Returning 0/-errno allows it to distingush different errors classes. The
cluster offset of newly allocated clusters is now returned in the QCowL2Meta
struct.
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
block/qcow2-cluster.c | 28 ++++++++++++++++++----------
block/qcow2.c | 36 +++++++++++++++++++-----------------
block/qcow2.h | 4 ++--
3 files changed, 39 insertions(+), 29 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index dec0af6..d23d5b3 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -611,12 +611,12 @@ static int write_l2_entries(BDRVQcowState *s, uint64_t
*l2_table,
return 0;
}
-int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, uint64_t cluster_offset,
- QCowL2Meta *m)
+int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
{
BDRVQcowState *s = bs->opaque;
int i, j = 0, l2_index, ret;
uint64_t *old_cluster, start_sect, l2_offset, *l2_table;
+ uint64_t cluster_offset = m->cluster_offset;
if (m->nb_clusters == 0)
return 0;
@@ -677,16 +677,22 @@ err:
/*
* alloc_cluster_offset
*
- * For a given offset of the disk image, return cluster offset in
- * qcow2 file.
- *
+ * For a given offset of the disk image, return cluster offset in qcow2 file.
* If the offset is not found, allocate a new cluster.
*
- * Return the cluster offset if successful,
- * Return 0, otherwise.
+ * If the cluster was already allocated, m->nb_clusters is set to 0,
+ * m->depends_on is set to NULL and the other fields in m are meaningless.
+ *
+ * If the cluster is newly allocated, m->nb_clusters is set to the number of
+ * contiguous clusters that have been allocated. This may be 0 if the request
+ * conflict with another write request in flight; in this case, m->depends_on
+ * is set and the remaining fields of m are meaningless.
*
+ * If m->nb_clusters is non-zero, the other fields of m are valid and contain
+ * information about the first allocated cluster.
+ *
+ * Return 0 on success and -errno in error cases
*/
-
uint64_t qcow2_alloc_cluster_offset(BlockDriverState *bs,
uint64_t offset,
int n_start, int n_end,
@@ -700,7 +706,7 @@ uint64_t qcow2_alloc_cluster_offset(BlockDriverState *bs,
ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
if (ret < 0) {
- return 0;
+ return ret;
}
nb_clusters = size_to_clusters(s, n_end << 9);
@@ -717,6 +723,7 @@ uint64_t qcow2_alloc_cluster_offset(BlockDriverState *bs,
cluster_offset &= ~QCOW_OFLAG_COPIED;
m->nb_clusters = 0;
+ m->depends_on = NULL;
goto out;
}
@@ -795,10 +802,11 @@ uint64_t qcow2_alloc_cluster_offset(BlockDriverState *bs,
out:
m->nb_available = MIN(nb_clusters << (s->cluster_bits - 9), n_end);
+ m->cluster_offset = cluster_offset;
*num = m->nb_available - n_start;
- return cluster_offset;
+ return 0;
}
static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
diff --git a/block/qcow2.c b/block/qcow2.c
index e06f4dd..773d381 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -561,7 +561,7 @@ static void qcow_aio_write_cb(void *opaque, int ret)
acb->hd_aiocb = NULL;
if (ret >= 0) {
- ret = qcow2_alloc_cluster_link_l2(bs, acb->cluster_offset,
&acb->l2meta);
+ ret = qcow2_alloc_cluster_link_l2(bs, &acb->l2meta);
}
run_dependent_requests(&acb->l2meta);
@@ -585,21 +585,23 @@ static void qcow_aio_write_cb(void *opaque, int ret)
n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors)
n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
- acb->cluster_offset = qcow2_alloc_cluster_offset(bs, acb->sector_num << 9,
- index_in_cluster,
- n_end, &acb->n, &acb->l2meta);
+ ret = qcow2_alloc_cluster_offset(bs, acb->sector_num << 9,
+ index_in_cluster, n_end, &acb->n, &acb->l2meta);
+ if (ret < 0) {
+ goto done;
+ }
+
+ acb->cluster_offset = acb->l2meta.cluster_offset;
/* Need to wait for another request? If so, we are done for now. */
- if (!acb->cluster_offset && acb->l2meta.depends_on != NULL) {
+ if (acb->l2meta.nb_clusters == 0 && acb->l2meta.depends_on != NULL) {
QLIST_INSERT_HEAD(&acb->l2meta.depends_on->dependent_requests,
acb, next_depend);
return;
}
- if (!acb->cluster_offset || (acb->cluster_offset & 511) != 0) {
- ret = -EIO;
- goto done;
- }
+ assert((acb->cluster_offset & 511) == 0);
+
if (s->crypt_method) {
if (!acb->cluster_data) {
acb->cluster_data = qemu_mallocz(QCOW_MAX_CRYPT_CLUSTERS *
@@ -782,27 +784,27 @@ static int get_bits_from_size(size_t size)
static int preallocate(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
- uint64_t cluster_offset = 0;
uint64_t nb_sectors;
uint64_t offset;
int num;
+ int ret;
QCowL2Meta meta;
nb_sectors = bdrv_getlength(bs) >> 9;
offset = 0;
QLIST_INIT(&meta.dependent_requests);
+ meta.cluster_offset = 0;
while (nb_sectors) {
num = MIN(nb_sectors, INT_MAX >> 9);
- cluster_offset = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num,
- &meta);
+ ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num, &meta);
- if (cluster_offset == 0) {
+ if (ret < 0) {
return -1;
}
- if (qcow2_alloc_cluster_link_l2(bs, cluster_offset, &meta) < 0) {
- qcow2_free_any_clusters(bs, cluster_offset, meta.nb_clusters);
+ if (qcow2_alloc_cluster_link_l2(bs, &meta) < 0) {
+ qcow2_free_any_clusters(bs, meta.cluster_offset, meta.nb_clusters);
return -1;
}
@@ -821,10 +823,10 @@ static int preallocate(BlockDriverState *bs)
* all of the allocated clusters (otherwise we get failing reads after
* EOF). Extend the image to the last allocated sector.
*/
- if (cluster_offset != 0) {
+ if (meta.cluster_offset != 0) {
uint8_t buf[512];
memset(buf, 0, 512);
- bdrv_write(s->hd, (cluster_offset >> 9) + num - 1, buf, 1);
+ bdrv_write(s->hd, (meta.cluster_offset >> 9) + num - 1, buf, 1);
}
return 0;
diff --git a/block/qcow2.h b/block/qcow2.h
index 26ab5d9..d9ea6ab 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -135,6 +135,7 @@ struct QCowAIOCB;
typedef struct QCowL2Meta
{
uint64_t offset;
+ uint64_t cluster_offset;
int n_start;
int nb_available;
int nb_clusters;
@@ -199,8 +200,7 @@ uint64_t
qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
uint64_t offset,
int compressed_size);
-int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, uint64_t cluster_offset,
- QCowL2Meta *m);
+int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
/* qcow2-snapshot.c functions */
int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info);
--
1.6.5.2
