[PATCH] kernfs: don't fail listing extended attributes

[Christian Brauner <brauner@xxxxxxxxxx>]

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.

Fixes: d1f4e9026007 ("kernfs: remove iattr_mutex") # mainline only
Reported-by: André Draszik <andre.draszik@xxxxxxxxxx>
Link: https://lore.kernel.org/78b13bcdae82ade95e88f315682966051f461dde.camel@xxxxxxxxxx
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
---
 fs/kernfs/inode.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 3c293a5a21b1..457f91c412d4 100644
--- 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);
 }
-- 
2.47.2