The assertion is currently failing. We can't require callers to have
write permissions when all they are doing is a read, so comment it out.
Add a FIXME comment in the code so that the check is re-enabled when
copy on read is refactored into its own filter driver.
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
block/io.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/block/io.c b/block/io.c
index 2709a70..7321dda 100644
--- a/block/io.c
+++ b/block/io.c
@@ -945,7 +945,14 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child,
size_t skip_bytes;
int ret;
- assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
+ /* FIXME We cannot require callers to have write permissions when all they
+ * are doing is a read request. If we did things right, write permissions
+ * would be obtained anyway, but internally by the copy-on-read code. As
+ * long as it is implemented here rather than in a separat filter driver,
+ * the copy-on-read code doesn't have its own BdrvChild, however, for which
+ * it could request permissions. Therefore we have to bypass the permission
+ * system for the moment. */
+ // assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE));
/* Cover entire cluster so no additional backing file I/O is required when
* allocating cluster in the image file.
--
1.8.3.1
On Fri, Apr 07, 2017 at 12:32:45PM +0200, Kevin Wolf wrote: > The assertion is currently failing. We can't require callers to have > write permissions when all they are doing is a read, so comment it out. > Add a FIXME comment in the code so that the check is re-enabled when > copy on read is refactored into its own filter driver. > > Reported-by: Richard W.M. Jones <rjones@redhat.com> > Signed-off-by: Kevin Wolf <kwolf@redhat.com> Thanks Kevin. As this is essentially the same as the patch I tested last night, Reviewed-by: Richard W.M. Jones <rjones@redhat.com> Rich. > block/io.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/block/io.c b/block/io.c > index 2709a70..7321dda 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -945,7 +945,14 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child, > size_t skip_bytes; > int ret; > > - assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); > + /* FIXME We cannot require callers to have write permissions when all they > + * are doing is a read request. If we did things right, write permissions > + * would be obtained anyway, but internally by the copy-on-read code. As > + * long as it is implemented here rather than in a separat filter driver, > + * the copy-on-read code doesn't have its own BdrvChild, however, for which > + * it could request permissions. Therefore we have to bypass the permission > + * system for the moment. */ > + // assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); > > /* Cover entire cluster so no additional backing file I/O is required when > * allocating cluster in the image file. > -- > 1.8.3.1 -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html
On 04/07/2017 05:32 AM, Kevin Wolf wrote: > The assertion is currently failing. We can't require callers to have > write permissions when all they are doing is a read, so comment it out. > Add a FIXME comment in the code so that the check is re-enabled when > copy on read is refactored into its own filter driver. > > Reported-by: Richard W.M. Jones <rjones@redhat.com> > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > --- > block/io.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/block/io.c b/block/io.c > index 2709a70..7321dda 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -945,7 +945,14 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child, > size_t skip_bytes; > int ret; > > - assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); > + /* FIXME We cannot require callers to have write permissions when all they > + * are doing is a read request. If we did things right, write permissions > + * would be obtained anyway, but internally by the copy-on-read code. As > + * long as it is implemented here rather than in a separat filter driver, s/separat/separate/ > + * the copy-on-read code doesn't have its own BdrvChild, however, for which > + * it could request permissions. Therefore we have to bypass the permission > + * system for the moment. */ > + // assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); Makes checkpatch.pl unhappy - but that's intentional. Reviewed-by: Eric Blake <eblake@redhat.com> -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
On 07.04.2017 15:53, Eric Blake wrote: > On 04/07/2017 05:32 AM, Kevin Wolf wrote: >> The assertion is currently failing. We can't require callers to have >> write permissions when all they are doing is a read, so comment it out. >> Add a FIXME comment in the code so that the check is re-enabled when >> copy on read is refactored into its own filter driver. >> >> Reported-by: Richard W.M. Jones <rjones@redhat.com> >> Signed-off-by: Kevin Wolf <kwolf@redhat.com> >> --- >> block/io.c | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/block/io.c b/block/io.c >> index 2709a70..7321dda 100644 >> --- a/block/io.c >> +++ b/block/io.c >> @@ -945,7 +945,14 @@ static int coroutine_fn bdrv_co_do_copy_on_readv(BdrvChild *child, >> size_t skip_bytes; >> int ret; >> >> - assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); >> + /* FIXME We cannot require callers to have write permissions when all they >> + * are doing is a read request. If we did things right, write permissions >> + * would be obtained anyway, but internally by the copy-on-read code. As >> + * long as it is implemented here rather than in a separat filter driver, > > s/separat/separate/ > >> + * the copy-on-read code doesn't have its own BdrvChild, however, for which >> + * it could request permissions. Therefore we have to bypass the permission >> + * system for the moment. */ >> + // assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); > > Makes checkpatch.pl unhappy - but that's intentional. Is it? I don't know. But not that I mind, so for good measure: Reviewed-by: Max Reitz <mreitz@redhat.com> > Reviewed-by: Eric Blake <eblake@redhat.com>
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