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qcow2: Add refcount update reason to all callers

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This adds a refcount update reason to all callers of update_refcounts(),
so that a follow-up patch can use this information to decide whether
clusters that reach a refcount of 0 should be discarded in the image
file.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2013-06-19 13:44:18 +02:00 committed by Stefan Hajnoczi
parent 492fdc6fbe
commit 6cfcb9b8b9
5 changed files with 66 additions and 33 deletions
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19
block/qcow2-cluster.c
View File

@ -98,14 +98,16 @@ int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
goto fail;
}
g_free(s->l1_table);
qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t));
qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t),
QCOW2_DISCARD_OTHER);
s->l1_table_offset = new_l1_table_offset;
s->l1_table = new_l1_table;
s->l1_size = new_l1_size;
return 0;
fail:
g_free(new_l1_table);
qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2);
qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,
QCOW2_DISCARD_OTHER);
return ret;
}
@ -548,7 +550,8 @@ static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
/* Then decrease the refcount of the old table */
if (l2_offset) {
qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t));
qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
QCOW2_DISCARD_OTHER);
}
}
@ -715,10 +718,14 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
/*
* If this was a COW, we need to decrease the refcount of the old cluster.
* Also flush bs->file to get the right order for L2 and refcount update.
*
* Don't discard clusters that reach a refcount of 0 (e.g. compressed
* clusters), the next write will reuse them anyway.
*/
if (j != 0) {
for (i = 0; i < j; i++) {
qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1);
qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
QCOW2_DISCARD_NEVER);
}
}
@ -1339,7 +1346,7 @@ static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
l2_table[l2_index + i] = cpu_to_be64(0);
/* Then decrease the refcount */
qcow2_free_any_clusters(bs, old_offset, 1);
qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
}
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
@ -1415,7 +1422,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
if (old_offset & QCOW_OFLAG_COMPRESSED) {
l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
qcow2_free_any_clusters(bs, old_offset, 1);
qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
} else {
l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
}

55
block/qcow2-refcount.c
View File

@ -29,7 +29,7 @@
static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size);
static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
int64_t offset, int64_t length,
int addend);
int addend, enum qcow2_discard_type type);
/*********************************************************/
@ -235,7 +235,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
} else {
/* Described somewhere else. This can recurse at most twice before we
* arrive at a block that describes itself. */
ret = update_refcount(bs, new_block, s->cluster_size, 1);
ret = update_refcount(bs, new_block, s->cluster_size, 1,
QCOW2_DISCARD_NEVER);
if (ret < 0) {
goto fail_block;
}
@ -399,7 +400,8 @@ static int alloc_refcount_block(BlockDriverState *bs,
/* Free old table. Remember, we must not change free_cluster_index */
uint64_t old_free_cluster_index = s->free_cluster_index;
qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t));
qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t),
QCOW2_DISCARD_OTHER);
s->free_cluster_index = old_free_cluster_index;
ret = load_refcount_block(bs, new_block, (void**) refcount_block);
@ -420,7 +422,7 @@ fail_block:
/* XXX: cache several refcount block clusters ? */
static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
int64_t offset, int64_t length, int addend)
int64_t offset, int64_t length, int addend, enum qcow2_discard_type type)
{
BDRVQcowState *s = bs->opaque;
int64_t start, last, cluster_offset;
@ -506,7 +508,8 @@ fail:
*/
if (ret < 0) {
int dummy;
dummy = update_refcount(bs, offset, cluster_offset - offset, -addend);
dummy = update_refcount(bs, offset, cluster_offset - offset, -addend,
QCOW2_DISCARD_NEVER);
(void)dummy;
}
@ -522,12 +525,14 @@ fail:
*/
static int update_cluster_refcount(BlockDriverState *bs,
int64_t cluster_index,
int addend)
int addend,
enum qcow2_discard_type type)
{
BDRVQcowState *s = bs->opaque;
int ret;
ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend);
ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend,
type);
if (ret < 0) {
return ret;
}
@ -579,7 +584,7 @@ int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size)
return offset;
}
ret = update_refcount(bs, offset, size, 1);
ret = update_refcount(bs, offset, size, 1, QCOW2_DISCARD_NEVER);
if (ret < 0) {
return ret;
}
@ -611,7 +616,8 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
old_free_cluster_index = s->free_cluster_index;
s->free_cluster_index = cluster_index + i;
ret = update_refcount(bs, offset, i << s->cluster_bits, 1);
ret = update_refcount(bs, offset, i << s->cluster_bits, 1,
QCOW2_DISCARD_NEVER);
if (ret < 0) {
return ret;
}
@ -649,7 +655,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
if (free_in_cluster == 0)
s->free_byte_offset = 0;
if ((offset & (s->cluster_size - 1)) != 0)
update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
QCOW2_DISCARD_NEVER);
} else {
offset = qcow2_alloc_clusters(bs, s->cluster_size);
if (offset < 0) {
@ -659,7 +666,8 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
if ((cluster_offset + s->cluster_size) == offset) {
/* we are lucky: contiguous data */
offset = s->free_byte_offset;
update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
QCOW2_DISCARD_NEVER);
s->free_byte_offset += size;
} else {
s->free_byte_offset = offset;
@ -676,12 +684,13 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
}
void qcow2_free_clusters(BlockDriverState *bs,
int64_t offset, int64_t size)
int64_t offset, int64_t size,
enum qcow2_discard_type type)
{
int ret;
BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE);
ret = update_refcount(bs, offset, size, -1);
ret = update_refcount(bs, offset, size, -1, type);
if (ret < 0) {
fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret));
/* TODO Remember the clusters to free them later and avoid leaking */
@ -692,8 +701,8 @@ void qcow2_free_clusters(BlockDriverState *bs,
* Free a cluster using its L2 entry (handles clusters of all types, e.g.
* normal cluster, compressed cluster, etc.)
*/
void qcow2_free_any_clusters(BlockDriverState *bs,
uint64_t l2_entry, int nb_clusters)
void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
int nb_clusters, enum qcow2_discard_type type)
{
BDRVQcowState *s = bs->opaque;
@ -705,12 +714,12 @@ void qcow2_free_any_clusters(BlockDriverState *bs,
s->csize_mask) + 1;
qcow2_free_clusters(bs,
(l2_entry & s->cluster_offset_mask) & ~511,
nb_csectors * 512);
nb_csectors * 512, type);
}
break;
case QCOW2_CLUSTER_NORMAL:
qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK,
nb_clusters << s->cluster_bits);
nb_clusters << s->cluster_bits, type);
break;
case QCOW2_CLUSTER_UNALLOCATED:
case QCOW2_CLUSTER_ZERO:
@ -785,7 +794,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
int ret;
ret = update_refcount(bs,
(offset & s->cluster_offset_mask) & ~511,
nb_csectors * 512, addend);
nb_csectors * 512, addend,
QCOW2_DISCARD_SNAPSHOT);
if (ret < 0) {
goto fail;
}
@ -795,7 +805,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
} else {
uint64_t cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits;
if (addend != 0) {
refcount = update_cluster_refcount(bs, cluster_index, addend);
refcount = update_cluster_refcount(bs, cluster_index, addend,
QCOW2_DISCARD_SNAPSHOT);
} else {
refcount = get_refcount(bs, cluster_index);
}
@ -827,7 +838,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs,
if (addend != 0) {
refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend);
refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend,
QCOW2_DISCARD_SNAPSHOT);
} else {
refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
}
@ -1253,7 +1265,8 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
if (num_fixed) {
ret = update_refcount(bs, i << s->cluster_bits, 1,
refcount2 - refcount1);
refcount2 - refcount1,
QCOW2_DISCARD_ALWAYS);
if (ret >= 0) {
(*num_fixed)++;
continue;

