[PATCH v2 5/6] block/block-copy: add memory limit

[Vladimir Sementsov-Ogievskiy]

Currently total allocation for parallel requests to block-copy instance
is unlimited. Let's limit it to 128 MiB.

For now block-copy is used only in backup, so actually we limit total
allocation for backup job.

Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 include/block/block-copy.h | 3 +++
 block/block-copy.c         | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/include/block/block-copy.h b/include/block/block-copy.h
index e2e135ff1b..edcdf0072d 100644
--- a/include/block/block-copy.h
+++ b/include/block/block-copy.h
@@ -16,6 +16,7 @@
 #define BLOCK_COPY_H
 
 #include "block/block.h"
+#include "qemu/co-shared-resource.h"
 
 typedef struct BlockCopyInFlightReq {
     int64_t start_byte;
@@ -69,6 +70,8 @@ typedef struct BlockCopyState {
      */
     ProgressResetCallbackFunc progress_reset_callback;
     void *progress_opaque;
+
+    SharedResource *mem;
 } BlockCopyState;
 
 BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
diff --git a/block/block-copy.c b/block/block-copy.c
index c21db48734..d5042e46fd 100644
--- a/block/block-copy.c
+++ b/block/block-copy.c
@@ -21,6 +21,7 @@
 #include "qemu/units.h"
 
 #define BLOCK_COPY_MAX_COPY_RANGE (16 * MiB)
+#define BLOCK_COPY_MAX_MEM (128 * MiB)
 
 static void coroutine_fn block_copy_wait_inflight_reqs(BlockCopyState *s,
                                                        int64_t start,
@@ -64,6 +65,7 @@ void block_copy_state_free(BlockCopyState *s)
     }
 
     bdrv_release_dirty_bitmap(s->source->bs, s->copy_bitmap);
+    shres_destroy(s->mem);
     g_free(s);
 }
 
@@ -95,6 +97,7 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, 
BdrvChild *target,
         .cluster_size = cluster_size,
         .len = bdrv_dirty_bitmap_size(copy_bitmap),
         .write_flags = write_flags,
+        .mem = shres_create(BLOCK_COPY_MAX_MEM),
     };
 
     s->copy_range_size = QEMU_ALIGN_DOWN(max_transfer, cluster_size),
@@ -313,7 +316,9 @@ int coroutine_fn block_copy(BlockCopyState *s,
 
         bdrv_reset_dirty_bitmap(s->copy_bitmap, start, chunk_end - start);
 
+        co_get_from_shres(s->mem, chunk_end - start);
         ret = block_copy_do_copy(s, start, chunk_end, error_is_read);
+        co_put_to_shres(s->mem, chunk_end - start);
         if (ret < 0) {
             bdrv_set_dirty_bitmap(s->copy_bitmap, start, chunk_end - start);
             break;
-- 
2.21.0