[PATCH 03/13] 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>
---
 block.c                   | 4 +++-
 block/qcow2.c             | 1 +
 include/block/block.h     | 1 +
 include/block/block_int.h | 1 +
 qemu-img-cmds.hx          | 4 ++--
 qemu-img.c                | 8 +++++++-
 qemu-img.texi             | 6 +++++-
 7 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/block.c b/block.c
index ecd09dbbfd..cb9d5f1965 100644
--- a/block.c
+++ b/block.c
@@ -6164,6 +6164,7 @@ 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) {
@@ -6175,7 +6176,8 @@ 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);
 }
 
 /* This function will be called by the bdrv_recurse_is_first_non_filter method
diff --git a/block/qcow2.c b/block/qcow2.c
index cef9d72b3a..6bcf4a5fc4 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -5150,6 +5150,7 @@ 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/include/block/block.h b/include/block/block.h
index e9dcfef7fa..d0cd1b2da0 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -399,6 +399,7 @@ 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);
 
 /* external snapshots */
diff --git a/include/block/block_int.h b/include/block/block_int.h
index dd033d0b37..810a9ecb86 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -427,6 +427,7 @@ 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 1c93e6d185..323ea10ad0 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -14,9 +14,9 @@ STEXI
 ETEXI
 
 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")
 STEXI
-@item amend [--object @var{objectdef}] [--image-opts] [-p] [-q] [-f @var{fmt}] [-t @var{cache}] -o @var{options} @var{filename}
+@item amend [--object @var{objectdef}] [--image-opts] [-p] [-q] [-f @var{fmt}] [-t @var{cache}] [--force] -o @var{options} @var{filename}
 ETEXI
 
 DEF("bench", img_bench,
diff --git a/qemu-img.c b/qemu-img.c
index 6233b8ca56..a79f3904db 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -70,6 +70,7 @@ enum {
     OPTION_PREALLOCATION = 265,
     OPTION_SHRINK = 266,
     OPTION_SALVAGE = 267,
+    OPTION_FORCE = 268,
 };
 
 typedef enum OutputFormat {
@@ -3900,6 +3901,7 @@ 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 (;;) {
@@ -3907,6 +3909,7 @@ 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",
@@ -3962,6 +3965,9 @@ static int img_amend(int argc, char **argv)
         case OPTION_IMAGE_OPTS:
             image_opts = true;
             break;
+        case OPTION_FORCE:
+            force = true;
+            break;
         }
     }
 
@@ -4039,7 +4045,7 @@ 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);
diff --git a/qemu-img.texi b/qemu-img.texi
index b5156d6316..b6ed4357e8 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -201,11 +201,15 @@ Command description:
 
 @table @option
 
-@item amend [--object @var{objectdef}] [--image-opts] [-p] [-q] [-f @var{fmt}] [-t @var{cache}] -o @var{options} @var{filename}
+@item amend [--object @var{objectdef}] [--image-opts] [-p] [-q] [-f @var{fmt}] [-t @var{cache}] [--force] -o @var{options} @var{filename}
 
 Amends the image format specific @var{options} for the image file
 @var{filename}. Not all file formats support this operation.
 
+--force allows some unsafe operations. Currently for -f luks,
+it allows to erase last encryption key, and to overwrite an active
+encryption key.
+
 @item bench [-c @var{count}] [-d @var{depth}] [-f @var{fmt}] [--flush-interval=@var{flush_interval}] [-n] [--no-drain] [-o @var{offset}] [--pattern=@var{pattern}] [-q] [-s @var{buffer_size}] [-S @var{step_size}] [-t @var{cache}] [-w] [-U] @var{filename}
 
 Run a simple sequential I/O benchmark on the specified image. If @code{-w} is
-- 
2.17.2