• Souptick Joarder's avatar
    mm: change return type to vm_fault_t · 1c8f4220
    Souptick Joarder authored
    The plan for these patches is to introduce the typedef, initially just
    as documentation ("These functions should return a VM_FAULT_ status").
    We'll trickle the patches to individual drivers/filesystems in through
    the maintainers, as far as possible.  Then we'll change the typedef to
    an unsigned int and break the compilation of any unconverted
    drivers/filesystems.
    
    vmf_insert_page(), vmf_insert_mixed() and vmf_insert_pfn() are three
    newly added functions.  The various drivers/filesystems where return
    value of fault(), huge_fault(), page_mkwrite() and pfn_mkwrite() get
    converted, will need them.  These functions will return correct
    VM_FAULT_ code based on err value.
    
    We've had bugs before where drivers returned -EFOO.  And we have this
    silly inefficiency where vm_insert_xxx() return an errno which (afaict)
    every driver then converts into a VM_FAULT code.  In many cases drivers
    failed to return correct VM_FAULT code value despite of vm_insert_xxx()
    fails.  We have indentified and clean up all those existing bugs and
    silly inefficiencies in driver/filesystems by adding these three new
    inline wrappers.  As mentioned above, we will trickle those patches to
    individual drivers/filesystems in through maintainers after these three
    wrapper functions are merged.
    
    Eventually we can convert vm_insert_xxx() into vmf_insert_xxx() and
    remove these inline wrappers, but these are a good intermediate step.
    
    Link: http://lkml.kernel.org/r/20180310162351.GA7422@jordon-HP-15-Notebook-PC
    
    Signed-off-by: default avatarSouptick Joarder <jrdr.linux@gmail.com>
    Acked-by: default avatarMichal Hocko <mhocko@suse.com>
    Cc: Matthew Wilcox <willy@infradead.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    1c8f4220