From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f43.google.com (mail-wm1-f43.google.com [209.85.128.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 593053815E8 for ; Wed, 29 Apr 2026 15:26:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.43 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777476395; cv=none; b=j2HUSBzi1ha5VddpNF/C78L8rXc6BMQ80U+Ka8P4D3x9VFTP9QLQhWwdlFEwD1nPbEqgvO5QvxbAtoGhB7KoDYd/vqlyj4lwUyXPKJJSVCqE27kX5kghRgzdrpfnuUR24TspA1phKHiLaT6m3Hs+e9nFEC56YgPEYRKh9iILObk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777476395; c=relaxed/simple; bh=CNs/Yxbm5MZEeW58x4HT0ka3sUBh+wiGFZ1q5uz6Eyg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=M+hDYe3cPFPQUsty7orbs6MK52j0ko7IkiBW8kjvEWkfT4sN53/3MuaC1wFkaXiyKDrTWoFnlUOvE37rUzzRzvctaUlC4aTjIcnAABe9YgAR86Ad85kX5HYsJ2GBsnbTFgFCKsYlKU5J2dMNCnJPIVaX40HROLQQZMvHEM9cZf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=RAXK9GyR; arc=none smtp.client-ip=209.85.128.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="RAXK9GyR" Received: by mail-wm1-f43.google.com with SMTP id 5b1f17b1804b1-488b0e1b870so220287265e9.2 for ; Wed, 29 Apr 2026 08:26:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1777476389; x=1778081189; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=wYUNmBP6U3FeRokeO7r7d75tv9vLUxF9835eHvzSe1g=; b=RAXK9GyRu97bc5WOLSH+4gh1auoZTmpa1HqX78LaANkYEjuGMxYtdmGzrscRlggjBu FI3MsWnBF3K0c0J/xBIYa+adAOw5BsKftyc1EPzIn8JGIRtL7jqGBntr6V5PzM7K30/D ivK00yx75TjAMKw60V5vtbYCC/qAlhBTy4Q4xIqoeQx5uozrlsf0y1angULIyPkwyaeG yAxohAfltZlkqdgnlN0d0y14nTPr5JAZqtpAddVndfInu54FrdPpttKn6nwzBZX4XZV0 Be3oCXsLQR05Bnj4njUgZL2x+U6oIgTBvRou2ue8Q47n0uxfFeQ5R+drvSVYb84N0Dgl NEMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777476389; x=1778081189; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=wYUNmBP6U3FeRokeO7r7d75tv9vLUxF9835eHvzSe1g=; b=ayEN6RitwWeMmekvOoLDv6frqUlw2mlOHhpSnMz4fp7BPrx24OW3lfUk2icABobTa1 ZwRxcOKX1f/2UuTUx7SkryrnQCosC3n+oPPl9MlgsOtjSPW5lG+iKP04S9s8k6fhUns/ dz0NpYxBHZERDnaiLsvy4VeOlY8qHhCx8kXdMCJGdQnbHOk7PvmYOZJb0Tn7SbQBEsDs +1fl07o6nMic/KVGA+8r1gzBsRkKcfJTeSVdhOxDBzuF7iLVzXyKp3ItmUe7uP5eC8kJ DpL8XSKN5LWL4b6eVtZISzOsrdVlTUkLzDJ4+OUugu+5LyUW/NOvLpmqZcX/SULbsei1 XRQw== X-Forwarded-Encrypted: i=1; AFNElJ+KnKDBGYNDZCPdrhUwHvAex1PYK4D3I/K/EnEGsKObsonci4KeQKBYG1Uieq4ty3Wq7JRgWQIFh8VkfQIa@vger.kernel.org X-Gm-Message-State: AOJu0YwZhoYsSzw/CDnw9JEyaeeP4vJ50aX7Wc2L0bTb23g9veVgG1SZ EKcSw/pklj5yFroI5ogm+249UncWfgVcta2vQLrR08uNjn4nNfx2SnV8 X-Gm-Gg: AeBDiesgJ2MQZ/3SzbsQtNlo1hauggMmxdQw82LBbZSre0+acGvKkWmrm6N3qQEXfjB VbM877ZGGkaMiGv0ZAfj0ioNrXPch0KCBJM6bplhXJEUP+0WBBxSUamaFi/Nk5OaZLPKRWbUyV5 9YVBNCB69MaTgeEZpUwL8PCKofy1T8Pm2sOFT6OEtJf3QHBfXws9zp4AcaG6tCcY1ezurGc0bG5 MOwCasDizODKL2QkyKoCmNEl/ReBt49/VeEUiZnlOomlwjPR4KJT4xL37daD2fxlWdQ2JzzBZym /8w4Kb9l8nwYqI0D/aNI7qzJzA+LaY3NZ3xXwuBF/EEZqhifDlAUrNuTekD2ADOTLmJWIBmLERH Ylw66QqKKl4SXCLITFwhQceBoXF4280L30xsxWJA8aPiAV7xd4ZpHc2yel+hCAbBaGbgtgrNeLD y7NyY7wpuU+ZaUO7Z+o7ru+YOA8nlSw9YKtvFOPqq4N2rO/f11HUOCzQ5tlGUAY+jzJ2FkI37Jg s9CaYdSB1y8ulReSmjkRy67PQaeXwP7Pj9D8iPzQuIdXh30vS7BL8Q= X-Received: by 2002:a05:6000:26cb:b0:43f:de5a:eb63 with SMTP id ffacd0b85a97d-4478ea89a58mr8097281f8f.11.1777476388358; Wed, 29 Apr 2026 08:26:28 -0700 (PDT) Received: from 127.0.0.1localhost ([82.132.184.31]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-447b76e5c22sm6382951f8f.28.2026.04.29.08.26.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Apr 2026 08:26:27 -0700 (PDT) From: Pavel Begunkov To: Jens Axboe , Keith Busch , Christoph Hellwig , Sagi Grimberg , Alexander Viro , Christian Brauner , Andrew Morton , Sumit Semwal , =?UTF-8?q?Christian=20K=C3=B6nig?= , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org Cc: asml.silence@gmail.com, Nitesh Shetty , Kanchan Joshi , Anuj Gupta , Tushar Gohad , William Power , Phil Cayton , Jason Gunthorpe Subject: [PATCH v3 02/10] iov_iter: add iterator type for dmabuf maps Date: Wed, 29 Apr 2026 16:25:48 +0100 Message-ID: <20a233d2f35274817aa643cc0fe113707eb47e72.1777475843.