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[Qemu-devel] [PATCH] vpc: Implement bdrv_co_get_status()
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH] vpc: Implement bdrv_co_get_status() |
Date: |
Wed, 11 Feb 2015 17:23:08 +0100 |
This implements bdrv_co_get_status() for VHD images. This can
significantly speed up qemu-img convert operation because only with this
function implemented sparseness can be considered. (Before, converting a
1 TB empty image took several minutes for me, now it's instantaneous.)
Signed-off-by: Kevin Wolf <address@hidden>
---
block/vpc.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 52 insertions(+), 2 deletions(-)
diff --git a/block/vpc.c b/block/vpc.c
index 46803b1..379ff4a 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -597,6 +597,55 @@ static coroutine_fn int vpc_co_write(BlockDriverState *bs,
int64_t sector_num,
return ret;
}
+static int64_t coroutine_fn vpc_co_get_block_status(BlockDriverState *bs,
+ int64_t sector_num, int nb_sectors, int *pnum)
+{
+ BDRVVPCState *s = bs->opaque;
+ VHDFooter *footer = (VHDFooter *) s->footer_buf;
+ int64_t start, offset;
+ bool allocated;
+ int n;
+
+ if (be32_to_cpu(footer->type) == VHD_FIXED) {
+ *pnum = nb_sectors;
+ return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | BDRV_BLOCK_DATA |
+ (sector_num << BDRV_SECTOR_BITS);
+ }
+
+ offset = get_sector_offset(bs, sector_num, 0);
+
+ *pnum = 1;
+ start = offset;
+ allocated = (offset != -1);
+ nb_sectors--;
+
+ while (nb_sectors > 0) {
+ offset = get_sector_offset(bs, sector_num, 0);
+
+ if ((offset != -1) != allocated) {
+ break;
+ }
+
+ if (allocated && offset != start + (*pnum * 512)) {
+ break;
+ }
+
+ /* All sectors in a block are contiguous (without using the bitmap) */
+ n = ROUND_UP(sector_num + 1, s->block_size / 512) - sector_num;
+ n = MIN(n, nb_sectors);
+
+ *pnum += n;
+ sector_num += n;
+ nb_sectors -= n;
+ }
+
+ if (allocated) {
+ return BDRV_BLOCK_DATA | BDRV_BLOCK_OFFSET_VALID | start;
+ } else {
+ return 0;
+ }
+}
+
/*
* Calculates the number of cylinders, heads and sectors per cylinder
* based on a given number of sectors. This is the algorithm described
@@ -907,8 +956,9 @@ static BlockDriver bdrv_vpc = {
.bdrv_reopen_prepare = vpc_reopen_prepare,
.bdrv_create = vpc_create,
- .bdrv_read = vpc_co_read,
- .bdrv_write = vpc_co_write,
+ .bdrv_read = vpc_co_read,
+ .bdrv_write = vpc_co_write,
+ .bdrv_co_get_block_status = vpc_co_get_block_status,
.bdrv_get_info = vpc_get_info,
--
1.8.3.1
- [Qemu-devel] [PATCH] vpc: Implement bdrv_co_get_status(),
Kevin Wolf <=