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1721 lines
39 KiB
1721 lines
39 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
|
* "splice": joining two ropes together by interweaving their strands. |
|
* |
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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 |
|
* 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 <[email protected]> |
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* Copyright (C) 2005-2006 Linus Torvalds <[email protected]> |
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* Copyright (C) 2006 Ingo Molnar <[email protected]> |
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* |
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*/ |
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#include <linux/bvec.h> |
|
#include <linux/fs.h> |
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#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> |
|
#include <linux/sched/signal.h> |
|
|
|
#include "internal.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 bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
|
struct pipe_buffer *buf) |
|
{ |
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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 |
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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 |
|
* 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 true; |
|
} |
|
} |
|
|
|
/* |
|
* Raced with truncate or failed to remove page from current |
|
* address space, unlock and return failure. |
|
*/ |
|
out_unlock: |
|
unlock_page(page); |
|
return false; |
|
} |
|
|
|
static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
|
struct pipe_buffer *buf) |
|
{ |
|
put_page(buf->page); |
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buf->flags &= ~PIPE_BUF_FLAG_LRU; |
|
} |
|
|
|
/* |
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* Check whether the contents of buf is OK to access. Since the content |
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* is a page cache page, IO may be in flight. |
|
*/ |
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static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
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struct pipe_buffer *buf) |
|
{ |
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struct page *page = buf->page; |
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int err; |
|
|
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if (!PageUptodate(page)) { |
|
lock_page(page); |
|
|
|
/* |
|
* Page got truncated/unhashed. This will cause a 0-byte |
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* 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); |
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return err; |
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} |
|
|
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const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
|
.confirm = page_cache_pipe_buf_confirm, |
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.release = page_cache_pipe_buf_release, |
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.try_steal = page_cache_pipe_buf_try_steal, |
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.get = generic_pipe_buf_get, |
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}; |
|
|
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static bool user_page_pipe_buf_try_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 false; |
|
|
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buf->flags |= PIPE_BUF_FLAG_LRU; |
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return generic_pipe_buf_try_steal(pipe, buf); |
|
} |
|
|
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static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
|
.release = page_cache_pipe_buf_release, |
|
.try_steal = user_page_pipe_buf_try_steal, |
|
.get = generic_pipe_buf_get, |
|
}; |
|
|
|
static void wakeup_pipe_readers(struct pipe_inode_info *pipe) |
|
{ |
|
smp_mb(); |
|
if (waitqueue_active(&pipe->rd_wait)) |
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wake_up_interruptible(&pipe->rd_wait); |
|
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
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} |
|
|
|
/** |
|
* splice_to_pipe - fill passed data into a pipe |
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* @pipe: pipe to fill |
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* @spd: data to fill |
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* |
|
* Description: |
|
* @spd contains a map of pages and len/offset tuples, along with |
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* the struct pipe_buf_operations associated with these pages. This |
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* function will link that data to the pipe. |
