[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/fs/splice.c b/ap/os/linux/linux-3.4.x/fs/splice.c
new file mode 100644
index 0000000..67c5210
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/fs/splice.c
@@ -0,0 +1,2054 @@
+/*
+ * "splice": joining two ropes together by interweaving their strands.
+ *
+ * This is the "extended pipe" functionality, where a pipe is used as
+ * an arbitrary in-memory buffer. Think of a pipe as a small kernel
+ * buffer that you can use to transfer data from one end to the other.
+ *
+ * The traditional unix read/write is extended with a "splice()" operation
+ * that transfers data buffers to or from a pipe buffer.
+ *
+ * Named by Larry McVoy, original implementation from Linus, extended by
+ * Jens to support splicing to files, network, direct splicing, etc and
+ * fixing lots of bugs.
+ *
+ * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
+ * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
+ * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
+ *
+ */
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/pagemap.h>
+#include <linux/splice.h>
+#include <linux/memcontrol.h>
+#include <linux/mm_inline.h>
+#include <linux/swap.h>
+#include <linux/writeback.h>
+#include <linux/export.h>
+#include <linux/syscalls.h>
+#include <linux/uio.h>
+#include <linux/security.h>
+#include <linux/gfp.h>
+#include <linux/socket.h>
+
+/*
+ * Attempt to steal a page from a pipe buffer. This should perhaps go into
+ * a vm helper function, it's already simplified quite a bit by the
+ * addition of remove_mapping(). If success is returned, the caller may
+ * attempt to reuse this page for another destination.
+ */
+static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ struct page *page = buf->page;
+ struct address_space *mapping;
+
+ lock_page(page);
+
+ mapping = page_mapping(page);
+ if (mapping) {
+ WARN_ON(!PageUptodate(page));
+
+ /*
+ * At least for ext2 with nobh option, we need to wait on
+ * writeback completing on this page, since we'll remove it
+ * from the pagecache. Otherwise truncate wont wait on the
+ * page, allowing the disk blocks to be reused by someone else
+ * before we actually wrote our data to them. fs corruption
+ * ensues.
+ */
+ wait_on_page_writeback(page);
+
+ if (page_has_private(page) &&
+ !try_to_release_page(page, GFP_KERNEL))
+ goto out_unlock;
+
+ /*
+ * If we succeeded in removing the mapping, set LRU flag
+ * and return good.
+ */
+ if (remove_mapping(mapping, page)) {
+ buf->flags |= PIPE_BUF_FLAG_LRU;
+ return 0;
+ }
+ }
+
+ /*
+ * Raced with truncate or failed to remove page from current
+ * address space, unlock and return failure.
+ */
+out_unlock:
+ unlock_page(page);
+ return 1;
+}
+
+static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ page_cache_release(buf->page);
+ buf->flags &= ~PIPE_BUF_FLAG_LRU;
+}
+
+/*
+ * Check whether the contents of buf is OK to access. Since the content
+ * is a page cache page, IO may be in flight.
+ */
+static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ struct page *page = buf->page;
+ int err;
+
+ if (!PageUptodate(page)) {
+ lock_page(page);
+
+ /*
+ * Page got truncated/unhashed. This will cause a 0-byte
+ * splice, if this is the first page.
+ */
+ if (!page->mapping) {
+ err = -ENODATA;
+ goto error;
+ }
+
+ /*
+ * Uh oh, read-error from disk.
+ */
+ if (!PageUptodate(page)) {
+ err = -EIO;
+ goto error;
+ }
+
+ /*
+ * Page is ok afterall, we are done.
+ */
+ unlock_page(page);
+ }
+
+ return 0;
+error:
+ unlock_page(page);
+ return err;
+}
+
+const struct pipe_buf_operations page_cache_pipe_buf_ops = {
+ .can_merge = 0,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .confirm = page_cache_pipe_buf_confirm,
+ .release = page_cache_pipe_buf_release,
+ .steal = page_cache_pipe_buf_steal,
+ .get = generic_pipe_buf_get,
+};
+
+static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf)
+{
+ if (!(buf->flags & PIPE_BUF_FLAG_GIFT))
+ return 1;
+
+ buf->flags |= PIPE_BUF_FLAG_LRU;
+ return generic_pipe_buf_steal(pipe, buf);
+}
+
+static const struct pipe_buf_operations user_page_pipe_buf_ops = {
+ .can_merge = 0,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .confirm = generic_pipe_buf_confirm,
+ .release = page_cache_pipe_buf_release,
+ .steal = user_page_pipe_buf_steal,
+ .get = generic_pipe_buf_get,
+};
+
+static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
+{
+ smp_mb();
+ if (waitqueue_active(&pipe->wait))
+ wake_up_interruptible(&pipe->wait);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+}
+
+/**
+ * splice_to_pipe - fill passed data into a pipe
+ * @pipe: pipe to fill
+ * @spd: data to fill
+ *
+ * Description:
+ * @spd contains a map of pages and len/offset tuples, along with
+ * the struct pipe_buf_operations associated with these pages. This
+ * function will link that data to the pipe.
+ *
+ */
+ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
+ struct splice_pipe_desc *spd)
+{
+ unsigned int spd_pages = spd->nr_pages;
+ int ret, do_wakeup, page_nr;
+
+ ret = 0;
+ do_wakeup = 0;
+ page_nr = 0;
+
+ pipe_lock(pipe);
+
+ for (;;) {
+ if (!pipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ if (!ret)
+ ret = -EPIPE;
+ break;
+ }
+
+ if (pipe->nrbufs < pipe->buffers) {
+ int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
+ struct pipe_buffer *buf = pipe->bufs + newbuf;
+
+ buf->page = spd->pages[page_nr];
+ buf->offset = spd->partial[page_nr].offset;
+ buf->len = spd->partial[page_nr].len;
+ buf->private = spd->partial[page_nr].private;
+ buf->ops = spd->ops;
+ if (spd->flags & SPLICE_F_GIFT)
+ buf->flags |= PIPE_BUF_FLAG_GIFT;
+
+ pipe->nrbufs++;
+ page_nr++;
+ ret += buf->len;
+
+ if (pipe->inode)
+ do_wakeup = 1;
+
+ if (!--spd->nr_pages)
+ break;
+ if (pipe->nrbufs < pipe->buffers)
+ continue;
+
+ break;
+ }
+
+ if (spd->flags & SPLICE_F_NONBLOCK) {
+ if (!ret)
+ ret = -EAGAIN;
+ break;
+ }
+
+ if (signal_pending(current)) {
+ if (!ret)
+ ret = -ERESTARTSYS;
+ break;
+ }
+
+ if (do_wakeup) {
+ smp_mb();
+ if (waitqueue_active(&pipe->wait))
+ wake_up_interruptible_sync(&pipe->wait);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+ do_wakeup = 0;
+ }
+
+ pipe->waiting_writers++;
+ pipe_wait(pipe);
+ pipe->waiting_writers--;
+ }
+
+ pipe_unlock(pipe);
+
+ if (do_wakeup)
+ wakeup_pipe_readers(pipe);
+
+ while (page_nr < spd_pages)
+ spd->spd_release(spd, page_nr++);
+
+ return ret;
+}
+
+void spd_release_page(struct splice_pipe_desc *spd, unsigned int i)
+{
+ page_cache_release(spd->pages[i]);
+}
+
+/*
+ * Check if we need to grow the arrays holding pages and partial page
+ * descriptions.
