Commit a0c30369 authored by Eric Blake's avatar Eric Blake Committed by Paolo Bonzini
Browse files

nbd: Use BDRV_REQ_FUA for better FUA where supported 



Rather than always flushing ourselves, let the block layer
forward the FUA on to the underlying device - where all
underlying layers also understand FUA, we are now more
efficient; and where any underlying layer doesn't understand
it, now the block layer takes care of the full flush fallback
on our behalf.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Message-Id: <1463006384-7734-2-git-send-email-eblake@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 37146e7e

nbd/server.c

+6 −10
Original line number Diff line number Diff line
@@ -1038,6 +1038,7 @@ static void nbd_trip(void *opaque) 
    struct nbd_reply reply;

    ssize_t ret;

    uint32_t command;

    int flags;



    TRACE("Reading request.");

    if (client->closing) {
@@ -1114,23 +1115,18 @@ static void nbd_trip(void *opaque) 


        TRACE("Writing to device");



        flags = 0;

        if (request.type & NBD_CMD_FLAG_FUA) {

            flags |= BDRV_REQ_FUA;

        }

        ret = blk_pwrite(exp->blk, request.from + exp->dev_offset,

                         req->data, request.len, 0);

                         req->data, request.len, flags);

        if (ret < 0) {

            LOG("writing to file failed");

            reply.error = -ret;

            goto error_reply;

        }



        if (request.type & NBD_CMD_FLAG_FUA) {

            ret = blk_co_flush(exp->blk);

            if (ret < 0) {

                LOG("flush failed");

                reply.error = -ret;

                goto error_reply;

            }

        }



        if (nbd_co_send_reply(req, &reply, 0) < 0) {

            goto out;

        }