| Message ID | 20240716144123.651476-2-andrey.drobyshev@virtuozzo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix data corruption within preallocation | expand |
Am 16.07.2024 um 16:41 hat Andrey Drobyshev geschrieben: > From: "Denis V. Lunev" <den@openvz.org> > > We have observed that some clusters in the QCOW2 files are zeroed > while preallocation filter is used. > > We are able to trace down the following sequence when prealloc-filter > is used: > co=0x55e7cbed7680 qcow2_co_pwritev_task() > co=0x55e7cbed7680 preallocate_co_pwritev_part() > co=0x55e7cbed7680 handle_write() > co=0x55e7cbed7680 bdrv_co_do_pwrite_zeroes() > co=0x55e7cbed7680 raw_do_pwrite_zeroes() > co=0x7f9edb7fe500 do_fallocate() > > Here coroutine 0x55e7cbed7680 is being blocked waiting while coroutine > 0x7f9edb7fe500 will finish with fallocate of the file area. OK. It is > time to handle next coroutine, which > co=0x55e7cbee91b0 qcow2_co_pwritev_task() > co=0x55e7cbee91b0 preallocate_co_pwritev_part() > co=0x55e7cbee91b0 handle_write() > co=0x55e7cbee91b0 bdrv_co_do_pwrite_zeroes() > co=0x55e7cbee91b0 raw_do_pwrite_zeroes() > co=0x7f9edb7deb00 do_fallocate() > > The trouble comes here. Coroutine 0x55e7cbed7680 has not advanced > file_end yet and coroutine 0x55e7cbee91b0 will start fallocate() for > the same area. This means that if (once fallocate is started inside > 0x7f9edb7deb00) original fallocate could end and the real write will > be executed. In that case write() request is handled at the same time > as fallocate(). > > The patch moves s->file_lock assignment before fallocate and that is s/file_lock/file_end/? > crucial. The idea is that all subsequent requests into the area > being preallocation will be issued as just writes without fallocate > to this area and they will not proceed thanks to overlapping > requests mechanics. If preallocation will fail, we will just switch > to the normal expand-by-write behavior and that is not a problem > except performance. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > Tested-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> > --- > block/preallocate.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/block/preallocate.c b/block/preallocate.c > index d215bc5d6d..ecf0aa4baa 100644 > --- a/block/preallocate.c > +++ b/block/preallocate.c > @@ -383,6 +383,13 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, > > want_merge_zero = want_merge_zero && (prealloc_start <= offset); > > + /* > + * Assign file_end before making actual preallocation. This will ensure > + * that next request performed while preallocation is in progress will > + * be passed without preallocation. > + */ > + s->file_end = prealloc_end; > + > ret = bdrv_co_pwrite_zeroes( > bs->file, prealloc_start, prealloc_end - prealloc_start, > BDRV_REQ_NO_FALLBACK | BDRV_REQ_SERIALISING | BDRV_REQ_NO_WAIT); > @@ -391,7 +398,6 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, > return false; > } > > - s->file_end = prealloc_end; > return want_merge_zero; > } Until bdrv_co_pwrite_zeroes() completes successfully, the file size is unchanged. In other words, if anything calls preallocate_co_getlength() in the meantime, don't we run into... ret = bdrv_co_getlength(bs->file->bs); if (has_prealloc_perms(bs)) { s->file_end = s->zero_start = s->data_end = ret; } ...and reset s->file_end back to the old value, re-enabling the bug you're trying to fix here? Or do we know that no such code path can be called concurrently for some reason? Kevin
