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![Al Viro](/assets/img/avatar_default.png)
Backmerge of dcache.c changes from mainline. It's that, or complete rebase... Conflicts: fs/splice.c Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2041 lines
46 KiB
C
2041 lines
46 KiB
C
/*
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* "splice": joining two ropes together by interweaving their strands.
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*
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* This is the "extended pipe" functionality, where a pipe is used as
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* an arbitrary in-memory buffer. Think of a pipe as a small kernel
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* buffer that you can use to transfer data from one end to the other.
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*
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* The traditional unix read/write is extended with a "splice()" operation
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* that transfers data buffers to or from a pipe buffer.
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*
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* Named by Larry McVoy, original implementation from Linus, extended by
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* Jens to support splicing to files, network, direct splicing, etc and
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* fixing lots of bugs.
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*
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* Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
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* Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
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* Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
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*
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*/
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/pagemap.h>
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#include <linux/splice.h>
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#include <linux/memcontrol.h>
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#include <linux/mm_inline.h>
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#include <linux/swap.h>
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#include <linux/writeback.h>
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#include <linux/export.h>
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#include <linux/syscalls.h>
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#include <linux/uio.h>
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#include <linux/security.h>
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#include <linux/gfp.h>
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#include <linux/socket.h>
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#include <linux/compat.h>
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#include <linux/aio.h>
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#include "internal.h"
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/*
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* Attempt to steal a page from a pipe buffer. This should perhaps go into
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* a vm helper function, it's already simplified quite a bit by the
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* addition of remove_mapping(). If success is returned, the caller may
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* attempt to reuse this page for another destination.
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*/
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static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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struct page *page = buf->page;
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struct address_space *mapping;
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lock_page(page);
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mapping = page_mapping(page);
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if (mapping) {
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WARN_ON(!PageUptodate(page));
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/*
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* At least for ext2 with nobh option, we need to wait on
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* writeback completing on this page, since we'll remove it
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* from the pagecache. Otherwise truncate wont wait on the
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* page, allowing the disk blocks to be reused by someone else
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* before we actually wrote our data to them. fs corruption
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* ensues.
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*/
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wait_on_page_writeback(page);
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if (page_has_private(page) &&
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!try_to_release_page(page, GFP_KERNEL))
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goto out_unlock;
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/*
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* If we succeeded in removing the mapping, set LRU flag
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* and return good.
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*/
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if (remove_mapping(mapping, page)) {
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buf->flags |= PIPE_BUF_FLAG_LRU;
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return 0;
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}
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}
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/*
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* Raced with truncate or failed to remove page from current
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* address space, unlock and return failure.
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*/
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out_unlock:
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unlock_page(page);
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return 1;
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}
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static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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page_cache_release(buf->page);
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buf->flags &= ~PIPE_BUF_FLAG_LRU;
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}
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/*
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* Check whether the contents of buf is OK to access. Since the content
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* is a page cache page, IO may be in flight.
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*/
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static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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struct page *page = buf->page;
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int err;
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if (!PageUptodate(page)) {
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lock_page(page);
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/*
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* Page got truncated/unhashed. This will cause a 0-byte
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* splice, if this is the first page.
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*/
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if (!page->mapping) {
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err = -ENODATA;
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goto error;
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}
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/*
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* Uh oh, read-error from disk.
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*/
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if (!PageUptodate(page)) {
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err = -EIO;
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goto error;
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}
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/*
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* Page is ok afterall, we are done.
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*/
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unlock_page(page);
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}
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return 0;
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error:
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unlock_page(page);
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return err;
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}
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const struct pipe_buf_operations page_cache_pipe_buf_ops = {
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.can_merge = 0,
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.confirm = page_cache_pipe_buf_confirm,
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.release = page_cache_pipe_buf_release,
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.steal = page_cache_pipe_buf_steal,
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.get = generic_pipe_buf_get,
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};
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static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
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return 1;
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buf->flags |= PIPE_BUF_FLAG_LRU;
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return generic_pipe_buf_steal(pipe, buf);
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}
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static const struct pipe_buf_operations user_page_pipe_buf_ops = {
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.can_merge = 0,
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.confirm = generic_pipe_buf_confirm,
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.release = page_cache_pipe_buf_release,
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.steal = user_page_pipe_buf_steal,
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.get = generic_pipe_buf_get,
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};
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static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
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{
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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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/**
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* splice_to_pipe - fill passed data into a pipe
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* @pipe: pipe to fill
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* @spd: data to fill
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*
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* Description:
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* @spd contains a map of pages and len/offset tuples, along with
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* the struct pipe_buf_operations associated with these pages. This
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* function will link that data to the pipe.
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*
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*/
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ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
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struct splice_pipe_desc *spd)
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{
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unsigned int spd_pages = spd->nr_pages;
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int ret, do_wakeup, page_nr;
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ret = 0;
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do_wakeup = 0;
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page_nr = 0;
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pipe_lock(pipe);
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for (;;) {
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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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break;
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}
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if (pipe->nrbufs < pipe->buffers) {
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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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buf->page = spd->pages[page_nr];
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buf->offset = spd->partial[page_nr].offset;
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buf->len = spd->partial[page_nr].len;
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buf->private = spd->partial[page_nr].private;
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buf->ops = spd->ops;
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if (spd->flags & SPLICE_F_GIFT)
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buf->flags |= PIPE_BUF_FLAG_GIFT;
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pipe->nrbufs++;
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page_nr++;
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ret += buf->len;
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if (pipe->files)
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do_wakeup = 1;
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if (!--spd->nr_pages)
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break;
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if (pipe->nrbufs < pipe->buffers)
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continue;
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break;
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}
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if (spd->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 (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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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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pipe_unlock(pipe);
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if (do_wakeup)
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wakeup_pipe_readers(pipe);
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while (page_nr < spd_pages)
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spd->spd_release(spd, page_nr++);
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return ret;
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}
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void spd_release_page(struct splice_pipe_desc *spd, unsigned int i)
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{
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page_cache_release(spd->pages[i]);
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}
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/*
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* Check if we need to grow the arrays holding pages and partial page
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* descriptions.
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*/
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int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
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{
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unsigned int buffers = ACCESS_ONCE(pipe->buffers);
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spd->nr_pages_max = buffers;
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if (buffers <= PIPE_DEF_BUFFERS)
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return 0;
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spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
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spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
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if (spd->pages && spd->partial)
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return 0;
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kfree(spd->pages);
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kfree(spd->partial);
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return -ENOMEM;
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}
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void splice_shrink_spd(struct splice_pipe_desc *spd)
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{
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if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
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return;
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kfree(spd->pages);
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kfree(spd->partial);
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}
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static int
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__generic_file_splice_read(struct file *in, loff_t *ppos,
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struct pipe_inode_info *pipe, size_t len,
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unsigned int flags)
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{
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struct address_space *mapping = in->f_mapping;
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unsigned int loff, nr_pages, req_pages;
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struct page *pages[PIPE_DEF_BUFFERS];
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struct partial_page partial[PIPE_DEF_BUFFERS];
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struct page *page;
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pgoff_t index, end_index;
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loff_t isize;
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int error, page_nr;
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struct splice_pipe_desc spd = {
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.pages = pages,
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.partial = partial,
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.nr_pages_max = PIPE_DEF_BUFFERS,
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.flags = flags,
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.ops = &page_cache_pipe_buf_ops,
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.spd_release = spd_release_page,
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};
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if (splice_grow_spd(pipe, &spd))
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return -ENOMEM;
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index = *ppos >> PAGE_CACHE_SHIFT;
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loff = *ppos & ~PAGE_CACHE_MASK;
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req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
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nr_pages = min(req_pages, spd.nr_pages_max);
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/*
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* Lookup the (hopefully) full range of pages we need.
