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[Qemu-devel] [PATCH v3 17/39] qcow2: Update l2_allocate() to support L2
From: |
Alberto Garcia |
Subject: |
[Qemu-devel] [PATCH v3 17/39] qcow2: Update l2_allocate() to support L2 slices |
Date: |
Fri, 26 Jan 2018 16:59:44 +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>
---
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..2a53c1dc5f 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 an 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
- Re: [Qemu-devel] [PATCH v3 37/39] iotests: Test valid values of l2-cache-entry-size, (continued)
- [Qemu-devel] [PATCH v3 39/39] iotests: Add l2-cache-entry-size to iotest 137, Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 27/39] qcow2: Update qcow2_update_snapshot_refcount() to support L2 slices, Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 04/39] qcow2: Remove BDS parameter from qcow2_cache_get_table_idx(), Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 34/39] qcow2: Rename l2_table in count_contiguous_clusters_unallocated(), Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 01/39] qcow2: Fix documentation of get_cluster_table(), Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 17/39] qcow2: Update l2_allocate() to support L2 slices,
Alberto Garcia <=
- [Qemu-devel] [PATCH v3 20/39] qcow2: Update qcow2_get_cluster_offset() to support L2 slices, Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 32/39] qcow2: Rename l2_table in qcow2_alloc_compressed_cluster_offset(), Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 06/39] qcow2: Remove BDS parameter from qcow2_cache_entry_mark_dirty(), Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 38/39] iotests: Test downgrading an image using a small L2 slice size, Alberto Garcia, 2018/01/26
- [Qemu-devel] [PATCH v3 35/39] qcow2: Rename l2_table in count_cow_clusters(), Alberto Garcia, 2018/01/26