From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.8 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793862016; b=OSpxQ7GhyaaSpeE1aQPq4UCh9sYYbgPGvaoiosd8W8aaoWQ2UdoAFGdvfXdlv2Xjav+B OUYRL6Oueg8FUAP5keasc1R/vviwpNouazE80nei+FMK5cUPAuPUG1VWXdeulcVJs/eok UFg+s64MmBhgNjxOEiBcK48d44lxoVDOQZaatoZzJQ/8AQ00VhiwztxZ5winINozR3arY i/kixfCD6UMV/qshum0NKoGqb/ir/cQV9GB6SIu8pZapVkrUyzzZuOTf/LwWhYf+VmNr0 GVMKj/ei9TRHShAfWYKAFoOBYHb5bvXVooh+YtDUNNMVjDazM1bX9gQUWgkm95S9m/g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793862016; 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=0wrzHtFxjFXd7iU05CW3/ydQ7QCAtEugjeoklBp7xpE=; b=tIXMBx7VtVTQPqOF5cKoF6fQn4BDxMHmTbKy9nDTOsNOrYmvaLs55CLtF0swC/zZETEW ZEVMJKJLNPEOEDs0Lu7+rWelVkI4hxRtwMb9rPdIFTUs2Avt2oRVv0Yc7ko0cZqMqku0V Spp6uVOWiQksXaA2JVmtIJxlLcJxWTUhWRHbV0NTf/XZzRSoDDEntibOPNDEJ15pNO79d gqJj2n/CFzkU29/riKl8/mOzrHy1AJ8gG3DDC5B4NYqRp7irv4l+PWvqotvAodKQRxxSM gLzY//U4JpXWyEcss+SChwJA2xLa/4AxzJV44AEzXZPslkOci/mqO8c1GVX6BOUI2+w== 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=gu3dXD8o; arc=none smtp.remote-ip=95.215.58.8 Received: from mta1.migadu.com (out-8.mta1.migadu.com [95.215.58.8]) (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 DC0F7606A339 for ; Thu, 5 Nov 2026 07:00:07 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org DC0F7606A339 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=gu3dXD8o X-Envelope-To: linux-block@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=ax+wsuHoy6H96hgXiHuF6MzNsH6ADwaKJZJ1/7kMLiA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793862006; v=1; x=1794466806; b=gu3dXD8ovEhih0rAWmev6W2AOFR/IDaEehfUUFgeNq3wirBmvDlKHAqm5p/Tz+SA1BiOQuOG qCkwAa3XXnNoqIpcTagxmPi0o24Eif2ZmOzorQBk0pIqEJNSX3rILgB0r5bQ7BLrRzLo2c1K3q2 2yZoCEZ1tjhFvPYpMUYTiwmY= X-Envelope-To: linux-block@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 96e1fbcbd6d57c1a; Thu, 05 Nov 2026 07:00:05 +0000 X-Mizu-Trace-ID: 96e1fbcbd6d57c1a X-Migadu-Flow: FLOW_OUT From: Mengmeng Zhao To: Jens Axboe , Dan Williams , Matthew Wilcox , Jan Kara , Alexander Viro , Christian Brauner , tytso@mit.edu, Andreas Dilger , Baokun Li , Ojaswin Mujoo , "Ritesh Harjani (IBM)" , Zhang Yi , "Darrick J. Wong" , Andrew Morton , asml.silence@gmail.com, hch@lst.de, Anuj Gupta 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-mm@kvack.org, Li Wang Subject: [RFC 4/6] iomap: refuse dmabuf iterators in iomap_file_buffered_write() Date: Thu, 5 Nov 2026 14:58:45 +0800 Message-ID: <20261105065847.196540-5-mengmeng.zhao@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261105065847.196540-1-mengmeng.zhao@linux.dev> References: <20261105065847.196540-1-mengmeng.zhao@linux.dev> X-Mailing-List: linux-block@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: Mengmeng Zhao A buffered write copies through the CPU linear address, which a device mapping cannot provide. fault_in_iov_iter_readable() treats a dmabuf iterator as always readable, so the copy fails with a WARN_ON_ONCE from iterate_and_advance2() and iomap_write_iter() retries the unchanged remainder forever. Refuse the iterator at the entry with -EOPNOTSUPP, as generic_perform_write() and the generic read paths already do, so that every generic buffered copy helper turns the iterator away before touching the page cache. Signed-off-by: Mengmeng Zhao Signed-off-by: Li Wang --- fs/iomap/buffered-io.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 0a5ebfda90f1..3f56bd225e8c 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1304,6 +1304,13 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i, }; ssize_t ret; + /* + * A buffered write copies through the CPU linear address, which a + * device mapping cannot provide. + */ + if (iov_iter_is_dmabuf_map(i)) + return -EOPNOTSUPP; + if (iocb->ki_flags & IOCB_NOWAIT) iter.flags |= IOMAP_NOWAIT; if (iocb->ki_flags & IOCB_DONTCACHE) -- 2.43.0