- 根目录:
- mm
- iov_iter.c
#include <linux/export.h>
#include <linux/uio.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
static size_t copy_to_iter_iovec(void *from, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, left, wanted;
const struct iovec *iov;
char __user *buf;
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);
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;
}
if (skip == iov->iov_len) {
iov++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= iov - i->iov;
i->iov = iov;
i->iov_offset = skip;
return wanted - bytes;
}
static size_t copy_from_iter_iovec(void *to, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, left, wanted;
const struct iovec *iov;
char __user *buf;
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);
left = __copy_from_user(to, buf, copy);
copy -= left;
skip += copy;
to += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __copy_from_user(to, buf, copy);
copy -= left;
skip = copy;
to += copy;
bytes -= copy;
}
if (skip == iov->iov_len) {
iov++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= iov - i->iov;
i->iov = iov;
i->iov_offset = skip;
return wanted - bytes;
}
static size_t copy_page_to_iter_iovec(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:
if (skip == iov->iov_len) {
iov++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= iov - i->iov;
i->iov = iov;
i->iov_offset = skip;
return wanted - bytes;
}
static size_t copy_page_from_iter_iovec(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, *to;
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_readable(buf, copy)) {
kaddr = kmap_atomic(page);
to = kaddr + offset;
/* first chunk, usually the only one */
left = __copy_from_user_inatomic(to, buf, copy);
copy -= left;
skip += copy;
to += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __copy_from_user_inatomic(to, buf, copy);
copy -= left;
skip = copy;
to += copy;
bytes -= copy;
}
if (likely(!bytes)) {
kunmap_atomic(kaddr);
goto done;
}
offset = to - kaddr;
buf += copy;
kunmap_atomic(kaddr);
copy = min(bytes, iov->iov_len - skip);
}
/* Too bad - revert to non-atomic kmap */
kaddr = kmap(page);
to = kaddr + offset;
left = __copy_from_user(to, buf, copy);
copy -= left;
skip += copy;
to += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __copy_from_user(to, buf, copy);
copy -= left;
skip = copy;
to += copy;
bytes -= copy;
}
kunmap(page);
done:
if (skip == iov->iov_len) {
iov++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= iov - i->iov;
i->iov = iov;
i->iov_offset = skip;
return wanted - bytes;
}
static size_t zero_iovec(size_t bytes, struct iov_iter *i)
{
size_t skip, copy, left, wanted;
const struct iovec *iov;
char __user *buf;
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);
left = __clear_user(buf, copy);
copy -= left;
skip += copy;
bytes -= copy;
while (unlikely(!left && bytes)) {
iov++;
buf = iov->iov_base;
copy = min(bytes, iov->iov_len);
left = __clear_user(buf, copy);
copy -= left;
skip = copy;
bytes -= copy;
}
if (skip == iov->iov_len) {
iov++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= iov - i->iov;
i->iov = iov;
i->iov_offset = skip;
return wanted - bytes;
}
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.
*/
static size_t copy_from_user_atomic_iovec(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;
}
static void advance_iovec(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;
}
}
/*
* 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)
{
if (!(i->type & ITER_BVEC)) {
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);
}
return 0;
}
EXPORT_SYMBOL(iov_iter_fault_in_readable);
static unsigned long alignment_iovec(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;
}
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 |= ITER_KVEC;
i->type = direction;
i->iov = iov;
i->nr_segs = nr_segs;
i->iov_offset = 0;
i->count = count;
}
EXPORT_SYMBOL(iov_iter_init);
static ssize_t get_pages_iovec(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
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);
if (len > maxpages * PAGE_SIZE)
len = maxpages * PAGE_SIZE;
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;
}
static ssize_t get_pages_alloc_iovec(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;
void *p;
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;
p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
if (!p)
p = vmalloc(n * sizeof(struct page *));
if (!p)
return -ENOMEM;
