![Ingo Molnar](/assets/img/avatar_default.png)
- capitalize consistently - end sentences in one way or another - update comment text to match the implementation Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Jens Axboe <axboe@suse.de>
964 lines
21 KiB
C
964 lines
21 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@suse.de>
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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/pipe_fs_i.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/buffer_head.h>
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#include <linux/module.h>
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#include <linux/syscalls.h>
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/*
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* Passed to the actors
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*/
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struct splice_desc {
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unsigned int len, total_len; /* current and remaining length */
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unsigned int flags; /* splice flags */
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struct file *file; /* file to read/write */
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loff_t pos; /* file position */
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};
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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 *info,
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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 = page_mapping(page);
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WARN_ON(!PageLocked(page));
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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 writeback
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* completing on this page, since we'll remove it from the pagecache.
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* Otherwise truncate wont wait on the page, allowing the disk
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* blocks to be reused by someone else before we actually wrote our
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* data to them. fs corruption ensues.
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*/
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wait_on_page_writeback(page);
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if (PagePrivate(page))
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try_to_release_page(page, mapping_gfp_mask(mapping));
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if (!remove_mapping(mapping, page))
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return 1;
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buf->flags |= PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU;
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return 0;
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}
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static void page_cache_pipe_buf_release(struct pipe_inode_info *info,
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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->page = NULL;
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buf->flags &= ~(PIPE_BUF_FLAG_STOLEN | PIPE_BUF_FLAG_LRU);
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}
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static void *page_cache_pipe_buf_map(struct file *file,
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struct pipe_inode_info *info,
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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, fall through to mapping.
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*/
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unlock_page(page);
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}
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return kmap(page);
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error:
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unlock_page(page);
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return ERR_PTR(err);
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}
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static void page_cache_pipe_buf_unmap(struct pipe_inode_info *info,
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struct pipe_buffer *buf)
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{
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kunmap(buf->page);
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}
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static struct pipe_buf_operations page_cache_pipe_buf_ops = {
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.can_merge = 0,
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.map = page_cache_pipe_buf_map,
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.unmap = page_cache_pipe_buf_unmap,
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.release = page_cache_pipe_buf_release,
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.steal = page_cache_pipe_buf_steal,
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};
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/*
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* Pipe output worker. This sets up our pipe format with the page cache
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* pipe buffer operations. Otherwise very similar to the regular pipe_writev().
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*/
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static ssize_t move_to_pipe(struct pipe_inode_info *pipe, struct page **pages,
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int nr_pages, unsigned long offset,
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unsigned long len, unsigned int flags)
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{
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int ret, do_wakeup, i;
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ret = 0;
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do_wakeup = 0;
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i = 0;
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if (pipe->inode)
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mutex_lock(&pipe->inode->i_mutex);
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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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struct page *page = pages[i++];
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unsigned long this_len;
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this_len = PAGE_CACHE_SIZE - offset;
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if (this_len > len)
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this_len = len;
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buf->page = page;
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buf->offset = offset;
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buf->len = this_len;
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buf->ops = &page_cache_pipe_buf_ops;
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pipe->nrbufs++;
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if (pipe->inode)
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do_wakeup = 1;
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ret += this_len;
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len -= this_len;
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offset = 0;
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if (!--nr_pages)
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break;
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if (!len)
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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 (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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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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while (i < nr_pages)
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page_cache_release(pages[i++]);
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return ret;
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}
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static int
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__generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
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size_t len, unsigned int flags)
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{
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struct address_space *mapping = in->f_mapping;
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unsigned int offset, nr_pages;
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struct page *pages[PIPE_BUFFERS];
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struct page *page;
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pgoff_t index;
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int i, error;
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index = in->f_pos >> PAGE_CACHE_SHIFT;
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offset = in->f_pos & ~PAGE_CACHE_MASK;
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nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
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if (nr_pages > PIPE_BUFFERS)
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nr_pages = PIPE_BUFFERS;
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/*
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* Initiate read-ahead on this page range. however, don't call into
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* read-ahead if this is a non-zero offset (we are likely doing small
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* chunk splice and the page is already there) for a single page.
