[PATCH 0/2] Let 'qemu-img convert --bitmaps' skip inconsistent bitmaps

[PATCH 0/2] Let 'qemu-img convert --bitmaps' skip inconsistent bitmaps

[Eric Blake]

This is mostly a convenience factor as one could already use 'qemu-img
info' to learn which bitmaps are broken and then 'qemu-img bitmap
--remove' to nuke them before calling 'qemu-img convert --bitmaps',
but it does have the advantage that the copied file is usable without
extra efforts and the broken bitmap is not deleted from the source
file.

Eric Blake (2):
  iotests: Improve and rename test 291 to qemu-img-bitmap
  qemu-img: Add --skip-broken for 'convert --bitmaps'

 docs/tools/qemu-img.rst                       |  8 +++-
 block/dirty-bitmap.c                          |  2 +-
 qemu-img.c                                    | 20 +++++++-
 .../{291 => tests/qemu-img-bitmaps}           | 17 ++++++-
 .../{291.out => tests/qemu-img-bitmaps.out}   | 46 ++++++++++++++++++-
 5 files changed, 87 insertions(+), 6 deletions(-)
 rename tests/qemu-iotests/{291 => tests/qemu-img-bitmaps} (88%)
 rename tests/qemu-iotests/{291.out => tests/qemu-img-bitmaps.out} (76%)

-- 
2.31.1

[PATCH 1/2] iotests: Improve and rename test 291 to qemu-img-bitmap

[Eric Blake]

Enhance the test to demonstrate behavior of qemu-img with a qcow2
image containing an inconsistent bitmap, and rename it now that we
support useful iotest names.

While at it, fix a missing newline in the error message thus exposed.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 block/dirty-bitmap.c                          |  2 +-
 .../{291 => tests/qemu-img-bitmaps}           | 13 +++++++-
 .../{291.out => tests/qemu-img-bitmaps.out}   | 32 ++++++++++++++++++-
 3 files changed, 44 insertions(+), 3 deletions(-)
 rename tests/qemu-iotests/{291 => tests/qemu-img-bitmaps} (92%)
 rename tests/qemu-iotests/{291.out => tests/qemu-img-bitmaps.out} (82%)

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index 68d295d6e3ed..0ef46163e3ea 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -193,7 +193,7 @@ int bdrv_dirty_bitmap_check(const BdrvDirtyBitmap *bitmap, uint32_t flags,
         error_setg(errp, "Bitmap '%s' is inconsistent and cannot be used",
                    bitmap->name);
         error_append_hint(errp, "Try block-dirty-bitmap-remove to delete"
-                          " this bitmap from disk");
+                          " this bitmap from disk\n");
         return -1;
     }

diff --git a/tests/qemu-iotests/291 b/tests/qemu-iotests/tests/qemu-img-bitmaps
similarity index 92%
rename from tests/qemu-iotests/291
rename to tests/qemu-iotests/tests/qemu-img-bitmaps
index 20efb080a6c0..76cd9e31e850 100755
--- a/tests/qemu-iotests/291
+++ b/tests/qemu-iotests/tests/qemu-img-bitmaps
@@ -3,7 +3,7 @@
 #
 # Test qemu-img bitmap handling
 #
-# Copyright (C) 2018-2020 Red Hat, Inc.
+# Copyright (C) 2018-2021 Red Hat, Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -32,6 +32,7 @@ _cleanup()
 trap "_cleanup; exit \$status" 0 1 2 3 15

 # get standard environment, filters and checks
+cd ..
 . ./common.rc
 . ./common.filter
 . ./common.nbd
@@ -129,6 +130,16 @@ $QEMU_IMG map --output=json --image-opts \

 nbd_server_stop

+echo
+echo "=== Check handling of inconsistent bitmap ==="
+echo
+
+$QEMU_IO -c abort "$TEST_IMG" 2>/dev/null
+$QEMU_IMG bitmap --add "$TEST_IMG" b4
+$QEMU_IMG bitmap --remove "$TEST_IMG" b1
+_img_info --format-specific | _filter_irrelevant_img_info
+$QEMU_IMG convert --bitmaps -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
+
 # success, all done
 echo '*** done'
 rm -f $seq.full
diff --git a/tests/qemu-iotests/291.out b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
similarity index 82%
rename from tests/qemu-iotests/291.out
rename to tests/qemu-iotests/tests/qemu-img-bitmaps.out
index 018d6b103f87..17b34eaed30f 100644
--- a/tests/qemu-iotests/291.out
+++ b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
@@ -1,4 +1,4 @@
-QA output created by 291
+QA output created by qemu-img-bitmaps