res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
if (unlikely(res < 0)) {
kvfree(p);
return res;
}
*pages = p;
return (res == n ? len : res * PAGE_SIZE) - *start;
}
static int iov_iter_npages_iovec(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);
}
static void memcpy_from_page(char *to, struct page *page, size_t offset, size_t len)
{
char *from = kmap_atomic(page);
memcpy(to, from + offset, len);
kunmap_atomic(from);
}
static void memcpy_to_page(struct page *page, size_t offset, char *from, size_t len)
{
char *to = kmap_atomic(page);
memcpy(to + offset, from, len);
kunmap_atomic(to);
}
static void memzero_page(struct page *page, size_t offset, size_t len)
{
char *addr = kmap_atomic(page);
memset(addr + offset, 0, len);
kunmap_atomic(addr);
}
static size_t copy_to_iter_bvec(void *from, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, wanted;
const struct bio_vec *bvec;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
bvec = i->bvec;
skip = i->iov_offset;
copy = min_t(size_t, bytes, bvec->bv_len - skip);
memcpy_to_page(bvec->bv_page, skip + bvec->bv_offset, from, copy);
skip += copy;
from += copy;
bytes -= copy;
while (bytes) {
bvec++;
copy = min(bytes, (size_t)bvec->bv_len);
memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, copy);
skip = copy;
from += copy;
bytes -= copy;
}
if (skip == bvec->bv_len) {
bvec++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= bvec - i->bvec;
i->bvec = bvec;
i->iov_offset = skip;
return wanted - bytes;
}
static size_t copy_from_iter_bvec(void *to, size_t bytes, struct iov_iter *i)
{
size_t skip, copy, wanted;
const struct bio_vec *bvec;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
bvec = i->bvec;
skip = i->iov_offset;
copy = min(bytes, bvec->bv_len - skip);
memcpy_from_page(to, bvec->bv_page, bvec->bv_offset + skip, copy);
to += copy;
skip += copy;
bytes -= copy;
while (bytes) {
bvec++;
copy = min(bytes, (size_t)bvec->bv_len);
memcpy_from_page(to, bvec->bv_page, bvec->bv_offset, copy);
skip = copy;
to += copy;
bytes -= copy;
}
if (skip == bvec->bv_len) {
bvec++;
skip = 0;
}
i->count -= wanted;
i->nr_segs -= bvec - i->bvec;
i->bvec = bvec;
i->iov_offset = skip;
return wanted;
}
static size_t copy_page_to_iter_bvec(struct page *page, size_t offset,
size_t bytes, struct iov_iter *i)
{
void *kaddr = kmap_atomic(page);
size_t wanted = copy_to_iter_bvec(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
}
static size_t copy_page_from_iter_bvec(struct page *page, size_t offset,
size_t bytes, struct iov_iter *i)
{
void *kaddr = kmap_atomic(page);
size_t wanted = copy_from_iter_bvec(kaddr + offset, bytes, i);
kunmap_atomic(kaddr);
return wanted;
}
static size_t zero_bvec(size_t bytes, struct iov_iter *i)
{
size_t skip, copy, wanted;
const struct bio_vec *bvec;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
wanted = bytes;
bvec = i->bvec;
skip = i->iov_offset;
copy = min_t(size_t, bytes, bvec->bv_len - skip);
memzero_page(bvec->bv_page, skip + bvec->bv_offset, copy);
skip += copy;
bytes -= copy;
while (bytes) {
bvec++;
copy = min(bytes, (size_t)bvec->bv_len);
memzero_page(bvec->bv_page, bvec->bv_offset, copy);
skip = copy;
bytes -= copy;
}
if (skip == bvec->bv_len) {
bvec++;
skip = 0;
}
i->count -= wanted - bytes;
i->nr_segs -= bvec - i->bvec;
i->bvec = bvec;
i->iov_offset = skip;
return wanted - bytes;
}
static size_t copy_from_user_bvec(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
char *kaddr;
size_t left;
const struct bio_vec *bvec;
size_t base = i->iov_offset;
kaddr = kmap_atomic(page);
for (left = bytes, bvec = i->bvec; left; bvec++, base = 0) {
size_t copy = min(left, bvec->bv_len - base);
if (!bvec->bv_len)
continue;
memcpy_from_page(kaddr + offset, bvec->bv_page,
bvec->bv_offset + base, copy);
offset += copy;
left -= copy;
}
kunmap_atomic(kaddr);
return bytes;
}
static void advance_bvec(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 bio_vec *bvec = i->bvec;
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 && !bvec->bv_len)) {
int copy;
copy = min(bytes, bvec->bv_len - base);
BUG_ON(!i->count || i->count < copy);
i->count -= copy;
bytes -= copy;
base += copy;
if (bvec->bv_len == base) {
bvec++;
nr_segs--;
base = 0;
}
}
i->bvec = bvec;
i->iov_offset = base;
i->nr_segs = nr_segs;
}
}
static unsigned long alignment_bvec(const struct iov_iter *i)
{
const struct bio_vec *bvec = i->bvec;
unsigned long res;
size_t size = i->count;
size_t n;
if (!size)
return 0;
