Add optional file ID for qemu drives

For testing multipath in systemd's integration tests, we need multiple
qemu drives backed by the same file. Let's allow specifying an additional
file ID to make this possible with QemuDrive=.

diff --git a/mkosi/config.py b/mkosi/config.py
index 759a54dc4c1b7133ed5dcd0aa5807964038086a5..100d006ca8c516504c0eade1156cc9714f2e4a26 100644 (file)
--- a/mkosi/config.py
+++ b/mkosi/config.py
@@ -138,6 +138,7 @@ class QemuDrive:
     size: int
     directory: Optional[Path]
     options: Optional[str]
+    file_id: str
 
 
 # We use negative numbers for specifying special constants
@@ -1051,7 +1052,7 @@ def parse_drive(value: str) -> QemuDrive:
     if len(parts) < 2:
         die(f"Missing size in drive '{value}")
 
-    if len(parts) > 4:
+    if len(parts) > 5:
         die(f"Too many components in drive '{value}")
 
     id = parts[0]
@@ -1062,8 +1063,9 @@ def parse_drive(value: str) -> QemuDrive:
 
     directory = parse_path(parts[2]) if len(parts) > 2 and parts[2] else None
     options = parts[3] if len(parts) > 3 and parts[3] else None
+    file_id = parts[4] if len(parts) > 4 and parts[4] else id
 
-    return QemuDrive(id=id, size=size, directory=directory, options=options)
+    return QemuDrive(id=id, size=size, directory=directory, options=options, file_id=file_id)
 
 
 def config_parse_sector_size(value: Optional[str], old: Optional[int]) -> Optional[int]:
@@ -4154,19 +4156,20 @@ def json_type_transformer(refcls: Union[type[Args], type[Config]]) -> Callable[[
     def config_drive_transformer(drives: list[dict[str, Any]], fieldtype: type[QemuDrive]) -> list[QemuDrive]:
         # TODO: exchange for TypeGuard and list comprehension once on 3.10
         ret = []
+
         for d in drives:
             assert "Id" in d
             assert "Size" in d
-            assert "Directory" in d
-            assert "Options" in d
             ret.append(
                 QemuDrive(
                     id=d["Id"],
-                    size=int(d["Size"]),
-                    directory=Path(d["Directory"]) if d["Directory"] else None,
-                    options=d["Options"],
+                    size=d["Size"] if isinstance(d["Size"], int) else parse_bytes(d["Size"]),
+                    directory=Path(d["Directory"]) if d.get("Directory") else None,
+                    options=d.get("Options"),
+                    file_id=d.get("FileId", d["Id"]),
                 )
             )
+
         return ret
 
     def generic_version_transformer(

diff --git a/mkosi/qemu.py b/mkosi/qemu.py
index 13b725d4b682d568b2d96460fd15256e964ae220..85c4294853db2edca9c5389b638aca3daf563bcc 100644 (file)
--- a/mkosi/qemu.py
+++ b/mkosi/qemu.py
@@ -46,7 +46,7 @@ from mkosi.sandbox import Mount
 from mkosi.tree import copy_tree, rmtree
 from mkosi.types import PathString
 from mkosi.user import INVOKING_USER, become_root, become_root_cmd
-from mkosi.util import StrEnum, flock, flock_or_die, try_or
+from mkosi.util import StrEnum, flock, flock_or_die, groupby, try_or
 from mkosi.versioncomp import GenericVersion
 
 QEMU_KVM_DEVICE_VERSION = GenericVersion("9.0")
@@ -1123,14 +1123,15 @@ def run_qemu(args: Args, config: Config) -> None:
                 f"type=11,value=io.systemd.boot.kernel-cmdline-extra={' '.join(kcl).replace(',', ',,')}",
             ]
 
-        for drive in config.qemu_drives:
-            file = stack.enter_context(finalize_drive(drive))
+        for _, drives in groupby(config.qemu_drives, key=lambda d: d.file_id):
+            file = stack.enter_context(finalize_drive(drives[0]))
 
-            arg = f"if=none,id={drive.id},file={file},format=raw"
-            if drive.options:
-                arg += f",{drive.options}"
+            for drive in drives:
+                arg = f"if=none,id={drive.id},file={file},format=raw,file.locking=off"
+                if drive.options:
+                    arg += f",{drive.options}"
 
-            cmdline += ["-drive", arg]
+                cmdline += ["-drive", arg]
 
         cmdline += config.qemu_args
         cmdline += args.cmdline

diff --git a/mkosi/resources/mkosi.md b/mkosi/resources/mkosi.md
index 965bd6044257584cdbf3b7f1eee0c8ef20a4156b..aa56c198ec68a2f12cf1f19d0fe1ce938b509510 100644 (file)
--- a/mkosi/resources/mkosi.md
+++ b/mkosi/resources/mkosi.md
@@ -1477,15 +1477,18 @@ boolean argument: either `1`, `yes`, or `true` to enable, or `0`, `no`,
 `QemuDrives=`, `--qemu-drive=`
 
