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new helper: copy_page_from_iter()
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parallel to copy_page_to_iter().  pipe_write() switched to it (and became
->write_iter()).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Al Viro committed May 6, 2014
1 parent 84c3d55 commit f0d1bec
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Showing 3 changed files with 99 additions and 110 deletions.
129 changes: 19 additions & 110 deletions fs/pipe.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -116,50 +116,6 @@ void pipe_wait(struct pipe_inode_info *pipe)
pipe_lock(pipe);
}

static int
pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
int atomic)
{
unsigned long copy;

while (len > 0) {
while (!iov->iov_len)
iov++;
copy = min_t(unsigned long, len, iov->iov_len);

if (atomic) {
if (__copy_from_user_inatomic(to, iov->iov_base, copy))
return -EFAULT;
} else {
if (copy_from_user(to, iov->iov_base, copy))
return -EFAULT;
}
to += copy;
len -= copy;
iov->iov_base += copy;
iov->iov_len -= copy;
}
return 0;
}

/*
* Pre-fault in the user memory, so we can use atomic copies.
*/
static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len)
{
while (!iov->iov_len)
iov++;

while (len > 0) {
unsigned long this_len;

this_len = min_t(unsigned long, len, iov->iov_len);
fault_in_pages_readable(iov->iov_base, this_len);
len -= this_len;
iov++;
}
}

static void anon_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
Expand Down Expand Up @@ -380,24 +336,19 @@ static inline int is_packetized(struct file *file)
}

static ssize_t
pipe_write(struct kiocb *iocb, const struct iovec *_iov,
unsigned long nr_segs, loff_t ppos)
pipe_write(struct kiocb *iocb, struct iov_iter *from)
{
struct file *filp = iocb->ki_filp;
struct pipe_inode_info *pipe = filp->private_data;
ssize_t ret;
int do_wakeup;
struct iovec *iov = (struct iovec *)_iov;
size_t total_len;
ssize_t ret = 0;
int do_wakeup = 0;
size_t total_len = iov_iter_count(from);
ssize_t chars;

total_len = iov_length(iov, nr_segs);
/* Null write succeeds. */
if (unlikely(total_len == 0))
return 0;

do_wakeup = 0;
ret = 0;
__pipe_lock(pipe);

if (!pipe->readers) {
Expand All @@ -416,38 +367,19 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
int offset = buf->offset + buf->len;

if (ops->can_merge && offset + chars <= PAGE_SIZE) {
int error, atomic = 1;
void *addr;

error = ops->confirm(pipe, buf);
int error = ops->confirm(pipe, buf);
if (error)
goto out;

iov_fault_in_pages_read(iov, chars);
redo1:
if (atomic)
addr = kmap_atomic(buf->page);
else
addr = kmap(buf->page);
error = pipe_iov_copy_from_user(offset + addr, iov,
chars, atomic);
if (atomic)
kunmap_atomic(addr);
else
kunmap(buf->page);
ret = error;
do_wakeup = 1;
if (error) {
if (atomic) {
atomic = 0;
goto redo1;
}
ret = copy_page_from_iter(buf->page, offset, chars, from);
if (unlikely(ret < chars)) {
error = -EFAULT;
goto out;
}
do_wakeup = 1;
buf->len += chars;
total_len -= chars;
ret = chars;
if (!total_len)
if (!iov_iter_count(from))
goto out;
}
}
Expand All @@ -466,8 +398,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1);
struct pipe_buffer *buf = pipe->bufs + newbuf;
struct page *page = pipe->tmp_page;
char *src;
int error, atomic = 1;
int copied;

if (!page) {
page = alloc_page(GFP_HIGHUSER);
Expand All @@ -483,40 +414,19 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
* FIXME! Is this really true?
*/
do_wakeup = 1;
chars = PAGE_SIZE;
if (chars > total_len)
chars = total_len;

iov_fault_in_pages_read(iov, chars);
redo2:
if (atomic)
src = kmap_atomic(page);
else
src = kmap(page);

error = pipe_iov_copy_from_user(src, iov, chars,
atomic);
if (atomic)
kunmap_atomic(src);
else
kunmap(page);

if (unlikely(error)) {
if (atomic) {
atomic = 0;
goto redo2;
}
copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) {
if (!ret)
ret = error;
ret = -EFAULT;
break;
}
ret += chars;
ret += copied;

/* Insert it into the buffer array */
buf->page = page;
buf->ops = &anon_pipe_buf_ops;
buf->offset = 0;
buf->len = chars;
buf->len = copied;
buf->flags = 0;
if (is_packetized(filp)) {
buf->ops = &packet_pipe_buf_ops;
Expand All @@ -525,8 +435,7 @@ pipe_write(struct kiocb *iocb, const struct iovec *_iov,
pipe->nrbufs = ++bufs;
pipe->tmp_page = NULL;

total_len -= chars;
if (!total_len)
if (!iov_iter_count(from))
break;
}
if (bufs < pipe->buffers)
Expand Down Expand Up @@ -1040,8 +949,8 @@ const struct file_operations pipefifo_fops = {
.llseek = no_llseek,
.read = new_sync_read,
.read_iter = pipe_read,
.write = do_sync_write,
.aio_write = pipe_write,
.write = new_sync_write,
.write_iter = pipe_write,
.poll = pipe_poll,
.unlocked_ioctl = pipe_ioctl,
.release = pipe_release,
Expand Down
2 changes: 2 additions & 0 deletions include/linux/uio.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,8 @@ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
size_t iov_iter_single_seg_count(const struct iov_iter *i);
size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i);
unsigned long iov_iter_alignment(const struct iov_iter *i);
void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
unsigned long nr_segs, size_t count);
Expand Down
78 changes: 78 additions & 0 deletions mm/iov_iter.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,84 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
}
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)
{
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:
i->count -= wanted - bytes;
i->nr_segs -= iov - i->iov;
i->iov = iov;
i->iov_offset = skip;
return wanted - bytes;
}
EXPORT_SYMBOL(copy_page_from_iter);

static size_t __iovec_copy_from_user_inatomic(char *vaddr,
const struct iovec *iov, size_t base, size_t bytes)
{
Expand Down

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