 === Initial image setup ===

@@ -115,4 +115,34 @@ Format specific information:
 [{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
 { "start": 2097152, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false},
 { "start": 3145728, "length": 7340032, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
+
+=== Check handling of inconsistent bitmap ===
+
+image: TEST_DIR/t.IMGFMT
+file format: IMGFMT
+virtual size: 10 MiB (10485760 bytes)
+cluster_size: 65536
+backing file: TEST_DIR/t.IMGFMT.base
+backing file format: IMGFMT
+Format specific information:
+    bitmaps:
+        [0]:
+            flags:
+                [0]: in-use
+                [1]: auto
+            name: b2
+            granularity: 65536
+        [1]:
+            flags:
+                [0]: in-use
+            name: b0
+            granularity: 65536
+        [2]:
+            flags:
+                [0]: auto
+            name: b4
+            granularity: 65536
+    corrupt: false
+qemu-img: Failed to populate bitmap b0: Bitmap 'b0' is inconsistent and cannot be used
+Try block-dirty-bitmap-remove to delete this bitmap from disk
 *** done
-- 
2.31.1

[PATCH 2/2] qemu-img: Add --skip-broken for 'convert --bitmaps'

[Eric Blake]

The point of 'qemu-img convert --bitmaps' is to be a convenience for
actions that are already possible through a string of smaller
'qemu-img bitmap' sub-commands.  One situation not accounted for
already is that if a source image contains an inconsistent bitmap (for
example, because a qemu process died abruptly before flushing bitmap
state), the user MUST delete those inconsistent bitmaps before
anything else useful can be done with the image.

We don't want to delete inconsistent bitmaps by default: although a
corrupt bitmap is only a loss of optimization rather than a corruption
of user-visible data, it is still nice to require the user to opt in
to the fact that they are aware of the loss of the bitmap.  Still,
requiring the user to check 'qemu-img info' to see whether bitmaps are
consistent, then use 'qemu-img bitmap --remove' to remove offenders,
all before using 'qemu-img convert', is a lot more work than just
adding a knob 'qemu-img convert --bitmaps --skip-broken' which opts in
to skipping the broken bitmaps.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1946084
Signed-off-by: Eric Blake <eblake@redhat.com>
---
 docs/tools/qemu-img.rst                       |  8 +++++++-
 qemu-img.c                                    | 20 +++++++++++++++++--
 tests/qemu-iotests/tests/qemu-img-bitmaps     |  4 ++++
 tests/qemu-iotests/tests/qemu-img-bitmaps.out | 14 +++++++++++++
 4 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index 1d8470eada0e..5cf1c764597b 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -414,7 +414,7 @@ Command description:
   4
     Error on reading data

-.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] [--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-r RATE_LIMIT] [-m NUM_COROUTINES] [-W] FILENAME [FILENAME2 [...]] OUTPUT_FILENAME
+.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] [--target-is-zero] [--bitmaps [--skip-broken]] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-r RATE_LIMIT] [-m NUM_COROUTINES] [-W] FILENAME [FILENAME2 [...]] OUTPUT_FILENAME

   Convert the disk image *FILENAME* or a snapshot *SNAPSHOT_PARAM*
   to disk image *OUTPUT_FILENAME* using format *OUTPUT_FMT*. It can
@@ -456,6 +456,12 @@ Command description:
   *NUM_COROUTINES* specifies how many coroutines work in parallel during
   the convert process (defaults to 8).

+  Use of ``--bitmaps`` requests that any persistent bitmaps present in
+  the original are also copied to the destination.  If any bitmap is
+  inconsistent in the source, the conversion will fail unless
+  ``--skip-broken`` is also specified to copy only the consistent
+  bitmaps.
+
 .. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE] [-F BACKING_FMT] [-u] [-o OPTIONS] FILENAME [SIZE]

   Create the new disk image *FILENAME* of size *SIZE* and format
diff --git a/qemu-img.c b/qemu-img.c
index 68a4d298098f..e8b012f39c0c 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -82,6 +82,7 @@ enum {
     OPTION_MERGE = 274,
     OPTION_BITMAPS = 275,
     OPTION_FORCE = 276,
+    OPTION_SKIP_BROKEN = 277,
 };

 typedef enum OutputFormat {
@@ -2101,7 +2102,8 @@ static int convert_do_copy(ImgConvertState *s)
     return s->ret;
 }

