ecryptfs: extend ro check to private mount
So far ecryptfs only verified that the superblock wasn't read-only but
didn't check whether the mount was. This made sense when we did not use
a private mount because the read-only state could change at any point.
Now that we have a private mount and mount properties can't change
behind our back extend the read-only check to include the vfsmount.
The __mnt_is_readonly() helper will check both the mount and the
superblock. Note that before we checked root->d_sb and now we check
mnt->mnt_sb but since we have a matching <vfsmount, dentry> pair here
this is only syntactical change, not a semantic one.
Overlayfs and cachefiles have been changed to check this as well.
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Tyler Hicks <code@tyhicks.com>
Cc: ecryptfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 3ba2c0f..4e5aeec 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -571,7 +571,7 @@
* 1) The lower mount is ro
* 2) The ecryptfs_encrypted_view mount option is specified
*/
- if (sb_rdonly(path.dentry->d_sb) || mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
+ if (__mnt_is_readonly(mnt) || mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
s->s_flags |= SB_RDONLY;
s->s_maxbytes = path.dentry->d_sb->s_maxbytes;
