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-----BEGIN PGP SIGNATURE----- iQJEBAABCAAuFiEEwPw5LcreJtl1+l5K99NY+ylx4KYFAmAtmIwQHGF4Ym9lQGtl cm5lbC5kawAKCRD301j7KXHgplzLEAC5O+3rBM8QuiJdo39Yppmuw4hDJ6hOKynP EJQLKQQi0VfXgU+MprGvcbpFYmNbgICvUICQkEzJuk++kPCu/BJtJz0yErQeLgS+ RdXiPV6enbF7iRML5TVRTr1q/z7sJMXcIIJ8Pz/rU/JNfGYExVd0WfnEY9mp1jOt Bl9V+qyTazdP+Ma4+uEPatSayqcdi1rxB5I+7v/sLiOvKZZWkaRZjUZ/mxAjUfvK dBOOPjMygEo3tCLkIyyA6lpLvr1r+SUZhLuebRLEKa3To3TW6RtoG0qwpKmI2iKw ylLeVLB60nM9RUxjflVOfBsHxz1bDg5Ve86y5nCjQd4Jo8x1c4DnecyGE5/Tu8Rg rgbsfD6nFWzhDCvcZT0XrfQ4ZAjIL2IfT+ypQiQ6UlRd3hvIKRmzWMkjuH2svr0u ey9Kq+lYerI4cM0F3W73gzUKdIQOuCzBCYxQuSQQomscBa7FCInyU192dAI9Aj6l Yd06mgKu6qCx6zLv6JfpBqaBHZMwyGE4dmZgPQFuuwO+b4N+Ck3Jm5fzEzw/xIxQ wdo/DlsAl60BXentB6FByGBJaCjVdSymRqN/xNCAbFKCjmr6TLBuXPfg1gYYO7xC VOcVjWe8iN3wWHZab3t2mxMKH9B9B/KKzIhu6TNHSmgtQ5paZPRCBx995pDyRw26 WC22RGC2MA== =os1E -----END PGP SIGNATURE----- Merge tag 'for-5.12/block-2021-02-17' of git://git.kernel.dk/linux-block Pull core block updates from Jens Axboe: "Another nice round of removing more code than what is added, mostly due to Christoph's relentless pursuit of tech debt removal/cleanups. This pull request contains: - Two series of BFQ improvements (Paolo, Jan, Jia) - Block iov_iter improvements (Pavel) - bsg error path fix (Pan) - blk-mq scheduler improvements (Jan) - -EBUSY discard fix (Jan) - bvec allocation improvements (Ming, Christoph) - bio allocation and init improvements (Christoph) - Store bdev pointer in bio instead of gendisk + partno (Christoph) - Block trace point cleanups (Christoph) - hard read-only vs read-only split (Christoph) - Block based swap cleanups (Christoph) - Zoned write granularity support (Damien) - Various fixes/tweaks (Chunguang, Guoqing, Lei, Lukas, Huhai)" * tag 'for-5.12/block-2021-02-17' of git://git.kernel.dk/linux-block: (104 commits) mm: simplify swapdev_block sd_zbc: clear zone resources for non-zoned case block: introduce blk_queue_clear_zone_settings() zonefs: use zone write granularity as block size block: introduce zone_write_granularity limit block: use blk_queue_set_zoned in add_partition() nullb: use blk_queue_set_zoned() to setup zoned devices nvme: cleanup zone information initialization block: document zone_append_max_bytes attribute block: use bi_max_vecs to find the bvec pool md/raid10: remove dead code in reshape_request block: mark the bio as cloned in bio_iov_bvec_set block: set BIO_NO_PAGE_REF in bio_iov_bvec_set block: remove a layer of indentation in bio_iov_iter_get_pages block: turn the nr_iovecs argument to bio_alloc* into an unsigned short block: remove the 1 and 4 vec bvec_slabs entries block: streamline bvec_alloc block: factor out a bvec_alloc_gfp helper block: move struct biovec_slab to bio.c block: reuse BIO_INLINE_VECS for integrity bvecs ...
1722 lines
39 KiB
C
1722 lines
39 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
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* "splice": joining two ropes together by interweaving their strands.
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*
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* This is the "extended pipe" functionality, where a pipe is used as
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* an arbitrary in-memory buffer. Think of a pipe as a small kernel
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* buffer that you can use to transfer data from one end to the other.
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*
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* The traditional unix read/write is extended with a "splice()" operation
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* that transfers data buffers to or from a pipe buffer.
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*
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* Named by Larry McVoy, original implementation from Linus, extended by
|
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* Jens to support splicing to files, network, direct splicing, etc and
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* fixing lots of bugs.
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*
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* Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk>
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* Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org>
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* Copyright (C) 2006 Ingo Molnar <mingo@elte.hu>
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*
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*/
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#include <linux/bvec.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/pagemap.h>
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#include <linux/splice.h>
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#include <linux/memcontrol.h>
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#include <linux/mm_inline.h>
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#include <linux/swap.h>
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#include <linux/writeback.h>
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#include <linux/export.h>
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#include <linux/syscalls.h>
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#include <linux/uio.h>
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#include <linux/security.h>
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#include <linux/gfp.h>
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#include <linux/socket.h>
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#include <linux/sched/signal.h>
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#include "internal.h"
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/*
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* Attempt to steal a page from a pipe buffer. This should perhaps go into
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* a vm helper function, it's already simplified quite a bit by the
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* addition of remove_mapping(). If success is returned, the caller may
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* attempt to reuse this page for another destination.
