nfsd4: don't try to encode conflicting owner if low on space
I ran into this corner case in testing: in theory clients can provide
state owners up to 1024 bytes long. In the sessions case there might be
a risk of this pushing us over the DRC slot size.
The conflicting owner isn't really that important, so let's humor a
client that provides a small maxresponsize_cached by allowing ourselves
to return without the conflicting owner instead of outright failing the
operation.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 5d8f915..20aad5a 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1432,7 +1432,8 @@
#define op_encode_change_info_maxsz (5)
#define nfs4_fattr_bitmap_maxsz (4)
-#define op_encode_lockowner_maxsz (1 + XDR_QUADLEN(IDMAP_NAMESZ))
+/* We'll fall back on returning no lockowner if run out of space: */
+#define op_encode_lockowner_maxsz (0)
#define op_encode_lock_denied_maxsz (8 + op_encode_lockowner_maxsz)
#define nfs4_owner_maxsz (1 + XDR_QUADLEN(IDMAP_NAMESZ))
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index a90a1e8..2f0ea20 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2878,9 +2878,20 @@
struct xdr_netobj *conf = &ld->ld_owner;
__be32 *p;
+again:
p = xdr_reserve_space(xdr, 32 + XDR_LEN(conf->len));
- if (!p)
+ if (!p) {
+ /*
+ * Don't fail to return the result just because we can't
+ * return the conflicting open:
+ */
+ if (conf->len) {
+ conf->len = 0;
+ conf->data = NULL;
+ goto again;
+ }
return nfserr_resource;
+ }
WRITE64(ld->ld_start);
WRITE64(ld->ld_length);
WRITE32(ld->ld_type);
@@ -2888,7 +2899,6 @@
WRITEMEM(&ld->ld_clientid, 8);
WRITE32(conf->len);
WRITEMEM(conf->data, conf->len);
- kfree(conf->data);
} else { /* non - nfsv4 lock in conflict, no clientid nor owner */
WRITE64((u64)0); /* clientid */
WRITE32(0); /* length of owner name */
@@ -2905,7 +2915,7 @@
nfserr = nfsd4_encode_stateid(xdr, &lock->lk_resp_stateid);
else if (nfserr == nfserr_denied)
nfserr = nfsd4_encode_lock_denied(xdr, &lock->lk_denied);
-
+ kfree(lock->lk_denied.ld_owner.data);
return nfserr;
}