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Re: [PATCH v5 4/5] qemu-img: Add convert --bitmaps option
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From: |
Nir Soffer |
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Subject: |
Re: [PATCH v5 4/5] qemu-img: Add convert --bitmaps option |
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Date: |
Thu, 21 May 2020 18:11:07 +0300 |
On Thu, May 21, 2020 at 1:01 AM Eric Blake <address@hidden> wrote:
>
> Make it easier to copy all the persistent bitmaps of (the top layer
> of) a source image along with its guest-visible contents, by adding a
> boolean flag for use with qemu-img convert. This is basically
> shorthand, as the same effect could be accomplished with a series of
> 'qemu-img bitmap --add' and 'qemu-img bitmap --merge -b source'
> commands, or by QMP commands.
>
> Note that this command will fail in the same scenarios where 'qemu-img
> measure --bitmaps' fails, when either the source or the destanation
> lacks persistent bitmap support altogether.
If we remove --bitmaps option from qemu-img measure, we need to remove
this note.
>
> See also https://bugzilla.redhat.com/show_bug.cgi?id=1779893
>
> While touching this, clean up a couple coding issues spotted in the
> same function: an extra blank line, and merging back-to-back 'if
> (!skip_create)' blocks.
>
> Signed-off-by: Eric Blake <address@hidden>
> Message-Id: <address@hidden>
> ---
> docs/tools/qemu-img.rst | 6 +++-
> qemu-img.c | 77 +++++++++++++++++++++++++++++++++++++++--
> qemu-img-cmds.hx | 4 +--
> 3 files changed, 81 insertions(+), 6 deletions(-)
>
> diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
> index 9a8112fc9f58..35050fc51070 100644
> --- a/docs/tools/qemu-img.rst
> +++ b/docs/tools/qemu-img.rst
> @@ -162,6 +162,10 @@ Parameters to convert subcommand:
>
> .. program:: qemu-img-convert
>
> +.. option:: --bitmaps
> +
> + Additionally copy all persistent bitmaps from the top layer of the source
> +
> .. option:: -n
>
> Skip the creation of the target volume
> @@ -397,7 +401,7 @@ Command description:
> 4
> Error on reading data
>
> -.. option:: convert [--object OBJECTDEF] [--image-opts]
> [--target-image-opts] [--target-is-zero] [-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] [-m NUM_COROUTINES] [-W] FILENAME
> [FILENAME2 [...]] OUTPUT_FILENAME
> +.. 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] [-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
> diff --git a/qemu-img.c b/qemu-img.c
> index c1bafb57023a..1494d8f5c409 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -192,6 +192,7 @@ static void QEMU_NORETURN help(void)
> " hiding corruption that has already occurred.\n"
> "\n"
> "Parameters to convert subcommand:\n"
> + " '--bitmaps' copies all top-level persistent bitmaps to
> destination\n"
> " '-m' specifies how many coroutines work in parallel during the
> convert\n"
> " process (defaults to 8)\n"
> " '-W' allow to write to the target out of order rather than
> sequential\n"
> @@ -2139,6 +2140,39 @@ static int convert_do_copy(ImgConvertState *s)
> return s->ret;
> }
>
> +static int convert_copy_bitmaps(BlockDriverState *src, BlockDriverState *dst)
> +{
> + BdrvDirtyBitmap *bm;
> + Error *err = NULL;
> +
> + FOR_EACH_DIRTY_BITMAP(src, bm) {
> + const char *name;
> +
> + if (!bdrv_dirty_bitmap_get_persistence(bm)) {
> + continue;
> + }
> + name = bdrv_dirty_bitmap_name(bm);
> + qmp_block_dirty_bitmap_add(dst->node_name, name,
> + true, bdrv_dirty_bitmap_granularity(bm),
> + true, true,
> + true, !bdrv_dirty_bitmap_enabled(bm),
> + &err);
> + if (err) {
> + error_reportf_err(err, "Failed to create bitmap %s: ", name);
> + return -1;
> + }
> +
> + do_dirty_bitmap_merge(dst->node_name, name, src->node_name, name,
> + &err);
> + if (err) {
> + error_reportf_err(err, "Failed to populate bitmap %s: ", name);
> + return -1;
> + }
> + }
> +
> + return 0;
> +}
> +
> #define MAX_BUF_SECTORS 32768
>
