| Message ID | 20230907215326.367847-1-den@openvz.org |
|---|---|
| State | New |
| Headers | show |
| Series | [1/1] block: improve alignment detection and fix 271 test | expand |
On 9/7/23 23:53, Denis V. Lunev wrote: > Unfortunately 271 IO test is broken if started in non-cached mode. > > Commits > commit a6b257a08e3d72219f03e461a52152672fec0612 > Author: Nir Soffer <nirsof@gmail.com> > Date: Tue Aug 13 21:21:03 2019 +0300 > file-posix: Handle undetectable alignment > and > commit 9c60a5d1978e6dcf85c0e01b50e6f7f54ca09104 > Author: Kevin Wolf <kwolf@redhat.com> > Date: Thu Jul 16 16:26:00 2020 +0200 > block: Require aligned image size to avoid assertion failure > have interesting side effect if used togather. > > If the image size is not multiple of 4k and that image falls under > original constraints of Nil's patch, the image can not be opened > due to the check in the bdrv_check_perm(). > > The patch tries to satisfy the requirements of bdrv_check_perm() > inside raw_probe_alignment(). This is at my opinion better that just > disallowing to run that test in non-cached mode. The operation is legal > by itself. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Nir Soffer <nirsof@gmail.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Hanna Reitz <hreitz@redhat.com> > CC: Alberto Garcia <berto@igalia.com> > --- > block/file-posix.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/block/file-posix.c b/block/file-posix.c > index b16e9c21a1..988cfdc76c 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -447,8 +447,21 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) > for (i = 0; i < ARRAY_SIZE(alignments); i++) { > align = alignments[i]; > if (raw_is_io_aligned(fd, buf, align)) { > - /* Fallback to safe value. */ > - bs->bl.request_alignment = (align != 1) ? align : max_align; > + if (align != 1) { > + bs->bl.request_alignment = align; > + break; > + } > + /* > + * Fallback to safe value. max_align is perfect, but the size of the device must be multiple of > + * the virtual length of the device. In the other case we will get a error in > + * bdrv_node_refresh_perm(). > + */ > + for (align = max_align; align > 1; align /= 2) { > + if ((bs->total_sectors * BDRV_SECTOR_SIZE) % align == 0) { > + break; > + } > + } > + bs->bl.request_alignment = align; > break; > } > } ping
On 9/7/23 23:53, Denis V. Lunev wrote: > Unfortunately 271 IO test is broken if started in non-cached mode. > > Commits > commit a6b257a08e3d72219f03e461a52152672fec0612 > Author: Nir Soffer <nirsof@gmail.com> > Date: Tue Aug 13 21:21:03 2019 +0300 > file-posix: Handle undetectable alignment > and > commit 9c60a5d1978e6dcf85c0e01b50e6f7f54ca09104 > Author: Kevin Wolf <kwolf@redhat.com> > Date: Thu Jul 16 16:26:00 2020 +0200 > block: Require aligned image size to avoid assertion failure > have interesting side effect if used togather. > > If the image size is not multiple of 4k and that image falls under > original constraints of Nil's patch, the image can not be opened > due to the check in the bdrv_check_perm(). > > The patch tries to satisfy the requirements of bdrv_check_perm() > inside raw_probe_alignment(). This is at my opinion better that just > disallowing to run that test in non-cached mode. The operation is legal > by itself. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Nir Soffer <nirsof@gmail.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Hanna Reitz <hreitz@redhat.com> > CC: Alberto Garcia <berto@igalia.com> > --- > block/file-posix.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/block/file-posix.c b/block/file-posix.c > index b16e9c21a1..988cfdc76c 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -447,8 +447,21 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) > for (i = 0; i < ARRAY_SIZE(alignments); i++) { > align = alignments[i]; > if (raw_is_io_aligned(fd, buf, align)) { > - /* Fallback to safe value. */ > - bs->bl.request_alignment = (align != 1) ? align : max_align; > + if (align != 1) { > + bs->bl.request_alignment = align; > + break; > + } > + /* > + * Fallback to safe value. max_align is perfect, but the size of the device must be multiple of > + * the virtual length of the device. In the other case we will get a error in > + * bdrv_node_refresh_perm(). > + */ > + for (align = max_align; align > 1; align /= 2) { > + if ((bs->total_sectors * BDRV_SECTOR_SIZE) % align == 0) { > + break; > + } > + } > + bs->bl.request_alignment = align; > break; > } > } ping v2
