Message ID | cbd2d430e1eb75264289b243a7863f8ed6570ea2.1390513348.git.jcody@redhat.com |
---|---|
State | New |
Headers | show |
Le Thursday 23 Jan 2014 à 16:48:55 (-0500), Jeff Cody a écrit : > Currently, if an image file is logically larger than its backing file, > commiting it via 'qemu-img commit' will fail. > > For instance, if we have a base image with a virtual size 10G, and a > snapshot image of size 20G, then committing the snapshot offline with > 'qemu-img commit' will likely fail. > > This will automatically attempt to resize the base image, if the > snapshot image to be committed is larger. > > Signed-off-by: Jeff Cody <jcody@redhat.com> > Reviewed-by: Fam Zheng <famz@redhat.com> > Reviewed-by: Eric Blake <eblake@redhat.com> > --- > block.c | 23 ++++++++++++++++++++--- > 1 file changed, 20 insertions(+), 3 deletions(-) > > diff --git a/block.c b/block.c > index 64e7d22..dea7591 100644 > --- a/block.c > +++ b/block.c > @@ -1876,10 +1876,10 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix) > int bdrv_commit(BlockDriverState *bs) > { > BlockDriver *drv = bs->drv; > - int64_t sector, total_sectors; > + int64_t sector, total_sectors, length, backing_length; > int n, ro, open_flags; > int ret = 0; > - uint8_t *buf; > + uint8_t *buf = NULL; Why assign NULL to buf ? Is it related to the rest of the patch ? Reviewed-by: Benoit Canet <benoit@irqsave.net> > char filename[PATH_MAX]; > > if (!drv) > @@ -1904,7 +1904,24 @@ int bdrv_commit(BlockDriverState *bs) > } > } > > - total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; > + length = bdrv_getlength(bs); > + backing_length = bdrv_getlength(bs->backing_hd); > + > + if (length < 0 || backing_length < 0) { > + goto ro_cleanup; > + } > + > + /* If our top snapshot is larger than the backing file image, > + * grow the backing file image if possible. If not possible, > + * we must return an error */ > + if (length > backing_length) { > + ret = bdrv_truncate(bs->backing_hd, length); > + if (ret < 0) { > + goto ro_cleanup; > + } > + } > + > + total_sectors = length >> BDRV_SECTOR_BITS; > buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); > > for (sector = 0; sector < total_sectors; sector += n) { > -- > 1.8.3.1 > >
On 01/23/2014 03:00 PM, Benoît Canet wrote: > Le Thursday 23 Jan 2014 à 16:48:55 (-0500), Jeff Cody a écrit : >> Currently, if an image file is logically larger than its backing file, >> commiting it via 'qemu-img commit' will fail. s/commiting/committing/ >> + uint8_t *buf = NULL; > > Why assign NULL to buf ? Is it related to the rest of the patch ? > > Reviewed-by: Benoit Canet <benoit@irqsave.net> > >> char filename[PATH_MAX]; >> >> if (!drv) >> @@ -1904,7 +1904,24 @@ int bdrv_commit(BlockDriverState *bs) >> } >> } >> >> - total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; >> + length = bdrv_getlength(bs); >> + backing_length = bdrv_getlength(bs->backing_hd); >> + >> + if (length < 0 || backing_length < 0) { >> + goto ro_cleanup; Because this goto now reaches the ro_cleanup label with buf uninitialized, if we don't assign NULL originally. >> + total_sectors = length >> BDRV_SECTOR_BITS; >> buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); The old code only ever reached ro_cleanup after assigning buf, and ro_cleanup blindly frees buf.