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* |
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*/ |
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ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
|
struct splice_pipe_desc *spd) |
|
{ |
|
unsigned int spd_pages = spd->nr_pages; |
|
unsigned int tail = pipe->tail; |
|
unsigned int head = pipe->head; |
|
unsigned int mask = pipe->ring_size - 1; |
|
int ret = 0, page_nr = 0; |
|
|
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if (!spd_pages) |
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return 0; |
|
|
|
if (unlikely(!pipe->readers)) { |
|
send_sig(SIGPIPE, current, 0); |
|
ret = -EPIPE; |
|
goto out; |
|
} |
|
|
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while (!pipe_full(head, tail, pipe->max_usage)) { |
|
struct pipe_buffer *buf = &pipe->bufs[head & mask]; |
|
|
|
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; |
|
buf->flags = 0; |
|
|
|
head++; |
|
pipe->head = head; |
|
page_nr++; |
|
ret += buf->len; |
|
|
|
if (!--spd->nr_pages) |
|
break; |
|
} |
|
|
|
if (!ret) |
|
ret = -EAGAIN; |
|
|
|
out: |
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while (page_nr < spd_pages) |
|
spd->spd_release(spd, page_nr++); |
|
|
|
return ret; |
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} |
|
EXPORT_SYMBOL_GPL(splice_to_pipe); |
|
|
|
ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
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{ |
|
unsigned int head = pipe->head; |
|
unsigned int tail = pipe->tail; |
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unsigned int mask = pipe->ring_size - 1; |
|
int ret; |
|
|
|
if (unlikely(!pipe->readers)) { |
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send_sig(SIGPIPE, current, 0); |
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ret = -EPIPE; |
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} else if (pipe_full(head, tail, pipe->max_usage)) { |
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ret = -EAGAIN; |
|
} else { |
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pipe->bufs[head & mask] = *buf; |
|
pipe->head = head + 1; |
|
return buf->len; |
|
} |
|
pipe_buf_release(pipe, buf); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(add_to_pipe); |
|
|
|
/* |
|
* Check if we need to grow the arrays holding pages and partial page |
|
* descriptions. |
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*/ |
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int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) |
|
{ |
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unsigned int max_usage = READ_ONCE(pipe->max_usage); |
|
|
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spd->nr_pages_max = max_usage; |
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if (max_usage <= PIPE_DEF_BUFFERS) |
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return 0; |
|
|
|
spd->pages = kmalloc_array(max_usage, sizeof(struct page *), GFP_KERNEL); |
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spd->partial = kmalloc_array(max_usage, sizeof(struct partial_page), |
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GFP_KERNEL); |
|
|
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if (spd->pages && spd->partial) |
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return 0; |
|
|
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kfree(spd->pages); |
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kfree(spd->partial); |
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return -ENOMEM; |
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} |
|
|
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void splice_shrink_spd(struct splice_pipe_desc *spd) |
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{ |
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if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) |
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return; |
|
|
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kfree(spd->pages); |
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kfree(spd->partial); |
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} |
|
|
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/** |
|
* generic_file_splice_read - splice data from file to a pipe |
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* @in: file to splice from |
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* @ppos: position in @in |
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* @pipe: pipe to splice to |
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* @len: number of bytes to splice |
|
* @flags: splice modifier flags |
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* |
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* Description: |
|
* Will read pages from given file and fill them into a pipe. Can be |
