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[PULL 04/27] qemu-img: add chunk size parameter to compare_buffers()
From: |
Kevin Wolf |
Subject: |
[PULL 04/27] qemu-img: add chunk size parameter to compare_buffers() |
Date: |
Tue, 31 Oct 2023 19:58:55 +0100 |
From: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Add @chsize param to the function which, if non-zero, would represent
the chunk size to be used for comparison. If it's zero, then
BDRV_SECTOR_SIZE is used as default chunk size, which is the previous
behaviour.
In particular, we're going to use this param in img_rebase() to make the
write requests aligned to a predefined alignment value.
Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Czenczek <hreitz@redhat.com>
Message-ID: <20230919165804.439110-5-andrey.drobyshev@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
qemu-img.c | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
diff --git a/qemu-img.c b/qemu-img.c
index e61d996e0f..a64a664a37 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1274,23 +1274,29 @@ static int is_allocated_sectors_min(const uint8_t *buf,
int n, int *pnum,
}
/*
- * Compares two buffers sector by sector. Returns 0 if the first
- * sector of each buffer matches, non-zero otherwise.
+ * Compares two buffers chunk by chunk, where @chsize is the chunk size.
+ * If @chsize is 0, default chunk size of BDRV_SECTOR_SIZE is used.
+ * Returns 0 if the first chunk of each buffer matches, non-zero otherwise.
*
- * pnum is set to the sector-aligned size of the buffer prefix that
- * has the same matching status as the first sector.
+ * @pnum is set to the size of the buffer prefix aligned to @chsize that
+ * has the same matching status as the first chunk.
*/
static int compare_buffers(const uint8_t *buf1, const uint8_t *buf2,
- int64_t bytes, int64_t *pnum)
+ int64_t bytes, uint64_t chsize, int64_t *pnum)
{
bool res;
- int64_t i = MIN(bytes, BDRV_SECTOR_SIZE);
+ int64_t i;
assert(bytes > 0);
+ if (!chsize) {
+ chsize = BDRV_SECTOR_SIZE;
+ }
+ i = MIN(bytes, chsize);
+
res = !!memcmp(buf1, buf2, i);
while (i < bytes) {
- int64_t len = MIN(bytes - i, BDRV_SECTOR_SIZE);
+ int64_t len = MIN(bytes - i, chsize);
if (!!memcmp(buf1 + i, buf2 + i, len) != res) {
break;
@@ -1559,7 +1565,7 @@ static int img_compare(int argc, char **argv)
ret = 4;
goto out;
}
- ret = compare_buffers(buf1, buf2, chunk, &pnum);
+ ret = compare_buffers(buf1, buf2, chunk, 0, &pnum);
if (ret || pnum != chunk) {
qprintf(quiet, "Content mismatch at offset %" PRId64 "!\n",
offset + (ret ? 0 : pnum));
@@ -3887,7 +3893,7 @@ static int img_rebase(int argc, char **argv)
int64_t pnum;
if (compare_buffers(buf_old + written, buf_new + written,
- n - written, &pnum))
+ n - written, 0, &pnum))
{
if (buf_old_is_zero) {
ret = blk_pwrite_zeroes(blk, offset + written, pnum,
0);
--
2.41.0
- [PULL 00/27] Block layer patches, Kevin Wolf, 2023/10/31
- [PULL 01/27] qemu-img: rebase: stop when reaching EOF of old backing file, Kevin Wolf, 2023/10/31
- [PULL 02/27] qemu-iotests: 024: add rebasing test case for overlay_size > backing_size, Kevin Wolf, 2023/10/31
- [PULL 03/27] qemu-img: rebase: use backing files' BlockBackend for buffer alignment, Kevin Wolf, 2023/10/31
- [PULL 04/27] qemu-img: add chunk size parameter to compare_buffers(),
Kevin Wolf <=
- [PULL 07/27] qemu-img: add compression option to rebase subcommand, Kevin Wolf, 2023/10/31
- [PULL 05/27] qemu-img: rebase: avoid unnecessary COW operations, Kevin Wolf, 2023/10/31
- [PULL 06/27] iotests/{024, 271}: add testcases for qemu-img rebase, Kevin Wolf, 2023/10/31
- [PULL 16/27] virtio: use defer_call() in virtio_irqfd_notify(), Kevin Wolf, 2023/10/31
- [PULL 15/27] util/defer-call: move defer_call() to util/, Kevin Wolf, 2023/10/31
- [PULL 21/27] block/mirror: determine copy_to_target only once, Kevin Wolf, 2023/10/31
- [PULL 19/27] block/mirror: set actively_synced even after the job is ready, Kevin Wolf, 2023/10/31
- [PULL 20/27] block/mirror: move dirty bitmap to filter, Kevin Wolf, 2023/10/31
- [PULL 17/27] virtio-blk: remove batch notification BH, Kevin Wolf, 2023/10/31
- [PULL 13/27] blockdev: mirror: avoid potential deadlock when using iothread, Kevin Wolf, 2023/10/31