| Message ID | 20180913023134.3853-1-yuchenlin@synology.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] vmdk: align end of file to a sector boundary | expand |
On Thu, 09/13 10:31, yuchenlin@synology.com wrote: > From: yuchenlin <yuchenlin@synology.com> > > There is a rare case which the size of last compressed cluster > is larger than the cluster size, which will cause the file is > not aligned at the sector boundary. The code looks good to me. Can you also explain why it is important to align file size to sector boundary in the comment? Fam > > Signed-off-by: yuchenlin <yuchenlin@synology.com> > --- > v1 -> v2: > * Add more detail comment. > * Add QEMU_ALIGN_UP to show the intention more clearly. > * Add newline in the end of bdrv_truncate. > > thanks > > block/vmdk.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/block/vmdk.c b/block/vmdk.c > index a9d0084e36..2c9e86d98f 100644 > --- a/block/vmdk.c > +++ b/block/vmdk.c > @@ -1698,6 +1698,27 @@ static int coroutine_fn > vmdk_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, > uint64_t bytes, QEMUIOVector *qiov) > { > + if (bytes == 0) { > + /* The caller will write bytes 0 to signal EOF. > + * When receive it, we align EOF to a sector boundary. */ > + BDRVVmdkState *s = bs->opaque; > + int i, ret; > + int64_t length; > + > + for (i = 0; i < s->num_extents; i++) { > + length = bdrv_getlength(s->extents[i].file->bs); > + if (length < 0) { > + return length; > + } > + length = QEMU_ALIGN_UP(length, BDRV_SECTOR_SIZE); > + ret = bdrv_truncate(s->extents[i].file, length, > + PREALLOC_MODE_OFF, NULL); > + if (ret < 0) { > + return ret; > + } > + } > + return 0; > + } > return vmdk_co_pwritev(bs, offset, bytes, qiov, 0); > } > > -- > 2.18.0 >
On 2018-09-13 10:54, Fam Zheng wrote: > On Thu, 09/13 10:31, yuchenlin@synology.com wrote: >> From: yuchenlin <yuchenlin@synology.com> >> >> There is a rare case which the size of last compressed cluster >> is larger than the cluster size, which will cause the file is >> not aligned at the sector boundary. > > The code looks good to me. Can you also explain why it is important to > align > file size to sector boundary in the comment? > > Fam > In my opinion, there are three reasons to do it. First, if vmdk doesn't align at the sector boundary, there may be many undefined behaviors, such as in vbox it will show VMDK: Compressed image is corrupted '88-disk1.vmdk' (VERR_ZIP_CORRUPTED) when we try to import an ova with unaligned vmdk. Second, all the cluster_sector is aligned to sector, the last one should be like this, too. Third, it ease reading with sector based I/Os. What do you think? yuchenlin >> >> Signed-off-by: yuchenlin <yuchenlin@synology.com> >> --- >> v1 -> v2: >> * Add more detail comment. >> * Add QEMU_ALIGN_UP to show the intention more clearly. >> * Add newline in the end of bdrv_truncate. >> >> thanks >> >> block/vmdk.c | 21 +++++++++++++++++++++ >> 1 file changed, 21 insertions(+) >> >> diff --git a/block/vmdk.c b/block/vmdk.c >> index a9d0084e36..2c9e86d98f 100644 >> --- a/block/vmdk.c >> +++ b/block/vmdk.c >> @@ -1698,6 +1698,27 @@ static int coroutine_fn >> vmdk_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, >> uint64_t bytes, QEMUIOVector *qiov) >> { >> + if (bytes == 0) { >> + /* The caller will write bytes 0 to signal EOF. >> + * When receive it, we align EOF to a sector boundary. */ >> + BDRVVmdkState *s = bs->opaque; >> + int i, ret; >> + int64_t length; >> + >> + for (i = 0; i < s->num_extents; i++) { >> + length = bdrv_getlength(s->extents[i].file->bs); >> + if (length < 0) { >> + return length; >> + } >> + length = QEMU_ALIGN_UP(length, BDRV_SECTOR_SIZE); >> + ret = bdrv_truncate(s->extents[i].file, length, >> + PREALLOC_MODE_OFF, NULL); >> + if (ret < 0) { >> + return ret; >> + } >> + } >> + return 0; >> + } >> return vmdk_co_pwritev(bs, offset, bytes, qiov, 0); >> } >> >> -- >> 2.18.0 >>