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*/
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static bool page_cache_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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struct page *page = buf->page;
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struct address_space *mapping;
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lock_page(page);
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mapping = page_mapping(page);
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if (mapping) {
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WARN_ON(!PageUptodate(page));
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/*
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* At least for ext2 with nobh option, we need to wait on
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* writeback completing on this page, since we'll remove it
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* from the pagecache. Otherwise truncate wont wait on the
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* page, allowing the disk blocks to be reused by someone else
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* before we actually wrote our data to them. fs corruption
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* ensues.
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*/
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wait_on_page_writeback(page);
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if (page_has_private(page) &&
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!try_to_release_page(page, GFP_KERNEL))
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goto out_unlock;
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|
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/*
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* If we succeeded in removing the mapping, set LRU flag
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* and return good.
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*/
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if (remove_mapping(mapping, page)) {
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buf->flags |= PIPE_BUF_FLAG_LRU;
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return true;
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}
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}
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/*
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* Raced with truncate or failed to remove page from current
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* address space, unlock and return failure.
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*/
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out_unlock:
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unlock_page(page);
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return false;
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}
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static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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put_page(buf->page);
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buf->flags &= ~PIPE_BUF_FLAG_LRU;
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}
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|
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/*
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* Check whether the contents of buf is OK to access. Since the content
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* is a page cache page, IO may be in flight.
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*/
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static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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struct page *page = buf->page;
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int err;
|
|
|
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if (!PageUptodate(page)) {
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lock_page(page);
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|
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/*
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* Page got truncated/unhashed. This will cause a 0-byte
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* splice, if this is the first page.
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*/
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if (!page->mapping) {
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err = -ENODATA;
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goto error;
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}
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|
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/*
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|
* Uh oh, read-error from disk.
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*/
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if (!PageUptodate(page)) {
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err = -EIO;
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goto error;
|
|
}
|
|
|
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/*
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* Page is ok afterall, we are done.
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*/
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unlock_page(page);
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}
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return 0;
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error:
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unlock_page(page);
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return err;
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}
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const struct pipe_buf_operations page_cache_pipe_buf_ops = {
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.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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}
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static const struct pipe_buf_operations user_page_pipe_buf_ops = {
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.release = page_cache_pipe_buf_release,
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.try_steal = user_page_pipe_buf_try_steal,
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.get = generic_pipe_buf_get,
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};
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static void wakeup_pipe_readers(struct pipe_inode_info *pipe)
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{
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smp_mb();
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if (waitqueue_active(&pipe->rd_wait))
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wake_up_interruptible(&pipe->rd_wait);
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kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
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}
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/**
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* splice_to_pipe - fill passed data into a pipe
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* @pipe: pipe to fill
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* @spd: data to fill
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*
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* Description:
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* @spd contains a map of pages and len/offset tuples, along with
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* the struct pipe_buf_operations associated with these pages. This
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* function will link that data to the pipe.
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*
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*/
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ssize_t splice_to_pipe(struct pipe_inode_info *pipe,
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struct splice_pipe_desc *spd)
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{
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unsigned int spd_pages = spd->nr_pages;
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unsigned int tail = pipe->tail;
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unsigned int head = pipe->head;
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unsigned int mask = pipe->ring_size - 1;
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int ret = 0, page_nr = 0;
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if (!spd_pages)
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return 0;
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if (unlikely(!pipe->readers)) {
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send_sig(SIGPIPE, current, 0);
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ret = -EPIPE;
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goto out;
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}
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while (!pipe_full(head, tail, pipe->max_usage)) {
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struct pipe_buffer *buf = &pipe->bufs[head & mask];
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buf->page = spd->pages[page_nr];
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buf->offset = spd->partial[page_nr].offset;
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buf->len = spd->partial[page_nr].len;
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buf->private = spd->partial[page_nr].private;
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buf->ops = spd->ops;
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buf->flags = 0;
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head++;
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pipe->head = head;
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page_nr++;
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ret += buf->len;
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if (!--spd->nr_pages)
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break;
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}
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if (!ret)
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ret = -EAGAIN;
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out:
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while (page_nr < spd_pages)
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spd->spd_release(spd, page_nr++);
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return ret;
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}
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EXPORT_SYMBOL_GPL(splice_to_pipe);
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ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf)
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{
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unsigned int head = pipe->head;
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unsigned int tail = pipe->tail;
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unsigned int mask = pipe->ring_size - 1;
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int ret;
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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;
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} else {
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pipe->bufs[head & mask] = *buf;
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pipe->head = head + 1;
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return buf->len;
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}
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pipe_buf_release(pipe, buf);
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return ret;
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}
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EXPORT_SYMBOL(add_to_pipe);
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/*
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* Check if we need to grow the arrays holding pages and partial page
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* descriptions.
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*/
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int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd)
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{
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unsigned int 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;
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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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/**
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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
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* @flags: splice modifier flags
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*
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* Description:
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* Will read pages from given file and fill them into a pipe. Can be
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* used as long as it has more or less sane ->read_iter().
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*
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*/
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ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
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struct pipe_inode_info *pipe, size_t len,
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unsigned int flags)
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{
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struct iov_iter to;
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struct kiocb kiocb;
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unsigned int i_head;
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int ret;
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iov_iter_pipe(&to, READ, pipe, len);
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i_head = to.head;
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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 */
|
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/*
|
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* callers of ->splice_read() expect -EAGAIN on
|
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* "can't put anything in there", rather than -EFAULT.
|
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*/
|
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if (ret == -EFAULT)
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ret = -EAGAIN;
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}
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return ret;
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}
|
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EXPORT_SYMBOL(generic_file_splice_read);
|
|
|
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const struct pipe_buf_operations default_pipe_buf_ops = {
|
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.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 = {
|
|
.release = generic_pipe_buf_release,
|
|
.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,
|
|
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;
|
|
}
|