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![Jens Axboe](/assets/img/avatar_default.png)
Otherwise we could be racing with truncate/mapping removal. Problem found/fixed by Nick Piggin <npiggin@suse.de>, logic rewritten by me. Signed-off-by: Jens Axboe <axboe@suse.de>
1502 lines
34 KiB
C
1502 lines
34 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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#include <linux/uio.h>
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struct partial_page {
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unsigned int offset;
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unsigned int len;
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};
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/*
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* Passed to splice_to_pipe
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*/
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struct splice_pipe_desc {
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struct page **pages; /* page map */
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struct partial_page *partial; /* pages[] may not be contig */
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int nr_pages; /* number of pages in map */
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unsigned int flags; /* splice flags */
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struct pipe_buf_operations *ops;/* ops associated with output pipe */
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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 *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 (PagePrivate(page))
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try_to_release_page(page, mapping_gfp_mask(mapping));
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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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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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static int page_cache_pipe_buf_pin(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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static struct pipe_buf_operations page_cache_pipe_buf_ops = {
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.can_merge = 0,
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.map = generic_pipe_buf_map,
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.unmap = generic_pipe_buf_unmap,
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.pin = page_cache_pipe_buf_pin,
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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 struct pipe_buf_operations user_page_pipe_buf_ops = {
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.can_merge = 0,
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.map = generic_pipe_buf_map,
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.unmap = generic_pipe_buf_unmap,
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.pin = generic_pipe_buf_pin,
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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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/*
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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 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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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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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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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->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->inode)
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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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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 (page_nr < spd->nr_pages)
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page_cache_release(spd->pages[page_nr++]);
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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, 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;
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struct page *pages[PIPE_BUFFERS];
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struct partial_page partial[PIPE_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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size_t total_len;
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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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.flags = flags,
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.ops = &page_cache_pipe_buf_ops,
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};
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index = *ppos >> PAGE_CACHE_SHIFT;
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loff = *ppos & ~PAGE_CACHE_MASK;
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nr_pages = (len + loff + 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 (!loff || nr_pages > 1)
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page_cache_readahead(mapping, &in->f_ra, 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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total_len = 0;
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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, pages);
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/*
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* If find_get_pages_contig() returned fewer pages than we needed,
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* allocate the rest.
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*/
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index += spd.nr_pages;
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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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* Make sure the read-ahead engine is notified
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* about this failure.
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*/
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handle_ra_miss(mapping, &in->f_ra, index);
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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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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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pages[spd.nr_pages++] = page;
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index++;
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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 = pages[page_nr];
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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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/*
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* If in nonblock mode then dont block on waiting
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* for an in-flight io page
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*/
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if (flags & SPLICE_F_NONBLOCK)
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break;
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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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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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/*
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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,
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* 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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*/
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if (error == AOP_TRUNCATED_PAGE)
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error = 0;
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break;
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}
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/*
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* i_size must be checked after ->readpage().
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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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|
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/*
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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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*/
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if (end_index == index) {
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loff = PAGE_CACHE_SIZE - (isize & ~PAGE_CACHE_MASK);
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if (total_len + loff > isize)
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break;
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/*
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* force quit after adding this page
|
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*/
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len = this_len;
|
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this_len = min(this_len, loff);
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loff = 0;
|
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}
|
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}
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fill_it:
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partial[page_nr].offset = loff;
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partial[page_nr].len = this_len;
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len -= this_len;
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total_len += this_len;
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loff = 0;
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spd.nr_pages++;
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index++;
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}
|
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|
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/*
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* Release any pages at the end, if we quit early. 'i' is how far
|
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* we got, 'nr_pages' is how many pages are in the map.
