+++ /dev/null
-/* SPDX-License-Identifier: GPL-2.0-only
- *
- * ring_buffer_splice.c
- *
- * Copyright (C) 2002-2005 - Tom Zanussi <zanussi@us.ibm.com>, IBM Corp
- * Copyright (C) 1999-2005 - Karim Yaghmour <karim@opersys.com>
- * Copyright (C) 2008-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * Re-using code from kernel/relay.c, which is why it is licensed under
- * the GPL-2.0.
- */
-
-#include <linux/module.h>
-#include <linux/fs.h>
-#include <linux/version.h>
-
-#include <wrapper/splice.h>
-#include <ringbuffer/backend.h>
-#include <ringbuffer/frontend.h>
-#include <ringbuffer/vfs.h>
-
-#if 0
-#define printk_dbg(fmt, args...) printk(fmt, args)
-#else
-#define printk_dbg(fmt, args...)
-#endif
-
-loff_t vfs_lib_ring_buffer_no_llseek(struct file *file, loff_t offset,
- int origin)
-{
- return -ESPIPE;
-}
-EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_no_llseek);
-
-/*
- * Release pages from the buffer so splice pipe_to_file can move them.
- * Called after the pipe has been populated with buffer pages.
- */
-static void lib_ring_buffer_pipe_buf_release(struct pipe_inode_info *pipe,
- struct pipe_buffer *pbuf)
-{
- __free_page(pbuf->page);
-}
-
-static const struct pipe_buf_operations ring_buffer_pipe_buf_ops = {
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(5,1,0))
- .can_merge = 0,
-#endif
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(3,15,0))
- .map = generic_pipe_buf_map,
- .unmap = generic_pipe_buf_unmap,
-#endif
- .confirm = generic_pipe_buf_confirm,
- .release = lib_ring_buffer_pipe_buf_release,
- .steal = generic_pipe_buf_steal,
- .get = generic_pipe_buf_get,
-};
-
-/*
- * Page release operation after splice pipe_to_file ends.
- */
-static void lib_ring_buffer_page_release(struct splice_pipe_desc *spd,
- unsigned int i)
-{
- __free_page(spd->pages[i]);
-}
-
-/*
- * 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,
- struct lib_ring_buffer *buf)
-{
- struct channel *chan = buf->backend.chan;
- const struct lib_ring_buffer_config *config = &chan->backend.config;
- unsigned int poff, subbuf_pages, nr_pages;
- struct page *pages[PIPE_DEF_BUFFERS];
- struct partial_page partial[PIPE_DEF_BUFFERS];
- struct splice_pipe_desc spd = {
- .pages = pages,
- .nr_pages = 0,
- .partial = partial,
-#if (LINUX_VERSION_CODE < KERNEL_VERSION(4,12,0))
- .flags = flags,
-#endif
- .ops = &ring_buffer_pipe_buf_ops,
- .spd_release = lib_ring_buffer_page_release,
- };
- unsigned long consumed_old, roffset;
- unsigned long bytes_avail;
-
- /*
- * Check that a GET_SUBBUF ioctl has been done before.
- */
- WARN_ON(atomic_long_read(&buf->active_readers) != 1);
- consumed_old = lib_ring_buffer_get_consumed(config, buf);
- consumed_old += *ppos;
-
- /*
- * Adjust read len, if longer than what is available.
- * Max read size is 1 subbuffer due to get_subbuf/put_subbuf for
- * protection.
