From f0d1bec9d58d4c038d0ac958c9af82be6eb18045 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 3 Apr 2014 15:05:18 -0400
Subject: [PATCH] new helper: copy_page_from_iter()
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>
---
fs/pipe.c | 129 +++++++-------------------------------------
include/linux/uio.h | 2 +
mm/iov_iter.c | 78 +++++++++++++++++++++++++++
3 files changed, 99 insertions(+), 110 deletions(-)
diff --git a/fs/pipe.c b/fs/pipe.c
index 05ccb00cb407..21981e58e2a6 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -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)
{
@@ -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) {
@@ -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;
}
}
@@ -466,8 +398,7 @@ redo1:
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);
@@ -483,40 +414,19 @@ redo1:
* 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;
@@ -525,8 +435,7 @@ redo2:
pipe->nrbufs = ++bufs;
pipe->tmp_page = NULL;
- total_len -= chars;
- if (!total_len)
+ if (!iov_iter_count(from))
break;
}
if (bufs < pipe->buffers)
@@ -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,
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 532f59d0adbb..66012352d333 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -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);
diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index a5c691c1a283..081e3273085b 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -82,6 +82,84 @@ done:
}
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)
{