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authorPavel Butsykin <pbutsykin@virtuozzo.com>2017-09-18 15:42:27 +0300
committerMax Reitz <mreitz@redhat.com>2017-09-26 15:00:32 +0200
commit4ffca8904a350460cdaa6304ea8c9b9c693d2d91 (patch)
tree3d7c0d764d18334222c11e84dc8a081361ada1b6
parent69ff158b677df0862b2f2639740c8fda5eb91599 (diff)
downloadqemu-arm-4ffca8904a350460cdaa6304ea8c9b9c693d2d91.tar.gz
qemu-img: add --shrink flag for resize
The flag is additional precaution against data loss. Perhaps in the future the operation shrink without this flag will be blocked for all formats, but for now we need to maintain compatibility with raw. Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 20170918124230.8152-2-pbutsykin@virtuozzo.com [mreitz: Added a missing space to a warning] Signed-off-by: Max Reitz <mreitz@redhat.com>
-rw-r--r--qemu-img-cmds.hx4
-rw-r--r--qemu-img.c23
-rw-r--r--qemu-img.texi6
-rwxr-xr-xtests/qemu-iotests/1024
-rwxr-xr-xtests/qemu-iotests/1062
5 files changed, 33 insertions, 6 deletions
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index b47d409665..2fe31893cf 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -89,9 +89,9 @@ STEXI
ETEXI
DEF("resize", img_resize,
- "resize [--object objectdef] [--image-opts] [-q] filename [+ | -]size")
+ "resize [--object objectdef] [--image-opts] [-q] [--shrink] filename [+ | -]size")
STEXI
-@item resize [--object @var{objectdef}] [--image-opts] [-q] @var{filename} [+ | -]@var{size}
+@item resize [--object @var{objectdef}] [--image-opts] [-q] [--shrink] @var{filename} [+ | -]@var{size}
ETEXI
STEXI
diff --git a/qemu-img.c b/qemu-img.c
index df984b11b9..d6007b2a6d 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -64,6 +64,7 @@ enum {
OPTION_TARGET_IMAGE_OPTS = 263,
OPTION_SIZE = 264,
OPTION_PREALLOCATION = 265,
+ OPTION_SHRINK = 266,
};
typedef enum OutputFormat {
@@ -3436,6 +3437,7 @@ static int img_resize(int argc, char **argv)
},
};
bool image_opts = false;
+ bool shrink = false;
/* Remove size from argv manually so that negative numbers are not treated
* as options by getopt. */
@@ -3454,6 +3456,7 @@ static int img_resize(int argc, char **argv)
{"object", required_argument, 0, OPTION_OBJECT},
{"image-opts", no_argument, 0, OPTION_IMAGE_OPTS},
{"preallocation", required_argument, 0, OPTION_PREALLOCATION},
+ {"shrink", no_argument, 0, OPTION_SHRINK},
{0, 0, 0, 0}
};
c = getopt_long(argc, argv, ":f:hq",
@@ -3496,6 +3499,9 @@ static int img_resize(int argc, char **argv)
return 1;
}
break;
+ case OPTION_SHRINK:
+ shrink = true;
+ break;
}
}
if (optind != argc - 1) {
@@ -3569,6 +3575,23 @@ static int img_resize(int argc, char **argv)
goto out;
}
+ if (total_size < current_size && !shrink) {
+ warn_report("Shrinking an image will delete all data beyond the "
+ "shrunken image's end. Before performing such an "
+ "operation, make sure there is no important data there.");
+
+ if (g_strcmp0(bdrv_get_format_name(blk_bs(blk)), "raw") != 0) {
+ error_report(
+ "Use the --shrink option to perform a shrink operation.");
+ ret = -1;
+ goto out;
+ } else {
+ warn_report("Using the --shrink option will suppress this message. "
+ "Note that future versions of qemu-img may refuse to "
+ "shrink images without this option.");
+ }
+ }
+
ret = blk_truncate(blk, total_size, prealloc, &err);
if (!ret) {
qprintf(quiet, "Image resized.\n");
diff --git a/qemu-img.texi b/qemu-img.texi
index 90c7eab4a8..ee5c5940d3 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -545,7 +545,7 @@ qemu-img rebase -b base.img diff.qcow2
At this point, @code{modified.img} can be discarded, since
@code{base.img + diff.qcow2} contains the same information.
-@item resize [--preallocation=@var{prealloc}] @var{filename} [+ | -]@var{size}
+@item resize [--shrink] [--preallocation=@var{prealloc}] @var{filename} [+ | -]@var{size}
Change the disk image as if it had been created with @var{size}.
@@ -553,6 +553,10 @@ Before using this command to shrink a disk image, you MUST use file system and
partitioning tools inside the VM to reduce allocated file systems and partition
sizes accordingly. Failure to do so will result in data loss!
+When shrinking images, the @code{--shrink} option must be given. This informs
+qemu-img that the user acknowledges all loss of data beyond the truncated
+image's end.
+
After using this command to grow a disk image, you must use file system and
partitioning tools inside the VM to actually begin using the new space on the
device.
diff --git a/tests/qemu-iotests/102 b/tests/qemu-iotests/102
index 87db1bb1bf..d7ad8d9840 100755
--- a/tests/qemu-iotests/102
+++ b/tests/qemu-iotests/102
@@ -54,7 +54,7 @@ _make_test_img $IMG_SIZE
$QEMU_IO -c 'write 0 64k' "$TEST_IMG" | _filter_qemu_io
# Remove data cluster from image (first cluster: image header, second: reftable,
# third: refblock, fourth: L1 table, fifth: L2 table)
-$QEMU_IMG resize -f raw "$TEST_IMG" $((5 * 64 * 1024))
+$QEMU_IMG resize -f raw --shrink "$TEST_IMG" $((5 * 64 * 1024))
$QEMU_IO -c map "$TEST_IMG"
$QEMU_IMG map "$TEST_IMG"
@@ -69,7 +69,7 @@ $QEMU_IO -c 'write 0 64k' "$TEST_IMG" | _filter_qemu_io
qemu_comm_method=monitor _launch_qemu -drive if=none,file="$TEST_IMG",id=drv0
-$QEMU_IMG resize -f raw "$TEST_IMG" $((5 * 64 * 1024))
+$QEMU_IMG resize -f raw --shrink "$TEST_IMG" $((5 * 64 * 1024))
_send_qemu_cmd $QEMU_HANDLE 'qemu-io drv0 map' 'allocated' \
| sed -e 's/^(qemu).*qemu-io drv0 map...$/(qemu) qemu-io drv0 map/'
diff --git a/tests/qemu-iotests/106 b/tests/qemu-iotests/106
index 32649578fb..bfe71f4e60 100755
--- a/tests/qemu-iotests/106
+++ b/tests/qemu-iotests/106
@@ -83,7 +83,7 @@ echo '=== Testing image shrinking ==='
for growth_mode in falloc full off; do
echo
echo "--- growth_mode=$growth_mode ---"
- $QEMU_IMG resize -f "$IMGFMT" --preallocation=$growth_mode "$TEST_IMG" -${GROWTH_SIZE}K
+ $QEMU_IMG resize -f "$IMGFMT" --shrink --preallocation=$growth_mode "$TEST_IMG" -${GROWTH_SIZE}K
done
# success, all done