On 7/18/24 17:51, Kevin Wolf wrote: > Am 16.07.2024 um 16:41 hat Andrey Drobyshev geschrieben: >> From: "Denis V. Lunev" <den@openvz.org> >> >> We have observed that some clusters in the QCOW2 files are zeroed >> while preallocation filter is used. >> >> We are able to trace down the following sequence when prealloc-filter >> is used: >> co=0x55e7cbed7680 qcow2_co_pwritev_task() >> co=0x55e7cbed7680 preallocate_co_pwritev_part() >> co=0x55e7cbed7680 handle_write() >> co=0x55e7cbed7680 bdrv_co_do_pwrite_zeroes() >> co=0x55e7cbed7680 raw_do_pwrite_zeroes() >> co=0x7f9edb7fe500 do_fallocate() >> >> Here coroutine 0x55e7cbed7680 is being blocked waiting while coroutine >> 0x7f9edb7fe500 will finish with fallocate of the file area. OK. It is >> time to handle next coroutine, which >> co=0x55e7cbee91b0 qcow2_co_pwritev_task() >> co=0x55e7cbee91b0 preallocate_co_pwritev_part() >> co=0x55e7cbee91b0 handle_write() >> co=0x55e7cbee91b0 bdrv_co_do_pwrite_zeroes() >> co=0x55e7cbee91b0 raw_do_pwrite_zeroes() >> co=0x7f9edb7deb00 do_fallocate() >> >> The trouble comes here. Coroutine 0x55e7cbed7680 has not advanced >> file_end yet and coroutine 0x55e7cbee91b0 will start fallocate() for >> the same area. This means that if (once fallocate is started inside >> 0x7f9edb7deb00) original fallocate could end and the real write will >> be executed. In that case write() request is handled at the same time >> as fallocate(). >> >> The patch moves s->file_lock assignment before fallocate and that is > s/file_lock/file_end/? > >> crucial. The idea is that all subsequent requests into the area >> being preallocation will be issued as just writes without fallocate >> to this area and they will not proceed thanks to overlapping >> requests mechanics. If preallocation will fail, we will just switch >> to the normal expand-by-write behavior and that is not a problem >> except performance. >> >> Signed-off-by: Denis V. Lunev <den@openvz.org> >> Tested-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> >> --- >> block/preallocate.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/block/preallocate.c b/block/preallocate.c >> index d215bc5d6d..ecf0aa4baa 100644 >> --- a/block/preallocate.c >> +++ b/block/preallocate.c >> @@ -383,6 +383,13 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, >> >> want_merge_zero = want_merge_zero && (prealloc_start <= offset); >> >> + /* >> + * Assign file_end before making actual preallocation. This will ensure >> + * that next request performed while preallocation is in progress will >> + * be passed without preallocation. >> + */ >> + s->file_end = prealloc_end; >> + >> ret = bdrv_co_pwrite_zeroes( >> bs->file, prealloc_start, prealloc_end - prealloc_start, >> BDRV_REQ_NO_FALLBACK | BDRV_REQ_SERIALISING | BDRV_REQ_NO_WAIT); >> @@ -391,7 +398,6 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, >> return false; >> } >> >> - s->file_end = prealloc_end; >> return want_merge_zero; >> } > Until bdrv_co_pwrite_zeroes() completes successfully, the file size is > unchanged. In other words, if anything calls preallocate_co_getlength() > in the meantime, don't we run into... > > ret = bdrv_co_getlength(bs->file->bs); > > if (has_prealloc_perms(bs)) { > s->file_end = s->zero_start = s->data_end = ret; > } > > ...and reset s->file_end back to the old value, re-enabling the bug > you're trying to fix here? > > Or do we know that no such code path can be called concurrently for some > reason? > > Kevin > Truly amazing catch! Den
