mirrors/qemu
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

qcow2: Don't hold cache references across yield

Browse Source 
If cache references are held while the coroutine has yielded, the cache
may get used up and abort() when it can't find a free entry.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2012-04-24 16:10:56 +02:00
parent 60651f901a
commit 7242411460
1 changed files with 13 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
block/qcow2-cluster.c
View File

@ -853,6 +853,7 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
n_start, n_end);
/* Find L2 entry for the first involved cluster */
again:
ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
if (ret < 0) {
return ret;
@ -862,7 +863,6 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
* Calculate the number of clusters to look for. We stop at L2 table
* boundaries to keep things simple.
*/
again:
nb_clusters = MIN(size_to_clusters(s, n_end << BDRV_SECTOR_BITS),
s->l2_size - l2_index);
@ -896,6 +896,18 @@ again:
cluster_offset &= L2E_OFFSET_MASK;
/*
* The L2 table isn't used any more after this. As long as the cache works
* synchronously, it's important to release it before calling
* do_alloc_cluster_offset, which may yield if we need to wait for another
* request to complete. If we still had the reference, we could use up the
* whole cache with sleeping requests.
*/
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
if (ret < 0) {
return ret;
}
/* If there is something left to allocate, do that now */
*m = (QCowL2Meta) {
.cluster_offset = cluster_offset,
@ -947,11 +959,6 @@ again:
}
/* Some cleanup work */
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
if (ret < 0) {
goto fail_put;
}
sectors = (keep_clusters + nb_clusters) << (s->cluster_bits - 9);
if (sectors > n_end) {
sectors = n_end;
@ -963,8 +970,6 @@ again:
return 0;
fail:
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
fail_put:
if (m->nb_clusters > 0) {
QLIST_REMOVE(m, next_in_flight);
}