- */
- bytes_avail = chan->backend.subbuf_size;
- WARN_ON(bytes_avail > chan->backend.buf_size);
- len = min_t(size_t, len, bytes_avail);
- subbuf_pages = bytes_avail >> PAGE_SHIFT;
- nr_pages = min_t(unsigned int, subbuf_pages, PIPE_DEF_BUFFERS);
- roffset = consumed_old & PAGE_MASK;
- poff = consumed_old & ~PAGE_MASK;
- printk_dbg(KERN_DEBUG "SPLICE actor len %zu pos %zd write_pos %ld\n",
- len, (ssize_t)*ppos, lib_ring_buffer_get_offset(config, buf));
-
- for (; spd.nr_pages < nr_pages; spd.nr_pages++) {
- unsigned int this_len;
- unsigned long *pfnp, new_pfn;
- struct page *new_page;
- void **virt;
-
- if (!len)
- break;
- printk_dbg(KERN_DEBUG "SPLICE actor loop len %zu roffset %ld\n",
- len, roffset);
-
- /*
- * We have to replace the page we are moving into the splice
- * pipe.
- */
- new_page = alloc_pages_node(cpu_to_node(max(buf->backend.cpu,
- 0)),
- GFP_KERNEL | __GFP_ZERO, 0);
- if (!new_page)
- break;
- new_pfn = page_to_pfn(new_page);
- this_len = PAGE_SIZE - poff;
- pfnp = lib_ring_buffer_read_get_pfn(&buf->backend, roffset, &virt);
- spd.pages[spd.nr_pages] = pfn_to_page(*pfnp);
- *pfnp = new_pfn;
- *virt = page_address(new_page);
- spd.partial[spd.nr_pages].offset = poff;
- spd.partial[spd.nr_pages].len = this_len;
-
- poff = 0;
- roffset += PAGE_SIZE;
- len -= this_len;
- }
-
- if (!spd.nr_pages)
- return 0;
-
- return wrapper_splice_to_pipe(pipe, &spd);
-}
-
-ssize_t lib_ring_buffer_splice_read(struct file *in, loff_t *ppos,
- struct pipe_inode_info *pipe, size_t len,
- unsigned int flags,
- struct lib_ring_buffer *buf)
-{
- struct channel *chan = buf->backend.chan;
- const struct lib_ring_buffer_config *config = &chan->backend.config;
- ssize_t spliced;
- int ret;
-
- if (config->output != RING_BUFFER_SPLICE)
- return -EINVAL;
-
- /*
- * We require ppos and length to be page-aligned for performance reasons
- * (no page copy). Size is known using the ioctl
- * RING_BUFFER_GET_PADDED_SUBBUF_SIZE, which is page-size padded.
- * We fail when the ppos or len passed is not page-sized, because splice
- * is not allowed to copy more than the length passed as parameter (so
- * the ABI does not let us silently copy more than requested to include
- * padding).
- */
- if (*ppos != PAGE_ALIGN(*ppos) || len != PAGE_ALIGN(len))
- return -EINVAL;
-
- ret = 0;
- spliced = 0;
-
- printk_dbg(KERN_DEBUG "SPLICE read len %zu pos %zd\n", len,
- (ssize_t)*ppos);
- while (len && !spliced) {
- ret = subbuf_splice_actor(in, ppos, pipe, len, flags, buf);
- printk_dbg(KERN_DEBUG "SPLICE read loop ret %d\n", ret);
- if (ret < 0)
- break;
- else if (!ret) {
- if (flags & SPLICE_F_NONBLOCK)
- ret = -EAGAIN;
- break;
- }
-
- *ppos += ret;
- if (ret > len)
- len = 0;
- else
- len -= ret;
- spliced += ret;
- }
-
- if (spliced)
- return spliced;
-
- return ret;
-}
-EXPORT_SYMBOL_GPL(lib_ring_buffer_splice_read);
-
-ssize_t vfs_lib_ring_buffer_splice_read(struct file *in, loff_t *ppos,
- struct pipe_inode_info *pipe, size_t len,
- unsigned int flags)
-{
- struct lib_ring_buffer *buf = in->private_data;
-
- return lib_ring_buffer_splice_read(in, ppos, pipe, len, flags, buf);
-}
-EXPORT_SYMBOL_GPL(vfs_lib_ring_buffer_splice_read);
projects / lttng-modules.git / blobdiff