AcoSail/kernel_optimize_test
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switch pipe_read() to copy_page_to_iter()

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2014-02-03 19:11:42 -05:00
parent 74027f4a18
commit 637b58c288
1 changed files with 8 additions and 71 deletions
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79
fs/pipe.c
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@ -142,55 +142,6 @@ pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len,
return 0;
}
static int
pipe_iov_copy_to_user(struct iovec *iov, const void *from, 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_to_user_inatomic(iov->iov_base, from, copy))
return -EFAULT;
} else {
if (copy_to_user(iov->iov_base, from, copy))
return -EFAULT;
}
from += copy;
len -= copy;
iov->iov_base += copy;
iov->iov_len -= copy;
}
return 0;
}
/*
* Attempt to pre-fault in the user memory, so we can use atomic copies.
* Returns the number of bytes not faulted in.
*/
static int iov_fault_in_pages_write(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);
if (fault_in_pages_writeable(iov->iov_base, this_len))
break;
len -= this_len;
iov++;
}
return len;
}
/*
* Pre-fault in the user memory, so we can use atomic copies.
*/
@ -329,12 +280,15 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
ssize_t ret;
struct iovec *iov = (struct iovec *)_iov;
size_t total_len;
struct iov_iter iter;
total_len = iov_length(iov, nr_segs);
/* Null read succeeds. */
if (unlikely(total_len == 0))
return 0;
iov_iter_init(&iter, iov, nr_segs, total_len, 0);
do_wakeup = 0;
ret = 0;
__pipe_lock(pipe);
@ -344,9 +298,9 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
int curbuf = pipe->curbuf;
struct pipe_buffer *buf = pipe->bufs + curbuf;
const struct pipe_buf_operations *ops = buf->ops;
void *addr;
size_t chars = buf->len;
int error, atomic;
size_t written;
int error;
if (chars > total_len)
chars = total_len;
@ -358,27 +312,10 @@ pipe_read(struct kiocb *iocb, const struct iovec *_iov,
break;
}
atomic = !iov_fault_in_pages_write(iov, chars);
redo:
if (atomic)
addr = kmap_atomic(buf->page);
else
addr = kmap(buf->page);
error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic);
if (atomic)
kunmap_atomic(addr);
else
kunmap(buf->page);
if (unlikely(error)) {
/*
* Just retry with the slow path if we failed.
*/
if (atomic) {
atomic = 0;
goto redo;
}
written = copy_page_to_iter(buf->page, buf->offset, chars, &iter);
if (unlikely(written < chars)) {
if (!ret)
ret = error;
ret = -EFAULT;
break;
}
ret += chars;