From: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
To: Max Reitz <mreitz@redhat.com>, qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-devel@nongnu.org
Subject: Re: [PATCH v7 41/47] block: Leave BDS.backing_file constant
Date: Mon, 27 Jul 2020 15:27:47 +0300 [thread overview]
Message-ID: <17ef88da-15fc-57ae-801e-a5374e87743f@virtuozzo.com> (raw)
In-Reply-To: <20200625152215.941773-42-mreitz@redhat.com>
On 25.06.2020 18:22, Max Reitz wrote:
> Parts of the block layer treat BDS.backing_file as if it were whatever
> the image header says (i.e., if it is a relative path, it is relative to
> the overlay), other parts treat it like a cache for
> bs->backing->bs->filename (relative paths are relative to the CWD).
> Considering bs->backing->bs->filename exists, let us make it mean the
> former.
>
> Among other things, this now allows the user to specify a base when
> using qemu-img to commit an image file in a directory that is not the
> CWD (assuming, everything uses relative filenames).
>
> Before this patch:
>
> $ ./qemu-img create -f qcow2 foo/bot.qcow2 1M
> $ ./qemu-img create -f qcow2 -b bot.qcow2 foo/mid.qcow2
> $ ./qemu-img create -f qcow2 -b mid.qcow2 foo/top.qcow2
> $ ./qemu-img commit -b mid.qcow2 foo/top.qcow2
> qemu-img: Did not find 'mid.qcow2' in the backing chain of 'foo/top.qcow2'
> $ ./qemu-img commit -b foo/mid.qcow2 foo/top.qcow2
> qemu-img: Did not find 'foo/mid.qcow2' in the backing chain of 'foo/top.qcow2'
> $ ./qemu-img commit -b $PWD/foo/mid.qcow2 foo/top.qcow2
> qemu-img: Did not find '[...]/foo/mid.qcow2' in the backing chain of 'foo/top.qcow2'
>
> After this patch:
>
> $ ./qemu-img commit -b mid.qcow2 foo/top.qcow2
> Image committed.
> $ ./qemu-img commit -b foo/mid.qcow2 foo/top.qcow2
> qemu-img: Did not find 'foo/mid.qcow2' in the backing chain of 'foo/top.qcow2'
> $ ./qemu-img commit -b $PWD/foo/mid.qcow2 foo/top.qcow2
> Image committed.
>
> With this change, bdrv_find_backing_image() must look at whether the
> user has overridden a BDS's backing file. If so, it can no longer use
> bs->backing_file, but must instead compare the given filename against
> the backing node's filename directly.
>
> Note that this changes the QAPI output for a node's backing_file. We
> had very inconsistent output there (sometimes what the image header
> said, sometimes the actual filename of the backing image). This
> inconsistent output was effectively useless, so we have to decide one
> way or the other. Considering that bs->backing_file usually at runtime
> contained the path to the image relative to qemu's CWD (or absolute),
> this patch changes QAPI's backing_file to always report the
> bs->backing->bs->filename from now on. If you want to receive the image
> header information, you have to refer to full-backing-filename.
>
> This necessitates a change to iotest 228. The interesting information
> it really wanted is the image header, and it can get that now, but it
> has to use full-backing-filename instead of backing_file. Because of
> this patch's changes to bs->backing_file's behavior, we also need some
> reference output changes.
>
> Along with the changes to bs->backing_file, stop updating
> BDS.backing_format in bdrv_backing_attach() as well. In order not to
> change our externally visible behavior (incompatibly), we have to let
> bdrv_query_image_info() try to get the image format from bs->backing if
> bs->backing_format is unset. (The QAPI schema describes
> backing-filename-format as "the format of the backing file", so it is
> not necessarily what the image header says, but just the format of the
> file referenced by backing-filename (if known).)
>
> iotest 245 changes in behavior: With the backing node no longer
> overriding the parent node's backing_file string, you can now omit the
> @backing option when reopening a node with neither a default nor a
> current backing file even if it used to have a backing node at some
> point.
>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
> include/block/block_int.h | 21 ++++++++++++++++-----
> block.c | 35 +++++++++++++++++++++++++++--------
> block/qapi.c | 17 +++++++++++++----
> tests/qemu-iotests/228 | 6 +++---
> tests/qemu-iotests/228.out | 6 +++---
> tests/qemu-iotests/245 | 4 +++-
> 6 files changed, 65 insertions(+), 24 deletions(-)
>
...
