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| author | Eric Blake <eblake@redhat.com> | 2017-11-06 21:09:12 -0600 |
|---|---|---|
| committer | Eric Blake <eblake@redhat.com> | 2018-01-08 09:12:23 -0600 |
| commit | e2de3256c373fe32c7a7d9ef2f2093c643bb6656 (patch) | |
| tree | 524aa4ff19872df73605600015ab6a597da2864b /nbd/server.c | |
| parent | 418638d3e448e0ed79d55cc43a26f7a65c22007f (diff) | |
| download | qemu-e2de3256c373fe32c7a7d9ef2f2093c643bb6656.tar.gz | |
nbd/server: Optimize final chunk of sparse read
If we are careful to handle 0-length read requests correctly,
we can optimize our sparse read to send the NBD_REPLY_FLAG_DONE
bit on our last OFFSET_DATA or OFFSET_HOLE chunk rather than
needing a separate chunk.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171107030912.23930-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Diffstat (limited to 'nbd/server.c')
| -rw-r--r-- | nbd/server.c | 13 |
1 files changed, 7 insertions, 6 deletions
diff --git a/nbd/server.c b/nbd/server.c index be7310cb41..e443b3cf5c 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1339,12 +1339,14 @@ static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client, offset + progress, size - progress, &pnum, NULL, NULL); + bool final; if (status < 0) { error_setg_errno(errp, -status, "unable to check for holes"); return status; } assert(pnum && pnum <= size - progress); + final = progress + pnum == size; if (status & BDRV_BLOCK_ZERO) { NBDStructuredReadHole chunk; struct iovec iov[] = { @@ -1353,7 +1355,8 @@ static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client, trace_nbd_co_send_structured_read_hole(handle, offset + progress, pnum); - set_be_chunk(&chunk.h, 0, NBD_REPLY_TYPE_OFFSET_HOLE, + set_be_chunk(&chunk.h, final ? NBD_REPLY_FLAG_DONE : 0, + NBD_REPLY_TYPE_OFFSET_HOLE, handle, sizeof(chunk) - sizeof(chunk.h)); stq_be_p(&chunk.offset, offset + progress); stl_be_p(&chunk.length, pnum); @@ -1366,7 +1369,7 @@ static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client, break; } ret = nbd_co_send_structured_read(client, handle, offset + progress, - data + progress, pnum, false, + data + progress, pnum, final, errp); } @@ -1375,9 +1378,6 @@ static int coroutine_fn nbd_co_send_sparse_read(NBDClient *client, } progress += pnum; } - if (!ret) { - ret = nbd_co_send_structured_done(client, handle, errp); - } return ret; } @@ -1542,7 +1542,8 @@ static coroutine_fn void nbd_trip(void *opaque) } } - if (client->structured_reply && !(request.flags & NBD_CMD_FLAG_DF)) { + if (client->structured_reply && !(request.flags & NBD_CMD_FLAG_DF) && + request.len) { ret = nbd_co_send_sparse_read(req->client, request.handle, request.from, req->data, request.len, &local_err); |