|
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*/
|
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while (page_nr < nr_pages)
|
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page_cache_release(pages[page_nr++]);
|
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|
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if (spd.nr_pages)
|
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return splice_to_pipe(pipe, &spd);
|
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|
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return error;
|
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}
|
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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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*/
|
|
ssize_t 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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ssize_t spliced;
|
|
int ret;
|
|
|
|
ret = 0;
|
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spliced = 0;
|
|
|
|
while (len) {
|
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ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
|
|
|
|
if (ret < 0)
|
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break;
|
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else if (!ret) {
|
|
if (spliced)
|
|
break;
|
|
if (flags & SPLICE_F_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
}
|
|
|
|
*ppos += ret;
|
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len -= ret;
|
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spliced += ret;
|
|
}
|
|
|
|
if (spliced)
|
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return spliced;
|
|
|
|
return ret;
|
|
}
|
|
|
|
EXPORT_SYMBOL(generic_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->file;
|
|
loff_t pos = sd->pos;
|
|
int ret, more;
|
|
|
|
ret = buf->ops->pin(pipe, buf);
|
|
if (!ret) {
|
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more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len;
|
|
|
|
ret = file->f_op->sendpage(file, buf->page, buf->offset,
|
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sd->len, &pos, more);
|
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}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This is a little more tricky than the file -> pipe splicing. There are
|
|
* basically three cases:
|
|
*
|
|
* - Destination page already exists in the address space and there
|
|
* are users of it. For that case we have no other option that
|
|
* copying the data. Tough luck.
|
|
* - Destination page already exists in the address space, but there
|
|
* are no users of it. Make sure it's uptodate, then drop it. Fall
|
|
* through to last case.
|
|
* - Destination page does not exist, we can add the pipe page to
|
|
* the page cache and avoid the copy.
|
|
*
|
|
* If asked to move pages to the output file (SPLICE_F_MOVE is set in
|
|
* sd->flags), we attempt to migrate pages from the pipe to the output
|
|
* file address space page cache. This is possible if no one else has
|
|
* the pipe page referenced outside of the pipe and page cache. If
|
|
* SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create
|
|
* a new page in the output file page cache and fill/dirty that.
|
|
*/
|
|
static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
|
|
struct splice_desc *sd)
|
|
{
|
|
struct file *file = sd->file;
|
|
struct address_space *mapping = file->f_mapping;
|
|
gfp_t gfp_mask = mapping_gfp_mask(mapping);
|
|
unsigned int offset, this_len;
|
|
struct page *page;
|
|
pgoff_t index;
|
|
int ret;
|
|
|
|
/*
|
|
* make sure the data in this buffer is uptodate
|
|
*/
|
|
ret = buf->ops->pin(pipe, buf);
|
|
if (unlikely(ret))
|
|
return ret;
|
|
|
|
index = sd->pos >> PAGE_CACHE_SHIFT;
|
|
offset = sd->pos & ~PAGE_CACHE_MASK;
|
|
|
|
this_len = sd->len;
|
|
if (this_len + offset > PAGE_CACHE_SIZE)
|
|
this_len = PAGE_CACHE_SIZE - offset;
|
|
|
|
/*
|
|
* Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full
|
|
* page.
|
|
*/
|
|
if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
|
|
/*
|
|
* If steal succeeds, buf->page is now pruned from the
|
|
* pagecache and we can reuse it. The page will also be
|
|
* locked on successful return.
|
|
*/
|
|
if (buf->ops->steal(pipe, buf))
|
|
goto find_page;
|
|
|
|
page = buf->page;
|
|
if (add_to_page_cache(page, mapping, index, gfp_mask)) {
|
|
unlock_page(page);
|
|
goto find_page;
|
|
}
|
|
|
|
page_cache_get(page);
|
|
|
|
if (!(buf->flags & PIPE_BUF_FLAG_LRU))
|
|
lru_cache_add(page);
|
|
} else {
|
|
find_page:
|
|
page = find_lock_page(mapping, index);
|
|
if (!page) {
|
|
ret = -ENOMEM;
|
|
page = page_cache_alloc_cold(mapping);
|
|
if (unlikely(!page))
|
|
goto out_nomem;
|
|
|
|
/*
|
|
* This will also lock the page
|
|
*/
|
|
ret = add_to_page_cache_lru(page, mapping, index,
|
|
gfp_mask);
|
|
if (unlikely(ret))
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* We get here with the page locked. If the page is also
|
|
* uptodate, we don't need to do more. If it isn't, we
|
|
* may need to bring it in if we are not going to overwrite
|
|
* the full page.
|
|
*/
|
|
if (!PageUptodate(page)) {
|
|
if (this_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
|
|
SetPageUptodate(page);
|
|
}
|
|
}
|
|
|
|
ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
|
|
if (unlikely(ret)) {
|
|
loff_t isize = i_size_read(mapping->host);
|
|
|
|
if (ret != AOP_TRUNCATED_PAGE)
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
if (ret == AOP_TRUNCATED_PAGE)
|
|
goto find_page;
|
|
|
|
/*
|
|
* prepare_write() may have instantiated a few blocks
|
|
* outside i_size. Trim these off again.
