1457c8996SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only 25274f052SJens Axboe /* 35274f052SJens Axboe * "splice": joining two ropes together by interweaving their strands. 45274f052SJens Axboe * 55274f052SJens Axboe * This is the "extended pipe" functionality, where a pipe is used as 65274f052SJens Axboe * an arbitrary in-memory buffer. Think of a pipe as a small kernel 75274f052SJens Axboe * buffer that you can use to transfer data from one end to the other. 85274f052SJens Axboe * 95274f052SJens Axboe * The traditional unix read/write is extended with a "splice()" operation 105274f052SJens Axboe * that transfers data buffers to or from a pipe buffer. 115274f052SJens Axboe * 125274f052SJens Axboe * Named by Larry McVoy, original implementation from Linus, extended by 13c2058e06SJens Axboe * Jens to support splicing to files, network, direct splicing, etc and 14c2058e06SJens Axboe * fixing lots of bugs. 155274f052SJens Axboe * 160fe23479SJens Axboe * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> 17c2058e06SJens Axboe * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> 18c2058e06SJens Axboe * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> 195274f052SJens Axboe * 205274f052SJens Axboe */ 21be297968SChristoph Hellwig #include <linux/bvec.h> 225274f052SJens Axboe #include <linux/fs.h> 235274f052SJens Axboe #include <linux/file.h> 245274f052SJens Axboe #include <linux/pagemap.h> 25d6b29d7cSJens Axboe #include <linux/splice.h> 2608e552c6SKAMEZAWA Hiroyuki #include <linux/memcontrol.h> 275274f052SJens Axboe #include <linux/mm_inline.h> 285abc97aaSJens Axboe #include <linux/swap.h> 294f6f0bd2SJens Axboe #include <linux/writeback.h> 30630d9c47SPaul Gortmaker #include <linux/export.h> 314f6f0bd2SJens Axboe #include <linux/syscalls.h> 32912d35f8SJens Axboe #include <linux/uio.h> 33983652c6SChung-Chiang Cheng #include <linux/fsnotify.h> 3429ce2058SJames Morris #include <linux/security.h> 355a0e3ad6STejun Heo #include <linux/gfp.h> 3635f9c09fSEric Dumazet #include <linux/socket.h> 37174cd4b1SIngo Molnar #include <linux/sched/signal.h> 38174cd4b1SIngo Molnar 3906ae43f3SAl Viro #include "internal.h" 405274f052SJens Axboe 4183f9135bSJens Axboe /* 420f99fc51SJens Axboe * Splice doesn't support FMODE_NOWAIT. Since pipes may set this flag to 430f99fc51SJens Axboe * indicate they support non-blocking reads or writes, we must clear it 440f99fc51SJens Axboe * here if set to avoid blocking other users of this pipe if splice is 450f99fc51SJens Axboe * being done on it. 460f99fc51SJens Axboe */ 470f99fc51SJens Axboe static noinline void noinline pipe_clear_nowait(struct file *file) 480f99fc51SJens Axboe { 490f99fc51SJens Axboe fmode_t fmode = READ_ONCE(file->f_mode); 500f99fc51SJens Axboe 510f99fc51SJens Axboe do { 520f99fc51SJens Axboe if (!