/* *	linux/mm/filemap.h * * Copyright (C) 1994-1999  Linus Torvalds */ #ifndef __FILEMAP_H#define __FILEMAP_H #include <linux/types.h>#include <linux/fs.h>#include <linux/mm.h>#include <linux/highmem.h>#include <linux/uio.h>#include <linux/uaccess.h> size_t__filemap_copy_from_user_iovec_inatomic(char *vaddr,					const struct iovec *iov,					size_t base,					size_t bytes); /* * Copy as much as we can into the page and return the number of bytes which * were sucessfully copied.  If a fault is encountered then clear the page * out to (offset+bytes) and return the number of bytes which were copied. * * NOTE: For this to work reliably we really want copy_from_user_inatomic_nocache * to *NOT* zero any tail of the buffer that it failed to copy.  If it does, * and if the following non-atomic copy succeeds, then there is a small window * where the target page contains neither the data before the write, nor the * data after the write (it contains zero).  A read at this time will see * data that is inconsistent with any ordering of the read and the write. * (This has been detected in practice). */static inline size_tfilemap_copy_from_user(struct page *page, unsigned long offset,			const char __user *buf, unsigned bytes){	char *kaddr;	int left; 	kaddr = kmap_atomic(page, KM_USER0);	left = __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes);	kunmap_atomic(kaddr, KM_USER0); 	if (left != 0) {		/* Do it the slow way */		kaddr = kmap(page);		left = __copy_from_user_nocache(kaddr + offset, buf, bytes);		kunmap(page);	}	return bytes - left;} /* * This has the same sideeffects and return value as filemap_copy_from_user(). * The difference is that on a fault we need to memset the remainder of the * page (out to offset+bytes), to emulate filemap_copy_from_user()'s * single-segment behaviour. */static inline size_tfilemap_copy_from_user_iovec(struct page *page, unsigned long offset,			const struct iovec *iov, size_t base, size_t bytes){	char *kaddr;	size_t copied; 	kaddr = kmap_atomic(page, KM_USER0);	copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset, iov,							 base, bytes);	kunmap_atomic(kaddr, KM_USER0);	if (copied != bytes) {		kaddr = kmap(page);		copied = __filemap_copy_from_user_iovec_inatomic(kaddr + offset, iov,								 base, bytes);		if (bytes - copied)			memset(kaddr + offset + copied, 0, bytes - copied);		kunmap(page);	}	return copied;} static inline voidfilemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes){	const struct iovec *iov = *iovp;	size_t base = *basep; 	do {		int copy = min(bytes, iov->iov_len - base); 		bytes -= copy;		base += copy;		if (iov->iov_len == base) {			iov++;			base = 0;		}	} while (bytes);	*iovp = iov;	*basep = base;}#endif