qcow2: Reduce number of I/O requests
If the first part of a write request is allocated, but the second isn't
and it can be allocated so that the resulting area is contiguous, handle
it at once. This is a common case for sequential writes.
After this patch, alloc_cluster_offset() only checks if the clusters are
already allocated or how many new clusters can be allocated contigouosly.
The actual cluster allocation is split off into a new function
do_alloc_cluster_offset().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/trace-events b/trace-events
index d818ff1..606d903 100644
--- a/trace-events
+++ b/trace-events
@@ -320,6 +320,7 @@
qcow2_writev_data(void *co, uint64_t offset) "co %p offset %" PRIx64
qcow2_alloc_clusters_offset(void *co, uint64_t offset, int n_start, int n_end) "co %p offet %" PRIx64 " n_start %d n_end %d"
+qcow2_do_alloc_clusters_offset(void *co, uint64_t guest_offset, uint64_t host_offset, int nb_clusters) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " nb_clusters %d"
qcow2_cluster_alloc_phys(void *co) "co %p"
qcow2_cluster_link_l2(void *co, int nb_clusters) "co %p nb_clusters %d"
