From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f54.google.com (mail-ej1-f54.google.com [209.85.218.54]) (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 E7A4B2E8E0D; Fri, 27 Jun 2025 15:09:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751036968; cv=none; b=HPdpUMiiPftF+I8jKOO2ErmePvOtVRTikg7NJoqbMNypmfCs62aiZS1+wzWeM2bLwPeyKJvzw3kKXF+Y9PygTh1uG23jpjlE5pFnbVr/Kq0Aijs9bcFUM7XS1CfdzlZ0jgNM5iVKgQCi/U52vvtEndoGZZwnsQWUwSUvPdALaA0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751036968; c=relaxed/simple; bh=KWDxPLsGnbk8fG+WmvbBXC/yc19sBb4Gy8Sd+JE5e1A=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=riXeRmUxV66IIsO1+vxEY93JBB3zSXIQo6IWD7m9CaRKOS4BoNBXCSs1VYdEyQVG+sgkt1WtFiobv6JC+hgiGgtvhS9/zDERhGrloM6zRhOnEc903gvcZiMcP8YFOUfiX7dFFE0k89Ya6VE402aZG5Vbr/sL0eLiX3jEbYasyrU= 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=UzrBqIG2; arc=none smtp.client-ip=209.85.218.54 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="UzrBqIG2" Received: by mail-ej1-f54.google.com with SMTP id a640c23a62f3a-ae0a420431bso438489666b.2; Fri, 27 Jun 2025 08:09:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1751036965; x=1751641765; 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=RpWD4+kMQgcu38VQMZMvjMOGf7VzHXvFZWMDq5klZzA=; b=UzrBqIG2Hsx3LhQtLr0tsgQ03KqGywJ4p1q5dZeEOpJ7OrQkOvciZdsMyKAFZRxkAm okUNGqZXdFUqnWInDTgpLMgdRNHHbAXRw3KcaPc3F5n7422Rsen54IBA0PK7bQRC5LK8 lQgMnbTGAwE1v7rvcSaup2hTjlKtnuPWFQAyDSxs8Ghvo08+/xxOECfxXUd+Q4/0rxn1 QG9JnlPSLzhs71o3zUnAYx1ZA5tHRmuf/M5ASxnXHPfyp1252vqLGcaOiS/i2hX5LKYV TEgs81/v6iuPCd7Ql6lsWXsV3v53mgCBz19tfnTw8OY9ugqzeuP2OqhcrYYsIvazXFiu Gqyw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751036965; x=1751641765; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=RpWD4+kMQgcu38VQMZMvjMOGf7VzHXvFZWMDq5klZzA=; b=fUL+3U2w68SVDVVMQvJm9IqOe8piBpA/e1gZHRweLL3js3cM0atNNieU2zhYqVZ8Yw 4LCCWZCwCIIu3pkM7m6XLCX/VE5U4q0P+TMgZQI21WnCfNgGmW/UOYaIOS6QvzIATZJp SRiIUWh7ofA+5Ld6KCqxD6VPeO+2kamXt1Cxh2C7WCqq8FCYZTyEmH+LRZckKqJlJjZv carirJUxQa3XatPLtn2DiP4Ach4BqRz0ZluUh01GPy1VeMsCmngXal7N+NCho0ShPATH ktEX8lt5TrUe4XRvidFr+HgbO1flndGZ1SnpRdalnP1IuzcsLzWLBSlFqrx4nLcIpCe2 Fe9A== X-Forwarded-Encrypted: i=1; AJvYcCUSijXhXUnsKIO1wVK+bJyxcVaFD2WrXj6IU7Nhw2qaX1aqCvjlb80ulKpCeKeThpvh79khB9v+oyB+ng==@vger.kernel.org X-Gm-Message-State: AOJu0YyHU2I2/FAXGH+WTmq3GMsWKH66dvKIF56f81yQWNLOHXNmS9R2 IgKPs4r0l35basAST6LV8nbV7Sr4+Bdn7sfXsSf8gXBqznBCE4+aSsENkrlKVA== X-Gm-Gg: ASbGncuiuyuT4eoBAL277Jlw4hPoCCGzmCS/sFzfLim76pjRNWoU/0fR23uABi+2bNK YkC2tAWI+KcjNtYf7TlIxYBcobkvezdeWecQ2v2jiQMduR+6Dh0YkmTJiTnkQ/6dLx1GreE9R4G JAkRqBFpZWROhv1USmfhuNLLDqyXNFC2dA1yJ4BK02wJeF0vkdrFuEZHbukzKNoykaWXXPIPMbz qeQWHgDhgvC+0lcNNpU7aIFxMFX5FWX8LZrFss4R7aQ2S2p0CU2hwywdBJ6iGeRtJfLYxdecv9f ikRpXzsQpsP791DK/e70oV8O18KGszm/mZfb1EV1TD1bCiBDy1jYLhVHbLPgO9BpkkU1HUfoneb 7 X-Google-Smtp-Source: AGHT+IEv5k45Pnz4J20shFCzhfjwj9GpAntAKXrKttoCW2d3WclD2HmKoC699BkmgmHcg4HQHoePEw== X-Received: by 2002:a17:907:1b16:b0:ad8:914b:7d0b with SMTP id a640c23a62f3a-ae34fcf46ebmr326692766b.11.1751036964297; Fri, 27 Jun 2025 08:09:24 -0700 (PDT) Received: from 127.0.0.1localhost ([148.252.147.145]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae353c014fbsm135802866b.86.2025.06.27.08.09.