|
* used as long as it has more or less sane ->read_iter(). |
|
* |
|
*/ |
|
ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
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struct pipe_inode_info *pipe, size_t len, |
|
unsigned int flags) |
|
{ |
|
struct iov_iter to; |
|
struct kiocb kiocb; |
|
unsigned int i_head; |
|
int ret; |
|
|
|
iov_iter_pipe(&to, READ, pipe, len); |
|
i_head = to.head; |
|
init_sync_kiocb(&kiocb, in); |
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kiocb.ki_pos = *ppos; |
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ret = call_read_iter(in, &kiocb, &to); |
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if (ret > 0) { |
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*ppos = kiocb.ki_pos; |
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file_accessed(in); |
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} else if (ret < 0) { |
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to.head = i_head; |
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to.iov_offset = 0; |
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iov_iter_advance(&to, 0); /* to free what was emitted */ |
|
/* |
|
* callers of ->splice_read() expect -EAGAIN on |
|
* "can't put anything in there", rather than -EFAULT. |
|
*/ |
|
if (ret == -EFAULT) |
|
ret = -EAGAIN; |
|
} |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL(generic_file_splice_read); |
|
|
|
const struct pipe_buf_operations default_pipe_buf_ops = { |
|
.release = generic_pipe_buf_release, |
|
.try_steal = generic_pipe_buf_try_steal, |
|
.get = generic_pipe_buf_get, |
|
}; |
|
|
|
/* Pipe buffer operations for a socket and similar. */ |
|
const struct pipe_buf_operations nosteal_pipe_buf_ops = { |
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.release = generic_pipe_buf_release, |
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.get = generic_pipe_buf_get, |
|
}; |
|
EXPORT_SYMBOL(nosteal_pipe_buf_ops); |
|
|
|
/* |
|
* 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, |
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struct pipe_buffer *buf, struct splice_desc *sd) |
|
{ |
|
struct file *file = sd->u.file; |
|
loff_t pos = sd->pos; |
|
int more; |
|
|
|
if (!likely(file->f_op->sendpage)) |
|
return -EINVAL; |
|
|
|
more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; |
|
|
|
if (sd->len < sd->total_len && |
|
pipe_occupancy(pipe->head, pipe->tail) > 1) |
|
more |= MSG_SENDPAGE_NOTLAST; |
|
|
|
return file->f_op->sendpage(file, buf->page, buf->offset, |
|
sd->len, &pos, more); |
|
} |
|
|
|
static void wakeup_pipe_writers(struct pipe_inode_info *pipe) |
|
{ |
|
smp_mb(); |
|
if (waitqueue_active(&pipe->wr_wait)) |
|
wake_up_interruptible(&pipe->wr_wait); |
|
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
|
} |
|
|
|
/** |
|
* splice_from_pipe_feed - feed available data from a pipe to a file |
|
* @pipe: pipe to splice from |
|
* @sd: information to @actor |
|
* @actor: handler that splices the data |
|
* |
|
* Description: |
|
* This function loops over the pipe and calls @actor to do the |
|
* actual moving of a single struct pipe_buffer to the desired |
|
* destination. It returns when there's no more buffers left in |
|
* the pipe or if the requested number of bytes (@sd->total_len) |
|
* have been copied. It returns a positive number (one) if the |
|
* pipe needs to be filled with more data, zero if the required |
|
* number of bytes have been copied and -errno on error. |
|
* |
|
* This, together with splice_from_pipe_{begin,end,next}, may be |
|
* used to implement the functionality of __splice_from_pipe() when |
|
* locking is required around copying the pipe buffers to the |
|
* destination. |
|
*/ |
|
static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, |
|
splice_actor *actor) |
|
{ |
|
unsigned int head = pipe->head; |
|
unsigned int tail = pipe->tail; |
|
unsigned int mask = pipe->ring_size - 1; |
|
int ret; |
|
|
|
while (!pipe_empty(head, tail)) { |
|
struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
|
|
|
sd->len = buf->len; |
|
if (sd->len > sd->total_len) |
|
sd->len = sd->total_len; |
|
|
|
ret = pipe_buf_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) { |
|
pipe_buf_release(pipe, buf); |
|
tail++; |
|
pipe->tail = tail; |
|
if (pipe->files) |
|
sd->need_wakeup = true; |
|
} |
|
|
|
if (!sd->total_len) |
|
return 0; |
|
} |
|
|
|
return 1; |
|
} |
|
|
|
/* We know we have a pipe buffer, but maybe it's empty? */ |
|
static inline bool eat_empty_buffer(struct pipe_inode_info *pipe) |
|
{ |
|
unsigned int tail = pipe->tail; |
|
unsigned int mask = pipe->ring_size - 1; |
|
struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
|
|
|
if (unlikely(!buf->len)) { |
|
pipe_buf_release(pipe, buf); |
|
pipe->tail = tail+1; |
|
return true; |
|
} |
|
|
|
return false; |
|
} |
|
|
|
/** |
