With bash 5.1, the output of the following script changes:
a=("double space")
a=${a[@]:0:1}
echo "$a"
from "double space" to "double space", i.e. all white space is
preserved as-is. This is probably what we actually want here (judging
from the "...to accommodate pathnames with spaces" comment), but before
5.1, we would have to quote the ${} slice to get the same behavior.
In any case, without quoting, the reference output of many iotests is
different between bash 5.1 and pre-5.1, which is not very good. The
output of 5.1 is what we want, so whatever we do to get pre-5.1 to the
same result, it means we have to fix the reference output of basically
all tests that invoke _send_qemu_cmd (except the ones that only use
single spaces in the commands they invoke).
Instead of quoting the ${} slice (cmd="${$@: 1:...}"), we can also just
not use array slicing and replace the whole thing with a simple "cmd=$1;
shift", which works because all callers quote the whole $cmd argument
anyway.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20201217153803.101231-3-mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
This simply calls bdrv_co_pwrite_zeroes() in all children.
bs->supported_zero_flags is also set to the flags that are supported
by all children.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-Id: <2f09c842781fe336b4c2e40036bba577b7430190.1605286097.git.berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
The quorum driver does not implement bdrv_co_block_status() and
because of that it always reports to contain data even if all its
children are known to be empty.
One consequence of this is that if we for example create a quorum with
a size of 10GB and we mirror it to a new image the operation will
write 10GB of actual zeroes to the destination image wasting a lot of
time and disk space.
Since a quorum has an arbitrary number of children of potentially
different formats there is no way to report all possible allocation
status flags in a way that makes sense, so this implementation only
reports when a given region is known to contain zeroes
(BDRV_BLOCK_ZERO) or not (BDRV_BLOCK_DATA).
If all children agree that a region contains zeroes then we can return
BDRV_BLOCK_ZERO using the smallest size reported by the children
(because all agree that a region of at least that size contains
zeroes).
If at least one child disagrees we have to return BDRV_BLOCK_DATA.
In this case we use the largest of the sizes reported by the children
that didn't return BDRV_BLOCK_ZERO (because we know that there won't
be an agreement for at least that size).
Signed-off-by: Alberto Garcia <berto@igalia.com>
Tested-by: Tao Xu <tao3.xu@intel.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <db83149afcf0f793effc8878089d29af4c46ffe1.1605286097.git.berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
