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6aab341e0a
This replaces the (in my opinion horrible) VM_UNMAPPED logic with very explicit support for a "remapped page range" aka VM_PFNMAP. It allows a VM area to contain an arbitrary range of page table entries that the VM never touches, and never considers to be normal pages. Any user of "remap_pfn_range()" automatically gets this new functionality, and doesn't even have to mark the pages reserved or indeed mark them any other way. It just works. As a side effect, doing mmap() on /dev/mem works for arbitrary ranges. Sparc update from David in the next commit. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
217 lines
5.0 KiB
C
217 lines
5.0 KiB
C
/*
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* linux/mm/msync.c
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*
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* Copyright (C) 1994-1999 Linus Torvalds
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*/
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/*
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* The msync() system call.
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*/
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#include <linux/slab.h>
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#include <linux/pagemap.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/hugetlb.h>
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#include <linux/syscalls.h>
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#include <asm/pgtable.h>
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#include <asm/tlbflush.h>
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static void msync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
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unsigned long addr, unsigned long end)
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{
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pte_t *pte;
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spinlock_t *ptl;
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int progress = 0;
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again:
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pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
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do {
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struct page *page;
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if (progress >= 64) {
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progress = 0;
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if (need_resched() || need_lockbreak(ptl))
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break;
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}
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progress++;
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if (!pte_present(*pte))
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continue;
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if (!pte_maybe_dirty(*pte))
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continue;
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page = vm_normal_page(vma, addr, *pte);
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if (!page)
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continue;
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if (ptep_clear_flush_dirty(vma, addr, pte) ||
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page_test_and_clear_dirty(page))
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set_page_dirty(page);
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progress += 3;
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} while (pte++, addr += PAGE_SIZE, addr != end);
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pte_unmap_unlock(pte - 1, ptl);
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cond_resched();
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if (addr != end)
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goto again;
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}
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static inline void msync_pmd_range(struct vm_area_struct *vma, pud_t *pud,
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unsigned long addr, unsigned long end)
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{
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pmd_t *pmd;
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unsigned long next;
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pmd = pmd_offset(pud, addr);
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do {
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next = pmd_addr_end(addr, end);
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if (pmd_none_or_clear_bad(pmd))
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continue;
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msync_pte_range(vma, pmd, addr, next);
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} while (pmd++, addr = next, addr != end);
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}
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static inline void msync_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
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unsigned long addr, unsigned long end)
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{
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pud_t *pud;
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unsigned long next;
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pud = pud_offset(pgd, addr);
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do {
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next = pud_addr_end(addr, end);
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if (pud_none_or_clear_bad(pud))
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continue;
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msync_pmd_range(vma, pud, addr, next);
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} while (pud++, addr = next, addr != end);
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}
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static void msync_page_range(struct vm_area_struct *vma,
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unsigned long addr, unsigned long end)
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{
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pgd_t *pgd;
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unsigned long next;
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/* For hugepages we can't go walking the page table normally,
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* but that's ok, hugetlbfs is memory based, so we don't need
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* to do anything more on an msync().
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*/
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if (vma->vm_flags & VM_HUGETLB)
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return;
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BUG_ON(addr >= end);
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pgd = pgd_offset(vma->vm_mm, addr);
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flush_cache_range(vma, addr, end);
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do {
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next = pgd_addr_end(addr, end);
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if (pgd_none_or_clear_bad(pgd))
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continue;
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msync_pud_range(vma, pgd, addr, next);
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} while (pgd++, addr = next, addr != end);
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}
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/*
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* MS_SYNC syncs the entire file - including mappings.
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*
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* MS_ASYNC does not start I/O (it used to, up to 2.5.67). Instead, it just
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* marks the relevant pages dirty. The application may now run fsync() to
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* write out the dirty pages and wait on the writeout and check the result.
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* Or the application may run fadvise(FADV_DONTNEED) against the fd to start
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* async writeout immediately.
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* So my _not_ starting I/O in MS_ASYNC we provide complete flexibility to
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* applications.
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*/
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static int msync_interval(struct vm_area_struct *vma,
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unsigned long addr, unsigned long end, int flags)
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{
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int ret = 0;
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struct file *file = vma->vm_file;
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if ((flags & MS_INVALIDATE) && (vma->vm_flags & VM_LOCKED))
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return -EBUSY;
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if (file && (vma->vm_flags & VM_SHARED)) {
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msync_page_range(vma, addr, end);
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if (flags & MS_SYNC) {
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struct address_space *mapping = file->f_mapping;
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int err;
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ret = filemap_fdatawrite(mapping);
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if (file->f_op && file->f_op->fsync) {
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/*
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* We don't take i_sem here because mmap_sem
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* is already held.
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*/
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err = file->f_op->fsync(file,file->f_dentry,1);
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if (err && !ret)
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ret = err;
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}
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err = filemap_fdatawait(mapping);
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if (!ret)
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ret = err;
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}
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}
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return ret;
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}
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asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
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{
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unsigned long end;
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struct vm_area_struct *vma;
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int unmapped_error, error = -EINVAL;
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if (flags & MS_SYNC)
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current->flags |= PF_SYNCWRITE;
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down_read(¤t->mm->mmap_sem);
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if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
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goto out;
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if (start & ~PAGE_MASK)
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goto out;
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if ((flags & MS_ASYNC) && (flags & MS_SYNC))
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goto out;
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error = -ENOMEM;
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len = (len + ~PAGE_MASK) & PAGE_MASK;
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end = start + len;
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if (end < start)
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goto out;
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error = 0;
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if (end == start)
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goto out;
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/*
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* If the interval [start,end) covers some unmapped address ranges,
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* just ignore them, but return -ENOMEM at the end.
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*/
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vma = find_vma(current->mm, start);
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unmapped_error = 0;
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for (;;) {
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/* Still start < end. */
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error = -ENOMEM;
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if (!vma)
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goto out;
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/* Here start < vma->vm_end. */
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if (start < vma->vm_start) {
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unmapped_error = -ENOMEM;
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start = vma->vm_start;
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}
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/* Here vma->vm_start <= start < vma->vm_end. */
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if (end <= vma->vm_end) {
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if (start < end) {
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error = msync_interval(vma, start, end, flags);
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if (error)
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goto out;
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}
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error = unmapped_error;
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goto out;
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}
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/* Here vma->vm_start <= start < vma->vm_end < end. */
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error = msync_interval(vma, start, vma->vm_end, flags);
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if (error)
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goto out;
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start = vma->vm_end;
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vma = vma->vm_next;
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}
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out:
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up_read(¤t->mm->mmap_sem);
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current->flags &= ~PF_SYNCWRITE;
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return error;
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}
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