GitLab

From: BlaisorBlade <blaisorblade_spam@yahoo.it>, and me

- remove unused `file *' arg from do_write_mem()

- Add checking for copy_from_user() failures in do_write_mem()

- Return correct value from kmem writes() when a fault is encountered.  A
  write()-style syscall's return values are:

   0 when nothing was written and there was no error (someone tried to
   write zero bytes)

   >0: the number of bytes copied, whether or not there was an error.
   Userspace detects errors by noting that the write() return value is less
   than was requested.

   <0: there was an error and no bytes were copied