+ */
+int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
+{
+ unsigned int buffers = ACCESS_ONCE(pipe->buffers);
+
+ spd->nr_pages_max = buffers;
+ if (buffers <= PIPE_DEF_BUFFERS)
+ return 0;
+
+ spd->pages = kmalloc(buffers * sizeof(struct page *), GFP_KERNEL);
+ spd->partial = kmalloc(buffers * sizeof(struct partial_page), GFP_KERNEL);
+
+ if (spd->pages && spd->partial)
+ return 0;
+
+ kfree(spd->pages);
+ kfree(spd->partial);
+ return -ENOMEM;
+}
+
+void splice_shrink_spd(struct splice_pipe_desc *spd)
+{
+ if (spd->nr_pages_max <= PIPE_DEF_BUFFERS)
+ return;
+
+ kfree(spd->pages);
+ kfree(spd->partial);
+}
+
+static int
+__generic_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
+{
+ struct address_space *mapping = in->f_mapping;
+ unsigned int loff, nr_pages, req_pages;
+ struct page *pages[PIPE_DEF_BUFFERS];
+ struct partial_page partial[PIPE_DEF_BUFFERS];
+ struct page *page;
+ pgoff_t index, end_index;
+ loff_t isize;
+ int error, page_nr;
+ struct splice_pipe_desc spd = {
+ .pages = pages,
+ .partial = partial,
+ .nr_pages_max = PIPE_DEF_BUFFERS,
+ .flags = flags,
+ .ops = &page_cache_pipe_buf_ops,
+ .spd_release = spd_release_page,
+ };
+
+ if (splice_grow_spd(pipe, &spd))
+ return -ENOMEM;
+
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ loff = *ppos & ~PAGE_CACHE_MASK;
+ req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ nr_pages = min(req_pages, spd.nr_pages_max);
+
+ /*
+ * Lookup the (hopefully) full range of pages we need.
+ */
+ spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages);
+ index += spd.nr_pages;
+
+ /*
+ * If find_get_pages_contig() returned fewer pages than we needed,
+ * readahead/allocate the rest and fill in the holes.
+ */
+ if (spd.nr_pages < nr_pages)
+ page_cache_sync_readahead(mapping, &in->f_ra, in,
+ index, req_pages - spd.nr_pages);
+
+ error = 0;
+ while (spd.nr_pages < nr_pages) {
+ /*
+ * Page could be there, find_get_pages_contig() breaks on
+ * the first hole.
+ */
+ page = find_get_page(mapping, index);
+ if (!page) {
+ /*
+ * page didn't exist, allocate one.
+ */
+ page = page_cache_alloc_cold(mapping);
+ if (!page)
+ break;
+
+ error = add_to_page_cache_lru(page, mapping, index,
+ GFP_KERNEL);
+ if (unlikely(error)) {
+ page_cache_release(page);
+ if (error == -EEXIST)
+ continue;
+ break;
+ }
+ /*
+ * add_to_page_cache() locks the page, unlock it
+ * to avoid convoluting the logic below even more.
+ */
+ unlock_page(page);
+ }
+
+ spd.pages[spd.nr_pages++] = page;
+ index++;
+ }
+
+ /*
+ * Now loop over the map and see if we need to start IO on any
+ * pages, fill in the partial map, etc.
+ */
+ index = *ppos >> PAGE_CACHE_SHIFT;
+ nr_pages = spd.nr_pages;
+ spd.nr_pages = 0;
+ for (page_nr = 0; page_nr < nr_pages; page_nr++) {
+ unsigned int this_len;
+
+ if (!len)
+ break;
+
+ /*
+ * this_len is the max we'll use from this page
+ */
+ this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
+ page = spd.pages[page_nr];
+
+ if (PageReadahead(page))
+ page_cache_async_readahead(mapping, &in->f_ra, in,
+ page, index, req_pages - page_nr);
+
+ /*
+ * If the page isn't uptodate, we may need to start io on it
+ */
+ if (!PageUptodate(page)) {
+ lock_page(page);
+
+ /*
+ * Page was truncated, or invalidated by the
+ * filesystem. Redo the find/create, but this time the
+ * page is kept locked, so there's no chance of another
+ * race with truncate/invalidate.
+ */
+ if (!page->mapping) {
+ unlock_page(page);
+ page = find_or_create_page(mapping, index,
+ mapping_gfp_mask(mapping));
+
+ if (!page) {
+ error = -ENOMEM;
+ break;
+ }
+ page_cache_release(spd.pages[page_nr]);
+ spd.pages[page_nr] = page;
+ }
+ /*
+ * page was already under io and is now done, great
+ */
+ if (PageUptodate(page)) {
+ unlock_page(page);
+ goto fill_it;
+ }
+
+ /*
+ * need to read in the page
+ */
+ error = mapping->a_ops->readpage(in, page);
+ if (unlikely(error)) {
+ /*
+ * We really should re-lookup the page here,
+ * but it complicates things a lot. Instead
+ * lets just do what we already stored, and
+ * we'll get it the next time we are called.
+ */
+ if (error == AOP_TRUNCATED_PAGE)
+ error = 0;
+
+ break;
+ }
+ }
+fill_it:
+ /*
+ * i_size must be checked after PageUptodate.
+ */
+ isize = i_size_read(mapping->host);
+ end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+ if (unlikely(!isize || index > end_index))
+ break;
+
+ /*
+ * if this is the last page, see if we need to shrink
+ * the length and stop
+ */
+ if (end_index == index) {
+ unsigned int plen;
+
+ /*
+ * max good bytes in this page
+ */
+ plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
+ if (plen <= loff)
+ break;
+
+ /*
+ * force quit after adding this page
+ */
+ this_len = min(this_len, plen - loff);
+ len = this_len;
+ }
+
+ spd.partial[page_nr].offset = loff;
+ spd.partial[page_nr].len = this_len;
+ len -= this_len;
+ loff = 0;
+ spd.nr_pages++;
+ index++;
+ }
+
+ /*
+ * Release any pages at the end, if we quit early. 'page_nr' is how far
+ * we got, 'nr_pages' is how many pages are in the map.