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Jun 2025 08:09:23 -0700 (PDT) From: Pavel Begunkov To: io-uring@vger.kernel.org, linux-block@vger.kernel.org, linux-nvme@lists.infradead.org Cc: linux-fsdevel@vger.kernel.org, Keith Busch , David Wei , Vishal Verma , asml.silence@gmail.com Subject: [RFC 04/12] block: introduce dmavec bio type Date: Fri, 27 Jun 2025 16:10:31 +0100 Message-ID: <6b83e74f1840aab6a91d8e050acbfc408dd62c31.1751035820.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Premapped buffers don't require a generic bio_vec since these have already been dma mapped. Repurpose the bi_io_vec with the dma vector as they are mutually exclusive, and provide the setup and to support dma vectors. In order to use this, a driver must implement the .get_dma_device() blk-mq op. If the driver provides this callback, then it must be aware that any given bio may be using a dma_tag instead of a bio_vec. Note, splitting is not implemented just yet. Suggested-by: Keith Busch Signed-off-by: Pavel Begunkov --- block/bio.c | 21 +++++++++++++++++++++ block/blk-merge.c | 32 ++++++++++++++++++++++++++++++++ block/blk.h | 2 +- block/fops.c | 2 ++ include/linux/bio.h | 29 ++++++++++++++++++++++++++--- include/linux/blk_types.h | 6 +++++- 6 files changed, 87 insertions(+), 5 deletions(-) diff --git a/block/bio.c b/block/bio.c index 3c0a558c90f5..440f89b9e7de 100644 --- a/block/bio.c +++ b/block/bio.c @@ -838,6 +838,9 @@ static int __bio_clone(struct bio *bio, struct bio *bio_src, gfp_t gfp) bio_clone_blkg_association(bio, bio_src); } + if (bio_flagged(bio_src, BIO_DMAVEC)) + bio_set_flag(bio, BIO_DMAVEC); + if (bio_crypt_clone(bio, bio_src, gfp) < 0) return -ENOMEM; if (bio_integrity(bio_src) && @@ -1156,6 +1159,18 @@ void bio_iov_bvec_set(struct bio *bio, const struct iov_iter *iter) bio_set_flag(bio, BIO_CLONED); } +void bio_iov_dmavec_set(struct bio *bio, struct iov_iter *iter) +{ + WARN_ON_ONCE(bio->bi_max_vecs); + + bio->bi_vcnt = iter->nr_segs; + bio->bi_dmavec = (struct dmavec *)iter->dmavec; + bio->bi_iter.bi_bvec_done = iter->iov_offset; + bio->bi_iter.bi_size = iov_iter_count(iter); + bio->bi_opf |= REQ_NOMERGE; + bio_set_flag(bio, BIO_DMAVEC); +} + static unsigned int get_contig_folio_len(unsigned int *num_pages, struct page **pages, unsigned int i, struct folio *folio, size_t left, @@ -1322,6 +1337,10 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) bio_iov_bvec_set(bio, iter); iov_iter_advance(iter, bio->bi_iter.bi_size); return 