Introduce Qcow2 runtime boolean option "discard-subclusters". This
option influences discard alignment value (either cluster_size or
subcluster_size) and essentially makes subcluster-based discard optional.
We disable it by default.
Also tweak iotests/271 to enable this option and really test subcluster
based discards.
Signed-off-by: Andrey Drobyshev <andrey.drobys...@virtuozzo.com>
---
block/qcow2.c | 21 ++++++++++++++++++++-
block/qcow2.h | 2 ++
tests/qemu-iotests/271 | 10 ++++++----
3 files changed, 28 insertions(+), 5 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index c2086d0bd1..7c38a5be41 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -685,6 +685,7 @@ static const char *const mutable_opts[] = {
QCOW2_OPT_DISCARD_SNAPSHOT,
QCOW2_OPT_DISCARD_OTHER,
QCOW2_OPT_DISCARD_NO_UNREF,
+ QCOW2_OPT_DISCARD_SUBCLUSTERS,
QCOW2_OPT_OVERLAP,
QCOW2_OPT_OVERLAP_TEMPLATE,
QCOW2_OPT_OVERLAP_MAIN_HEADER,
@@ -734,6 +735,11 @@ static QemuOptsList qcow2_runtime_opts = {
.type = QEMU_OPT_BOOL,
.help = "Do not unreference discarded clusters",
},
+ {
+ .name = QCOW2_OPT_DISCARD_SUBCLUSTERS,
+ .type = QEMU_OPT_BOOL,
+ .help = "Allow subcluster aligned discard requests",
+ },
{
.name = QCOW2_OPT_OVERLAP,
.type = QEMU_OPT_STRING,
@@ -978,6 +984,7 @@ typedef struct Qcow2ReopenState {
int overlap_check;
bool discard_passthrough[QCOW2_DISCARD_MAX];
bool discard_no_unref;
+ bool discard_subclusters;
uint64_t cache_clean_interval;
QCryptoBlockOpenOptions *crypto_opts; /* Disk encryption runtime options */
} Qcow2ReopenState;
@@ -1157,6 +1164,16 @@ qcow2_update_options_prepare(BlockDriverState *bs,
Qcow2ReopenState *r,
goto fail;
}
+ r->discard_subclusters =
+ qemu_opt_get_bool(opts, QCOW2_OPT_DISCARD_SUBCLUSTERS, false);
+ if (r->discard_subclusters && !has_subclusters(s)) {
+ error_setg(errp,
+ "Image doesn't have extended L2 entries, but option "
+ "'discard-subclusters' is enabled");
+ ret = -EINVAL;
+ goto fail;
+ }
+
switch (s->crypt_method_header) {
case QCOW_CRYPT_NONE:
if (encryptfmt) {
@@ -1238,6 +1255,7 @@ static void qcow2_update_options_commit(BlockDriverState
*bs,
}
s->discard_no_unref = r->discard_no_unref;
+ s->discard_subclusters = r->discard_subclusters;
if (s->cache_clean_interval != r->cache_clean_interval) {
cache_clean_timer_del(bs);
@@ -1981,7 +1999,8 @@ static void qcow2_refresh_limits(BlockDriverState *bs,
Error **errp)
bs->bl.request_alignment = qcrypto_block_get_sector_size(s->crypto);
}
bs->bl.pwrite_zeroes_alignment = s->subcluster_size;
- bs->bl.pdiscard_alignment = s->subcluster_size;
+ bs->bl.pdiscard_alignment = s->discard_subclusters ?
+ s->subcluster_size : s->cluster_size;
}
static int GRAPH_UNLOCKED
diff --git a/block/qcow2.h b/block/qcow2.h
index a65c185b51..4e91bdde3f 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -134,6 +134,7 @@
#define QCOW2_OPT_DISCARD_SNAPSHOT "pass-discard-snapshot"
#define QCOW2_OPT_DISCARD_OTHER "pass-discard-other"
#define QCOW2_OPT_DISCARD_NO_UNREF "discard-no-unref"
+#define QCOW2_OPT_DISCARD_SUBCLUSTERS "discard-subclusters"
#define QCOW2_OPT_OVERLAP "overlap-check"
#define QCOW2_OPT_OVERLAP_TEMPLATE "overlap-check.template"
#define QCOW2_OPT_OVERLAP_MAIN_HEADER "overlap-check.main-header"
@@ -387,6 +388,7 @@ typedef struct BDRVQcow2State {
bool discard_passthrough[QCOW2_DISCARD_MAX];
bool discard_no_unref;
+ bool discard_subclusters;
int overlap_check; /* bitmask of Qcow2MetadataOverlap values */
bool signaled_corruption;
diff --git a/tests/qemu-iotests/271 b/tests/qemu-iotests/271
index 8b80682cff..d7cf3c459b 100755
--- a/tests/qemu-iotests/271
+++ b/tests/qemu-iotests/271
@@ -100,13 +100,14 @@ _filter_trace_fallocate()
# discard -> discard
_run_test()
{
- unset c sc off len cmd opt
+ unset c sc off len cmd trace opt
for var in "$@"; do eval "$var"; done
case "${cmd:-write}" in
zero)
cmd="write -q -z";;
unmap)
- opt="--trace enable=file_do_fallocate"
+ trace="--trace enable=file_do_fallocate"
+ opt="-c reopen -o discard-subclusters=on"
cmd="write -q -z -u";;
compress)
pat=$((${pat:-0} + 1))
@@ -115,7 +116,8 @@ _run_test()
pat=$((${pat:-0} + 1))
cmd="write -q -P ${pat}";;
discard)
- opt="--trace enable=file_do_fallocate"
+ trace="--trace enable=file_do_fallocate"
+ opt="-c reopen -o discard-subclusters=on"
cmd="discard -q";;
*)
echo "Unknown option $cmd"
@@ -129,7 +131,7 @@ _run_test()
cmd="$cmd ${offset} ${len}"
raw_cmd=$(echo $cmd | sed s/-c//) # Raw images don't support -c
echo $cmd | sed 's/-P [0-9][0-9]\?/-P PATTERN/'
- $QEMU_IO $opt -c "$cmd" "$TEST_IMG" 2>&1 | _filter_qemu_io |
_filter_trace_fallocate
+ $QEMU_IO $trace ${opt:+ "$opt"} -c "$cmd" "$TEST_IMG" 2>&1 |
_filter_qemu_io | _filter_trace_fallocate
$QEMU_IO -c "$raw_cmd" -f raw "$TEST_IMG.raw" | _filter_qemu_io
_verify_img
_verify_l2_bitmap "$c"
--
2.39.3
