izzy/xemu
0
0
Fork 0
mirror of https://github.com/izzy2lost/xemu.git synced 2026-07-06 00:20:22 -07:00
Code Issues Packages Projects Releases Wiki Activity

block: allow commit to unmap zero blocks

Browse Source 
Non-active block commits do not discard blocks only containing zeros,
causing images to lose sparseness after the commit. This commit fixes
that by writing zero blocks using blk_co_pwrite_zeroes rather than
writing them out as any other arbitrary data.

Signed-off-by: Vincent Vanlaer <libvirt-e6954efa@volkihar.be>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-Id: <20241026163010.2865002-5-libvirt-e6954efa@volkihar.be>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
This commit is contained in:
Vincent Vanlaer
2025-05-01 12:12:19 +03:00
committed by Vladimir Sementsov-Ogievskiy
parent 0648c76ad1
commit 6f3199f996
1 changed files with 29 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files
block/commit.c
+29 -9
View File
@@ -150,19 +150,39 @@ static int commit_iteration(CommitBlockJob *s, int64_t offset,
}
if (ret & BDRV_BLOCK_ALLOCATED) {
assert(bytes < SIZE_MAX);
if (ret & BDRV_BLOCK_ZERO) {
/*
* If the top (sub)clusters are smaller than the base
* (sub)clusters, this will not unmap unless the underlying device
* does some tracking of these requests. Ideally, we would find
* the maximal extent of the zero clusters.
*/
ret = blk_co_pwrite_zeroes(s->base, offset, bytes,
BDRV_REQ_MAY_UNMAP);
if (ret < 0) {
error_in_source = false;
goto fail;
}
} else {
assert(bytes < SIZE_MAX);
ret = blk_co_pread(s->top, offset, bytes, buf, 0);
if (ret < 0) {
goto fail;
}
ret = blk_co_pread(s->top, offset, bytes, buf, 0);
if (ret < 0) {
goto fail;
}
ret = blk_co_pwrite(s->base, offset, bytes, buf, 0);
if (ret < 0) {
error_in_source = false;
goto fail;
ret = blk_co_pwrite(s->base, offset, bytes, buf, 0);
if (ret < 0) {
error_in_source = false;
goto fail;
}
}
/*
* Whether zeroes actually end up on disk depends on the details of
* the underlying driver. Therefore, this might rate limit more than
* is necessary.
*/
block_job_ratelimit_processed_bytes(&s->common, bytes);
}