This patch removes the write and force parameters from get_user_pages_unlocked()
and replaces them with a gup_flags parameter 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 <lstoa...@gmail.com>
---
 arch/mips/mm/gup.c                 |  2 +-
 arch/s390/mm/gup.c                 |  3 ++-
 arch/sh/mm/gup.c                   |  3 ++-
 arch/sparc/mm/gup.c                |  3 ++-
 arch/x86/mm/gup.c                  |  2 +-
 drivers/media/pci/ivtv/ivtv-udma.c |  4 ++--
 drivers/media/pci/ivtv/ivtv-yuv.c  |  5 +++--
 drivers/scsi/st.c                  |  5 ++---
 drivers/video/fbdev/pvr2fb.c       |  4 ++--
 include/linux/mm.h                 |  2 +-
 mm/gup.c                           | 14 ++++----------
 mm/nommu.c                         | 11 ++---------
 mm/util.c                          |  3 ++-
 net/ceph/pagevec.c                 |  2 +-
 14 files changed, 27 insertions(+), 36 deletions(-)

diff --git a/arch/mips/mm/gup.c b/arch/mips/mm/gup.c
index 42d124f..d8c3c15 100644
--- a/arch/mips/mm/gup.c
+++ b/arch/mips/mm/gup.c
@@ -287,7 +287,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, 
int write,
        pages += nr;
 
        ret = get_user_pages_unlocked(start, (end - start) >> PAGE_SHIFT,
-                                     write, 0, pages);
+                                     pages, write ? FOLL_WRITE : 0);
 
        /* Have to be a bit careful with return values */
        if (nr > 0) {
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index adb0c34..18d4107 100644
--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -266,7 +266,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, 
int write,
        /* Try to get the remaining pages with get_user_pages */
        start += nr << PAGE_SHIFT;
        pages += nr;
-       ret = get_user_pages_unlocked(start, nr_pages - nr, write, 0, pages);
+       ret = get_user_pages_unlocked(start, nr_pages - nr, pages,
+                                     write ? FOLL_WRITE : 0);
        /* Have to be a bit careful with return values */
        if (nr > 0)
                ret = (ret < 0) ? nr : ret + nr;
diff --git a/arch/sh/mm/gup.c b/arch/sh/mm/gup.c
index 40fa6c8..063c298 100644
--- a/arch/sh/mm/gup.c
+++ b/arch/sh/mm/gup.c
@@ -258,7 +258,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, 
int write,
                pages += nr;
 
                ret = get_user_pages_unlocked(start,
-                       (end - start) >> PAGE_SHIFT, write, 0, pages);
+                       (end - start) >> PAGE_SHIFT, pages,
+                       write ? FOLL_WRITE : 0);
 
                /* Have to be a bit careful with return values */
                if (nr > 0) {
diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index 4e06750..cd0e32b 100644
--- a/arch/sparc/mm/gup.c
+++ b/arch/sparc/mm/gup.c
@@ -238,7 +238,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, 
int write,
                pages += nr;
 
                ret = get_user_pages_unlocked(start,
-                       (end - start) >> PAGE_SHIFT, write, 0, pages);
+                       (end - start) >> PAGE_SHIFT, pages,
+                       write ? FOLL_WRITE : 0);
 
                /* Have to be a bit careful with return values */
                if (nr > 0) {
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index b8b6a60..0d4fb3e 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -435,7 +435,7 @@ int get_user_pages_fast(unsigned long start, int nr_pages, 
int write,
 
                ret = get_user_pages_unlocked(start,
                                              (end - start) >> PAGE_SHIFT,
-                                             write, 0, pages);
+                                             pages, write ? FOLL_WRITE : 0);
 
                /* Have to be a bit careful with return values */
                if (nr > 0) {
diff --git a/drivers/media/pci/ivtv/ivtv-udma.c 
b/drivers/media/pci/ivtv/ivtv-udma.c
index 4769469..2c9232e 100644
--- a/drivers/media/pci/ivtv/ivtv-udma.c
+++ b/drivers/media/pci/ivtv/ivtv-udma.c
@@ -124,8 +124,8 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long 
ivtv_dest_addr,
        }
 
        /* Get user pages for DMA Xfer */
-       err = get_user_pages_unlocked(user_dma.uaddr, user_dma.page_count, 0,
-                       1, dma->map);
+       err = get_user_pages_unlocked(user_dma.uaddr, user_dma.page_count,
+                       dma->map, FOLL_FORCE);
 
        if (user_dma.page_count != err) {
                IVTV_DEBUG_WARN("failed to map user pages, returned %d instead 
of %d\n",
diff --git a/drivers/media/pci/ivtv/ivtv-yuv.c 
b/drivers/media/pci/ivtv/ivtv-yuv.c
index b094054..f7299d3 100644
--- a/drivers/media/pci/ivtv/ivtv-yuv.c
+++ b/drivers/media/pci/ivtv/ivtv-yuv.c
@@ -76,11 +76,12 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct 
ivtv_user_dma *dma,
 