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*/
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if (!offset || nr_pages > 1)
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do_page_cache_readahead(mapping, in, index, nr_pages);
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/*
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* Now fill in the holes:
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*/
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error = 0;
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for (i = 0; i < nr_pages; i++, index++) {
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find_page:
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/*
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* lookup the page for this index
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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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* If in nonblock mode then dont block on
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* readpage (we've kicked readahead so there
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* will be asynchronous progress):
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*/
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if (flags & SPLICE_F_NONBLOCK)
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break;
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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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mapping_gfp_mask(mapping));
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if (unlikely(error)) {
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page_cache_release(page);
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break;
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}
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goto readpage;
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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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* page was truncated, stop here. if this isn't the
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* first page, we'll just complete what we already
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* added
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*/
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if (!page->mapping) {
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unlock_page(page);
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page_cache_release(page);
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break;
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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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readpage:
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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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page_cache_release(page);
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if (error == AOP_TRUNCATED_PAGE)
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goto find_page;
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break;
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}
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}
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fill_it:
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pages[i] = page;
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}
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if (i)
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return move_to_pipe(pipe, pages, i, offset, len, flags);
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return error;
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}
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/**
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* generic_file_splice_read - splice data from file to a pipe
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* @in: file to splice from
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* @pipe: pipe to splice to
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* @len: number of bytes to splice
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* @flags: splice modifier flags
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*
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* Will read pages from given file and fill them into a pipe.
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*/
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ssize_t generic_file_splice_read(struct file *in, struct pipe_inode_info *pipe,
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size_t len, unsigned int flags)
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{
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ssize_t spliced;
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int ret;
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ret = 0;
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spliced = 0;
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while (len) {
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ret = __generic_file_splice_read(in, pipe, len, flags);
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if (ret <= 0)
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break;
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in->f_pos += ret;
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len -= ret;
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spliced += ret;
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if (!(flags & SPLICE_F_NONBLOCK))
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continue;
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ret = -EAGAIN;
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break;
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}
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if (spliced)
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return spliced;
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return ret;
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}
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EXPORT_SYMBOL(generic_file_splice_read);
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/*
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* Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
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* using sendpage().
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*/
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static int pipe_to_sendpage(struct pipe_inode_info *info,
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struct pipe_buffer *buf, struct splice_desc *sd)
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{
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struct file *file = sd->file;
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loff_t pos = sd->pos;
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unsigned int offset;
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ssize_t ret;
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void *ptr;
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int more;
|
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/*
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* Sub-optimal, but we are limited by the pipe ->map. We don't
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* need a kmap'ed buffer here, we just want to make sure we
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* have the page pinned if the pipe page originates from the
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* page cache.
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*/
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ptr = buf->ops->map(file, info, buf);
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if (IS_ERR(ptr))
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return PTR_ERR(ptr);
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|
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offset = pos & ~PAGE_CACHE_MASK;
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more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
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ret = file->f_op->sendpage(file, buf->page, offset, sd->len, &pos,more);
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buf->ops->unmap(info, buf);
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if (ret == sd->len)
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return 0;
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return -EIO;
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}
|
|
|
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/*
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* This is a little more tricky than the file -> pipe splicing. There are
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* basically three cases:
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*
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* - Destination page already exists in the address space and there
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* are users of it. For that case we have no other option that
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* copying the data. Tough luck.
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* - Destination page already exists in the address space, but there
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* are no users of it. Make sure it's uptodate, then drop it. Fall
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* through to last case.
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* - Destination page does not exist, we can add the pipe page to
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* the page cache and avoid the copy.
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*
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* If asked to move pages to the output file (SPLICE_F_MOVE is set in
|
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* sd->flags), we attempt to migrate pages from the pipe to the output
|
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* file address space page cache. This is possible if no one else has
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* the pipe page referenced outside of the pipe and page cache. If
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* SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
|
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* a new page in the output file page cache and fill/dirty that.
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*/
|
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static int pipe_to_file(struct pipe_inode_info *info, struct pipe_buffer *buf,
|
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struct splice_desc *sd)
|
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{
|
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struct file *file = sd->file;
|
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struct address_space *mapping = file->f_mapping;
|
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gfp_t gfp_mask = mapping_gfp_mask(mapping);
|
|
unsigned int offset;
|
|
struct page *page;
|
|
pgoff_t index;
|
|
char *src;
|
|
int ret;
|
|
|
|
/*
|
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* make sure the data in this buffer is uptodate
|
|
*/
|
|
src = buf->ops->map(file, info, buf);
|
|
if (IS_ERR(src))
|
|
return PTR_ERR(src);
|
|
|
|
index = sd->pos >> PAGE_CACHE_SHIFT;
|
|
offset = sd->pos & ~PAGE_CACHE_MASK;
|
|
|
|
/*
|
|
* Reuse buf page, if SPLICE_F_MOVE is set.