> static int img_convert(int argc, char **argv)
> @@ -2160,6 +2194,8 @@ static int img_convert(int argc, char **argv)
> int64_t ret = -EINVAL;
> bool force_share = false;
> bool explict_min_sparse = false;
> + bool bitmaps = false;
> + size_t nbitmaps = 0;
>
> ImgConvertState s = (ImgConvertState) {
> /* Need at least 4k of zeros for sparse detection */
> @@ -2179,6 +2215,7 @@ static int img_convert(int argc, char **argv)
> {"target-image-opts", no_argument, 0, OPTION_TARGET_IMAGE_OPTS},
> {"salvage", no_argument, 0, OPTION_SALVAGE},
> {"target-is-zero", no_argument, 0, OPTION_TARGET_IS_ZERO},
> + {"bitmaps", no_argument, 0, OPTION_BITMAPS},
> {0, 0, 0, 0}
> };
> c = getopt_long(argc, argv, ":hf:O:B:Cco:l:S:pt:T:qnm:WU",
> @@ -2304,6 +2341,9 @@ static int img_convert(int argc, char **argv)
> */
> s.has_zero_init = true;
> break;
> + case OPTION_BITMAPS:
> + bitmaps = true;
> + break;
> }
> }
>
> @@ -2365,7 +2405,6 @@ static int img_convert(int argc, char **argv)
> goto fail_getopt;
> }
>
> -
> /* ret is still -EINVAL until here */
> ret = bdrv_parse_cache_mode(src_cache, &src_flags, &src_writethrough);
> if (ret < 0) {
> @@ -2525,6 +2564,27 @@ static int img_convert(int argc, char **argv)
> }
> }
>
> + /* Determine how many bitmaps need copying */
> + if (bitmaps) {
> + BdrvDirtyBitmap *bm;
> +
> + if (s.src_num > 1) {
> + error_report("Copying bitmaps only possible with single source");
> + ret = -1;
> + goto out;
> + }
> + if (!bdrv_supports_persistent_dirty_bitmap(blk_bs(s.src[0]))) {
> + error_report("Source lacks bitmap support");
> + ret = -1;
> + goto out;
> + }
> + FOR_EACH_DIRTY_BITMAP(blk_bs(s.src[0]), bm) {
> + if (bdrv_dirty_bitmap_get_persistence(bm)) {
> + nbitmaps++;
> + }
> + }
> + }
> +
> /*
> * The later open call will need any decryption secrets, and
> * bdrv_create() will purge "opts", so extract them now before
> @@ -2533,9 +2593,7 @@ static int img_convert(int argc, char **argv)
> if (!skip_create) {
> open_opts = qdict_new();
> qemu_opt_foreach(opts, img_add_key_secrets, open_opts, &error_abort);
> - }
>
> - if (!skip_create) {
> /* Create the new image */
> ret = bdrv_create(drv, out_filename, opts, &local_err);
> if (ret < 0) {
> @@ -2573,6 +2631,13 @@ static int img_convert(int argc, char **argv)
> }
> out_bs = blk_bs(s.target);
>
> + if (nbitmaps > 0 && !bdrv_supports_persistent_dirty_bitmap(out_bs)) {
> + error_report("Format driver '%s' does not support bitmaps",
> + out_fmt);
> + ret = -1;
> + goto out;
> + }
> +
> if (s.compressed && !block_driver_can_compress(out_bs->drv)) {
> error_report("Compression not supported for this file format");
> ret = -1;
> @@ -2632,6 +2697,12 @@ static int img_convert(int argc, char **argv)
> }
>
> ret = convert_do_copy(&s);
> +
> + /* Now copy the bitmaps */
> + if (nbitmaps > 0 && ret == 0) {
> + ret = convert_copy_bitmaps(blk_bs(s.src[0]), out_bs);
> + }
> +
> out:
> if (!ret) {
> qemu_progress_print(100, 0);
> diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
> index 235cc5fffadc..e9beb15e614e 100644
> --- a/qemu-img-cmds.hx
> +++ b/qemu-img-cmds.hx
> @@ -46,9 +46,9 @@ SRST
> ERST
>
> DEF("convert", img_convert,
> - "convert [--object objectdef] [--image-opts] [--target-image-opts]
> [--target-is-zero] [-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] [-m num_coroutines] [-W] [--salvage] filename [filename2
> [...]] output_filename")
> + "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] [-m num_coroutines] [-W] [--salvage]
> filename [filename2 [...]] output_filename")
> SRST
> -.. option:: convert [--object OBJECTDEF] [--image-opts]
> [--target-image-opts] [--target-is-zero] [-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] [-m NUM_COROUTINES] [-W] [--salvage]
> FILENAME [FILENAME2 [...]] OUTPUT_FILENAME
> +.. 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] [-m NUM_COROUTINES] [-W]
> [--salvage] FILENAME [FILENAME2 [...]] OUTPUT_FILENAME
> ERST
>
> DEF("create", img_create,
> --
> 2.26.2
>