VM: add "vm_mmap()" helper function

This continues the theme started with vm_brk() and vm_munmap():
vm_mmap() does the same thing as do_mmap(), but additionally does the
required VM locking.

This uninlines (and rewrites it to be clearer) do_mmap(), which sadly
duplicates it in mm/mmap.c and mm/nommu.c.  But that way we don't have
to export our internal do_mmap_pgoff() function.

Some day we hopefully don't have to export do_mmap() either, if all
modular users can become the simpler vm_mmap() instead.  We're actually
very close to that already, with the notable exception of the (broken)
use in i810, and a couple of stragglers in binfmt_elf.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 9 deletions

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 024d20ee3ca3..6b2daf99fab8 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -542,10 +542,8 @@ static int load_flat_file(struct linux_binprm * bprm,
                  */
                 DBG_FLT("BINFMT_FLAT: ROM mapping of file (we hope)\n");
 
-                down_write(&current->mm->mmap_sem);
-                textpos = do_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
+                textpos = vm_mmap(bprm->file, 0, text_len, PROT_READ|PROT_EXEC,
                                   MAP_PRIVATE|MAP_EXECUTABLE, 0);
-                up_write(&current->mm->mmap_sem);
                 if (!textpos || IS_ERR_VALUE(textpos)) {
                         if (!textpos)
                                 textpos = (unsigned long) -ENOMEM;
@@ -556,10 +554,8 @@ static int load_flat_file(struct linux_binprm * bprm,
 
                 len = data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
                 len = PAGE_ALIGN(len);
-                down_write(&current->mm->mmap_sem);
-                realdatastart = do_mmap(0, 0, len,
+                realdatastart = vm_mmap(0, 0, len,
                         PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, 0);
-                up_write(&current->mm->mmap_sem);
 
                 if (realdatastart == 0 || IS_ERR_VALUE(realdatastart)) {
                         if (!realdatastart)
@@ -603,10 +599,8 @@ static int load_flat_file(struct linux_binprm * bprm,
 
                 len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(unsigned long);
                 len = PAGE_ALIGN(len);
-                down_write(&current->mm->mmap_sem);
-                textpos = do_mmap(0, 0, len,
+                textpos = vm_mmap(0, 0, len,
                         PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);
-                up_write(&current->mm->mmap_sem);
 
                 if (!textpos || IS_ERR_VALUE(textpos)) {
                         if (!textpos)