From: Alberto Garcia <berto@igalia.com>
To: qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
Alberto Garcia <berto@igalia.com>,
qemu-block@nongnu.org, Derek Su <dereksu@qnap.com>,
Max Reitz <mreitz@redhat.com>
Subject: [PATCH v7 23/32] qcow2: Add subcluster support to discard_in_l2_slice()
Date: Mon, 25 May 2020 20:08:48 +0200 [thread overview]
Message-ID: <9df951fae42d4ee19104913315835c033b28e14f.1590429901.git.berto@igalia.com> (raw)
In-Reply-To: <cover.1590429901.git.berto@igalia.com>
Two things need to be taken into account here:
1) With full_discard == true the L2 entry must be cleared completely.
This also includes the L2 bitmap if the image has extended L2
entries.
2) With full_discard == false we have to make the discarded cluster
read back as zeroes. With normal L2 entries this is done with the
QCOW_OFLAG_ZERO bit, whereas with extended L2 entries this is done
with the individual 'all zeroes' bits for each subcluster.
Note however that QCOW_OFLAG_ZERO is not supported in v2 qcow2
images so, if there is a backing file, discard cannot guarantee
that the image will read back as zeroes. If this is important for
the caller it should forbid it as qcow2_co_pdiscard() does (see
80f5c01183 for more details).
Signed-off-by: Alberto Garcia <berto@igalia.com>
---
block/qcow2-cluster.c | 52 +++++++++++++++++++------------------------
1 file changed, 23 insertions(+), 29 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 4e59bbd545..edfc8ea91c 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1847,11 +1847,17 @@ static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset,
assert(nb_clusters <= INT_MAX);
for (i = 0; i < nb_clusters; i++) {
- uint64_t old_l2_entry;
-
- old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
+ uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
+ uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
+ uint64_t new_l2_entry = old_l2_entry;
+ uint64_t new_l2_bitmap = old_l2_bitmap;
+ QCow2ClusterType cluster_type =
+ qcow2_get_cluster_type(bs, old_l2_entry);
/*
+ * If full_discard is true, the cluster should not read back as zeroes,
+ * but rather fall through to the backing file.
+ *
* If full_discard is false, make sure that a discarded area reads back
* as zeroes for v3 images (we cannot do it for v2 without actually
* writing a zero-filled buffer). We can skip the operation if the
@@ -1860,40 +1866,28 @@ static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset,
*
* TODO We might want to use bdrv_block_status(bs) here, but we're
* holding s->lock, so that doesn't work today.
- *
- * If full_discard is true, the sector should not read back as zeroes,
- * but rather fall through to the backing file.
*/
- switch (qcow2_get_cluster_type(bs, old_l2_entry)) {
- case QCOW2_CLUSTER_UNALLOCATED:
- if (full_discard || !bs->backing) {
- continue;
+ if (full_discard) {
+ new_l2_entry = new_l2_bitmap = 0;
+ } else if (bs->backing || qcow2_cluster_is_allocated(cluster_type)) {
+ if (has_subclusters(s)) {
+ new_l2_entry = 0;
+ new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES;
+ } else {
+ new_l2_entry = s->qcow_version >= 3 ? QCOW_OFLAG_ZERO : 0;
}
- break;
+ }
- case QCOW2_CLUSTER_ZERO_PLAIN:
- if (!full_discard) {
- continue;
- }
- break;
-
- case QCOW2_CLUSTER_ZERO_ALLOC:
- case QCOW2_CLUSTER_NORMAL:
- case QCOW2_CLUSTER_COMPRESSED:
- break;
-
- default:
- abort();
+ if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) {
+ continue;
}
/* First remove L2 entries */
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
- if (!full_discard && s->qcow_version >= 3) {
- set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_ZERO);
- } else {
- set_l2_entry(s, l2_slice, l2_index + i, 0);
+ set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry);
+ if (has_subclusters(s)) {
+ set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap);
}
-
/* Then decrease the refcount */
qcow2_free_any_clusters(bs, old_l2_entry, 1, type);
}
--
2.20.1
next prev parent reply other threads:[~2020-05-25 18:13 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-25 18:08 [PATCH v7 00/32] Add subcluster allocation to qcow2 Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 01/32] qcow2: Make Qcow2AioTask store the full host offset Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 02/32] qcow2: Convert qcow2_get_cluster_offset() into qcow2_get_host_offset() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 03/32] qcow2: Add calculate_l2_meta() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 04/32] qcow2: Split cluster_needs_cow() out of count_cow_clusters() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 05/32] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 06/32] qcow2: Add get_l2_entry() and set_l2_entry() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 07/32] qcow2: Document the Extended L2 Entries feature Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 08/32] qcow2: Add dummy has_subclusters() function Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 09/32] qcow2: Add subcluster-related fields to BDRVQcow2State Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 10/32] qcow2: Add offset_to_sc_index() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 11/32] qcow2: Add offset_into_subcluster() and size_to_subclusters() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 12/32] qcow2: Add l2_entry_size() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 13/32] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 14/32] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type() Alberto Garcia
2020-05-26 20:32 ` Eric Blake
2020-05-27 9:51 ` Alberto Garcia
2020-05-27 13:27 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 15/32] qcow2: Add qcow2_get_subcluster_range_type() Alberto Garcia
2020-05-26 21:48 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 16/32] qcow2: Add qcow2_cluster_is_allocated() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 17/32] qcow2: Add cluster type parameter to qcow2_get_host_offset() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 18/32] qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_* Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 19/32] qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 20/32] qcow2: Add subcluster support to calculate_l2_meta() Alberto Garcia
2020-05-27 15:57 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 21/32] qcow2: Add subcluster support to qcow2_get_host_offset() Alberto Garcia
2020-05-27 16:40 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 22/32] qcow2: Add subcluster support to zero_in_l2_slice() Alberto Garcia
2020-05-27 16:43 ` Eric Blake
2020-05-25 18:08 ` Alberto Garcia [this message]
2020-05-27 16:50 ` [PATCH v7 23/32] qcow2: Add subcluster support to discard_in_l2_slice() Eric Blake
2020-05-25 18:08 ` [PATCH v7 24/32] qcow2: Add subcluster support to check_refcounts_l2() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 25/32] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2() Alberto Garcia
2020-05-27 16:52 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 26/32] qcow2: Clear the L2 bitmap when allocating a compressed cluster Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 27/32] qcow2: Add subcluster support to handle_alloc_space() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 28/32] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes() Alberto Garcia
2020-05-27 17:58 ` Eric Blake
2020-05-28 15:04 ` Alberto Garcia
2020-05-28 19:11 ` Eric Blake
2020-05-29 16:06 ` Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 29/32] qcow2: Add subcluster support to qcow2_measure() Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 30/32] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit Alberto Garcia
2020-05-27 18:03 ` Eric Blake
2020-05-25 18:08 ` [PATCH v7 31/32] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters Alberto Garcia
2020-05-25 18:08 ` [PATCH v7 32/32] iotests: Add tests for qcow2 images with extended L2 entries Alberto Garcia
2020-05-27 18:30 ` Eric Blake
2020-05-29 15:07 ` Alberto Garcia
2020-05-29 15:13 ` Eric Blake
2020-05-26 2:54 ` [PATCH v7 00/32] Add subcluster allocation to qcow2 no-reply
2020-05-26 11:01 ` Alberto Garcia
2020-05-26 5:17 ` no-reply
2020-05-26 5:48 ` no-reply
2020-05-26 6:14 ` no-reply
2020-05-26 8:01 ` no-reply
2020-05-26 10:13 ` no-reply
2020-05-26 13:08 ` no-reply
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