2014-02-05 17:11:33 -07:00
|
|
|
#include <linux/export.h>
|
|
|
|
#include <linux/uio.h>
|
|
|
|
#include <linux/pagemap.h>
|
|
|
|
|
|
|
|
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
|
|
|
|
struct iov_iter *i)
|
|
|
|
{
|
|
|
|
size_t skip, copy, left, wanted;
|
|
|
|
const struct iovec *iov;
|
|
|
|
char __user *buf;
|
|
|
|
void *kaddr, *from;
|
|
|
|
|
|
|
|
if (unlikely(bytes > i->count))
|
|
|
|
bytes = i->count;
|
|
|
|
|
|
|
|
if (unlikely(!bytes))
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
wanted = bytes;
|
|
|
|
iov = i->iov;
|
|
|
|
skip = i->iov_offset;
|
|
|
|
buf = iov->iov_base + skip;
|
|
|
|
copy = min(bytes, iov->iov_len - skip);
|
|
|
|
|
|
|
|
if (!fault_in_pages_writeable(buf, copy)) {
|
|
|
|
kaddr = kmap_atomic(page);
|
|
|
|
from = kaddr + offset;
|
|
|
|
|
|
|
|
/* first chunk, usually the only one */
|
|
|
|
left = __copy_to_user_inatomic(buf, from, copy);
|
|
|
|
copy -= left;
|
|
|
|
skip += copy;
|
|
|
|
from += copy;
|
|
|
|
bytes -= copy;
|
|
|
|
|
|
|
|
while (unlikely(!left && bytes)) {
|
|
|
|
iov++;
|
|
|
|
buf = iov->iov_base;
|
|
|
|
copy = min(bytes, iov->iov_len);
|
|
|
|
left = __copy_to_user_inatomic(buf, from, copy);
|
|
|
|
copy -= left;
|
|
|
|
skip = copy;
|
|
|
|
from += copy;
|
|
|
|
bytes -= copy;
|
|
|
|
}
|
|
|
|
if (likely(!bytes)) {
|
|
|
|
kunmap_atomic(kaddr);
|
|
|
|
goto done;
|
|
|
|
}
|
|
|
|
offset = from - kaddr;
|
|
|
|
buf += copy;
|
|
|
|
kunmap_atomic(kaddr);
|
|
|
|
copy = min(bytes, iov->iov_len - skip);
|
|
|
|
}
|
|
|
|
/* Too bad - revert to non-atomic kmap */
|
|
|
|
kaddr = kmap(page);
|
|
|
|
from = kaddr + offset;
|
|
|
|
left = __copy_to_user(buf, from, copy);
|
|
|
|
copy -= left;
|
|
|
|
skip += copy;
|
|
|
|
from += copy;
|
|
|
|
bytes -= copy;
|
|
|
|
while (unlikely(!left && bytes)) {
|
|
|
|
iov++;
|
|
|
|
buf = iov->iov_base;
|
|
|
|
copy = min(bytes, iov->iov_len);
|
|
|
|
left = __copy_to_user(buf, from, copy);
|
|
|
|
copy -= left;
|
|
|
|
skip = copy;
|
|
|
|
from += copy;
|
|
|
|
bytes -= copy;
|
|
|
|
}
|
|
|
|
kunmap(page);
|
|
|
|
done:
|
|
|
|
i->count -= wanted - bytes;
|
|
|
|
i->nr_segs -= iov - i->iov;
|
|
|
|
i->iov = iov;
|
|
|
|
i->iov_offset = skip;
|
|
|
|
return wanted - bytes;
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(copy_page_to_iter);
|
|
|
|
|
|
|
|
static size_t __iovec_copy_from_user_inatomic(char *vaddr,
|
|
|
|
const struct iovec *iov, size_t base, size_t bytes)
|
|
|
|
{
|
|
|
|
size_t copied = 0, left = 0;
|
|
|
|
|
|
|
|
while (bytes) {
|
|
|
|
char __user *buf = iov->iov_base + base;
|
|
|
|
int copy = min(bytes, iov->iov_len - base);
|
|
|
|
|
|
|
|
base = 0;
|
|
|
|
left = __copy_from_user_inatomic(vaddr, buf, copy);
|
|
|
|
copied += copy;
|
|
|
|
bytes -= copy;
|
|
|
|
vaddr += copy;
|
|
|
|
iov++;
|
|
|
|
|
|
|
|
if (unlikely(left))
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
return copied - left;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Copy as much as we can into the page and return the number of bytes which
|
|
|
|
* were successfully copied. If a fault is encountered then return the number of
|
|
|
|
* bytes which were copied.
