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-rw-r--r--fs/pipe.c51
1 files changed, 33 insertions, 18 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index c16950e36ded..ce77ac0d8901 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -387,7 +387,7 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
{
struct file *filp = iocb->ki_filp;
struct pipe_inode_info *pipe = filp->private_data;
- unsigned int head, tail, max_usage, mask;
+ unsigned int head, max_usage, mask;
ssize_t ret = 0;
int do_wakeup = 0;
size_t total_len = iov_iter_count(from);
@@ -405,14 +405,13 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
goto out;
}
- tail = pipe->tail;
head = pipe->head;
max_usage = pipe->max_usage;
mask = pipe->ring_size - 1;
/* We try to merge small writes */
chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */
- if (!pipe_empty(head, tail) && chars != 0) {
+ if (!pipe_empty(head, pipe->tail) && chars != 0) {
struct pipe_buffer *buf = &pipe->bufs[(head - 1) & mask];
int offset = buf->offset + buf->len;
@@ -441,8 +440,8 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
break;
}
- tail = pipe->tail;
- if (!pipe_full(head, tail, max_usage)) {
+ head = pipe->head;
+ if (!pipe_full(head, pipe->tail, max_usage)) {
struct pipe_buffer *buf = &pipe->bufs[head & mask];
struct page *page = pipe->tmp_page;
int copied;
@@ -455,40 +454,56 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
}
pipe->tmp_page = page;
}
+
+ /* Allocate a slot in the ring in advance and attach an
+ * empty buffer. If we fault or otherwise fail to use
+ * it, either the reader will consume it or it'll still
+ * be there for the next write.
+ */
+ spin_lock_irq(&pipe->wait.lock);
+
+ head = pipe->head;
+ pipe->head = head + 1;
+
/* Always wake up, even if the copy fails. Otherwise
* we lock up (O_NONBLOCK-)readers that sleep due to
* syscall merging.
* FIXME! Is this really true?
*/
- do_wakeup = 1;
- copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
- if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) {
- if (!ret)
- ret = -EFAULT;
- break;
- }
- ret += copied;
+ wake_up_interruptible_sync_poll_locked(
+ &pipe->wait, EPOLLIN | EPOLLRDNORM);
+
+ spin_unlock_irq(&pipe->wait.lock);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
/* Insert it into the buffer array */
+ buf = &pipe->bufs[head & mask];
buf->page = page;
buf->ops = &anon_pipe_buf_ops;
buf->offset = 0;
- buf->len = copied;
+ buf->len = 0;
buf->flags = 0;
if (is_packetized(filp)) {
buf->ops = &packet_pipe_buf_ops;
buf->flags = PIPE_BUF_FLAG_PACKET;
}
-
- head++;
- pipe->head = head;
pipe->tmp_page = NULL;
+ copied = copy_page_from_iter(page, 0, PAGE_SIZE, from);
+ if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) {
+ if (!ret)
+ ret = -EFAULT;
+ break;
+ }
+ ret += copied;
+ buf->offset = 0;
+ buf->len = copied;
+
if (!iov_iter_count(from))
break;
}
- if (!pipe_full(head, tail, max_usage))
+ if (!pipe_full(head, pipe->tail, max_usage))
continue;
/* Wait for buffer space to become available. */