|
* splice_from_pipe_next - wait for some data to splice from |
|
* @pipe: pipe to splice from |
|
* @sd: information about the splice operation |
|
* |
|
* Description: |
|
* This function will wait for some data and return a positive |
|
* value (one) if pipe buffers are available. It will return zero |
|
* or -errno if no more data needs to be spliced. |
|
*/ |
|
static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) |
|
{ |
|
/* |
|
* Check for signal early to make process killable when there are |
|
* always buffers available |
|
*/ |
|
if (signal_pending(current)) |
|
return -ERESTARTSYS; |
|
|
|
repeat: |
|
while (pipe_empty(pipe->head, pipe->tail)) { |
|
if (!pipe->writers) |
|
return 0; |
|
|
|
if (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_readable(pipe); |
|
} |
|
|
|
if (eat_empty_buffer(pipe)) |
|
goto repeat; |
|
|
|
return 1; |
|
} |
|
|
|
/** |
|
* splice_from_pipe_begin - start splicing from pipe |
|
* @sd: information about the splice operation |
|
* |
|
* Description: |
|
* This function should be called before a loop containing |
|
* splice_from_pipe_next() and splice_from_pipe_feed() to |
|
* initialize the necessary fields of @sd. |
|
*/ |
|
static void splice_from_pipe_begin(struct splice_desc *sd) |
|
{ |
|
sd->num_spliced = 0; |
|
sd->need_wakeup = false; |
|
} |
|
|
|
/** |
|
* splice_from_pipe_end - finish splicing from pipe |
|
* @pipe: pipe to splice from |
|
* @sd: information about the splice operation |
|
* |
|
* Description: |
|
* This function will wake up pipe writers if necessary. It should |
|
* be called after a loop containing splice_from_pipe_next() and |
|
* splice_from_pipe_feed(). |
|
*/ |
|
static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) |
|
{ |
|
if (sd->need_wakeup) |
|
wakeup_pipe_writers(pipe); |
|
} |
|
|
|
/** |
|
* __splice_from_pipe - splice data from a pipe to given actor |
|
* @pipe: pipe to splice from |
|
* @sd: information to @actor |
|
* @actor: handler that splices the data |
|
* |
|
* Description: |
|
* This function does little more than loop over the pipe and call |
|
* @actor to do the actual moving of a single struct pipe_buffer to |
|
* the desired destination. See pipe_to_file, pipe_to_sendpage, or |
|
* pipe_to_user. |
|
* |
|
*/ |
|
ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, |
|
splice_actor *actor) |
|
{ |
|
int ret; |
|
|
|
splice_from_pipe_begin(sd); |
|
do { |
|
cond_resched(); |
|
ret = splice_from_pipe_next(pipe, sd); |
|
if (ret > 0) |
|
ret = splice_from_pipe_feed(pipe, sd, actor); |
|
} while (ret > 0); |
|
splice_from_pipe_end(pipe, sd); |
|
|
|
return sd->num_spliced ? sd->num_spliced : ret; |
|
} |
|
EXPORT_SYMBOL(__splice_from_pipe); |
|
|
|
/** |
|
* splice_from_pipe - splice data from a pipe to a file |
|
* @pipe: pipe to splice from |
|
* @out: file to splice to |
|
* @ppos: position in @out |
|
* @len: how many bytes to splice |
|
* @flags: splice modifier flags |
|
* @actor: handler that splices the data |
|
* |
|
* Description: |
|
* See __splice_from_pipe. This function locks the pipe inode, |
|
* otherwise it's identical to __splice_from_pipe(). |
|
* |
|
*/ |
|
ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, |
|
loff_t *ppos, size_t len, unsigned int flags, |
|
splice_actor *actor) |
|
{ |
|
ssize_t ret; |
|
struct splice_desc sd = { |
|
.total_len = len, |
|
.flags = flags, |
|
.pos = *ppos, |
|
.u.file = out, |
|
}; |
|
|
|
pipe_lock(pipe); |
|
ret = __splice_from_pipe(pipe, &sd, actor); |
|
pipe_unlock(pipe); |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* iter_file_splice_write - splice data from a pipe to a file |
|
* @pipe: pipe info |
|
* @out: file to write to |
|
* @ppos: position in @out |
|
* @len: number of bytes to splice |
|
* @flags: splice modifier flags |
|
* |
|
* Description: |
|
* Will either move or copy pages (determined by @flags options) from |
|
* the given pipe inode to the given file. |
|
* This one is ->write_iter-based. |
|
* |
|
*/ |
|
ssize_t |
|
iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, |
|
loff_t *ppos, size_t len, unsigned int flags) |
|
{ |
|
struct splice_desc sd = { |
|
.total_len = len, |
|
.flags = flags, |
|
.pos = *ppos, |
|
.u.file = out, |
|
}; |
|
int nbufs = pipe->max_usage; |
|
struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), |
|
GFP_KERNEL); |
|
ssize_t ret; |
|
|
|
if (unlikely(!array)) |
|
return -ENOMEM; |
|
|
|
pipe_lock(pipe); |
|
|
|
splice_from_pipe_begin(&sd); |
|
while (sd.total_len) { |
|
struct iov_iter from; |
|
unsigned int head, tail, mask; |
|
size_t left; |
|
int n; |
|
|
|
ret = splice_from_pipe_next(pipe, &sd); |
|
if (ret <= 0) |
|
break; |
|
|
|
if (unlikely(nbufs < pipe->max_usage)) { |
|
kfree(array); |
|
nbufs = pipe->max_usage; |
|
array = kcalloc(nbufs, sizeof(struct bio_vec), |
|
GFP_KERNEL); |
|
if (!array) { |
|
ret = -ENOMEM; |
|
break; |
|
} |
|
} |
