During lookup, check for presence of OVL_XATTR_METACOPY and if not present,
set OVL_UPPERDATA bit in flags. This is only done for upper inode with a
corresponding lower dentry and file needs to be a regular file. Basically
any file which is eligible for metadata only copy up.
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
fs/overlayfs/namei.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index aec543d..52cd6ca 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)
{
@@ -594,6 +612,7 @@ 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,
@@ -634,6 +653,20 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
roe->numlower, &stack, &ctr);
if (err)
goto out_put_upper;
+
+ err = ovl_check_metacopy(upperdentry);
+ metacopy = err;
+ if (err < 0)
+ goto out_put_upper;
+ if (metacopy && !ctr) {
+ /*
+ * Found an upper with metacopy set but at the
+ * same time there is no lower dentry. Something
+ * is not right.
+ */
+ err = -ESTALE;
+ goto out_put_upper;
+ }
}
if (d.redirect) {
@@ -719,6 +752,9 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
OVL_I(inode)->redirect = upperredirect;
if (index)
ovl_set_flag(OVL_INDEX, inode);
+
+ if (upperdentry && ctr && S_ISREG(inode->i_mode) && !metacopy)
+ ovl_set_flag(OVL_UPPERDATA, inode);
}
revert_creds(old_cred);
--
2.5.5
--
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