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/*
* linux/mm/msync.c
*
* Copyright (C) 1994-1999 Linus Torvalds
*/
/*
* The msync() system call.
*/
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/hugetlb.h>
#include <linux/syscalls.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
/*
* Called with mm->page_table_lock held to protect against other
* threads/the swapper from ripping pte's out from under us.
*/
static void msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, unsigned long end)
{
pte_t *pte;
int progress = 0;
again:
pte = pte_offset_map(pmd, addr);
do {
unsigned long pfn;
struct page *page;
if (progress >= 64) {
progress = 0;
if (need_resched() ||
need_lockbreak(&vma->vm_mm->page_table_lock))
break;
}
progress++;
if (!pte_present(*pte))
continue;
if (!pte_maybe_dirty(*pte))
continue;
pfn = pte_pfn(*pte);
if (!pfn_valid(pfn))
continue;
page = pfn_to_page(pfn);
if (PageReserved(page))
continue;
if (ptep_clear_flush_dirty(vma, addr, pte) ||
page_test_and_clear_dirty(page))
set_page_dirty(page);
progress += 3;
} while (pte++, addr += PAGE_SIZE, addr != end);
pte_unmap(pte - 1);
cond_resched_lock(&vma->vm_mm->page_table_lock);
if (addr != end)
goto again;
}
static inline void msync_pmd_range(struct vm_area_struct *vma, pud_t *pud,
unsigned long addr, unsigned long end)
{
pmd_t *pmd;
unsigned long next;
pmd = pmd_offset(pud, addr);
do {
next = pmd_addr_end(addr, end);
if (pmd_none_or_clear_bad(pmd))
continue;
msync_pte_range(vma, pmd, addr, next);
} while (pmd++, addr = next, addr != end);
}
static inline void msync_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
unsigned long addr, unsigned long end)
{
pud_t *pud;
unsigned long next;
pud = pud_offset(pgd, addr);
do {
next = pud_addr_end(addr, end);
if (pud_none_or_clear_bad(pud))
continue;
msync_pmd_range(vma, pud, addr, next);
} while (pud++, addr = next, addr != end);
}
static void msync_page_range(struct vm_area_struct *vma,
unsigned long addr, unsigned long end)
{
struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
unsigned long next;
/* For hugepages we can't go walking the page table normally,
* but that's ok, hugetlbfs is memory based, so we don't need
* to do anything more on an msync() */
if (is_vm_hugetlb_page(vma))
return;
BUG_ON(addr >= end);
pgd = pgd_offset(mm, addr);
flush_cache_range(vma, addr, end);
spin_lock(&mm->page_table_lock);
do {
next = pgd_addr_end(addr, end);
if (pgd_none_or_clear_bad(pgd))
continue;
msync_pud_range(vma, pgd, addr, next);
} while (pgd++, addr = next, addr != end);
spin_unlock(&mm->page_table_lock);
}
/*
* MS_SYNC syncs the entire file - including mappings.
*
* MS_ASYNC does not start I/O (it used to, up to 2.5.67). Instead, it just
* marks the relevant pages dirty. The application may now run fsync() to
* write out the dirty pages and wait on the writeout and check the result.
* Or the application may run fadvise(FADV_DONTNEED) against the fd to start
* async writeout immediately.
* So my _not_ starting I/O in MS_ASYNC we provide complete flexibility to
* applications.
*/
static int msync_interval(struct vm_area_struct *vma,
unsigned long addr, unsigned long end, int flags)
{
int ret = 0;
struct file *file = vma->vm_file;
if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
return -EBUSY;
if (file && (vma->vm_flags & VM_SHARED)) {
msync_page_range(vma, addr, end);
if (flags & MS_SYNC) {
struct address_space *mapping = file->f_mapping;
int err;
ret = filemap_fdatawrite(mapping);
if (file->f_op && file->f_op->fsync) {
/*
* We don't take i_sem here because mmap_sem
* is already held.
*/
err = file->f_op->fsync(file,file->f_dentry,1);
if (err && !ret)
ret = err;
}
err = filemap_fdatawait(mapping);
if (!ret)
ret = err;
}
}
return ret;
}
asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
{
unsigned long end;
struct vm_area_struct *vma;
int unmapped_error, error = -EINVAL;
if (flags & MS_SYNC)
current->flags |= PF_SYNCWRITE;
down_read(¤t->mm->mmap_sem);
if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
goto out;
if (start & ~PAGE_MASK)
goto out;
if ((flags & MS_ASYNC) && (flags & MS_SYNC))
goto out;
error = -ENOMEM;
len = (len + ~PAGE_MASK) & PAGE_MASK;
end = start + len;
if (end < start)
goto out;
error = 0;
if (end == start)
goto out;
/*
* If the interval [start,end) covers some unmapped address ranges,
* just ignore them, but return -ENOMEM at the end.
*/
vma = find_vma(current->mm, start);
unmapped_error = 0;
for (;;) {
/* Still start < end. */
error = -ENOMEM;
if (!vma)
goto out;
/* Here start < vma->vm_end. */
if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
}
/* Here vma->vm_start <= start < vma->vm_end. */
if (end <= vma->vm_end) {
if (start < end) {
error = msync_interval(vma, start, end, flags);
if (error)
goto out;
}
error = unmapped_error;
goto out;
}
/* Here vma->vm_start <= start < vma->vm_end < end. */
error = msync_interval(vma, start, vma->vm_end, flags);
if (error)
goto out;
start = vma->vm_end;
vma = vma->vm_next;
}
out:
up_read(¤t->mm->mmap_sem);
current->flags &= ~PF_SYNCWRITE;
return error;
}
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