        /* Get user pages for DMA Xfer */
        y_pages = get_user_pages_unlocked(y_dma.uaddr,
-                       y_dma.page_count, 0, 1, &dma->map[0]);
+                       y_dma.page_count, &dma->map[0], FOLL_FORCE);
        uv_pages = 0; /* silence gcc. value is set and consumed only if: */
        if (y_pages == y_dma.page_count) {
                uv_pages = get_user_pages_unlocked(uv_dma.uaddr,
-                               uv_dma.page_count, 0, 1, &dma->map[y_pages]);
+                               uv_dma.page_count, &dma->map[y_pages],
+                               FOLL_FORCE);
        }
 
        if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) {
diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index 7af5226..618422e 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -4922,9 +4922,8 @@ static int sgl_map_user_pages(struct st_buffer *STbp,
        res = get_user_pages_unlocked(
                uaddr,
                nr_pages,
-               rw == READ,
-               0, /* don't force */
-               pages);
+               pages,
+               rw == READ ? FOLL_WRITE : 0); /* don't force */
 
        /* Errors and no page mapped should return here */
        if (res < nr_pages)
diff --git a/drivers/video/fbdev/pvr2fb.c b/drivers/video/fbdev/pvr2fb.c
index 3b1ca44..a2564ab 100644
--- a/drivers/video/fbdev/pvr2fb.c
+++ b/drivers/video/fbdev/pvr2fb.c
@@ -686,8 +686,8 @@ static ssize_t pvr2fb_write(struct fb_info *info, const 
char *buf,
        if (!pages)
                return -ENOMEM;
 
-       ret = get_user_pages_unlocked((unsigned long)buf, nr_pages, WRITE,
-                       0, pages);
+       ret = get_user_pages_unlocked((unsigned long)buf, nr_pages, pages,
+                       FOLL_WRITE);
 
        if (ret < nr_pages) {
                nr_pages = ret;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2db98b6..6adc4bc 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1287,7 +1287,7 @@ long __get_user_pages_unlocked(struct task_struct *tsk, 
struct mm_struct *mm,
                               unsigned long start, unsigned long nr_pages,
                               struct page **pages, unsigned int gup_flags);
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-                   int write, int force, struct page **pages);
+                   struct page **pages, unsigned int gup_flags);
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
                        struct page **pages);
 
diff --git a/mm/gup.c b/mm/gup.c
index 3d620dd..cfcb014 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -897,17 +897,10 @@ EXPORT_SYMBOL(__get_user_pages_unlocked);
  * "force" parameter).
  */
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-                            int write, int force, struct page **pages)
+                            struct page **pages, unsigned int gup_flags)
 {
-       unsigned int flags = FOLL_TOUCH;
-
-       if (write)
-               flags |= FOLL_WRITE;
-       if (force)
-               flags |= FOLL_FORCE;
-
        return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-                                        pages, flags);
+                                        pages, gup_flags | FOLL_TOUCH);
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
@@ -1525,7 +1518,8 @@ int get_user_pages_fast(unsigned long start, int 
nr_pages, int write,
                start += nr << PAGE_SHIFT;
                pages += nr;
 
-               ret = get_user_pages_unlocked(start, nr_pages - nr, write, 0, 
pages);
+               ret = get_user_pages_unlocked(start, nr_pages - nr, pages,
+                               write ? FOLL_WRITE : 0);
 
                /* Have to be a bit careful with return values */
                if (nr > 0) {
diff --git a/mm/nommu.c b/mm/nommu.c
index 925dcc1..7e27add 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -197,17 +197,10 @@ long __get_user_pages_unlocked(struct task_struct *tsk, 
struct mm_struct *mm,
 EXPORT_SYMBOL(__get_user_pages_unlocked);
 
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
-                            int write, int force, struct page **pages)
+                            struct page **pages, unsigned int gup_flags)
 {
-       unsigned int flags = 0;
-
-       if (write)
-               flags |= FOLL_WRITE;
-       if (force)
-               flags |= FOLL_FORCE;
-
        return __get_user_pages_unlocked(current, current->mm, start, nr_pages,
-                                        pages, flags);
+                                        pages, gup_flags);
 }
 EXPORT_SYMBOL(get_user_pages_unlocked);
 
diff --git a/mm/util.c b/mm/util.c
index 662cddf..4c685bd 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -283,7 +283,8 @@ EXPORT_SYMBOL_GPL(__get_user_pages_fast);
 int __weak get_user_pages_fast(unsigned long start,
                                int nr_pages, int write, struct page **pages)
 {
-       return get_user_pages_unlocked(start, nr_pages, write, 0, pages);
+       return get_user_pages_unlocked(start, nr_pages, pages,
+                                      write ? FOLL_WRITE : 0);
 }
 EXPORT_SYMBOL_GPL(get_user_pages_fast);
 
diff --git a/net/ceph/pagevec.c b/net/ceph/pagevec.c
index 00d2601..1a7c9a7 100644
--- a/net/ceph/pagevec.c
+++ b/net/ceph/pagevec.c
@@ -26,7 +26,7 @@ struct page **ceph_get_direct_page_vector(const void __user 
*data,
        while (got < num_pages) {
                rc = get_user_pages_unlocked(
                    (unsigned long)data + ((unsigned long)got * PAGE_SIZE),
-                   num_pages - got, write_page, 0, pages + got);
+                   num_pages - got, pages + got, write_page ? FOLL_WRITE : 0);
                if (rc < 0)
                        break;
                BUG_ON(rc == 0);
-- 
2.10.0

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