(fmode & FMODE_NOWAIT)) 530f99fc51SJens Axboe break; 540f99fc51SJens Axboe } while (!try_cmpxchg(&file->f_mode, &fmode, fmode & ~FMODE_NOWAIT)); 550f99fc51SJens Axboe } 560f99fc51SJens Axboe 570f99fc51SJens Axboe /* 5883f9135bSJens Axboe * Attempt to steal a page from a pipe buffer. This should perhaps go into 5983f9135bSJens Axboe * a vm helper function, it's already simplified quite a bit by the 6083f9135bSJens Axboe * addition of remove_mapping(). If success is returned, the caller may 6183f9135bSJens Axboe * attempt to reuse this page for another destination. 6283f9135bSJens Axboe */ 63c928f642SChristoph Hellwig static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe, 645abc97aaSJens Axboe struct pipe_buffer *buf) 655abc97aaSJens Axboe { 665100da38SMatthew Wilcox (Oracle) struct folio *folio = page_folio(buf->page); 679e94cd4fSJens Axboe struct address_space *mapping; 685abc97aaSJens Axboe 69b9ccad2eSMatthew Wilcox (Oracle) folio_lock(folio); 709e0267c2SJens Axboe 71b9ccad2eSMatthew Wilcox (Oracle) mapping = folio_mapping(folio); 729e94cd4fSJens Axboe if (mapping) { 73b9ccad2eSMatthew Wilcox (Oracle) WARN_ON(!folio_test_uptodate(folio)); 745abc97aaSJens Axboe 75ad8d6f0aSJens Axboe /* 769e94cd4fSJens Axboe * At least for ext2 with nobh option, we need to wait on 77b9ccad2eSMatthew Wilcox (Oracle) * writeback completing on this folio, since we'll remove it 789e94cd4fSJens Axboe * from the pagecache. Otherwise truncate wont wait on the 79b9ccad2eSMatthew Wilcox (Oracle) * folio, allowing the disk blocks to be reused by someone else 809e94cd4fSJens Axboe * before we actually wrote our data to them. fs corruption 819e94cd4fSJens Axboe * ensues. 82ad8d6f0aSJens Axboe */ 83b9ccad2eSMatthew Wilcox (Oracle) folio_wait_writeback(folio); 84ad8d6f0aSJens Axboe 85b9ccad2eSMatthew Wilcox (Oracle) if (folio_has_private(folio) && 86b9ccad2eSMatthew Wilcox (Oracle) !filemap_release_folio(folio, GFP_KERNEL)) 87ca39d651SJens Axboe goto out_unlock; 884f6f0bd2SJens Axboe 899e94cd4fSJens Axboe /* 909e94cd4fSJens Axboe * If we succeeded in removing the mapping, set LRU flag 919e94cd4fSJens Axboe * and return good. 929e94cd4fSJens Axboe */ 935100da38SMatthew Wilcox (Oracle) if (remove_mapping(mapping, folio)) { 941432873aSJens Axboe buf->flags |= PIPE_BUF_FLAG_LRU; 95c928f642SChristoph Hellwig return true; 965abc97aaSJens Axboe } 979e94cd4fSJens Axboe } 989e94cd4fSJens Axboe 999e94cd4fSJens Axboe /* 100b9ccad2eSMatthew Wilcox (Oracle) * Raced with truncate or failed to remove folio from current 1019e94cd4fSJens Axboe * address space, unlock and return failure. 1029e94cd4fSJens Axboe */ 103ca39d651SJens Axboe out_unlock: 104b9ccad2eSMatthew Wilcox (Oracle) folio_unlock(folio); 105c928f642SChristoph Hellwig return false; 1069e94cd4fSJens Axboe } 1075abc97aaSJens Axboe 10876ad4d11SJens Axboe static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, 1095274f052SJens Axboe struct pipe_buffer *buf) 1105274f052SJens Axboe { 11109cbfeafSKirill A. Shutemov put_page(buf->page); 1121432873aSJens Axboe buf->flags &= ~PIPE_BUF_FLAG_LRU; 1135274f052SJens Axboe } 1145274f052SJens Axboe 1150845718dSJens Axboe /* 1160845718dSJens Axboe * Check whether the contents of buf is OK to access. Since the content 1170845718dSJens Axboe * is a page cache page, IO may be in flight. 