|
|
*/
|
|
if (sd->flags & SPLICE_F_MOVE) {
|
|
/*
|
|
* If steal succeeds, buf->page is now pruned from the vm
|
|
* side (LRU and page cache) and we can reuse it.
|
|
*/
|
|
if (buf->ops->steal(info, buf))
|
|
goto find_page;
|
|
|
|
/*
|
|
* this will also set the page locked
|
|
*/
|
|
page = buf->page;
|
|
if (add_to_page_cache(page, mapping, index, gfp_mask))
|
|
goto find_page;
|
|
|
|
if (!(buf->flags & PIPE_BUF_FLAG_LRU))
|
|
lru_cache_add(page);
|
|
} else {
|
|
find_page:
|
|
ret = -ENOMEM;
|
|
page = find_or_create_page(mapping, index, gfp_mask);
|
|
if (!page)
|
|
goto out_nomem;
|
|
|
|
/*
|
|
* If the page is uptodate, it is also locked. If it isn't
|
|
* uptodate, we can mark it uptodate if we are filling the
|
|
* full page. Otherwise we need to read it in first...
|
|
*/
|
|
if (!PageUptodate(page)) {
|
|
if (sd->len < PAGE_CACHE_SIZE) {
|
|
ret = mapping->a_ops->readpage(file, page);
|
|
if (unlikely(ret))
|
|
goto out;
|
|
|
|
lock_page(page);
|
|
|
|
if (!PageUptodate(page)) {
|
|
/*
|
|
* Page got invalidated, repeat.
|
|
*/
|
|
if (!page->mapping) {
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
goto find_page;
|
|
}
|
|
ret = -EIO;
|
|
goto out;
|
|
}
|
|
} else {
|
|
WARN_ON(!PageLocked(page));
|
|
SetPageUptodate(page);
|
|
}
|
|
}
|
|
}
|
|
|
|
ret = mapping->a_ops->prepare_write(file, page, 0, sd->len);
|
|
if (ret == AOP_TRUNCATED_PAGE) {
|
|
page_cache_release(page);
|
|
goto find_page;
|
|
} else if (ret)
|
|
goto out;
|
|
|
|
if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
|
|
char *dst = kmap_atomic(page, KM_USER0);
|
|
|
|
memcpy(dst + offset, src + buf->offset, sd->len);
|
|
flush_dcache_page(page);
|
|
kunmap_atomic(dst, KM_USER0);
|
|
}
|
|
|
|
ret = mapping->a_ops->commit_write(file, page, 0, sd->len);
|
|
if (ret == AOP_TRUNCATED_PAGE) {
|
|
page_cache_release(page);
|
|
goto find_page;
|
|
} else if (ret)
|
|
goto out;
|
|
|
|
mark_page_accessed(page);
|
|
balance_dirty_pages_ratelimited(mapping);
|
|
out:
|
|
if (!(buf->flags & PIPE_BUF_FLAG_STOLEN)) {
|
|
page_cache_release(page);
|
|
unlock_page(page);
|
|
}
|
|
out_nomem:
|
|
buf->ops->unmap(info, buf);
|
|
return ret;
|
|
}
|
|
|
|
typedef int (splice_actor)(struct pipe_inode_info *, struct pipe_buffer *,
|
|
struct splice_desc *);
|
|
|
|
/*
|
|
* Pipe input worker. Most of this logic works like a regular pipe, the
|
|
* key here is the 'actor' worker passed in that actually moves the data
|
|
* to the wanted destination. See pipe_to_file/pipe_to_sendpage above.