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*/
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spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages);
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index += spd.nr_pages;
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/*
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* If find_get_pages_contig() returned fewer pages than we needed,
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* readahead/allocate the rest and fill in the holes.
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*/
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if (spd.nr_pages < nr_pages)
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page_cache_sync_readahead(mapping, &in->f_ra, in,
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index, req_pages - spd.nr_pages);
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error = 0;
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while (spd.nr_pages < nr_pages) {
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/*
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* Page could be there, find_get_pages_contig() breaks on
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* the first hole.
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*/
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page = find_get_page(mapping, index);
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if (!page) {
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/*
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* page didn't exist, allocate one.
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*/
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page = page_cache_alloc_cold(mapping);
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if (!page)
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break;
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error = add_to_page_cache_lru(page, mapping, index,
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GFP_KERNEL);
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if (unlikely(error)) {
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page_cache_release(page);
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if (error == -EEXIST)
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continue;
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break;
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}
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/*
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* add_to_page_cache() locks the page, unlock it
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* to avoid convoluting the logic below even more.
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*/
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unlock_page(page);
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}
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spd.pages[spd.nr_pages++] = page;
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index++;
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}
|
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|
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/*
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* Now loop over the map and see if we need to start IO on any
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* pages, fill in the partial map, etc.
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*/
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index = *ppos >> PAGE_CACHE_SHIFT;
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nr_pages = spd.nr_pages;
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spd.nr_pages = 0;
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for (page_nr = 0; page_nr < nr_pages; page_nr++) {
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unsigned int this_len;
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if (!len)
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break;
|
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/*
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* this_len is the max we'll use from this page
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*/
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this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
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page = spd.pages[page_nr];
|
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|
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if (PageReadahead(page))
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page_cache_async_readahead(mapping, &in->f_ra, in,
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page, index, req_pages - page_nr);
|
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|
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/*
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* If the page isn't uptodate, we may need to start io on it
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*/
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if (!PageUptodate(page)) {
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lock_page(page);
|
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|
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/*
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* Page was truncated, or invalidated by the
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* filesystem. Redo the find/create, but this time the
|
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* page is kept locked, so there's no chance of another
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* race with truncate/invalidate.
|
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*/
|
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if (!page->mapping) {
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unlock_page(page);
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page = find_or_create_page(mapping, index,
|
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mapping_gfp_mask(mapping));
|
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|
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if (!page) {
|
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error = -ENOMEM;
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break;
|
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}
|
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page_cache_release(spd.pages[page_nr]);
|
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spd.pages[page_nr] = page;
|
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}
|
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/*
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* page was already under io and is now done, great
|
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*/
|
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if (PageUptodate(page)) {
|
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unlock_page(page);
|
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goto fill_it;
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}
|
|
|
|
/*
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* need to read in the page
|
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*/
|
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error = mapping->a_ops->readpage(in, page);
|
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if (unlikely(error)) {
|
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/*
|
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* We really should re-lookup the page here,
|
|
* but it complicates things a lot. Instead
|
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* lets just do what we already stored, and
|
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* we'll get it the next time we are called.
|
|
*/
|
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if (error == AOP_TRUNCATED_PAGE)
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error = 0;
|
|
|
|
break;
|
|
}
|
|
}
|
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fill_it:
|
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/*
|
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* i_size must be checked after PageUptodate.
|
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*/
|
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isize = i_size_read(mapping->host);
|
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end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
|
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if (unlikely(!isize || index > end_index))
|
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break;
|
|
|
|
/*
|
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* if this is the last page, see if we need to shrink
|
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* the length and stop
|
|
*/
|
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if (end_index == index) {
|
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unsigned int plen;
|
|
|
|
/*
|
|
* max good bytes in this page
|
|
*/
|
|
plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
|
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if (plen <= loff)
|
|
break;
|
|
|
|
/*
|
|
* force quit after adding this page
|
|
*/
|
|
this_len = min(this_len, plen - loff);
|
|
len = this_len;
|
|
}
|
|
|
|
spd.partial[page_nr].offset = loff;
|
|
spd.partial[page_nr].len = this_len;
|
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len -= this_len;
|
|
loff = 0;
|
|
spd.nr_pages++;
|
|
index++;
|
|
}
|
|
|
|
/*
|
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* Release any pages at the end, if we quit early. 'page_nr' is how far
|
|
* we got, 'nr_pages' is how many pages are in the map.
|
|
*/
|
|
while (page_nr < nr_pages)
|
|
page_cache_release(spd.pages[page_nr++]);
|
|
in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
|
|
|
|
if (spd.nr_pages)
|
|
error = splice_to_pipe(pipe, &spd);
|
|
|
|
splice_shrink_spd(&spd);
|
|
return error;
|
|
}
|
|
|
|
/**
|
|
* generic_file_splice_read - splice data from file to a pipe
|
|
* @in: file to splice from
|
|
* @ppos: position in @in
|
|
* @pipe: pipe to splice to
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* Will read pages from given file and fill them into a pipe. Can be
|
|
* used as long as the address_space operations for the source implements
|
|
* a readpage() hook.