> diff --git a/block/qapi.c b/block/qapi.c
> index 2628323b63..5da6d7e6e0 100644
> --- a/block/qapi.c
> +++ b/block/qapi.c
> @@ -47,7 +47,7 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
> Error **errp)
> {
> ImageInfo **p_image_info;
> - BlockDriverState *bs0;
> + BlockDriverState *bs0, *backing;
> BlockDeviceInfo *info;
>
> if (!bs->drv) {
> @@ -76,9 +76,10 @@ BlockDeviceInfo *bdrv_block_device_info(BlockBackend *blk,
> info->node_name = g_strdup(bs->node_name);
> }
>
> - if (bs->backing_file[0]) {
> + backing = bdrv_cow_bs(bs);
> + if (backing) {
> info->has_backing_file = true;
> - info->backing_file = g_strdup(bs->backing_file);
> + info->backing_file = g_strdup(backing->filename);
> }
>
> if (!QLIST_EMPTY(&bs->dirty_bitmaps)) {
> @@ -314,6 +315,8 @@ void bdrv_query_image_info(BlockDriverState *bs,
> backing_filename = bs->backing_file;
> if (backing_filename[0] != '\0') {
> char *backing_filename2;
> + const char *backing_format = NULL;
> +
> info->backing_filename = g_strdup(backing_filename);
> info->has_backing_filename = true;
> backing_filename2 = bdrv_get_full_backing_filename(bs, NULL);
> @@ -326,7 +329,13 @@ void bdrv_query_image_info(BlockDriverState *bs,
> }
>
> if (bs->backing_format[0]) {
> - info->backing_filename_format = g_strdup(bs->backing_format);
> + backing_format = bs->backing_format;
> + } else if (bs->backing && bs->backing->bs->drv &&
> + !bdrv_backing_overridden(bs)) {
> + backing_format = bs->backing->bs->drv->format_name;
> + }
In case bdrv_backing_overridden() returns true , should we invoke
bdrv_refresh_filename() and assign the format_name then?
Andrey
> + if (backing_format) {
> + info->backing_filename_format = g_strdup(backing_format);
> info->has_backing_filename_format = true;
> }
> g_free(backing_filename2);
...
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
next prev parent reply other threads:[~2020-07-27 12:29 UTC|newest]
Thread overview: 173+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 15:21 [PATCH v7 00/47] block: Deal with filters Max Reitz
2020-06-25 15:21 ` [PATCH v7 01/47] block: Add child access functions Max Reitz
2020-07-08 17:22 ` Andrey Shinkevich
2020-07-13 9:06 ` Vladimir Sementsov-Ogievskiy
2020-07-16 14:46 ` Max Reitz
2020-07-28 16:09 ` Christophe de Dinechin
2020-08-07 9:33 ` Vladimir Sementsov-Ogievskiy
2020-07-13 9:57 ` Vladimir Sementsov-Ogievskiy
2020-06-25 15:21 ` [PATCH v7 02/47] block: Add chain helper functions Max Reitz
2020-07-08 17:20 ` Andrey Shinkevich
2020-07-09 8:24 ` Max Reitz
2020-07-09 9:07 ` Andrey Shinkevich
2020-07-13 10:18 ` Vladimir Sementsov-Ogievskiy
2020-07-16 14:50 ` Max Reitz
2020-07-16 15:24 ` Vladimir Sementsov-Ogievskiy
2020-06-25 15:21 ` [PATCH v7 03/47] block: bdrv_cow_child() for bdrv_has_zero_init() Max Reitz
2020-07-08 17:23 ` Andrey Shinkevich
2020-08-07 9:37 ` Vladimir Sementsov-Ogievskiy
2020-06-25 15:21 ` [PATCH v7 04/47] block: bdrv_set_backing_hd() is about bs->backing Max Reitz
2020-07-08 17:24 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 05/47] block: Include filters when freezing backing chain Max Reitz
2020-07-08 17:25 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 06/47] block: Drop bdrv_is_encrypted() Max Reitz
2020-07-08 17:41 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 07/47] block: Add bdrv_supports_compressed_writes() Max Reitz
2020-07-08 17:48 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 08/47] throttle: Support compressed writes Max Reitz
2020-07-08 17:52 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 09/47] copy-on-read: " Max Reitz