+ */
+ while (page_nr < nr_pages)
+ page_cache_release(spd.pages[page_nr++]);
+ in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT;
+
+ if (spd.nr_pages)
+ error = splice_to_pipe(pipe, &spd);
+
+ splice_shrink_spd(&spd);
+ return error;
+}
+
+/**
+ * generic_file_splice_read - splice data from file to a pipe
+ * @in: file to splice from
+ * @ppos: position in @in
+ * @pipe: pipe to splice to
+ * @len: number of bytes to splice
+ * @flags: splice modifier flags
+ *
+ * Description:
+ * Will read pages from given file and fill them into a pipe. Can be
+ * used as long as the address_space operations for the source implements
+ * a readpage() hook.
+ *
+ */
+ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
+{
+ loff_t isize, left;
+ int ret;
+
+ isize = i_size_read(in->f_mapping->host);
+ if (unlikely(*ppos >= isize))
+ return 0;
+
+ left = isize - *ppos;
+ if (unlikely(left < len))
+ len = left;
+
+ ret = __generic_file_splice_read(in, ppos, pipe, len, flags);
+ if (ret > 0) {
+ *ppos += ret;
+ file_accessed(in);
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL(generic_file_splice_read);
+
+static const struct pipe_buf_operations default_pipe_buf_ops = {
+ .can_merge = 0,
+ .map = generic_pipe_buf_map,
+ .unmap = generic_pipe_buf_unmap,
+ .confirm = generic_pipe_buf_confirm,
+ .release = generic_pipe_buf_release,
+ .steal = generic_pipe_buf_steal,
+ .get = generic_pipe_buf_get,
+};
+
+static ssize_t kernel_readv(struct file *file, const struct iovec *vec,
+ unsigned long vlen, loff_t offset)
+{
+ mm_segment_t old_fs;
+ loff_t pos = offset;
+ ssize_t res;
+
+ old_fs = get_fs();
+ set_fs(get_ds());
+ /* The cast to a user pointer is valid due to the set_fs() */
+ res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos);
+ set_fs(old_fs);
+
+ return res;
+}
+
+static ssize_t kernel_write(struct file *file, const char *buf, size_t count,
+ loff_t pos)
+{
+ mm_segment_t old_fs;
+ ssize_t res;
+
+ old_fs = get_fs();
+ set_fs(get_ds());
+ /* The cast to a user pointer is valid due to the set_fs() */
+ res = vfs_write(file, (const char __user *)buf, count, &pos);
+ set_fs(old_fs);
+
+ return res;
+}
+
+ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
+{
+ unsigned int nr_pages;
+ unsigned int nr_freed;
+ size_t offset;
+ struct page *pages[PIPE_DEF_BUFFERS];
+ struct partial_page partial[PIPE_DEF_BUFFERS];
+ struct iovec *vec, __vec[PIPE_DEF_BUFFERS];
+ ssize_t res;
+ size_t this_len;
+ int error;
+ int i;
+ struct splice_pipe_desc spd = {
+ .pages = pages,
+ .partial = partial,
+ .nr_pages_max = PIPE_DEF_BUFFERS,
+ .flags = flags,
+ .ops = &default_pipe_buf_ops,
+ .spd_release = spd_release_page,
+ };
+
+ if (splice_grow_spd(pipe, &spd))
+ return -ENOMEM;
+
+ res = -ENOMEM;
+ vec = __vec;
+ if (spd.nr_pages_max > PIPE_DEF_BUFFERS) {
+ vec = kmalloc(spd.nr_pages_max * sizeof(struct iovec), GFP_KERNEL);
+ if (!vec)
+ goto shrink_ret;
+ }
+
+ offset = *ppos & ~PAGE_CACHE_MASK;
+ nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
+ for (i = 0; i < nr_pages && i < spd.nr_pages_max && len; i++) {
+ struct page *page;
+
+ page = alloc_page(GFP_USER);
+ error = -ENOMEM;
+ if (!page)
+ goto err;
+
+ this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset);
+ vec[i].iov_base = (void __user *) page_address(page);
+ vec[i].iov_len = this_len;
+ spd.pages[i] = page;
+ spd.nr_pages++;
+ len -= this_len;
+ offset = 0;
+ }
+
+ res = kernel_readv(in, vec, spd.nr_pages, *ppos);
+ if (res < 0) {
+ error = res;
+ goto err;
+ }
+
+ error = 0;
+ if (!res)
+ goto err;
+
+ nr_freed = 0;
+ for (i = 0; i < spd.nr_pages; i++) {
+ this_len = min_t(size_t, vec[i].iov_len, res);
+ spd.partial[i].offset = 0;
+ spd.partial[i].len = this_len;
+ if (!this_len) {
+ __free_page(spd.pages[i]);
+ spd.pages[i] = NULL;
+ nr_freed++;
+ }
+ res -= this_len;
+ }
+ spd.nr_pages -= nr_freed;
+
+ res = splice_to_pipe(pipe, &spd);
+ if (res > 0)
+ *ppos += res;
+
+shrink_ret:
+ if (vec != __vec)
+ kfree(vec);
+ splice_shrink_spd(&spd);
+ return res;
+
+err:
+ for (i = 0; i < spd.nr_pages; i++)
+ __free_page(spd.pages[i]);
+
+ res = error;
+ goto shrink_ret;
+}
+EXPORT_SYMBOL(default_file_splice_read);
+
+/*
+ * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
+ * using sendpage(). Return the number of bytes sent.
+ */
+static int pipe_to_sendpage(struct pipe_inode_info *pipe,
+ struct pipe_buffer *buf, struct splice_desc *sd)
+{
+ struct file *file = sd->u.file;
+ loff_t pos = sd->pos;
+ int more;
+
+ if (!likely(file->f_op && file->f_op->sendpage))
+ return -EINVAL;
+
+ more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
+
+ if (sd->len < sd->total_len && pipe->nrbufs > 1)
+ more |= MSG_SENDPAGE_NOTLAST;
+
+ return file->f_op->sendpage(file, buf->page, buf->offset,
+ sd->len, &pos, more);
+}
+
+/*
+ * 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.