|
|
|
|
*/
|
|
|
|
size_t iov_iter_copy_from_user_atomic(struct page *page,
|
|
|
|
struct iov_iter *i, unsigned long offset, size_t bytes)
|
|
|
|
{
|
|
|
|
char *kaddr;
|
|
|
|
size_t copied;
|
|
|
|
|
|
|
|
kaddr = kmap_atomic(page);
|
|
|
|
if (likely(i->nr_segs == 1)) {
|
|
|
|
int left;
|
|
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
|
|
|
left = __copy_from_user_inatomic(kaddr + offset, buf, bytes);
|
|
|
|
copied = bytes - left;
|
|
|
|
} else {
|
|
|
|
copied = __iovec_copy_from_user_inatomic(kaddr + offset,
|
|
|
|
i->iov, i->iov_offset, bytes);
|
|
|
|
}
|
|
|
|
kunmap_atomic(kaddr);
|
|
|
|
|
|
|
|
return copied;
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
|
|
|
|
|
|
|
|
void iov_iter_advance(struct iov_iter *i, size_t bytes)
|
|
|
|
{
|
|
|
|
BUG_ON(i->count < bytes);
|
|
|
|
|
|
|
|
if (likely(i->nr_segs == 1)) {
|
|
|
|
i->iov_offset += bytes;
|
|
|
|
i->count -= bytes;
|
|
|
|
} else {
|
|
|
|
const struct iovec *iov = i->iov;
|
|
|
|
size_t base = i->iov_offset;
|
|
|
|
unsigned long nr_segs = i->nr_segs;
|
|
|
|
|
|
|
|
/*
|
|
|
|
* The !iov->iov_len check ensures we skip over unlikely
|
|
|
|
* zero-length segments (without overruning the iovec).
|
|
|
|
*/
|
|
|
|
while (bytes || unlikely(i->count && !iov->iov_len)) {
|
|
|
|
int copy;
|
|
|
|
|
|
|
|
copy = min(bytes, iov->iov_len - base);
|
|
|
|
BUG_ON(!i->count || i->count < copy);
|
|
|
|
i->count -= copy;
|
|
|
|
bytes -= copy;
|
|
|
|
base += copy;
|
|
|
|
if (iov->iov_len == base) {
|
|
|
|
iov++;
|
|
|
|
nr_segs--;
|
|
|
|
base = 0;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
i->iov = iov;
|
|
|
|
i->iov_offset = base;
|
|
|
|
i->nr_segs = nr_segs;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(iov_iter_advance);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Fault in the first iovec of the given iov_iter, to a maximum length
|
|
|
|
* of bytes. Returns 0 on success, or non-zero if the memory could not be
|
|
|
|
* accessed (ie. because it is an invalid address).
|
|
|
|
*
|
|
|
|
* writev-intensive code may want this to prefault several iovecs -- that
|
|
|
|
* would be possible (callers must not rely on the fact that _only_ the
|
|
|
|
* first iovec will be faulted with the current implementation).
|
|
|
|
*/
|
|
|
|
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
|
|
|
|
{
|
|
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
|
|
|
bytes = min(bytes, i->iov->iov_len - i->iov_offset);
|
|
|
|
return fault_in_pages_readable(buf, bytes);
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(iov_iter_fault_in_readable);
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Return the count of just the current iov_iter segment.