6
block/qcow2-snapshot.c
View File

@ -262,7 +262,8 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
}
/* free the old snapshot table */
qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size,
QCOW2_DISCARD_SNAPSHOT);
s->snapshots_offset = snapshots_offset;
s->snapshots_size = snapshots_size;
return 0;
@ -569,7 +570,8 @@ int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
if (ret < 0) {
return ret;
}
qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t));
qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t),
QCOW2_DISCARD_SNAPSHOT);
/* must update the copied flag on the current cluster offsets */
ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);

3
block/qcow2.c
View File

@ -1196,7 +1196,8 @@ static int preallocate(BlockDriverState *bs)
ret = qcow2_alloc_cluster_link_l2(bs, meta);
if (ret < 0) {
qcow2_free_any_clusters(bs, meta->alloc_offset, meta->nb_clusters);
qcow2_free_any_clusters(bs, meta->alloc_offset, meta->nb_clusters,
QCOW2_DISCARD_NEVER);
return ret;
}

16
block/qcow2.h
View File

@ -129,6 +129,15 @@ enum {
QCOW2_COMPAT_FEAT_MASK = QCOW2_COMPAT_LAZY_REFCOUNTS,
};
enum qcow2_discard_type {
QCOW2_DISCARD_NEVER = 0,
QCOW2_DISCARD_ALWAYS,
QCOW2_DISCARD_REQUEST,
QCOW2_DISCARD_SNAPSHOT,
QCOW2_DISCARD_OTHER,
QCOW2_DISCARD_MAX
};
typedef struct Qcow2Feature {
uint8_t type;
uint8_t bit;
@ -349,9 +358,10 @@ int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
int nb_clusters);
int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size);
void qcow2_free_clusters(BlockDriverState *bs,
int64_t offset, int64_t size);
void qcow2_free_any_clusters(BlockDriverState *bs,
uint64_t cluster_offset, int nb_clusters);
int64_t offset, int64_t size,
enum qcow2_discard_type type);
void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
int nb_clusters, enum qcow2_discard_type type);
int qcow2_update_snapshot_refcount(BlockDriverState *bs,
int64_t l1_table_offset, int l1_size, int addend);