[PATCH v5 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>
---
 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 cf5c19b1db..de2e41b361 100644
--- a/block.c
+++ b/block.c
@@ -6377,6 +6377,7 @@ 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) {
@@ -6388,7 +6389,8 @@ 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 ad934109a8..06c0e77cfe 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -5219,6 +5219,7 @@ 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 0080f83a76..fc2dca6649 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -249,11 +249,14 @@ 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 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 8b62429aa4..0ca53b5598 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -392,6 +392,7 @@ 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 92335f33c7..98671ecdf6 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -432,6 +432,7 @@ 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 c9c54de1df..9920f1f9d4 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 qemu-img.texi.
 
 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 6a4327aaba..ef422d5471 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -71,6 +71,7 @@ enum {
     OPTION_SHRINK = 266,
     OPTION_SALVAGE = 267,
     OPTION_TARGET_IS_ZERO = 268,
+    OPTION_FORCE = 269,
 };
 
 typedef enum OutputFormat {
@@ -3958,6 +3959,7 @@ 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 (;;) {
@@ -3965,6 +3967,7 @@ 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",
@@ -4012,6 +4015,9 @@ static int img_amend(int argc, char **argv)
         case OPTION_IMAGE_OPTS:
             image_opts = true;
             break;
+        case OPTION_FORCE:
+            force = true;
+            break;
         }
     }
 
@@ -4089,7 +4095,7 @@ 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);
-- 
2.17.2