From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.5]) (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 3C64E18B0A for ; Sun, 4 Oct 2026 02:59:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791082791; cv=none; b=WbGT5ezESKUzQ3F4DXUbdJI9R8aqCE9PiBEOa6wDRF2jxyHrfbBxFLwh8R4N9A6gPwhgqV+YU+OZsMWnk7XjfQwhUrGEvSZDxpfxD5OJG4Uw/jSXvNcdaVhENYhxByLZx3CJkC1lx7IDVKSm4HA3VNm2qK+WCe6DcQFp1dcdG6g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791082791; c=relaxed/simple; bh=kqaL7ihrMOLXwMT1cXEKvNMh4tLq+4kGfbCXFE0tXLE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=icbGdSV2Lu7RXCQLrZVmYsP9hThm5YZSyQPvy5uyDv+oKW5SCH+naYg/Z5my6ki/HXXx1HqZp4S80mIkoBjyPJ4QxkgUdfkmXW0gwKZYivdrMGrPbcrQZnE87JSQ3BCeRPNVW6f4fh2JjuU2roIv+tFp0WWDw5uwGVNL+FW35/k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=HFvsi1Fi; arc=none smtp.client-ip=117.135.210.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="HFvsi1Fi" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-ID:MIME-Version; bh=8D A33G3PMGkkRtLvHlImnqeYVoOOTU+86ytzFekoRVY=; b=HFvsi1FimOjcIZ/9Hd sbkHP1uXodJVQHhKAO6Mcr3Ih0v51RIImbSqWbBLO4hj1IF/WmC2vByG8evAQ+rl Ua4pqjAvyryiLVko3NMLxJHJomDGl0oZo/EjXET9yzIPkXcUqyvG5wM/i2pWccwL zYTzaohjomCyjUqwUVP7wkOSM= Received: from czl-pc (unknown []) by gzsmtp2 (Coremail) with SMTP id PSgvCgB3HLn9wMFqhREUCg--.6715S3; Sun, 04 Oct 2026 10:59:11 +0800 (CST) From: Chi Zhiling To: exfat@lists.linux.dev, linux-kernel@vger.kernel.org Cc: Yuezhang.Mo@sony.com, dxdt@dev.snart.me, linkinjeon@kernel.org, sj1557.seo@samsung.com, Chi Zhiling Subject: [PATCH 1/4] exfat: advance valid_size to EOF for append writes Date: Sun, 4 Oct 2026 10:59:04 +0800 Message-ID: <20261004025907.1899933-2-chizhiling@163.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261004025907.1899933-1-chizhiling@163.com> References: <20261004025907.1899933-1-chizhiling@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:PSgvCgB3HLn9wMFqhREUCg--.6715S3 X-Coremail-Antispam: 1Uf129KBjvJXoW7CF47Gr1rtF4rGr4kJw4Dtwb_yoW8Kr4fpF Wak3W5ArWIq3y3Gr1xGFs8Z3WrK3Z3trWxX3sYkan8ZrnFyw1fKF1UtFyUKay5t3ykJw4a qa1vyrWDJr17Cw7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UMSoAUUUUU= X-CM-SenderInfo: hfkl6xxlol0wi6rwjhhfrp/xtbC3B96GGrBwP-wmAAA3d From: Chi Zhiling For an append write, the write position is recalculated by generic_write_checks(). Therefore, the write position must be obtained after generic_write_checks() returns. Using the original write position to advance valid_size may cause the valid_size update to be skipped, potentially exposing stale data. Also move the truncate_pagecache() check below the recalculated position, so that pos is never read before it is assigned. Signed-off-by: Chi Zhiling --- fs/exfat/file.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/fs/exfat/file.c b/fs/exfat/file.c index a2a9ee1a2004..b30aec858da6 100644 --- a/fs/exfat/file.c +++ b/fs/exfat/file.c @@ -854,8 +854,7 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) struct file *file = iocb->ki_filp; struct inode *inode = file_inode(file); struct exfat_inode_info *ei = EXFAT_I(inode); - loff_t pos = iocb->ki_pos; - loff_t valid_size; + loff_t pos, valid_size; int err; if (unlikely(exfat_forced_shutdown(inode->i_sb))) @@ -863,11 +862,6 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) inode_lock(inode); - if (pos > i_size_read(inode)) - truncate_pagecache(inode, i_size_read(inode)); - - valid_size = ei->valid_size; - ret = generic_write_checks(iocb, iter); if (ret <= 0) goto unlock; @@ -878,6 +872,11 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) goto unlock; } + pos = iocb->ki_pos; + if (pos > i_size_read(inode)) + truncate_pagecache(inode, i_size_read(inode)); + + valid_size = ei->valid_size; if (pos > valid_size) { ret = exfat_extend_valid_size(inode, pos); if (ret < 0 && ret != -ENOSPC) { @@ -887,6 +886,8 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) } if (ret < 0) goto unlock; + + pos = valid_size; } if (iocb->ki_flags & IOCB_DIRECT) @@ -899,9 +900,6 @@ static ssize_t exfat_file_write_iter(struct kiocb *iocb, struct iov_iter *iter) inode_unlock(inode); - if (pos > valid_size) - pos = valid_size; - if (iocb->ki_pos > pos) { ssize_t err = generic_write_sync(iocb, iocb->ki_pos - pos); -- 2.53.0