On 10/22/2014 09:57 AM, Max Reitz wrote: > As its comment states, raw_co_get_block_status() should unconditionally > return 0 and set *pnum to 0 for after EOF. > > An assertion after lseek(..., SEEK_HOLE) tried to catch this case by > asserting that errno != -ENXIO (which would indicate a position after > the EOF); but it should be errno != ENXIO instead. Regardless of that, > there should be no such assertion at all. If bdrv_getlength() returned > an outdated value and the image has been resized outside of qemu, > lseek() will return with errno == ENXIO. Just return that value as an > error then. > > Setting *pnum to 0 and returning 0 should not be done here, as in that > case we should update the device length as well. So, from qemu's > perspective, the file has not been resized; it's just that there was an > error querying sectors beyond a certain point (the actual file size). > > Additionally, nb_sectors should be clamped against the image end. This > was probably not an issue if FIEMAP or SEEK_HOLE/SEEK_DATA worked, but > the fallback did not take this case into account. > > Reported-by: Kevin Wolf <kw...@redhat.com> > Signed-off-by: Max Reitz <mre...@redhat.com> > --- > block/raw-posix.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-)
Reviewed-by: Eric Blake <ebl...@redhat.com>
> + if (total_size < 0) {
> + return total_size;
> + } else if (start >= total_size) {
> + *pnum = 0;
> + return 0;
> + } else if (start + nb_sectors * BDRV_SECTOR_SIZE > total_size) {
> + nb_sectors = (total_size - start) / BDRV_SECTOR_SIZE;
Should this round up instead of truncate? But it would only matter for
a file size that is not a multiple of sectors, where we probably have
other issues, and where reporting just the full sectors also seems
reasonable.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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