D file_remove_privs(file); - if (err) + ret =3D file_remove_privs(file); + if (ret) goto out; =20 - err =3D file_update_time(file); - if (err) + ret =3D file_update_time(file); + if (ret) goto out; =20 if (iocb->ki_flags & IOCB_DIRECT) { - loff_t pos, endbyte; - - written =3D generic_file_direct_write(iocb, from); + ret =3D generic_file_direct_write(iocb, from); /* * If the write stopped short of completing, fall back to * buffered writes. Some filesystems do this for writes to @@ -3949,46 +3945,17 @@ ssize_t __generic_file_write_iter(struct kiocb *ioc= b, struct iov_iter *from) * not succeed (even if it did, DAX does not handle dirty * page-cache pages correctly). */ - if (written < 0 || !iov_iter_count(from) || IS_DAX(inode)) + if (ret < 0 || !iov_iter_count(from) || IS_DAX(inode)) goto out; - - pos =3D iocb->ki_pos; - status =3D generic_perform_write(iocb, from); - /* - * If generic_perform_write() returned a synchronous error - * then we want to return the number of bytes which were - * direct-written, or the error code if that was zero. Note - * that this differs from normal direct-io semantics, which - * will return -EFOO even if some bytes were written. - */ - if (unlikely(status < 0)) { - err =3D status; - goto out; - } - /* - * We need to ensure that the page cache pages are written to - * disk and invalidated to preserve the expected O_DIRECT - * semantics. - */ - endbyte =3D pos + status - 1; - err =3D filemap_write_and_wait_range(mapping, pos, endbyte); - if (err =3D=3D 0) { - written +=3D status; - invalidate_mapping_pages(mapping, - pos >> PAGE_SHIFT, - endbyte >> PAGE_SHIFT); - } else { - /* - * We don't know how much we wrote, so just return - * the number of bytes which were direct-written - */ - } - } else { - written =3D generic_perform_write(iocb, from); + ret =3D direct_write_fallback(iocb, from, ret, + generic_perform_write(iocb, from)); + goto out; } + + ret =3D generic_perform_write(iocb, from); out: current->backing_dev_info =3D NULL; - return written ? written : err; + return ret; } EXPORT_SYMBOL(__generic_file_write_iter); =20 --=20 2.47.3 Amazon Web Services Development Center Germany GmbH Tamara-Danz-Str. 13 10243 Berlin Geschaeftsfuehrung: Christian Schlaeger Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B Sitz: Berlin Ust-ID: DE 365 538 597