|
|
*
|
|
*/
|
|
ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
|
|
struct pipe_inode_info *pipe, size_t len,
|
|
unsigned int flags)
|
|
{
|
|
loff_t isize, left;
|
|
int ret;
|
|
|
|
isize = i_size_read(in->f_mapping->host);
|
|
if (unlikely(*ppos >= isize))
|
|
return 0;
|
|
|
|
left = isize - *ppos;
|
|
if (unlikely(left < len))
|
|
len = left;
|
|
|
|
ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
|
|
if (ret > 0) {
|
|
*ppos += ret;
|
|
file_accessed(in);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(generic_file_splice_read);
|
|
|
|
static const struct pipe_buf_operations default_pipe_buf_ops = {
|
|
.can_merge = 0,
|
|
.confirm = generic_pipe_buf_confirm,
|
|
.release = generic_pipe_buf_release,
|
|
.steal = generic_pipe_buf_steal,
|
|
.get = generic_pipe_buf_get,
|
|
};
|
|
|
|
static int generic_pipe_buf_nosteal(struct pipe_inode_info *pipe,
|
|
struct pipe_buffer *buf)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
/* Pipe buffer operations for a socket and similar. */
|
|
const struct pipe_buf_operations nosteal_pipe_buf_ops = {
|
|
.can_merge = 0,
|
|
.confirm = generic_pipe_buf_confirm,
|
|
.release = generic_pipe_buf_release,
|
|
.steal = generic_pipe_buf_nosteal,
|
|
.get = generic_pipe_buf_get,
|
|
};
|
|
EXPORT_SYMBOL(nosteal_pipe_buf_ops);
|
|
|
|
static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
|
|
unsigned long vlen, loff_t offset)
|
|
{
|
|
mm_segment_t old_fs;
|
|
loff_t pos = offset;
|
|
ssize_t res;
|
|
|
|
old_fs = get_fs();
|
|
set_fs(get_ds());
|
|
/* The cast to a user pointer is valid due to the set_fs() */
|
|
res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos);
|
|
set_fs(old_fs);
|
|
|
|
return res;
|
|
}
|
|
|
|
ssize_t kernel_write(struct file *file, const char *buf, size_t count,
|
|
loff_t pos)
|
|
{
|
|
mm_segment_t old_fs;
|
|
ssize_t res;
|
|
|
|
old_fs = get_fs();
|
|
set_fs(get_ds());
|
|
/* The cast to a user pointer is valid due to the set_fs() */
|
|
res = vfs_write(file, (__force const char __user *)buf, count, &pos);
|
|
set_fs(old_fs);
|
|
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(kernel_write);
|
|
|
|
ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
|
|
struct pipe_inode_info *pipe, size_t len,
|
|
unsigned int flags)
|
|
{
|
|
unsigned int nr_pages;
|
|
unsigned int nr_freed;
|
|
size_t offset;
|
|
struct page *pages[PIPE_DEF_BUFFERS];
|
|
struct partial_page partial[PIPE_DEF_BUFFERS];
|
|
struct iovec *vec, __vec[PIPE_DEF_BUFFERS];
|
|
ssize_t res;
|
|
size_t this_len;
|
|
int error;
|
|
int i;
|
|
struct splice_pipe_desc spd = {
|
|
.pages = pages,
|
|
.partial = partial,
|
|
.nr_pages_max = PIPE_DEF_BUFFERS,
|
|
.flags = flags,
|
|
.ops = &default_pipe_buf_ops,
|
|
.spd_release = spd_release_page,
|
|
};
|
|
|
|
if (splice_grow_spd(pipe, &spd))
|
|
return -ENOMEM;
|
|
|
|
res = -ENOMEM;
|
|
vec = __vec;
|
|
if (spd.nr_pages_max > PIPE_DEF_BUFFERS) {
|
|
vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL);
|
|
if (!vec)
|
|
goto shrink_ret;
|
|
}
|
|
|
|
offset = *ppos & ~PAGE_CACHE_MASK;
|
|
nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
|
|
|
for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) {
|
|
struct page *page;
|
|
|
|
page = alloc_page(GFP_USER);
|
|
error = -ENOMEM;
|
|
if (!page)
|
|
goto err;
|
|
|
|
this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset);
|
|
vec[i].iov_base = (void __user *) page_address(page);
|
|
vec[i].iov_len = this_len;
|
|
spd.pages[i] = page;
|
|
spd.nr_pages++;
|
|
len -= this_len;
|
|
offset = 0;
|
|
}
|
|
|
|
res = kernel_readv(in, vec, spd.nr_pages, *ppos);
|
|
if (res < 0) {
|
|
error = res;
|
|
goto err;
|
|
}
|
|
|
|
error = 0;
|
|
if (!res)
|
|
goto err;
|
|
|
|
nr_freed = 0;
|
|
for (i = 0; i < spd.nr_pages; i++) {
|
|
this_len = min_t(size_t, vec[i].iov_len, res);
|
|
spd.partial[i].offset = 0;
|
|
spd.partial[i].len = this_len;
|
|
if (!this_len) {
|
|
__free_page(spd.pages[i]);
|
|
spd.pages[i] = NULL;
|
|
nr_freed++;
|
|
}
|
|
res -= this_len;
|
|
}
|
|
spd.nr_pages -= nr_freed;
|
|
|
|
res = splice_to_pipe(pipe, &spd);
|
|
if (res > 0)
|
|
*ppos += res;
|
|
|
|
shrink_ret:
|
|
if (vec != __vec)
|
|
kfree(vec);
|
|
splice_shrink_spd(&spd);
|
|
return res;
|
|
|
|
err:
|
|
for (i = 0; i < spd.nr_pages; i++)
|
|
__free_page(spd.pages[i]);
|
|
|
|
res = error;
|
|
goto shrink_ret;
|
|
}
|
|
EXPORT_SYMBOL(default_file_splice_read);
|
|
|
|
/*
|
|
* Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
|
|
* using sendpage(). Return the number of bytes sent.
|
|
*/
|
|
static int pipe_to_sendpage(struct pipe_inode_info *pipe,
|
|
struct pipe_buffer *buf, struct splice_desc *sd)
|
|
{
|
|
struct file *file = sd->u.file;
|
|
loff_t pos = sd->pos;
|
|
int more;
|
|
|
|
if (!likely(file->f_op->sendpage))
|
|
return -EINVAL;
|
|
|
|
more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
|
|
|
|
if (sd->len < sd->total_len && pipe->nrbufs > 1)
|
|
more |= MSG_SENDPAGE_NOTLAST;
|
|
|
|
return file->f_op->sendpage(file, buf->page, buf->offset,
|
|
sd->len, &pos, more);
|
|
}
|
|
|
|
static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
|
|
{
|
|
smp_mb();
|
|
if (waitqueue_active(&pipe->wait))
|
|
wake_up_interruptible(&pipe->wait);
|
|
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
|
|
}
|
|
|
|
/**
|
|
* splice_from_pipe_feed - feed available data from a pipe to a file
|
|
* @pipe: pipe to splice from
|
|
* @sd: information to @actor
|
|
* @actor: handler that splices the data
|
|
*
|
|
* Description:
|
|
* This function loops over the pipe and calls @actor to do the
|
|
* actual moving of a single struct pipe_buffer to the desired
|
|
* destination. It returns when there's no more buffers left in
|
|
* the pipe or if the requested number of bytes (@sd->total_len)
|
|
* have been copied. It returns a positive number (one) if the
|
|
* pipe needs to be filled with more data, zero if the required
|
|
* number of bytes have been copied and -errno on error.
|
|
*
|
|
* This, together with splice_from_pipe_{begin,end,next}, may be
|
|
* used to implement the functionality of __splice_from_pipe() when
|
|
* locking is required around copying the pipe buffers to the
|
|
* destination.
|
|
*/
|
|
static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
|
|
splice_actor *actor)
|
|
{
|
|
int ret;
|
|
|
|
while (pipe->nrbufs) {
|
|
struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
|
|
const struct pipe_buf_operations *ops = buf->ops;
|
|
|
|
sd->len = buf->len;
|
|
if (sd->len > sd->total_len)
|
|
sd->len = sd->total_len;
|
|
|
|
ret = buf->ops->confirm(pipe, buf);
|
|
if (unlikely(ret)) {
|
|
if (ret == -ENODATA)
|
|
ret = 0;
|
|
return ret;
|
|
}
|
|
|
|
ret = actor(pipe, buf, sd);
|
|
if (ret <= 0)
|
|
return ret;
|
|
|
|
buf->offset += ret;
|
|
buf->len -= ret;
|
|
|
|
sd->num_spliced += ret;
|
|
sd->len -= ret;
|
|
sd->pos += ret;
|
|
sd->total_len -= ret;
|
|
|
|
if (!buf->len) {
|
|
buf->ops = NULL;
|
|
ops->release(pipe, buf);
|
|
pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
|
|
pipe->nrbufs--;
|
|
if (pipe->files)
|
|
sd->need_wakeup = true;
|
|
}
|
|
|
|
if (!sd->total_len)
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* splice_from_pipe_next - wait for some data to splice from
|
|
* @pipe: pipe to splice from
|
|
* @sd: information about the splice operation
|
|
*
|
|
* Description:
|
|
* This function will wait for some data and return a positive
|
|
* value (one) if pipe buffers are available. It will return zero
|
|
* or -errno if no more data needs to be spliced.