|
|
*/
|
|
if (sd->pos + this_len > isize)
|
|
vmtruncate(mapping->host, isize);
|
|
|
|
goto out;
|
|
}
|
|
|
|
if (buf->page != page) {
|
|
/*
|
|
* Careful, ->map() uses KM_USER0!
|
|
*/
|
|
char *src = buf->ops->map(pipe, buf, 1);
|
|
char *dst = kmap_atomic(page, KM_USER1);
|
|
|
|
memcpy(dst + offset, src + buf->offset, this_len);
|
|
flush_dcache_page(page);
|
|
kunmap_atomic(dst, KM_USER1);
|
|
buf->ops->unmap(pipe, buf, src);
|
|
}
|
|
|
|
ret = mapping->a_ops->commit_write(file, page, offset, offset+this_len);
|
|
if (!ret) {
|
|
/*
|
|
* Return the number of bytes written and mark page as
|
|
* accessed, we are now done!
|
|
*/
|
|
ret = this_len;
|
|
mark_page_accessed(page);
|
|
balance_dirty_pages_ratelimited(mapping);
|
|
} else if (ret == AOP_TRUNCATED_PAGE) {
|
|
page_cache_release(page);
|
|
goto find_page;
|
|
}
|
|
out:
|
|
page_cache_release(page);
|
|
unlock_page(page);
|
|
out_nomem:
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
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)
|
|
{
|
|
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 = *ppos;
|
|
|
|
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 <= 0) {
|
|
if (!ret && err != -ENODATA)
|
|
ret = err;
|
|
|
|
break;
|
|
}
|
|
|
|
ret += err;
|
|
buf->offset += err;
|
|
buf->len -= err;
|
|
|
|
sd.len -= err;
|
|
sd.pos += err;
|
|
sd.total_len -= err;
|
|
if (sd.len)
|
|
continue;
|
|
|
|
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;
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
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,
|
|
loff_t *ppos, size_t len, unsigned int flags)
|
|
{
|
|
struct address_space *mapping = out->f_mapping;
|
|
ssize_t ret;
|
|
|
|
ret = splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_file);
|
|
if (ret > 0) {
|
|
struct inode *inode = mapping->host;
|
|
|
|
*ppos += ret;
|
|
|
|
/*
|
|
* If file or inode is SYNC and we actually wrote some data,
|
|
* sync it.
|
|
*/
|
|
if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
|
int err;
|
|
|
|
mutex_lock(&inode->i_mutex);
|
|
err = generic_osync_inode(inode, 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,
|
|
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)
|
|
{
|
|
int ret;
|
|
|
|
if (unlikely(!out->f_op || !out->f_op->splice_write))
|
|
return -EINVAL;
|
|
|
|
if (unlikely(!(out->f_mode & FMODE_WRITE)))
|
|
return -EBADF;
|
|
|
|
ret = rw_verify_area(WRITE, out, ppos, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
return out->f_op->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)
|
|
{
|
|
loff_t 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;
|
|
|
|
ret = rw_verify_area(READ, in, ppos, len);
|
|
if (unlikely(ret < 0))
|
|
return ret;
|
|
|
|
isize = i_size_read(in->f_mapping->host);
|
|
if (unlikely(*ppos >= isize))
|
|
return 0;
|
|
|
|
left = isize - *ppos;
|
|
if (unlikely(left < len))
|
|
len = left;
|
|
|
|
return in->f_op->splice_read(in, ppos, pipe, len, flags);
|
|
}
|
|
|
|
long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
|
|
size_t len, unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *pipe;
|
|
long ret, bytes;
|
|
loff_t out_off;
|
|
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 splice_to_pipe(). So set
|
|
* PIPE_READERS appropriately.
|
|
*/
|
|
pipe->readers = 1;
|
|
|
|
current->splice_pipe = pipe;
|
|
}
|
|
|
|
/*
|
|
* Do the splice.