1180845718dSJens Axboe */ 119cac36bb0SJens Axboe static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, 1205274f052SJens Axboe struct pipe_buffer *buf) 1215274f052SJens Axboe { 1225274f052SJens Axboe struct page *page = buf->page; 12349d0b21bSJens Axboe int err; 1245274f052SJens Axboe 1255274f052SJens Axboe if (!PageUptodate(page)) { 12649d0b21bSJens Axboe lock_page(page); 1275274f052SJens Axboe 12849d0b21bSJens Axboe /* 12949d0b21bSJens Axboe * Page got truncated/unhashed. This will cause a 0-byte 13073d62d83SIngo Molnar * splice, if this is the first page. 13149d0b21bSJens Axboe */ 1325274f052SJens Axboe if (!page->mapping) { 13349d0b21bSJens Axboe err = -ENODATA; 13449d0b21bSJens Axboe goto error; 1355274f052SJens Axboe } 1365274f052SJens Axboe 13749d0b21bSJens Axboe /* 13873d62d83SIngo Molnar * Uh oh, read-error from disk. 13949d0b21bSJens Axboe */ 14049d0b21bSJens Axboe if (!PageUptodate(page)) { 14149d0b21bSJens Axboe err = -EIO; 14249d0b21bSJens Axboe goto error; 14349d0b21bSJens Axboe } 14449d0b21bSJens Axboe 14549d0b21bSJens Axboe /* 146f84d7519SJens Axboe * Page is ok afterall, we are done. 14749d0b21bSJens Axboe */ 14849d0b21bSJens Axboe unlock_page(page); 14949d0b21bSJens Axboe } 15049d0b21bSJens Axboe 151f84d7519SJens Axboe return 0; 15249d0b21bSJens Axboe error: 15349d0b21bSJens Axboe unlock_page(page); 154f84d7519SJens Axboe return err; 15570524490SJens Axboe } 15670524490SJens Axboe 157708e3508SHugh Dickins const struct pipe_buf_operations page_cache_pipe_buf_ops = { 158cac36bb0SJens Axboe .confirm = page_cache_pipe_buf_confirm, 1595274f052SJens Axboe .release = page_cache_pipe_buf_release, 160c928f642SChristoph Hellwig .try_steal = page_cache_pipe_buf_try_steal, 161f84d7519SJens Axboe .get = generic_pipe_buf_get, 1625274f052SJens Axboe }; 1635274f052SJens Axboe 164c928f642SChristoph Hellwig static bool user_page_pipe_buf_try_steal(struct pipe_inode_info *pipe, 165912d35f8SJens Axboe struct pipe_buffer *buf) 166912d35f8SJens Axboe { 1677afa6fd0SJens Axboe if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) 168c928f642SChristoph Hellwig return false; 1697afa6fd0SJens Axboe 1701432873aSJens Axboe buf->flags |= PIPE_BUF_FLAG_LRU; 171c928f642SChristoph Hellwig return generic_pipe_buf_try_steal(pipe, buf); 172912d35f8SJens Axboe } 173912d35f8SJens Axboe 174d4c3cca9SEric Dumazet static const struct pipe_buf_operations user_page_pipe_buf_ops = { 175912d35f8SJens Axboe .release = page_cache_pipe_buf_release, 176c928f642SChristoph Hellwig .try_steal = user_page_pipe_buf_try_steal, 177f84d7519SJens Axboe .get = generic_pipe_buf_get, 178912d35f8SJens Axboe }; 179912d35f8SJens Axboe 180825cdcb1SNamhyung Kim static void wakeup_pipe_readers(struct pipe_inode_info *pipe) 181825cdcb1SNamhyung Kim { 182825cdcb1SNamhyung Kim smp_mb(); 1830ddad21dSLinus Torvalds if (waitqueue_active(&pipe->rd_wait)) 1840ddad21dSLinus Torvalds wake_up_interruptible(&pipe->rd_wait); 185825cdcb1SNamhyung Kim kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); 