-static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst)
+static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst,
+                                bool skip_broken)
 {
     BdrvDirtyBitmap *bm;
     Error *err = NULL;
@@ -2113,6 +2115,10 @@ static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst)
             continue;
         }
         name = bdrv_dirty_bitmap_name(bm);
+        if (skip_broken && bdrv_dirty_bitmap_inconsistent(bm)) {
+            warn_report("Skipping inconsistent bitmap %s", name);
+            continue;
+        }
         qmp_block_dirty_bitmap_add(dst->node_name, name,
                                    true, bdrv_dirty_bitmap_granularity(bm),
                                    true, true,
@@ -2167,6 +2173,7 @@ static int img_convert(int argc, char **argv)
     bool force_share = false;
     bool explict_min_sparse = false;
     bool bitmaps = false;
+    bool skip_broken = false;
     int64_t rate_limit = 0;

     ImgConvertState s = (ImgConvertState) {
@@ -2188,6 +2195,7 @@ static int img_convert(int argc, char **argv)
             {"salvage", no_argument, 0, OPTION_SALVAGE},
             {"target-is-zero", no_argument, 0, OPTION_TARGET_IS_ZERO},
             {"bitmaps", no_argument, 0, OPTION_BITMAPS},
+            {"skip-broken", no_argument, 0, OPTION_SKIP_BROKEN},
             {0, 0, 0, 0}
         };
         c = getopt_long(argc, argv, ":hf:O:B:Cco:l:S:pt:T:qnm:WUr:",
@@ -2316,6 +2324,9 @@ static int img_convert(int argc, char **argv)
         case OPTION_BITMAPS:
             bitmaps = true;
             break;
+        case OPTION_SKIP_BROKEN:
+            skip_broken = true;
+            break;
         }
     }

@@ -2323,6 +2334,11 @@ static int img_convert(int argc, char **argv)
         out_fmt = "raw";
     }

+    if (skip_broken && !bitmaps) {
+        error_report("Use of --skip-broken requires --bitmaps");
+        goto fail_getopt;
+    }
+
     if (s.compressed && s.copy_range) {
         error_report("Cannot enable copy offloading when -c is used");
         goto fail_getopt;
@@ -2678,7 +2694,7 @@ static int img_convert(int argc, char **argv)

     /* Now copy the bitmaps */
     if (bitmaps && ret == 0) {
-        ret = convert_copy_bitmaps(blk_bs(s.src[0]), out_bs);
+        ret = convert_copy_bitmaps(blk_bs(s.src[0]), out_bs, skip_broken);
     }

 out:
diff --git a/tests/qemu-iotests/tests/qemu-img-bitmaps b/tests/qemu-iotests/tests/qemu-img-bitmaps
index 76cd9e31e850..3e1a39bc81e4 100755
--- a/tests/qemu-iotests/tests/qemu-img-bitmaps
+++ b/tests/qemu-iotests/tests/qemu-img-bitmaps
@@ -28,6 +28,7 @@ _cleanup()
 {
     _cleanup_test_img
     nbd_server_stop
+    _rm_test_img "$TEST_DIR/t.$IMGFMT.copy"
 }
 trap "_cleanup; exit \$status" 0 1 2 3 15

@@ -139,6 +140,9 @@ $QEMU_IMG bitmap --add "$TEST_IMG" b4
 $QEMU_IMG bitmap --remove "$TEST_IMG" b1
 _img_info --format-specific | _filter_irrelevant_img_info
 $QEMU_IMG convert --bitmaps -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
+$QEMU_IMG convert --bitmaps --skip-broken -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
+TEST_IMG="$TEST_IMG.copy" _img_info --format-specific \
+    | _filter_irrelevant_img_info

 # success, all done
 echo '*** done'
diff --git a/tests/qemu-iotests/tests/qemu-img-bitmaps.out b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
index 17b34eaed30f..685bde6d1d63 100644
--- a/tests/qemu-iotests/tests/qemu-img-bitmaps.out
+++ b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
@@ -145,4 +145,18 @@ Format specific information:
     corrupt: false
 qemu-img: Failed to populate bitmap b0: Bitmap 'b0' is inconsistent and cannot be used
 Try block-dirty-bitmap-remove to delete this bitmap from disk
+qemu-img: warning: Skipping inconsistent bitmap b0
+qemu-img: warning: Skipping inconsistent bitmap b2
+image: TEST_DIR/t.IMGFMT.copy
+file format: IMGFMT
+virtual size: 10 MiB (10485760 bytes)
+cluster_size: 65536
+Format specific information:
+    bitmaps:
+        [0]:
+            flags:
+                [0]: auto
+            name: b4
+            granularity: 65536
+    corrupt: false
 *** done
-- 
2.31.1

Re: [PATCH 1/2] iotests: Improve and rename test 291 to qemu-img-bitmap

[Vladimir Sementsov-Ogievskiy]