|
|
*/
|
|
ret = 0;
|
|
bytes = 0;
|
|
out_off = 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, ppos, 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, &out_off, 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;
|
|
loff_t offset, *off;
|
|
long ret;
|
|
|
|
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(&offset, off_out, sizeof(loff_t)))
|
|
return -EFAULT;
|
|
off = &offset;
|
|
} else
|
|
off = &out->f_pos;
|
|
|
|
ret = do_splice_from(pipe, out, off, len, flags);
|
|
|
|
if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
|
|
ret = -EFAULT;
|
|
|
|
return ret;
|
|
}
|
|
|
|
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(&offset, off_in, sizeof(loff_t)))
|
|
return -EFAULT;
|
|
off = &offset;
|
|
} else
|
|
off = &in->f_pos;
|
|
|
|
ret = do_splice_to(in, off, pipe, len, flags);
|
|
|
|
if (off_in && copy_to_user(off_in, off, 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, int aligned)
|
|
{
|
|
int buffers = 0, error = 0;
|
|
|
|
/*
|
|
* It's ok to take the mmap_sem for reading, even
|
|
* across a "get_user()".
|
|
*/
|
|
down_read(¤t->mm->mmap_sem);
|
|
|
|
while (nr_vecs) {
|
|
unsigned long off, npages;
|
|
void __user *base;
|
|
size_t len;
|
|
int i;
|
|
|
|
/*
|
|
* Get user address base and length for this iovec.
|
|
*/
|
|
error = get_user(base, &iov->iov_base);
|
|
if (unlikely(error))
|
|
break;
|
|
error = get_user(len, &iov->iov_len);
|
|
if (unlikely(error))
|
|
break;
|
|
|
|
/*
|
|
* Sanity check this iovec. 0 read succeeds.
|
|
*/
|
|
if (unlikely(!len))
|
|
break;
|
|
error = -EFAULT;
|
|
if (unlikely(!base))
|
|
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(current, current->mm,
|
|
(unsigned long) base, npages, 0, 0,
|
|
&pages[buffers], NULL);
|
|
|
|
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++;
|
|
}
|
|
|
|
up_read(¤t->mm->mmap_sem);
|
|
|
|
if (buffers)
|
|
return buffers;
|
|
|
|
return error;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* Note that vmsplice only supports 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).
|
|
*
|
|
* Alas, it isn't here.
|
|
*
|
|
*/
|
|
static long do_vmsplice(struct file *file, const struct iovec __user *iov,
|
|
unsigned long nr_segs, unsigned int flags)
|
|
{
|
|
struct pipe_inode_info *pipe = file->f_dentry->d_inode->i_pipe;
|
|
struct page *pages[PIPE_BUFFERS];
|
|
struct partial_page partial[PIPE_BUFFERS];
|
|
struct splice_pipe_desc spd = {
|
|
.pages = pages,
|
|
.partial = partial,
|
|
.flags = flags,
|
|
.ops = &user_page_pipe_buf_ops,
|
|
};
|
|
|
|
if (unlikely(!pipe))
|
|
return -EBADF;
|
|
if (unlikely(nr_segs > UIO_MAXIOV))
|
|
return -EINVAL;
|
|
else if (unlikely(!nr_segs))
|
|
return 0;
|
|
|
|
spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial,
|
|
flags & SPLICE_F_GIFT);
|
|
if (spd.nr_pages <= 0)
|
|
return spd.nr_pages;
|
|
|
|
return splice_to_pipe(pipe, &spd);
|
|
}
|
|
|
|
asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov,
|
|
unsigned long nr_segs, unsigned int flags)
|
|
{
|
|
struct file *file;
|
|
long error;
|
|
int fput;
|
|
|
|
error = -EBADF;
|
|
file = fget_light(fd, &fput);
|
|
if (file) {
|
|
if (file->f_mode & FMODE_WRITE)
|
|
error = do_vmsplice(file, iov, nr_segs, flags);
|
|
|
|
fput_light(file, fput);
|
|
}
|
|
|
|
return error;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* 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, do_wakeup, i, ipipe_first;
|
|
|
|
ret = do_wakeup = ipipe_first = 0;
|
|
|
|
/*
|
|
* Potential ABBA deadlock, work around it by ordering lock
|
|
* grabbing by inode address. Otherwise two different processes
|
|
* could deadlock (one doing tee from A -> B, the other from B -> A).
