In the case of a bind mounted file, the path walking code will assume that the cached dentry that was bind mounted is valid. This is a problem problem for NFSv4 in a way that's similar to LAST_BIND symlinks. Fix this by revalidating the dentry if FS_FOLLOW_DOT is set and __follow_mount returns true. Note that in the non-open codepath, we cannot return an error to the lookup if the revalidation fails. Doing so will leave a bind mount in a state such that we can't unmount it. In that case we'll just have to settle for d_invalidating it (which should mostly turn out to be a d_drop in this case) and returning success. Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> --- fs/namei.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 339789e..0d55b6f 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -851,7 +851,13 @@ static int do_lookup(struct nameidata *nd, struct qstr *name, done: path->mnt = mnt; path->dentry = dentry; - __follow_mount(path); + + /* + * cannot return the error returned by force_reval_path as that can + * make it impossible to unmount a bind mounted dentry if it's stale. + */ + if (__follow_mount(path)) + force_reval_path(path, nd); return 0; need_lookup: @@ -1840,6 +1846,9 @@ do_last: error = -ELOOP; if (flag & O_NOFOLLOW) goto exit_dput; + error = force_reval_path(&path, &nd); + if (error) + goto exit_dput; } error = -ENOENT; -- 1.5.5.6 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