+ */
+int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+ struct splice_desc *sd)
+{
+ struct file *file = sd->u.file;
+ struct address_space *mapping = file->f_mapping;
+ unsigned int offset, this_len;
+ struct page *page;
+ void *fsdata;
+ int ret;
+
+ offset = sd->pos & ~PAGE_CACHE_MASK;
+
+ this_len = sd->len;
+ if (this_len + offset > PAGE_CACHE_SIZE)
+ this_len = PAGE_CACHE_SIZE - offset;
+
+ ret = pagecache_write_begin(file, mapping, sd->pos, this_len,
+ AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata);
+ if (unlikely(ret))
+ goto out;
+
+ if (buf->page != page) {
+ char *src = buf->ops->map(pipe, buf, 1);
+ char *dst = kmap_atomic(page);
+
+ memcpy(dst + offset, src + buf->offset, this_len);
+ flush_dcache_page(page);
+ kunmap_atomic(dst);
+ buf->ops->unmap(pipe, buf, src);
+ }
+ ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len,
+ page, fsdata);
+out:
+ return ret;
+}
+EXPORT_SYMBOL(pipe_to_file);
+
+static void wakeup_pipe_writers(struct pipe_inode_info *pipe)
+{
+ smp_mb();
+ if (waitqueue_active(&pipe->wait))
+ wake_up_interruptible(&pipe->wait);
+ kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
+}
+
+/**
+ * splice_from_pipe_feed - feed available data from a pipe to a file
+ * @pipe: pipe to splice from
+ * @sd: information to @actor
+ * @actor: handler that splices the data
+ *
+ * Description:
+ * This function loops over the pipe and calls @actor to do the
+ * actual moving of a single struct pipe_buffer to the desired
+ * destination. It returns when there's no more buffers left in
+ * the pipe or if the requested number of bytes (@sd->total_len)
+ * have been copied. It returns a positive number (one) if the
+ * pipe needs to be filled with more data, zero if the required
+ * number of bytes have been copied and -errno on error.
+ *
+ * This, together with splice_from_pipe_{begin,end,next}, may be
+ * used to implement the functionality of __splice_from_pipe() when
+ * locking is required around copying the pipe buffers to the
+ * destination.
+ */
+int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd,
+ splice_actor *actor)
+{
+ int ret;
+
+ while (pipe->nrbufs) {
+ struct pipe_buffer *buf = pipe->bufs + pipe->curbuf;
+ const struct pipe_buf_operations *ops = buf->ops;
+
+ sd->len = buf->len;
+ if (sd->len > sd->total_len)
+ sd->len = sd->total_len;
+
+ ret = buf->ops->confirm(pipe, buf);
+ if (unlikely(ret)) {
+ if (ret == -ENODATA)
+ ret = 0;
+ return ret;
+ }
+
+ ret = actor(pipe, buf, sd);
+ if (ret <= 0)
+ return ret;
+
+ buf->offset += ret;
+ buf->len -= ret;
+
+ sd->num_spliced += ret;
+ sd->len -= ret;
+ sd->pos += ret;
+ sd->total_len -= ret;
+
+ if (!buf->len) {
+ buf->ops = NULL;
+ ops->release(pipe, buf);
+ pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1);
+ pipe->nrbufs--;
+ if (pipe->inode)
+ sd->need_wakeup = true;
+ }
+
+ if (!sd->total_len)
+ return 0;
+ }
+
+ return 1;
+}
+EXPORT_SYMBOL(splice_from_pipe_feed);
+
+/**
+ * splice_from_pipe_next - wait for some data to splice from
+ * @pipe: pipe to splice from
+ * @sd: information about the splice operation
+ *
+ * Description:
+ * This function will wait for some data and return a positive
+ * value (one) if pipe buffers are available. It will return zero
+ * or -errno if no more data needs to be spliced.
+ */
+int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd)
+{
+ while (!pipe->nrbufs) {
+ if (!pipe->writers)
+ return 0;
+
+ if (!pipe->waiting_writers && sd->num_spliced)
+ return 0;
+
+ if (sd->flags & SPLICE_F_NONBLOCK)
+ return -EAGAIN;
+
+ if (signal_pending(current))
+ return -ERESTARTSYS;
+
+ if (sd->need_wakeup) {
+ wakeup_pipe_writers(pipe);
+ sd->need_wakeup = false;
+ }
+
+ pipe_wait(pipe);
+ }
+
+ return 1;
+}
+EXPORT_SYMBOL(splice_from_pipe_next);
+
+/**
+ * splice_from_pipe_begin - start splicing from pipe
+ * @sd: information about the splice operation
+ *
+ * Description:
+ * This function should be called before a loop containing
+ * splice_from_pipe_next() and splice_from_pipe_feed() to
+ * initialize the necessary fields of @sd.
+ */
+void splice_from_pipe_begin(struct splice_desc *sd)
+{
+ sd->num_spliced = 0;
+ sd->need_wakeup = false;
+}
+EXPORT_SYMBOL(splice_from_pipe_begin);
+
+/**
+ * splice_from_pipe_end - finish splicing from pipe
+ * @pipe: pipe to splice from
+ * @sd: information about the splice operation
+ *
+ * Description:
+ * This function will wake up pipe writers if necessary. It should
+ * be called after a loop containing splice_from_pipe_next() and
+ * splice_from_pipe_feed().
+ */
+void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd)
+{
+ if (sd->need_wakeup)
+ wakeup_pipe_writers(pipe);
+}
+EXPORT_SYMBOL(splice_from_pipe_end);
+
+/**
+ * __splice_from_pipe - splice data from a pipe to given actor
+ * @pipe: pipe to splice from
+ * @sd: information to @actor
+ * @actor: handler that splices the data
+ *
+ * Description:
+ * This function does little more than loop over the pipe and call
+ * @actor to do the actual moving of a single struct pipe_buffer to
+ * the desired destination. See pipe_to_file, pipe_to_sendpage, or
+ * pipe_to_user.
+ *
+ */
+ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd,
+ splice_actor *actor)
+{
+ int ret;
+
+ splice_from_pipe_begin(sd);
+ do {
+ ret = splice_from_pipe_next(pipe, sd);
+ if (ret > 0)
+ ret = splice_from_pipe_feed(pipe, sd, actor);
+ } while (ret > 0);
+ splice_from_pipe_end(pipe, sd);
+
+ return sd->num_spliced ? sd->num_spliced : ret;
+}
+EXPORT_SYMBOL(__splice_from_pipe);
+
+/**
+ * splice_from_pipe - splice data from a pipe to a file
+ * @pipe: pipe to splice from
+ * @out: file to splice to
+ * @ppos: position in @out
+ * @len: how many bytes to splice
+ * @flags: splice modifier flags
+ * @actor: handler that splices the data
+ *
+ * Description:
+ * See __splice_from_pipe. This function locks the pipe inode,
+ * otherwise it's identical to __splice_from_pipe().
