Let's detect block-size automatically if not specified by user:
If both files define cluster-size, use minimum to be more precise.
If both files don't specify cluster-size, use default of 64K
If only one file specify cluster-size, just use it.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
docs/tools/qemu-img.rst | 7 +++-
qemu-img.c | 71 +++++++++++++++++++++++++++++++++++++----
qemu-img-cmds.hx | 4 +--
3 files changed, 72 insertions(+), 10 deletions(-)
diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst
index 8b6b799dd4..9bfdd93d6c 100644
--- a/docs/tools/qemu-img.rst
+++ b/docs/tools/qemu-img.rst
@@ -170,6 +170,11 @@ Parameters to compare subcommand:
Block size for comparing with ``--stat``. This doesn't guarantee an
exact size for comparing chunks, but it does guarantee that those
chunks will never cross a block-size-aligned boundary.
+ When unspecified the following logic is used:
+
+ - If both files define cluster-size, use minimum to be more precise.
+ - If both files don't specify cluster-size, use default of 64K
+ - If only one file specifies cluster-size, just use that.
Parameters to convert subcommand:
@@ -390,7 +395,7 @@ Command description:
The rate limit for the commit process is specified by ``-r``.
-.. option:: compare [--object OBJECTDEF] [--image-opts] [-f FMT] [-F FMT] [-T
SRC_CACHE] [-p] [-q] [-s] [-U] [--stat --block-size BLOCK_SIZE] FILENAME1
FILENAME2
+.. option:: compare [--object OBJECTDEF] [--image-opts] [-f FMT] [-F FMT] [-T
SRC_CACHE] [-p] [-q] [-s] [-U] [--stat [--block-size BLOCK_SIZE]] FILENAME1
FILENAME2
Check if two images have the same content. You can compare images with
different format or settings.
diff --git a/qemu-img.c b/qemu-img.c
index 0cb7cebe91..905150671f 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1407,6 +1407,62 @@ static void cmp_stat_print(ImgCmpStat *stat, int64_t
total_bytes)
}
}
+/* Get default value for qemu-img compare --block-size option. */
+static int img_compare_block_size(BlockDriverState *bs1,
+ BlockDriverState *bs2,
+ bool quiet)
+{
+ const int default_block_size = 64 * 1024; /* 64K */
+
+ int ret;
+ BlockDriverInfo bdi;
+ int cluster_size1, cluster_size2, block_size;
+ const char *note = "Note: to alter it, set --block-size option.";
+ const char *fname1 = bs1->filename;
+ const char *fname2 = bs2->filename;
+
+ ret = bdrv_get_info(bs1, &bdi);
+ if (ret < 0 && ret != -ENOTSUP) {
+ error_report("Failed to get info of %s: %s", fname1, strerror(-ret));
+ return ret;
+ }
+ cluster_size1 = ret < 0 ? 0 : bdi.cluster_size;
+
+ ret = bdrv_get_info(bs2, &bdi);
+ if (ret < 0 && ret != -ENOTSUP) {
+ error_report("Failed to get info of %s: %s", fname2, strerror(-ret));
+ return ret;
+ }
+ cluster_size2 = ret < 0 ? 0 : bdi.cluster_size;
+
+ if (cluster_size1 > 0 && cluster_size2 > 0) {
+ if (cluster_size1 == cluster_size2) {
+ block_size = cluster_size1;
+ } else {
+ block_size = MIN(cluster_size1, cluster_size2);
+ qprintf(quiet, "%s and %s have different cluster sizes: %d and %d "
+ "respectively. Using minimum as block-size for "
+ "accuracy: %d. %s\n",
+ fname1, fname2, cluster_size1,
+ cluster_size2, block_size, note);
+ }
+ } else if (cluster_size1 == 0 && cluster_size2 == 0) {
+ block_size = default_block_size;
+ qprintf(quiet, "Neither of %s and %s have an explicit cluster size. "
+ "Using default of %d bytes. %s\n", fname1, fname2, block_size,
+ note);
+ } else {
+ block_size = MAX(cluster_size1, cluster_size2);
+ qprintf(quiet, "%s has an explicit cluster size of %d and %s "
+ "doesn't have one. Using %d as block-size. %s\n",
+ cluster_size1 ? fname1 : fname2, block_size,
+ cluster_size1 ? fname2 : fname1,
+ block_size, note);
+ }
+
+ return block_size;
+}
+
/*
* Compares two images. Exit codes:
*
@@ -1534,13 +1590,6 @@ static int img_compare(int argc, char **argv)
goto out3;
}
- if (stat && !block_size) {
- /* TODO: make block-size optional */
- error_report("You must specify --block-size together with --stat");
- ret = 2;
- goto out3;
- }
-
if (stat && strict) {
error_report("--stat can't be used together with -s");
ret = 2;
@@ -1593,6 +1642,14 @@ static int img_compare(int argc, char **argv)
total_size = MIN(total_size1, total_size2);
progress_base = MAX(total_size1, total_size2);
+ if (stat && !block_size) {
+ block_size = img_compare_block_size(bs1, bs2, quiet);
+ if (block_size <= 0) {
+ ret = 4;
+ goto out;
+ }
+ }
+
qemu_progress_print(0, 100);
if (strict && total_size1 != total_size2) {
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index 0b2d63ca5f..96a193eea8 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -40,9 +40,9 @@ SRST
ERST
DEF("compare", img_compare,
- "compare [--object objectdef] [--image-opts] [-f fmt] [-F fmt] [-T
src_cache] [-p] [-q] [-s] [-U] [--stat --block-size BLOCK_SIZE] filename1
filename2")
+ "compare [--object objectdef] [--image-opts] [-f fmt] [-F fmt] [-T
src_cache] [-p] [-q] [-s] [-U] [--stat [--block-size BLOCK_SIZE]] filename1
filename2")
SRST
-.. option:: compare [--object OBJECTDEF] [--image-opts] [-f FMT] [-F FMT] [-T
SRC_CACHE] [-p] [-q] [-s] [-U] [--stat --block-size BLOCK_SIZE] FILENAME1
FILENAME2
+.. option:: compare [--object OBJECTDEF] [--image-opts] [-f FMT] [-F FMT] [-T
SRC_CACHE] [-p] [-q] [-s] [-U] [--stat [--block-size BLOCK_SIZE]] FILENAME1
FILENAME2
ERST
DEF("convert", img_convert,
--
2.31.1
