298 lines
6.9 KiB
C
298 lines
6.9 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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/*
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* Called with mm->page_table_lock held to protect against other
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* threads/the swapper from ripping pte's out from under us.
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*/
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static int filemap_sync_pte(pte_t *ptep, struct vm_area_struct *vma,
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unsigned long address, unsigned int flags)
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{
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pte_t pte = *ptep;
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unsigned long pfn = pte_pfn(pte);
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struct page *page;
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if (pte_present(pte) && pfn_valid(pfn)) {
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page = pfn_to_page(pfn);
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if (!PageReserved(page) &&
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(ptep_clear_flush_dirty(vma, address, ptep) ||
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page_test_and_clear_dirty(page)))
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set_page_dirty(page);
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}
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return 0;
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}
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static int filemap_sync_pte_range(pmd_t * pmd,
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unsigned long address, unsigned long end,
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struct vm_area_struct *vma, unsigned int flags)
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{
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pte_t *pte;
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int error;
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if (pmd_none(*pmd))
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return 0;
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if (pmd_bad(*pmd)) {
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pmd_ERROR(*pmd);
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pmd_clear(pmd);
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return 0;
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}
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pte = pte_offset_map(pmd, address);
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if ((address & PMD_MASK) != (end & PMD_MASK))
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end = (address & PMD_MASK) + PMD_SIZE;
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error = 0;
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do {
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error |= filemap_sync_pte(pte, vma, address, flags);
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address += PAGE_SIZE;
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pte++;
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} while (address && (address < end));
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pte_unmap(pte - 1);
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return error;
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}
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static inline int filemap_sync_pmd_range(pud_t * pud,
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unsigned long address, unsigned long end,
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struct vm_area_struct *vma, unsigned int flags)
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{
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pmd_t * pmd;
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int error;
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if (pud_none(*pud))
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return 0;
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if (pud_bad(*pud)) {
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pud_ERROR(*pud);
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pud_clear(pud);
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return 0;
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}
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pmd = pmd_offset(pud, address);
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if ((address & PUD_MASK) != (end & PUD_MASK))
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end = (address & PUD_MASK) + PUD_SIZE;
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error = 0;
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do {
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error |= filemap_sync_pte_range(pmd, address, end, vma, flags);
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address = (address + PMD_SIZE) & PMD_MASK;
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pmd++;
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} while (address && (address < end));
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return error;
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}
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static inline int filemap_sync_pud_range(pgd_t *pgd,
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unsigned long address, unsigned long end,
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struct vm_area_struct *vma, unsigned int flags)
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{
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pud_t *pud;
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int error;
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if (pgd_none(*pgd))
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return 0;
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if (pgd_bad(*pgd)) {
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pgd_ERROR(*pgd);
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pgd_clear(pgd);
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return 0;
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}
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pud = pud_offset(pgd, address);
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if ((address & PGDIR_MASK) != (end & PGDIR_MASK))
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end = (address & PGDIR_MASK) + PGDIR_SIZE;
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error = 0;
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do {
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error |= filemap_sync_pmd_range(pud, address, end, vma, flags);
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address = (address + PUD_SIZE) & PUD_MASK;
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pud++;
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} while (address && (address < end));
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return error;
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}
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static int __filemap_sync(struct vm_area_struct *vma, unsigned long address,
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size_t size, unsigned int flags)
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{
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pgd_t *pgd;
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unsigned long end = address + size;
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unsigned long next;
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int i;
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int error = 0;
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/* Aquire the lock early; it may be possible to avoid dropping
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* and reaquiring it repeatedly.
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*/
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spin_lock(&vma->vm_mm->page_table_lock);
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pgd = pgd_offset(vma->vm_mm, address);
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flush_cache_range(vma, address, end);
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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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if (is_vm_hugetlb_page(vma))
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goto out;
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if (address >= end)
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BUG();
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for (i = pgd_index(address); i <= pgd_index(end-1); i++) {
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next = (address + PGDIR_SIZE) & PGDIR_MASK;
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if (next <= address || next > end)
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next = end;
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error |= filemap_sync_pud_range(pgd, address, next, vma, flags);
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address = next;
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pgd++;
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}
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/*
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* Why flush ? filemap_sync_pte already flushed the tlbs with the
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* dirty bits.
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*/
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flush_tlb_range(vma, end - size, end);
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out:
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spin_unlock(&vma->vm_mm->page_table_lock);
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return error;
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}
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#ifdef CONFIG_PREEMPT
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static int filemap_sync(struct vm_area_struct *vma, unsigned long address,
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size_t size, unsigned int flags)
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{
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const size_t chunk = 64 * 1024; /* bytes */
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int error = 0;
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while (size) {
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size_t sz = min(size, chunk);
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error |= __filemap_sync(vma, address, sz, flags);
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cond_resched();
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address += sz;
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size -= sz;
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}
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return error;
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}
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#else
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static int filemap_sync(struct vm_area_struct *vma, unsigned long address,
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size_t size, unsigned int flags)
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{
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return __filemap_sync(vma, address, size, flags);
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}
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#endif
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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 start, 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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ret = filemap_sync(vma, start, end-start, flags);
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if (!ret && (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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