file-posix: Mitigate file fragmentation with extent size hints

[qemu.git] / include / block / block_int.h

diff --git a/include/block/block_int.h b/include/block/block_int.h
index 791de6a59c2c0ca7dac10b754ca9f266edf01b07..38dec0275be19a6ab55e34ba41a2f1aa0537f24a 100644 (file)
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -53,6 +53,7 @@
 #define BLOCK_OPT_ADAPTER_TYPE      "adapter_type"
 #define BLOCK_OPT_REDUNDANCY        "redundancy"
 #define BLOCK_OPT_NOCOW             "nocow"
+#define BLOCK_OPT_EXTENT_SIZE_HINT  "extent_size_hint"
 #define BLOCK_OPT_OBJECT_SIZE       "object_size"
 #define BLOCK_OPT_REFCOUNT_BITS     "refcount_bits"
 #define BLOCK_OPT_DATA_FILE         "data_file"
@@ -123,7 +124,17 @@ struct BlockDriver {
      */
     bool bdrv_needs_filename;
 
-    /* Set if a driver can support backing files */
+    /*
+     * Set if a driver can support backing files. This also implies the
+     * following semantics:
+     *
+     *  - Return status 0 of .bdrv_co_block_status means that corresponding
+     *    blocks are not allocated in this layer of backing-chain
+     *  - For such (unallocated) blocks, read will:
+     *    - fill buffer with zeros if there is no backing file
+     *    - read from the backing file otherwise, where the block layer
+     *      takes care of reading zeros beyond EOF if backing file is short
+     */
     bool supports_backing;
 
     /* For handling image reopen for split or non-split files */
@@ -141,12 +152,27 @@ struct BlockDriver {
     int (*bdrv_file_open)(BlockDriverState *bs, QDict *options, int flags,
                           Error **errp);
     void (*bdrv_close)(BlockDriverState *bs);
+
+
     int coroutine_fn (*bdrv_co_create)(BlockdevCreateOptions *opts,
                                        Error **errp);
     int coroutine_fn (*bdrv_co_create_opts)(BlockDriver *drv,
                                             const char *filename,
                                             QemuOpts *opts,
                                             Error **errp);
+
+    int coroutine_fn (*bdrv_co_amend)(BlockDriverState *bs,
+                                      BlockdevAmendOptions *opts,
+                                      bool force,
+                                      Error **errp);
+
+    int (*bdrv_amend_options)(BlockDriverState *bs,
+                              QemuOpts *opts,
+                              BlockDriverAmendStatusCB *status_cb,
+                              void *cb_opaque,
+                              bool force,
+                              Error **errp);
+
     int (*bdrv_make_empty)(BlockDriverState *bs);
 
     /*
@@ -420,6 +446,10 @@ struct BlockDriver {
 
     /* List of options for creating images, terminated by name == NULL */
     QemuOptsList *create_opts;
+
+    /* List of options for image amend */
+    QemuOptsList *amend_opts;
+
     /*
      * If this driver supports reopening images this contains a
      * NULL-terminated list of the runtime options that can be
@@ -437,11 +467,6 @@ struct BlockDriver {
                                       BdrvCheckResult *result,
                                       BdrvCheckMode fix);
 
-    int (*bdrv_amend_options)(BlockDriverState *bs, QemuOpts *opts,
-                              BlockDriverAmendStatusCB *status_cb,
-                              void *cb_opaque,
-                              Error **errp);
-
     void (*bdrv_debug_event)(BlockDriverState *bs, BlkdebugEvent event);
 
     /* TODO Better pass a option string/QDict/QemuOpts to add any rule? */