*
* started by Ingo Molnar, Copyright (C) 2002, 2003
*/
-
+#include <linux/backing-dev.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/file.h>
}
-/***
- * sys_remap_file_pages - remap arbitrary pages of a shared backing store
- * file within an existing vma.
+/**
+ * sys_remap_file_pages - remap arbitrary pages of an existing VM_SHARED vma
* @start: start of the remapped virtual memory range
* @size: size of the remapped virtual memory range
- * @prot: new protection bits of the range
- * @pgoff: to be mapped page of the backing store file
+ * @prot: new protection bits of the range (see NOTE)
+ * @pgoff: to-be-mapped page of the backing store file
* @flags: 0 or MAP_NONBLOCKED - the later will cause no IO.
*
- * this syscall works purely via pagetables, so it's the most efficient
+ * sys_remap_file_pages remaps arbitrary pages of an existing VM_SHARED vma
+ * (shared backing store file).
+ *
+ * This syscall works purely via pagetables, so it's the most efficient
* way to map the same (large) file into a given virtual window. Unlike
* mmap()/mremap() it does not create any new vmas. The new mappings are
* also safe across swapout.
*
- * NOTE: the 'prot' parameter right now is ignored, and the vma's default
- * protection is used. Arbitrary protections might be implemented in the
- * future.
+ * NOTE: the 'prot' parameter right now is ignored (but must be zero),
+ * and the vma's default protection is used. Arbitrary protections
+ * might be implemented in the future.
*/
asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
- unsigned long __prot, unsigned long pgoff, unsigned long flags)
+ unsigned long prot, unsigned long pgoff, unsigned long flags)
{
struct mm_struct *mm = current->mm;
struct address_space *mapping;
int err = -EINVAL;
int has_write_lock = 0;
- if (__prot)
+ if (prot)
return err;
/*
* Sanitize the syscall parameters:
if (vma->vm_private_data && !(vma->vm_flags & VM_NONLINEAR))
goto out;
- if (!vma->vm_flags & VM_CAN_NONLINEAR)
+ if (!(vma->vm_flags & VM_CAN_NONLINEAR))
goto out;
if (end <= start || start < vma->vm_start || end > vma->vm_end)
goto retry;
}
mapping = vma->vm_file->f_mapping;
+ /*
+ * page_mkclean doesn't work on nonlinear vmas, so if
+ * dirty pages need to be accounted, emulate with linear
+ * vmas.
+ */
+ if (mapping_cap_account_dirty(mapping)) {
+ unsigned long addr;
+ struct file *file = vma->vm_file;
+
+ flags &= MAP_NONBLOCK;
+ get_file(file);
+ addr = mmap_region(file, start, size,
+ flags, vma->vm_flags, pgoff, 1);
+ fput(file);
+ if (IS_ERR_VALUE(addr)) {
+ err = addr;
+ } else {
+ BUG_ON(addr != start);
+ err = 0;
+ }
+ goto out;
+ }
spin_lock(&mapping->i_mmap_lock);
flush_dcache_mmap_lock(mapping);
vma->vm_flags |= VM_NONLINEAR;