On Thu, 10 Mar 2022 10:13:33 +0100 Christian Schoenebeck <qemu_...@crudebyte.com> wrote:
> On Mittwoch, 9. März 2022 18:57:39 CET Christian Schoenebeck wrote: > > Current implementation of 'Twalk' request handling always sends an 'Rerror' > > response if any error occured. The 9p2000 protocol spec sais though: > > > > " > > If the first element cannot be walked for any reason, Rerror is returned. > > Otherwise, the walk will return an Rwalk message containing nwqid qids > > corresponding, in order, to the files that are visited by the nwqid > > successful elementwise walks; nwqid is therefore either nwname or the > > index of the first elementwise walk that failed. > > " > > > > http://ericvh.github.io/9p-rfc/rfc9p2000.html#anchor33 > > > > For that reason we are no longer leaving from an error path in function > > v9fs_walk(), unless really no path component could be walked successfully or > > if the request has been interrupted. > > > > Local variable 'nvalid' counts and reflects the number of path components > > successfully processed by background I/O thread, whereas local variable > > 'name_idx' subsequently counts and reflects the number of path components > > eventually accepted successfully by 9p server controller portion. > > > > New local variable 'any_err' is an aggregate variable reflecting whether any > > error occurred at all, while already existing variable 'err' only reflects > > the last error. > > > > Despite QIDs being delivered to client in a more relaxed way now, it is > > important to note though that fid still must remain uneffacted if any error > > Typo: should be "unaffected". > > > occurred. > > > > Signed-off-by: Christian Schoenebeck <qemu_...@crudebyte.com> > > --- > > hw/9pfs/9p.c | 29 +++++++++++++++++++++-------- > > 1 file changed, 21 insertions(+), 8 deletions(-) > > > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > > index 6cdc566866..8ccd180608 100644 > > --- a/hw/9pfs/9p.c > > +++ b/hw/9pfs/9p.c > > @@ -1766,7 +1766,7 @@ static void coroutine_fn v9fs_walk(void *opaque) > > { > > int name_idx, nvalid; > > g_autofree V9fsQID *qids = NULL; > > - int i, err = 0; > > + int i, err = 0, any_err = 0; > > V9fsPath dpath, path; > > P9ARRAY_REF(V9fsPath) pathes = NULL; > > uint16_t nwnames; > > @@ -1832,6 +1832,7 @@ static void coroutine_fn v9fs_walk(void *opaque) > > * driver code altogether inside the following block. > > */ > > v9fs_co_run_in_worker({ > > + nvalid = 0; > > if (v9fs_request_cancelled(pdu)) { > > err = -EINTR; > > break; > > @@ -1842,7 +1843,7 @@ static void coroutine_fn v9fs_walk(void *opaque) > > break; > > } > > stbuf = fidst; > > - for (nvalid = 0; nvalid < nwnames; nvalid++) { > > + for (; nvalid < nwnames; nvalid++) { > > if (v9fs_request_cancelled(pdu)) { > > err = -EINTR; > > break; > > @@ -1874,12 +1875,13 @@ static void coroutine_fn v9fs_walk(void *opaque) > > /* > > * Handle all the rest of this Twalk request on main thread ... > > */ > > - if (err < 0) { > > + if ((err < 0 && !nvalid) || err == -EINTR) { > > goto out; > > } > > > > + any_err |= err; > > err = stat_to_qid(pdu, &fidst, &qid); > > - if (err < 0) { > > + if (err < 0 && !nvalid) { > > goto out; > > } > > stbuf = fidst; > > @@ -1888,20 +1890,30 @@ static void coroutine_fn v9fs_walk(void *opaque) > > v9fs_path_copy(&dpath, &fidp->path); > > v9fs_path_copy(&path, &fidp->path); > > > > - for (name_idx = 0; name_idx < nwnames; name_idx++) { > > + for (name_idx = 0; name_idx < nvalid; name_idx++) { > > if (!same_stat_id(&pdu->s->root_st, &stbuf) || > > strcmp("..", wnames[name_idx].data)) > > { > > stbuf = stbufs[name_idx]; > > err = stat_to_qid(pdu, &stbuf, &qid); > > if (err < 0) { > > - goto out; > > + break; > > } > > v9fs_path_copy(&path, &pathes[name_idx]); > > v9fs_path_copy(&dpath, &path); > > } > > memcpy(&qids[name_idx], &qid, sizeof(qid)); > > } > > + any_err |= err; > > + if (any_err) { > > > Not sure if there is ever the case err > 0, but as we are already comparing > for "if (err < 0)" everywhere, we should probably also do the same comparison > for the aggregate error variable here, right? > It seems that you could drop any_err and just check name_idx != nwnames ? > if (any_err < 0) { > ... > > > + if (!name_idx) { > > + /* don't send any QIDs, send Rlerror instead */ > > + goto out; > > + } else { > > + /* send QIDs (not Rlerror), but fid MUST remain unaffected */ > > + goto send_qids; > > + } > > + } > > if (fid == newfid) { > > if (fidp->fid_type != P9_FID_NONE) { > > err = -EINVAL; > > @@ -1919,8 +1931,9 @@ static void coroutine_fn v9fs_walk(void *opaque) > > newfidp->uid = fidp->uid; > > v9fs_path_copy(&newfidp->path, &path); > > } > > - err = v9fs_walk_marshal(pdu, nwnames, qids); > > - trace_v9fs_walk_return(pdu->tag, pdu->id, nwnames, qids); > > +send_qids: > > + err = v9fs_walk_marshal(pdu, name_idx, qids); > > + trace_v9fs_walk_return(pdu->tag, pdu->id, name_idx, qids); > > out: > > put_fid(pdu, fidp); > > if (newfidp) { > >