On Thu, Jan 23, 2014 at 03:07:44PM -0700, Eric Blake wrote: > On 01/23/2014 03:00 PM, Benoît Canet wrote: > > Le Thursday 23 Jan 2014 à 16:48:55 (-0500), Jeff Cody a écrit : > >> Currently, if an image file is logically larger than its backing file, > >> commiting it via 'qemu-img commit' will fail. > > s/commiting/committing/ > I could respin, or Kevin / Stefan could fix this up whenever it is applied to their branches. > > >> + uint8_t *buf = NULL; > > > > Why assign NULL to buf ? Is it related to the rest of the patch ? > > > > Reviewed-by: Benoit Canet <benoit@irqsave.net> > > > >> char filename[PATH_MAX]; > >> > >> if (!drv) > >> @@ -1904,7 +1904,24 @@ int bdrv_commit(BlockDriverState *bs) > >> } > >> } > >> > >> - total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; > >> + length = bdrv_getlength(bs); > >> + backing_length = bdrv_getlength(bs->backing_hd); > >> + > >> + if (length < 0 || backing_length < 0) { > >> + goto ro_cleanup; > > Because this goto now reaches the ro_cleanup label with buf > uninitialized, if we don't assign NULL originally. > Yup, exactly. > >> + total_sectors = length >> BDRV_SECTOR_BITS; > >> buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); > > The old code only ever reached ro_cleanup after assigning buf, and > ro_cleanup blindly frees buf. > > -- > Eric Blake eblake redhat com +1-919-301-3266 > Libvirt virtualization library http://libvirt.org >
Le Thursday 23 Jan 2014 à 15:07:44 (-0700), Eric Blake a écrit : > On 01/23/2014 03:00 PM, Benoît Canet wrote: > > Le Thursday 23 Jan 2014 à 16:48:55 (-0500), Jeff Cody a écrit : > >> Currently, if an image file is logically larger than its backing file, > >> commiting it via 'qemu-img commit' will fail. > > s/commiting/committing/ > > > >> + uint8_t *buf = NULL; > > > > Why assign NULL to buf ? Is it related to the rest of the patch ? > > > > Reviewed-by: Benoit Canet <benoit@irqsave.net> > > > >> char filename[PATH_MAX]; > >> > >> if (!drv) > >> @@ -1904,7 +1904,24 @@ int bdrv_commit(BlockDriverState *bs) > >> } > >> } > >> > >> - total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; > >> + length = bdrv_getlength(bs); > >> + backing_length = bdrv_getlength(bs->backing_hd); > >> + > >> + if (length < 0 || backing_length < 0) { > >> + goto ro_cleanup; > > Because this goto now reaches the ro_cleanup label with buf > uninitialized, if we don't assign NULL originally. Thanks for the explanation. Best regards Benoît > > >> + total_sectors = length >> BDRV_SECTOR_BITS; > >> buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); > > The old code only ever reached ro_cleanup after assigning buf, and > ro_cleanup blindly frees buf. > > -- > Eric Blake eblake redhat com +1-919-301-3266 > Libvirt virtualization library http://libvirt.org >
diff --git a/block.c b/block.c index 64e7d22..dea7591 100644 --- a/block.c +++ b/block.c @@ -1876,10 +1876,10 @@ int bdrv_check(BlockDriverState *bs, BdrvCheckResult *res, BdrvCheckMode fix) int bdrv_commit(BlockDriverState *bs) { BlockDriver *drv = bs->drv; - int64_t sector, total_sectors; + int64_t sector, total_sectors, length, backing_length; int n, ro, open_flags; int ret = 0; - uint8_t *buf; + uint8_t *buf = NULL; char filename[PATH_MAX]; if (!drv) @@ -1904,7 +1904,24 @@ int bdrv_commit(BlockDriverState *bs) } } - total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; + length = bdrv_getlength(bs); + backing_length = bdrv_getlength(bs->backing_hd); + + if (length < 0 || backing_length < 0) { + goto ro_cleanup; + } + + /* If our top snapshot is larger than the backing file image, + * grow the backing file image if possible. If not possible, + * we must return an error */ + if (length > backing_length) { + ret = bdrv_truncate(bs->backing_hd, length); + if (ret < 0) { + goto ro_cleanup; + } + } + + total_sectors = length >> BDRV_SECTOR_BITS; buf = g_malloc(COMMIT_BUF_SECTORS * BDRV_SECTOR_SIZE); for (sector = 0; sector < total_sectors; sector += n) {