| Message ID | 8f366482d2b273c26ff67cba1de898289f613fc7.1572125022.git.berto@igalia.com |
|---|---|
| State | New |
| Headers | show |
| Series | Add subcluster allocation to qcow2 | expand |
On 26.10.19 23:25, Alberto Garcia wrote: > Setting the QCOW_OFLAG_ZERO bit of the L2 entry is forbidden if an > image has subclusters. Instead, the individual 'all zeroes' bits must > be used. > > Signed-off-by: Alberto Garcia <berto@igalia.com> > --- > block/qcow2-cluster.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c > index e67559152f..3e4ba8d448 100644 > --- a/block/qcow2-cluster.c > +++ b/block/qcow2-cluster.c > @@ -1852,7 +1852,7 @@ static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset, > assert(nb_clusters <= INT_MAX); > > for (i = 0; i < nb_clusters; i++) { > - uint64_t old_offset; > + uint64_t old_offset, l2_entry = 0; > QCow2ClusterType cluster_type; > > old_offset = get_l2_entry(s, l2_slice, l2_index + i); > @@ -1869,12 +1869,18 @@ static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset, > > qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); > if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) { > - set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_ZERO); > qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST); It feels wrong to me to free the cluster before updating the L2 entry. Max > } else { > - uint64_t entry = get_l2_entry(s, l2_slice, l2_index + i); > - set_l2_entry(s, l2_slice, l2_index + i, entry | QCOW_OFLAG_ZERO); > + l2_entry = get_l2_entry(s, l2_slice, l2_index + i); > } > + > + if (has_subclusters(s)) { > + set_l2_bitmap(s, l2_slice, l2_index + i, QCOW_L2_BITMAP_ALL_ZEROES); > + } else { > + l2_entry |= QCOW_OFLAG_ZERO; > + } > + > + set_l2_entry(s, l2_slice, l2_index + i, l2_entry); > } > > qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); >
On 04.11.19 16:04, Max Reitz wrote: > On 26.10.19 23:25, Alberto Garcia wrote: >> Setting the QCOW_OFLAG_ZERO bit of the L2 entry is forbidden if an >> image has subclusters. Instead, the individual 'all zeroes' bits must >> be used. >> >> Signed-off-by: Alberto Garcia <berto@igalia.com> >> --- >> block/qcow2-cluster.c | 14 ++++++++++---- >> 1 file changed, 10 insertions(+), 4 deletions(-) >> >> diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c >> index e67559152f..3e4ba8d448 100644 >> --- a/block/qcow2-cluster.c >> +++ b/block/qcow2-cluster.c >> @@ -1852,7 +1852,7 @@ static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset, >> assert(nb_clusters <= INT_MAX); >> >> for (i = 0; i < nb_clusters; i++) { >> - uint64_t old_offset; >> + uint64_t old_offset, l2_entry = 0; >> QCow2ClusterType cluster_type; >> >> old_offset = get_l2_entry(s, l2_slice, l2_index + i); >> @@ -1869,12 +1869,18 @@ static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset, >> >> qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); >> if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) { >> - set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_ZERO); >> qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST); > > It feels wrong to me to free the cluster before updating the L2 entry. (Although it’s pre-existing, as set_l2_entry() is just an in-cache operation anyway :-/) Max
On Mon 04 Nov 2019 04:10:58 PM CET, Max Reitz wrote: >>> qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); >>> if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) { >>> - set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_ZERO); >>> qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST); >> >> It feels wrong to me to free the cluster before updating the L2 >> entry. > > (Although it’s pre-existing, as set_l2_entry() is just an in-cache > operation anyway :-/) Yes, I think that if you want to do it afterwards you need to add another loop after the qcow2_cache_put() call. Berto
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index e67559152f..3e4ba8d448 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1852,7 +1852,7 @@ static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset, assert(nb_clusters <= INT_MAX); for (i = 0; i < nb_clusters; i++) { - uint64_t old_offset; + uint64_t old_offset, l2_entry = 0; QCow2ClusterType cluster_type; old_offset = get_l2_entry(s, l2_slice, l2_index + i); @@ -1869,12 +1869,18 @@ static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset, qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) { - set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_ZERO); qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST); } else { - uint64_t entry = get_l2_entry(s, l2_slice, l2_index + i); - set_l2_entry(s, l2_slice, l2_index + i, entry | QCOW_OFLAG_ZERO); + l2_entry = get_l2_entry(s, l2_slice, l2_index + i); } + + if (has_subclusters(s)) { + set_l2_bitmap(s, l2_slice, l2_index + i, QCOW_L2_BITMAP_ALL_ZEROES); + } else { + l2_entry |= QCOW_OFLAG_ZERO; + } + + set_l2_entry(s, l2_slice, l2_index + i, l2_entry); } qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
Setting the QCOW_OFLAG_ZERO bit of the L2 entry is forbidden if an image has subclusters. Instead, the individual 'all zeroes' bits must be used. Signed-off-by: Alberto Garcia <berto@igalia.com> --- block/qcow2-cluster.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)