From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6EE0AC43216 for ; Wed, 18 Aug 2021 16:17:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 54F70610A6 for ; Wed, 18 Aug 2021 16:17:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231280AbhHRQS0 (ORCPT ); Wed, 18 Aug 2021 12:18:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:43382 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229517AbhHRQSZ (ORCPT ); Wed, 18 Aug 2021 12:18:25 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8EDA6610A5; Wed, 18 Aug 2021 16:17:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629303470; bh=KPxieBci0vXg8rmYUy2so8SGtGACKhwfHUnpqQywB2U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YuZGxSb/qbJrnZ105zWsST1nzc3m5MixjmBIDb4Cqpf+Tw8XhntQlWVGRMwhIoXA7 PTtnTQEfAVvrGpcExRjt1ERSU8HOof1WS87z7lpzbE0XvNK4dmam1hUQ3Cb5tmEtl4 LQdsyFAHM06VRTXPscO6q5RGPRNYJ/p7auy1fidt0ulyrYV7J2rObWzPJh2wayByhW dD+K4DCpaPYtgRQUC0W7yQJz5RhyNsOdzq4PlthfwTFNMccSyBzUQf5XqVN5Xpf+0R eu2xlTZQILiBAamLWqT4orjL/dDPccR6l4KllQOYQis8vh+mMut2C5ziIwpIkHE3eK usfw3LYHare6w== Date: Wed, 18 Aug 2021 09:17:50 -0700 From: "Darrick J. Wong" To: Nitesh Shetty Cc: SelvaKumar S , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, linux-api@vger.kernel.org, linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, dm-devel@redhat.com, kbusch@kernel.org, axboe@kernel.dk, damien.lemoal@wdc.com, asml.silence@gmail.com, johannes.thumshirn@wdc.com, hch@lst.de, willy@infradead.org, kch@kernel.org, martin.petersen@oracle.com, mpatocka@redhat.com, bvanassche@acm.org, snitzer@redhat.com, agk@redhat.com, selvajove@gmail.com, joshiiitr@gmail.com, nj.shetty@samsung.com, joshi.k@samsung.com, javier.gonz@samsung.com Subject: Re: [PATCH 4/7] block: Introduce a new ioctl for simple copy Message-ID: <20210818161750.GF12664@magnolia> References: <20210817101423.12367-1-selvakuma.s1@samsung.com> <20210817101423.12367-5-selvakuma.s1@samsung.com> <20210817233613.GA12597@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Aug 18, 2021 at 09:07:54PM +0530, Nitesh Shetty wrote: > On Wed, Aug 18, 2021 at 5:06 AM Darrick J. Wong wrote: > > > > On Tue, Aug 17, 2021 at 03:44:20PM +0530, SelvaKumar S wrote: > > > From: Nitesh Shetty > > > > > > Add new BLKCOPY ioctl that offloads copying of one or more sources ranges > > > to a destination in the device. COPY ioctl accepts a 'copy_range' > > > structure that contains destination (in sectors), no of sources and > > > pointer to the array of source ranges. Each source range is represented by > > > 'range_entry' that contains start and length of source ranges (in sectors) > > > > > > MAX_COPY_NR_RANGE, limits the number of entries for the IOCTL and > > > MAX_COPY_TOTAL_LENGTH limits the total copy length, IOCTL can handle. > > > > > > Example code, to issue BLKCOPY: > > > /* Sample example to copy three source-ranges [0, 8] [16, 8] [32,8] to > > > * [64,24], on the same device */ > > > > > > int main(void) > > > { > > > int ret, fd; > > > struct range_entry source_range[] = {{.src = 0, .len = 8}, > > > {.src = 16, .len = 8}, {.src = 32, .len = 8},}; > > > struct copy_range cr; > > > > > > cr.dest = 64; > > > cr.nr_range = 3; > > > cr.range_list = (__u64)&source_range; > > > > > > fd = open("/dev/nvme0n1", O_RDWR); > > > if (fd < 0) return 1; > > > > > > ret = ioctl(fd, BLKCOPY, &cr); > > > if (ret < 0) printf("copy failure\n"); > > > > > > close(fd); > > > > > > return ret; > > > } > > > > > > Signed-off-by: Nitesh Shetty > > > Signed-off-by: SelvaKumar S > > > Signed-off-by: Kanchan Joshi > > > --- > > > block/ioctl.c | 33 +++++++++++++++++++++++++++++++++ > > > include/uapi/linux/fs.h | 8 ++++++++ > > > 2 files changed, 41 insertions(+) > > > > > > diff --git a/block/ioctl.c b/block/ioctl.c > > > index eb0491e90b9a..2af56d01e9fe 100644 > > > --- a/block/ioctl.c > > > +++ b/block/ioctl.c > > > @@ -143,6 +143,37 @@ static int blk_ioctl_discard(struct block_device *bdev, fmode_t mode, > > > GFP_KERNEL, flags); > > > } > > > > > > +static int blk_ioctl_copy(struct block_device *bdev, fmode_t mode, > > > + unsigned long arg) > > > +{ > > > + struct copy_range crange; > > > + struct range_entry *rlist; > > > + int ret; > > > + > > > + if (!(mode & FMODE_WRITE)) > > > + return -EBADF; > > > + > > > + if (copy_from_user(&crange, (void __user *)arg, sizeof(crange))) > > > + return -EFAULT; > > > + > > > + rlist = kmalloc_array(crange.nr_range, sizeof(*rlist), > > > + GFP_KERNEL); > > > + if (!rlist) > > > + return -ENOMEM; > > > + > > > + if (copy_from_user(rlist, (void __user *)crange.range_list, > > > + sizeof(*rlist) * crange.nr_range)) { > > > + ret = -EFAULT; > > > + goto out; > > > + } > > > + > > > + ret = blkdev_issue_copy(bdev, crange.nr_range, rlist, bdev, crange.dest, > > > + GFP_KERNEL, 0); > > > +out: > > > + kfree(rlist); > > > + return ret; > > > +} > > > + > > > static int blk_ioctl_zeroout(struct block_device *bdev, fmode_t mode, > > > unsigned long arg) > > > { > > > @@ -468,6 +499,8 @@ static int blkdev_common_ioctl(struct block_device *bdev, fmode_t mode, > > > case BLKSECDISCARD: > > > return blk_ioctl_discard(bdev, mode, arg, > > > BLKDEV_DISCARD_SECURE); > > > + case BLKCOPY: > > > + return blk_ioctl_copy(bdev, mode, arg); > > > case BLKZEROOUT: > > > return blk_ioctl_zeroout(bdev, mode, arg); > > > case BLKGETDISKSEQ: > > > diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h > > > index 7a97b588d892..4183688ff398 100644 > > > --- a/include/uapi/linux/fs.h > > > +++ b/include/uapi/linux/fs.h > > > @@ -76,6 +76,13 @@ struct range_entry { > > > __u64 len; > > > }; > > > > > > +struct copy_range { > > > + __u64 dest; > > > + __u64 nr_range; > > > > If the maximum number of elements in the range list is 1<<12, there's no > > need for this to be larger than a u16, right? > > > > > + __u64 range_list; > > > > Pointers embedded in a structure are /not/ a good idea, because this > > will create a lot of compatibility headaches for 32-bit binaries running > > on 64-bit kernels. Please just make the size of this header structure > > a multiple of 8 bytes and put the range_entry list immediately after it. > > > > struct copy_range { > > __s64 dest_offset; > > __u32 nr_range_entries; > > __u32 flags; > > __u64 reserved[2]; > > }; > > > > struct __user range_entry *re = ((struct range_entry *)(copyhead + 1)); > > > > copy_from_user(&urk, re...); > > > > --D > > > Thanks, this is better. 'Reserved' field was there to be used for > future extension of the interface. > Now that you mentioned 'flags', it seems we can do away with > 'reserved' fields altogether? We still want the reserved-must-be-zero fields so that adding the first field or two doesn't require changes to the pointer arithmetic. Also, I suppose you could make the relationship between copy_range and range_entry more explicit: struct copy_range { __s64 dest_offset; __u32 nr_range_entries; __u32 flags; __u64 reserved[2]; /* must come last */ struct range_entry entries[]; }; struct __user range_entry *re = ©head->entries[0]; --D > > Regards, > Nitesh Shetty