|
|
*/
|
|
static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
|
|
{
|
|
while (!pipe->nrbufs) {
|
|
if (!pipe->writers)
|
|
return 0;
|
|
|
|
if (!pipe->waiting_writers && sd->num_spliced)
|
|
return 0;
|
|
|
|
if (sd->flags & SPLICE_F_NONBLOCK)
|
|
return -EAGAIN;
|
|
|
|
if (signal_pending(current))
|
|
return -ERESTARTSYS;
|
|
|
|
if (sd->need_wakeup) {
|
|
wakeup_pipe_writers(pipe);
|
|
sd->need_wakeup = false;
|
|
}
|
|
|
|
pipe_wait(pipe);
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* splice_from_pipe_begin - start splicing from pipe
|
|
* @sd: information about the splice operation
|
|
*
|
|
* Description:
|
|
* This function should be called before a loop containing
|
|
* splice_from_pipe_next() and splice_from_pipe_feed() to
|
|
* initialize the necessary fields of @sd.
|
|
*/
|
|
static void splice_from_pipe_begin(struct splice_desc *sd)
|
|
{
|
|
sd->num_spliced = 0;
|
|
sd->need_wakeup = false;
|
|
}
|
|
|
|
/**
|
|
* splice_from_pipe_end - finish splicing from pipe
|
|
* @pipe: pipe to splice from
|
|
* @sd: information about the splice operation
|
|
*
|
|
* Description:
|
|
* This function will wake up pipe writers if necessary. It should
|
|
* be called after a loop containing splice_from_pipe_next() and
|
|
* splice_from_pipe_feed().
|
|
*/
|
|
static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
|
|
{
|
|
if (sd->need_wakeup)
|
|
wakeup_pipe_writers(pipe);
|
|
}
|
|
|
|
/**
|
|
* __splice_from_pipe - splice data from a pipe to given actor
|
|
* @pipe: pipe to splice from
|
|
* @sd: information to @actor
|
|
* @actor: handler that splices the data
|
|
*
|
|
* Description:
|
|
* This function does little more than loop over the pipe and call
|
|
* @actor to do the actual moving of a single struct pipe_buffer to
|
|
* the desired destination. See pipe_to_file, pipe_to_sendpage, or
|
|
* pipe_to_user.
|
|
*
|
|
*/
|
|
ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
|
|
splice_actor *actor)
|
|
{
|
|
int ret;
|
|
|
|
splice_from_pipe_begin(sd);
|
|
do {
|
|
ret = splice_from_pipe_next(pipe, sd);
|
|
if (ret > 0)
|
|
ret = splice_from_pipe_feed(pipe, sd, actor);
|
|
} while (ret > 0);
|
|
splice_from_pipe_end(pipe, sd);
|
|
|
|
return sd->num_spliced ? sd->num_spliced : ret;
|
|
}
|
|
EXPORT_SYMBOL(__splice_from_pipe);
|
|
|
|
/**
|
|
* splice_from_pipe - splice data from a pipe to a file
|
|
* @pipe: pipe to splice from
|
|
* @out: file to splice to
|
|
* @ppos: position in @out
|
|
* @len: how many bytes to splice
|
|
* @flags: splice modifier flags
|
|
* @actor: handler that splices the data
|
|
*
|
|
* Description:
|
|
* See __splice_from_pipe. This function locks the pipe inode,
|
|
* otherwise it's identical to __splice_from_pipe().
|
|
*
|
|
*/
|
|
ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags,
|
|
splice_actor *actor)
|
|
{
|
|
ssize_t ret;
|
|
struct splice_desc sd = {
|
|
.total_len = len,
|
|
.flags = flags,
|
|
.pos = *ppos,
|
|
.u.file = out,
|
|
};
|
|
|
|
pipe_lock(pipe);
|
|
ret = __splice_from_pipe(pipe, &sd, actor);
|
|
pipe_unlock(pipe);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* iter_file_splice_write - splice data from a pipe to a file
|
|
* @pipe: pipe info
|
|
* @out: file to write to
|
|
* @ppos: position in @out
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* Will either move or copy pages (determined by @flags options) from
|
|
* the given pipe inode to the given file.
|
|
* This one is ->write_iter-based.
|
|
*
|
|
*/
|
|
ssize_t
|
|
iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
struct splice_desc sd = {
|
|
.total_len = len,
|
|
.flags = flags,
|
|
.pos = *ppos,
|
|
.u.file = out,
|
|
};
|
|
int nbufs = pipe->buffers;
|
|
struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
|
|
GFP_KERNEL);
|
|
ssize_t ret;
|
|
|
|
if (unlikely(!array))
|
|
return -ENOMEM;
|
|
|
|
pipe_lock(pipe);
|
|
|
|
splice_from_pipe_begin(&sd);
|
|
while (sd.total_len) {
|
|
struct iov_iter from;
|
|
struct kiocb kiocb;
|
|
size_t left;
|
|
int n, idx;
|
|
|
|
ret = splice_from_pipe_next(pipe, &sd);
|
|
if (ret <= 0)
|
|
break;
|
|
|
|
if (unlikely(nbufs < pipe->buffers)) {
|
|
kfree(array);
|
|
nbufs = pipe->buffers;
|
|
array = kcalloc(nbufs, sizeof(struct bio_vec),
|
|
GFP_KERNEL);
|
|
if (!array) {
|
|
ret = -ENOMEM;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* build the vector */
|
|
left = sd.total_len;
|
|
for (n = 0, idx = pipe->curbuf; left && n < pipe->nrbufs; n++, idx++) {
|
|
struct pipe_buffer *buf = pipe->bufs + idx;
|
|
size_t this_len = buf->len;
|
|
|
|
if (this_len > left)
|
|
this_len = left;
|
|
|
|
if (idx == pipe->buffers - 1)
|
|
idx = -1;
|
|
|
|
ret = buf->ops->confirm(pipe, buf);
|
|
if (unlikely(ret)) {
|
|
if (ret == -ENODATA)
|
|
ret = 0;
|
|
goto done;
|
|
}
|
|
|
|
array[n].bv_page = buf->page;
|
|
array[n].bv_len = this_len;
|
|
array[n].bv_offset = buf->offset;
|
|
left -= this_len;
|
|
}
|
|
|
|
/* ... iov_iter */
|
|
from.type = ITER_BVEC | WRITE;
|
|
from.bvec = array;
|
|
from.nr_segs = n;
|
|
from.count = sd.total_len - left;
|
|
from.iov_offset = 0;
|
|
|
|
/* ... and iocb */
|
|
init_sync_kiocb(&kiocb, out);
|
|
kiocb.ki_pos = sd.pos;
|
|
kiocb.ki_nbytes = sd.total_len - left;
|
|
|
|
/* now, send it */
|
|
ret = out->f_op->write_iter(&kiocb, &from);
|
|
if (-EIOCBQUEUED == ret)
|
|
ret = wait_on_sync_kiocb(&kiocb);
|
|
|
|
if (ret <= 0)
|
|
break;
|
|
|
|
sd.num_spliced += ret;
|
|
sd.total_len -= ret;
|
|
*ppos = sd.pos = kiocb.ki_pos;
|
|
|
|
/* dismiss the fully eaten buffers, adjust the partial one */
|
|
while (ret) {
|
|
struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
|
|
if (ret >= buf->len) {
|
|
const struct pipe_buf_operations *ops = buf->ops;
|
|
ret -= buf->len;
|
|
buf->len = 0;
|
|
buf->ops = NULL;
|
|
ops->release(pipe, buf);
|
|
pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
|
|
pipe->nrbufs--;
|
|
if (pipe->files)
|
|
sd.need_wakeup = true;
|
|
} else {
|
|
buf->offset += ret;
|
|
buf->len -= ret;
|
|
ret = 0;
|
|
}
|
|
}
|
|
}
|
|
done:
|
|
kfree(array);
|
|
splice_from_pipe_end(pipe, &sd);
|
|
|
|
pipe_unlock(pipe);
|
|
|
|
if (sd.num_spliced)
|
|
ret = sd.num_spliced;
|
|
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(iter_file_splice_write);
|
|
|
|
static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
|
|
struct splice_desc *sd)
|
|
{
|
|
int ret;
|
|
void *data;
|
|
loff_t tmp = sd->pos;
|
|
|
|
data = kmap(buf->page);
|
|
ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);
|
|
kunmap(buf->page);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
|
|
struct file *out, loff_t *ppos,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
ssize_t ret;
|
|
|
|
ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
|
|
if (ret > 0)
|
|
*ppos += ret;
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* generic_splice_sendpage - splice data from a pipe to a socket
|
|
* @pipe: pipe to splice from
|
|
* @out: socket to write to
|
|
* @ppos: position in @out
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* Will send @len bytes from the pipe to a network socket. No data copying
|
|
* is involved.
