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[Qemu-block] [PATCH v4 17/39] qcow2: Update l2_allocate() to support L2
From: |
Alberto Garcia |
Subject: |
[Qemu-block] [PATCH v4 17/39] qcow2: Update l2_allocate() to support L2 slices |
Date: |
Mon, 5 Feb 2018 16:33:17 +0200 |
This patch updates l2_allocate() to support the qcow2 cache returning
L2 slices instead of full L2 tables.
The old code simply gets an L2 table from the cache and initializes it
with zeroes or with the contents of an existing table. With a cache
that returns slices instead of tables the idea remains the same, but
the code must now iterate over all the slices that are contained in an
L2 table.
Since now we're operating with slices the function can no longer
return the newly-allocated table, so it's up to the caller to retrieve
the appropriate L2 slice after calling l2_allocate() (note that with
this patch the caller is still loading full L2 tables, but we'll deal
with that in a separate patch).
Signed-off-by: Alberto Garcia <address@hidden>
Reviewed-by: Eric Blake <address@hidden>
---
block/qcow2-cluster.c | 56 +++++++++++++++++++++++++++++++--------------------
1 file changed, 34 insertions(+), 22 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 57349928a9..e0a3802161 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -264,11 +264,12 @@ int qcow2_write_l1_entry(BlockDriverState *bs, int
l1_index)
*
*/
-static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
+static int l2_allocate(BlockDriverState *bs, int l1_index)
{
BDRVQcow2State *s = bs->opaque;
uint64_t old_l2_offset;
- uint64_t *l2_table = NULL;
+ uint64_t *l2_slice = NULL;
+ unsigned slice, slice_size2, n_slices;
int64_t l2_offset;
int ret;
@@ -299,42 +300,45 @@ static int l2_allocate(BlockDriverState *bs, int
l1_index, uint64_t **table)
/* allocate a new entry in the l2 cache */
+ slice_size2 = s->l2_slice_size * sizeof(uint64_t);
+ n_slices = s->cluster_size / slice_size2;
+
trace_qcow2_l2_allocate_get_empty(bs, l1_index);
- {
+ for (slice = 0; slice < n_slices; slice++) {
ret = qcow2_cache_get_empty(bs, s->l2_table_cache,
- l2_offset,
- (void **) table);
+ l2_offset + slice * slice_size2,
+ (void **) &l2_slice);
if (ret < 0) {
goto fail;
}
- l2_table = *table;
-
if ((old_l2_offset & L1E_OFFSET_MASK) == 0) {
- /* if there was no old l2 table, clear the new table */
- memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
+ /* if there was no old l2 table, clear the new slice */
+ memset(l2_slice, 0, slice_size2);
} else {
- uint64_t *old_table;
+ uint64_t *old_slice;
+ uint64_t old_l2_slice_offset =
+ (old_l2_offset & L1E_OFFSET_MASK) + slice * slice_size2;
- /* if there was an old l2 table, read it from the disk */
+ /* if there was an old l2 table, read a slice from the disk */
BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
- ret = qcow2_cache_get(bs, s->l2_table_cache,
- old_l2_offset & L1E_OFFSET_MASK,
- (void **) &old_table);
+ ret = qcow2_cache_get(bs, s->l2_table_cache, old_l2_slice_offset,
+ (void **) &old_slice);
if (ret < 0) {
goto fail;
}
- memcpy(l2_table, old_table, s->cluster_size);
+ memcpy(l2_slice, old_slice, slice_size2);
- qcow2_cache_put(s->l2_table_cache, (void **) &old_table);
+ qcow2_cache_put(s->l2_table_cache, (void **) &old_slice);
}
- /* write the l2 table to the file */
+ /* write the l2 slice to the file */
BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE);
trace_qcow2_l2_allocate_write_l2(bs, l1_index);
- qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
+ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
+ qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
}
ret = qcow2_cache_flush(bs, s->l2_table_cache);
@@ -350,14 +354,13 @@ static int l2_allocate(BlockDriverState *bs, int
l1_index, uint64_t **table)
goto fail;
}
- *table = l2_table;
trace_qcow2_l2_allocate_done(bs, l1_index, 0);
return 0;
fail:
trace_qcow2_l2_allocate_done(bs, l1_index, ret);
- if (l2_table != NULL) {
- qcow2_cache_put(s->l2_table_cache, (void **) table);
+ if (l2_slice != NULL) {
+ qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
}
s->l1_table[l1_index] = old_l2_offset;
if (l2_offset > 0) {
@@ -702,7 +705,7 @@ static int get_cluster_table(BlockDriverState *bs, uint64_t
offset,
}
} else {
/* First allocate a new L2 table (and do COW if needed) */
- ret = l2_allocate(bs, l1_index, &l2_table);
+ ret = l2_allocate(bs, l1_index);
if (ret < 0) {
return ret;
}
@@ -712,6 +715,15 @@ static int get_cluster_table(BlockDriverState *bs,
uint64_t offset,
qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
QCOW2_DISCARD_OTHER);
}
+
+ /* Get the offset of the newly-allocated l2 table */
+ l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
+ assert(offset_into_cluster(s, l2_offset) == 0);
+ /* Load the l2 table in memory */
+ ret = l2_load(bs, offset, l2_offset, &l2_table);
+ if (ret < 0) {
+ return ret;
+ }
}
/* find the cluster offset for the given disk offset */
--
2.11.0
- [Qemu-block] [PATCH v4 00/39] Allow configuring the qcow2 L2 cache entry size, Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 05/39] qcow2: Remove BDS parameter from qcow2_cache_table_release(), Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 04/39] qcow2: Remove BDS parameter from qcow2_cache_get_table_idx(), Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 08/39] qcow2: Remove BDS parameter from qcow2_cache_destroy(), Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 17/39] qcow2: Update l2_allocate() to support L2 slices,
Alberto Garcia <=
- [Qemu-block] [PATCH v4 07/39] qcow2: Remove BDS parameter from qcow2_cache_put(), Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 10/39] qcow2: Remove BDS parameter from qcow2_cache_discard(), Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 06/39] qcow2: Remove BDS parameter from qcow2_cache_entry_mark_dirty(), Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 24/39] qcow2: Update discard_single_l2() to support L2 slices, Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 35/39] qcow2: Rename l2_table in count_cow_clusters(), Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 15/39] qcow2: Update l2_load() to support L2 slices, Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 20/39] qcow2: Update qcow2_get_cluster_offset() to support L2 slices, Alberto Garcia, 2018/02/05
- [Qemu-block] [PATCH v4 13/39] qcow2: Add l2_slice_size field to BDRVQcow2State, Alberto Garcia, 2018/02/05