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[Qemu-devel] [RFC PATCH 05/16] qcow2: Allocate l2meta only for cluster a
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [RFC PATCH 05/16] qcow2: Allocate l2meta only for cluster allocations |
Date: |
Tue, 18 Sep 2012 13:40:31 +0200 |
Even for writes to already allocated clusters, an l2meta is allocated,
though it stays effectively unused. After this patch, only allocating
requests still have one. Each l2meta now describes an in-flight request
that writes to clusters that are not yet hooked up in the L2 table.
Signed-off-by: Kevin Wolf <address@hidden>
---
block/qcow2-cluster.c | 23 +++++++++--------------
block/qcow2.c | 32 +++++++++++++++++---------------
block/qcow2.h | 7 +++++--
3 files changed, 31 insertions(+), 31 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index c4752ee..c2b59e7 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -652,9 +652,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs,
QCowL2Meta *m)
uint64_t cluster_offset = m->alloc_offset;
trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
-
- if (m->nb_clusters == 0)
- return 0;
+ assert(m->nb_clusters > 0);
old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
@@ -856,7 +854,7 @@ static int do_alloc_cluster_offset(BlockDriverState *bs,
uint64_t guest_offset,
* Return 0 on success and -errno in error cases
*/
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
- int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta *m)
+ int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m)
{
BDRVQcowState *s = bs->opaque;
int l2_index, ret, sectors;
@@ -928,11 +926,6 @@ again:
}
/* If there is something left to allocate, do that now */
- *m = (QCowL2Meta) {
- .nb_clusters = 0,
- };
- qemu_co_queue_init(&m->dependent_requests);
-
if (nb_clusters > 0) {
uint64_t alloc_offset;
uint64_t alloc_cluster_offset;
@@ -980,7 +973,9 @@ again:
cluster_offset = alloc_cluster_offset;
}
- *m = (QCowL2Meta) {
+ *m = g_malloc0(sizeof(**m));
+
+ **m = (QCowL2Meta) {
.alloc_offset = alloc_cluster_offset,
.offset = alloc_offset & ~(s->cluster_size - 1),
.nb_clusters = nb_clusters,
@@ -995,8 +990,8 @@ again:
.nb_sectors = avail_sectors - nb_sectors,
},
};
- qemu_co_queue_init(&m->dependent_requests);
- QLIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight);
+ qemu_co_queue_init(&(*m)->dependent_requests);
+ QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
}
}
@@ -1013,8 +1008,8 @@ again:
return 0;
fail:
- if (m->nb_clusters > 0) {
- QLIST_REMOVE(m, next_in_flight);
+ if (*m && (*m)->nb_clusters > 0) {
+ QLIST_REMOVE(*m, next_in_flight);
}
return ret;
}
diff --git a/block/qcow2.c b/block/qcow2.c
index a98e899..c0a2822 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -778,8 +778,7 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState
*bs,
while (remaining_sectors != 0) {
- l2meta = g_malloc0(sizeof(*l2meta));
- qemu_co_queue_init(&l2meta->dependent_requests);
+ l2meta = NULL;
trace_qcow2_writev_start_part(qemu_coroutine_self());
index_in_cluster = sector_num & (s->cluster_sectors - 1);
@@ -790,7 +789,7 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState
*bs,
}
ret = qcow2_alloc_cluster_offset(bs, sector_num << 9,
- index_in_cluster, n_end, &cur_nr_sectors, &cluster_offset, l2meta);
+ index_in_cluster, n_end, &cur_nr_sectors, &cluster_offset,
&l2meta);
if (ret < 0) {
goto fail;
}
@@ -836,14 +835,16 @@ static coroutine_fn int qcow2_co_writev(BlockDriverState
*bs,
goto fail;
}
- ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
- if (ret < 0) {
- goto fail;
- }
+ if (l2meta != NULL) {
+ ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
+ if (ret < 0) {
+ goto fail;
+ }
- run_dependent_requests(s, l2meta);
- g_free(l2meta);
- l2meta = NULL;
+ run_dependent_requests(s, l2meta);
+ g_free(l2meta);
+ l2meta = NULL;
+ }
remaining_sectors -= cur_nr_sectors;
sector_num += cur_nr_sectors;
@@ -1124,11 +1125,10 @@ static int preallocate(BlockDriverState *bs)
uint64_t host_offset = 0;
int num;
int ret;
- QCowL2Meta meta;
+ QCowL2Meta *meta;
nb_sectors = bdrv_getlength(bs) >> 9;
offset = 0;
- qemu_co_queue_init(&meta.dependent_requests);
while (nb_sectors) {
num = MIN(nb_sectors, INT_MAX >> 9);
@@ -1138,15 +1138,17 @@ static int preallocate(BlockDriverState *bs)
return ret;
}
- ret = qcow2_alloc_cluster_link_l2(bs, &meta);
+ 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);
return ret;
}
/* There are no dependent requests, but we need to remove our request
* from the list of in-flight requests */
- run_dependent_requests(bs->opaque, &meta);
+ if (meta != NULL) {
+ run_dependent_requests(bs->opaque, meta);
+ }
/* TODO Preallocate data if requested */
diff --git a/block/qcow2.h b/block/qcow2.h
index 24f1001..6dc79b5 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -207,7 +207,10 @@ typedef struct Qcow2COWRegion {
int nb_sectors;
} Qcow2COWRegion;
-/* XXX This could be private for qcow2-cluster.c */
+/**
+ * Describes an in-flight (part of a) write request that writes to clusters
+ * that are not referenced in their L2 table yet.
+ */
typedef struct QCowL2Meta
{
/** Guest offset of the first newly allocated cluster */
@@ -333,7 +336,7 @@ void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t
sector_num,
int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
int *num, uint64_t *cluster_offset);
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
- int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta *m);
+ int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m);
uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
uint64_t offset,
int compressed_size);
--
1.7.6.5
- [Qemu-devel] [RFC PATCH 00/16] qcow2: Delayed COW, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 03/16] qcow2: Allocate l2meta dynamically, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 08/16] qcow2: Reading from areas not in L2 tables yet, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 16/16] [BROKEN] qcow2: Overwrite COW and allocate new cluster at the same time, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 02/16] qcow2: Introduce Qcow2COWRegion, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 01/16] qcow2: Round QCowL2Meta.offset down to cluster boundary, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 04/16] qcow2: Drop l2meta.cluster_offset, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 07/16] qcow2: Factor out handle_dependencies(), Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 06/16] qcow2: Enable dirty flag in qcow2_alloc_cluster_link_l2, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 05/16] qcow2: Allocate l2meta only for cluster allocations,
Kevin Wolf <=
- [Qemu-devel] [RFC PATCH 12/16] qcow2: Handle dependencies earlier, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 14/16] qcow2: Execute run_dependent_requests() without lock, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 09/16] qcow2: Move COW and L2 update into own coroutine, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 13/16] qcow2: Change handle_dependency to byte granularity, Kevin Wolf, 2012/09/18
- [Qemu-devel] [RFC PATCH 11/16] qcow2: Add error handling to the l2meta coroutine, Kevin Wolf, 2012/09/18