kernfs: don't fail listing extended attributes

Userspace doesn't expect a failure to list extended attributes:

  $ ls -lA /sys/
  ls: /sys/: No data available
  ls: /sys/kernel: No data available
  ls: /sys/power: No data available
  ls: /sys/class: No data available
  ls: /sys/devices: No data available
  ls: /sys/dev: No data available
  ls: /sys/hypervisor: No data available
  ls: /sys/fs: No data available
  ls: /sys/bus: No data available
  ls: /sys/firmware: No data available
  ls: /sys/block: No data available
  ls: /sys/module: No data available
  total 0
  drwxr-xr-x   2 root root 0 Jan  1  1970 block
  drwxr-xr-x  52 root root 0 Jan  1  1970 bus
  drwxr-xr-x  88 root root 0 Jan  1  1970 class
  drwxr-xr-x   4 root root 0 Jan  1  1970 dev
  drwxr-xr-x  11 root root 0 Jan  1  1970 devices
  drwxr-xr-x   3 root root 0 Jan  1  1970 firmware
  drwxr-xr-x  10 root root 0 Jan  1  1970 fs
  drwxr-xr-x   2 root root 0 Jul  2 09:43 hypervisor
  drwxr-xr-x  14 root root 0 Jan  1  1970 kernel
  drwxr-xr-x 251 root root 0 Jan  1  1970 module
  drwxr-xr-x   3 root root 0 Jul  2 09:43 power

Fix it by simply reporting success when no extended attributes are
available instead of reporting ENODATA.

Link: https://lore.kernel.org/78b13bcdae82ade95e88f315682966051f461dde.camel@linaro.org
Fixes: d1f4e9026007 ("kernfs: remove iattr_mutex") # mainline only
Reported-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/20250819-ahndung-abgaben-524a535f8101@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 3c293a5a21b1ce0ff0e4675fa4dc4b8a4e5d04d8..457f91c412d4835b1cffd7ad73a160c596730281 100644 (file)
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -142,9 +142,9 @@ ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
        struct kernfs_node *kn = kernfs_dentry_node(dentry);
        struct kernfs_iattrs *attrs;
 
-       attrs = kernfs_iattrs_noalloc(kn);
+       attrs = kernfs_iattrs(kn);
        if (!attrs)
-               return -ENODATA;
+               return -ENOMEM;
 
        return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
 }