|
|
|
head = pipe->head; |
|
tail = pipe->tail; |
|
mask = pipe->ring_size - 1; |
|
|
|
/* build the vector */ |
|
left = sd.total_len; |
|
for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) { |
|
struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
|
size_t this_len = buf->len; |
|
|
|
/* zero-length bvecs are not supported, skip them */ |
|
if (!this_len) |
|
continue; |
|
this_len = min(this_len, left); |
|
|
|
ret = pipe_buf_confirm(pipe, buf); |
|
if (unlikely(ret)) { |
|
if (ret == -ENODATA) |
|
ret = 0; |
|
goto done; |
|
} |
|
|
|
array[n].bv_page = buf->page; |
|
array[n].bv_len = this_len; |
|
array[n].bv_offset = buf->offset; |
|
left -= this_len; |
|
n++; |
|
} |
|
|
|
iov_iter_bvec(&from, WRITE, array, n, sd.total_len - left); |
|
ret = vfs_iter_write(out, &from, &sd.pos, 0); |
|
if (ret <= 0) |
|
break; |
|
|
|
sd.num_spliced += ret; |
|
sd.total_len -= ret; |
|
*ppos = sd.pos; |
|
|
|
/* dismiss the fully eaten buffers, adjust the partial one */ |
|
tail = pipe->tail; |
|
while (ret) { |
|
struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
|
if (ret >= buf->len) { |
|
ret -= buf->len; |
|
buf->len = 0; |
|
pipe_buf_release(pipe, buf); |
|
tail++; |
|
pipe->tail = tail; |
|
if (pipe->files) |
|
sd.need_wakeup = true; |
|
} else { |
|
buf->offset += ret; |
|
buf->len -= ret; |
|
ret = 0; |
|
} |
|
} |
|
} |
|
done: |
|
kfree(array); |
|
splice_from_pipe_end(pipe, &sd); |
|
|
|
pipe_unlock(pipe); |
|
|
|
if (sd.num_spliced) |
|
ret = sd.num_spliced; |
|
|
|
return ret; |
|
} |
|
|
|
EXPORT_SYMBOL(iter_file_splice_write); |
|
|
|
/** |
|
* 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); |
|
|
|
static int warn_unsupported(struct file *file, const char *op) |
|
{ |
|
pr_debug_ratelimited( |
|
"splice %s not supported for file %pD4 (pid: %d comm: %.20s)\n", |
|
op, file, current->pid, current->comm); |
|
return -EINVAL; |
|
} |
|
|
|
/* |
|
* 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) |
|
{ |
|
if (unlikely(!out->f_op->splice_write)) |
|
return warn_unsupported(out, "write"); |
|
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) |
|
{ |
|
unsigned int p_space; |
|
int ret; |
|
|
|
if (unlikely(!(in->f_mode & FMODE_READ))) |
|
return -EBADF; |
|
|
|
/* Don't try to read more the pipe has space for. */ |
|
p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail); |
|
len = min_t(size_t, len, p_space << PAGE_SHIFT); |
|
|
|
ret = rw_verify_area(READ, in, ppos, len); |
|
if (unlikely(ret < 0)) |
|
return ret; |
|
|
|
if (unlikely(len > MAX_RW_COUNT)) |
|
len = MAX_RW_COUNT; |
|
|
|
if (unlikely(!in->f_op->splice_read)) |
|
return warn_unsupported(in, "read"); |
|
return in->f_op->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, more; |
|
|
|
/* |
|
* We require the input being a regular file, as we don't want to |
|
* randomly drop data for eg socket -> socket splicing. Use the |
|
* piped splicing for that! |
|
*/ |
|
i_mode = file_inode(in)->i_mode; |
|
if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
|
return -EINVAL; |
|
|
|
/* |
|
* neither in nor out is a pipe, setup an internal pipe attached to |
|
* 'out' and transfer the wanted data from 'in' to 'out' through that |
|
*/ |
|
pipe = current->splice_pipe; |
|
if (unlikely(!pipe)) { |
|
pipe = alloc_pipe_info(); |
|
if (!pipe) |
|
return -ENOMEM; |
|
|
|
/* |
|
* We don't have an immediate reader, but we'll read the stuff |
|
* out of the pipe right after the splice_to_pipe(). So set |
|
* PIPE_READERS appropriately. |
|
*/ |
|
pipe->readers = 1; |
|
|
|
current->splice_pipe = pipe; |
|
} |
|
|
|
/* |
|
* Do the splice. |
|
*/ |
|
ret = 0; |
|
bytes = 0; |
|
len = sd->total_len; |
|
flags = sd->flags; |
|
|
|
/* |
|
* Don't block on output, we have to drain the direct pipe. |
|
*/ |
|
sd->flags &= ~SPLICE_F_NONBLOCK; |
|
more = sd->flags & SPLICE_F_MORE; |
|
|
|
WARN_ON_ONCE(!pipe_empty(pipe->head, pipe->tail)); |
|
|
|
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; |
|
|
|
/* |
|
* If more data is pending, set SPLICE_F_MORE |
|
* If this is the last data and SPLICE_F_MORE was not set |
|
* initially, clears it. |
|
*/ |
|
if (read_len < len) |
|
sd->flags |= SPLICE_F_MORE; |
|
else if (!more) |
|
sd->flags &= ~SPLICE_F_MORE; |
|
/* |
|
* 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->tail = pipe->head = 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->ring_size; i++) { |
|
struct pipe_buffer *buf = &pipe->bufs[i]; |
|
|
|
if (buf->ops) |
|
pipe_buf_release(pipe, buf); |
|
} |
|
|
|
if (!bytes) |
|
bytes = ret; |
|
|
|
goto done; |
|
} |
|
EXPORT_SYMBOL(splice_direct_to_actor); |
|
|
|
static int direct_splice_actor(struct pipe_inode_info *pipe, |
|
struct splice_desc *sd) |
|
{ |
|
struct file *file = sd->u.file; |
|
|
|
return do_splice_from(pipe, file, sd->opos, sd->total_len, |
|
sd->flags); |
|
} |
|
|
|
/** |
|
* do_splice_direct - splices data directly between two files |
