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>

1 files changed, 28 insertions, 49 deletions

diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index ab1e3dcbed95..3efa44acf98b 100644
--- 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) {
                 /*