0; + } else if (iov_iter_is_dma(iter)) { + bio_iov_dmavec_set(bio, iter); + iov_iter_advance(iter, bio->bi_iter.bi_size); + return 0; } if (iov_iter_extract_will_pin(iter)) @@ -1673,6 +1692,8 @@ struct bio *bio_split(struct bio *bio, int sectors, /* Zone append commands cannot be split */ if (WARN_ON_ONCE(bio_op(bio) == REQ_OP_ZONE_APPEND)) return ERR_PTR(-EINVAL); + if (WARN_ON_ONCE(bio_flagged(bio, BIO_DMAVEC))) + return ERR_PTR(-EINVAL); /* atomic writes cannot be split */ if (bio->bi_opf & REQ_ATOMIC) diff --git a/block/blk-merge.c b/block/blk-merge.c index 3af1d284add5..f932ed61dcb5 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -278,6 +278,35 @@ static unsigned int bio_split_alignment(struct bio *bio, return lim->logical_block_size; } +static int bio_split_rw_at_dmavec(struct bio *bio, const struct queue_limits *lim, + unsigned *segs, unsigned max_bytes) +{ + struct dmavec *dmav; + int offset, length; + + /* Aggressively refuse any splitting, should be improved */ + + if (!lim->virt_boundary_mask) + return -EINVAL; + if (bio->bi_vcnt > lim->max_segments) + return -EINVAL; + if (bio->bi_iter.bi_size > max_bytes) + return -EINVAL; + + dmav = &bio->bi_dmavec[bio->bi_iter.bi_idx]; + offset = bio->bi_iter.bi_bvec_done; + length = bio->bi_iter.bi_size; + while (length > 0) { + if (dmav->len - offset > lim->max_segment_size) + return -EINVAL; + length -= dmav->len; + dmav++; + } + *segs = bio->bi_vcnt; + return 0; +} + + /** * bio_split_rw_at - check if and where to split a read/write bio * @bio: [in] bio to be split @@ -297,6 +326,9 @@ int bio_split_rw_at(struct bio *bio, const struct queue_limits *lim, struct bvec_iter iter; unsigned nsegs = 0, bytes = 0; + if (bio_flagged(bio, BIO_DMAVEC)) + return bio_split_rw_at_dmavec(bio, lim, segs, max_bytes); + bio_for_each_bvec(bv, bio, iter) { /* * If the queue doesn't support SG gaps and adding this diff --git a/block/blk.h b/block/blk.h index 37ec459fe656..85429f542bd2 100644 --- a/block/blk.h +++ b/block/blk.h @@ -386,7 +386,7 @@ static inline struct bio *__bio_split_to_limits(struct bio *bio, switch (bio_op(bio)) { case REQ_OP_READ: case REQ_OP_WRITE: - if (bio_may_need_split(bio, lim)) + if (bio_may_need_split(bio, lim) || bio_flagged(bio, BIO_DMAVEC)) return bio_split_rw(bio, lim, nr_segs); *nr_segs = 1; return bio; diff --git a/block/fops.c b/block/fops.c index 1309861d4c2c..388acfe82b6c 100644 --- a/block/fops.c +++ b/block/fops.c @@ -347,6 +347,8 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb, * bio_iov_iter_get_pages() and set the bvec directly. */ bio_iov_bvec_set(bio, iter); + } else if (iov_iter_is_dma(iter)) { + bio_iov_dmavec_set(bio, iter); } else { ret = bio_iov_iter_get_pages(bio, iter); if (unlikely(ret)) diff --git a/include/linux/bio.h b/include/linux/bio.h index 