/* *	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(&current->mm->mmap_sem);	if (flags & MS_SYNC)		current->flags |= PF_SYNCWRITE;	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(&current->mm->mmap_sem);			balance_dirty_pages_ratelimited_nr(file->f_mapping,							nr_pages_dirtied);			fput(file);			down_read(&current->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(&current->mm->mmap_sem);			error = do_fsync(file, 0);			fput(file);			down_read(&current->mm->mmap_sem);			if (error)				goto out_unlock;			vma = find_vma(current->mm, start);		} else {			vma = vma->vm_next;		}	} while (vma && !done);out_unlock:	current->flags &= ~PF_SYNCWRITE;	up_read(&current->mm->mmap_sem);out:	return error;}