On Thu, 09/13 15:47, yuchenlin wrote: > On 2018-09-13 10:54, Fam Zheng wrote: > > On Thu, 09/13 10:31, yuchenlin@synology.com wrote: > > > From: yuchenlin <yuchenlin@synology.com> > > > > > > There is a rare case which the size of last compressed cluster > > > is larger than the cluster size, which will cause the file is > > > not aligned at the sector boundary. > > > > The code looks good to me. Can you also explain why it is important to > > align > > file size to sector boundary in the comment? > > > > Fam > > > > In my opinion, there are three reasons to do it. First, if vmdk doesn't > align at the sector boundary, there may be many undefined behaviors, such as > in vbox it will show VMDK: Compressed image is corrupted '88-disk1.vmdk' > (VERR_ZIP_CORRUPTED) when we try to import an ova with unaligned vmdk. > Second, all the cluster_sector is aligned > to sector, the last one should be like this, too. Third, it ease reading > with sector based I/Os. > > What do you think? Yes, it would be nice if you could add this information to the commit message or the code comment. Fam > > yuchenlin > > > > > > > Signed-off-by: yuchenlin <yuchenlin@synology.com> > > > --- > > > v1 -> v2: > > > * Add more detail comment. > > > * Add QEMU_ALIGN_UP to show the intention more clearly. > > > * Add newline in the end of bdrv_truncate. > > > > > > thanks > > > > > > block/vmdk.c | 21 +++++++++++++++++++++ > > > 1 file changed, 21 insertions(+) > > > > > > diff --git a/block/vmdk.c b/block/vmdk.c > > > index a9d0084e36..2c9e86d98f 100644 > > > --- a/block/vmdk.c > > > +++ b/block/vmdk.c > > > @@ -1698,6 +1698,27 @@ static int coroutine_fn > > > vmdk_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, > > > uint64_t bytes, QEMUIOVector *qiov) > > > { > > > + if (bytes == 0) { > > > + /* The caller will write bytes 0 to signal EOF. > > > + * When receive it, we align EOF to a sector boundary. */ > > > + BDRVVmdkState *s = bs->opaque; > > > + int i, ret; > > > + int64_t length; > > > + > > > + for (i = 0; i < s->num_extents; i++) { > > > + length = bdrv_getlength(s->extents[i].file->bs); > > > + if (length < 0) { > > > + return length; > > > + } > > > + length = QEMU_ALIGN_UP(length, BDRV_SECTOR_SIZE); > > > + ret = bdrv_truncate(s->extents[i].file, length, > > > + PREALLOC_MODE_OFF, NULL); > > > + if (ret < 0) { > > > + return ret; > > > + } > > > + } > > > + return 0; > > > + } > > > return vmdk_co_pwritev(bs, offset, bytes, qiov, 0); > > > } > > > > > > -- > > > 2.18.0 > > > >
diff --git a/block/vmdk.c b/block/vmdk.c index a9d0084e36..2c9e86d98f 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -1698,6 +1698,27 @@ static int coroutine_fn vmdk_co_pwritev_compressed(BlockDriverState *bs, uint64_t offset, uint64_t bytes, QEMUIOVector *qiov) { + if (bytes == 0) { + /* The caller will write bytes 0 to signal EOF. + * When receive it, we align EOF to a sector boundary. */ + BDRVVmdkState *s = bs->opaque; + int i, ret; + int64_t length; + + for (i = 0; i < s->num_extents; i++) { + length = bdrv_getlength(s->extents[i].file->bs); + if (length < 0) { + return length; + } + length = QEMU_ALIGN_UP(length, BDRV_SECTOR_SIZE); + ret = bdrv_truncate(s->extents[i].file, length, + PREALLOC_MODE_OFF, NULL); + if (ret < 0) { + return ret; + } + } + return 0; + } return vmdk_co_pwritev(bs, offset, bytes, qiov, 0); }