|
|
*
|
|
*/
|
|
ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_splice_sendpage);
|
|
|
|
/*
|
|
* Attempt to initiate a splice from pipe to file.
|
|
*/
|
|
static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
|
|
loff_t *, size_t, unsigned int);
|
|
|
|
if (out->f_op->splice_write)
|
|
splice_write = out->f_op->splice_write;
|
|
else
|
|
splice_write = default_file_splice_write;
|
|
|
|
return splice_write(pipe, out, ppos, len, flags);
|
|
}
|
|
|
|
/*
|
|
* Attempt to initiate a splice from a file to a pipe.
|
|
*/
|
|
static long do_splice_to(struct file *in, loff_t *ppos,
|
|
struct pipe_inode_info *pipe, size_t len,
|
|
unsigned int flags)
|
|
{
|
|
ssize_t (*splice_read)(struct file *, loff_t *,
|
|
struct pipe_inode_info *, size_t, unsigned int);
|
|
int ret;
|
|
|
|
if (unlikely(!(in->f_mode & FMODE_READ)))
|
|
return -EBADF;
|
|
|
|
ret = rw_verify_area(READ, in, ppos, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
if (in->f_op->splice_read)
|
|
splice_read = in->f_op->splice_read;
|
|
else
|
|
splice_read = default_file_splice_read;
|
|
|
|
return splice_read(in, ppos, pipe, len, flags);
|
|
}
|
|
|
|
/**
|
|
* splice_direct_to_actor - splices data directly between two non-pipes
|
|
* @in: file to splice from
|
|
* @sd: actor information on where to splice to
|
|
* @actor: handles the data splicing
|
|
*
|
|
* Description:
|
|
* This is a special case helper to splice directly between two
|
|
* points, without requiring an explicit pipe. Internally an allocated
|
|
* pipe is cached in the process, and reused during the lifetime of
|
|
* that process.
|
|
*
|
|
*/
|
|
ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
|
|
splice_direct_actor *actor)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
long ret, bytes;
|
|
umode_t i_mode;
|
|
size_t len;
|
|
int i, flags;
|
|
|
|
/*
|
|
* We require the input being a regular file, as we don't want to
|
|
* randomly drop data for eg socket -> socket splicing. Use the
|
|
* piped splicing for that!
|
|
*/
|
|
i_mode = file_inode(in)->i_mode;
|
|
if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode)))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* neither in nor out is a pipe, setup an internal pipe attached to
|
|
* 'out' and transfer the wanted data from 'in' to 'out' through that
|
|
*/
|
|
pipe = current->splice_pipe;
|
|
if (unlikely(!pipe)) {
|
|
pipe = alloc_pipe_info();
|
|
if (!pipe)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* We don't have an immediate reader, but we'll read the stuff
|
|
* out of the pipe right after the splice_to_pipe(). So set
|
|
* PIPE_READERS appropriately.
|
|
*/
|
|
pipe->readers = 1;
|
|
|
|
current->splice_pipe = pipe;
|
|
}
|
|
|
|
/*
|
|
* Do the splice.
|
|
*/
|
|
ret = 0;
|
|
bytes = 0;
|
|
len = sd->total_len;
|
|
flags = sd->flags;
|
|
|
|
/*
|
|
* Don't block on output, we have to drain the direct pipe.
|
|
*/
|
|
sd->flags &= ~SPLICE_F_NONBLOCK;
|
|
|
|
while (len) {
|
|
size_t read_len;
|
|
loff_t pos = sd->pos, prev_pos = pos;
|
|
|
|
ret = do_splice_to(in, &pos, pipe, len, flags);
|
|
if (unlikely(ret <= 0))
|
|
goto out_release;
|
|
|
|
read_len = ret;
|
|
sd->total_len = read_len;
|
|
|
|
/*
|
|
* NOTE: nonblocking mode only applies to the input. We
|
|
* must not do the output in nonblocking mode as then we
|
|
* could get stuck data in the internal pipe:
|
|
*/
|
|
ret = actor(pipe, sd);
|
|
if (unlikely(ret <= 0)) {
|
|
sd->pos = prev_pos;
|
|
goto out_release;
|
|
}
|
|
|
|
bytes += ret;
|
|
len -= ret;
|
|
sd->pos = pos;
|
|
|
|
if (ret < read_len) {
|
|
sd->pos = prev_pos + ret;
|
|
goto out_release;
|
|
}
|
|
}
|
|
|
|
done:
|
|
pipe->nrbufs = pipe->curbuf = 0;
|
|
file_accessed(in);
|
|
return bytes;
|
|
|
|
out_release:
|
|
/*
|
|
* If we did an incomplete transfer we must release
|
|
* the pipe buffers in question:
|
|
*/
|
|
for (i = 0; i < pipe->buffers; i++) {
|
|
struct pipe_buffer *buf = pipe->bufs + i;
|
|
|
|
if (buf->ops) {
|
|
buf->ops->release(pipe, buf);
|
|
buf->ops = NULL;
|
|
}
|
|
}
|
|
|
|
if (!bytes)
|
|
bytes = ret;
|
|
|
|
goto done;
|
|
}
|
|
EXPORT_SYMBOL(splice_direct_to_actor);
|
|
|
|
static int direct_splice_actor(struct pipe_inode_info *pipe,
|
|
struct splice_desc *sd)
|
|
{
|
|
struct file *file = sd->u.file;
|
|
|
|
return do_splice_from(pipe, file, sd->opos, sd->total_len,
|
|
sd->flags);
|
|
}
|
|
|
|
/**
|
|
* do_splice_direct - splices data directly between two files
|
|
* @in: file to splice from
|
|
* @ppos: input file offset
|
|
* @out: file to splice to
|
|
* @opos: output file offset
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Description:
|
|
* For use by do_sendfile(). splice can easily emulate sendfile, but
|
|
* doing it in the application would incur an extra system call
|
|
* (splice in + splice out, as compared to just sendfile()). So this helper
|
|
* can splice directly through a process-private pipe.
