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The NBD spec was recently clarified to state that a read of length 0 should not be attempted by a compliant client; but that a server must still handle it correctly in an unspecified manner (that is, either a successful no-op or an error reply, but not a crash) [1]. However, it also implies that NBD_REPLY_TYPE_OFFSET_DATA must have a non-zero payload length, but our existing code was replying with a chunk that a picky client could reject as invalid because it was missing a payload (our own client implementation was recently patched to be that picky, after first fixing it to not send 0-length requests). We are already doing successful no-ops for 0-length writes and for non-structured reads; so for consistency, we want structured reply reads to also be a no-op. The easiest way to do this is to return a NBD_REPLY_TYPE_NONE chunk; this is best done via a new helper function (especially since future patches for other structured replies may benefit from using the same helper). [1] https://github.com/NetworkBlockDevice/nbd/commit/ee926037 Signed-off-by: Eric Blake <eblake@redhat.com> Message-Id: <20171108215703.9295-8-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> |
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| .. | ||
| client.c | ||
| common.c | ||
| Makefile.objs | ||
| nbd-internal.h | ||
| server.c | ||
| trace-events | ||