2020-07-08 17:54 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 10/47] mirror-top: " Max Reitz
2020-07-08 17:58 ` Andrey Shinkevich
2020-08-18 10:27 ` Kevin Wolf
2020-08-19 15:35 ` Max Reitz
2020-08-19 16:00 ` Kevin Wolf
2020-06-25 15:21 ` [PATCH v7 11/47] backup-top: " Max Reitz
2020-07-08 17:59 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 12/47] block: Use bdrv_filter_(bs|child) where obvious Max Reitz
2020-07-08 18:24 ` Andrey Shinkevich
2020-07-09 8:59 ` Max Reitz
2020-07-09 9:11 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 13/47] block: Use CAFs in block status functions Max Reitz
2020-07-08 19:13 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 14/47] stream: Deal with filters Max Reitz
2020-07-09 14:52 ` Andrey Shinkevich
2020-07-09 15:27 ` Andrey Shinkevich
2020-07-10 15:24 ` Max Reitz
2020-07-10 17:41 ` Andrey Shinkevich
2020-07-16 14:59 ` Max Reitz
2020-08-07 10:29 ` Vladimir Sementsov-Ogievskiy
2020-08-10 8:12 ` Max Reitz
2020-08-10 11:04 ` Vladimir Sementsov-Ogievskiy
2020-08-14 15:18 ` Andrey Shinkevich
2020-08-18 20:45 ` Andrey Shinkevich
2020-08-19 12:39 ` Max Reitz
2020-08-19 13:18 ` Vladimir Sementsov-Ogievskiy
2020-07-09 15:13 ` Andrey Shinkevich
2020-07-10 15:27 ` Max Reitz
2020-08-18 14:28 ` Kevin Wolf
2020-08-19 14:47 ` Max Reitz
2020-08-19 15:16 ` Kevin Wolf
2020-08-20 8:31 ` Max Reitz
2020-08-20 9:22 ` Max Reitz
2020-08-20 10:49 ` Vladimir Sementsov-Ogievskiy
2020-08-20 11:43 ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 15/47] block: Use CAFs when working with backing chains Max Reitz
2020-07-10 15:28 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 16/47] block: Use bdrv_cow_child() in bdrv_co_truncate() Max Reitz
2020-07-10 15:54 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 17/47] block: Re-evaluate backing file handling in reopen Max Reitz
2020-07-10 19:42 ` Andrey Shinkevich
2020-07-16 15:04 ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 18/47] block: Flush all children in generic code Max Reitz
2020-07-14 12:52 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 19/47] vmdk: Drop vmdk_co_flush() Max Reitz
2020-07-14 14:52 ` Andrey Shinkevich
2020-07-16 15:08 ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 20/47] block: Iterate over children in refresh_limits Max Reitz
2020-07-14 18:37 ` Andrey Shinkevich
2020-07-16 15:14 ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 21/47] block: Use CAFs in bdrv_refresh_filename() Max Reitz
2020-07-15 12:52 ` Andrey Shinkevich
2020-07-15 12:58 ` Andrey Shinkevich
2020-07-16 15:21 ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 22/47] block: Use CAF in bdrv_co_rw_vmstate() Max Reitz
2020-07-15 13:39 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 23/47] block/snapshot: Fix fallback Max Reitz
2020-07-15 21:22 ` Andrey Shinkevich
2020-07-15 22:18 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 24/47] block: Use CAFs for debug breakpoints Max Reitz
2020-07-15 21:43 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 25/47] block: Def. impl.s for get_allocated_file_size Max Reitz
2020-07-15 22:56 ` Andrey Shinkevich
2020-08-19 10:57 ` Kevin Wolf
2020-08-19 15:53 ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 26/47] block: Improve get_allocated_file_size's default Max Reitz
2020-07-20 15:12 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 27/47] blkverify: Use bdrv_sum_allocated_file_size() Max Reitz
2020-07-20 15:10 ` Andrey Shinkevich
2020-08-19 10:46 ` Kevin Wolf
2020-08-19 15:50 ` Max Reitz
