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authorEric Blake <eblake@redhat.com>2019-04-02 22:05:22 -0500
committerEric Blake <eblake@redhat.com>2019-04-08 13:49:25 -0500
commit099fbcd65c2064a4ba8251e749bf600055027759 (patch)
treec8c01817bf1fd4b69c55c4734b574282085bf5b4 /nbd
parent6e280648d21d8c0aa8a101b62d0732cd1e608743 (diff)
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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')
-rw-r--r--nbd/server.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/nbd/server.c b/nbd/server.c
index 1c4c547..e21bd50 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,