From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.5]) (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 6170147D44F for ; Tue, 13 Oct 2026 03:39:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791862784; cv=none; b=lxPcBP1VUvsiIzQofxc9qPjSII8Min/CTF5sxlI3mjthIEuenixGGiQTXsfsEw1/tCmyPzwqdQaEZ7U6+eg57yERg/5xIXNVuMzgFfFWONABWNVtgis2SmeHj+0q/VhnaIkOV5QdCAEb33thlb263fVLaUIQAKe1rjt42t7rACk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791862784; c=relaxed/simple; bh=erfosRWPTFvOsGU4ezdaOnyZtAcxyQVrWAsDL5HRRGg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CvMeanSON+kajzh1zk36BJ+seyr+teJW/IK3P+OC5o+epHvfNO+fu3gBObNEXqhZjPnm/HChzKUOt29XaWX4zsZH0AfsPgUK0S4A+mMStrKCF4Rl3AoFI6pO3E+pQtddthTUamzTSDp7HVKgRVH/k84BqMV6jeobeSQzc7Diacg= 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=cONBi+7H; arc=none smtp.client-ip=220.197.31.5 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="cONBi+7H" 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=1B IiVmEsqhgE22RBFOG7HF+qpOGjbt7+PXa7kkCXNkU=; b=cONBi+7H+nWz1wFSFC uO8Vx/yIoGrQ3TCI9ZT/OyAqqMHRD+P50+LGkwN9O6HM9orblJ0221IotZ3k6eQk gLew5fCCO0MAlVbtI6DUEQMArNXuDzWBWh9wvgHxxcSw3eFIyToukN3OAj1+TF6Z CMzqz1zCOiRbcldeYAng10eBQ= Received: from czl-pc (unknown []) by gzga-smtp-mtada-g1-3 (Coremail) with SMTP id _____wD3fwTKp81qBFXLEQ--.23138S5; Tue, 13 Oct 2026 11:38:54 +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 v2 3/7] exfat: validate cached iomaps during buffered writes Date: Tue, 13 Oct 2026 11:38:33 +0800 Message-ID: <20261013033837.2748258-4-chizhiling@163.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261013033837.2748258-1-chizhiling@163.com> References: <20261013033837.2748258-1-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:_____wD3fwTKp81qBFXLEQ--.23138S5 X-Coremail-Antispam: 1Uf129KBjvJXoWxury8JFyUAw17Aw1DJrWDArb_yoW5XF4fpw s8K3s8GrZ3W3W7Wr13JryrZF1a934IgF4xArWfG3sxAFyYyw47KFy8Ga42kF15X34DCr1I qa1vkF48WFn7Cr7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jd0eQUUUUU= X-CM-SenderInfo: hfkl6xxlol0wi6rwjhhfrp/xtbC2w4ryGrNp86OvAAA3K From: Chi Zhiling The next patch, "exfat: drop i_rwsem from exfat_page_mkwrite()", allows a fault to advance valid_size under the folio lock without serializing against an in-flight buffered write. As a result, valid_size may advance into a folio covered by a cached iomap. Reusing that iomap would cause __iomap_write_begin() to zero the wrong part of the block. Add an ->iomap_valid callback that compares ->validity_cookie against the current valid_size and forces a remap if valid_size has advanced into the locked folio, whose pointer is stored in ->private by ->get_folio. Signed-off-by: Chi Zhiling --- fs/exfat/iomap.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/fs/exfat/iomap.c b/fs/exfat/iomap.c index f3816509c6e5..26d216ef9c44 100644 --- a/fs/exfat/iomap.c +++ b/fs/exfat/iomap.c @@ -57,6 +57,7 @@ static int __exfat_iomap_begin(struct inode *inode, loff_t offset, loff_t length iomap->addr = IOMAP_NULL_ADDR; iomap->offset = offset; iomap->length = length; + iomap->validity_cookie = valid_size; return 0; } @@ -145,7 +146,7 @@ static int __exfat_iomap_begin(struct inode *inode, loff_t offset, loff_t length } } - iomap->flags |= IOMAP_F_MERGED; + iomap->validity_cookie = valid_size; out: mutex_unlock(&sbi->s_lock); return err; @@ -252,6 +253,17 @@ const struct iomap_ops exfat_write_iomap_ops = { .iomap_next = exfat_write_iomap_next, }; +static struct folio *exfat_iomap_get_folio(struct iomap_iter *iter, loff_t pos, + unsigned int len) +{ + struct folio *folio = iomap_get_folio(iter, pos, len); + + if (!IS_ERR(folio)) + iter->iomap.private = folio; + + return folio; +} + static void exfat_iomap_put_folio(struct inode *inode, loff_t pos, unsigned int copied, struct folio *folio) { @@ -264,8 +276,32 @@ static void exfat_iomap_put_folio(struct inode *inode, loff_t pos, folio_put(folio); } +static bool exfat_iomap_valid(struct inode *inode, const struct iomap *iomap) +{ + struct folio *folio = iomap->private; + loff_t old_valid_size = iomap->validity_cookie; + loff_t valid_size = exfat_get_valid_size(EXFAT_I(inode)); + + if (valid_size == old_valid_size) + return true; + + if (!folio) + return false; + + /* Still valid for this folio. */ + if (old_valid_size >= folio_next_pos(folio)) + return true; + + if (valid_size <= folio_pos(folio)) + return true; + + return false; +} + const struct iomap_write_ops exfat_iomap_write_ops = { + .get_folio = exfat_iomap_get_folio, .put_folio = exfat_iomap_put_folio, + .iomap_valid = exfat_iomap_valid, }; /* -- 2.53.0