08.07.2021 04:30, Eric Blake wrote:
> Enhance the test to demonstrate behavior of qemu-img with a qcow2
> image containing an inconsistent bitmap, and rename it now that we
> support useful iotest names.
> 
> While at it, fix a missing newline in the error message thus exposed.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>   block/dirty-bitmap.c                          |  2 +-
>   .../{291 => tests/qemu-img-bitmaps}           | 13 +++++++-
>   .../{291.out => tests/qemu-img-bitmaps.out}   | 32 ++++++++++++++++++-
>   3 files changed, 44 insertions(+), 3 deletions(-)
>   rename tests/qemu-iotests/{291 => tests/qemu-img-bitmaps} (92%)
>   rename tests/qemu-iotests/{291.out => tests/qemu-img-bitmaps.out} (82%)
> 
> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
> index 68d295d6e3ed..0ef46163e3ea 100644
> --- a/block/dirty-bitmap.c
> +++ b/block/dirty-bitmap.c
> @@ -193,7 +193,7 @@ int bdrv_dirty_bitmap_check(const BdrvDirtyBitmap *bitmap, uint32_t flags,
>           error_setg(errp, "Bitmap '%s' is inconsistent and cannot be used",
>                      bitmap->name);
>           error_append_hint(errp, "Try block-dirty-bitmap-remove to delete"
> -                          " this bitmap from disk");
> +                          " this bitmap from disk\n");
>           return -1;
>       }
> 
> diff --git a/tests/qemu-iotests/291 b/tests/qemu-iotests/tests/qemu-img-bitmaps
> similarity index 92%
> rename from tests/qemu-iotests/291
> rename to tests/qemu-iotests/tests/qemu-img-bitmaps
> index 20efb080a6c0..76cd9e31e850 100755
> --- a/tests/qemu-iotests/291
> +++ b/tests/qemu-iotests/tests/qemu-img-bitmaps
> @@ -3,7 +3,7 @@
>   #
>   # Test qemu-img bitmap handling
>   #
> -# Copyright (C) 2018-2020 Red Hat, Inc.
> +# Copyright (C) 2018-2021 Red Hat, Inc.
>   #
>   # This program is free software; you can redistribute it and/or modify
>   # it under the terms of the GNU General Public License as published by
> @@ -32,6 +32,7 @@ _cleanup()
>   trap "_cleanup; exit \$status" 0 1 2 3 15
> 
>   # get standard environment, filters and checks
> +cd ..
>   . ./common.rc
>   . ./common.filter
>   . ./common.nbd
> @@ -129,6 +130,16 @@ $QEMU_IMG map --output=json --image-opts \
> 
>   nbd_server_stop
> 
> +echo
> +echo "=== Check handling of inconsistent bitmap ==="
> +echo
> +
> +$QEMU_IO -c abort "$TEST_IMG" 2>/dev/null
> +$QEMU_IMG bitmap --add "$TEST_IMG" b4
> +$QEMU_IMG bitmap --remove "$TEST_IMG" b1
> +_img_info --format-specific | _filter_irrelevant_img_info
> +$QEMU_IMG convert --bitmaps -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"

Worth then removing remaining inconsistent bitmaps and try again?

I think you should now remove $TEST_IMG.copy in _cleanup

with squashed in

--- a/tests/qemu-iotests/tests/qemu-img-bitmaps
+++ b/tests/qemu-iotests/tests/qemu-img-bitmaps
@@ -27,6 +27,7 @@ status=1 # failure is the default!
  _cleanup()
  {
      _cleanup_test_img
+    _rm_test_img "$TEST_IMG.copy"
      nbd_server_stop
  }
  trap "_cl

Tested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

> +
>   # success, all done
>   echo '*** done'
>   rm -f $seq.full
> diff --git a/tests/qemu-iotests/291.out b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
> similarity index 82%
> rename from tests/qemu-iotests/291.out
> rename to tests/qemu-iotests/tests/qemu-img-bitmaps.out
> index 018d6b103f87..17b34eaed30f 100644
> --- a/tests/qemu-iotests/291.out
> +++ b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
> @@ -1,4 +1,4 @@
> -QA output created by 291
> +QA output created by qemu-img-bitmaps
> 
>   === Initial image setup ===
> 
> @@ -115,4 +115,34 @@ Format specific information:
>   [{ "start": 0, "length": 2097152, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET},
>   { "start": 2097152, "length": 1048576, "depth": 0, "present": false, "zero": false, "data": false},
>   { "start": 3145728, "length": 7340032, "depth": 0, "present": true, "zero": false, "data": true, "offset": OFFSET}]
> +
> +=== Check handling of inconsistent bitmap ===
> +
> +image: TEST_DIR/t.IMGFMT
> +file format: IMGFMT
> +virtual size: 10 MiB (10485760 bytes)
> +cluster_size: 65536
> +backing file: TEST_DIR/t.IMGFMT.base
> +backing file format: IMGFMT
> +Format specific information:
> +    bitmaps:
> +        [0]:
> +            flags:
> +                [0]: in-use
> +                [1]: auto
> +            name: b2
> +            granularity: 65536
> +        [1]:
> +            flags:
> +                [0]: in-use
> +            name: b0
> +            granularity: 65536
> +        [2]:
> +            flags:
> +                [0]: auto
> +            name: b4
> +            granularity: 65536
> +    corrupt: false
> +qemu-img: Failed to populate bitmap b0: Bitmap 'b0' is inconsistent and cannot be used
> +Try block-dirty-bitmap-remove to delete this bitmap from disk
>   *** done
> 


