[PATCH 2/3] vfs: force reval on dentry of bind mounted files on FS_REVAL_DOT filesystems

[Jeff Layton]

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 LOOKUP_OPEN is set and
__follow_mount returns true.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 fs/namei.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 2c10519..738b257 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -838,6 +838,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
 {
 	struct vfsmount *mnt = nd->path.mnt;
 	struct dentry *dentry = __d_lookup(nd->path.dentry, name);
+	int error = 0;
 
 	if (!dentry)
 		goto need_lookup;
@@ -846,8 +847,9 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
 done:
 	path->mnt = mnt;
 	path->dentry = dentry;
-	__follow_mount(path);
-	return 0;
+	if (__follow_mount(path))
+		error = force_reval_path(path, nd);
+	return error;
 
 need_lookup:
 	dentry = real_lookup(nd->path.dentry, name, nd);
@@ -1835,6 +1837,9 @@ do_last:
 		error = -ELOOP;
 		if (flag & O_NOFOLLOW)
 			goto exit_dput;
+		error = force_reval_path(&path, &nd);
+		if (error)
+			goto exit;
 	}
 
 	error = -ENOENT;
-- 
1.5.5.6

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