mm: remove write/force parameters from __get_user_pages_locked()

This removes the redundant 'write' and 'force' parameters from
__get_user_pages_locked() to make the use of FOLL_FORCE explicit in
callers as use of this flag can result in surprising behaviour (and
hence bugs) within the mm subsystem.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/gup.c b/mm/gup.c
index 22cc22e7432f605cd463f945f776c2b78a6fa7d1..720eb93852043107e9562e9019c9f27e3efb8465 100644 (file)
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -739,7 +739,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
                                                struct mm_struct *mm,
                                                unsigned long start,
                                                unsigned long nr_pages,
-                                               int write, int force,
                                                struct page **pages,
                                                struct vm_area_struct **vmas,
                                                int *locked, bool notify_drop,
@@ -757,10 +756,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
 
        if (pages)
                flags |= FOLL_GET;
-       if (write)
-               flags |= FOLL_WRITE;
-       if (force)
-               flags |= FOLL_FORCE;
 
        pages_done = 0;
        lock_dropped = false;
@@ -856,9 +851,15 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
                           int write, int force, struct page **pages,
                           int *locked)
 {
+       unsigned int flags = FOLL_TOUCH;
+
+       if (write)
+               flags |= FOLL_WRITE;
+       if (force)
+               flags |= FOLL_FORCE;
+
        return __get_user_pages_locked(current, current->mm, start, nr_pages,
-                                      write, force, pages, NULL, locked, true,
-                                      FOLL_TOUCH);
+                                      pages, NULL, locked, true, flags);
 }
 EXPORT_SYMBOL(get_user_pages_locked);
 
@@ -879,9 +880,15 @@ __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct m
 {
        long ret;
        int locked = 1;
+
+       if (write)
+               gup_flags |= FOLL_WRITE;
+       if (force)
+               gup_flags |= FOLL_FORCE;
+
        down_read(&mm->mmap_sem);
-       ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
-                                     pages, NULL, &locked, false, gup_flags);
+       ret = __get_user_pages_locked(tsk, mm, start, nr_pages, pages, NULL,
+                                     &locked, false, gup_flags);
        if (locked)
                up_read(&mm->mmap_sem);
        return ret;
@@ -973,9 +980,15 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
                int write, int force, struct page **pages,
                struct vm_area_struct **vmas)
 {
-       return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
-                                      pages, vmas, NULL, false,
-                                      FOLL_TOUCH | FOLL_REMOTE);
+       unsigned int flags = FOLL_TOUCH | FOLL_REMOTE;
+
+       if (write)
+               flags |= FOLL_WRITE;
+       if (force)
+               flags |= FOLL_FORCE;
+
+       return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
+                                      NULL, false, flags);
 }
 EXPORT_SYMBOL(get_user_pages_remote);
 
@@ -989,9 +1002,15 @@ long get_user_pages(unsigned long start, unsigned long nr_pages,
                int write, int force, struct page **pages,
                struct vm_area_struct **vmas)
 {
+       unsigned int flags = FOLL_TOUCH;
+
+       if (write)
+               flags |= FOLL_WRITE;
+       if (force)
+               flags |= FOLL_FORCE;
+
        return __get_user_pages_locked(current, current->mm, start, nr_pages,
-                                      write, force, pages, vmas, NULL, false,
-                                      FOLL_TOUCH);
+                                      pages, vmas, NULL, false, flags);
 }
 EXPORT_SYMBOL(get_user_pages);