|
|
*
|
|
*/
|
|
long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
|
|
loff_t *opos, size_t len, unsigned int flags)
|
|
{
|
|
struct splice_desc sd = {
|
|
.len = len,
|
|
.total_len = len,
|
|
.flags = flags,
|
|
.pos = *ppos,
|
|
.u.file = out,
|
|
.opos = opos,
|
|
};
|
|
long ret;
|
|
|
|
if (unlikely(!(out->f_mode & FMODE_WRITE)))
|
|
return -EBADF;
|
|
|
|
if (unlikely(out->f_flags & O_APPEND))
|
|
return -EINVAL;
|
|
|
|
ret = rw_verify_area(WRITE, out, opos, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
|
|
if (ret > 0)
|
|
*ppos = sd.pos;
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
|
|
struct pipe_inode_info *opipe,
|
|
size_t len, unsigned int flags);
|
|
|
|
/*
|
|
* Determine where to splice to/from.
|
|
*/
|
|
static long do_splice(struct file *in, loff_t __user *off_in,
|
|
struct file *out, loff_t __user *off_out,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *ipipe;
|
|
struct pipe_inode_info *opipe;
|
|
loff_t offset;
|
|
long ret;
|
|
|
|
ipipe = get_pipe_info(in);
|
|
opipe = get_pipe_info(out);
|
|
|
|
if (ipipe && opipe) {
|
|
if (off_in || off_out)
|
|
return -ESPIPE;
|
|
|
|
if (!(in->f_mode & FMODE_READ))
|
|
return -EBADF;
|
|
|
|
if (!(out->f_mode & FMODE_WRITE))
|
|
return -EBADF;
|
|
|
|
/* Splicing to self would be fun, but... */
|
|
if (ipipe == opipe)
|
|
return -EINVAL;
|
|
|
|
return splice_pipe_to_pipe(ipipe, opipe, len, flags);
|
|
}
|
|
|
|
if (ipipe) {
|
|
if (off_in)
|
|
return -ESPIPE;
|
|
if (off_out) {
|
|
if (!(out->f_mode & FMODE_PWRITE))
|
|
return -EINVAL;
|
|
if (copy_from_user(&offset, off_out, sizeof(loff_t)))
|
|
return -EFAULT;
|
|
} else {
|
|
offset = out->f_pos;
|
|
}
|
|
|
|
if (unlikely(!(out->f_mode & FMODE_WRITE)))
|
|
return -EBADF;
|
|
|
|
if (unlikely(out->f_flags & O_APPEND))
|
|
return -EINVAL;
|
|
|
|
ret = rw_verify_area(WRITE, out, &offset, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
file_start_write(out);
|
|
ret = do_splice_from(ipipe, out, &offset, len, flags);
|
|
file_end_write(out);
|
|
|
|
if (!off_out)
|
|
out->f_pos = offset;
|
|
else if (copy_to_user(off_out, &offset, sizeof(loff_t)))
|
|
ret = -EFAULT;
|
|
|
|
return ret;
|
|
}
|
|
|
|
if (opipe) {
|
|
if (off_out)
|
|
return -ESPIPE;
|
|
if (off_in) {
|
|
if (!(in->f_mode & FMODE_PREAD))
|
|
return -EINVAL;
|
|
if (copy_from_user(&offset, off_in, sizeof(loff_t)))
|
|
return -EFAULT;
|
|
} else {
|
|
offset = in->f_pos;
|
|
}
|
|
|
|
ret = do_splice_to(in, &offset, opipe, len, flags);
|
|
|
|
if (!off_in)
|
|
in->f_pos = offset;
|
|
else if (copy_to_user(off_in, &offset, sizeof(loff_t)))
|
|
ret = -EFAULT;
|
|
|
|
return ret;
|
|
}
|
|
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* Map an iov into an array of pages and offset/length tupples. With the
|
|
* partial_page structure, we can map several non-contiguous ranges into
|
|
* our ones pages[] map instead of splitting that operation into pieces.
|
|
* Could easily be exported as a generic helper for other users, in which
|
|
* case one would probably want to add a 'max_nr_pages' parameter as well.
|
|
*/
|
|
static int get_iovec_page_array(const struct iovec __user *iov,
|
|
unsigned int nr_vecs, struct page **pages,
|
|
struct partial_page *partial, bool aligned,
|
|
unsigned int pipe_buffers)
|
|
{
|
|
int buffers = 0, error = 0;
|
|
|
|
while (nr_vecs) {
|
|
unsigned long off, npages;
|
|
struct iovec entry;
|
|
void __user *base;
|
|
size_t len;
|
|
int i;
|
|
|
|
error = -EFAULT;
|
|
if (copy_from_user(&entry, iov, sizeof(entry)))
|
|
break;
|
|
|
|
base = entry.iov_base;
|
|
len = entry.iov_len;
|
|
|
|
/*
|
|
* Sanity check this iovec. 0 read succeeds.
|
|
*/
|
|
error = 0;
|
|
if (unlikely(!len))
|
|
break;
|
|
error = -EFAULT;
|
|
if (!access_ok(VERIFY_READ, base, len))
|
|
break;
|
|
|
|
/*
|
|
* Get this base offset and number of pages, then map
|
|
* in the user pages.
|
|
*/
|
|
off = (unsigned long) base & ~PAGE_MASK;
|
|
|
|
/*
|
|
* If asked for alignment, the offset must be zero and the
|
|
* length a multiple of the PAGE_SIZE.
|
|
*/
|
|
error = -EINVAL;
|
|
if (aligned && (off || len & ~PAGE_MASK))
|
|
break;
|
|
|
|
npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
if (npages > pipe_buffers - buffers)
|
|
npages = pipe_buffers - buffers;
|
|
|
|
error = get_user_pages_fast((unsigned long)base, npages,
|
|
0, &pages[buffers]);
|
|
|
|
if (unlikely(error <= 0))
|
|
break;
|
|
|
|
/*
|
|
* Fill this contiguous range into the partial page map.
|
|
*/
|
|
for (i = 0; i < error; i++) {
|
|
const int plen = min_t(size_t, len, PAGE_SIZE - off);
|
|
|
|
partial[buffers].offset = off;
|
|
partial[buffers].len = plen;
|
|
|
|
off = 0;
|
|
len -= plen;
|
|
buffers++;
|
|
}
|
|
|
|
/*
|
|
* We didn't complete this iov, stop here since it probably
|
|
* means we have to move some of this into a pipe to
|
|
* be able to continue.
|
|
*/
|
|
if (len)
|
|
break;
|
|
|
|
/*
|
|
* Don't continue if we mapped fewer pages than we asked for,
|
|
* or if we mapped the max number of pages that we have
|
|
* room for.
|
|
*/
|
|
if (error < npages || buffers == pipe_buffers)
|
|
break;
|
|
|
|
nr_vecs--;
|
|
iov++;
|
|
}
|
|
|
|
if (buffers)
|
|
return buffers;
|
|
|
|
return error;
|
|
}
|
|
|
|
static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
|
|
struct splice_desc *sd)
|
|
{
|
|
int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data);
|
|
return n == sd->len ? n : -EFAULT;
|
|
}
|
|
|
|
/*
|
|
* For lack of a better implementation, implement vmsplice() to userspace
|
|
* as a simple copy of the pipes pages to the user iov.
