From 099fbcd65c2064a4ba8251e749bf600055027759 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Tue, 2 Apr 2019 22:05:22 -0500 Subject: nbd/server: Don't fail NBD_OPT_INFO for byte-aligned sources In commit 0c1d50bd, I added a couple of TODO comments about whether we consult bl.request_alignment when responding to NBD_OPT_INFO. At the time, qemu as server was hard-coding an advertised alignment of 512 to clients that promised to obey constraints, and there was no function for getting at a device's preferred alignment. But in hindsight, advertising 512 when the block device prefers 1 caused other compliance problems, and commit b0245d64 changed one of the two TODO comments to advertise a more accurate alignment. Time to fix the other TODO. Doesn't really impact qemu as client (our normal client doesn't use NBD_OPT_INFO, and qemu-nbd --list promises to obey block sizes), but it might prove useful to other clients. Fixes: b0245d64 Signed-off-by: Eric Blake Message-Id: <20190403030526.12258-4-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy --- nbd/server.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'nbd') diff --git a/nbd/server.c b/nbd/server.c index 1c4c5474ad..e21bd501dc 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -643,11 +643,14 @@ static int nbd_negotiate_handle_info(NBDClient *client, uint16_t myflags, return rc; } - /* If the client is just asking for NBD_OPT_INFO, but forgot to - * request block sizes, return an error. - * TODO: consult blk_bs(blk)->request_align, and only error if it - * is not 1? */ - if (client->opt == NBD_OPT_INFO && !blocksize) { + /* + * If the client is just asking for NBD_OPT_INFO, but forgot to + * request block sizes in a situation that would impact + * performance, then return an error. But for NBD_OPT_GO, we + * tolerate all clients, regardless of alignments. + */ + if (client->opt == NBD_OPT_INFO && !blocksize && + blk_get_request_alignment(exp->blk) > 1) { return nbd_negotiate_send_rep_err(client, NBD_REP_ERR_BLOCK_SIZE_REQD, errp, -- cgit v1.2.3