186825cdcb1SNamhyung Kim } 187825cdcb1SNamhyung Kim 188932cc6d4SJens Axboe /** 189932cc6d4SJens Axboe * splice_to_pipe - fill passed data into a pipe 190932cc6d4SJens Axboe * @pipe: pipe to fill 191932cc6d4SJens Axboe * @spd: data to fill 192932cc6d4SJens Axboe * 193932cc6d4SJens Axboe * Description: 19479685b8dSRandy Dunlap * @spd contains a map of pages and len/offset tuples, along with 195932cc6d4SJens Axboe * the struct pipe_buf_operations associated with these pages. This 196932cc6d4SJens Axboe * function will link that data to the pipe. 197932cc6d4SJens Axboe * 19883f9135bSJens Axboe */ 199d6b29d7cSJens Axboe ssize_t splice_to_pipe(struct pipe_inode_info *pipe, 200912d35f8SJens Axboe struct splice_pipe_desc *spd) 2015274f052SJens Axboe { 20200de00bdSJens Axboe unsigned int spd_pages = spd->nr_pages; 2038cefc107SDavid Howells unsigned int tail = pipe->tail; 2048cefc107SDavid Howells unsigned int head = pipe->head; 2058cefc107SDavid Howells unsigned int mask = pipe->ring_size - 1; 2068924feffSAl Viro int ret = 0, page_nr = 0; 2075274f052SJens Axboe 208d6785d91SRabin Vincent if (!spd_pages) 209d6785d91SRabin Vincent return 0; 210d6785d91SRabin Vincent 2118924feffSAl Viro if (unlikely(!pipe->readers)) { 2125274f052SJens Axboe send_sig(SIGPIPE, current, 0); 2135274f052SJens Axboe ret = -EPIPE; 2148924feffSAl Viro goto out; 2155274f052SJens Axboe } 2165274f052SJens Axboe 2176718b6f8SDavid Howells while (!pipe_full(head, tail, pipe->max_usage)) { 2188cefc107SDavid Howells struct pipe_buffer *buf = &pipe->bufs[head & mask]; 2195274f052SJens Axboe 220912d35f8SJens Axboe buf->page = spd->pages[page_nr]; 221912d35f8SJens Axboe buf->offset = spd->partial[page_nr].offset; 222912d35f8SJens Axboe buf->len = spd->partial[page_nr].len; 223497f9625SJens Axboe buf->private = spd->partial[page_nr].private; 224912d35f8SJens Axboe buf->ops = spd->ops; 2255a81e6a1SMiklos Szeredi buf->flags = 0; 2267afa6fd0SJens Axboe 2278cefc107SDavid Howells head++; 2288cefc107SDavid Howells pipe->head = head; 229912d35f8SJens Axboe page_nr++; 230912d35f8SJens Axboe ret += buf->len; 231912d35f8SJens Axboe 232912d35f8SJens Axboe if (!--spd->nr_pages) 2335274f052SJens Axboe break; 2345274f052SJens Axboe } 2355274f052SJens Axboe 23629e35094SLinus Torvalds if (!ret) 23729e35094SLinus Torvalds ret = -EAGAIN; 23829e35094SLinus Torvalds 2398924feffSAl Viro out: 24000de00bdSJens Axboe while (page_nr < spd_pages) 241bbdfc2f7SJens Axboe spd->spd_release(spd, page_nr++); 2425274f052SJens Axboe 2435274f052SJens Axboe return ret; 2445274f052SJens Axboe } 2452b514574SHannes Frederic Sowa EXPORT_SYMBOL_GPL(splice_to_pipe); 2465274f052SJens Axboe 24779fddc4eSAl Viro ssize_t add_to_pipe(struct pipe_inode_info *pipe, struct pipe_buffer *buf) 24879fddc4eSAl Viro { 2498cefc107SDavid Howells unsigned int head = pipe->head; 2508cefc107SDavid Howells unsigned int tail = pipe->tail; 2518cefc107SDavid Howells unsigned int mask = pipe->ring_size - 1; 25279fddc4eSAl Viro int ret; 25379fddc4eSAl Viro 25479fddc4eSAl