Eric Blake 7c6f5ddca6 nbd/client: Work around 3.0 bug for listing meta contexts ... Commit 3d068aff forgot to advertise available qemu: contexts when the client requests a list with 0 queries. Furthermore, 3.0 shipped with a qemu-img hack of x-dirty-bitmap (commit 216ee365) that _silently_ acts as though the entire image is clean if a requested bitmap is not present. Both bugs have been recently fixed, so that a modern qemu server gives full context output right away, and the client refuses a connection if a requested x-dirty-bitmap was not found. Still, it is likely that there will be users that have to work with a mix of old and new qemu versions, depending on which features get backported where, at which point being able to rely on 'qemu-img --list' output to know for sure whether a given NBD export has the desired dirty bitmap is much nicer than blindly connecting and risking that the entire image may appear clean. We can make our --list code smart enough to work around buggy servers by tracking whether we've seen any qemu: replies in the original 0-query list; if not, repeat with a single query on "qemu:" (which may still have no replies, but then we know for sure we didn't trip up on the server bug). Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20190117193658.16413-21-eblake@redhat.com>		2019-01-21 15:49:52 -06:00
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client.c	nbd/client: Work around 3.0 bug for listing meta contexts	2019-01-21 15:49:52 -06:00
common.c	nbd/server: introduce NBD_CMD_CACHE	2018-06-21 09:41:39 -05:00
Makefile.objs	nbd: Split nbd.c	2016-01-15 18:58:02 +01:00
nbd-internal.h	nbd/client: Drop pointless buf variable	2019-01-05 07:53:22 -06:00
server.c	nbd/server: Favor [u]int64_t over off_t	2019-01-21 15:49:51 -06:00
trace-events	nbd/client: Refactor nbd_opt_go() to support NBD_OPT_INFO	2019-01-21 15:49:52 -06:00