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[Qemu-block] [PATCH v5] qemu-img: check block status of backing file whe
From: |
Ren Kimura |
Subject: |
[Qemu-block] [PATCH v5] qemu-img: check block status of backing file when converting. |
Date: |
Thu, 28 Apr 2016 01:04:58 +0900 |
When converting images, check the block status of its backing file chain
to avoid needlessly reading zeros.
Signed-off-by: Ren Kimura <address@hidden>
---
qemu-img.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/qemu-img.c b/qemu-img.c
index 1697762..cb72f14 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1478,10 +1478,21 @@ 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;
}
--
2.5.0
- [Qemu-block] [PATCH v5] qemu-img: check block status of backing file when converting.,
Ren Kimura <=