Safer nfsd_cross_mnt()
AFAICS, we have a subtle bug there: if we have crossed mountpoint
*and* it got mount --move'd away, we'll be holding only one
reference to fs containing dentry - exp->ex_path.mnt. IOW, we
ought to dput() before exp_put().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index ab93fcf..46e6bd2 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -116,10 +116,15 @@
}
if ((exp->ex_flags & NFSEXP_CROSSMOUNT) || EX_NOHIDE(exp2)) {
/* successfully crossed mount point */
- exp_put(exp);
- *expp = exp2;
+ /*
+ * This is subtle: dentry is *not* under mnt at this point.
+ * The only reason we are safe is that original mnt is pinned
+ * down by exp, so we should dput before putting exp.
+ */
dput(dentry);
*dpp = mounts;
+ exp_put(exp);
+ *expp = exp2;
} else {
exp_put(exp2);
dput(mounts);