-- 
Best regards,
Vladimir

Re: [PATCH 2/2] qemu-img: Add --skip-broken for 'convert --bitmaps'

[Vladimir Sementsov-Ogievskiy]

08.07.2021 04:30, Eric Blake wrote:
> The point of 'qemu-img convert --bitmaps' is to be a convenience for
> actions that are already possible through a string of smaller
> 'qemu-img bitmap' sub-commands.  One situation not accounted for
> already is that if a source image contains an inconsistent bitmap (for
> example, because a qemu process died abruptly before flushing bitmap
> state), the user MUST delete those inconsistent bitmaps before
> anything else useful can be done with the image.
> 
> We don't want to delete inconsistent bitmaps by default: although a
> corrupt bitmap is only a loss of optimization rather than a corruption
> of user-visible data, it is still nice to require the user to opt in
> to the fact that they are aware of the loss of the bitmap.  Still,
> requiring the user to check 'qemu-img info' to see whether bitmaps are
> consistent, then use 'qemu-img bitmap --remove' to remove offenders,
> all before using 'qemu-img convert', is a lot more work than just
> adding a knob 'qemu-img convert --bitmaps --skip-broken' which opts in
> to skipping the broken bitmaps.
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1946084
> Signed-off-by: Eric Blake <eblake@redhat.com>
> ---
>   docs/tools/qemu-img.rst                       |  8 +++++++-
>   qemu-img.c                                    | 20 +++++++++++++++++--
>   tests/qemu-iotests/tests/qemu-img-bitmaps     |  4 ++++
>   tests/qemu-iotests/tests/qemu-img-bitmaps.out | 14 +++++++++++++
>   4 files changed, 43 insertions(+), 3 deletions(-)
> 
> diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
> index 1d8470eada0e..5cf1c764597b 100644
> --- a/docs/tools/qemu-img.rst
> +++ b/docs/tools/qemu-img.rst
> @@ -414,7 +414,7 @@ Command description:
>     4
>       Error on reading data
> 
> -.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] [--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-r RATE_LIMIT] [-m NUM_COROUTINES] [-W] FILENAME [FILENAME2 [...]] OUTPUT_FILENAME
> +.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] [--target-is-zero] [--bitmaps [--skip-broken]] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-r RATE_LIMIT] [-m NUM_COROUTINES] [-W] FILENAME [FILENAME2 [...]] OUTPUT_FILENAME

Of course, [--bitmaps [--skip-broken]] looks like --skip-broken is a suboption.. But actually it's not so. So, shouldn't it be named more explicit, like --skip-broken-bitmaps ? To be sure that we will not interfere in future with some other broken things we want to skip? And to avoid strange but correct command lines like

qemu-img convert --skip-broken <someother options> --bitmaps <some other options> src dst


