vfs: merge .d_select_inode() into .d_real()

The two methods essentially do the same: find the real dentry/inode
belonging to an overlay dentry.  The difference is in the usage:

vfs_open() uses ->d_select_inode() and expects the function to perform
copy-up if necessary based on the open flags argument.

file_dentry() uses ->d_real() passing in the overlay dentry as well as the
underlying inode.

vfs_rename() uses ->d_select_inode() but passes zero flags.  ->d_real()
with a zero inode would have worked just as well here.

This patch merges the functionality of ->d_select_inode() into ->d_real()
by adding an 'open_flags' argument to the latter.

[Al Viro] Make the signature of d_real() match that of ->d_real() again.
And constify the inode argument, while we are at it.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 10 insertions, 21 deletions

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 1dbeab6cf96e..e08cd94d7b26 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -325,36 +325,25 @@ static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
 	return true;
 }
 
-struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags)
+int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
 {
-	int err;
+	int err = 0;
 	struct path realpath;
 	enum ovl_path_type type;
 
-	if (d_is_dir(dentry))
-		return d_backing_inode(dentry);
-
 	type = ovl_path_real(dentry, &realpath);
 	if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
 		err = ovl_want_write(dentry);
-		if (err)
-			return ERR_PTR(err);
-
-		if (file_flags & O_TRUNC)
-			err = ovl_copy_up_truncate(dentry);
-		else
-			err = ovl_copy_up(dentry);
-		ovl_drop_write(dentry);
-		if (err)
-			return ERR_PTR(err);
-
-		ovl_path_upper(dentry, &realpath);
+		if (!err) {
+			if (file_flags & O_TRUNC)
+				err = ovl_copy_up_truncate(dentry);
+			else
+				err = ovl_copy_up(dentry);
+			ovl_drop_write(dentry);
+		}
 	}
 
-	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);
+	return err;
 }
 
 static const struct inode_operations ovl_file_inode_operations = {