ovl: Ensure upper filesystem supports d_type

[linux.git] / fs / overlayfs / readdir.c

diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index fdaf28f75e12acf1f4dba023c31017c81747744b..18d0a16252209cda0411dd10e1e0371cfed06b57 100644 (file)
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -43,6 +43,7 @@ struct ovl_readdir_data {
        struct ovl_cache_entry *first_maybe_whiteout;
        int count;
        int err;
+       bool d_type_supported;
 };
 
 struct ovl_dir_file {
@@ -577,3 +578,39 @@ void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
        }
        inode_unlock(upper->d_inode);
 }
+
+static int ovl_check_d_type(struct dir_context *ctx, const char *name,
+                         int namelen, loff_t offset, u64 ino,
+                         unsigned int d_type)
+{
+       struct ovl_readdir_data *rdd =
+               container_of(ctx, struct ovl_readdir_data, ctx);
+
+       /* Even if d_type is not supported, DT_DIR is returned for . and .. */
+       if (!strncmp(name, ".", namelen) || !strncmp(name, "..", namelen))
+               return 0;
+
+       if (d_type != DT_UNKNOWN)
+               rdd->d_type_supported = true;
+
+       return 0;
+}
+
+/*
+ * Returns 1 if d_type is supported, 0 not supported/unknown. Negative values
+ * if error is encountered.
+ */
+int ovl_check_d_type_supported(struct path *realpath)
+{
+       int err;
+       struct ovl_readdir_data rdd = {
+               .ctx.actor = ovl_check_d_type,
+               .d_type_supported = false,
+       };
+
+       err = ovl_dir_read(realpath, &rdd);
+       if (err)
+               return err;
+
+       return rdd.d_type_supported;
+}