|
* @in: file to splice from |
|
* @ppos: input file offset |
|
* @out: file to splice to |
|
* @opos: output file offset |
|
* @len: number of bytes to splice |
|
* @flags: splice modifier flags |
|
* |
|
* Description: |
|
* For use by do_sendfile(). splice can easily emulate sendfile, but |
|
* doing it in the application would incur an extra system call |
|
* (splice in + splice out, as compared to just sendfile()). So this helper |
|
* can splice directly through a process-private pipe. |
|
* |
|
*/ |
|
long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
|
loff_t *opos, size_t len, unsigned int flags) |
|
{ |
|
struct splice_desc sd = { |
|
.len = len, |
|
.total_len = len, |
|
.flags = flags, |
|
.pos = *ppos, |
|
.u.file = out, |
|
.opos = opos, |
|
}; |
|
long ret; |
|
|
|
if (unlikely(!(out->f_mode & FMODE_WRITE))) |
|
return -EBADF; |
|
|
|
if (unlikely(out->f_flags & O_APPEND)) |
|
return -EINVAL; |
|
|
|
ret = rw_verify_area(WRITE, out, opos, len); |
|
if (unlikely(ret < 0)) |
|
return ret; |
|
|
|
ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
|
if (ret > 0) |
|
*ppos = sd.pos; |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL(do_splice_direct); |
|
|
|
static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) |
|
{ |
|
for (;;) { |
|
if (unlikely(!pipe->readers)) { |
|
send_sig(SIGPIPE, current, 0); |
|
return -EPIPE; |
|
} |
|
if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
|
return 0; |
|
if (flags & SPLICE_F_NONBLOCK) |
|
return -EAGAIN; |
|
if (signal_pending(current)) |
|
return -ERESTARTSYS; |
|
pipe_wait_writable(pipe); |
|
} |
|
} |
|
|
|
static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, |
|
struct pipe_inode_info *opipe, |
|
size_t len, unsigned int flags); |
|
|
|
long splice_file_to_pipe(struct file *in, |
|
struct pipe_inode_info *opipe, |
|
loff_t *offset, |
|
size_t len, unsigned int flags) |
|
{ |
|
long ret; |
|
|
|
pipe_lock(opipe); |
|
ret = wait_for_space(opipe, flags); |
|
if (!ret) |
|
ret = do_splice_to(in, offset, opipe, len, flags); |
|
pipe_unlock(opipe); |
|
if (ret > 0) |
|
wakeup_pipe_readers(opipe); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Determine where to splice to/from. |
|
*/ |
|
long do_splice(struct file *in, loff_t *off_in, struct file *out, |
|
loff_t *off_out, size_t len, unsigned int flags) |
|
{ |
|
struct pipe_inode_info *ipipe; |
|
struct pipe_inode_info *opipe; |
|
loff_t offset; |
|
long ret; |
|
|
|
if (unlikely(!(in->f_mode & FMODE_READ) || |
|
!(out->f_mode & FMODE_WRITE))) |
|
return -EBADF; |
|
|
|
ipipe = get_pipe_info(in, true); |
|
opipe = get_pipe_info(out, true); |
|
|
|
if (ipipe && opipe) { |
|
if (off_in || off_out) |
|
return -ESPIPE; |
|
|
|
/* Splicing to self would be fun, but... */ |
|
if (ipipe == opipe) |
|
return -EINVAL; |
|
|
|
if ((in->f_flags | out->f_flags) & O_NONBLOCK) |
|
flags |= SPLICE_F_NONBLOCK; |
|
|
|
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; |
|
offset = *off_out; |
|
} else { |
|
offset = out->f_pos; |
|
} |
|
|
|
if (unlikely(out->f_flags & O_APPEND)) |
|
return -EINVAL; |
|
|
|
ret = rw_verify_area(WRITE, out, &offset, len); |
|
if (unlikely(ret < 0)) |
|
return ret; |
|
|
|
if (in->f_flags & O_NONBLOCK) |
|
flags |= SPLICE_F_NONBLOCK; |
|
|
|
file_start_write(out); |
|
ret = do_splice_from(ipipe, out, &offset, len, flags); |
|
file_end_write(out); |
|
|
|
if (!off_out) |
|
out->f_pos = offset; |
|
else |
|
*off_out = offset; |
|
|
|
return ret; |
|
} |
|
|
|
if (opipe) { |
|
if (off_out) |
|
return -ESPIPE; |
|
if (off_in) { |
|
if (!(in->f_mode & FMODE_PREAD)) |
|
return -EINVAL; |
|
offset = *off_in; |
|
} else { |
|
offset = in->f_pos; |
|
} |
|
|
|
if (out->f_flags & O_NONBLOCK) |
|
flags |= SPLICE_F_NONBLOCK; |
|
|
|
ret = splice_file_to_pipe(in, opipe, &offset, len, flags); |
|
if (!off_in) |
|
in->f_pos = offset; |
|
else |
|
*off_in = offset; |
|
|
|
return ret; |
|
} |
|
|
|
return -EINVAL; |
|
} |
|
|
|
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_in = NULL, *__off_out = NULL; |
|
long ret; |
|
|
|
ipipe = get_pipe_info(in, true); |
|
opipe = get_pipe_info(out, true); |
|
|
|
if (ipipe && off_in) |
|
return -ESPIPE; |
|
if (opipe && off_out) |
|
return -ESPIPE; |
|
|
|
if (off_out) { |
|
if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
|
return -EFAULT; |
|
__off_out = &offset; |
|
} |
|
if (off_in) { |
|
if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
|
return -EFAULT; |
|
__off_in = &offset; |
|
} |
|
|
|
ret = do_splice(in, __off_in, out, __off_out, len, flags); |
|
if (ret < 0) |
|
return ret; |
|
|
|
if (__off_out && copy_to_user(off_out, __off_out, sizeof(loff_t))) |
|
return -EFAULT; |
|
if (__off_in && copy_to_user(off_in, __off_in, sizeof(loff_t))) |
|
return -EFAULT; |
|
|
|
return ret; |
|
} |
|
|
|
static int iter_to_pipe(struct iov_iter *from, |
|
