[PATCH v8 03/14] block/amend: add 'force' option

[Maxim Levitsky <mlevitsk@redhat.com>]

'force' option will be used for some unsafe amend operations.

This includes things like erasing last keyslot in luks based formats
(which destroys the data, unless the master key is backed up
by external means), but that _might_ be desired result.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 block.c                   | 4 +++-
 block/qcow2.c             | 1 +
 docs/tools/qemu-img.rst   | 5 ++++-
 include/block/block.h     | 1 +
 include/block/block_int.h | 1 +
 qemu-img-cmds.hx          | 4 ++--
 qemu-img.c                | 8 +++++++-
 7 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/block.c b/block.c
index 8416376c9b..10a1e87d1e 100644
--- a/block.c
+++ b/block.c
@@ -6482,6 +6482,7 @@ void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
 
 int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
                        BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
+                       bool force,
                        Error **errp)
 {
     if (!bs->drv) {
@@ -6493,7 +6494,8 @@ int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
                    bs->drv->format_name);
         return -ENOTSUP;
     }
-    return bs->drv->bdrv_amend_options(bs, opts, status_cb, cb_opaque, errp);
+    return bs->drv->bdrv_amend_options(bs, opts, status_cb,
+                                       cb_opaque, force, errp);
 }
 
 /*
diff --git a/block/qcow2.c b/block/qcow2.c
index 0cd2e6757e..2ab0c382f7 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -5340,6 +5340,7 @@ static void qcow2_amend_helper_cb(BlockDriverState *bs,
 static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
                                BlockDriverAmendStatusCB *status_cb,
                                void *cb_opaque,
+                               bool force,
                                Error **errp)
 {
     BDRVQcow2State *s = bs->opaque;
diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index 69cd9a3037..f14332ea50 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -253,11 +253,14 @@ Command description:
 
 .. program:: qemu-img-commands
 
-.. option:: amend [--object OBJECTDEF] [--image-opts] [-p] [-q] [-f FMT] [-t CACHE] -o OPTIONS FILENAME
+.. option:: amend [--object OBJECTDEF] [--image-opts] [-p] [-q] [-f FMT] [-t CACHE] [--force] -o OPTIONS FILENAME
 
   Amends the image format specific *OPTIONS* for the image file
   *FILENAME*. Not all file formats support this operation.
 
+  --force allows some unsafe operations. Currently for -f luks, it allows to
+  erase the last encryption key, and to overwrite an active encryption key.
+
 .. option:: bench [-c COUNT] [-d DEPTH] [-f FMT] [--flush-interval=FLUSH_INTERVAL] [-i AIO] [-n] [--no-drain] [-o OFFSET] [--pattern=PATTERN] [-q] [-s BUFFER_SIZE] [-S STEP_SIZE] [-t CACHE] [-w] [-U] FILENAME
 
   Run a simple sequential I/O benchmark on the specified image. If ``-w`` is
diff --git a/include/block/block.h b/include/block/block.h
index 25e299605e..86f9728f00 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -450,6 +450,7 @@ typedef void BlockDriverAmendStatusCB(BlockDriverState *bs, int64_t offset,
                                       int64_t total_work_size, void *opaque);
 int bdrv_amend_options(BlockDriverState *bs_new, QemuOpts *opts,
                        BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
+                       bool force,
                        Error **errp);
 
 /* check if a named node can be replaced when doing drive-mirror */
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 791de6a59c..066b9eaa40 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -440,6 +440,7 @@ struct BlockDriver {
     int (*bdrv_amend_options)(BlockDriverState *bs, QemuOpts *opts,
                               BlockDriverAmendStatusCB *status_cb,
                               void *cb_opaque,
+                              bool force,
                               Error **errp);
 
     void (*bdrv_debug_event)(BlockDriverState *bs, BlkdebugEvent event);
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index 10b910b67c..b89c019b76 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -10,9 +10,9 @@ HXCOMM When amending the rST sections, please remember to copy the usage
 HXCOMM over to the per-command sections in docs/tools/qemu-img.rst.
 
 DEF("amend", img_amend,
-    "amend [--object objectdef] [--image-opts] [-p] [-q] [-f fmt] [-t cache] -o options filename")
+    "amend [--object objectdef] [--image-opts] [-p] [-q] [-f fmt] [-t cache] [--force] -o options filename")
 SRST
-.. option:: amend [--object OBJECTDEF] [--image-opts] [-p] [-q] [-f FMT] [-t CACHE] -o OPTIONS FILENAME
+.. option:: amend [--object OBJECTDEF] [--image-opts] [-p] [-q] [-f FMT] [-t CACHE] [--force] -o OPTIONS FILENAME
 ERST
 
 DEF("bench", img_bench,
diff --git a/qemu-img.c b/qemu-img.c
index d7e846e607..10d81f09db 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -79,6 +79,7 @@ enum {
     OPTION_DISABLE = 273,
     OPTION_MERGE = 274,
     OPTION_BITMAPS = 275,
+    OPTION_FORCE = 276,
 };
 
 typedef enum OutputFormat {
@@ -4099,6 +4100,7 @@ static int img_amend(int argc, char **argv)
     BlockBackend *blk = NULL;
     BlockDriverState *bs = NULL;
     bool image_opts = false;
+    bool force = false;
 
     cache = BDRV_DEFAULT_CACHE;
     for (;;) {
@@ -4106,6 +4108,7 @@ static int img_amend(int argc, char **argv)
             {"help", no_argument, 0, 'h'},
             {"object", required_argument, 0, OPTION_OBJECT},
             {"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
+            {"force", no_argument, 0, OPTION_FORCE},
             {0, 0, 0, 0}
         };
         c = getopt_long(argc, argv, ":ho:f:t:pq",
@@ -4153,6 +4156,9 @@ static int img_amend(int argc, char **argv)
         case OPTION_IMAGE_OPTS:
             image_opts = true;
             break;
+        case OPTION_FORCE:
+            force = true;
+            break;
         }
     }
 
@@ -4230,7 +4236,7 @@ static int img_amend(int argc, char **argv)
 
     /* In case the driver does not call amend_status_cb() */
     qemu_progress_print(0.f, 0);
-    ret = bdrv_amend_options(bs, opts, &amend_status_cb, NULL, &err);
+    ret = bdrv_amend_options(bs, opts, &amend_status_cb, NULL, force, &err);
     qemu_progress_print(100.f, 0);
     if (ret < 0) {
         error_report_err(err);
-- 
2.25.4