+ *
+ */
+ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags,
+ splice_actor *actor)
+{
+ ssize_t ret;
+ struct splice_desc sd = {
+ .total_len = len,
+ .flags = flags,
+ .pos = *ppos,
+ .u.file = out,
+ };
+
+ pipe_lock(pipe);
+ ret = __splice_from_pipe(pipe, &sd, actor);
+ pipe_unlock(pipe);
+
+ return ret;
+}
+
+/**
+ * generic_file_splice_write - splice data from a pipe to a file
+ * @pipe: pipe info
+ * @out: file to write to
+ * @ppos: position in @out
+ * @len: number of bytes to splice
+ * @flags: splice modifier flags
+ *
+ * Description:
+ * Will either move or copy pages (determined by @flags options) from
+ * the given pipe inode to the given file.
+ *
+ */
+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;
+ struct inode *inode = mapping->host;
+ struct splice_desc sd = {
+ .flags = flags,
+ .u.file = out,
+ };
+ ssize_t ret;
+
+ ret = generic_write_checks(out, ppos, &len, S_ISBLK(inode->i_mode));
+ if (ret)
+ return ret;
+ sd.total_len = len;
+ sd.pos = *ppos;
+
+ pipe_lock(pipe);
+
+ splice_from_pipe_begin(&sd);
+ do {
+ ret = splice_from_pipe_next(pipe, &sd);
+ if (ret <= 0)
+ break;
+
+ mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
+ ret = file_remove_suid(out);
+ if (!ret) {
+ file_update_time(out);
+ ret = splice_from_pipe_feed(pipe, &sd, pipe_to_file);
+ }
+ mutex_unlock(&inode->i_mutex);
+ } while (ret > 0);
+ splice_from_pipe_end(pipe, &sd);
+
+ pipe_unlock(pipe);
+
+ if (sd.num_spliced)
+ ret = sd.num_spliced;
+
+ if (ret > 0) {
+ unsigned long nr_pages;
+ int err;
+
+ nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
+ err = generic_write_sync(out, *ppos, ret);
+ if (err)
+ ret = err;
+ else
+ *ppos += ret;
+ balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
+ }
+
+ return ret;
+}
+
+EXPORT_SYMBOL(generic_file_splice_write);
+
+static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+ struct splice_desc *sd)
+{
+ int ret;
+ void *data;
+
+ data = buf->ops->map(pipe, buf, 0);
+ ret = kernel_write(sd->u.file, data + buf->offset, sd->len, sd->pos);
+ buf->ops->unmap(pipe, buf, data);
+
+ return ret;
+}
+
+static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
+ struct file *out, loff_t *ppos,
+ size_t len, unsigned int flags)
+{
+ ssize_t ret;
+
+ ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
+ if (ret > 0)
+ *ppos += ret;
+
+ return ret;
+}
+
+/**
+ * generic_splice_sendpage - splice data from a pipe to a socket
+ * @pipe: pipe to splice from
+ * @out: socket to write to
+ * @ppos: position in @out
+ * @len: number of bytes to splice
+ * @flags: splice modifier flags
+ *
+ * Description:
+ * Will send @len bytes from the pipe to a network socket. No data copying
+ * is involved.
+ *
+ */
+ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags)
+{
+ return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage);
+}
+
+EXPORT_SYMBOL(generic_splice_sendpage);
+
+/*
+ * Attempt to initiate a splice from pipe to file.
+ */
+static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
+ loff_t *ppos, size_t len, unsigned int flags)
+{
+ ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
+ loff_t *, size_t, unsigned int);
+ int ret;
+
+ if (unlikely(!(out->f_mode & FMODE_WRITE)))
+ return -EBADF;
+
+ if (unlikely(out->f_flags & O_APPEND))
+ return -EINVAL;
+
+ ret = rw_verify_area(WRITE, out, ppos, len);
+ if (unlikely(ret < 0))
+ return ret;
+
+ if (out->f_op && out->f_op->splice_write)
+ splice_write = out->f_op->splice_write;
+ else
+ splice_write = default_file_splice_write;
+
+ return splice_write(pipe, out, ppos, len, flags);
+}
+
+/*
+ * Attempt to initiate a splice from a file to a pipe.
+ */
+static long do_splice_to(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
+{
+ ssize_t (*splice_read)(struct file *, loff_t *,
+ struct pipe_inode_info *, size_t, unsigned int);
+ int ret;
+
+ if (unlikely(!(in->f_mode & FMODE_READ)))
+ return -EBADF;
+
+ ret = rw_verify_area(READ, in, ppos, len);
+ if (unlikely(ret < 0))
+ return ret;
+
+ if (in->f_op && in->f_op->splice_read)
+ splice_read = in->f_op->splice_read;
+ else
+ splice_read = default_file_splice_read;
+
+ return splice_read(in, ppos, pipe, len, flags);
+}
+
+/**
+ * splice_direct_to_actor - splices data directly between two non-pipes
+ * @in: file to splice from
+ * @sd: actor information on where to splice to
+ * @actor: handles the data splicing
+ *
+ * Description:
+ * This is a special case helper to splice directly between two
+ * points, without requiring an explicit pipe. Internally an allocated
+ * pipe is cached in the process, and reused during the lifetime of
+ * that process.
+ *
+ */
+ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
+ splice_direct_actor *actor)
+{
+ struct pipe_inode_info *pipe;
+ long ret, bytes;
+ umode_t i_mode;
+ size_t len;
+ int i, flags;
+
+ /*
+ * We require the input being a regular file, as we don't want to
+ * randomly drop data for eg socket -> socket splicing. Use the
+ * piped splicing for that!
+ */
+ i_mode = in->f_path.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;
+ len = sd->total_len;
+ flags = sd->flags;
+
+ /*
+ * Don't block on output, we have to drain the direct pipe.