Viro if (unlikely(!pipe->readers)) { 25579fddc4eSAl Viro send_sig(SIGPIPE, current, 0); 25679fddc4eSAl Viro ret = -EPIPE; 2576718b6f8SDavid Howells } else if (pipe_full(head, tail, pipe->max_usage)) { 25879fddc4eSAl Viro ret = -EAGAIN; 25979fddc4eSAl Viro } else { 2608cefc107SDavid Howells pipe->bufs[head & mask] = *buf; 2618cefc107SDavid Howells pipe->head = head + 1; 26279fddc4eSAl Viro return buf->len; 26379fddc4eSAl Viro } 264a779638cSMiklos Szeredi pipe_buf_release(pipe, buf); 26579fddc4eSAl Viro return ret; 26679fddc4eSAl Viro } 26779fddc4eSAl Viro EXPORT_SYMBOL(add_to_pipe); 26879fddc4eSAl Viro 26935f3d14dSJens Axboe /* 27035f3d14dSJens Axboe * Check if we need to grow the arrays holding pages and partial page 27135f3d14dSJens Axboe * descriptions. 27235f3d14dSJens Axboe */ 273047fe360SEric Dumazet int splice_grow_spd(const struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) 27435f3d14dSJens Axboe { 2756718b6f8SDavid Howells unsigned int max_usage = READ_ONCE(pipe->max_usage); 276047fe360SEric Dumazet 2778cefc107SDavid Howells spd->nr_pages_max = max_usage; 2788cefc107SDavid Howells if (max_usage <= PIPE_DEF_BUFFERS) 27935f3d14dSJens Axboe return 0; 28035f3d14dSJens Axboe 2818cefc107SDavid Howells spd->pages = kmalloc_array(max_usage, sizeof(struct page *), GFP_KERNEL); 2828cefc107SDavid Howells spd->partial = kmalloc_array(max_usage, sizeof(struct partial_page), 2836da2ec56SKees Cook GFP_KERNEL); 28435f3d14dSJens Axboe 28535f3d14dSJens Axboe if (spd->pages && spd->partial) 28635f3d14dSJens Axboe return 0; 28735f3d14dSJens Axboe 28835f3d14dSJens Axboe kfree(spd->pages); 28935f3d14dSJens Axboe kfree(spd->partial); 29035f3d14dSJens Axboe return -ENOMEM; 29135f3d14dSJens Axboe } 29235f3d14dSJens Axboe 293047fe360SEric Dumazet void splice_shrink_spd(struct splice_pipe_desc *spd) 29435f3d14dSJens Axboe { 295047fe360SEric Dumazet if (spd->nr_pages_max <= PIPE_DEF_BUFFERS) 29635f3d14dSJens Axboe return; 29735f3d14dSJens Axboe 29835f3d14dSJens Axboe kfree(spd->pages); 29935f3d14dSJens Axboe kfree(spd->partial); 30035f3d14dSJens Axboe } 30135f3d14dSJens Axboe 30233b3b041SDavid Howells /* 303*69df79a4SDavid Howells * Copy data from a file into pages and then splice those into the output pipe. 30433b3b041SDavid Howells */ 305*69df79a4SDavid Howells ssize_t copy_splice_read(struct file *in, loff_t *ppos, 30633b3b041SDavid Howells struct pipe_inode_info *pipe, 30733b3b041SDavid Howells size_t len, unsigned int flags) 30833b3b041SDavid Howells { 30933b3b041SDavid Howells struct iov_iter to; 31033b3b041SDavid Howells struct bio_vec *bv; 31133b3b041SDavid Howells struct kiocb kiocb; 31233b3b041SDavid Howells struct page **pages; 31333b3b041SDavid Howells ssize_t ret; 31433b3b041SDavid Howells size_t used, npages, chunk, remain, reclaim; 31533b3b041SDavid Howells int i; 31633b3b041SDavid Howells 31733b3b041SDavid Howells /* Work out how much data we can actually add into the pipe */ 31833b3b041SDavid Howells used = pipe_occupancy(pipe->head, pipe->tail); 31933b3b041SDavid