 : Add a qemu drive. Takes a colon-delimited string of format
-  `<id>:<size>[:<directory>[:<options>]]`. `id` specifies the qemu id we
-  assign to the drive. This can be used as the `drive=` property in
-  various qemu devices. `size` specifies the size of the drive. This
-  takes a size in bytes. Additionally, the suffixes `K`, `M` and `G` can
-  be used to specify a size in kilobytes, megabytes and gigabytes
-  respectively. `directory` optionally specifies the directory in which
-  to create the file backing the drive. `options` optionally specifies
-  extra comma-delimited properties which are passed verbatim to qemu's
-  `-drive` option.
+  `<id>:<size>[:<directory>[:<options>[:<file-id>]]]`. `id` specifies
+  the qemu ID assigned to the drive. This can be used as the `drive=`
+  property in various qemu devices. `size` specifies the size of the
+  drive. This takes a size in bytes. Additionally, the suffixes `K`, `M`
+  and `G` can be used to specify a size in kilobytes, megabytes and
+  gigabytes respectively. `directory` optionally specifies the directory
+  in which to create the file backing the drive. `options` optionally
+  specifies extra comma-delimited properties which are passed verbatim
+  to qemu's `-drive` option. `file-id` specifies the ID of the file
+  backing the drive. Drives with the same file ID will share the
+  backing file. The directory and size of the file will be determined
+  from the first drive with a given file ID.
 
 : Example usage:
 

diff --git a/mkosi/util.py b/mkosi/util.py
index 6bd3ac3efaae117dd81e3dca63f968a2bba9f1c6..34c2c434bb305d2aae1b15bc555f0492e546110f 100644 (file)
--- a/mkosi/util.py
+++ b/mkosi/util.py
@@ -17,7 +17,7 @@ import re
 import resource
 import stat
 import tempfile
-from collections.abc import Iterable, Iterator, Mapping, Sequence
+from collections.abc import Hashable, Iterable, Iterator, Mapping, Sequence
 from pathlib import Path
 from types import ModuleType
 from typing import Any, Callable, Optional, TypeVar, no_type_check
@@ -27,6 +27,7 @@ from mkosi.types import PathString
 
 T = TypeVar("T")
 V = TypeVar("V")
+S = TypeVar("S", bound=Hashable)
 
 
 def dictify(f: Callable[..., Iterator[tuple[T, V]]]) -> Callable[..., dict[T, V]]:
@@ -319,3 +320,17 @@ def try_or(fn: Callable[..., T], exception: type[Exception], default: T) -> T:
         return fn()
     except exception:
         return default
+
+
+def groupby(seq: Sequence[T], key: Callable[[T], S]) -> list[tuple[S, list[T]]]:
+    grouped: dict[S, list[T]] = {}
+
+    for i in seq:
+        k = key(i)
+
+        if k not in grouped:
+            grouped[k] = []
+
+        grouped[k].append(i)
+
+    return [(key, group) for key, group in grouped.items()]

diff --git a/tests/test_json.py b/tests/test_json.py
index 3008bc7715919f6575ff14c5e74dffa17a1bde96..88ce42b332b75c4166bbe06c80f3c1e842fb1fdc 100644 (file)
--- a/tests/test_json.py
+++ b/tests/test_json.py
@@ -232,12 +232,14 @@ def test_config() -> None:
             "QemuDrives": [
                 {
                     "Directory": "/foo/bar",
+                    "FileId": "red",
                     "Id": "abc",
                     "Options": "abc,qed",
                     "Size": 200
                 },
                 {
                     "Directory": null,
+                    "FileId": "wcd",
                     "Id": "abc",
                     "Options": "",
                     "Size": 200
@@ -437,7 +439,10 @@ def test_config() -> None:
         proxy_url="https://my/proxy",
         qemu_args=[],
         qemu_cdrom=False,
-        qemu_drives=[QemuDrive("abc", 200, Path("/foo/bar"), "abc,qed"), QemuDrive("abc", 200, None, "")],
+        qemu_drives=[
+            QemuDrive("abc", 200, Path("/foo/bar"), "abc,qed", "red"),
+            QemuDrive("abc", 200, None, "", "wcd"),
+        ],
         qemu_firmware=QemuFirmware.linux,
         qemu_firmware_variables=Path("/foo/bar"),
         qemu_gui=True,