system/qemu
system/qemu
1
0
Fork 0
mirror of https://gitlab.com/qemu-project/qemu synced 2024-11-05 20:35:44 +00:00
Code Issues Projects Releases Packages Wiki Activity

qemu-img: check block status of backing file when converting.

Browse source 
When converting images, check the block status of its backing file chain
to avoid needlessly reading zeros.

Signed-off-by: Ren Kimura <rkx1209dev@gmail.com>
Message-id: 1461773098-20356-1-git-send-email-rkx1209dev@gmail.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Ren Kimura 2016-04-28 01:04:58 +09:00 committed by Max Reitz
parent 9036e87c74
commit 263a6f4c3a
1 changed files with 13 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

15
qemu-img.c
View file

@ -1475,10 +1475,21 @@ static int convert_iteration_sectors(ImgConvertState *s, int64_t sector_num)
} else if (!s->target_has_backing) {
/* Without a target backing file we must copy over the contents of
* the backing file as well. */
/* TODO Check block status of the backing file chain to avoid
/* Check block status of the backing file chain to avoid
* needlessly reading zeroes and limiting the iteration to the
* buffer size */
s->status = BLK_DATA;
ret = bdrv_get_block_status_above(blk_bs(s->src[s->src_cur]), NULL,
sector_num - s->src_cur_offset,
n, &n, &file);
if (ret < 0) {
return ret;
}
if (ret & BDRV_BLOCK_ZERO) {
s->status = BLK_ZERO;
} else {
s->status = BLK_DATA;
}
} else {
s->status = BLK_BACKING_FILE;
}