From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.49 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794556834; b=O68DNg1loBJ3vxTdsVAXYgBazoWFGX70pGeYFynimbso2chpAvKwr+Ztr1E1Ryv2EBXP 4Z4jlWFVd42jxif+4iD5iU2WgjmkPg9FzzrAeyY2iZmMeoPyd79lVlAnI/LGobXHC2iP8 ntuKSXT34csc7HSX8vPohuOAXTO08YVg977cCxs6wCfD8hyn9J/i2BSOXAMGPjVR9hFAd xBVvrMiJANbhZDTZ9+Xtq3jKO120khdPvK4gZSJ0+GfjFRXjyLCt4fEbsHzd2dbKYN492 CN1Fs5bUQ9oeqtSxg6FI7FA9qUklaNLcA15HLEgdbGIJXQnAGBFvAO3eKjNVHNp/wZg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794556834; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:From:To:Cc:Subject:Date:Message-ID: X-Mailer:In-Reply-To:References:MIME-Version: Content-Transfer-Encoding; bh=FJa51iLhuBZSvZgaCQyHA9gsweQVYJTDEV01suKMIE0=; b=5MpHh8qtDT6Wj9iY1bb80eMW7wizLXt3sMKQyf+cNns2kXd59IG8N6cMkDiSYtfRQMri 7jhhcuhJgMJnlgV2E5/Ysf7RCYLhgev+DVK4gtQOcSCOcDQkWKW1LXhfH6AUzeyyU2RyH 3XZIq+mEdKlGdycESi6UwAcvko9NFJ3rCqQcGSG3mjtku8HyUxoiGZazXIE5hb5R3prVO R3FW9IdD3RVV8Ut/8Y6na8Vm1smteNzZb3Vlc22VfVDg0BJjzgRgNG/VNks/2HUKaNPga XXjAytBHCuLosjRfwaglSP7l2gHXvFznkTzU/TUAZmdJIUPkziBAaoxzux7TPTWytHg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Uj27P7sS; arc=none smtp.remote-ip=91.218.175.49 Received: from mta0.migadu.com (out-49.mta0.migadu.com [91.218.175.49]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DEBF6606A31C for ; Fri, 13 Nov 2026 08:00:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org DEBF6606A31C Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Uj27P7sS X-Envelope-To: stable@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=7f/HfuvjReljqnkx1PiPbyRP13u071+OBhrkb2fzJn0=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794556831; v=1; x=1795161631; b=Uj27P7sSyQz1dIHNZPj/+ON3Ac+auHqKW0BMmEmuQVEwG185KoeIVYm/lgjuGjdWnbi5Pcbc CBBLOcDygtup77pvCE9Lv4LcECzdLW64L+FdO0py492cU97iRC6lnrR3jI2WmTejNiorI0wtq/Y +G5OjPB+O9X/GEeqDo/FUo6M= X-Envelope-To: stable@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id a9fb94107abe5fe3; Fri, 13 Nov 2026 08:00:31 +0000 X-Mizu-Trace-ID: a9fb94107abe5fe3 X-Migadu-Flow: FLOW_OUT From: Youling Tang To: youling.tang@linux.dev Cc: Youling Tang , stable@vger.kernel.org Subject: [PATCH 1/2] exfat: fix iomap mapping when writeback races with truncate Date: Fri, 13 Nov 2026 16:00:12 +0800 Message-ID: <20261113080013.2432300-2-youling.tang@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261113080013.2432300-1-youling.tang@linux.dev> References: <20261113080013.2432300-1-youling.tang@linux.dev> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Youling Tang __exfat_iomap_begin() reads i_size twice: once to detect a range that starts beyond EOF, and once to clamp the mapping to EOF. A concurrent truncate can shrink i_size between the two reads, so the clamp can produce a negative length. The unsigned cluster index subtraction then underflows, making exfat_map_cluster() believe it has to allocate a huge number of clusters and report a hole. Fix this by reading i_size once for both the EOF check and the block-aligned clamp. Fixes: 82a81a7352bc ("exfat: add iomap buffered I/O support") Cc: stable@vger.kernel.org Signed-off-by: Youling Tang --- fs/exfat/iomap.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/exfat/iomap.c b/fs/exfat/iomap.c index 4e6f3ed9dcc8..11823591b3a8 100644 --- a/fs/exfat/iomap.c +++ b/fs/exfat/iomap.c @@ -51,8 +51,10 @@ static int __exfat_iomap_begin(struct inode *inode, loff_t offset, loff_t length bool balloc = false; if (!may_alloc) { + loff_t isize = i_size_read(inode); + /* Completely beyond EOF. Treat as hole */ - if (i_size_read(inode) <= offset) { + if (offset >= isize) { iomap->type = IOMAP_HOLE; iomap->addr = IOMAP_NULL_ADDR; iomap->offset = offset; @@ -61,9 +63,8 @@ static int __exfat_iomap_begin(struct inode *inode, loff_t offset, loff_t length } /* Clamp length if the requested range goes beyond i_size */ - if (offset + length > i_size_read(inode)) - length = round_up(i_size_read(inode), - i_blocksize(inode)) - offset; + if (offset + length > isize) + length = round_up(isize, i_blocksize(inode)) - offset; } num_clusters = exfat_bytes_to_cluster_round_up(sbi, -- 2.43.0