On 7/18/24 17:51, Kevin Wolf wrote: > Am 16.07.2024 um 16:41 hat Andrey Drobyshev geschrieben: >> From: "Denis V. Lunev" <den@openvz.org> >> >> We have observed that some clusters in the QCOW2 files are zeroed >> while preallocation filter is used. >> >> We are able to trace down the following sequence when prealloc-filter >> is used: >> co=0x55e7cbed7680 qcow2_co_pwritev_task() >> co=0x55e7cbed7680 preallocate_co_pwritev_part() >> co=0x55e7cbed7680 handle_write() >> co=0x55e7cbed7680 bdrv_co_do_pwrite_zeroes() >> co=0x55e7cbed7680 raw_do_pwrite_zeroes() >> co=0x7f9edb7fe500 do_fallocate() >> >> Here coroutine 0x55e7cbed7680 is being blocked waiting while coroutine >> 0x7f9edb7fe500 will finish with fallocate of the file area. OK. It is >> time to handle next coroutine, which >> co=0x55e7cbee91b0 qcow2_co_pwritev_task() >> co=0x55e7cbee91b0 preallocate_co_pwritev_part() >> co=0x55e7cbee91b0 handle_write() >> co=0x55e7cbee91b0 bdrv_co_do_pwrite_zeroes() >> co=0x55e7cbee91b0 raw_do_pwrite_zeroes() >> co=0x7f9edb7deb00 do_fallocate() >> >> The trouble comes here. Coroutine 0x55e7cbed7680 has not advanced >> file_end yet and coroutine 0x55e7cbee91b0 will start fallocate() for >> the same area. This means that if (once fallocate is started inside >> 0x7f9edb7deb00) original fallocate could end and the real write will >> be executed. In that case write() request is handled at the same time >> as fallocate(). >> >> The patch moves s->file_lock assignment before fallocate and that is > s/file_lock/file_end/? > >> crucial. The idea is that all subsequent requests into the area >> being preallocation will be issued as just writes without fallocate >> to this area and they will not proceed thanks to overlapping >> requests mechanics. If preallocation will fail, we will just switch >> to the normal expand-by-write behavior and that is not a problem >> except performance. >> >> Signed-off-by: Denis V. Lunev <den@openvz.org> >> Tested-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> >> --- >> block/preallocate.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/block/preallocate.c b/block/preallocate.c >> index d215bc5d6d..ecf0aa4baa 100644 >> --- a/block/preallocate.c >> +++ b/block/preallocate.c >> @@ -383,6 +383,13 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, >> >> want_merge_zero = want_merge_zero && (prealloc_start <= offset); >> >> + /* >> + * Assign file_end before making actual preallocation. This will ensure >> + * that next request performed while preallocation is in progress will >> + * be passed without preallocation. >> + */ >> + s->file_end = prealloc_end; >> + >> ret = bdrv_co_pwrite_zeroes( >> bs->file, prealloc_start, prealloc_end - prealloc_start, >> BDRV_REQ_NO_FALLBACK | BDRV_REQ_SERIALISING | BDRV_REQ_NO_WAIT); >> @@ -391,7 +398,6 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, >> return false; >> } >> >> - s->file_end = prealloc_end; >> return want_merge_zero; >> } > Until bdrv_co_pwrite_zeroes() completes successfully, the file size is > unchanged. In other words, if anything calls preallocate_co_getlength() > in the meantime, don't we run into... > > ret = bdrv_co_getlength(bs->file->bs); > > if (has_prealloc_perms(bs)) { > s->file_end = s->zero_start = s->data_end = ret; > } > > ...and reset s->file_end back to the old value, re-enabling the bug > you're trying to fix here? > > Or do we know that no such code path can be called concurrently for some > reason? > > Kevin > After more detailed thinking I tend to disagree. Normally we would not hit the problem. Though this was not obvious at the beginning :) The point in handle_write() where we move file_end assignment is reachable only if the following code has been executed if (s->data_end < 0) { s->data_end = bdrv_co_getlength(bs->file->bs); if (s->data_end < 0) { return false; } if (s->file_end < 0) { s->file_end = s->data_end; } } if (end <= s->data_end) { return false; } which means that s->data_end > 0. Thus static int64_t coroutine_fn GRAPH_RDLOCK preallocate_co_getlength(BlockDriverState *bs) { int64_t ret; BDRVPreallocateState *s = bs->opaque; if (s->data_end >= 0) { return s->data_end; <--- we will return here } ret = bdrv_co_getlength(bs->file->bs); if (has_prealloc_perms(bs)) { s->file_end = s->zero_start = s->data_end = ret; } return ret; } Den
