On 10/15/2012 02:50 PM, Alex Bligh wrote: > 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-img rebase > already supports this when '-u' is used; this adds support when -u is not > used. > > Signed-off-by: Alex Bligh <a...@alex.org.uk> > --- > qemu-img.c | 26 ++++++++++++++++---------- > qemu-img.texi | 4 +++- > 2 files changed, 19 insertions(+), 11 deletions(-)
Per http://wiki.qemu.org/Contribute/SubmitAPatch, it helps to add a maintainer in cc; I'm guessing that this is most closely related to block work, and therefore adding Kevin in cc. Reviewed-by: Eric Blake <ebl...@redhat.com> > > Also obtainable from: > https://github.com/abligh/qemu.git > Commit at: > > https://github.com/abligh/qemu/commit/49cd454aa09062b151710cc7afd4bb7fcf1070d0 > > diff --git a/qemu-img.c b/qemu-img.c > index f17f187..e817498 100644 > --- a/qemu-img.c > +++ b/qemu-img.c > @@ -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); > diff --git a/qemu-img.texi b/qemu-img.texi > index 8b05f2c..42ec392 100644 > --- a/qemu-img.texi > +++ b/qemu-img.texi > @@ -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 > -- Eric Blake ebl...@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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