[PATCH 4.2 085/110] ovl: fix open in stacked overlay

From: Greg Kroah-Hartman
Date: Fri Nov 06 2015 - 14:30:03 EST

4.2-stable review patch. If anyone has any objections, please let me know.


From: Miklos Szeredi <miklos@xxxxxxxxxx>

commit 1c8a47df36d72ace8cf78eb6c228aa0f8027d3c2 upstream.

If two overlayfs filesystems are stacked on top of each other, then we need
recursion in ovl_d_select_inode().

I guess d_backing_inode() is supposed to do that. But currently it doesn't
and that functionality is open coded in vfs_open(). This is now copied
into ovl_d_select_inode() to fix this regression.

Reported-by: Alban Crequy <alban.crequy@xxxxxxxxx>
Signed-off-by: Miklos Szeredi <miklos@xxxxxxxxxx>
Fixes: 4bacc9c9234c ("overlayfs: Make f_path always point to the overlay...")
Cc: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/overlayfs/inode.c | 3 +++
1 file changed, 3 insertions(+)

--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -363,6 +363,9 @@ struct inode *ovl_d_select_inode(struct
ovl_path_upper(dentry, &realpath);

+ if (realpath.dentry->d_flags & DCACHE_OP_SELECT_INODE)
+ return realpath.dentry->d_op->d_select_inode(realpath.dentry, file_flags);
return d_backing_inode(realpath.dentry);

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