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 424bedd..3e877a4 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -609,12 +609,12 @@ 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;
@@ -675,16 +675,22 @@ 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,
@@ -698,7 +704,7 @@ 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);
@@ -715,6 +721,7 @@ uint64_t qcow2_alloc_cluster_offset(BlockDriverState *bs,
cluster_offset = ~QCOW_OFLAG_COPIED;
m-nb_clusters = 0;
+m-depends_on = NULL;
goto out;
}
@@ -793,10 +800,11 @@ 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;