|
|
*/
|
|
static ssize_t move_from_pipe(struct pipe_inode_info *pipe, struct file *out,
|
|
size_t len, unsigned int flags,
|
|
splice_actor *actor)
|
|
{
|
|
int ret, do_wakeup, err;
|
|
struct splice_desc sd;
|
|
|
|
ret = 0;
|
|
do_wakeup = 0;
|
|
|
|
sd.total_len = len;
|
|
sd.flags = flags;
|
|
sd.file = out;
|
|
sd.pos = out->f_pos;
|
|
|
|
if (pipe->inode)
|
|
mutex_lock(&pipe->inode->i_mutex);
|
|
|
|
for (;;) {
|
|
if (pipe->nrbufs) {
|
|
struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
|
|
struct pipe_buf_operations *ops = buf->ops;
|
|
|
|
sd.len = buf->len;
|
|
if (sd.len > sd.total_len)
|
|
sd.len = sd.total_len;
|
|
|
|
err = actor(pipe, buf, &sd);
|
|
if (err) {
|
|
if (!ret && err != -ENODATA)
|
|
ret = err;
|
|
|
|
break;
|
|
}
|
|
|
|
ret += sd.len;
|
|
buf->offset += sd.len;
|
|
buf->len -= sd.len;
|
|
|
|
if (!buf->len) {
|
|
buf->ops = NULL;
|
|
ops->release(pipe, buf);
|
|
pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1);
|
|
pipe->nrbufs--;
|
|
if (pipe->inode)
|
|
do_wakeup = 1;
|
|
}
|
|
|
|
sd.pos += sd.len;
|
|
sd.total_len -= sd.len;
|
|
if (!sd.total_len)
|
|
break;
|
|
}
|
|
|
|
if (pipe->nrbufs)
|
|
continue;
|
|
if (!pipe->writers)
|
|
break;
|
|
if (!pipe->waiting_writers) {
|
|
if (ret)
|
|
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_writers, SIGIO, POLL_OUT);
|
|
do_wakeup = 0;
|
|
}
|
|
|
|
pipe_wait(pipe);
|
|
}
|
|
|
|
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_writers, SIGIO, POLL_OUT);
|
|
}
|
|
|
|
out->f_pos = sd.pos;
|
|
return ret;
|
|
|
|
}
|
|
|
|
/**
|
|
* generic_file_splice_write - splice data from a pipe to a file
|
|
* @pipe: pipe info
|
|
* @out: file to write to
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* Will either move or copy pages (determined by @flags options) from
|
|
* the given pipe inode to the given file.
|
|
*
|
|
*/
|
|
ssize_t
|
|
generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
struct address_space *mapping = out->f_mapping;
|
|
ssize_t ret;
|
|
|
|
ret = move_from_pipe(pipe, out, len, flags, pipe_to_file);
|
|
|
|
/*
|
|
* If file or inode is SYNC and we actually wrote some data, sync it.
|
|
*/
|
|
if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(mapping->host))
|
|
&& ret > 0) {
|
|
struct inode *inode = mapping->host;
|
|
int err;
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
err = generic_osync_inode(mapping->host, mapping,
|
|
OSYNC_METADATA|OSYNC_DATA);
|
|
mutex_unlock(&inode->i_mutex);
|
|
|
|
if (err)
|
|
ret = err;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_file_splice_write);
|
|
|
|
/**
|
|
* generic_splice_sendpage - splice data from a pipe to a socket
|
|
* @inode: pipe inode
|
|
* @out: socket to write to
|
|
* @len: number of bytes to splice
|
|
* @flags: splice modifier flags
|
|
*
|
|
* 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,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
return move_from_pipe(pipe, out, 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,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
loff_t pos;
|
|
int ret;
|
|
|
|
if (unlikely(!out->f_op || !out->f_op->splice_write))
|
|
return -EINVAL;
|
|
|
|
if (unlikely(!(out->f_mode & FMODE_WRITE)))
|
|
return -EBADF;
|
|
|
|
pos = out->f_pos;
|
|
|
|
ret = rw_verify_area(WRITE, out, &pos, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
return out->f_op->splice_write(pipe, out, len, flags);
|
|
}
|
|
|
|
/*
|
|
* Attempt to initiate a splice from a file to a pipe.
|
|
*/
|
|
static long do_splice_to(struct file *in, struct pipe_inode_info *pipe,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
loff_t pos, isize, left;
|
|
int ret;
|
|
|
|
if (unlikely(!in->f_op || !in->f_op->splice_read))
|
|
return -EINVAL;
|
|
|
|
if (unlikely(!(in->f_mode & FMODE_READ)))
|
|
return -EBADF;
|
|
|
|
pos = in->f_pos;
|
|
|
|
ret = rw_verify_area(READ, in, &pos, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
isize = i_size_read(in->f_mapping->host);
|
|
if (unlikely(in->f_pos >= isize))
|
|
return 0;
|
|
|
|
left = isize - in->f_pos;
|
|
if (unlikely(left < len))
|
|
len = left;
|
|
|
|
return in->f_op->splice_read(in, pipe, len, flags);
|
|
}
|
|
|
|
long do_splice_direct(struct file *in, struct file *out, size_t len,
|
|
unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
long ret, bytes;
|
|
umode_t i_mode;
|
|
int i;
|
|
|
|
/*
|
|
* 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 = in->f_dentry->d_inode->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(NULL);
|
|
if (!pipe)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* We don't have an immediate reader, but we'll read the stuff
|
|
* out of the pipe right after the move_to_pipe(). So set
|
|
* PIPE_READERS appropriately.