+ */
+ sd->flags &= ~SPLICE_F_NONBLOCK;
+
+ while (len) {
+ size_t read_len;
+ loff_t pos = sd->pos, prev_pos = pos;
+
+ ret = do_splice_to(in, &pos, pipe, len, flags);
+ if (unlikely(ret <= 0))
+ goto out_release;
+
+ read_len = ret;
+ sd->total_len = read_len;
+
+ /*
+ * NOTE: nonblocking mode only applies to the input. We
+ * must not do the output in nonblocking mode as then we
+ * could get stuck data in the internal pipe:
+ */
+ ret = actor(pipe, sd);
+ if (unlikely(ret <= 0)) {
+ sd->pos = prev_pos;
+ goto out_release;
+ }
+
+ bytes += ret;
+ len -= ret;
+ sd->pos = pos;
+
+ if (ret < read_len) {
+ sd->pos = prev_pos + ret;
+ goto out_release;
+ }
+ }
+
+done:
+ pipe->nrbufs = pipe->curbuf = 0;
+ file_accessed(in);
+ return bytes;
+
+out_release:
+ /*
+ * If we did an incomplete transfer we must release
+ * the pipe buffers in question:
+ */
+ for (i = 0; i < pipe->buffers; i++) {
+ struct pipe_buffer *buf = pipe->bufs + i;
+
+ if (buf->ops) {
+ buf->ops->release(pipe, buf);
+ buf->ops = NULL;
+ }
+ }
+
+ if (!bytes)
+ bytes = ret;
+
+ goto done;
+}
+EXPORT_SYMBOL(splice_direct_to_actor);
+
+static int direct_splice_actor(struct pipe_inode_info *pipe,
+ struct splice_desc *sd)
+{
+ struct file *file = sd->u.file;
+
+ return do_splice_from(pipe, file, &file->f_pos, sd->total_len,
+ sd->flags);
+}
+
+/**
+ * do_splice_direct - splices data directly between two files
+ * @in: file to splice from
+ * @ppos: input file offset
+ * @out: file to splice to
+ * @len: number of bytes to splice
+ * @flags: splice modifier flags
+ *
+ * Description:
+ * For use by do_sendfile(). splice can easily emulate sendfile, but
+ * doing it in the application would incur an extra system call
+ * (splice in + splice out, as compared to just sendfile()). So this helper
+ * can splice directly through a process-private pipe.
+ *
+ */
+long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
+ size_t len, unsigned int flags)
+{
+ struct splice_desc sd = {
+ .len = len,
+ .total_len = len,
+ .flags = flags,
+ .pos = *ppos,
+ .u.file = out,
+ };
+ long ret;
+
+ ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
+ if (ret > 0)
+ *ppos = sd.pos;
+
+ return ret;
+}
+
+static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
+ struct pipe_inode_info *opipe,
+ size_t len, unsigned int flags);
+
+/*
+ * Determine where to splice to/from.
+ */
+static long do_splice(struct file *in, loff_t __user *off_in,
+ struct file *out, loff_t __user *off_out,
+ size_t len, unsigned int flags)
+{
+ struct pipe_inode_info *ipipe;
+ struct pipe_inode_info *opipe;
+ loff_t offset, *off;
+ long ret;
+
+ ipipe = get_pipe_info(in);
+ opipe = get_pipe_info(out);
+
+ if (ipipe && opipe) {
+ if (off_in || off_out)
+ return -ESPIPE;
+
+ if (!(in->f_mode & FMODE_READ))
+ return -EBADF;
+
+ if (!(out->f_mode & FMODE_WRITE))
+ return -EBADF;
+
+ /* Splicing to self would be fun, but... */
+ if (ipipe == opipe)
+ return -EINVAL;
+
+ return splice_pipe_to_pipe(ipipe, opipe, len, flags);
+ }
+
+ if (ipipe) {
+ if (off_in)
+ return -ESPIPE;
+ if (off_out) {
+ if (!(out->f_mode & FMODE_PWRITE))
+ return -EINVAL;
+ if (copy_from_user(&offset, off_out, sizeof(loff_t)))
+ return -EFAULT;
+ off = &offset;
+ } else
+ off = &out->f_pos;
+
+ ret = do_splice_from(ipipe, out, off, len, flags);
+
+ if (off_out && copy_to_user(off_out, off, sizeof(loff_t)))
+ ret = -EFAULT;
+
+ return ret;
+ }
+
+ if (opipe) {
+ if (off_out)
+ return -ESPIPE;
+ if (off_in) {
+ if (!(in->f_mode & FMODE_PREAD))
+ return -EINVAL;
+ if (copy_from_user(&offset, off_in, sizeof(loff_t)))
+ return -EFAULT;
+ off = &offset;
+ } else
+ off = &in->f_pos;
+
+ ret = do_splice_to(in, off, opipe, 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,
+ unsigned int pipe_buffers)
+{
+ int buffers = 0, error = 0;
+
+ while (nr_vecs) {
+ unsigned long off, npages;
+ struct iovec entry;
+ void __user *base;
+ size_t len;
+ int i;
+
+ error = -EFAULT;
+ if (copy_from_user(&entry, iov, sizeof(entry)))
+ break;
+
+ base = entry.iov_base;
+ len = entry.iov_len;
+
+ /*
+ * Sanity check this iovec. 0 read succeeds.
+ */
+ error = 0;
+ if (unlikely(!len))
+ break;
+ error = -EFAULT;
+ if (!access_ok(VERIFY_READ, base, len))
+ break;
+
+ /*
+ * Get this base offset and number of pages, then map
+ * in the user pages.
+ */
+ off = (unsigned long) base & ~PAGE_MASK;
+
+ /*
+ * If asked for alignment, the offset must be zero and the
+ * length a multiple of the PAGE_SIZE.
+ */
+ error = -EINVAL;
+ if (aligned && (off || len & ~PAGE_MASK))
+ break;
+
+ npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ if (npages > pipe_buffers - buffers)
+ npages = pipe_buffers - buffers;
+
+ error = get_user_pages_fast((unsigned long)base, npages,
+ 0, &pages[buffers]);
+
+ if (unlikely(error <= 0))
+ break;
+
+ /*
+ * Fill this contiguous range into the partial page map.
+ */
+ for (i = 0; i < error; i++) {
+ const int plen = min_t(size_t, len, PAGE_SIZE - off);
+
+ partial[buffers].offset = off;
+ partial[buffers].len = plen;
+
+ off = 0;
+ len -= plen;
+ buffers++;
+ }
+
+ /*
+ * We didn't complete this iov, stop here since it probably
+ * means we have to move some of this into a pipe to
+ * be able to continue.
+ */
+ if (len)
+ break;
+
+ /*
+ * Don't continue if we mapped fewer pages than we asked for,
+ * or if we mapped the max number of pages that we have
+ * room for.