> 
>     Convert the disk image *FILENAME* or a snapshot *SNAPSHOT_PARAM*
>     to disk image *OUTPUT_FILENAME* using format *OUTPUT_FMT*. It can
> @@ -456,6 +456,12 @@ Command description:
>     *NUM_COROUTINES* specifies how many coroutines work in parallel during
>     the convert process (defaults to 8).
> 
> +  Use of ``--bitmaps`` requests that any persistent bitmaps present in
> +  the original are also copied to the destination.  If any bitmap is
> +  inconsistent in the source, the conversion will fail unless
> +  ``--skip-broken`` is also specified to copy only the consistent
> +  bitmaps.
> +
>   .. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE] [-F BACKING_FMT] [-u] [-o OPTIONS] FILENAME [SIZE]
> 
>     Create the new disk image *FILENAME* of size *SIZE* and format
> diff --git a/qemu-img.c b/qemu-img.c
> index 68a4d298098f..e8b012f39c0c 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -82,6 +82,7 @@ enum {
>       OPTION_MERGE = 274,
>       OPTION_BITMAPS = 275,
>       OPTION_FORCE = 276,
> +    OPTION_SKIP_BROKEN = 277,
>   };
> 
>   typedef enum OutputFormat {
> @@ -2101,7 +2102,8 @@ static int convert_do_copy(ImgConvertState *s)
>       return s->ret;
>   }
> 
> -static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst)
> +static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst,
> +                                bool skip_broken)
>   {
>       BdrvDirtyBitmap *bm;
>       Error *err = NULL;
> @@ -2113,6 +2115,10 @@ static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst)
>               continue;
>           }
>           name = bdrv_dirty_bitmap_name(bm);
> +        if (skip_broken && bdrv_dirty_bitmap_inconsistent(bm)) {
> +            warn_report("Skipping inconsistent bitmap %s", name);
> +            continue;
> +        }
>           qmp_block_dirty_bitmap_add(dst->node_name, name,
>                                      true, bdrv_dirty_bitmap_granularity(bm),
>                                      true, true,
> @@ -2167,6 +2173,7 @@ static int img_convert(int argc, char **argv)
>       bool force_share = false;
>       bool explict_min_sparse = false;
>       bool bitmaps = false;
> +    bool skip_broken = false;
>       int64_t rate_limit = 0;
> 
>       ImgConvertState s = (ImgConvertState) {
> @@ -2188,6 +2195,7 @@ static int img_convert(int argc, char **argv)
>               {"salvage", no_argument, 0, OPTION_SALVAGE},
>               {"target-is-zero", no_argument, 0, OPTION_TARGET_IS_ZERO},
>               {"bitmaps", no_argument, 0, OPTION_BITMAPS},
> +            {"skip-broken", no_argument, 0, OPTION_SKIP_BROKEN},
>               {0, 0, 0, 0}
>           };
>           c = getopt_long(argc, argv, ":hf:O:B:Cco:l:S:pt:T:qnm:WUr:",
> @@ -2316,6 +2324,9 @@ static int img_convert(int argc, char **argv)
>           case OPTION_BITMAPS:
>               bitmaps = true;
>               break;
> +        case OPTION_SKIP_BROKEN:
> +            skip_broken = true;
> +            break;
>           }
>       }
> 
> @@ -2323,6 +2334,11 @@ static int img_convert(int argc, char **argv)
>           out_fmt = "raw";
>       }
> 
> +    if (skip_broken && !bitmaps) {
> +        error_report("Use of --skip-broken requires --bitmaps");
> +        goto fail_getopt;
> +    }
> +
>       if (s.compressed && s.copy_range) {
>           error_report("Cannot enable copy offloading when -c is used");
>           goto fail_getopt;
> @@ -2678,7 +2694,7 @@ static int img_convert(int argc, char **argv)
> 
>       /* Now copy the bitmaps */
>       if (bitmaps && ret == 0) {
> -        ret = convert_copy_bitmaps(blk_bs(s.src[0]), out_bs);
> +        ret = convert_copy_bitmaps(blk_bs(s.src[0]), out_bs, skip_broken);
>       }
> 
>   out:
> diff --git a/tests/qemu-iotests/tests/qemu-img-bitmaps b/tests/qemu-iotests/tests/qemu-img-bitmaps
> index 76cd9e31e850..3e1a39bc81e4 100755
> --- a/tests/qemu-iotests/tests/qemu-img-bitmaps
> +++ b/tests/qemu-iotests/tests/qemu-img-bitmaps
> @@ -28,6 +28,7 @@ _cleanup()
>   {
>       _cleanup_test_img
>       nbd_server_stop
> +    _rm_test_img "$TEST_DIR/t.$IMGFMT.copy"

Aha here it is. It should appear in a previous patch..

Also, it may be simply

_rm_test_img "$TEST_IMG.copy"

, like in 110.

>   }
>   trap "_cleanup; exit \$status" 0 1 2 3 15
> 
> @@ -139,6 +140,9 @@ $QEMU_IMG bitmap --add "$TEST_IMG" b4
>   $QEMU_IMG bitmap --remove "$TEST_IMG" b1
>   _img_info --format-specific | _filter_irrelevant_img_info
>   $QEMU_IMG convert --bitmaps -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
> +$QEMU_IMG convert --bitmaps --skip-broken -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
> +TEST_IMG="$TEST_IMG.copy" _img_info --format-specific \
> +    | _filter_irrelevant_img_info


We still can now remove remaining inconsistent bitmaps and retry convert without --skip-broken, just to cover more nearby cases.