8349569414ed..49f6b20d77f6 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -108,16 +108,36 @@ static inline bool bio_next_segment(const struct bio *bio, #define bio_for_each_segment_all(bvl, bio, iter) \ for (bvl = bvec_init_iter_all(&iter); bio_next_segment((bio), &iter); ) +static inline void bio_advance_iter_dma(const struct bio *bio, + struct bvec_iter *iter, unsigned int bytes) +{ + unsigned int idx = iter->bi_idx; + + iter->bi_size -= bytes; + bytes += iter->bi_bvec_done; + + while (bytes && bytes >= bio->bi_dmavec[idx].len) { + bytes -= bio->bi_dmavec[idx].len; + idx++; + } + + iter->bi_idx = idx; + iter->bi_bvec_done = bytes; +} + static inline void bio_advance_iter(const struct bio *bio, struct bvec_iter *iter, unsigned int bytes) { iter->bi_sector += bytes >> 9; - if (bio_no_advance_iter(bio)) + if (bio_no_advance_iter(bio)) { iter->bi_size -= bytes; - else + } else if (bio_flagged(bio, BIO_DMAVEC)) { + bio_advance_iter_dma(bio, iter, bytes); + } else { bvec_iter_advance(bio->bi_io_vec, iter, bytes); /* TODO: It is reasonable to complete bio with error here. */ + } } /* @bytes should be less or equal to bvec[i->bi_idx].bv_len */ @@ -129,6 +149,8 @@ static inline void bio_advance_iter_single(const struct bio *bio, if (bio_no_advance_iter(bio)) iter->bi_size -= bytes; + else if (bio_flagged(bio, BIO_DMAVEC)) + bio_advance_iter_dma(bio, iter, bytes); else bvec_iter_advance_single(bio->bi_io_vec, iter, bytes); } @@ -396,7 +418,7 @@ static inline void bio_wouldblock_error(struct bio *bio) */ static inline int bio_iov_vecs_to_alloc(struct iov_iter *iter, int max_segs) { - if (iov_iter_is_bvec(iter)) + if (iov_iter_is_bvec(iter) || iov_iter_is_dma(iter)) return 0; return iov_iter_npages(iter, max_segs); } @@ -443,6 +465,7 @@ int bdev_rw_virt(struct block_device *bdev, sector_t sector, void *data, int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter); void bio_iov_bvec_set(struct bio *bio, const struct iov_iter *iter); +void bio_iov_dmavec_set(struct bio *bio, struct iov_iter *iter); void __bio_release_pages(struct bio *bio, bool mark_dirty); extern void bio_set_pages_dirty(struct bio *bio); extern void bio_check_pages_dirty(struct bio *bio); diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index 3d1577f07c1c..dc2a5945604a 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -266,7 +266,10 @@ struct bio { atomic_t __bi_cnt; /* pin count */ - struct bio_vec *bi_io_vec; /* the actual vec list */ + union { + struct bio_vec *bi_io_vec; /* the actual vec list */ + struct dmavec *bi_dmavec; + }; struct bio_set *bi_pool; @@ -308,6 +311,7 @@ enum { BIO_REMAPPED, BIO_ZONE_WRITE_PLUGGING, /* bio handled through zone write plugging */ BIO_EMULATES_ZONE_APPEND, /* bio emulates a zone append operation */ + BIO_DMAVEC, /* Using premmaped dma buffers */ BIO_FLAG_LAST }; -- 2.49.0