|
|
*/
|
|
static long vmsplice_to_user(struct file *file, const struct iovec __user *uiov,
|
|
unsigned long nr_segs, unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
struct splice_desc sd;
|
|
long ret;
|
|
struct iovec iovstack[UIO_FASTIOV];
|
|
struct iovec *iov = iovstack;
|
|
struct iov_iter iter;
|
|
ssize_t count;
|
|
|
|
pipe = get_pipe_info(file);
|
|
if (!pipe)
|
|
return -EBADF;
|
|
|
|
ret = rw_copy_check_uvector(READ, uiov, nr_segs,
|
|
ARRAY_SIZE(iovstack), iovstack, &iov);
|
|
if (ret <= 0)
|
|
goto out;
|
|
|
|
count = ret;
|
|
iov_iter_init(&iter, READ, iov, nr_segs, count);
|
|
|
|
sd.len = 0;
|
|
sd.total_len = count;
|
|
sd.flags = flags;
|
|
sd.u.data = &iter;
|
|
sd.pos = 0;
|
|
|
|
pipe_lock(pipe);
|
|
ret = __splice_from_pipe(pipe, &sd, pipe_to_user);
|
|
pipe_unlock(pipe);
|
|
|
|
out:
|
|
if (iov != iovstack)
|
|
kfree(iov);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* vmsplice splices a user address range into a pipe. It can be thought of
|
|
* as splice-from-memory, where the regular splice is splice-from-file (or
|
|
* to file). In both cases the output is a pipe, naturally.
|
|
*/
|
|
static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
|
|
unsigned long nr_segs, unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
struct page *pages[PIPE_DEF_BUFFERS];
|
|
struct partial_page partial[PIPE_DEF_BUFFERS];
|
|
struct splice_pipe_desc spd = {
|
|
.pages = pages,
|
|
.partial = partial,
|
|
.nr_pages_max = PIPE_DEF_BUFFERS,
|
|
.flags = flags,
|
|
.ops = &user_page_pipe_buf_ops,
|
|
.spd_release = spd_release_page,
|
|
};
|
|
long ret;
|
|
|
|
pipe = get_pipe_info(file);
|
|
if (!pipe)
|
|
return -EBADF;
|
|
|
|
if (splice_grow_spd(pipe, &spd))
|
|
return -ENOMEM;
|
|
|
|
spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
|
|
spd.partial, false,
|
|
spd.nr_pages_max);
|
|
if (spd.nr_pages <= 0)
|
|
ret = spd.nr_pages;
|
|
else
|
|
ret = splice_to_pipe(pipe, &spd);
|
|
|
|
splice_shrink_spd(&spd);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Note that vmsplice only really supports true splicing _from_ user memory
|
|
* to a pipe, not the other way around. Splicing from user memory is a simple
|
|
* operation that can be supported without any funky alignment restrictions
|
|
* or nasty vm tricks. We simply map in the user memory and fill them into
|
|
* a pipe. The reverse isn't quite as easy, though. There are two possible
|
|
* solutions for that:
|
|
*
|
|
* - memcpy() the data internally, at which point we might as well just
|
|
* do a regular read() on the buffer anyway.
|
|
* - Lots of nasty vm tricks, that are neither fast nor flexible (it
|
|
* has restriction limitations on both ends of the pipe).
|
|
*
|
|
* Currently we punt and implement it as a normal copy, see pipe_to_user().
|
|
*
|
|
*/
|
|
SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
|
|
unsigned long, nr_segs, unsigned int, flags)
|
|
{
|
|
struct fd f;
|
|
long error;
|
|
|
|
if (unlikely(nr_segs > UIO_MAXIOV))
|
|
return -EINVAL;
|
|
else if (unlikely(!nr_segs))
|
|
return 0;
|
|
|
|
error = -EBADF;
|
|
f = fdget(fd);
|
|
if (f.file) {
|
|
if (f.file->f_mode & FMODE_WRITE)
|
|
error = vmsplice_to_pipe(f.file, iov, nr_segs, flags);
|
|
else if (f.file->f_mode & FMODE_READ)
|
|
error = vmsplice_to_user(f.file, iov, nr_segs, flags);
|
|
|
|
fdput(f);
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
#ifdef CONFIG_COMPAT
|
|
COMPAT_SYSCALL_DEFINE4(vmsplice, int, fd, const struct compat_iovec __user *, iov32,
|
|
unsigned int, nr_segs, unsigned int, flags)
|
|
{
|
|
unsigned i;
|
|
struct iovec __user *iov;
|
|
if (nr_segs > UIO_MAXIOV)
|
|
return -EINVAL;
|
|
iov = compat_alloc_user_space(nr_segs * sizeof(struct iovec));
|
|
for (i = 0; i < nr_segs; i++) {
|
|
struct compat_iovec v;
|
|
if (get_user(v.iov_base, &iov32[i].iov_base) ||
|
|
get_user(v.iov_len, &iov32[i].iov_len) ||
|
|
put_user(compat_ptr(v.iov_base), &iov[i].iov_base) ||
|
|
put_user(v.iov_len, &iov[i].iov_len))
|
|
return -EFAULT;
|
|
}
|
|
return sys_vmsplice(fd, iov, nr_segs, flags);
|
|
}
|
|
#endif
|
|
|
|
SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
|
|
int, fd_out, loff_t __user *, off_out,
|
|
size_t, len, unsigned int, flags)
|
|
{
|
|
struct fd in, out;
|
|
long error;
|
|
|
|
if (unlikely(!len))
|
|
return 0;
|
|
|
|
error = -EBADF;
|
|
in = fdget(fd_in);
|
|
if (in.file) {
|
|
if (in.file->f_mode & FMODE_READ) {
|
|
out = fdget(fd_out);
|
|
if (out.file) {
|
|
if (out.file->f_mode & FMODE_WRITE)
|
|
error = do_splice(in.file, off_in,
|
|
out.file, off_out,
|
|
len, flags);
|
|
fdput(out);
|
|
}
|
|
}
|
|
fdput(in);
|
|
}
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* Make sure there's data to read. Wait for input if we can, otherwise
|
|
* return an appropriate error.
|
|
*/
|
|
static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* Check ->nrbufs without the inode lock first. This function
|
|
* is speculative anyways, so missing one is ok.
|
|
*/
|
|
if (pipe->nrbufs)
|
|
return 0;
|
|
|
|
ret = 0;
|
|
pipe_lock(pipe);
|
|
|
|
while (!pipe->nrbufs) {
|
|
if (signal_pending(current)) {
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
if (!pipe->writers)
|
|
break;
|
|
if (!pipe->waiting_writers) {
|
|
if (flags & SPLICE_F_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
}
|
|
pipe_wait(pipe);
|
|
}
|
|
|
|
pipe_unlock(pipe);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Make sure there's writeable room. Wait for room if we can, otherwise
|
|
* return an appropriate error.
|
|
*/
|
|
static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* Check ->nrbufs without the inode lock first. This function
|
|
* is speculative anyways, so missing one is ok.
|
|
*/
|
|
if (pipe->nrbufs < pipe->buffers)
|
|
return 0;
|
|
|
|
ret = 0;
|
|
pipe_lock(pipe);
|
|
|
|
while (pipe->nrbufs >= pipe->buffers) {
|
|
if (!pipe->readers) {
|
|
send_sig(SIGPIPE, current, 0);
|
|
ret = -EPIPE;
|
|
break;
|
|
}
|
|
if (flags & SPLICE_F_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
if (signal_pending(current)) {
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
pipe->waiting_writers++;
|
|
pipe_wait(pipe);
|
|
pipe->waiting_writers--;
|
|
}
|
|
|
|
pipe_unlock(pipe);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Splice contents of ipipe to opipe.
