From e1c66c6d82fe5988d66531febc27ef8480c44c8a Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Wed, 21 Aug 2013 12:41:17 +0200 Subject: [PATCH] add skeleton for BSD licensed "raw" BlockDriver On 08/05/13 15:03, Paolo Bonzini wrote: > > > ----- Original Message ----- >> From: "Laszlo Ersek" >> To: "Paolo Bonzini" >> Sent: Monday, August 5, 2013 2:43:46 PM >> Subject: Re: [PATCH 1/2] raw: add license header >> >> On 08/02/13 00:27, Paolo Bonzini wrote: >>> On 08/01/2013 10:13 AM, Christoph Hellwig wrote: >>>> On Wed, Jul 31, 2013 at 08:19:51AM +0200, Paolo Bonzini wrote: >>>>> Most of the block layer is under the BSD license, thus it is >>>>> reasonable to license block/raw.c the same way. CCed people should >>>>> ACK by replying with a Signed-off-by line. >>>> >>>> The coded was intended to be GPLv2. >>> >>> Laszlo, would you be willing to do clean-room reverse engineering? >>> >>> (No rants, please. :)) >> >> What's the scope exactly? > > It's quite small, it's a file full of forwarders like > > static void raw_foo(BlockDriverState *bs) > { > return bdrv_foo(bs->file); > } > > It's 170 lines of code, all as boring as this. I only picked you > because I'm quite certain you have never seen the file (and the answer > confirmed it). > > Basically: > > 1) BlockDriver is a struct in which these function members are > interesting: > > .bdrv_reopen_prepare > .bdrv_co_readv > .bdrv_co_writev > .bdrv_co_is_allocated > .bdrv_co_write_zeroes > .bdrv_co_discard > .bdrv_getlength > .bdrv_get_info > .bdrv_truncate > .bdrv_is_inserted > .bdrv_media_changed > .bdrv_eject > .bdrv_lock_medium > .bdrv_ioctl > .bdrv_aio_ioctl > .bdrv_has_zero_init > > They should be implemented as simple forwarders (see above). > There are 16 functions listed here, you can easily see how this > already accounts for 100+ SLOC roughly... > > The implementations of bdrv_co_readv and bdrv_co_writev should also > call BLKDBG_EVENT on bs->file too, before forwarding to bs->file. The > events to be generated are BLKDBG_READ_AIO and BLKDBG_WRITE_AIO. > > 2) This is also a simple forwarder function: > > .bdrv_create > > but there is no BlockDriverState argument so the forwarded-to function > does not have a bs->file argument either. The forwarded-to function > is bdrv_create_file. > > 3) These members are special > > .format_name is the string "raw" > .bdrv_open raw_open should set bs->sg to bs->file->sg and return 0 > .bdrv_close raw_close should do nothing > .bdrv_probe raw_probe should just return 1. > > 4) There is another member, .create_options, which is an array of > QEMUOptionParameter structs, terminated by an all-zero item. The only > option you need is for the virtual disk size. You will find something > to copy from in other block drivers, for example block/qcow2.c. > > 5) Formats are registered with bdrv_register (takes a BlockDriver*). > You also need to pass the caller of bdrv_register to block_init. > > 6) I'm not sure how to organize the patch series, so I'll leave this to > your creativity. I guess in this case move/copy detection of git should > be disabled. I would definitely include this spec in the commit > message as a proof of clean-room reverse engineering. > > 7) Remember a BSD header like the one in block.c. > > Paolo This patch implements the email up to the paragraph ending with "100+ SLOC roughly". The skeleton is generated from the list there, with a simple shell loop using "sed" and the raw_foo() template. The BSD license block is copied (and reflowed) from "util/qemu-progress.c". Signed-off-by: Laszlo Ersek Signed-off-by: Kevin Wolf --- block/raw_bsd.c | 108 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 block/raw_bsd.c diff --git a/block/raw_bsd.c b/block/raw_bsd.c new file mode 100644 index 0000000000..5c17d538e5 --- /dev/null +++ b/block/raw_bsd.c @@ -0,0 +1,108 @@ +/* BlockDriver implementation for "raw" + * + * Copyright (C) 2013, Red Hat, Inc. + * + * Author: + * Laszlo Ersek + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to + * deal in the Software without restriction, including without limitation the + * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or + * sell copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + */ + +#include "block/block_int.h" + +static TYPE raw_reopen_prepare(BlockDriverState *bs) +{ + return bdrv_reopen_prepare(bs->file); +} + +static TYPE raw_co_readv(BlockDriverState *bs) +{ + return bdrv_co_readv(bs->file); +} + +static TYPE raw_co_writev(BlockDriverState *bs) +{ + return bdrv_co_writev(bs->file); +} + +static TYPE raw_co_is_allocated(BlockDriverState *bs) +{ + return bdrv_co_is_allocated(bs->file); +} + +static TYPE raw_co_write_zeroes(BlockDriverState *bs) +{ + return bdrv_co_write_zeroes(bs->file); +} + +static TYPE raw_co_discard(BlockDriverState *bs) +{ + return bdrv_co_discard(bs->file); +} + +static TYPE raw_getlength(BlockDriverState *bs) +{ + return bdrv_getlength(bs->file); +} + +static TYPE raw_get_info(BlockDriverState *bs) +{ + return bdrv_get_info(bs->file); +} + +static TYPE raw_truncate(BlockDriverState *bs) +{ + return bdrv_truncate(bs->file); +} + +static TYPE raw_is_inserted(BlockDriverState *bs) +{ + return bdrv_is_inserted(bs->file); +} + +static TYPE raw_media_changed(BlockDriverState *bs) +{ + return bdrv_media_changed(bs->file); +} + +static TYPE raw_eject(BlockDriverState *bs) +{ + return bdrv_eject(bs->file); +} + +static TYPE raw_lock_medium(BlockDriverState *bs) +{ + return bdrv_lock_medium(bs->file); +} + +static TYPE raw_ioctl(BlockDriverState *bs) +{ + return bdrv_ioctl(bs->file); +} + +static TYPE raw_aio_ioctl(BlockDriverState *bs) +{ + return bdrv_aio_ioctl(bs->file); +} + +static TYPE raw_has_zero_init(BlockDriverState *bs) +{ + return bdrv_has_zero_init(bs->file); +} +