lib/notifier-error-inject: fix error when writing -errno to debugfs file

The simple attribute files do not accept a negative value since the commit
488dac0 ("libfs: fix error cast of negative value in
simple_attr_write()").

This restores the previous behaviour by using newly introduced
DEFINE_SIMPLE_ATTRIBUTE_SIGNED instead of DEFINE_SIMPLE_ATTRIBUTE.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 488dac0 ("libfs: fix error cast of negative value in simple_attr_write()")
Signed-off-by: Akinobu Mita <[email protected]>
Reported-by: Zhao Gongyi <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Wei Yongjun <[email protected]>
Cc: Yicong Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: mita

lib/notifier-error-inject.c

@@ -15,7 +15,7 @@ static int debugfs_errno_get(void *data, u64 *val)
 	return 0;
 }
 
-DEFINE_SIMPLE_ATTRIBUTE(fops_errno, debugfs_errno_get, debugfs_errno_set,
+DEFINE_SIMPLE_ATTRIBUTE_SIGNED(fops_errno, debugfs_errno_get, debugfs_errno_set,
 			"%lld\n");
 
 static struct dentry *debugfs_create_errno(const char *name, umode_t mode,