| Message ID | 20230626160834.696680-3-andrey.drobyshev@virtuozzo.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: align CoR requests to subclusters | expand |
On Mon, Jun 26, 2023 at 07:08:33PM +0300, Andrey Drobyshev via wrote: > When target image is using subclusters, and we align the request during > copy-on-read, it makes sense to align to subcluster_size rather than > cluster_size. Otherwise we end up with unnecessary allocations. > > This commit renames bdrv_round_to_clusters() to bdrv_round_to_subclusters() > and utilizes subcluster_size field of BlockDriverInfo to make necessary > alignments. It affects copy-on-read as well as mirror job (which is > using bdrv_round_to_clusters()). > > This change also fixes the following bug with failing assert (covered by > the test in the subsequent commit): > > qemu-img create -f qcow2 base.qcow2 64K > qemu-img create -f qcow2 -o extended_l2=on,backing_file=base.qcow2,backing_fmt=qcow2 img.qcow2 64K > qemu-io -c "write -P 0xaa 0 2K" img.qcow2 > qemu-io -C -c "read -P 0x00 2K 62K" img.qcow2 > > qemu-io: ../block/io.c:1236: bdrv_co_do_copy_on_readv: Assertion `skip_bytes < pnum' failed. > > Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> > --- > block/io.c | 50 ++++++++++++++++++++-------------------- > block/mirror.c | 8 +++---- > include/block/block-io.h | 2 +- > 3 files changed, 30 insertions(+), 30 deletions(-) > > +++ b/include/block/block-io.h > @@ -189,7 +189,7 @@ bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi); > ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, > Error **errp); > BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs); > -void bdrv_round_to_clusters(BlockDriverState *bs, > +void bdrv_round_to_subclusters(BlockDriverState *bs, > int64_t offset, int64_t bytes, > int64_t *cluster_offset, > int64_t *cluster_bytes); Indentation on subsequent lines should be fixed. Reviewed-by: Eric Blake <eblake@redhat.com>
On 6/26/23 18:08, Andrey Drobyshev wrote: > When target image is using subclusters, and we align the request during > copy-on-read, it makes sense to align to subcluster_size rather than > cluster_size. Otherwise we end up with unnecessary allocations. > > This commit renames bdrv_round_to_clusters() to bdrv_round_to_subclusters() > and utilizes subcluster_size field of BlockDriverInfo to make necessary > alignments. It affects copy-on-read as well as mirror job (which is > using bdrv_round_to_clusters()). > > This change also fixes the following bug with failing assert (covered by > the test in the subsequent commit): > > qemu-img create -f qcow2 base.qcow2 64K > qemu-img create -f qcow2 -o extended_l2=on,backing_file=base.qcow2,backing_fmt=qcow2 img.qcow2 64K > qemu-io -c "write -P 0xaa 0 2K" img.qcow2 > qemu-io -C -c "read -P 0x00 2K 62K" img.qcow2 > > qemu-io: ../block/io.c:1236: bdrv_co_do_copy_on_readv: Assertion `skip_bytes < pnum' failed. > > Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> > --- > block/io.c | 50 ++++++++++++++++++++-------------------- > block/mirror.c | 8 +++---- > include/block/block-io.h | 2 +- > 3 files changed, 30 insertions(+), 30 deletions(-) > > diff --git a/block/io.c b/block/io.c > index 30748f0b59..f1f8fad409 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -728,21 +728,21 @@ BdrvTrackedRequest *coroutine_fn bdrv_co_get_self_request(BlockDriverState *bs) > } > > /** > - * Round a region to cluster boundaries > + * Round a region to subcluster (if supported) or cluster boundaries > */ > void coroutine_fn GRAPH_RDLOCK > -bdrv_round_to_clusters(BlockDriverState *bs, int64_t offset, int64_t bytes, > - int64_t *cluster_offset, int64_t *cluster_bytes) > +bdrv_round_to_subclusters(BlockDriverState *bs, int64_t offset, int64_t bytes, > + int64_t *align_offset, int64_t *align_bytes) > { > BlockDriverInfo bdi; > IO_CODE(); > - if (bdrv_co_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) { > - *cluster_offset = offset; > - *cluster_bytes = bytes; > + if (bdrv_co_get_info(bs, &bdi) < 0 || bdi.subcluster_size == 0) { > + *align_offset = offset; > + *align_bytes = bytes; > } else { > - int64_t c = bdi.cluster_size; > - *cluster_offset = QEMU_ALIGN_DOWN(offset, c); > - *cluster_bytes = QEMU_ALIGN_UP(offset - *cluster_offset + bytes, c); > + int64_t c = bdi.subcluster_size; > + *align_offset = QEMU_ALIGN_DOWN(offset, c); > + *align_bytes = QEMU_ALIGN_UP(offset - *align_offset + bytes, c); > } > } > > @@ -1168,8 +1168,8 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, > void *bounce_buffer = NULL; > > BlockDriver *drv = bs->drv; > - int64_t cluster_offset; > - int64_t cluster_bytes; > + int64_t align_offset; > + int64_t align_bytes; > int64_t skip_bytes; > int ret; > int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, > @@ -1203,28 +1203,28 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, > * BDRV_REQUEST_MAX_BYTES (even when the original read did not), which > * is one reason we loop rather than doing it all at once. > */ > - bdrv_round_to_clusters(bs, offset, bytes, &cluster_offset, &cluster_bytes); > - skip_bytes = offset - cluster_offset; > + bdrv_round_to_subclusters(bs, offset, bytes, &align_offset, &align_bytes); > + skip_bytes = offset - align_offset; > > trace_bdrv_co_do_copy_on_readv(bs, offset, bytes, > - cluster_offset, cluster_bytes); > + align_offset, align_bytes); > > - while (cluster_bytes) { > + while (align_bytes) { > int64_t pnum; > > if (skip_write) { > ret = 1; /* "already allocated", so nothing will be copied */ > - pnum = MIN(cluster_bytes, max_transfer); > + pnum = MIN(align_bytes, max_transfer); > } else { > - ret = bdrv_is_allocated(bs, cluster_offset, > - MIN(cluster_bytes, max_transfer), &pnum); > + ret = bdrv_is_allocated(bs, align_offset, > + MIN(align_bytes, max_transfer), &pnum); > if (ret < 0) { > /* > * Safe to treat errors in querying allocation as if > * unallocated; we'll probably fail again soon on the > * read, but at least that will set a decent errno. > */ > - pnum = MIN(cluster_bytes, max_transfer); > + pnum = MIN(align_bytes, max_transfer); > } > > /* Stop at EOF if the image ends in the middle of the cluster */ > @@ -1242,7 +1242,7 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, > /* Must copy-on-read; use the bounce buffer */ > pnum = MIN(pnum, MAX_BOUNCE_BUFFER); > if (!bounce_buffer) { > - int64_t max_we_need = MAX(pnum, cluster_bytes - pnum); > + int64_t max_we_need = MAX(pnum, align_bytes - pnum); > int64_t max_allowed = MIN(max_transfer, MAX_BOUNCE_BUFFER); > int64_t bounce_buffer_len = MIN(max_we_need, max_allowed); > > @@ -1254,7 +1254,7 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, > } > qemu_iovec_init_buf(&local_qiov, bounce_buffer, pnum); > > - ret = bdrv_driver_preadv(bs, cluster_offset, pnum, > + ret = bdrv_driver_preadv(bs, align_offset, pnum, > &local_qiov, 0, 0); > if (ret < 0) { > goto err; > @@ -1266,13 +1266,13 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, > /* FIXME: Should we (perhaps conditionally) be setting > * BDRV_REQ_MAY_UNMAP, if it will allow for a sparser copy > * that still correctly reads as zero? */ > - ret = bdrv_co_do_pwrite_zeroes(bs, cluster_offset, pnum, > + ret = bdrv_co_do_pwrite_zeroes(bs, align_offset, pnum, > BDRV_REQ_WRITE_UNCHANGED); > } else { > /* This does not change the data on the disk, it is not > * necessary to flush even in cache=writethrough mode. > */ > - ret = bdrv_driver_pwritev(bs, cluster_offset, pnum, > + ret = bdrv_driver_pwritev(bs, align_offset, pnum, > &local_qiov, 0, > BDRV_REQ_WRITE_UNCHANGED); > } > @@ -1301,8 +1301,8 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, > } > } > > - cluster_offset += pnum; > - cluster_bytes -= pnum; > + align_offset += pnum; > + align_bytes -= pnum; > progress += pnum - skip_bytes; > skip_bytes = 0; > } > diff --git a/block/mirror.c b/block/mirror.c > index d3cacd1708..e213a892db 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -283,8 +283,8 @@ static int coroutine_fn mirror_cow_align(MirrorBlockJob *s, int64_t *offset, > need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, > s->cow_bitmap); > if (need_cow) { > - bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, > - &align_offset, &align_bytes); > + bdrv_round_to_subclusters(blk_bs(s->target), *offset, *bytes, > + &align_offset, &align_bytes); > } > > if (align_bytes > max_bytes) { > @@ -576,8 +576,8 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob *s) > int64_t target_offset; > int64_t target_bytes; > WITH_GRAPH_RDLOCK_GUARD() { > - bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, > - &target_offset, &target_bytes); > + bdrv_round_to_subclusters(blk_bs(s->target), offset, io_bytes, > + &target_offset, &target_bytes); > } > if (target_offset == offset && > target_bytes == io_bytes) { > diff --git a/include/block/block-io.h b/include/block/block-io.h > index 43af816d75..1311bec5e2 100644 > --- a/include/block/block-io.h > +++ b/include/block/block-io.h > @@ -189,7 +189,7 @@ bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi); > ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, > Error **errp); > BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs); > -void bdrv_round_to_clusters(BlockDriverState *bs, > +void bdrv_round_to_subclusters(BlockDriverState *bs, > int64_t offset, int64_t bytes, > int64_t *cluster_offset, > int64_t *cluster_bytes); Reviewed-by: Denis V. Lunev <den@openvz.org>
On 7/10/23 22:47, Eric Blake wrote: > On Mon, Jun 26, 2023 at 07:08:33PM +0300, Andrey Drobyshev via wrote: >> When target image is using subclusters, and we align the request during >> copy-on-read, it makes sense to align to subcluster_size rather than >> cluster_size. Otherwise we end up with unnecessary allocations. >> >> This commit renames bdrv_round_to_clusters() to bdrv_round_to_subclusters() >> and utilizes subcluster_size field of BlockDriverInfo to make necessary >> alignments. It affects copy-on-read as well as mirror job (which is >> using bdrv_round_to_clusters()). >> >> This change also fixes the following bug with failing assert (covered by >> the test in the subsequent commit): >> >> qemu-img create -f qcow2 base.qcow2 64K >> qemu-img create -f qcow2 -o extended_l2=on,backing_file=base.qcow2,backing_fmt=qcow2 img.qcow2 64K >> qemu-io -c "write -P 0xaa 0 2K" img.qcow2 >> qemu-io -C -c "read -P 0x00 2K 62K" img.qcow2 >> >> qemu-io: ../block/io.c:1236: bdrv_co_do_copy_on_readv: Assertion `skip_bytes < pnum' failed. >> >> Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> >> --- >> block/io.c | 50 ++++++++++++++++++++-------------------- >> block/mirror.c | 8 +++---- >> include/block/block-io.h | 2 +- >> 3 files changed, 30 insertions(+), 30 deletions(-) >> >> +++ b/include/block/block-io.h >> @@ -189,7 +189,7 @@ bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi); >> ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, >> Error **errp); >> BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs); >> -void bdrv_round_to_clusters(BlockDriverState *bs, >> +void bdrv_round_to_subclusters(BlockDriverState *bs, >> int64_t offset, int64_t bytes, >> int64_t *cluster_offset, >> int64_t *cluster_bytes); > > Indentation on subsequent lines should be fixed. Thanks for pointing that out, got it fixed in v2: https://lists.nongnu.org/archive/html/qemu-block/2023-07/msg00182.html > > Reviewed-by: Eric Blake <eblake@redhat.com> > > -- > Eric Blake, Principal Software Engineer > Red Hat, Inc. +1-919-301-3266 > Virtualization: qemu.org | libvirt.org >
