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[Qemu-devel] [RFC][PATCH] qemu-img: add support for skipping zeroes in i
From: |
Peter Lieven |
Subject: |
[Qemu-devel] [RFC][PATCH] qemu-img: add support for skipping zeroes in input during convert |
Date: |
Fri, 22 Nov 2013 15:48:30 +0100 |
Signed-off-by: Peter Lieven <address@hidden>
---
qemu-img.c | 52 ++++++++++++++++++++++++++++++----------------------
1 file changed, 30 insertions(+), 22 deletions(-)
diff --git a/qemu-img.c b/qemu-img.c
index b6b5644..808f8f8 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1121,8 +1121,9 @@ out3:
static int img_convert(int argc, char **argv)
{
- int c, ret = 0, n, n1, bs_n, bs_i, compress, cluster_size,
+ int c, n, n1, bs_n, bs_i, compress, cluster_size,
cluster_sectors, skip_create;
+ int64_t ret = 0;
int progress = 0, flags;
const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename;
BlockDriver *drv, *proto_drv;
@@ -1479,11 +1480,6 @@ static int img_convert(int argc, char **argv)
if (nb_sectors <= 0) {
break;
}
- if (nb_sectors >= (IO_BUF_SIZE / 512)) {
- n = (IO_BUF_SIZE / 512);
- } else {
- n = nb_sectors;
- }
while (sector_num - bs_offset >= bs_sectors) {
bs_i ++;
@@ -1495,34 +1491,46 @@ static int img_convert(int argc, char **argv)
sector_num, bs_i, bs_offset, bs_sectors); */
}
- if (n > bs_offset + bs_sectors - sector_num) {
- n = bs_offset + bs_sectors - sector_num;
- }
-
- /* If the output image is being created as a copy on write image,
- assume that sectors which are unallocated in the input image
- are present in both the output's and input's base images (no
- need to copy them). */
- if (out_baseimg) {
- ret = bdrv_is_allocated(bs[bs_i], sector_num - bs_offset,
- n, &n1);
+ if (out_baseimg || has_zero_init) {
+ n = nb_sectors > INT_MAX ? INT_MAX : nb_sectors;
+ ret = bdrv_get_block_status(bs[bs_i], sector_num - bs_offset,
+ n, &n1);
if (ret < 0) {
- error_report("error while reading metadata for sector "
- "%" PRId64 ": %s",
+ error_report("error while reading block status of sector
%" PRId64 ": %s",
sector_num - bs_offset, strerror(-ret));
goto out;
}
- if (!ret) {
+ /* If the output image is zero initialized, we are not working
+ * on a shared base and the input is zero we can skip the next
+ * n1 bytes */
+ if (!out_baseimg && has_zero_init && ret & BDRV_BLOCK_ZERO) {
+ sector_num += n1;
+ continue;
+ }
+ /* If the output image is being created as a copy on write
image,
+ assume that sectors which are unallocated in the input image
+ are present in both the output's and input's base images (no
+ need to copy them). */
+ if (out_baseimg && !(ret & BDRV_BLOCK_DATA)) {
sector_num += n1;
continue;
}
/* The next 'n1' sectors are allocated in the input image. Copy
only those as they may be followed by unallocated sectors.
*/
- n = n1;
+ nb_sectors = n1;
+ }
+
+ if (nb_sectors >= (IO_BUF_SIZE / 512)) {
+ n = (IO_BUF_SIZE / 512);
} else {
- n1 = n;
+ n = nb_sectors;
+ }
+
+ if (n > bs_offset + bs_sectors - sector_num) {
+ n = bs_offset + bs_sectors - sector_num;
}
+ n1 = n;
ret = bdrv_read(bs[bs_i], sector_num - bs_offset, buf, n);
if (ret < 0) {
error_report("error while reading sector %" PRId64 ": %s",
--
1.7.9.5
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