[PATCH 5/7] ovl: Set OVL_METACOPY flag during ovl_lookup()

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During lookup, check for presence of OVL_XATTR_METACOPY and if present,
set OVL_METACOPY bit in flags.

Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
 fs/overlayfs/namei.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index c3addd1114f1..9b6f9afa4f75 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -26,6 +26,24 @@ struct ovl_lookup_data {
 	char *redirect;
 };
 
+/* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
+static int ovl_check_metacopy(struct dentry *dentry)
+{
+	int res;
+
+	res = vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
+	if (res < 0) {
+		if (res == -ENODATA || res == -EOPNOTSUPP)
+			return 0;
+		goto out;
+	}
+
+	return 1;
+out:
+	pr_warn_ratelimited("overlayfs: failed to get metacopy (%i)\n", res);
+	return res;
+}
+
 static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
 			      size_t prelen, const char *post)
 {
@@ -591,6 +609,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 	struct dentry *this;
 	unsigned int i;
 	int err;
+	bool metacopy = false;
 	struct ovl_lookup_data d = {
 		.name = dentry->d_name,
 		.is_dir = false,
@@ -631,6 +650,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 					       roe->numlower, &stack, &ctr);
 			if (err)
 				goto out;
+
+			err = ovl_check_metacopy(upperdentry);
+			if (err < 0)
+				goto out;
+			if (err == 1)
+				metacopy = true;
 		}
 
 		if (d.redirect) {
@@ -716,6 +741,15 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
 		OVL_I(inode)->redirect = upperredirect;
 		if (index)
 			ovl_set_flag(OVL_INDEX, inode);
+
+		if (metacopy) {
+			/*
+			 * TODO: What happens we if find metacopy xattr but
+			 * could not find/resolve origin.
+			 */
+			WARN_ON(!ctr);
+			ovl_set_flag(OVL_METACOPY, inode);
+		}
 	}
 
 	revert_creds(old_cred);
-- 
2.13.5

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