> 
>   # success, all done
>   echo '*** done'
> diff --git a/tests/qemu-iotests/tests/qemu-img-bitmaps.out b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
> index 17b34eaed30f..685bde6d1d63 100644
> --- a/tests/qemu-iotests/tests/qemu-img-bitmaps.out
> +++ b/tests/qemu-iotests/tests/qemu-img-bitmaps.out
> @@ -145,4 +145,18 @@ Format specific information:
>       corrupt: false
>   qemu-img: Failed to populate bitmap b0: Bitmap 'b0' is inconsistent and cannot be used
>   Try block-dirty-bitmap-remove to delete this bitmap from disk
> +qemu-img: warning: Skipping inconsistent bitmap b0
> +qemu-img: warning: Skipping inconsistent bitmap b2
> +image: TEST_DIR/t.IMGFMT.copy
> +file format: IMGFMT
> +virtual size: 10 MiB (10485760 bytes)
> +cluster_size: 65536
> +Format specific information:
> +    bitmaps:
> +        [0]:
> +            flags:
> +                [0]: auto
> +            name: b4
> +            granularity: 65536
> +    corrupt: false
>   *** done
> 


-- 
Best regards,
Vladimir

Re: [PATCH 0/2] Let 'qemu-img convert --bitmaps' skip inconsistent bitmaps

[Vladimir Sementsov-Ogievskiy]

08.07.2021 04:29, Eric Blake wrote:
> This is mostly a convenience factor as one could already use 'qemu-img
> info' to learn which bitmaps are broken and then 'qemu-img bitmap
> --remove' to nuke them before calling 'qemu-img convert --bitmaps',
> but it does have the advantage that the copied file is usable without
> extra efforts and the broken bitmap is not deleted from the source
> file.
> 
> Eric Blake (2):
>    iotests: Improve and rename test 291 to qemu-img-bitmap
>    qemu-img: Add --skip-broken for 'convert --bitmaps'
> 
>   docs/tools/qemu-img.rst                       |  8 +++-
>   block/dirty-bitmap.c                          |  2 +-
>   qemu-img.c                                    | 20 +++++++-
>   .../{291 => tests/qemu-img-bitmaps}           | 17 ++++++-
>   .../{291.out => tests/qemu-img-bitmaps.out}   | 46 ++++++++++++++++++-
>   5 files changed, 87 insertions(+), 6 deletions(-)
>   rename tests/qemu-iotests/{291 => tests/qemu-img-bitmaps} (88%)
>   rename tests/qemu-iotests/{291.out => tests/qemu-img-bitmaps.out} (76%)
> 

I've applied this onto your nbd branch. This doesn't apply on master.

-- 
Best regards,
Vladimir

Re: [PATCH 1/2] iotests: Improve and rename test 291 to qemu-img-bitmap

[Eric Blake]

On Fri, Jul 09, 2021 at 09:33:50AM +0300, Vladimir Sementsov-Ogievskiy wrote:
> > +++ b/tests/qemu-iotests/tests/qemu-img-bitmaps

> > +echo
> > +echo "=== Check handling of inconsistent bitmap ==="
> > +echo
> > +
> > +$QEMU_IO -c abort "$TEST_IMG" 2>/dev/null
> > +$QEMU_IMG bitmap --add "$TEST_IMG" b4
> > +$QEMU_IMG bitmap --remove "$TEST_IMG" b1
> > +_img_info --format-specific | _filter_irrelevant_img_info
> > +$QEMU_IMG convert --bitmaps -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
> 
> Worth then removing remaining inconsistent bitmaps and try again?
> 
> I think you should now remove $TEST_IMG.copy in _cleanup

$TEST_IMG.copy isn't created on failure (or if it is, that in itself
is a problem we should be avoiding), so as written, there was nothing
that should have needed cleaning up until patch 2.  But your idea
(here and in patch 2) of demonstrating manual cleanup for recovery (in
addition to the goal of patch 2 of skipping broken bitmaps in the
first place) is reasonable, so I'll incorporate that into v2.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Re: [PATCH 1/2] iotests: Improve and rename test 291 to qemu-img-bitmap

[Vladimir Sementsov-Ogievskiy]

09.07.2021 16:16, Eric Blake wrote:
> On Fri, Jul 09, 2021 at 09:33:50AM +0300, Vladimir Sementsov-Ogievskiy wrote:
>>> +++ b/tests/qemu-iotests/tests/qemu-img-bitmaps
> 
>>> +echo
>>> +echo "=== Check handling of inconsistent bitmap ==="
>>> +echo
>>> +
>>> +$QEMU_IO -c abort "$TEST_IMG" 2>/dev/null
>>> +$QEMU_IMG bitmap --add "$TEST_IMG" b4
>>> +$QEMU_IMG bitmap --remove "$TEST_IMG" b1
>>> +_img_info --format-specific | _filter_irrelevant_img_info
>>> +$QEMU_IMG convert --bitmaps -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
>>
>> Worth then removing remaining inconsistent bitmaps and try again?
>>
>> I think you should now remove $TEST_IMG.copy in _cleanup
> 
> $TEST_IMG.copy isn't created on failure (or if it is, that in itself
> is a problem we should be avoiding),

