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[Qemu-devel] [PULL 41/53] block/qcow2: Simplify shared L2 handling in am
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PULL 41/53] block/qcow2: Simplify shared L2 handling in amend |
Date: |
Mon, 3 Nov 2014 11:50:44 +0000 |
From: Max Reitz <address@hidden>
Currently, we have a bitmap for keeping track of which clusters have
been created during the zero cluster expansion process. This was
necessary because we need to properly increase the refcount for shared
L2 tables.
However, now we can simply take the L2 refcount and use it for the
cluster allocated for expansion. This will be the correct refcount and
therefore we don't have to remember that cluster having been allocated
any more.
Signed-off-by: Max Reitz <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
Reviewed-by: BenoƮt Canet <address@hidden>
Reviewed-by: Kevin Wolf <address@hidden>
Reviewed-by: Benoit Canet <address@hidden>
Message-id: address@hidden
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
block/qcow2-cluster.c | 94 +++++++++++++++------------------------------------
1 file changed, 28 insertions(+), 66 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 5687a4b..df0b2c9 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1613,20 +1613,12 @@ fail:
* Expands all zero clusters in a specific L1 table (or deallocates them, for
* non-backed non-pre-allocated zero clusters).
*
- * expanded_clusters is a bitmap where every bit corresponds to one cluster in
- * the image file; a bit gets set if the corresponding cluster has been used
for
- * zero expansion (i.e., has been filled with zeroes and is referenced from an
- * L2 table). nb_clusters contains the total cluster count of the image file,
- * i.e., the number of bits in expanded_clusters.
- *
* l1_entries and *visited_l1_entries are used to keep track of progress for
* status_cb(). l1_entries contains the total number of L1 entries and
* *visited_l1_entries counts all visited L1 entries.
*/
static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
- int l1_size, uint8_t **expanded_clusters,
- uint64_t *nb_clusters,
- int64_t *visited_l1_entries,
+ int l1_size, int64_t *visited_l1_entries,
int64_t l1_entries,
BlockDriverAmendStatusCB *status_cb)
{
@@ -1648,6 +1640,7 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
for (i = 0; i < l1_size; i++) {
uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
bool l2_dirty = false;
+ int l2_refcount;
if (!l2_offset) {
/* unallocated */
@@ -1671,33 +1664,19 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
goto fail;
}
+ l2_refcount = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits);
+ if (l2_refcount < 0) {
+ ret = l2_refcount;
+ goto fail;
+ }
+
for (j = 0; j < s->l2_size; j++) {
uint64_t l2_entry = be64_to_cpu(l2_table[j]);
- int64_t offset = l2_entry & L2E_OFFSET_MASK, cluster_index;
+ int64_t offset = l2_entry & L2E_OFFSET_MASK;
int cluster_type = qcow2_get_cluster_type(l2_entry);
bool preallocated = offset != 0;
- if (cluster_type == QCOW2_CLUSTER_NORMAL) {
- cluster_index = offset >> s->cluster_bits;
- assert((cluster_index >= 0) && (cluster_index < *nb_clusters));
- if ((*expanded_clusters)[cluster_index / 8] &
- (1 << (cluster_index % 8))) {
- /* Probably a shared L2 table; this cluster was a zero
- * cluster which has been expanded, its refcount
- * therefore most likely requires an update. */
- ret = qcow2_update_cluster_refcount(bs, cluster_index, 1,
- QCOW2_DISCARD_NEVER);
- if (ret < 0) {
- goto fail;
- }
- /* Since we just increased the refcount, the COPIED flag
may
- * no longer be set. */
- l2_table[j] = cpu_to_be64(l2_entry & ~QCOW_OFLAG_COPIED);
- l2_dirty = true;
- }
- continue;
- }
- else if (qcow2_get_cluster_type(l2_entry) != QCOW2_CLUSTER_ZERO) {
+ if (cluster_type != QCOW2_CLUSTER_ZERO) {
continue;
}
@@ -1715,6 +1694,19 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
ret = offset;
goto fail;
}
+
+ if (l2_refcount > 1) {
+ /* For shared L2 tables, set the refcount accordingly (it
is
+ * already 1 and needs to be l2_refcount) */
+ ret = qcow2_update_cluster_refcount(bs,
+ offset >> s->cluster_bits, l2_refcount - 1,
+ QCOW2_DISCARD_OTHER);
+ if (ret < 0) {
+ qcow2_free_clusters(bs, offset, s->cluster_size,
+ QCOW2_DISCARD_OTHER);
+ goto fail;
+ }
+ }
}
ret = qcow2_pre_write_overlap_check(bs, 0, offset,
s->cluster_size);
@@ -1736,29 +1728,12 @@ static int expand_zero_clusters_in_l1(BlockDriverState
