Re: [libvirt] [RFC PATCH 1/2] qemu: caps: Add capability for dynamic 'auto-read-only' support for files

Initial implementation of 'auto-read-only' didn't reopen the backing files when needed. For '-blockdev' to work we need to be able to tel

qemu to open a file read-only and change it during blockjobs as we label backing chains with a sVirt label which does not allow writing. The dynamic auto-read-only supports this as it reopens files when writing is demanded. Add a capability to detect that the posix file based backends support the dynamic part. Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; Reviewed-by: Jiri Denemark <jdenemar(a)redhat.com&gt; --- src/qemu/qemu_capabilities.c | 2 ++ src/qemu/qemu_capabilities.h | 1 + tests/qemucapabilitiesdata/caps_4.1.0.x86_64.xml | 1 + 3 files changed, 4 insertions(+) diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index c9677315ab..83b1a12d14 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -537,6 +537,7 @@ VIR_ENUM_IMPL(virQEMUCaps, /* 335 */ "bochs-display", "migration-file-drop-cache", + "blockdev-file-dynamic-auto-read-only",

); @@ -1281,6 +1282,7 @@ static struct virQEMUCapsStringFlags virQEMUCapsQMPSchemaQueries[] = { { "query-display-options/ret-type/+egl-headless/rendernode", QEMU_CAPS_EGL_HEADLESS_RENDERNODE }, { "nbd-server-add/arg-type/bitmap", QEMU_CAPS_NBD_BITMAP }, { "blockdev-add/arg-type/+file/drop-cache", QEMU_CAPS_MIGRATION_FILE_DROP_CACHE }, + { "blockdev-add/arg-type/+file/$dynamic-auto-read-only", QEMU_CAPS_BLOCK_FILE_AUTO_READONLY_DYNAMIC }, }; typedef struct _virQEMUCapsObjectTypeProps virQEMUCapsObjectTypeProps; diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h index 68ef6c49b4..2fe0e26ced 100644 --- a/src/qemu/qemu_capabilities.h +++ b/src/qemu/qemu_capabilities.h @@ -518,6 +518,7 @@ typedef enum { /* virQEMUCapsFlags grouping marker for syntax-check */ /* 335 */ QEMU_CAPS_DEVICE_BOCHS_DISPLAY, /* -device bochs-display */ QEMU_CAPS_MIGRATION_FILE_DROP_CACHE, /* migration with disk cache on is safe for type='file' disks */ + QEMU_CAPS_BLOCK_FILE_AUTO_READONLY_DYNAMIC, /* the auto-read-only property of block backends for files is dynamic */

QEMU_CAPS_LAST /* this must always be the last item */ } virQEMUCapsFlags;