2020-06-25 15:21 ` [PATCH v7 28/47] block/null: Implement bdrv_get_allocated_file_size Max Reitz
2020-07-20 15:10 ` Andrey Shinkevich
2020-07-24 8:58 ` Max Reitz
2020-07-24 9:49 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 29/47] blockdev: Use CAF in external_snapshot_prepare() Max Reitz
2020-07-20 16:08 ` Andrey Shinkevich
2020-07-24 9:23 ` Max Reitz
2020-07-24 10:37 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 30/47] block: Report data child for query-blockstats Max Reitz
2020-07-21 11:48 ` Andrey Shinkevich
2020-06-25 15:21 ` [PATCH v7 31/47] block: Use child access functions for QAPI queries Max Reitz
2020-07-21 12:30 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 32/47] block-copy: Use CAF to find sync=top base Max Reitz
2020-07-21 12:42 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 33/47] mirror: Deal with filters Max Reitz
2020-07-22 18:31 ` Andrey Shinkevich
2020-07-24 9:49 ` Max Reitz
2020-07-24 10:27 ` Andrey Shinkevich
2020-08-19 16:50 ` Kevin Wolf
2020-08-20 10:28 ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 34/47] backup: " Max Reitz
2020-07-23 15:51 ` Andrey Shinkevich
2020-07-24 9:55 ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 35/47] commit: " Max Reitz
2020-07-23 17:15 ` Andrey Shinkevich
2020-07-24 10:36 ` Andrey Shinkevich
2020-08-19 17:58 ` Kevin Wolf
2020-08-20 11:27 ` Max Reitz
2020-08-20 13:47 ` Kevin Wolf
2020-06-25 15:22 ` [PATCH v7 36/47] nbd: Use CAF when looking for dirty bitmap Max Reitz
2020-07-23 17:21 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 37/47] qemu-img: Use child access functions Max Reitz
2020-07-24 15:51 ` Andrey Shinkevich
2020-08-21 15:29 ` Kevin Wolf
2020-08-24 12:42 ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 38/47] block: Drop backing_bs() Max Reitz
2020-07-24 15:55 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 39/47] blockdev: Fix active commit choice Max Reitz
2020-08-21 15:50 ` Kevin Wolf
2020-08-24 13:18 ` Max Reitz
2020-08-24 14:07 ` Kevin Wolf
2020-08-24 14:41 ` Max Reitz
2020-08-24 15:06 ` Kevin Wolf
2020-06-25 15:22 ` [PATCH v7 40/47] block: Inline bdrv_co_block_status_from_*() Max Reitz
2020-07-24 18:00 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 41/47] block: Leave BDS.backing_file constant Max Reitz
2020-07-27 12:27 ` Andrey Shinkevich [this message]
2020-07-28 14:10 ` Max Reitz
2020-08-24 13:14 ` Kevin Wolf
2020-08-24 14:29 ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 42/47] iotests: Test that qcow2's data-file is flushed Max Reitz
2020-07-27 13:28 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 43/47] iotests: Let complete_and_wait() work with commit Max Reitz
2020-07-27 13:35 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 44/47] iotests: Add filter commit test cases Max Reitz
2020-07-27 17:45 ` Andrey Shinkevich
2020-07-28 14:00 ` Max Reitz
2020-06-25 15:22 ` [PATCH v7 45/47] iotests: Add filter mirror " Max Reitz
2020-08-02 11:05 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 46/47] iotests: Add test for commit in sub directory Max Reitz
2020-08-02 12:13 ` Andrey Shinkevich
2020-06-25 15:22 ` [PATCH v7 47/47] iotests: Test committing to overridden backing Max Reitz
2020-08-02 11:43 ` Andrey Shinkevich
2020-07-08 17:20 ` [PATCH v7 00/47] block: Deal with filters Andrey Shinkevich
2020-07-08 17:32 ` Eric Blake
2020-07-08 19:46 ` Andrey Shinkevich
2020-07-08 20:37 ` Eric Blake
2020-07-09 8:19 ` Max Reitz
2020-07-08 20:47 ` Eric Blake
2020-07-09 8:20 ` Max Reitz
2020-07-09 9:04 ` Andrey Shinkevich
2020-08-24 15:15 ` Kevin Wolf
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