+ */
+ if (error < npages || buffers == pipe_buffers)
+ break;
+
+ nr_vecs--;
+ iov++;
+ }
+
+ if (buffers)
+ return buffers;
+
+ return error;
+}
+
+static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+ struct splice_desc *sd)
+{
+ char *src;
+ int ret;
+
+ /*
+ * See if we can use the atomic maps, by prefaulting in the
+ * pages and doing an atomic copy
+ */
+ if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) {
+ src = buf->ops->map(pipe, buf, 1);
+ ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset,
+ sd->len);
+ buf->ops->unmap(pipe, buf, src);
+ if (!ret) {
+ ret = sd->len;
+ goto out;
+ }
+ }
+
+ /*
+ * No dice, use slow non-atomic map and copy
+ */
+ src = buf->ops->map(pipe, buf, 0);
+
+ ret = sd->len;
+ if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len))
+ ret = -EFAULT;
+
+ buf->ops->unmap(pipe, buf, src);
+out:
+ if (ret > 0)
+ sd->u.userptr += ret;
+ return ret;
+}
+
+/*
+ * For lack of a better implementation, implement vmsplice() to userspace
+ * as a simple copy of the pipes pages to the user iov.
+ */
+static long vmsplice_to_user(struct file *file, const struct iovec __user *iov,
+ unsigned long nr_segs, unsigned int flags)
+{
+ struct pipe_inode_info *pipe;
+ struct splice_desc sd;
+ ssize_t size;
+ int error;
+ long ret;
+
+ pipe = get_pipe_info(file);
+ if (!pipe)
+ return -EBADF;
+
+ pipe_lock(pipe);
+
+ error = ret = 0;
+ while (nr_segs) {
+ void __user *base;
+ size_t len;
+
+ /*
+ * 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;
+ if (unlikely(!base)) {
+ error = -EFAULT;
+ break;
+ }
+
+ if (unlikely(!access_ok(VERIFY_WRITE, base, len))) {
+ error = -EFAULT;
+ break;
+ }
+
+ sd.len = 0;
+ sd.total_len = len;
+ sd.flags = flags;
+ sd.u.userptr = base;
+ sd.pos = 0;
+
+ size = __splice_from_pipe(pipe, &sd, pipe_to_user);
+ if (size < 0) {
+ if (!ret)
+ ret = size;
+
+ break;
+ }
+
+ ret += size;
+
+ if (size < len)
+ break;
+
+ nr_segs--;
+ iov++;
+ }
+
+ pipe_unlock(pipe);
+
+ if (!ret)
+ ret = error;
+
+ return ret;
+}
+
+/*
+ * vmsplice splices a user address range into a pipe. It can be thought of
+ * as splice-from-memory, where the regular splice is splice-from-file (or
+ * to file). In both cases the output is a pipe, naturally.
+ */
+static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov,
+ unsigned long nr_segs, unsigned int flags)
+{
+ struct pipe_inode_info *pipe;
+ struct page *pages[PIPE_DEF_BUFFERS];
+ struct partial_page partial[PIPE_DEF_BUFFERS];
+ struct splice_pipe_desc spd = {
+ .pages = pages,
+ .partial = partial,
+ .nr_pages_max = PIPE_DEF_BUFFERS,
+ .flags = flags,
+ .ops = &user_page_pipe_buf_ops,
+ .spd_release = spd_release_page,
+ };
+ long ret;
+
+ pipe = get_pipe_info(file);
+ if (!pipe)
+ return -EBADF;
+
+ if (splice_grow_spd(pipe, &spd))
+ return -ENOMEM;
+
+ spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
+ spd.partial, flags & SPLICE_F_GIFT,
+ spd.nr_pages_max);
+ if (spd.nr_pages <= 0)
+ ret = spd.nr_pages;
+ else
+ ret = splice_to_pipe(pipe, &spd);
+
+ splice_shrink_spd(&spd);
+ return ret;
+}
+
+/*
+ * Note that vmsplice only really supports true splicing _from_ user memory
+ * to a pipe, not the other way around. Splicing from user memory is a simple
+ * operation that can be supported without any funky alignment restrictions
+ * or nasty vm tricks. We simply map in the user memory and fill them into
+ * a pipe. The reverse isn't quite as easy, though. There are two possible
+ * solutions for that:
+ *
+ * - memcpy() the data internally, at which point we might as well just
+ * do a regular read() on the buffer anyway.
+ * - Lots of nasty vm tricks, that are neither fast nor flexible (it
+ * has restriction limitations on both ends of the pipe).
+ *
+ * Currently we punt and implement it as a normal copy, see pipe_to_user().
+ *
+ */
+SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, iov,
+ unsigned long, nr_segs, unsigned int, flags)
+{
+ struct file *file;
+ long error;
+ int fput;
+
+ if (unlikely(nr_segs > UIO_MAXIOV))
+ return -EINVAL;
+ else if (unlikely(!nr_segs))
+ return 0;
+
+ error = -EBADF;
+ file = fget_light(fd, &fput);
+ if (file) {
+ if (file->f_mode & FMODE_WRITE)
+ error = vmsplice_to_pipe(file, iov, nr_segs, flags);
+ else if (file->f_mode & FMODE_READ)
+ error = vmsplice_to_user(file, iov, nr_segs, flags);
+
+ fput_light(file, fput);
+ }
+
+ return error;
+}
+
+SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in,
+ int, fd_out, loff_t __user *, off_out,
+ size_t, len, unsigned int, flags)
+{
+ 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;
+}
+
+/*
+ * Make sure there's data to read. Wait for input if we can, otherwise
+ * return an appropriate error.
+ */
+static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
+{
+ int ret;
+
+ /*
+ * Check ->nrbufs without the inode lock first. This function
+ * is speculative anyways, so missing one is ok.
+ */
+ if (pipe->nrbufs)
+ return 0;
+
+ ret = 0;
+ pipe_lock(pipe);
+
+ while (!pipe->nrbufs) {
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ break;
+ }
+ if (!pipe->writers)
+ break;
+ if (!pipe->waiting_writers) {
+ if (flags & SPLICE_F_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
+ }
+ pipe_wait(pipe);
+ }
+
+ pipe_unlock(pipe);
+ return ret;
+}
+
+/*
+ * Make sure there's writeable room. Wait for room if we can, otherwise
+ * return an appropriate error.
+ */
+static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags)
+{
+ int ret;
+
+ /*
+ * Check ->nrbufs without the inode lock first. This function
+ * is speculative anyways, so missing one is ok.