On 9/7/23 23:53, Denis V. Lunev wrote: > Unfortunately 271 IO test is broken if started in non-cached mode. > > Commits > commit a6b257a08e3d72219f03e461a52152672fec0612 > Author: Nir Soffer <nirsof@gmail.com> > Date: Tue Aug 13 21:21:03 2019 +0300 > file-posix: Handle undetectable alignment > and > commit 9c60a5d1978e6dcf85c0e01b50e6f7f54ca09104 > Author: Kevin Wolf <kwolf@redhat.com> > Date: Thu Jul 16 16:26:00 2020 +0200 > block: Require aligned image size to avoid assertion failure > have interesting side effect if used togather. > > If the image size is not multiple of 4k and that image falls under > original constraints of Nil's patch, the image can not be opened > due to the check in the bdrv_check_perm(). > > The patch tries to satisfy the requirements of bdrv_check_perm() > inside raw_probe_alignment(). This is at my opinion better that just > disallowing to run that test in non-cached mode. The operation is legal > by itself. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Nir Soffer <nirsof@gmail.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Hanna Reitz <hreitz@redhat.com> > CC: Alberto Garcia <berto@igalia.com> > --- > block/file-posix.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/block/file-posix.c b/block/file-posix.c > index b16e9c21a1..988cfdc76c 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -447,8 +447,21 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) > for (i = 0; i < ARRAY_SIZE(alignments); i++) { > align = alignments[i]; > if (raw_is_io_aligned(fd, buf, align)) { > - /* Fallback to safe value. */ > - bs->bl.request_alignment = (align != 1) ? align : max_align; > + if (align != 1) { > + bs->bl.request_alignment = align; > + break; > + } > + /* > + * Fallback to safe value. max_align is perfect, but the size of the device must be multiple of > + * the virtual length of the device. In the other case we will get a error in > + * bdrv_node_refresh_perm(). > + */ > + for (align = max_align; align > 1; align /= 2) { > + if ((bs->total_sectors * BDRV_SECTOR_SIZE) % align == 0) { > + break; > + } > + } > + bs->bl.request_alignment = align; > break; > } > } ping v3
On 9/7/23 23:53, Denis V. Lunev wrote: > Unfortunately 271 IO test is broken if started in non-cached mode. > > Commits > commit a6b257a08e3d72219f03e461a52152672fec0612 > Author: Nir Soffer <nirsof@gmail.com> > Date: Tue Aug 13 21:21:03 2019 +0300 > file-posix: Handle undetectable alignment > and > commit 9c60a5d1978e6dcf85c0e01b50e6f7f54ca09104 > Author: Kevin Wolf <kwolf@redhat.com> > Date: Thu Jul 16 16:26:00 2020 +0200 > block: Require aligned image size to avoid assertion failure > have interesting side effect if used togather. > > If the image size is not multiple of 4k and that image falls under > original constraints of Nil's patch, the image can not be opened > due to the check in the bdrv_check_perm(). > > The patch tries to satisfy the requirements of bdrv_check_perm() > inside raw_probe_alignment(). This is at my opinion better that just > disallowing to run that test in non-cached mode. The operation is legal > by itself. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Nir Soffer <nirsof@gmail.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Hanna Reitz <hreitz@redhat.com> > CC: Alberto Garcia <berto@igalia.com> > --- > block/file-posix.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/block/file-posix.c b/block/file-posix.c > index b16e9c21a1..988cfdc76c 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -447,8 +447,21 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) > for (i = 0; i < ARRAY_SIZE(alignments); i++) { > align = alignments[i]; > if (raw_is_io_aligned(fd, buf, align)) { > - /* Fallback to safe value. */ > - bs->bl.request_alignment = (align != 1) ? align : max_align; > + if (align != 1) { > + bs->bl.request_alignment = align; > + break; > + } > + /* > + * Fallback to safe value. max_align is perfect, but the size of the device must be multiple of > + * the virtual length of the device. In the other case we will get a error in > + * bdrv_node_refresh_perm(). > + */ > + for (align = max_align; align > 1; align /= 2) { > + if ((bs->total_sectors * BDRV_SECTOR_SIZE) % align == 0) { > + break; > + } > + } > + bs->bl.request_alignment = align; > break; > } > } ping
