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get rid of separate multipage fault-in primitives

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* the only remaining callers of "short" fault-ins are just as happy with generic
variants (both in lib/iov_iter.c); switch them to multipage variants, kill the
"short" ones
* rename the multipage variants to now available plain ones.
* get rid of compat macro defining iov_iter_fault_in_multipage_readable by
expanding it in its only user.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2016-09-17 18:02:44 -04:00
parent 08895a8b6b
commit 4bce9f6ee8
7 changed files with 9 additions and 61 deletions
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54
include/linux/pagemap.h
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@ -518,58 +518,9 @@ void page_endio(struct page *page, bool is_write, int err);
extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter);
/*
* Fault one or two userspace pages into pagetables.
* Return -EINVAL if more than two pages would be needed.
* Return non-zero on a fault.
* Fault everything in given userspace address range in.
*/
static inline int fault_in_pages_writeable(char __user *uaddr, int size)
{
int span, ret;
if (unlikely(size == 0))
return 0;
span = offset_in_page(uaddr) + size;
if (span > 2 * PAGE_SIZE)
return -EINVAL;
/*
* Writing zeroes into userspace here is OK, because we know that if
* the zero gets there, we'll be overwriting it.
*/
ret = __put_user(0, uaddr);
if (ret == 0 && span > PAGE_SIZE)
ret = __put_user(0, uaddr + size - 1);
return ret;
}
static inline int fault_in_pages_readable(const char __user *uaddr, int size)
{
volatile char c;
int ret;
if (unlikely(size == 0))
return 0;
ret = __get_user(c, uaddr);
if (ret == 0) {
const char __user *end = uaddr + size - 1;
if (((unsigned long)uaddr & PAGE_MASK) !=
((unsigned long)end & PAGE_MASK)) {
ret = __get_user(c, end);
(void)c;
}
}
return ret;
}
/*
* Multipage variants of the above prefault helpers, useful if more than
* PAGE_SIZE of data needs to be prefaulted. These are separate from the above
* functions (which only handle up to PAGE_SIZE) to avoid clobbering the
* filemap.c hotpaths.
*/
static inline int fault_in_multipages_writeable(char __user *uaddr, int size)
{
char __user *end = uaddr + size - 1;
@ -596,8 +547,7 @@ static inline int fault_in_multipages_writeable(char __user *uaddr, int size)
return 0;
}
static inline int fault_in_multipages_readable(const char __user *uaddr,
int size)
static inline int fault_in_pages_readable(const char __user *uaddr, int size)
{
volatile char c;
const char __user *end = uaddr + size - 1;