struct pipe_inode_info *pipe, |
|
unsigned flags) |
|
{ |
|
struct pipe_buffer buf = { |
|
.ops = &user_page_pipe_buf_ops, |
|
.flags = flags |
|
}; |
|
size_t total = 0; |
|
int ret = 0; |
|
bool failed = false; |
|
|
|
while (iov_iter_count(from) && !failed) { |
|
struct page *pages[16]; |
|
ssize_t copied; |
|
size_t start; |
|
int n; |
|
|
|
copied = iov_iter_get_pages(from, pages, ~0UL, 16, &start); |
|
if (copied <= 0) { |
|
ret = copied; |
|
break; |
|
} |
|
|
|
for (n = 0; copied; n++, start = 0) { |
|
int size = min_t(int, copied, PAGE_SIZE - start); |
|
if (!failed) { |
|
buf.page = pages[n]; |
|
buf.offset = start; |
|
buf.len = size; |
|
ret = add_to_pipe(pipe, &buf); |
|
if (unlikely(ret < 0)) { |
|
failed = true; |
|
} else { |
|
iov_iter_advance(from, ret); |
|
total += ret; |
|
} |
|
} else { |
|
put_page(pages[n]); |
|
} |
|
copied -= size; |
|
} |
|
} |
|
return total ? total : ret; |
|
} |
|
|
|
static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
|
struct splice_desc *sd) |
|
{ |
|
int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); |
|
return n == sd->len ? n : -EFAULT; |
|
} |
|
|
|
/* |
|
* For lack of a better implementation, implement vmsplice() to userspace |
|
* as a simple copy of the pipes pages to the user iov. |
|
*/ |
|
static long vmsplice_to_user(struct file *file, struct iov_iter *iter, |
|
unsigned int flags) |
|
{ |
|
struct pipe_inode_info *pipe = get_pipe_info(file, true); |
|
struct splice_desc sd = { |
|
.total_len = iov_iter_count(iter), |
|
.flags = flags, |
|
.u.data = iter |
|
}; |
|
long ret = 0; |
|
|
|
if (!pipe) |
|
return -EBADF; |
|
|
|
if (sd.total_len) { |
|
pipe_lock(pipe); |
|
ret = __splice_from_pipe(pipe, &sd, pipe_to_user); |
|
pipe_unlock(pipe); |
|
} |
|
|
|
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, struct iov_iter *iter, |
|
unsigned int flags) |
|
{ |
|
struct pipe_inode_info *pipe; |
|
long ret = 0; |
|
unsigned buf_flag = 0; |
|
|
|
if (flags & SPLICE_F_GIFT) |
|
buf_flag = PIPE_BUF_FLAG_GIFT; |
|
|
|
pipe = get_pipe_info(file, true); |
|
if (!pipe) |
|
return -EBADF; |
|
|
|
pipe_lock(pipe); |
|
ret = wait_for_space(pipe, flags); |
|
if (!ret) |
|
ret = iter_to_pipe(iter, pipe, buf_flag); |
|
pipe_unlock(pipe); |
|
if (ret > 0) |
|
wakeup_pipe_readers(pipe); |
|
return ret; |
|
} |
|
|
|
static int vmsplice_type(struct fd f, int *type) |
|
{ |
|
if (!f.file) |
|
return -EBADF; |
|
if (f.file->f_mode & FMODE_WRITE) { |
|
*type = WRITE; |
|
} else if (f.file->f_mode & FMODE_READ) { |
|
*type = READ; |
|
} else { |
|
fdput(f); |
|
return -EBADF; |
|
} |
|
return 0; |
|
} |
|
|
|
/* |
|
* 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 *, uiov, |
|
unsigned long, nr_segs, unsigned int, flags) |
|
{ |
|
struct iovec iovstack[UIO_FASTIOV]; |
|
struct iovec *iov = iovstack; |
|
struct iov_iter iter; |
|
ssize_t error; |
|
struct fd f; |
|
int type; |
|
|
|
if (unlikely(flags & ~SPLICE_F_ALL)) |
|
return -EINVAL; |
|
|
|
f = fdget(fd); |
|
error = vmsplice_type(f, &type); |
|
if (error) |
|
return error; |
|
|
|
error = import_iovec(type, uiov, nr_segs, |
|
ARRAY_SIZE(iovstack), &iov, &iter); |
|
if (error < 0) |
|
goto out_fdput; |
|
|
|
if (!iov_iter_count(&iter)) |
|
error = 0; |
|
else if (iov_iter_rw(&iter) == WRITE) |
|
error = vmsplice_to_pipe(f.file, &iter, flags); |
|
else |
|
error = vmsplice_to_user(f.file, &iter, flags); |
|
|
|
kfree(iov); |
|
out_fdput: |
|
fdput(f); |
|
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) |
|
{ |
|
struct fd in, out; |
|
long error; |
|
|
|
if (unlikely(!len)) |
|
return 0; |
|
|
|
if (unlikely(flags & ~SPLICE_F_ALL)) |
|
return -EINVAL; |
|
|
|
error = -EBADF; |
|
in = fdget(fd_in); |
|
if (in.file) { |
|
out = fdget(fd_out); |
|
if (out.file) { |
|
error = __do_splice(in.file, off_in, out.file, off_out, |
|
len, flags); |
|
fdput(out); |
|
} |
|
fdput(in); |
|
} |
|
return error; |
|
} |
|
|
|
/* |
|
* Make sure there's data to read. Wait for input if we can, otherwise |
|
* return an appropriate error. |
|
*/ |
|
static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
|
{ |
|
int ret; |
|
|
|
/* |
|
* Check the pipe occupancy without the inode lock first. This function |
|
* is speculative anyways, so missing one is ok. |
|
*/ |
|
if (!pipe_empty(pipe->head, pipe->tail)) |
|
return 0; |
|
|
|
ret = 0; |
|
pipe_lock(pipe); |
|
|
|
while (pipe_empty(pipe->head, pipe->tail)) { |
|
if (signal_pending(current)) { |
|
ret = -ERESTARTSYS; |
|
break; |
|
} |
|
if (!pipe->writers) |
|
break; |
|
if (flags & SPLICE_F_NONBLOCK) { |
|
ret = -EAGAIN; |
|
break; |
|
} |
|
pipe_wait_readable(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 pipe occupancy without the inode lock first. This function |
|
* is speculative anyways, so missing one is ok. |
|
*/ |
|
if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
|
return 0; |
|
|
|
ret = 0; |
|
pipe_lock(pipe); |
|
