From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=91.218.175.199 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794553640; b=Rh4hnyjoTP/MXLpOv8fQFMl2ZEmftSEGWcAX/jy9nLytFOy69LCDSLMlbUW8pyIthfA0 wmVrvNVNxPBQlmlKaXl4/i9Q6lFv2gIkKOS/U7ixk+XwyxHpdfmZT2Tr1jfkSx4Lbb6bo y8mjFM2g/IvJdD2GDLFlHnpjMmJFeQJ+rWagoL2Y6algLtqZlQ5nwBYrfoQicnWupzMzH 0KflXfDiAFdNEKDp1rXL19CS3nWvFs+PcnvOEesDrUTg/mJVko/9WDpkC7uwrOGm6CsVh cuUyfjR0TYR0CriKNzq+HxbmZQkCodsrgc+5XG8ZBVpQ7lX2kigO3RFGyK/RjLaGZGw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794553640; 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=GZLtnWbFqtu8KIap5fiJtQhx6w9LpQFKds01tBdh2l0=; b=XwdcweV0n+St/3ft0s0DUgHstcjuQiXc8WgGOC6lXb1AVCkAOB6VHsEsSE/+Z6Kq3Jkv Di0U3lEo7NAzxOoj1g7+Pwh5fSL4M9gI9RLPO3M82XzktzJ07xxGc85IJavOpRtwLPptu jxR0bxiWxSEcEXgPeQloL9Ldb2XZm9seS2K0HjoGLV46V1HH0oNONzkhWaxeQdJq8pmTQ lDEsnjU225sZXnkaTJalePchIjLLN2C4HuDTw+Edg4mWpYkYeICQH1Hx05GLXEGTFM6Cy WTQwzaeXQXQTJAqFPSP8nMpryfMCuxALPVwL5Wj4pUqrzWiE7d8Ux4fSOHAM0XoHxyQ== 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=u64wSiXr; arc=none smtp.remote-ip=91.218.175.199 Received: from mta0.migadu.com (out-199.mta0.migadu.com [91.218.175.199]) (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 C4B17606A8AF for ; Fri, 13 Nov 2026 07:07:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org C4B17606A8AF 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=u64wSiXr X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=wulpxDchqVhG4T16i7jOp2tJVbBXi1laAGjfm4w5eGs=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794553638; v=1; x=1795158438; b=u64wSiXr9YoxMTLiiPFG3x6j3X+qgKk4U2wB14aAvE5z2X/c+S+lLtx4APm9yuZmji9smYZx JXNVHCFIMmI7BEQbjNZO1fFwEpVeXYwFKUXVySSIg8MwGOYR4Ol1tMGrDjAmdqHWugAal+GarUR NcCSZkR+A1fKd3JgXQ66mWBM= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id d2229d58c56c6432; Fri, 13 Nov 2026 07:07:17 +0000 X-Mizu-Trace-ID: d2229d58c56c6432 X-Migadu-Flow: FLOW_OUT From: Mengmeng Zhao To: Christoph Hellwig , Anuj Gupta , Nitesh Shetty , Jens Axboe , Sumit Semwal , christian.koenig@amd.com, Philipp Stanner , Dan Williams , Matthew Wilcox , Jan Kara , Alexander Viro , Christian Brauner , tytso@mit.edu, Andreas Dilger , Baokun Li , Ojaswin Mujoo , "Ritesh Harjani (IBM)" , Zhang Yi , asml.silence@gmail.com, Jonathan Corbet , Shuah Khan , Randy Dunlap Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, linux-doc@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, Li Wang , Mengmeng Zhao Subject: [RFC PATCH v2 2/8] iomap: add dma-buf direct I/O guards Date: Fri, 13 Nov 2026 15:06:15 +0800 Message-ID: <20261113070621.273953-3-mengmeng.zhao@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261113070621.273953-1-mengmeng.zhao@linux.dev> References: <20261113070621.273953-1-mengmeng.zhao@linux.dev> X-Mailing-List: linux-kernel@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: Nitesh Shetty Direct I/O copies data from the CPU in four places, zero-filling holes, inline data, bounce pages and integrity metadata. A dma-buf iterator has no pages behind it, so refuse it there. Reads that encounter a hole or unwritten extent therefore return -EOPNOTSUPP for the entire operation, even if I/O for an earlier mapped extent was already submitted. Signed-off-by: Nitesh Shetty Signed-off-by: Anuj Gupta Signed-off-by: Mengmeng Zhao Signed-off-by: Li Wang --- fs/iomap/direct-io.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index ad041ac3252a..4a2b0f9df5a7 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -425,6 +425,11 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio) unsigned int alignment; ssize_t ret = 0; + /* integrity metadata is generated from the data pages */ + if (iov_iter_is_dmabuf_map(dio->submit.iter) && + (iomap->flags & IOMAP_F_INTEGRITY)) + return -EOPNOTSUPP; + /* * File systems that write out of place and always allocate new blocks * need each bio to be block aligned as that's the unit of allocation. @@ -589,7 +594,13 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio) static int iomap_dio_hole_iter(struct iomap_iter *iter, struct iomap_dio *dio) { - loff_t copied = iov_iter_zero(iomap_length(iter), dio->submit.iter); + loff_t copied; + + /* zero-filling walks the data pages */ + if (iov_iter_is_dmabuf_map(dio->submit.iter)) + return -EOPNOTSUPP; + + copied = iov_iter_zero(iomap_length(iter), dio->submit.iter); if (dio->flags & IOMAP_DIO_FSBLOCK_ALIGNED) { loff_t aligned_copied = round_down(copied, @@ -619,6 +630,10 @@ static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio) loff_t pos = iomi->pos; u64 copied; + /* inline data is copied from the CPU */ + if (iov_iter_is_dmabuf_map(iter)) + return -EOPNOTSUPP; + if (WARN_ON_ONCE(!inline_data)) return -EIO; @@ -717,6 +732,10 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, if (!iomi.len) return NULL; + /* bouncing copies the data from the CPU */ + if (iov_iter_is_dmabuf_map(iter) && (dio_flags & IOMAP_DIO_BOUNCE)) + return ERR_PTR(-EOPNOTSUPP); + dio = kmalloc_obj(*dio); if (!dio) return ERR_PTR(-ENOMEM); -- 2.43.0