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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: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Jens Axboe
parent
497f9625c2
commit
1db60cf205
1 changed files with 62 additions and 98 deletions
144
kernel/relay.c
144
kernel/relay.c
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@ -1032,19 +1032,23 @@ static ssize_t relay_file_read(struct file *filp,
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NULL, &desc);
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}
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static void relay_consume_bytes(struct rchan_buf *rbuf, int bytes_consumed)
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{
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rbuf->bytes_consumed += bytes_consumed;
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if (rbuf->bytes_consumed >= rbuf->chan->subbuf_size) {
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relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
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rbuf->bytes_consumed %= rbuf->chan->subbuf_size;
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}
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}
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static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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struct rchan_buf *rbuf;
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rbuf = (struct rchan_buf *)page_private(buf->page);
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rbuf->bytes_consumed += PAGE_SIZE;
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if (rbuf->bytes_consumed == rbuf->chan->subbuf_size) {
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relay_subbufs_consumed(rbuf->chan, rbuf->cpu, 1);
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rbuf->bytes_consumed = 0;
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}
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relay_consume_bytes(rbuf, buf->private);
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}
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static struct pipe_buf_operations relay_pipe_buf_ops = {
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@ -1067,116 +1071,77 @@ static int subbuf_splice_actor(struct file *in,
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unsigned int flags,
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int *nonpad_ret)
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{
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unsigned int pidx, poff;
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unsigned int subbuf_pages;
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int ret = 0;
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int do_wakeup = 0;
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unsigned int pidx, poff, total_len, subbuf_pages, ret;
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struct rchan_buf *rbuf = in->private_data;
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unsigned int subbuf_size = rbuf->chan->subbuf_size;
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size_t read_start = ((size_t)*ppos) % rbuf->chan->alloc_size;
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size_t avail = subbuf_size - read_start % subbuf_size;
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size_t read_subbuf = read_start / subbuf_size;
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size_t padding = rbuf->padding[read_subbuf];
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size_t nonpad_end = read_subbuf * subbuf_size + subbuf_size - padding;
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struct page *pages[PIPE_BUFFERS];
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struct partial_page partial[PIPE_BUFFERS];
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struct splice_pipe_desc spd = {
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.pages = pages,
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.nr_pages = 0,
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.partial = partial,
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.flags = flags,
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.ops = &relay_pipe_buf_ops,
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};
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if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
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return 0;
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if (len > avail)
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len = avail;
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if (pipe->inode)
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mutex_lock(&pipe->inode->i_mutex);
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/*
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* Adjust read len, if longer than what is available
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*/
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if (len > (subbuf_size - read_start % subbuf_size))
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len = subbuf_size - read_start % subbuf_size;
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subbuf_pages = rbuf->chan->alloc_size >> PAGE_SHIFT;
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pidx = (read_start / PAGE_SIZE) % subbuf_pages;
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poff = read_start & ~PAGE_MASK;
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for (;;) {
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unsigned int this_len;
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unsigned int this_end;
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int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1);
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struct pipe_buffer *buf = pipe->bufs + newbuf;
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for (total_len = 0; spd.nr_pages < subbuf_pages; spd.nr_pages++) {
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unsigned int this_len, this_end, private;
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unsigned int cur_pos = read_start + total_len;
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if (!pipe->readers) {
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send_sig(SIGPIPE, current, 0);
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if (!ret)
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ret = -EPIPE;
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if (!len)
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break;
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this_len = min_t(unsigned long, len, PAGE_SIZE - poff);
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private = this_len;
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spd.pages[spd.nr_pages] = rbuf->page_array[pidx];
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spd.partial[spd.nr_pages].offset = poff;
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this_end = cur_pos + this_len;
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if (this_end >= nonpad_end) {
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this_len = nonpad_end - cur_pos;
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private = this_len + padding;
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}
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spd.partial[spd.nr_pages].len = this_len;
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spd.partial[spd.nr_pages].private = private;
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if (pipe->nrbufs < PIPE_BUFFERS) {
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this_len = PAGE_SIZE - poff;
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if (this_len > avail)
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this_len = avail;
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buf->page = rbuf->page_array[pidx];
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buf->offset = poff;
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this_end = read_start + ret + this_len;
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if (this_end > nonpad_end) {
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if (read_start + ret >= nonpad_end)
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buf->len = 0;
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else
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buf->len = nonpad_end - (read_start + ret);
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} else
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buf->len = this_len;
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*nonpad_ret += buf->len;
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buf->ops = &relay_pipe_buf_ops;
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pipe->nrbufs++;
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avail -= this_len;
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ret += this_len;
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len -= this_len;
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total_len += this_len;
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poff = 0;
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pidx = (pidx + 1) % subbuf_pages;
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if (pipe->inode)
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do_wakeup = 1;
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if (!avail)
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break;
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if (pipe->nrbufs < PIPE_BUFFERS)
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continue;
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if (this_end >= nonpad_end) {
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spd.nr_pages++;
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break;
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}
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if (flags & SPLICE_F_NONBLOCK) {
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if (!ret)
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ret = -EAGAIN;
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break;
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}
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if (signal_pending(current)) {
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if (!ret)
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ret = -ERESTARTSYS;
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break;
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}
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if (!spd.nr_pages)
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return 0;
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if (do_wakeup) {
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smp_mb();
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if (waitqueue_active(&pipe->wait))
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wake_up_interruptible_sync(&pipe->wait);
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kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
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do_wakeup = 0;
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}
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ret = *nonpad_ret = splice_to_pipe(pipe, &spd);
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if (ret < 0 || ret < total_len)
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return ret;
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pipe->waiting_writers++;
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pipe_wait(pipe);
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pipe->waiting_writers--;
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}
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if (pipe->inode)
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mutex_unlock(&pipe->inode->i_mutex);
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if (do_wakeup) {
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smp_mb();
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if (waitqueue_active(&pipe->wait))
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wake_up_interruptible(&pipe->wait);
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kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
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}
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if (read_start + ret == nonpad_end)
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ret += padding;
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return ret;
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}
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@ -1199,7 +1164,6 @@ static ssize_t relay_file_splice_read(struct file *in,
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if (ret < 0)
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break;
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else if (!ret) {
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break;
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if (spliced)
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break;
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if (flags & SPLICE_F_NONBLOCK) {
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