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| author | Eric Blake | 2019-04-03 05:05:22 +0200 |
|---|---|---|
| committer | Eric Blake | 2019-04-08 20:49:25 +0200 |
| commit | 099fbcd65c2064a4ba8251e749bf600055027759 (patch) | |
| tree | c8c01817bf1fd4b69c55c4734b574282085bf5b4 /nbd/server.c | |
| parent | nbd/server: Trace client noncompliance on unaligned requests (diff) | |
| download | qemu-099fbcd65c2064a4ba8251e749bf600055027759.tar.gz qemu-099fbcd65c2064a4ba8251e749bf600055027759.tar.xz qemu-099fbcd65c2064a4ba8251e749bf600055027759.zip | |
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 <eblake@redhat.com>
Message-Id: <20190403030526.12258-4-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, 8 insertions, 5 deletions
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, |