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[Qemu-devel] [PATCH 40/43] qcow2: Allocate l2meta only for cluster alloc
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 40/43] qcow2: Allocate l2meta only for cluster allocations |
Date: |
Thu, 13 Dec 2012 16:10:47 +0100 |
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 66ca12f..08d92cc 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -787,8 +787,7 @@ 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);
@@ -799,7 +798,7 @@ 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;
}
@@ -845,14 +844,16 @@ 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;
@@ -1134,11 +1135,10 @@ 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);
@@ -1148,15 +1148,17 @@ 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] [PATCH 31/43] blkdebug: Implement suspend/resume of AIO requests, (continued)
- [Qemu-devel] [PATCH 31/43] blkdebug: Implement suspend/resume of AIO requests, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 20/43] qemu-io: Implement write -c for compressed clusters, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 26/43] introduce qemu_opts_create_nofail function, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 29/43] blkdebug: Allow usage without config file, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 15/43] qemu-img: img_create(): drop unneeded goto and ret variable, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 21/43] rbd: Fix race between aio completition and aio cancel, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 19/43] tests: Add tests for fdsets, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 24/43] qemu-option: qemu_opts_validate(): fix duplicated code, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 42/43] qcow2: Execute run_dependent_requests() without lock, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 38/43] qcow2: Allocate l2meta dynamically, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 40/43] qcow2: Allocate l2meta only for cluster allocations,
Kevin Wolf <=
- [Qemu-devel] [PATCH 36/43] qcow2: Round QCowL2Meta.offset down to cluster boundary, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 34/43] qemu-iotests: Test concurrent cluster allocations, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 37/43] qcow2: Introduce Qcow2COWRegion, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 25/43] qemu-option: qemu_opt_set_bool(): fix code duplication, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 18/43] block: bdrv_img_create(): drop unused error handling code, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 32/43] qemu-io: Add AIO debugging commands, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 28/43] create new function: qemu_opt_set_number, Kevin Wolf, 2012/12/13
- [Qemu-devel] [PATCH 23/43] qemu-option: opt_set(): split it up into more functions, Kevin Wolf, 2012/12/13