Add mount -ur/uw support to tmpfs.

From Pedro Martelletto

diff --git a/sys/tmpfs/tmpfs_vfsops.c b/sys/tmpfs/tmpfs_vfsops.c
index 4f553fd..55f7312 100644 (file)
--- a/sys/tmpfs/tmpfs_vfsops.c
+++ b/sys/tmpfs/tmpfs_vfsops.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tmpfs_vfsops.c,v 1.17 2019/12/26 13:28:49 bluhm Exp $ */
+/*     $OpenBSD: tmpfs_vfsops.c,v 1.18 2021/10/24 15:33:12 patrick Exp $       */
 /*     $NetBSD: tmpfs_vfsops.c,v 1.52 2011/09/27 01:10:43 christos Exp $       */
 
 /*
@@ -67,6 +67,7 @@ int   tmpfs_vptofh(struct vnode *, struct fid *);
 int    tmpfs_statfs(struct mount *, struct statfs *, struct proc *);
 int    tmpfs_sync(struct mount *, int, int, struct ucred *, struct proc *);
 int    tmpfs_init(struct vfsconf *);
+int    tmpfs_mount_update(struct mount *);
 
 int
 tmpfs_init(struct vfsconf *vfsp)
@@ -80,6 +81,40 @@ tmpfs_init(struct vfsconf *vfsp)
        return 0;
 }
 
+int
+tmpfs_mount_update(struct mount *mp)
+{
+       tmpfs_mount_t *tmp;
+       struct vnode *rootvp;
+       int error;
+
+       if ((mp->mnt_flag & MNT_RDONLY) == 0)
+               return EOPNOTSUPP;
+
+       /* ro->rw transition: nothing to do? */
+       if (mp->mnt_flag & MNT_WANTRDWR)
+               return 0;
+
+       tmp = mp->mnt_data;
+       rootvp = tmp->tm_root->tn_vnode;
+
+       /* Lock root to prevent lookups. */
+       error = vn_lock(rootvp, LK_EXCLUSIVE | LK_RETRY);
+       if (error)
+               return error;
+
+       /* Lock mount point to prevent nodes from being added/removed. */
+       rw_enter_write(&tmp->tm_lock);
+
+       /* Flush files opened for writing; skip rootvp. */
+       error = vflush(mp, rootvp, WRITECLOSE);
+
+       rw_exit_write(&tmp->tm_lock);
+       VOP_UNLOCK(rootvp);
+
+       return error;
+}
+
 int
 tmpfs_mount(struct mount *mp, const char *path, void *data,
     struct nameidata *ndp, struct proc *p)
@@ -112,10 +147,8 @@ tmpfs_mount(struct mount *mp, const char *path, void *data,
        }
 #endif
 
-       if (mp->mnt_flag & MNT_UPDATE) {
-               /* TODO */
-               return EOPNOTSUPP;
-       }
+       if (mp->mnt_flag & MNT_UPDATE)
+               return (tmpfs_mount_update(mp));
 
        /* Prohibit mounts if there is not enough memory. */
        if (tmpfs_mem_info(1) < TMPFS_PAGES_RESERVED)