From e8d1b1d0ceb24d95d85f7c891e331770603faf6e Mon Sep 17 00:00:00 2001
From: jh <jh@FreeBSD.org>
Date: Mon, 16 Apr 2012 18:07:42 +0000
Subject: tmpfs: Allow update mounts only for certain options.

Since r230208 update mounts were allowed if the list of mount options
contained the "export" option. This is not correct as tmpfs doesn't
really support updating all options.

Reviewed by:	kevlo, trociny
---
 sys/fs/tmpfs/tmpfs.h        |  3 +++
 sys/fs/tmpfs/tmpfs_vfsops.c | 18 ++++++++++++------
 2 files changed, 15 insertions(+), 6 deletions(-)

(limited to 'sys/fs/tmpfs')

diff --git a/sys/fs/tmpfs/tmpfs.h b/sys/fs/tmpfs/tmpfs.h
index fad97ac..1c6d714 100644
--- a/sys/fs/tmpfs/tmpfs.h
+++ b/sys/fs/tmpfs/tmpfs.h
@@ -387,6 +387,9 @@ struct tmpfs_mount {
 	 * tmpfs_pool.c. */
 	uma_zone_t		tm_dirent_pool;
 	uma_zone_t		tm_node_pool;
+
+	/* Read-only status. */
+	int			tm_ronly;
 };
 #define TMPFS_LOCK(tm) mtx_lock(&(tm)->allnode_lock)
 #define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->allnode_lock)
diff --git a/sys/fs/tmpfs/tmpfs_vfsops.c b/sys/fs/tmpfs/tmpfs_vfsops.c
index 96d7321..a08dafa 100644
--- a/sys/fs/tmpfs/tmpfs_vfsops.c
+++ b/sys/fs/tmpfs/tmpfs_vfsops.c
@@ -82,6 +82,10 @@ static const char *tmpfs_opts[] = {
 	NULL
 };
 
+static const char *tmpfs_updateopts[] = {
+	"from", "export", NULL
+};
+
 /* --------------------------------------------------------------------- */
 
 static int
@@ -150,12 +154,13 @@ tmpfs_mount(struct mount *mp)
 		return (EINVAL);
 
 	if (mp->mnt_flag & MNT_UPDATE) {
-		/*
-		 * Only support update mounts for NFS export.
-		 */
-		if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0))
-			return (0);
-		return (EOPNOTSUPP);
+		/* Only support update mounts for certain options. */
+		if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0)
+			return (EOPNOTSUPP);
+		if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) !=
+		    ((struct tmpfs_mount *)mp->mnt_data)->tm_ronly)
+			return (EOPNOTSUPP);
+		return (0);
 	}
 
 	vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY);
@@ -228,6 +233,7 @@ tmpfs_mount(struct mount *mp)
 	    tmpfs_node_ctor, tmpfs_node_dtor,
 	    tmpfs_node_init, tmpfs_node_fini,
 	    UMA_ALIGN_PTR, 0);
+	tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
 
 	/* Allocate the root node. */
 	error = tmpfs_alloc_node(tmp, VDIR, root_uid,
-- 
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