|
|
*/
|
|
static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
|
|
struct pipe_inode_info *opipe,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
struct pipe_buffer *ibuf, *obuf;
|
|
int ret = 0, nbuf;
|
|
bool input_wakeup = false;
|
|
|
|
|
|
retry:
|
|
ret = ipipe_prep(ipipe, flags);
|
|
if (ret)
|
|
return ret;
|
|
|
|
ret = opipe_prep(opipe, flags);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/*
|
|
* Potential ABBA deadlock, work around it by ordering lock
|
|
* grabbing by pipe info address. Otherwise two different processes
|
|
* could deadlock (one doing tee from A -> B, the other from B -> A).
|
|
*/
|
|
pipe_double_lock(ipipe, opipe);
|
|
|
|
do {
|
|
if (!opipe->readers) {
|
|
send_sig(SIGPIPE, current, 0);
|
|
if (!ret)
|
|
ret = -EPIPE;
|
|
break;
|
|
}
|
|
|
|
if (!ipipe->nrbufs && !ipipe->writers)
|
|
break;
|
|
|
|
/*
|
|
* Cannot make any progress, because either the input
|
|
* pipe is empty or the output pipe is full.
|
|
*/
|
|
if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
|
|
/* Already processed some buffers, break */
|
|
if (ret)
|
|
break;
|
|
|
|
if (flags & SPLICE_F_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* We raced with another reader/writer and haven't
|
|
* managed to process any buffers. A zero return
|
|
* value means EOF, so retry instead.
|
|
*/
|
|
pipe_unlock(ipipe);
|
|
pipe_unlock(opipe);
|
|
goto retry;
|
|
}
|
|
|
|
ibuf = ipipe->bufs + ipipe->curbuf;
|
|
nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
|
|
obuf = opipe->bufs + nbuf;
|
|
|
|
if (len >= ibuf->len) {
|
|
/*
|
|
* Simply move the whole buffer from ipipe to opipe
|
|
*/
|
|
*obuf = *ibuf;
|
|
ibuf->ops = NULL;
|
|
opipe->nrbufs++;
|
|
ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
|
|
ipipe->nrbufs--;
|
|
input_wakeup = true;
|
|
} else {
|
|
/*
|
|
* Get a reference to this pipe buffer,
|
|
* so we can copy the contents over.
|
|
*/
|
|
ibuf->ops->get(ipipe, ibuf);
|
|
*obuf = *ibuf;
|
|
|
|
/*
|
|
* Don't inherit the gift flag, we need to
|
|
* prevent multiple steals of this page.
|
|
*/
|
|
obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
|
|
|
|
obuf->len = len;
|
|
opipe->nrbufs++;
|
|
ibuf->offset += obuf->len;
|
|
ibuf->len -= obuf->len;
|
|
}
|
|
ret += obuf->len;
|
|
len -= obuf->len;
|
|
} while (len);
|
|
|
|
pipe_unlock(ipipe);
|
|
pipe_unlock(opipe);
|
|
|
|
/*
|
|
* If we put data in the output pipe, wakeup any potential readers.
|
|
*/
|
|
if (ret > 0)
|
|
wakeup_pipe_readers(opipe);
|
|
|
|
if (input_wakeup)
|
|
wakeup_pipe_writers(ipipe);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Link contents of ipipe to opipe.
|
|
*/
|
|
static int link_pipe(struct pipe_inode_info *ipipe,
|
|
struct pipe_inode_info *opipe,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
struct pipe_buffer *ibuf, *obuf;
|
|
int ret = 0, i = 0, nbuf;
|
|
|
|
/*
|
|
* Potential ABBA deadlock, work around it by ordering lock
|
|
* grabbing by pipe info address. Otherwise two different processes
|
|
* could deadlock (one doing tee from A -> B, the other from B -> A).
|
|
*/
|
|
pipe_double_lock(ipipe, opipe);
|
|
|
|
do {
|
|
if (!opipe->readers) {
|
|
send_sig(SIGPIPE, current, 0);
|
|
if (!ret)
|
|
ret = -EPIPE;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* If we have iterated all input buffers or ran out of
|
|
* output room, break.
|
|
*/
|
|
if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
|
|
break;
|
|
|
|
ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
|
|
nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
|
|
|
|
/*
|
|
* Get a reference to this pipe buffer,
|
|
* so we can copy the contents over.
|
|
*/
|
|
ibuf->ops->get(ipipe, ibuf);
|
|
|
|
obuf = opipe->bufs + nbuf;
|
|
*obuf = *ibuf;
|
|
|
|
/*
|
|
* Don't inherit the gift flag, we need to
|
|
* prevent multiple steals of this page.
|
|
*/
|
|
obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
|
|
|
|
if (obuf->len > len)
|
|
obuf->len = len;
|
|
|
|
opipe->nrbufs++;
|
|
ret += obuf->len;
|
|
len -= obuf->len;
|
|
i++;
|
|
} while (len);
|
|
|
|
/*
|
|
* return EAGAIN if we have the potential of some data in the
|
|
* future, otherwise just return 0
|
|
*/
|
|
if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
|
|
ret = -EAGAIN;
|
|
|
|
pipe_unlock(ipipe);
|
|
pipe_unlock(opipe);
|
|
|
|
/*
|
|
* If we put data in the output pipe, wakeup any potential readers.
|
|
*/
|
|
if (ret > 0)
|
|
wakeup_pipe_readers(opipe);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This is a tee(1) implementation that works on pipes. It doesn't copy
|
|
* any data, it simply references the 'in' pages on the 'out' pipe.
|
|
* The 'flags' used are the SPLICE_F_* variants, currently the only
|
|
* applicable one is SPLICE_F_NONBLOCK.
|
|
*/
|
|
static long do_tee(struct file *in, struct file *out, size_t len,
|
|
unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *ipipe = get_pipe_info(in);
|
|
struct pipe_inode_info *opipe = get_pipe_info(out);
|
|
int ret = -EINVAL;
|
|
|
|
/*
|
|
* Duplicate the contents of ipipe to opipe without actually
|
|
* copying the data.
|
|
*/
|
|
if (ipipe && opipe && ipipe != opipe) {
|
|
/*
|
|
* Keep going, unless we encounter an error. The ipipe/opipe
|
|
* ordering doesn't really matter.
|
|
*/
|
|
ret = ipipe_prep(ipipe, flags);
|
|
if (!ret) {
|
|
ret = opipe_prep(opipe, flags);
|
|
if (!ret)
|
|
ret = link_pipe(ipipe, opipe, len, flags);
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
|
|
{
|
|
struct fd in;
|
|
int error;
|
|
|
|
if (unlikely(!len))
|
|
return 0;
|
|
|
|
error = -EBADF;
|
|
in = fdget(fdin);
|
|
if (in.file) {
|
|
if (in.file->f_mode & FMODE_READ) {
|
|
struct fd out = fdget(fdout);
|
|
if (out.file) {
|
|
if (out.file->f_mode & FMODE_WRITE)
|
|
error = do_tee(in.file, out.file,
|
|
len, flags);
|
|
fdput(out);
|
|
}
|
|
}
|
|
fdput(in);
|
|
}
|
|
|
|
return error;
|
|
}
|