@@ -1558,13 +1558,14 @@ static int img_rebase(int argc, char **argv)
error_report("Could not open old backing file '%s'", backing_name);
goto out;
}
-
- bs_new_backing = bdrv_new("new_backing");
- ret = bdrv_open(bs_new_backing, out_baseimg, BDRV_O_FLAGS,
+ if (out_baseimg[0]) {
+ bs_new_backing = bdrv_new("new_backing");
+ ret = bdrv_open(bs_new_backing, out_baseimg, BDRV_O_FLAGS,
new_backing_drv);
- if (ret) {
- error_report("Could not open new backing file '%s'", out_baseimg);
- goto out;
+ if (ret) {
+ error_report("Could not open new backing file '%s'", out_baseimg);
+ goto out;
+ }
}
}
@@ -1580,7 +1581,7 @@ static int img_rebase(int argc, char **argv)
if (!unsafe) {
uint64_t num_sectors;
uint64_t old_backing_num_sectors;
- uint64_t new_backing_num_sectors;
+ uint64_t new_backing_num_sectors = 0;
uint64_t sector;
int n;
uint8_t * buf_old;
@@ -1592,7 +1593,8 @@ static int img_rebase(int argc, char **argv)
bdrv_get_geometry(bs, &num_sectors);
bdrv_get_geometry(bs_old_backing, &old_backing_num_sectors);
- bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors);
+ if (bs_new_backing)
+ bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors);
local_progress = (float)100 /
(num_sectors / MIN(num_sectors, IO_BUF_SIZE / 512));
@@ -1629,7 +1631,7 @@ static int img_rebase(int argc, char **argv)
}
}
- if (sector >= new_backing_num_sectors) {
+ if (sector >= new_backing_num_sectors || !bs_new_backing) {
memset(buf_new, 0, n * BDRV_SECTOR_SIZE);
} else {
if (sector + n > new_backing_num_sectors) {
@@ -1675,7 +1677,11 @@ static int img_rebase(int argc, char **argv)
* backing file are overwritten in the COW file now, so the visible content
* doesn't change when we switch the backing file.
*/
- ret = bdrv_change_backing_file(bs, out_baseimg, out_basefmt);
+ if (bs_new_backing)
+ ret = bdrv_change_backing_file(bs, out_baseimg, out_basefmt);
+ else
+ ret = bdrv_change_backing_file(bs, NULL, NULL);
+
if (ret == -ENOSPC) {
error_report("Could not change the backing file to '%s': No "
"space left in the file header", out_baseimg);
@@ -148,7 +148,9 @@ Changes the backing file of an image. Only the formats @code{qcow2} and
The backing file is changed to @var{backing_file} and (if the image format of
@var{filename} supports this) the backing file format is changed to
-@var{backing_fmt}.
+@var{backing_fmt}. If @var{backing_file} is specified as ``'' (the empty
+string), then the image is rebased onto no backing file (i.e. it will exist
+independently of any backing file).
There are two different modes in which @code{rebase} can operate:
@table @option
This patch allows an empty filename to be passed as the new base image name for qemu-img rebase to mean base the image on no backing file (i.e. independent of any backing file). According to Eric Blake, qemu-imag rebase already supports this when '-u' is used; this adds support when -u is not used. Signed-off-by: Alex Bligh <alex@alex.org.uk> --- qemu-img.c | 26 ++++++++++++++++---------- qemu-img.texi | 4 +++- 2 files changed, 19 insertions(+), 11 deletions(-) Also obtainable from: https://github.com/abligh/qemu.git Commit at: https://github.com/abligh/qemu/commit/49cd454aa09062b151710cc7afd4bb7fcf1070d0