On Fri, Sep 8, 2023 at 12:54 AM Denis V. Lunev <den@openvz.org> wrote: > Unfortunately 271 IO test is broken if started in non-cached mode. > Is this a real world issue? For example in oVirt you cannot create a disk with size < 4k so there is no way that 4k is not a good alignment. Should we fix the test to reflect real world usage? _reset_img 2083k I guess it works with: _reset_img 2084k Commits > commit a6b257a08e3d72219f03e461a52152672fec0612 > Author: Nir Soffer <nirsof@gmail.com> > Date: Tue Aug 13 21:21:03 2019 +0300 > file-posix: Handle undetectable alignment > and > commit 9c60a5d1978e6dcf85c0e01b50e6f7f54ca09104 > Author: Kevin Wolf <kwolf@redhat.com> > Date: Thu Jul 16 16:26:00 2020 +0200 > block: Require aligned image size to avoid assertion failure > have interesting side effect if used togather. > > If the image size is not multiple of 4k and that image falls under > original constraints of Nil's patch, the image can not be opened > due to the check in the bdrv_check_perm(). > > The patch tries to satisfy the requirements of bdrv_check_perm() > inside raw_probe_alignment(). This is at my opinion better that just > disallowing to run that test in non-cached mode. The operation is legal > by itself. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Nir Soffer <nirsof@gmail.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Hanna Reitz <hreitz@redhat.com> > CC: Alberto Garcia <berto@igalia.com> > --- > block/file-posix.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff --git a/block/file-posix.c b/block/file-posix.c > index b16e9c21a1..988cfdc76c 100644 > --- a/block/file-posix.c > +++ b/block/file-posix.c > @@ -447,8 +447,21 @@ static void raw_probe_alignment(BlockDriverState *bs, > int fd, Error **errp) > for (i = 0; i < ARRAY_SIZE(alignments); i++) { > align = alignments[i]; > if (raw_is_io_aligned(fd, buf, align)) { > - /* Fallback to safe value. */ > - bs->bl.request_alignment = (align != 1) ? align : > max_align; > + if (align != 1) { > + bs->bl.request_alignment = align; > + break; > + } > + /* > + * Fallback to safe value. max_align is perfect, but the > size of the device must be multiple of > + * the virtual length of the device. In the other case we > will get a error in > + * bdrv_node_refresh_perm(). > + */ > + for (align = max_align; align > 1; align /= 2) { > + if ((bs->total_sectors * BDRV_SECTOR_SIZE) % align == > 0) { > Moving image size calculation out of the loop would make the intent of the code more clear: if (image_size % align == 0) { Since qemu does not enforce image size alignment, I can see how you create a 512 bytes aligned image and in the case when qemu cannot detect the alignment, we end with align = 4k. In this case this loop would select align = 512, but with the image aligned to some strange value, this loop may select align = 2 or some other value that does not make sense. So I can see using 4k or 512 bytes as a good fallback value, but anything else should not be possible, so maybe we should fix this in bdrv_check_perm()? Nir
diff --git a/block/file-posix.c b/block/file-posix.c index b16e9c21a1..988cfdc76c 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -447,8 +447,21 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp) for (i = 0; i < ARRAY_SIZE(alignments); i++) { align = alignments[i]; if (raw_is_io_aligned(fd, buf, align)) { - /* Fallback to safe value. */ - bs->bl.request_alignment = (align != 1) ? align : max_align; + if (align != 1) { + bs->bl.request_alignment = align; + break; + } + /* + * Fallback to safe value. max_align is perfect, but the size of the device must be multiple of + * the virtual length of the device. In the other case we will get a error in + * bdrv_node_refresh_perm(). + */ + for (align = max_align; align > 1; align /= 2) { + if ((bs->total_sectors * BDRV_SECTOR_SIZE) % align == 0) { + break; + } + } + bs->bl.request_alignment = align; break; } }
Unfortunately 271 IO test is broken if started in non-cached mode. Commits commit a6b257a08e3d72219f03e461a52152672fec0612 Author: Nir Soffer <nirsof@gmail.com> Date: Tue Aug 13 21:21:03 2019 +0300 file-posix: Handle undetectable alignment and commit 9c60a5d1978e6dcf85c0e01b50e6f7f54ca09104 Author: Kevin Wolf <kwolf@redhat.com> Date: Thu Jul 16 16:26:00 2020 +0200 block: Require aligned image size to avoid assertion failure have interesting side effect if used togather. If the image size is not multiple of 4k and that image falls under original constraints of Nil's patch, the image can not be opened due to the check in the bdrv_check_perm(). The patch tries to satisfy the requirements of bdrv_check_perm() inside raw_probe_alignment(). This is at my opinion better that just disallowing to run that test in non-cached mode. The operation is legal by itself. Signed-off-by: Denis V. Lunev <den@openvz.org> CC: Nir Soffer <nirsof@gmail.com> CC: Kevin Wolf <kwolf@redhat.com> CC: Hanna Reitz <hreitz@redhat.com> CC: Alberto Garcia <berto@igalia.com> --- block/file-posix.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)