+ */
+ if (pipe->nrbufs < pipe->buffers)
+ return 0;
+
+ ret = 0;
+ pipe_lock(pipe);
+
+ while (pipe->nrbufs >= pipe->buffers) {
+ if (!pipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ ret = -EPIPE;
+ break;
+ }
+ if (flags & SPLICE_F_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ break;
+ }
+ pipe->waiting_writers++;
+ pipe_wait(pipe);
+ pipe->waiting_writers--;
+ }
+
+ pipe_unlock(pipe);
+ return ret;
+}
+
+/*
+ * Splice contents of ipipe to opipe.
+ */
+static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe,
+ struct pipe_inode_info *opipe,
+ size_t len, unsigned int flags)
+{
+ struct pipe_buffer *ibuf, *obuf;
+ int ret = 0, nbuf;
+ bool input_wakeup = false;
+
+
+retry:
+ ret = ipipe_prep(ipipe, flags);
+ if (ret)
+ return ret;
+
+ ret = opipe_prep(opipe, flags);
+ if (ret)
+ return ret;
+
+ /*
+ * Potential ABBA deadlock, work around it by ordering lock
+ * grabbing by pipe info address. Otherwise two different processes
+ * could deadlock (one doing tee from A -> B, the other from B -> A).
+ */
+ pipe_double_lock(ipipe, opipe);
+
+ do {
+ if (!opipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ if (!ret)
+ ret = -EPIPE;
+ break;
+ }
+
+ if (!ipipe->nrbufs && !ipipe->writers)
+ break;
+
+ /*
+ * Cannot make any progress, because either the input
+ * pipe is empty or the output pipe is full.
+ */
+ if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) {
+ /* Already processed some buffers, break */
+ if (ret)
+ break;
+
+ if (flags & SPLICE_F_NONBLOCK) {
+ ret = -EAGAIN;
+ break;
+ }
+
+ /*
+ * We raced with another reader/writer and haven't
+ * managed to process any buffers. A zero return
+ * value means EOF, so retry instead.
+ */
+ pipe_unlock(ipipe);
+ pipe_unlock(opipe);
+ goto retry;
+ }
+
+ ibuf = ipipe->bufs + ipipe->curbuf;
+ nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
+ obuf = opipe->bufs + nbuf;
+
+ if (len >= ibuf->len) {
+ /*
+ * Simply move the whole buffer from ipipe to opipe
+ */
+ *obuf = *ibuf;
+ ibuf->ops = NULL;
+ opipe->nrbufs++;
+ ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1);
+ ipipe->nrbufs--;
+ input_wakeup = true;
+ } else {
+ /*
+ * Get a reference to this pipe buffer,
+ * so we can copy the contents over.
+ */
+ ibuf->ops->get(ipipe, ibuf);
+ *obuf = *ibuf;
+
+ /*
+ * Don't inherit the gift flag, we need to
+ * prevent multiple steals of this page.
+ */
+ obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
+
+ obuf->len = len;
+ opipe->nrbufs++;
+ ibuf->offset += obuf->len;
+ ibuf->len -= obuf->len;
+ }
+ ret += obuf->len;
+ len -= obuf->len;
+ } while (len);
+
+ pipe_unlock(ipipe);
+ pipe_unlock(opipe);
+
+ /*
+ * If we put data in the output pipe, wakeup any potential readers.
+ */
+ if (ret > 0)
+ wakeup_pipe_readers(opipe);
+
+ if (input_wakeup)
+ wakeup_pipe_writers(ipipe);
+
+ return ret;
+}
+
+/*
+ * Link contents of ipipe to opipe.
+ */
+static int link_pipe(struct pipe_inode_info *ipipe,
+ struct pipe_inode_info *opipe,
+ size_t len, unsigned int flags)
+{
+ struct pipe_buffer *ibuf, *obuf;
+ int ret = 0, i = 0, nbuf;
+
+ /*
+ * Potential ABBA deadlock, work around it by ordering lock
+ * grabbing by pipe info address. Otherwise two different processes
+ * could deadlock (one doing tee from A -> B, the other from B -> A).
+ */
+ pipe_double_lock(ipipe, opipe);
+
+ do {
+ if (!opipe->readers) {
+ send_sig(SIGPIPE, current, 0);
+ if (!ret)
+ ret = -EPIPE;
+ break;
+ }
+
+ /*
+ * If we have iterated all input buffers or ran out of
+ * output room, break.
+ */
+ if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers)
+ break;
+
+ ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1));
+ nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1);
+
+ /*
+ * Get a reference to this pipe buffer,
+ * so we can copy the contents over.
+ */
+ ibuf->ops->get(ipipe, ibuf);
+
+ obuf = opipe->bufs + nbuf;
+ *obuf = *ibuf;
+
+ /*
+ * Don't inherit the gift flag, we need to
+ * prevent multiple steals of this page.
+ */
+ obuf->flags &= ~PIPE_BUF_FLAG_GIFT;
+
+ if (obuf->len > len)
+ obuf->len = len;
+
+ opipe->nrbufs++;
+ ret += obuf->len;
+ len -= obuf->len;
+ i++;
+ } while (len);
+
+ /*
+ * return EAGAIN if we have the potential of some data in the
+ * future, otherwise just return 0
+ */
+ if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK))
+ ret = -EAGAIN;
+
+ pipe_unlock(ipipe);
+ pipe_unlock(opipe);
+
+ /*
+ * If we put data in the output pipe, wakeup any potential readers.
+ */
+ if (ret > 0)
+ wakeup_pipe_readers(opipe);
+
+ return ret;
+}
+
+/*
+ * This is a tee(1) implementation that works on pipes. It doesn't copy
+ * any data, it simply references the 'in' pages on the 'out' pipe.
+ * The 'flags' used are the SPLICE_F_* variants, currently the only
+ * applicable one is SPLICE_F_NONBLOCK.
+ */
+static long do_tee(struct file *in, struct file *out, size_t len,
+ unsigned int flags)
+{
+ struct pipe_inode_info *ipipe = get_pipe_info(in);
+ struct pipe_inode_info *opipe = get_pipe_info(out);
+ int ret = -EINVAL;
+
+ /*
+ * Duplicate the contents of ipipe to opipe without actually
+ * copying the data.
+ */
+ if (ipipe && opipe && ipipe != opipe) {
+ /*
+ * Keep going, unless we encounter an error. The ipipe/opipe
+ * ordering doesn't really matter.
+ */
+ ret = ipipe_prep(ipipe, flags);
+ if (!ret) {
+ ret = opipe_prep(opipe, flags);
+ if (!ret)
+ ret = link_pipe(ipipe, opipe, len, flags);
+ }
+ }
+
+ return ret;
+}
+
+SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags)
+{
+ struct 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;
+}