ovl: check whiteout while reading directory

Don't make a separate pass for checking whiteouts, since we can do it while
reading the upper directory.

This will make it easier to handle multiple layers.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index ab1e3dc..3efa44a 100644 (file)
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -40,6 +40,7 @@ struct ovl_readdir_data {
        struct rb_root root;
        struct list_head *list;
        struct list_head middle;
+       struct dentry *dir;
        int count;
        int err;
 };
@@ -126,6 +127,32 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
        if (p == NULL)
                return -ENOMEM;
 
+       if (d_type == DT_CHR) {
+               struct dentry *dentry;
+               const struct cred *old_cred;
+               struct cred *override_cred;
+
+               override_cred = prepare_creds();
+               if (!override_cred) {
+                       kfree(p);
+                       return -ENOMEM;
+               }
+
+               /*
+                * CAP_DAC_OVERRIDE for lookup
+                */
+               cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
+               old_cred = override_creds(override_cred);
+
+               dentry = lookup_one_len(name, rdd->dir, len);
+               if (!IS_ERR(dentry)) {
+                       p->is_whiteout = ovl_is_whiteout(dentry);
+                       dput(dentry);
+               }
+               revert_creds(old_cred);
+               put_cred(override_cred);
+       }
+
        list_add_tail(&p->l_node, rdd->list);
        rb_link_node(&p->node, parent, newp);
        rb_insert_color(&p->node, &rdd->root);
@@ -231,49 +258,6 @@ static void ovl_dir_reset(struct file *file)
                od->is_real = false;
 }
 
-static int ovl_dir_mark_whiteouts(struct dentry *dir,
-                                 struct ovl_readdir_data *rdd)
-{
-       struct ovl_cache_entry *p;
-       struct dentry *dentry;
-       const struct cred *old_cred;
-       struct cred *override_cred;
-
-       override_cred = prepare_creds();
-       if (!override_cred) {
-               ovl_cache_free(rdd->list);
-               return -ENOMEM;
-       }
-
-       /*
-        * CAP_DAC_OVERRIDE for lookup
-        */
-       cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
-       old_cred = override_creds(override_cred);
-
-       mutex_lock(&dir->d_inode->i_mutex);
-       list_for_each_entry(p, rdd->list, l_node) {
-               if (p->is_cursor)
-                       continue;
-
-               if (p->type != DT_CHR)
-                       continue;
-
-               dentry = lookup_one_len(p->name, dir, p->len);
-               if (IS_ERR(dentry))
-                       continue;
-
-               p->is_whiteout = ovl_is_whiteout(dentry);
-               dput(dentry);
-       }
-       mutex_unlock(&dir->d_inode->i_mutex);
-
-       revert_creds(old_cred);
-       put_cred(override_cred);
-
-       return 0;
-}
-
 static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list)
 {
        int err;
@@ -290,15 +274,10 @@ static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list)
        ovl_path_upper(dentry, &upperpath);
 
        if (upperpath.dentry) {
+               rdd.dir = upperpath.dentry;
                err = ovl_dir_read(&upperpath, &rdd);
                if (err)
                        goto out;
-
-               if (lowerpath.dentry) {
-                       err = ovl_dir_mark_whiteouts(upperpath.dentry, &rdd);
-                       if (err)
-                               goto out;
-               }
        }
        if (lowerpath.dentry) {
                /*