/* *	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 sync_pte_range(struct vm_area_struct *vma, pmd_t *pmd,				unsigned long addr, unsigned long end){	pte_t *pte; 	pte = pte_offset_map(pmd, addr);	do {		unsigned long pfn;		struct page *page; 		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);	} while (pte++, addr += PAGE_SIZE, addr != end);	pte_unmap(pte - 1);} static inline void sync_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;		sync_pte_range(vma, pmd, addr, next);	} while (pmd++, addr = next, addr != end);} static inline void sync_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;		sync_pmd_range(vma, pud, addr, next);	} while (pud++, addr = next, addr != end);} static void sync_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;		sync_pud_range(vma, pgd, addr, next);	} while (pgd++, addr = next, addr != end);	spin_unlock(&mm->page_table_lock);} #ifdef CONFIG_PREEMPTstatic inline void filemap_sync(struct vm_area_struct *vma,				unsigned long addr, unsigned long end){	const size_t chunk = 64 * 1024;	/* bytes */	unsigned long next; 	do {		next = addr + chunk;		if (next > end || next < addr)			next = end;		sync_page_range(vma, addr, next);		cond_resched();	} while (addr = next, addr != end);}#elsestatic inline void filemap_sync(struct vm_area_struct *vma,				unsigned long addr, unsigned long end){	sync_page_range(vma, addr, end);}#endif /* * 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)) {		filemap_sync(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(&current->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(&current->mm->mmap_sem);	current->flags &= ~PF_SYNCWRITE;	return error;}