Am 18.07.2024 um 21:46 hat Denis V. Lunev geschrieben: > On 7/18/24 17:51, Kevin Wolf wrote: > > Am 16.07.2024 um 16:41 hat Andrey Drobyshev geschrieben: > > > From: "Denis V. Lunev" <den@openvz.org> > > > > > > We have observed that some clusters in the QCOW2 files are zeroed > > > while preallocation filter is used. > > > > > > We are able to trace down the following sequence when prealloc-filter > > > is used: > > > co=0x55e7cbed7680 qcow2_co_pwritev_task() > > > co=0x55e7cbed7680 preallocate_co_pwritev_part() > > > co=0x55e7cbed7680 handle_write() > > > co=0x55e7cbed7680 bdrv_co_do_pwrite_zeroes() > > > co=0x55e7cbed7680 raw_do_pwrite_zeroes() > > > co=0x7f9edb7fe500 do_fallocate() > > > > > > Here coroutine 0x55e7cbed7680 is being blocked waiting while coroutine > > > 0x7f9edb7fe500 will finish with fallocate of the file area. OK. It is > > > time to handle next coroutine, which > > > co=0x55e7cbee91b0 qcow2_co_pwritev_task() > > > co=0x55e7cbee91b0 preallocate_co_pwritev_part() > > > co=0x55e7cbee91b0 handle_write() > > > co=0x55e7cbee91b0 bdrv_co_do_pwrite_zeroes() > > > co=0x55e7cbee91b0 raw_do_pwrite_zeroes() > > > co=0x7f9edb7deb00 do_fallocate() > > > > > > The trouble comes here. Coroutine 0x55e7cbed7680 has not advanced > > > file_end yet and coroutine 0x55e7cbee91b0 will start fallocate() for > > > the same area. This means that if (once fallocate is started inside > > > 0x7f9edb7deb00) original fallocate could end and the real write will > > > be executed. In that case write() request is handled at the same time > > > as fallocate(). > > > > > > The patch moves s->file_lock assignment before fallocate and that is > > s/file_lock/file_end/? > > > > > crucial. The idea is that all subsequent requests into the area > > > being preallocation will be issued as just writes without fallocate > > > to this area and they will not proceed thanks to overlapping > > > requests mechanics. If preallocation will fail, we will just switch > > > to the normal expand-by-write behavior and that is not a problem > > > except performance. > > > > > > Signed-off-by: Denis V. Lunev <den@openvz.org> > > > Tested-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> > > > --- > > > block/preallocate.c | 8 +++++++- > > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > > > diff --git a/block/preallocate.c b/block/preallocate.c > > > index d215bc5d6d..ecf0aa4baa 100644 > > > --- a/block/preallocate.c > > > +++ b/block/preallocate.c > > > @@ -383,6 +383,13 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, > > > want_merge_zero = want_merge_zero && (prealloc_start <= offset); > > > + /* > > > + * Assign file_end before making actual preallocation. This will ensure > > > + * that next request performed while preallocation is in progress will > > > + * be passed without preallocation. > > > + */ > > > + s->file_end = prealloc_end; > > > + > > > ret = bdrv_co_pwrite_zeroes( > > > bs->file, prealloc_start, prealloc_end - prealloc_start, > > > BDRV_REQ_NO_FALLBACK | BDRV_REQ_SERIALISING | BDRV_REQ_NO_WAIT); > > > @@ -391,7 +398,6 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, > > > return false; > > > } > > > - s->file_end = prealloc_end; > > > return want_merge_zero; > > > } > > Until bdrv_co_pwrite_zeroes() completes successfully, the file size is > > unchanged. In other words, if anything calls preallocate_co_getlength() > > in the meantime, don't we run into... > > > > ret = bdrv_co_getlength(bs->file->bs); > > > > if (has_prealloc_perms(bs)) { > > s->file_end = s->zero_start = s->data_end = ret; > > } > > > > ...and reset s->file_end back to the old value, re-enabling the bug > > you're trying to fix here? > > > > Or do we know that no such code path can be called concurrently for some > > reason? > > > > Kevin > > > After more detailed thinking I tend to disagree. > Normally we would not hit the problem. Though > this was not obvious at the beginning :) > > The point in handle_write() where we move > file_end assignment is reachable only if the > following code has been executed > > if (s->data_end < 0) { > s->data_end = bdrv_co_getlength(bs->file->bs); > if (s->data_end < 0) { > return false; > } > > if (s->file_end < 0) { > s->file_end = s->data_end; > } > } > > if (end <= s->data_end) { > return false; > } > > which means that s->data_end > 0. > > Thus > > static int64_t coroutine_fn GRAPH_RDLOCK > preallocate_co_getlength(BlockDriverState *bs) > { > int64_t ret; > BDRVPreallocateState *s = bs->opaque; > > if (s->data_end >= 0) { > return s->data_end; <--- we will return here > } > > ret = bdrv_co_getlength(bs->file->bs); > > if (has_prealloc_perms(bs)) { > s->file_end = s->zero_start = s->data_end = ret; > } > > return ret; > } I think you're right there. And the other places that update s->file_end should probably be okay because of the request serialisation. I'm okay with applying this patch as it seems to fix a corruption, but the way this whole block driver operates doesn't feel very robust to me. There seem to be a lot of implicit assumptions that make the code hard to understand even though it's quite short. Kevin
On 8/5/24 13:59, Kevin Wolf wrote: > Am 18.07.2024 um 21:46 hat Denis V. Lunev geschrieben: >> On 7/18/24 17:51, Kevin Wolf wrote: >>> Am 16.07.2024 um 16:41 hat Andrey Drobyshev geschrieben: >>>> From: "Denis V. Lunev" <den@openvz.org> >>>> >>>> We have observed that some clusters in the QCOW2 files are zeroed >>>> while preallocation filter is used. >>>> >>>> We are able to trace down the following sequence when prealloc-filter >>>> is used: >>>> co=0x55e7cbed7680 qcow2_co_pwritev_task() >>>> co=0x55e7cbed7680 preallocate_co_pwritev_part() >>>> co=0x55e7cbed7680 handle_write() >>>> co=0x55e7cbed7680 bdrv_co_do_pwrite_zeroes() >>>> co=0x55e7cbed7680 raw_do_pwrite_zeroes() >>>> co=0x7f9edb7fe500 do_fallocate() >>>> >>>> Here coroutine 0x55e7cbed7680 is being blocked waiting while coroutine >>>> 0x7f9edb7fe500 will finish with fallocate of the file area. OK. It is >>>> time to handle next coroutine, which >>>> co=0x55e7cbee91b0 qcow2_co_pwritev_task() >>>> co=0x55e7cbee91b0 preallocate_co_pwritev_part() >>>> co=0x55e7cbee91b0 handle_write() >>>> co=0x55e7cbee91b0 bdrv_co_do_pwrite_zeroes() >>>> co=0x55e7cbee91b0 raw_do_pwrite_zeroes() >>>> co=0x7f9edb7deb00 do_fallocate() >>>> >>>> The trouble comes here. Coroutine 0x55e7cbed7680 has not advanced >>>> file_end yet and coroutine 0x55e7cbee91b0 will start fallocate() for >>>> the same area. This means that if (once fallocate is started inside >>>> 0x7f9edb7deb00) original fallocate could end and the real write will >>>> be executed. In that case write() request is handled at the same time >>>> as fallocate(). >>>> >>>> The patch moves s->file_lock assignment before fallocate and that is >>> s/file_lock/file_end/? >>> >>>> crucial. The idea is that all subsequent requests into the area >>>> being preallocation will be issued as just writes without fallocate >>>> to this area and they will not proceed thanks to overlapping >>>> requests mechanics. If preallocation will fail, we will just switch >>>> to the normal expand-by-write behavior and that is not a problem >>>> except performance. >>>> >>>> Signed-off-by: Denis V. Lunev <den@openvz.org> >>>> Tested-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> >>>> --- >>>> block/preallocate.c | 8 +++++++- >>>> 1 file changed, 7 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/block/preallocate.c b/block/preallocate.c >>>> index d215bc5d6d..ecf0aa4baa 100644 >>>> --- a/block/preallocate.c >>>> +++ b/block/preallocate.c >>>> @@ -383,6 +383,13 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, >>>> want_merge_zero = want_merge_zero && (prealloc_start <= offset); >>>> + /* >>>> + * Assign file_end before making actual preallocation. This will ensure >>>> + * that next request performed while preallocation is in progress will >>>> + * be passed without preallocation. >>>> + */ >>>> + s->file_end = prealloc_end; >>>> + >>>> ret = bdrv_co_pwrite_zeroes( >>>> bs->file, prealloc_start, prealloc_end - prealloc_start, >>>> BDRV_REQ_NO_FALLBACK | BDRV_REQ_SERIALISING | BDRV_REQ_NO_WAIT); >>>> @@ -391,7 +398,6 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, >>>> return false; >>>> } >>>> - s->file_end = prealloc_end; >>>> return want_merge_zero; >>>> } >>> Until bdrv_co_pwrite_zeroes() completes successfully, the file size is >>> unchanged. In other words, if anything calls preallocate_co_getlength() >>> in the meantime, don't we run into... >>> >>> ret = bdrv_co_getlength(bs->file->bs); >>> >>> if (has_prealloc_perms(bs)) { >>> s->file_end = s->zero_start = s->data_end = ret; >>> } >>> >>> ...and reset s->file_end back to the old value, re-enabling the bug >>> you're trying to fix here? >>> >>> Or do we know that no such code path can be called concurrently for some >>> reason? >>> >>> Kevin >>> >> After more detailed thinking I tend to disagree. >> Normally we would not hit the problem. Though >> this was not obvious at the beginning :) >> >> The point in handle_write() where we move >> file_end assignment is reachable only if the >> following code has been executed >> >> if (s->data_end < 0) { >> s->data_end = bdrv_co_getlength(bs->file->bs); >> if (s->data_end < 0) { >> return false; >> } >> >> if (s->file_end < 0) { >> s->file_end = s->data_end; >> } >> } >> >> if (end <= s->data_end) { >> return false; >> } >> >> which means that s->data_end > 0. >> >> Thus >> >> static int64_t coroutine_fn GRAPH_RDLOCK >> preallocate_co_getlength(BlockDriverState *bs) >> { >> int64_t ret; >> BDRVPreallocateState *s = bs->opaque; >> >> if (s->data_end >= 0) { >> return s->data_end; <--- we will return here >> } >> >> ret = bdrv_co_getlength(bs->file->bs); >> >> if (has_prealloc_perms(bs)) { >> s->file_end = s->zero_start = s->data_end = ret; >> } >> >> return ret; >> } > I think you're right there. And the other places that update s->file_end > should probably be okay because of the request serialisation. > > I'm okay with applying this patch as it seems to fix a corruption, but > the way this whole block driver operates doesn't feel very robust to me. > There seem to be a lot of implicit assumptions that make the code hard > to understand even though it's quite short. > > Kevin > There are a lot of things to make a change. I'll definitely have to address this later. Working on that. For now the patch is working in downstream and it seems OK. Thank you in advance, Den
diff --git a/block/preallocate.c b/block/preallocate.c index d215bc5d6d..ecf0aa4baa 100644 --- a/block/preallocate.c +++ b/block/preallocate.c @@ -383,6 +383,13 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, want_merge_zero = want_merge_zero && (prealloc_start <= offset); + /* + * Assign file_end before making actual preallocation. This will ensure + * that next request performed while preallocation is in progress will + * be passed without preallocation. + */ + s->file_end = prealloc_end; + ret = bdrv_co_pwrite_zeroes( bs->file, prealloc_start, prealloc_end - prealloc_start, BDRV_REQ_NO_FALLBACK | BDRV_REQ_SERIALISING | BDRV_REQ_NO_WAIT); @@ -391,7 +398,6 @@ handle_write(BlockDriverState *bs, int64_t offset, int64_t bytes, return false; } - s->file_end = prealloc_end; return want_merge_zero; }