|
|
while (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) { |
|
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_wait_writable(pipe); |
|
} |
|
|
|
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; |
|
unsigned int i_head, o_head; |
|
unsigned int i_tail, o_tail; |
|
unsigned int i_mask, o_mask; |
|
int ret = 0; |
|
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); |
|
|
|
i_tail = ipipe->tail; |
|
i_mask = ipipe->ring_size - 1; |
|
o_head = opipe->head; |
|
o_mask = opipe->ring_size - 1; |
|
|
|
do { |
|
size_t o_len; |
|
|
|
if (!opipe->readers) { |
|
send_sig(SIGPIPE, current, 0); |
|
if (!ret) |
|
ret = -EPIPE; |
|
break; |
|
} |
|
|
|
i_head = ipipe->head; |
|
o_tail = opipe->tail; |
|
|
|
if (pipe_empty(i_head, i_tail) && !ipipe->writers) |
|
break; |
|
|
|
/* |
|
* Cannot make any progress, because either the input |
|
* pipe is empty or the output pipe is full. |
|
*/ |
|
if (pipe_empty(i_head, i_tail) || |
|
pipe_full(o_head, o_tail, opipe->max_usage)) { |
|
/* 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[i_tail & i_mask]; |
|
obuf = &opipe->bufs[o_head & o_mask]; |
|
|
|
if (len >= ibuf->len) { |
|
/* |
|
* Simply move the whole buffer from ipipe to opipe |
|
*/ |
|
*obuf = *ibuf; |
|
ibuf->ops = NULL; |
|
i_tail++; |
|
ipipe->tail = i_tail; |
|
input_wakeup = true; |
|
o_len = obuf->len; |
|
o_head++; |
|
opipe->head = o_head; |
|
} else { |
|
/* |
|
* Get a reference to this pipe buffer, |
|
* so we can copy the contents over. |
|
*/ |
|
if (!pipe_buf_get(ipipe, ibuf)) { |
|
if (ret == 0) |
|
ret = -EFAULT; |
|
break; |
|
} |
|
*obuf = *ibuf; |
|
|
|
/* |
|
* Don't inherit the gift and merge flags, we need to |
|
* prevent multiple steals of this page. |
|
*/ |
|
obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
|
obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; |
|
|
|
obuf->len = len; |
|
ibuf->offset += len; |
|
ibuf->len -= len; |
|
o_len = len; |
|
o_head++; |
|
opipe->head = o_head; |
|
} |
|
ret += o_len; |
|
len -= o_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; |
|
unsigned int i_head, o_head; |
|
unsigned int i_tail, o_tail; |
|
unsigned int i_mask, o_mask; |
|
int ret = 0; |
|
|
|
/* |
|
* 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); |
|
|
|
i_tail = ipipe->tail; |
|
i_mask = ipipe->ring_size - 1; |
|
o_head = opipe->head; |
|
o_mask = opipe->ring_size - 1; |
|
|
|
do { |
|
if (!opipe->readers) { |
|
send_sig(SIGPIPE, current, 0); |
|
if (!ret) |
|
ret = -EPIPE; |
|
break; |
|
} |
|
|
|
i_head = ipipe->head; |
|
o_tail = opipe->tail; |
|
|
|
/* |
|
* If we have iterated all input buffers or run out of |
|
* output room, break. |
|
*/ |
|
if (pipe_empty(i_head, i_tail) || |
|
pipe_full(o_head, o_tail, opipe->max_usage)) |
|
break; |
|
|
|
ibuf = &ipipe->bufs[i_tail & i_mask]; |
|
obuf = &opipe->bufs[o_head & o_mask]; |
|
|
|
/* |
|
* Get a reference to this pipe buffer, |
|
* so we can copy the contents over. |
|
*/ |
|
if (!pipe_buf_get(ipipe, ibuf)) { |
|
if (ret == 0) |
|
ret = -EFAULT; |
|
break; |
|
} |
|
|
|
*obuf = *ibuf; |
|
|
|
/* |
|
* Don't inherit the gift and merge flag, we need to prevent |
|
* multiple steals of this page. |
|
*/ |
|
obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
|
obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; |
|
|
|
if (obuf->len > len) |
|
obuf->len = len; |
|
ret += obuf->len; |
|
len -= obuf->len; |
|
|
|
o_head++; |
|
opipe->head = o_head; |
|
i_tail++; |
|
} 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); |
|
|
|
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. |
|
*/ |
|
long do_tee(struct file *in, struct file *out, size_t len, unsigned int flags) |
|
{ |
|
struct pipe_inode_info *ipipe = get_pipe_info(in, true); |
|
struct pipe_inode_info *opipe = get_pipe_info(out, true); |
|
int ret = -EINVAL; |
|
|
|
if (unlikely(!(in->f_mode & FMODE_READ) || |
|
!(out->f_mode & FMODE_WRITE))) |
|
return -EBADF; |
|
|
|
/* |
|
* Duplicate the contents of ipipe to opipe without actually |
|
* copying the data. |
|
*/ |
|
if (ipipe && opipe && ipipe != opipe) { |
|
if ((in->f_flags | out->f_flags) & O_NONBLOCK) |
|
flags |= SPLICE_F_NONBLOCK; |
|
|
|
/* |
|
* Keep going, unless we encounter an error. The ipipe/opipe |
|
* ordering doesn't really matter. |
|
*/ |
|
ret = ipipe_prep(ipipe, flags); |
|
if (!ret) { |
|
ret = opipe_prep(opipe, flags); |
|
if (!ret) |
|
ret = link_pipe(ipipe, opipe, len, flags); |
|
} |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) |
|
{ |
|
struct fd in, out; |
|
int error; |
|
|
|
if (unlikely(flags & ~SPLICE_F_ALL)) |
|
return -EINVAL; |
|
|
|
if (unlikely(!len)) |
|
return 0; |
|
|
|
error = -EBADF; |
|
in = fdget(fdin); |
|
if (in.file) { |
|
out = fdget(fdout); |
|
if (out.file) { |
|
error = do_tee(in.file, out.file, len, flags); |
|
fdput(out); |
|
} |
|
fdput(in); |
|
} |
|
|
|
return error; |
|
}
|
|
|