|
|
*/
|
|
pipe->readers = 1;
|
|
|
|
current->splice_pipe = pipe;
|
|
}
|
|
|
|
/*
|
|
* Do the splice.
|
|
*/
|
|
ret = 0;
|
|
bytes = 0;
|
|
|
|
while (len) {
|
|
size_t read_len, max_read_len;
|
|
|
|
/*
|
|
* Do at most PIPE_BUFFERS pages worth of transfer:
|
|
*/
|
|
max_read_len = min(len, (size_t)(PIPE_BUFFERS*PAGE_SIZE));
|
|
|
|
ret = do_splice_to(in, pipe, max_read_len, flags);
|
|
if (unlikely(ret < 0))
|
|
goto out_release;
|
|
|
|
read_len = ret;
|
|
|
|
/*
|
|
* 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 = do_splice_from(pipe, out, read_len,
|
|
flags & ~SPLICE_F_NONBLOCK);
|
|
if (unlikely(ret < 0))
|
|
goto out_release;
|
|
|
|
bytes += ret;
|
|
len -= ret;
|
|
|
|
/*
|
|
* In nonblocking mode, if we got back a short read then
|
|
* that was due to either an IO error or due to the
|
|
* pagecache entry not being there. In the IO error case
|
|
* the _next_ splice attempt will produce a clean IO error
|
|
* return value (not a short read), so in both cases it's
|
|
* correct to break out of the loop here:
|
|
*/
|
|
if ((flags & SPLICE_F_NONBLOCK) && (read_len < max_read_len))
|
|
break;
|
|
}
|
|
|
|
pipe->nrbufs = pipe->curbuf = 0;
|
|
|
|
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;
|
|
}
|
|
}
|
|
pipe->nrbufs = pipe->curbuf = 0;
|
|
|
|
/*
|
|
* If we transferred some data, return the number of bytes:
|
|
*/
|
|
if (bytes > 0)
|
|
return bytes;
|
|
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(do_splice_direct);
|
|
|
|
/*
|
|
* 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 *pipe;
|
|
|
|
pipe = in->f_dentry->d_inode->i_pipe;
|
|
if (pipe) {
|
|
if (off_in)
|
|
return -ESPIPE;
|
|
if (off_out) {
|
|
if (out->f_op->llseek == no_llseek)
|
|
return -EINVAL;
|
|
if (copy_from_user(&out->f_pos, off_out,
|
|
sizeof(loff_t)))
|
|
return -EFAULT;
|
|
}
|
|
|
|
return do_splice_from(pipe, out, len, flags);
|
|
}
|
|
|
|
pipe = out->f_dentry->d_inode->i_pipe;
|
|
if (pipe) {
|
|
if (off_out)
|
|
return -ESPIPE;
|
|
if (off_in) {
|
|
if (in->f_op->llseek == no_llseek)
|
|
return -EINVAL;
|
|
if (copy_from_user(&in->f_pos, off_in, sizeof(loff_t)))
|
|
return -EFAULT;
|
|
}
|
|
|
|
return do_splice_to(in, pipe, len, flags);
|
|
}
|
|
|
|
return -EINVAL;
|
|
}
|
|
|
|
asmlinkage long sys_splice(int fd_in, loff_t __user *off_in,
|
|
int fd_out, loff_t __user *off_out,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
long error;
|
|
struct file *in, *out;
|
|
int fput_in, fput_out;
|
|
|
|
if (unlikely(!len))
|
|
return 0;
|
|
|
|
error = -EBADF;
|
|
in = fget_light(fd_in, &fput_in);
|
|
if (in) {
|
|
if (in->f_mode & FMODE_READ) {
|
|
out = fget_light(fd_out, &fput_out);
|
|
if (out) {
|
|
if (out->f_mode & FMODE_WRITE)
|
|
error = do_splice(in, off_in,
|
|
out, off_out,
|
|
len, flags);
|
|
fput_light(out, fput_out);
|
|
}
|
|
}
|
|
|
|
fput_light(in, fput_in);
|
|
}
|
|
|
|
return error;
|
|
}
|