| Message ID | 1476971860-20860-8-git-send-email-zhang.zhanghailiang@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 10/20/2016 08:57 AM, zhanghailiang wrote: > Without this callback, there will be an error reports in the primary side: > "qemu-system-x86_64: Couldn't determine the cluster size of the target image, > which has no backing file: Operation not supported > Aborting, since this may create an unusable destination image" > > For nbd driver, it doesn't have cluster size, so here we return > a fake value for it. > > Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com> > Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> > --- > block/nbd.c | 12 ++++++++++++ > block/replication.c | 6 ++++++ > 2 files changed, 18 insertions(+) > > diff --git a/block/nbd.c b/block/nbd.c > index 6bc06d6..96d7023 100644 > --- a/block/nbd.c > +++ b/block/nbd.c > @@ -40,6 +40,8 @@ > > #define EN_OPTSTR ":exportname=" > > +#define NBD_FAKE_CLUSTER_SIZE 512 Why 512? NBD allows byte-addressable operations (even if it is more efficient on aligned I/O); and I've been working hard to convert things to the point that NBD does not enforce alignment on other layers. Wouldn't 1 be better? > +static int nbd_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) > +{ > + bdi->cluster_size = NBD_FAKE_CLUSTER_SIZE; I also have patches written (but waiting for NBD write zeroes support to be reviewed first) that add support for the experimental NBD block info, that lets a server advertise actual sizes to the client rather than having to guess. Here's the last time I posted a preview of it: https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg03567.html It would be nice to use that instead of just faking things.
Hi, On 2016/10/20 23:34, Eric Blake wrote: > On 10/20/2016 08:57 AM, zhanghailiang wrote: >> Without this callback, there will be an error reports in the primary side: >> "qemu-system-x86_64: Couldn't determine the cluster size of the target image, >> which has no backing file: Operation not supported >> Aborting, since this may create an unusable destination image" >> >> For nbd driver, it doesn't have cluster size, so here we return >> a fake value for it. >> >> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com> >> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> >> --- >> block/nbd.c | 12 ++++++++++++ >> block/replication.c | 6 ++++++ >> 2 files changed, 18 insertions(+) >> >> diff --git a/block/nbd.c b/block/nbd.c >> index 6bc06d6..96d7023 100644 >> --- a/block/nbd.c >> +++ b/block/nbd.c >> @@ -40,6 +40,8 @@ >> >> #define EN_OPTSTR ":exportname=" >> >> +#define NBD_FAKE_CLUSTER_SIZE 512 > > Why 512? NBD allows byte-addressable operations (even if it is more > efficient on aligned I/O); and I've been working hard to convert things > to the point that NBD does not enforce alignment on other layers. > Wouldn't 1 be better? > Yes, that makes no difference for block replication driver. :) >> +static int nbd_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) >> +{ >> + bdi->cluster_size = NBD_FAKE_CLUSTER_SIZE; > > I also have patches written (but waiting for NBD write zeroes support to > be reviewed first) that add support for the experimental NBD block info, > that lets a server advertise actual sizes to the client rather than > having to guess. Here's the last time I posted a preview of it: > > https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg03567.html > > It would be nice to use that instead of just faking things. > That's great, that's what we really want, here it is just a temporary solution, I'll drop this patch after you nbd patch been merged. Thanks, Hailiang
diff --git a/block/nbd.c b/block/nbd.c index 6bc06d6..96d7023 100644 --- a/block/nbd.c +++ b/block/nbd.c @@ -40,6 +40,8 @@ #define EN_OPTSTR ":exportname=" +#define NBD_FAKE_CLUSTER_SIZE 512 + typedef struct BDRVNBDState { NbdClientSession client; @@ -483,6 +485,13 @@ static void nbd_refresh_filename(BlockDriverState *bs, QDict *options) bs->full_open_options = opts; } +static int nbd_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) +{ + bdi->cluster_size = NBD_FAKE_CLUSTER_SIZE; + + return 0; +} + static BlockDriver bdrv_nbd = { .format_name = "nbd", .protocol_name = "nbd", @@ -499,6 +508,7 @@ static BlockDriver bdrv_nbd = { .bdrv_detach_aio_context = nbd_detach_aio_context, .bdrv_attach_aio_context = nbd_attach_aio_context, .bdrv_refresh_filename = nbd_refresh_filename, + .bdrv_get_info = nbd_get_info, }; static BlockDriver bdrv_nbd_tcp = { @@ -517,6 +527,7 @@ static BlockDriver bdrv_nbd_tcp = { .bdrv_detach_aio_context = nbd_detach_aio_context, .bdrv_attach_aio_context = nbd_attach_aio_context, .bdrv_refresh_filename = nbd_refresh_filename, + .bdrv_get_info = nbd_get_info, }; static BlockDriver bdrv_nbd_unix = { @@ -535,6 +546,7 @@ static BlockDriver bdrv_nbd_unix = { .bdrv_detach_aio_context = nbd_detach_aio_context, .bdrv_attach_aio_context = nbd_attach_aio_context, .bdrv_refresh_filename = nbd_refresh_filename, + .bdrv_get_info = nbd_get_info, }; static void bdrv_nbd_init(void) diff --git a/block/replication.c b/block/replication.c index e66b1ca..14c718e 100644 --- a/block/replication.c +++ b/block/replication.c @@ -707,6 +707,11 @@ static void replication_stop(ReplicationState *rs, bool failover, Error **errp) aio_context_release(aio_context); } +static int replication_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) +{ + return bdrv_get_info(bs->file->bs, bdi); +} + BlockDriver bdrv_replication = { .format_name = "replication", .protocol_name = "replication", @@ -719,6 +724,7 @@ BlockDriver bdrv_replication = { .bdrv_co_readv = replication_co_readv, .bdrv_co_writev = replication_co_writev, + .bdrv_get_info = replication_get_info, .is_filter = true, .bdrv_recurse_is_first_non_filter = replication_recurse_is_first_non_filter,