Re: [Qemu-devel] [Qemu-block] [PULL 76/76] block: move I/O request processing to block/io.c

[Eric Blake <eblake@redhat.com>]

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On 04/28/2015 09:00 AM, Kevin Wolf wrote:
> From: Stefan Hajnoczi <stefanha@redhat.com>
> 
> The block.c file has grown to over 6000 lines.  It is time to split this
> file so there are fewer conflicts and the code is easier to maintain.
> 
> Extract I/O request processing code:
>  * Read
>  * Write
>  * Zero writes and making the image empty
>  * Flush
>  * Discard
>  * ioctl
>  * Tracked requests and queuing
>  * Throttling and copy-on-read
>  * Block status and allocated functions
>  * Refreshing block limits
>  * Reading/writing vmstate
>  * qemu_blockalign() and friends
> 
> The patch simply moves code from block.c into block/io.c.
> 
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  block.c             | 3394 +++++++--------------------------------------------
>  block/Makefile.objs |    2 +-
>  block/io.c          | 2540 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 2982 insertions(+), 2954 deletions(-)
>  create mode 100644 block/io.c

Kevin, compare your diff to Stefan's:

> ---
>  block.c             | 2512 --------------------------------------------------
>  block/Makefile.objs |    2 +-
>  block/io.c          | 2540 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 2541 insertions(+), 2513 deletions(-)
>  create mode 100644 block/io.c

The difference is that Stefan has done 'git config diff.algorithm
patience', which makes for MUCH more legible diffs on a code motion
patch.  http://wiki.qemu.org/Contribute/SubmitAPatch mentions this as a
hint for a nicer setup.

At any rate, you've already sent the pull request, so I'm probably too
late; but for the record, here's why I would add:
Reviewed-by: Eric Blake <eblake@redhat.com>
when reviewing Stefan's version of the patch (the two versions give the
same end result, but my review technique falls flat on Kevin's replay of
the patch)

$ diff -u <(sed -n 's/^-//p' patch) <(sed -n 's/^+//p' patch)
--- /dev/fd/63	2015-04-28 11:13:24.696901797 -0600
+++ /dev/fd/62	2015-04-28 11:13:24.697901792 -0600
@@ -1,6 +1,38 @@
---
--- a/block.c
+++ b/block.c
+++ b/block/Makefile.objs
+block-obj-y += null.o mirror.o io.o
+++ b/block/io.c
+/*
+ * Block layer I/O functions
+ *
+ * Copyright (c) 2003 Fabrice Bellard
+ *
+ * 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 "trace.h"
 #include "sysemu/qtest.h"
+#include "block/blockjob.h"
+#include "block/block_int.h"
+
+#define NOT_DONE 0x7fffffff /* used while emulated sync operation in
progress */
+
 static BlockAIOCB *bdrv_aio_readv_em(BlockDriverState *bs,
         int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
         BlockCompletionFunc *cb, void *opaque);
@@ -465,7 +497,6 @@
     return waited;
 }

-
 static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
                                    size_t size)
 {
@@ -2511,8 +2542,3 @@
         bdrv_flush_io_queue(bs->file);
     }
 }
-
--- a/block/Makefile.objs
-block-obj-y += null.o mirror.o
--- /dev/null
-- 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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