Commit 1db60cf2 authored by Jens Axboe's avatar Jens Axboe

relay: use splice_to_pipe() instead of open-coding the pipe loop

It cleans up the relay splice implementation a lot, and gets rid of
a lot of internal pipe knowledge that should not be in there.

Plus fixes for padding and partial first page (and lots more) from
Tom Zanussi.
Signed-off-by: 's avatarJens Axboe <jens.axboe@oracle.com>
parent 497f9625
......@@ -1032,19 +1032,23 @@ static ssize_t relay_file_read(struct file *filp,
NULL, &desc);
}
static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
{
rbuf->bytes_consumed += bytes_consumed;
if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) {
relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
rbuf->bytes_consumed %= rbuf->chan->subbuf_size;
}
}
static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
struct pipe_buffer *buf)
{
struct rchan_buf *rbuf;
rbuf = (struct rchan_buf *)page_private(buf->page);
rbuf->bytes_consumed += PAGE_SIZE;
if (rbuf->bytes_consumed == rbuf->chan->subbuf_size) {
relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
rbuf->bytes_consumed = 0;
}
relay_consume_bytes(rbuf, buf->private);
}
static struct pipe_buf_operations relay_pipe_buf_ops = {
......@@ -1067,118 +1071,79 @@ static int subbuf_splice_actor(struct file *in,
unsigned int flags,
int *nonpad_ret)
{
unsigned int pidx, poff;
unsigned int subbuf_pages;
int ret = 0;
int do_wakeup = 0;
unsigned int pidx, poff, total_len, subbuf_pages, ret;
struct rchan_buf *rbuf = in->private_data;
unsigned int subbuf_size = rbuf->chan->subbuf_size;
size_t read_start = ((size_t)*ppos) % rbuf->chan->alloc_size;
size_t avail = subbuf_size - read_start % subbuf_size;
size_t read_subbuf = read_start / subbuf_size;
size_t padding = rbuf->padding[read_subbuf];
size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
struct page *pages[PIPE_BUFFERS];
struct partial_page partial[PIPE_BUFFERS];
struct splice_pipe_desc spd = {
.pages = pages,
.nr_pages = 0,
.partial = partial,
.flags = flags,
.ops = &relay_pipe_buf_ops,
};
if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
return 0;
if (len > avail)
len = avail;
if (pipe->inode)
mutex_lock(&pipe->inode->i_mutex);
/*
* Adjust read len, if longer than what is available
*/
if (len > (subbuf_size - read_start % subbuf_size))
len = subbuf_size - read_start % subbuf_size;
subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
pidx = (read_start / PAGE_SIZE) % subbuf_pages;
poff = read_start & ~PAGE_MASK;
for (;;) {
unsigned int this_len;
unsigned int this_end;
int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
struct pipe_buffer *buf = pipe->bufs + newbuf;
for (total_len = 0; spd.nr_pages < subbuf_pages; spd.nr_pages++) {
unsigned int this_len, this_end, private;
unsigned int cur_pos = read_start + total_len;
if (!pipe->readers) {
send_sig(SIGPIPE, current, 0);
if (!ret)
ret = -EPIPE;
if (!len)
break;
}
if (pipe->nrbufs < PIPE_BUFFERS) {
this_len = PAGE_SIZE - poff;
if (this_len > avail)
this_len = avail;
buf->page = rbuf->page_array[pidx];
buf->offset = poff;
this_end = read_start + ret + this_len;
if (this_end > nonpad_end) {
if (read_start + ret >= nonpad_end)
buf->len = 0;
else
buf->len = nonpad_end - (read_start + ret);
} else
buf->len = this_len;
*nonpad_ret += buf->len;
buf->ops = &relay_pipe_buf_ops;
pipe->nrbufs++;
avail -= this_len;
ret += this_len;
poff = 0;
pidx = (pidx + 1) % subbuf_pages;
this_len = min_t(unsigned long, len, PAGE_SIZE - poff);
private = this_len;
if (pipe->inode)
do_wakeup = 1;
spd.pages[spd.nr_pages] = rbuf->page_array[pidx];
spd.partial[spd.nr_pages].offset = poff;
if (!avail)
break;
if (pipe->nrbufs < PIPE_BUFFERS)
continue;
break;
this_end = cur_pos + this_len;
if (this_end >= nonpad_end) {
this_len = nonpad_end - cur_pos;
private = this_len + padding;
}
spd.partial[spd.nr_pages].len = this_len;
spd.partial[spd.nr_pages].private = private;
if (flags & SPLICE_F_NONBLOCK) {
if (!ret)
ret = -EAGAIN;
break;
}
len -= this_len;
total_len += this_len;
poff = 0;
pidx = (pidx + 1) % subbuf_pages;
if (signal_pending(current)) {
if (!ret)
ret = -ERESTARTSYS;
if (this_end >= nonpad_end) {
spd.nr_pages++;
break;
}
if (do_wakeup) {
smp_mb();
if (waitqueue_active(&pipe->wait))
wake_up_interruptible_sync(&pipe->wait);
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
do_wakeup = 0;
}
pipe->waiting_writers++;
pipe_wait(pipe);
pipe->waiting_writers--;
}
if (pipe->inode)
mutex_unlock(&pipe->inode->i_mutex);
if (!spd.nr_pages)
return 0;
if (do_wakeup) {
smp_mb();
if (waitqueue_active(&pipe->wait))
wake_up_interruptible(&pipe->wait);
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
}
ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
if (ret < 0 || ret < total_len)
return ret;
return ret;
if (read_start + ret == nonpad_end)
ret += padding;
return ret;
}
static ssize_t relay_file_splice_read(struct file *in,
......@@ -1199,7 +1164,6 @@ static ssize_t relay_file_splice_read(struct file *in,
if (ret < 0)
break;
else if (!ret) {
break;
if (spliced)
break;
if (flags & SPLICE_F_NONBLOCK) {
......
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