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| author | Eric Blake <eblake@redhat.com> | 2017-11-08 15:57:03 -0600 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2017-11-09 10:25:11 -0600 |
| commit | ef8c887ee01a4e4c8c5c28c86ea5b45162c51bcd (patch) | |
| tree | e6eaa1e3a1825c56e6da57211be6d4b61d59a8e3 /nbd/trace-events | |
| parent | b4176cb314995ad225d6c2b531568801feb04f3f (diff) | |
| download | qemu-ef8c887ee01a4e4c8c5c28c86ea5b45162c51bcd.tar.gz | |
nbd/server: Fix structured read of length 0
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>
Diffstat (limited to 'nbd/trace-events')
| -rw-r--r-- | nbd/trace-events | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/nbd/trace-events b/nbd/trace-events index bbc75f6414..92568edce5 100644 --- a/nbd/trace-events +++ b/nbd/trace-events @@ -55,6 +55,7 @@ nbd_receive_request(uint32_t magic, uint16_t flags, uint16_t type, uint64_t from nbd_blk_aio_attached(const char *name, void *ctx) "Export %s: Attaching clients to AIO context %p\n" nbd_blk_aio_detach(const char *name, void *ctx) "Export %s: Detaching clients from AIO context %p\n" nbd_co_send_simple_reply(uint64_t handle, uint32_t error, const char *errname, int len) "Send simple reply: handle = %" PRIu64 ", error = %" PRIu32 " (%s), len = %d" +nbd_co_send_structured_done(uint64_t handle) "Send structured reply done: handle = %" PRIu64 nbd_co_send_structured_read(uint64_t handle, uint64_t offset, void *data, size_t size) "Send structured read data reply: handle = %" PRIu64 ", offset = %" PRIu64 ", data = %p, len = %zu" nbd_co_send_structured_error(uint64_t handle, int err, const char *errname, const char *msg) "Send structured error reply: handle = %" PRIu64 ", error = %d (%s), msg = '%s'" nbd_co_receive_request_decode_type(uint64_t handle, uint16_t type, const char *name) "Decoding type: handle = %" PRIu64 ", type = %" PRIu16 " (%s)" |