|
|
*/
|
|
if (ipipe->inode < opipe->inode) {
|
|
ipipe_first = 1;
|
|
mutex_lock(&ipipe->inode->i_mutex);
|
|
mutex_lock(&opipe->inode->i_mutex);
|
|
} else {
|
|
mutex_lock(&opipe->inode->i_mutex);
|
|
mutex_lock(&ipipe->inode->i_mutex);
|
|
}
|
|
|
|
for (i = 0;; i++) {
|
|
if (!opipe->readers) {
|
|
send_sig(SIGPIPE, current, 0);
|
|
if (!ret)
|
|
ret = -EPIPE;
|
|
break;
|
|
}
|
|
if (ipipe->nrbufs - i) {
|
|
ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1));
|
|
|
|
/*
|
|
* If we have room, fill this buffer
|
|
*/
|
|
if (opipe->nrbufs < PIPE_BUFFERS) {
|
|
int nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_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++;
|
|
do_wakeup = 1;
|
|
ret += obuf->len;
|
|
len -= obuf->len;
|
|
|
|
if (!len)
|
|
break;
|
|
if (opipe->nrbufs < PIPE_BUFFERS)
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* We have input available, but no output room.
|
|
* If we already copied data, return that. If we
|
|
* need to drop the opipe lock, it must be ordered
|
|
* last to avoid deadlocks.
|
|
*/
|
|
if ((flags & SPLICE_F_NONBLOCK) || !ipipe_first) {
|
|
if (!ret)
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
if (signal_pending(current)) {
|
|
if (!ret)
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
if (do_wakeup) {
|
|
smp_mb();
|
|
if (waitqueue_active(&opipe->wait))
|
|
wake_up_interruptible(&opipe->wait);
|
|
kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
|
|
do_wakeup = 0;
|
|
}
|
|
|
|
opipe->waiting_writers++;
|
|
pipe_wait(opipe);
|
|
opipe->waiting_writers--;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* No input buffers, do the usual checks for available
|
|
* writers and blocking and wait if necessary
|
|
*/
|
|
if (!ipipe->writers)
|
|
break;
|
|
if (!ipipe->waiting_writers) {
|
|
if (ret)
|
|
break;
|
|
}
|
|
/*
|
|
* pipe_wait() drops the ipipe mutex. To avoid deadlocks
|
|
* with another process, we can only safely do that if
|
|
* the ipipe lock is ordered last.
|
|
*/
|
|
if ((flags & SPLICE_F_NONBLOCK) || ipipe_first) {
|
|
if (!ret)
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
if (signal_pending(current)) {
|
|
if (!ret)
|
|
ret = -ERESTARTSYS;
|
|
break;
|
|
}
|
|
|
|
if (waitqueue_active(&ipipe->wait))
|
|
wake_up_interruptible_sync(&ipipe->wait);
|
|
kill_fasync(&ipipe->fasync_writers, SIGIO, POLL_OUT);
|
|
|
|
pipe_wait(ipipe);
|
|
}
|
|
|
|
mutex_unlock(&ipipe->inode->i_mutex);
|
|
mutex_unlock(&opipe->inode->i_mutex);
|
|
|
|
if (do_wakeup) {
|
|
smp_mb();
|
|
if (waitqueue_active(&opipe->wait))
|
|
wake_up_interruptible(&opipe->wait);
|
|
kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN);
|
|
}
|
|
|
|
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 = in->f_dentry->d_inode->i_pipe;
|
|
struct pipe_inode_info *opipe = out->f_dentry->d_inode->i_pipe;
|
|
|
|
/*
|
|
* Link ipipe to the two output pipes, consuming as we go along.
|
|
*/
|
|
if (ipipe && opipe)
|
|
return link_pipe(ipipe, opipe, len, flags);
|
|
|
|
return -EINVAL;
|
|
}
|
|
|
|
asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags)
|
|
{
|
|
struct file *in;
|
|
int error, fput_in;
|
|
|
|
if (unlikely(!len))
|
|
return 0;
|
|
|
|
error = -EBADF;
|
|
in = fget_light(fdin, &fput_in);
|
|
if (in) {
|
|
if (in->f_mode & FMODE_READ) {
|
|
int fput_out;
|
|
struct file *out = fget_light(fdout, &fput_out);
|
|
|
|
if (out) {
|
|
if (out->f_mode & FMODE_WRITE)
|
|
error = do_tee(in, out, len, flags);
|
|
fput_light(out, fput_out);
|
|
}
|
|
}
|
|
fput_light(in, fput_in);
|
|
}
|
|
|
|
return error;
|
|
}
|