[Qemu-devel] [PATCH] qemu-nbd: return EROFS for discard on a read-only export

[Paolo Bonzini]

This is consistent with the handling of writes.

Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
 nbd.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/nbd.c b/nbd.c
index cb1b9bb..eea8c51 100644
--- a/nbd.c
+++ b/nbd.c
@@ -1325,6 +1325,12 @@ static void nbd_trip(void *opaque)
         break;
     case NBD_CMD_TRIM:
         TRACE("Request type is TRIM");
+        if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
+            TRACE("Server is read-only, return error");
+            reply.error = EROFS;
+            goto error_reply;
+        }
+
         ret = blk_co_discard(exp->blk, (request.from + exp->dev_offset)
                                        / BDRV_SECTOR_SIZE,
                              request.len / BDRV_SECTOR_SIZE);
-- 
2.3.5