res = bvec->bv_offset + i->iov_offset;
n = bvec->bv_len - i->iov_offset;
if (n >= size)
return res | size;
size -= n;
res |= n;
while (size > (++bvec)->bv_len) {
res |= bvec->bv_offset | bvec->bv_len;
size -= bvec->bv_len;
}
res |= bvec->bv_offset | size;
return res;
}
static ssize_t get_pages_bvec(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
const struct bio_vec *bvec = i->bvec;
size_t len = bvec->bv_len - i->iov_offset;
if (len > i->count)
len = i->count;
if (len > maxsize)
len = maxsize;
/* can't be more than PAGE_SIZE */
*start = bvec->bv_offset + i->iov_offset;
get_page(*pages = bvec->bv_page);
return len;
}
static ssize_t get_pages_alloc_bvec(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
const struct bio_vec *bvec = i->bvec;
size_t len = bvec->bv_len - i->iov_offset;
if (len > i->count)
len = i->count;
if (len > maxsize)
len = maxsize;
*start = bvec->bv_offset + i->iov_offset;
*pages = kmalloc(sizeof(struct page *), GFP_KERNEL);
if (!*pages)
return -ENOMEM;
get_page(**pages = bvec->bv_page);
return len;
}
static int iov_iter_npages_bvec(const struct iov_iter *i, int maxpages)
{
size_t offset = i->iov_offset;
size_t size = i->count;
const struct bio_vec *bvec = i->bvec;
int npages = 0;
int n;
for (n = 0; size && n < i->nr_segs; n++, bvec++) {
size_t len = bvec->bv_len - offset;
offset = 0;
if (unlikely(!len)) /* empty segment */
continue;
if (len > size)
len = size;
npages++;
if (npages >= maxpages) /* don't bother going further */
return maxpages;
size -= len;
offset = 0;
}
return min(npages, maxpages);
}
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
if (i->type & ITER_BVEC)
return copy_page_to_iter_bvec(page, offset, bytes, i);
else
return copy_page_to_iter_iovec(page, offset, bytes, i);
}
EXPORT_SYMBOL(copy_page_to_iter);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
if (i->type & ITER_BVEC)
return copy_page_from_iter_bvec(page, offset, bytes, i);
else
return copy_page_from_iter_iovec(page, offset, bytes, i);
}
EXPORT_SYMBOL(copy_page_from_iter);
size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
{
if (i->type & ITER_BVEC)
return copy_to_iter_bvec(addr, bytes, i);
else
return copy_to_iter_iovec(addr, bytes, i);
}
EXPORT_SYMBOL(copy_to_iter);
size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
{
if (i->type & ITER_BVEC)
return copy_from_iter_bvec(addr, bytes, i);
else
return copy_from_iter_iovec(addr, bytes, i);
}
EXPORT_SYMBOL(copy_from_iter);
size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
{
if (i->type & ITER_BVEC) {
return zero_bvec(bytes, i);
} else {
return zero_iovec(bytes, i);
}
}
EXPORT_SYMBOL(iov_iter_zero);
size_t iov_iter_copy_from_user_atomic(struct page *page,
struct iov_iter *i, unsigned long offset, size_t bytes)
{
if (i->type & ITER_BVEC)
return copy_from_user_bvec(page, i, offset, bytes);
else
return copy_from_user_atomic_iovec(page, i, offset, bytes);
}
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
void iov_iter_advance(struct iov_iter *i, size_t size)
{
if (i->type & ITER_BVEC)
advance_bvec(i, size);
else
advance_iovec(i, size);
}
EXPORT_SYMBOL(iov_iter_advance);
/*
* Return the count of just the current iov_iter segment.
*/
size_t iov_iter_single_seg_count(const struct iov_iter *i)
{
if (i->nr_segs == 1)
return i->count;
else if (i->type & ITER_BVEC)
return min(i->count, i->bvec->bv_len - i->iov_offset);
else
return min(i->count, i->iov->iov_len - i->iov_offset);
}
EXPORT_SYMBOL(iov_iter_single_seg_count);
unsigned long iov_iter_alignment(const struct iov_iter *i)
{
if (i->type & ITER_BVEC)
return alignment_bvec(i);
else
return alignment_iovec(i);
}
EXPORT_SYMBOL(iov_iter_alignment);
ssize_t iov_iter_get_pages(struct iov_iter *i,
struct page **pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
if (i->type & ITER_BVEC)
return get_pages_bvec(i, pages, maxsize, maxpages, start);
else
return get_pages_iovec(i, pages, maxsize, maxpages, start);
}
EXPORT_SYMBOL(iov_iter_get_pages);
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
struct page ***pages, size_t maxsize,
size_t *start)
{
if (i->type & ITER_BVEC)
return get_pages_alloc_bvec(i, pages, maxsize, start);
else
return get_pages_alloc_iovec(i, pages, maxsize, start);
}
EXPORT_SYMBOL(iov_iter_get_pages_alloc);
int iov_iter_npages(const struct iov_iter *i, int maxpages)
{
if (i->type & ITER_BVEC)
return iov_iter_npages_bvec(i, maxpages);
else
return iov_iter_npages_iovec(i, maxpages);
}
EXPORT_SYMBOL(iov_iter_npages);