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block: Support BDRV_REQ_WRITE_UNCHANGED in filters 

Update the rest of the filter drivers to support
BDRV_REQ_WRITE_UNCHANGED.  They already forward write request flags to
their children, so we just have to announce support for it.

This patch does not cover the replication driver because that currently
does not support flags at all, and because it just grabs the WRITE
permission for its children when it can, so we should be fine just
submitting the incoming WRITE_UNCHANGED requests as normal writes.

It also does not cover format drivers for similar reasons.  They all use
bdrv_format_default_perms() as their .bdrv_child_perm() implementation
so they just always grab the WRITE permission for their file children
whenever possible.  In addition, it often would be difficult to
ascertain whether incoming unchanging writes end up as unchanging writes
in their files.  So we just leave them as normal potentially changing
writes.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-7-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2018-04-21 15:29:26 +02:00
parent 1b1a920b71
commit 228345bf5d
7 changed files with 28 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
block/blkdebug.c
View File

@ -398,10 +398,11 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
goto out;
}
bs->supported_write_flags = BDRV_REQ_FUA &
bs->file->bs->supported_write_flags;
bs->supported_zero_flags = (BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &
bs->file->bs->supported_zero_flags;
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
(BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &
bs->file->bs->supported_zero_flags);
ret = -EINVAL;
/* Set alignment overrides */

3
block/blkreplay.c
View File

@ -35,6 +35,9 @@ static int blkreplay_open(BlockDriverState *bs, QDict *options, int flags,
goto fail;
}
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;
ret = 0;
fail:
return ret;

3
block/blkverify.c
View File

@ -141,6 +141,9 @@ static int blkverify_open(BlockDriverState *bs, QDict *options, int flags,
goto fail;
}
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;
ret = 0;
fail:
qemu_opts_del(opts);

10
block/copy-on-read.c
View File

@ -33,11 +33,13 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags,
return -EINVAL;
}
bs->supported_write_flags = BDRV_REQ_FUA &
bs->file->bs->supported_write_flags;
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
(BDRV_REQ_FUA &
bs->file->bs->supported_write_flags);
bs->supported_zero_flags = (BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &
bs->file->bs->supported_zero_flags;
bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &
bs->file->bs->supported_zero_flags);
return 0;
}

2
block/mirror.c
View File

@ -1134,6 +1134,8 @@ static void mirror_start_job(const char *job_id, BlockDriverState *bs,
mirror_top_bs->implicit = true;
}
mirror_top_bs->total_sectors = bs->total_sectors;
mirror_top_bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
mirror_top_bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;
bdrv_set_aio_context(mirror_top_bs, bdrv_get_aio_context(bs));
/* bdrv_append takes ownership of the mirror_top_bs reference, need to keep

9
block/raw-format.c
View File

@ -415,10 +415,11 @@ static int raw_open(BlockDriverState *bs, QDict *options, int flags,
}
bs->sg = bs->file->bs->sg;
bs->supported_write_flags = BDRV_REQ_FUA &
bs->file->bs->supported_write_flags;
bs->supported_zero_flags = (BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &
bs->file->bs->supported_zero_flags;
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
(BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &
bs->file->bs->supported_zero_flags);
if (bs->probed && !bdrv_is_read_only(bs)) {
fprintf(stderr,

6
block/throttle.c
View File

@ -81,8 +81,10 @@ static int throttle_open(BlockDriverState *bs, QDict *options,
if (!bs->file) {
return -EINVAL;
}
bs->supported_write_flags = bs->file->bs->supported_write_flags;
bs->supported_zero_flags = bs->file->bs->supported_zero_flags;
bs->supported_write_flags = bs->file->bs->supported_write_flags |
BDRV_REQ_WRITE_UNCHANGED;
bs->supported_zero_flags = bs->file->bs->supported_zero_flags |
BDRV_REQ_WRITE_UNCHANGED;
return throttle_configure_tgm(bs, tgm, options, errp);
}