*bs, uint64_t *l1_table,
goto fail;
}
- l2_table[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED);
- l2_dirty = true;
-
- cluster_index = offset >> s->cluster_bits;
-
- if (cluster_index >= *nb_clusters) {
- uint64_t old_bitmap_size = (*nb_clusters + 7) / 8;
- uint64_t new_bitmap_size;
- /* The offset may lie beyond the old end of the underlying
image
- * file for growable files only */
- assert(bs->file->growable);
- *nb_clusters = size_to_clusters(s, bs->file->total_sectors *
- BDRV_SECTOR_SIZE);
- new_bitmap_size = (*nb_clusters + 7) / 8;
- *expanded_clusters = g_realloc(*expanded_clusters,
- new_bitmap_size);
- /* clear the newly allocated space */
- memset(&(*expanded_clusters)[old_bitmap_size], 0,
- new_bitmap_size - old_bitmap_size);
+ if (l2_refcount == 1) {
+ l2_table[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED);
+ } else {
+ l2_table[j] = cpu_to_be64(offset);
}
-
- assert((cluster_index >= 0) && (cluster_index < *nb_clusters));
- (*expanded_clusters)[cluster_index / 8] |= 1 << (cluster_index %
8);
+ l2_dirty = true;
}
if (is_active_l1) {
@@ -1823,9 +1798,7 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs,
{
BDRVQcowState *s = bs->opaque;
uint64_t *l1_table = NULL;
- uint64_t nb_clusters;
int64_t l1_entries = 0, visited_l1_entries = 0;
- uint8_t *expanded_clusters;
int ret;
int i, j;
@@ -1836,16 +1809,7 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs,
}
}
- nb_clusters = size_to_clusters(s, bs->file->total_sectors *
- BDRV_SECTOR_SIZE);
- expanded_clusters = g_try_malloc0((nb_clusters + 7) / 8);
- if (expanded_clusters == NULL) {
- ret = -ENOMEM;
- goto fail;
- }
-
ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size,
- &expanded_clusters, &nb_clusters,
&visited_l1_entries, l1_entries,
status_cb);
if (ret < 0) {
@@ -1881,7 +1845,6 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs,
}
ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size,
- &expanded_clusters, &nb_clusters,
&visited_l1_entries, l1_entries,
status_cb);
if (ret < 0) {
@@ -1892,7 +1855,6 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs,
ret = 0;
fail:
- g_free(expanded_clusters);
g_free(l1_table);
return ret;
}
--
1.9.3
- [Qemu-devel] [PULL 31/53] qemu-img: Specify backing file for commit, (continued)
- [Qemu-devel] [PULL 31/53] qemu-img: Specify backing file for commit, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 32/53] iotests: Add _filter_qemu_img_map, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 33/53] iotests: Add test for backing-chain commits, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 34/53] iotests: Add test for qcow2's bdrv_make_empty, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 36/53] block: Add status callback to bdrv_amend_options(), Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 35/53] block: qemu-iotest 107 supports NFS, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 37/53] qemu-img: Add progress output for amend, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 38/53] qemu-img: Fix insignificant memleak, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 39/53] block/qcow2: Implement status CB for amend, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 40/53] block/qcow2: Make get_refcount() global, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 41/53] block/qcow2: Simplify shared L2 handling in amend,
Stefan Hajnoczi <=
- [Qemu-devel] [PULL 42/53] iotests: Expand test 061, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 43/53] block: acquire AioContext in generic blockjob QMP commands, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 44/53] blockdev: acquire AioContext in do_qmp_query_block_jobs_one(), Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 45/53] blockdev: acquire AioContext in blockdev_mark_auto_del(), Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 46/53] blockdev: add note that block_job_cb() must be thread-safe, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 47/53] blockjob: add block_job_defer_to_main_loop(), Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 48/53] block: add bdrv_drain(), Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 49/53] block: let backup blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 50/53] block: let stream blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/11/03
- [Qemu-devel] [PULL 52/53] block: let commit blockjob run in BDS AioContext, Stefan Hajnoczi, 2014/11/03