|
|
|
|
*/
|
|
|
|
size_t iov_iter_single_seg_count(const struct iov_iter *i)
|
|
|
|
{
|
|
|
|
const struct iovec *iov = i->iov;
|
|
|
|
if (i->nr_segs == 1)
|
|
|
|
return i->count;
|
|
|
|
else
|
|
|
|
return min(i->count, iov->iov_len - i->iov_offset);
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(iov_iter_single_seg_count);
|
2014-03-05 11:50:45 -07:00
|
|
|
|
|
|
|
unsigned long iov_iter_alignment(const struct iov_iter *i)
|
|
|
|
{
|
|
|
|
const struct iovec *iov = i->iov;
|
|
|
|
unsigned long res;
|
|
|
|
size_t size = i->count;
|
|
|
|
size_t n;
|
|
|
|
|
|
|
|
if (!size)
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
res = (unsigned long)iov->iov_base + i->iov_offset;
|
|
|
|
n = iov->iov_len - i->iov_offset;
|
|
|
|
if (n >= size)
|
|
|
|
return res | size;
|
|
|
|
size -= n;
|
|
|
|
res |= n;
|
|
|
|
while (size > (++iov)->iov_len) {
|
|
|
|
res |= (unsigned long)iov->iov_base | iov->iov_len;
|
|
|
|
size -= iov->iov_len;
|
|
|
|
}
|
|
|
|
res |= (unsigned long)iov->iov_base | size;
|
|
|
|
return res;
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(iov_iter_alignment);
|
2014-03-05 17:28:09 -07:00
|
|
|
|
|
|
|
void iov_iter_init(struct iov_iter *i, int direction,
|
|
|
|
const struct iovec *iov, unsigned long nr_segs,
|
|
|
|
size_t count)
|
|
|
|
{
|
|
|
|
/* It will get better. Eventually... */
|
|
|
|
if (segment_eq(get_fs(), KERNEL_DS))
|
|
|
|
direction |= REQ_KERNEL;
|
|
|
|
i->type = direction;
|
|
|
|
i->iov = iov;
|
|
|
|
i->nr_segs = nr_segs;
|
|
|
|
i->iov_offset = 0;
|
|
|
|
i->count = count;
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(iov_iter_init);
|
2014-03-15 02:05:57 -06:00
|
|
|
|
|
|
|
ssize_t iov_iter_get_pages(struct iov_iter *i,
|
|
|
|
struct page **pages, size_t maxsize,
|
|
|
|
size_t *start)
|
|
|
|
{
|
|
|
|
size_t offset = i->iov_offset;
|
|
|
|
const struct iovec *iov = i->iov;
|
|
|
|
size_t len;
|
|
|
|
unsigned long addr;
|
|
|
|
int n;
|
|
|
|
int res;
|
|
|
|
|
|
|
|
len = iov->iov_len - offset;
|
|
|
|
if (len > i->count)
|
|
|
|
len = i->count;
|
|
|
|
if (len > maxsize)
|
|
|
|
len = maxsize;
|
|
|
|
addr = (unsigned long)iov->iov_base + offset;
|
|
|
|
len += *start = addr & (PAGE_SIZE - 1);
|
|
|
|
addr &= ~(PAGE_SIZE - 1);
|
|
|
|
n = (len + PAGE_SIZE - 1) / PAGE_SIZE;
|
|
|
|
res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, pages);
|
|
|
|
if (unlikely(res < 0))
|
|
|
|
return res;
|
|
|
|
return (res == n ? len : res * PAGE_SIZE) - *start;
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(iov_iter_get_pages);
|
2014-03-18 23:16:16 -06:00
|
|
|
|
|
|
|
int iov_iter_npages(const struct iov_iter *i, int maxpages)
|
|
|
|
{
|
|
|
|
size_t offset = i->iov_offset;
|
|
|
|
size_t size = i->count;
|
|
|
|
const struct iovec *iov = i->iov;
|
|
|
|
int npages = 0;
|
|
|
|
int n;
|
|
|
|
|
|
|
|
for (n = 0; size && n < i->nr_segs; n++, iov++) {
|
|
|
|
unsigned long addr = (unsigned long)iov->iov_base + offset;
|
|
|
|
size_t len = iov->iov_len - offset;
|
|
|
|
offset = 0;
|
|
|
|
if (unlikely(!len)) /* empty segment */
|
|
|
|
continue;
|
|
|
|
if (len > size)
|
|
|
|
len = size;
|
|
|
|
npages += (addr + len + PAGE_SIZE - 1) / PAGE_SIZE
|
|
|
|
- addr / PAGE_SIZE;
|
|
|
|
if (npages >= maxpages) /* don't bother going further */
|
|
|
|
return maxpages;
|
|
|
|
size -= len;
|
|
|
|
offset = 0;
|
|
|
|
}
|
|
|
|
return min(npages, maxpages);
|
|
|
|
}
|
|
|
|
EXPORT_SYMBOL(iov_iter_npages);
|