From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [117.135.210.3]) (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 D18EB3815E8; Fri, 16 Oct 2026 03:34:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=117.135.210.3 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792121697; cv=none; b=KA2XsTS2hgtrovk0NOFvkRC0pnm4QKTcgXo9JQWPJNBCTkWlsySRwEvG1T5J9xOcquzSkI32qZ5ReEp178PanYov18YdJxqwHfF0XLFOEV1bKHnMfdgruEsf/UnKmT4QNCRMscIGnr4wwidIaZZrSID30LDRABamj0MLwl4UQhY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792121697; c=relaxed/simple; bh=OvLr/KqyPvIPbHR+gRfcxe7WLcbVuuGenvpQHMIemK0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rYX/P73z74xfTnO1cMauh5jjdsC4njN7THR8Qqe8o1IQ4WRhWQAK0ZSjp9Vl7/V5JnkAavrx6+l7EOkTS03dOu4TApmBvHofXTe9HOiYwKJed8uMkRUqWLl8QXBugpD3ckuLhg019Gejqkgxn9cAJcL1fuVP04qqx+U6mBRXwpU= 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=jvIdsN38; arc=none smtp.client-ip=117.135.210.3 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="jvIdsN38" 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=oP lmG3wk4/to/Srmi671CJ/RkvKJSHEyuw0l2n+CfWw=; b=jvIdsN385HvKDAvO07 9iFJI/JI8q/DuwdwEGfyWKgHxzLMb+mnSQ4dY946gEPPHerBeRe2j8za1Ze2+JrB K0GZwqpLxkCJ1aClRKMATl7Hm7hddrSktcycs9LZTEHerMCMiFXxeaNISKowc5uC Rqk3pt3I39rA1vL0UBiPdKOi4= Received: from czl-pc (unknown []) by gzsmtp4 (Coremail) with SMTP id PygvCgDnU5c7m9Fqw1V+AA--.15038S7; Fri, 16 Oct 2026 11:34:23 +0800 (CST) From: Chi Zhiling To: linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, exfat@lists.linux.dev Cc: Namjae Jeon , Sungjong Seo , Yuezhang Mo , Christian Brauner , "Darrick J. Wong" , Christoph Hellwig , Chi Zhiling Subject: [PATCH v3 5/8] exfat: validate cached iomaps during buffered writes Date: Fri, 16 Oct 2026 11:33:46 +0800 Message-ID: <20261016033349.3104509-6-chizhiling@163.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261016033349.3104509-1-chizhiling@163.com> References: <20261016033349.3104509-1-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:PygvCgDnU5c7m9Fqw1V+AA--.15038S7 X-Coremail-Antispam: 1Uf129KBjvJXoWxury8JFyUAw17Aw1DJrWDArb_yoW5AF45pw 4DK3s8GrZ7Xw17Wr13JryrZF1ak34IgF4xArWfG3sxAF1Yyw47KFy8Ka42kF15X34DCr1I qa1vkr48WFn7Cr7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jetCwUUUUU= X-CM-SenderInfo: hfkl6xxlol0wi6rwjhhfrp/xtbC2x8FomrRmz+AqwAA3X 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 10416335e8ee..b25d149f8004 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; @@ -232,6 +233,17 @@ 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) { @@ -244,6 +256,28 @@ 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; +} + /* * exfat_iomap_read_folio_range - Read a block range during a buffered write * @@ -273,7 +307,9 @@ static int exfat_iomap_read_folio_range(const struct iomap_iter *iter, } 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, .read_folio_range = exfat_iomap_read_folio_range, }; -- 2.53.0