Seems that's the case:
./build/qemu-img create -f qcow2 x 1M
./build/qemu-img bitmap --add x b1
./build/qemu-io x
qemu-io> abort
Aborted (core dumped)
  ./build/qemu-img info x
image: x
file format: qcow2
virtual size: 1 MiB (1048576 bytes)
disk size: 204 KiB
cluster_size: 65536
Format specific information:
     compat: 1.1
     compression type: zlib
     lazy refcounts: false
     bitmaps:
         [0]:
             flags:
                 [0]: in-use
                 [1]: auto
             name: b1
             granularity: 65536
     refcount bits: 16
     corrupt: false
     extended l2: false


ls y
ls: cannot access 'y': No such file or directory
./build/qemu-img convert --bitmaps -O qcow2 x y
qemu-img: Failed to populate bitmap b1: Bitmap 'b1' is inconsistent and cannot be used
Try block-dirty-bitmap-remove to delete this bitmap from disk[root@kvm master]#
# ls y
y
./build/qemu-img info y
image: y
file format: qcow2
virtual size: 1 MiB (1048576 bytes)
disk size: 204 KiB
cluster_size: 65536
Format specific information:
     compat: 1.1
     compression type: zlib
     lazy refcounts: false
     bitmaps:
         [0]:
             flags:
             name: b1
             granularity: 65536
     refcount bits: 16
     corrupt: false
     extended l2: false


WOW! It even contains the bitmap not marked in-use. That's a real bug.

> so as written, there was nothing
> that should have needed cleaning up until patch 2.  But your idea
> (here and in patch 2) of demonstrating manual cleanup for recovery (in
> addition to the goal of patch 2 of skipping broken bitmaps in the
> first place) is reasonable, so I'll incorporate that into v2.
> 


-- 
Best regards,
Vladimir

Re: [PATCH 1/2] iotests: Improve and rename test 291 to qemu-img-bitmap

[Eric Blake]

On Fri, Jul 09, 2021 at 04:49:01PM +0300, Vladimir Sementsov-Ogievskiy wrote:
> 09.07.2021 16:16, Eric Blake wrote:
> > On Fri, Jul 09, 2021 at 09:33:50AM +0300, Vladimir Sementsov-Ogievskiy wrote:
> > > > +++ b/tests/qemu-iotests/tests/qemu-img-bitmaps
> > 
> > > > +echo
> > > > +echo "=== Check handling of inconsistent bitmap ==="
> > > > +echo
> > > > +
> > > > +$QEMU_IO -c abort "$TEST_IMG" 2>/dev/null
> > > > +$QEMU_IMG bitmap --add "$TEST_IMG" b4
> > > > +$QEMU_IMG bitmap --remove "$TEST_IMG" b1
> > > > +_img_info --format-specific | _filter_irrelevant_img_info
> > > > +$QEMU_IMG convert --bitmaps -O qcow2 "$TEST_IMG" "$TEST_IMG.copy"
> > > 
> > > Worth then removing remaining inconsistent bitmaps and try again?
> > > 
> > > I think you should now remove $TEST_IMG.copy in _cleanup
> > 
> > $TEST_IMG.copy isn't created on failure (or if it is, that in itself
> > is a problem we should be avoiding),
> 
> Seems that's the case:

Oh. Thanks for checking.  Yeah, re-reading the code, we don't attempt
to copy the bitmaps until after the rest of the convert operation is
done.  Which means a fix to pre-validate bitmaps before starting the
convert requires more code, but may be the right thing (failing at the
very end of a long convert attempt, but leaving the file around, is
not ideal compared to failing fast).

Looks like my v2 will be a bit more beefy.
> ./build/qemu-img convert --bitmaps -O qcow2 x y
> qemu-img: Failed to populate bitmap b1: Bitmap 'b1' is inconsistent and cannot be used
> Try block-dirty-bitmap-remove to delete this bitmap from disk[root@kvm master]#
> # ls y
> y
> ./build/qemu-img info y
> image: y
> file format: qcow2
> virtual size: 1 MiB (1048576 bytes)
> disk size: 204 KiB
> cluster_size: 65536
> Format specific information:
>     compat: 1.1
>     compression type: zlib
>     lazy refcounts: false
>     bitmaps:
>         [0]:
>             flags:
>             name: b1
>             granularity: 65536
>     refcount bits: 16
>     corrupt: false
>     extended l2: false
> 
> 
> WOW! It even contains the bitmap not marked in-use. That's a real bug.

So we left things dangling with a bitmap that has completely different
contents than in the original file.  Yeah, that looks like an issue
worth improving.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org