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Introduce a new iterator type for dmabuf maps. The map in an opaque object with internals and format specific to the subsystem / driver, and only it can use that subsystem / driver for issuing IO. The task of the middle layers is to pass the map / iterator further down, maybe doing basic splitting and length checking. The iterator can only be used by operations of the file the associated map was created for. Suggested-by: Keith Busch Signed-off-by: Pavel Begunkov --- include/linux/uio.h | 11 +++++++++++ lib/iov_iter.c | 29 +++++++++++++++++++++++------ 2 files changed, 34 insertions(+), 6 deletions(-) diff --git a/include/linux/uio.h b/include/linux/uio.h index a9bc5b3067e3..75051aed70de 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -12,6 +12,7 @@ struct page; struct folio_queue; +struct io_dmabuf_map; typedef unsigned int __bitwise iov_iter_extraction_t; @@ -29,6 +30,7 @@ enum iter_type { ITER_FOLIOQ, ITER_XARRAY, ITER_DISCARD, + ITER_DMABUF_MAP, }; #define ITER_SOURCE 1 // == WRITE @@ -71,6 +73,7 @@ struct iov_iter { const struct folio_queue *folioq; struct xarray *xarray; void __user *ubuf; + struct io_dmabuf_map *dmabuf_map; }; size_t count; }; @@ -155,6 +158,11 @@ static inline bool iov_iter_is_xarray(const struct iov_iter *i) return iov_iter_type(i) == ITER_XARRAY; } +static inline bool iov_iter_is_dmabuf_map(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_DMABUF_MAP; +} + static inline unsigned char iov_iter_rw(const struct iov_iter *i) { return i->data_source ? WRITE : READ; @@ -300,6 +308,9 @@ void iov_iter_folio_queue(struct iov_iter *i, unsigned int direction, unsigned int first_slot, unsigned int offset, size_t count); void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray, loff_t start, size_t count); +void iov_iter_dmabuf_map(struct iov_iter *i, unsigned int direction, + struct io_dmabuf_map *map, + loff_t off, size_t count); ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages, size_t maxsize, unsigned maxpages, size_t *start); ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages, diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 243662af1af7..e2253684b991 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -575,7 +575,8 @@ void iov_iter_advance(struct iov_iter *i, size_t size) { if (unlikely(i->count < size)) size = i->count; - if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i))) { + if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i)) || + unlikely(iov_iter_is_dmabuf_map(i))) { i->iov_offset += size; i->count -= size; } else if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) { @@ -631,7 +632,8 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll) return; } unroll -= i->iov_offset; - if (iov_iter_is_xarray(i) || iter_is_ubuf(i)) { + if (iov_iter_is_xarray(i) || iter_is_ubuf(i) || + iov_iter_is_dmabuf_map(i)) { BUG(); /* We should never go beyond the start of the specified * range since we might then be straying into pages that * aren't pinned. @@ -775,6 +777,20 @@ void iov_iter_xarray(struct iov_iter *i, unsigned int direction, } EXPORT_SYMBOL(iov_iter_xarray); +void iov_iter_dmabuf_map(struct iov_iter *i, unsigned int direction, + struct io_dmabuf_map *map, + loff_t off, size_t count) +{ + WARN_ON(direction & ~(READ | WRITE)); + *i = (struct iov_iter){ + .iter_type = ITER_DMABUF_MAP, + .data_source = direction, + .dmabuf_map = map, + .count = count, + .iov_offset = off, + }; +} + /** * iov_iter_discard - Initialise an I/O iterator that discards data * @i: The iterator to initialise. @@ -841,7 +857,7 @@ static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i) unsigned long iov_iter_alignment(const struct iov_iter *i) { - if (likely(iter_is_ubuf(i))) { + if (likely(iter_is_ubuf(i)) || iov_iter_is_dmabuf_map(i)) { size_t size = i->count; if (size) return ((unsigned long)i->ubuf + i->iov_offset) | size; @@ -872,7 +888,7 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i) size_t size = i->count; unsigned k; - if (iter_is_ubuf(i)) + if (iter_is_ubuf(i) || iov_iter_is_dmabuf_map(i)) return 0; if (WARN_ON(!iter_is_iovec(i))) @@ -1469,11 +1485,12 @@ EXPORT_SYMBOL_GPL(import_ubuf); void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state) { if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i) && - !iter_is_ubuf(i)) && !iov_iter_is_kvec(i)) + !iter_is_ubuf(i) && !iov_iter_is_kvec(i) && + !iov_iter_is_dmabuf_map(i))) return; i->iov_offset = state->iov_offset; i->count = state->count; - if (iter_is_ubuf(i)) + if (iter_is_ubuf(i) || iov_iter_is_dmabuf_map(i)) return; /* * For the *vec iters, nr_segs + iov is constant - if we increment -- 2.53.0