diff --git a/block/io.c b/block/io.c index 30748f0b59..f1f8fad409 100644 --- a/block/io.c +++ b/block/io.c @@ -728,21 +728,21 @@ BdrvTrackedRequest *coroutine_fn bdrv_co_get_self_request(BlockDriverState *bs) } /** - * Round a region to cluster boundaries + * Round a region to subcluster (if supported) or cluster boundaries */ void coroutine_fn GRAPH_RDLOCK -bdrv_round_to_clusters(BlockDriverState *bs, int64_t offset, int64_t bytes, - int64_t *cluster_offset, int64_t *cluster_bytes) +bdrv_round_to_subclusters(BlockDriverState *bs, int64_t offset, int64_t bytes, + int64_t *align_offset, int64_t *align_bytes) { BlockDriverInfo bdi; IO_CODE(); - if (bdrv_co_get_info(bs, &bdi) < 0 || bdi.cluster_size == 0) { - *cluster_offset = offset; - *cluster_bytes = bytes; + if (bdrv_co_get_info(bs, &bdi) < 0 || bdi.subcluster_size == 0) { + *align_offset = offset; + *align_bytes = bytes; } else { - int64_t c = bdi.cluster_size; - *cluster_offset = QEMU_ALIGN_DOWN(offset, c); - *cluster_bytes = QEMU_ALIGN_UP(offset - *cluster_offset + bytes, c); + int64_t c = bdi.subcluster_size; + *align_offset = QEMU_ALIGN_DOWN(offset, c); + *align_bytes = QEMU_ALIGN_UP(offset - *align_offset + bytes, c); } } @@ -1168,8 +1168,8 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, void *bounce_buffer = NULL; BlockDriver *drv = bs->drv; - int64_t cluster_offset; - int64_t cluster_bytes; + int64_t align_offset; + int64_t align_bytes; int64_t skip_bytes; int ret; int max_transfer = MIN_NON_ZERO(bs->bl.max_transfer, @@ -1203,28 +1203,28 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, * BDRV_REQUEST_MAX_BYTES (even when the original read did not), which * is one reason we loop rather than doing it all at once. */ - bdrv_round_to_clusters(bs, offset, bytes, &cluster_offset, &cluster_bytes); - skip_bytes = offset - cluster_offset; + bdrv_round_to_subclusters(bs, offset, bytes, &align_offset, &align_bytes); + skip_bytes = offset - align_offset; trace_bdrv_co_do_copy_on_readv(bs, offset, bytes, - cluster_offset, cluster_bytes); + align_offset, align_bytes); - while (cluster_bytes) { + while (align_bytes) { int64_t pnum; if (skip_write) { ret = 1; /* "already allocated", so nothing will be copied */ - pnum = MIN(cluster_bytes, max_transfer); + pnum = MIN(align_bytes, max_transfer); } else { - ret = bdrv_is_allocated(bs, cluster_offset, - MIN(cluster_bytes, max_transfer), &pnum); + ret = bdrv_is_allocated(bs, align_offset, + MIN(align_bytes, max_transfer), &pnum); if (ret < 0) { /* * Safe to treat errors in querying allocation as if * unallocated; we'll probably fail again soon on the * read, but at least that will set a decent errno. */ - pnum = MIN(cluster_bytes, max_transfer); + pnum = MIN(align_bytes, max_transfer); } /* Stop at EOF if the image ends in the middle of the cluster */ @@ -1242,7 +1242,7 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, /* Must copy-on-read; use the bounce buffer */ pnum = MIN(pnum, MAX_BOUNCE_BUFFER); if (!bounce_buffer) { - int64_t max_we_need = MAX(pnum, cluster_bytes - pnum); + int64_t max_we_need = MAX(pnum, align_bytes - pnum); int64_t max_allowed = MIN(max_transfer, MAX_BOUNCE_BUFFER); int64_t bounce_buffer_len = MIN(max_we_need, max_allowed); @@ -1254,7 +1254,7 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, } qemu_iovec_init_buf(&local_qiov, bounce_buffer, pnum); - ret = bdrv_driver_preadv(bs, cluster_offset, pnum, + ret = bdrv_driver_preadv(bs, align_offset, pnum, &local_qiov, 0, 0); if (ret < 0) { goto err; @@ -1266,13 +1266,13 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, /* FIXME: Should we (perhaps conditionally) be setting * BDRV_REQ_MAY_UNMAP, if it will allow for a sparser copy * that still correctly reads as zero? */ - ret = bdrv_co_do_pwrite_zeroes(bs, cluster_offset, pnum, + ret = bdrv_co_do_pwrite_zeroes(bs, align_offset, pnum, BDRV_REQ_WRITE_UNCHANGED); } else { /* This does not change the data on the disk, it is not * necessary to flush even in cache=writethrough mode. */ - ret = bdrv_driver_pwritev(bs, cluster_offset, pnum, + ret = bdrv_driver_pwritev(bs, align_offset, pnum, &local_qiov, 0, BDRV_REQ_WRITE_UNCHANGED); } @@ -1301,8 +1301,8 @@ bdrv_co_do_copy_on_readv(BdrvChild *child, int64_t offset, int64_t bytes, } } - cluster_offset += pnum; - cluster_bytes -= pnum; + align_offset += pnum; + align_bytes -= pnum; progress += pnum - skip_bytes; skip_bytes = 0; } diff --git a/block/mirror.c b/block/mirror.c index d3cacd1708..e213a892db 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -283,8 +283,8 @@ static int coroutine_fn mirror_cow_align(MirrorBlockJob *s, int64_t *offset, need_cow |= !test_bit((*offset + *bytes - 1) / s->granularity, s->cow_bitmap); if (need_cow) { - bdrv_round_to_clusters(blk_bs(s->target), *offset, *bytes, - &align_offset, &align_bytes); + bdrv_round_to_subclusters(blk_bs(s->target), *offset, *bytes, + &align_offset, &align_bytes); } if (align_bytes > max_bytes) { @@ -576,8 +576,8 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob *s) int64_t target_offset; int64_t target_bytes; WITH_GRAPH_RDLOCK_GUARD() { - bdrv_round_to_clusters(blk_bs(s->target), offset, io_bytes, - &target_offset, &target_bytes); + bdrv_round_to_subclusters(blk_bs(s->target), offset, io_bytes, + &target_offset, &target_bytes); } if (target_offset == offset && target_bytes == io_bytes) { diff --git a/include/block/block-io.h b/include/block/block-io.h index 43af816d75..1311bec5e2 100644 --- a/include/block/block-io.h +++ b/include/block/block-io.h @@ -189,7 +189,7 @@ bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi); ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs, Error **errp); BlockStatsSpecific *bdrv_get_specific_stats(BlockDriverState *bs); -void bdrv_round_to_clusters(BlockDriverState *bs, +void bdrv_round_to_subclusters(BlockDriverState *bs, int64_t offset, int64_t bytes, int64_t *cluster_offset, int64_t *cluster_bytes);
When target image is using subclusters, and we align the request during copy-on-read, it makes sense to align to subcluster_size rather than cluster_size. Otherwise we end up with unnecessary allocations. This commit renames bdrv_round_to_clusters() to bdrv_round_to_subclusters() and utilizes subcluster_size field of BlockDriverInfo to make necessary alignments. It affects copy-on-read as well as mirror job (which is using bdrv_round_to_clusters()). This change also fixes the following bug with failing assert (covered by the test in the subsequent commit): qemu-img create -f qcow2 base.qcow2 64K qemu-img create -f qcow2 -o extended_l2=on,backing_file=base.qcow2,backing_fmt=qcow2 img.qcow2 64K qemu-io -c "write -P 0xaa 0 2K" img.qcow2 qemu-io -C -c "read -P 0x00 2K 62K" img.qcow2 qemu-io: ../block/io.c:1236: bdrv_co_do_copy_on_readv: Assertion `skip_bytes < pnum' failed. Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com> --- block/io.c | 50 ++++++++++++++++++++-------------------- block/mirror.c | 8 +++---- include/block/block-io.h | 2 +- 3 files changed, 30 insertions(+), 30 deletions(-)