/* * linux/mm/msync.c * * Copyright (C) 1994-1999 Linus Torvalds */ /* * The msync() system call. */ #include <linux/slab.h> #include <linux/pagemap.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/mman.h> #include <linux/hugetlb.h> #include <linux/writeback.h> #include <linux/file.h> #include <linux/syscalls.h> #include <asm/pgtable.h> #include <asm/tlbflush.h> static unsigned long msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end) { pte_t *pte; spinlock_t *ptl; int progress = 0; unsigned long ret = 0; again: pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); do { struct page *page; if (progress >= 64) { progress = 0; if (need_resched() || need_lockbreak(ptl)) break; } progress++; if (!pte_present(*pte)) continue; if (!pte_maybe_dirty(*pte)) continue; page = vm_normal_page(vma, addr, *pte); if (!page) continue; if (ptep_clear_flush_dirty(vma, addr, pte) || page_test_and_clear_dirty(page)) ret += set_page_dirty(page); progress += 3; } while (pte++, addr += PAGE_SIZE, addr != end); pte_unmap_unlock(pte - 1, ptl); cond_resched(); if (addr != end) goto again; return ret; } static inline unsigned long msync_pmd_range(struct vm_area_struct *vma, pud_t *pud, unsigned long addr, unsigned long end) { pmd_t *pmd; unsigned long next; unsigned long ret = 0; pmd = pmd_offset(pud, addr); do { next = pmd_addr_end(addr, end); if (pmd_none_or_clear_bad(pmd)) continue; ret += msync_pte_range(vma, pmd, addr, next); } while (pmd++, addr = next, addr != end); return ret; } static inline unsigned long msync_pud_range(struct vm_area_struct *vma, pgd_t *pgd, unsigned long addr, unsigned long end) { pud_t *pud; unsigned long next; unsigned long ret = 0; pud = pud_offset(pgd, addr); do { next = pud_addr_end(addr, end); if (pud_none_or_clear_bad(pud)) continue; ret += msync_pmd_range(vma, pud, addr, next); } while (pud++, addr = next, addr != end); return ret; } static unsigned long msync_page_range(struct vm_area_struct *vma, unsigned long addr, unsigned long end) { pgd_t *pgd; unsigned long next; unsigned long ret = 0; /* 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 (vma->vm_flags & VM_HUGETLB) return 0; BUG_ON(addr >= end); pgd = pgd_offset(vma->vm_mm, addr); flush_cache_range(vma, addr, end); do { next = pgd_addr_end(addr, end); if (pgd_none_or_clear_bad(pgd)) continue; ret += msync_pud_range(vma, pgd, addr, next); } while (pgd++, addr = next, addr != end); return ret; } /* * 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 by _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, unsigned long *nr_pages_dirtied) { struct file *file = vma->vm_file; if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED)) return -EBUSY; if (file && (vma->vm_flags & VM_SHARED)) *nr_pages_dirtied = msync_page_range(vma, addr, end); return 0; } asmlinkage long sys_msync(unsigned long start, size_t len, int flags) { unsigned long end; struct vm_area_struct *vma; int unmapped_error = 0; int error = -EINVAL; int done = 0; 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. */ down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, start); if (!vma) { error = -ENOMEM; goto out_unlock; } do { unsigned long nr_pages_dirtied = 0; struct file *file; /* 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, &nr_pages_dirtied); if (error) goto out_unlock; } error = unmapped_error; done = 1; } else { /* Here vma->vm_start <= start < vma->vm_end < end. */ error = msync_interval(vma, start, vma->vm_end, flags, &nr_pages_dirtied); if (error) goto out_unlock; } file = vma->vm_file; start = vma->vm_end; if ((flags & MS_ASYNC) && file && nr_pages_dirtied) { get_file(file); up_read(¤t->mm->mmap_sem); balance_dirty_pages_ratelimited_nr(file->f_mapping, nr_pages_dirtied); fput(file); down_read(¤t->mm->mmap_sem); vma = find_vma(current->mm, start); } else if ((flags & MS_SYNC) && file && (vma->vm_flags & VM_SHARED)) { get_file(file); up_read(¤t->mm->mmap_sem); error = do_fsync(file, 0); fput(file); down_read(¤t->mm->mmap_sem); if (error) goto out_unlock; vma = find_vma(current->mm, start); } else { vma = vma->vm_next; } } while (vma && !done); out_unlock: up_read(¤t->mm->mmap_sem); out: return error; }