splice: relay support

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 191 insertions, 50 deletions

diff --git a/kernel/relay.c b/kernel/relay.c
index 95db8c79fe8..d1d1920f280 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -21,6 +21,7 @@
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
 #include <linux/cpu.h>
+#include <linux/pipe_fs_i.h>
 
 /* list of open channels, for cpu hotplug */
 static DEFINE_MUTEX(relay_channels_mutex);
@@ -121,6 +122,7 @@ static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
                 buf->page_array[i] = alloc_page(GFP_KERNEL);
                 if (unlikely(!buf->page_array[i]))
                         goto depopulate;
+                set_page_private(buf->page_array[i], (unsigned long)buf);
         }
         mem = vmap(buf->page_array, n_pages, VM_MAP, PAGE_KERNEL);
         if (!mem)
@@ -970,43 +972,6 @@ static int subbuf_read_actor(size_t read_start,
         return ret;
 }
 
-/*
- *      subbuf_send_actor - send up to one subbuf's worth of data
- */
-static int subbuf_send_actor(size_t read_start,
-                             struct rchan_buf *buf,
-                             size_t avail,
-                             read_descriptor_t *desc,
-                             read_actor_t actor)
-{
-        unsigned long pidx, poff;
-        unsigned int subbuf_pages;
-        int ret = 0;
-
-        subbuf_pages = buf->chan->alloc_size >> PAGE_SHIFT;
-        pidx = (read_start / PAGE_SIZE) % subbuf_pages;
-        poff = read_start & ~PAGE_MASK;
-        while (avail) {
-                struct page *p = buf->page_array[pidx];
-                unsigned int len;
-
-                len = PAGE_SIZE - poff;
-                if (len > avail)
-                        len = avail;
-
-                len = actor(desc, p, poff, len);
-                if (desc->error)
-                        break;
-
-                avail -= len;
-                ret += len;
-                poff = 0;
-                pidx = (pidx + 1) % subbuf_pages;
-        }
-
-        return ret;
-}
-
 typedef int (*subbuf_actor_t) (size_t read_start,
                                struct rchan_buf *buf,
                                size_t avail,
@@ -1067,19 +1032,195 @@ static ssize_t relay_file_read(struct file *filp,
                                        NULL, &desc);
 }
 
-static ssize_t relay_file_sendfile(struct file *filp,
-                                   loff_t *ppos,
-                                   size_t count,
-                                   read_actor_t actor,
-                                   void *target)
+static void relay_pipe_buf_release(struct pipe_inode_info *pipe,
+                                   struct pipe_buffer *buf)
 {
-        read_descriptor_t desc;
-        desc.written = 0;
-        desc.count = count;
-        desc.arg.data = target;
-        desc.error = 0;
-        return relay_file_read_subbufs(filp, ppos, subbuf_send_actor,
-                                       actor, &desc);
+        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;
+        }
+}
+
+static struct pipe_buf_operations relay_pipe_buf_ops = {
+        .can_merge = 0,
+        .map = generic_pipe_buf_map,
+        .unmap = generic_pipe_buf_unmap,
+        .pin = generic_pipe_buf_pin,
+        .release = relay_pipe_buf_release,
+        .steal = generic_pipe_buf_steal,
+        .get = generic_pipe_buf_get,
+};
+
+/**
+ *      subbuf_splice_actor - splice up to one subbuf's worth of data
+ */
+static int subbuf_splice_actor(struct file *in,
+                               loff_t *ppos,
+                               struct pipe_inode_info *pipe,
+                               size_t len,
+                               unsigned int flags,
+                               int *nonpad_ret)
+{
+        unsigned int pidx, poff;
+        unsigned int subbuf_pages;
+        int ret = 0;
+        int do_wakeup = 0;
+        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;
+
+        if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
+                return 0;
+
+        if (len > avail)
+                len = avail;
+
+        if (pipe->inode)
+                mutex_lock(&pipe->inode->i_mutex);
+
+        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;
+
+                if (!pipe->readers) {
+                        send_sig(SIGPIPE, current, 0);
+                        if (!ret)
+                                ret = -EPIPE;
+                        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;
+
+                        if (pipe->inode)
+                                do_wakeup = 1;
+
+                        if (!avail)
+                                break;
+
+                        if (pipe->nrbufs < PIPE_BUFFERS)
+                                continue;
+
+                        break;
+                }
+
+                if (flags & SPLICE_F_NONBLOCK) {
+                        if (!ret)
+                                ret = -EAGAIN;
+                        break;
+                }
+
+                if (signal_pending(current)) {
+                        if (!ret)
+                                ret = -ERESTARTSYS;
+                        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 (do_wakeup) {
+                smp_mb();
+                if (waitqueue_active(&pipe->wait))
+                        wake_up_interruptible(&pipe->wait);
+                kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+        }
+
+        return ret;
+}
+
+static ssize_t relay_file_splice_read(struct file *in,
+                                      loff_t *ppos,
+                                      struct pipe_inode_info *pipe,
+                                      size_t len,
+                                      unsigned int flags)
+{
+        ssize_t spliced;
+        int ret;
+        int nonpad_ret = 0;
+
+        ret = 0;
+        spliced = 0;
+
+        while (len) {
+                ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret);
+                if (ret < 0)
+                        break;
+                else if (!ret) {
+                        break;
+                        if (spliced)
+                                break;
+                        if (flags & SPLICE_F_NONBLOCK) {
+                                ret = -EAGAIN;
+                                break;
+                        }
+                }
+
+                *ppos += ret;
+                if (ret > len)
+                        len = 0;
+                else
+                        len -= ret;
+                spliced += nonpad_ret;
+                nonpad_ret = 0;
+        }
+
+        if (spliced)
+                return spliced;
+
+        return ret;
 }
 
 const struct file_operations relay_file_operations = {
@@ -1089,7 +1230,7 @@ const struct file_operations relay_file_operations = {
         .read           = relay_file_read,
         .llseek         = no_llseek,
         .release        = relay_file_release,
-        .sendfile       = relay_file_sendfile,
+        .splice_read    = relay_file_splice_read,
 };
 EXPORT_SYMBOL_GPL(relay_file_operations);