Howells npages = max_t(ssize_t, pipe->max_usage - used, 0); 32033b3b041SDavid Howells len = min_t(size_t, len, npages * PAGE_SIZE); 32133b3b041SDavid Howells npages = DIV_ROUND_UP(len, PAGE_SIZE); 32233b3b041SDavid Howells 32333b3b041SDavid Howells bv = kzalloc(array_size(npages, sizeof(bv[0])) + 32433b3b041SDavid Howells array_size(npages, sizeof(struct page *)), GFP_KERNEL); 32533b3b041SDavid Howells if (!bv) 32633b3b041SDavid Howells return -ENOMEM; 32733b3b041SDavid Howells 32833b3b041SDavid Howells pages = (void *)(bv + npages); 32933b3b041SDavid Howells npages = alloc_pages_bulk_array(GFP_USER, npages, pages); 33033b3b041SDavid Howells if (!npages) { 33133b3b041SDavid Howells kfree(bv); 33233b3b041SDavid Howells return -ENOMEM; 33333b3b041SDavid Howells } 33433b3b041SDavid Howells 33533b3b041SDavid Howells remain = len = min_t(size_t, len, npages * PAGE_SIZE); 33633b3b041SDavid Howells 33733b3b041SDavid Howells for (i = 0; i < npages; i++) { 33833b3b041SDavid Howells chunk = min_t(size_t, PAGE_SIZE, remain); 33933b3b041SDavid Howells bv[i].bv_page = pages[i]; 34033b3b041SDavid Howells bv[i].bv_offset = 0; 34133b3b041SDavid Howells bv[i].bv_len = chunk; 34233b3b041SDavid Howells remain -= chunk; 34333b3b041SDavid Howells } 34433b3b041SDavid Howells 34533b3b041SDavid Howells /* Do the I/O */ 34633b3b041SDavid Howells iov_iter_bvec(&to, ITER_DEST, bv, npages, len); 34733b3b041SDavid Howells init_sync_kiocb(&kiocb, in); 34833b3b041SDavid Howells kiocb.ki_pos = *ppos; 34933b3b041SDavid Howells ret = call_read_iter(in, &kiocb, &to); 35033b3b041SDavid Howells 35133b3b041SDavid Howells reclaim = npages * PAGE_SIZE; 35233b3b041SDavid Howells remain = 0; 35333b3b041SDavid Howells if (ret > 0) { 35433b3b041SDavid Howells reclaim -= ret; 35533b3b041SDavid Howells remain = ret; 35633b3b041SDavid Howells *ppos = kiocb.ki_pos; 35733b3b041SDavid Howells file_accessed(in); 35833b3b041SDavid Howells } else if (ret < 0) { 35933b3b041SDavid Howells /* 36033b3b041SDavid Howells * callers of ->splice_read() expect -EAGAIN on 36133b3b041SDavid Howells * "can't put anything in there", rather than -EFAULT. 36233b3b041SDavid Howells */ 36333b3b041SDavid Howells if (ret == -EFAULT) 36433b3b041SDavid Howells ret = -EAGAIN; 36533b3b041SDavid Howells } 36633b3b041SDavid Howells 36733b3b041SDavid Howells /* Free any pages that didn't get touched at all. */ 36833b3b041SDavid Howells reclaim /= PAGE_SIZE; 36933b3b041SDavid Howells if (reclaim) { 37033b3b041SDavid Howells npages -= reclaim; 37133b3b041SDavid Howells release_pages(pages + npages, reclaim); 37233b3b041SDavid Howells } 37333b3b041SDavid Howells 37433b3b041SDavid Howells /* Push the remaining pages into the pipe. */ 37533b3b041SDavid Howells for (i = 0; i < npages; i++) { 37633b3b041SDavid Howells struct pipe_buffer *buf = pipe_head_buf(pipe); 37733b3b041SDavid Howells 37833b3b041SDavid Howells chunk = min_t(size_t, remain, PAGE_SIZE); 37933b3b041SDavid Howells *buf = (struct pipe_buffer) { 38033b3b041SDavid Howells .ops = &default_pipe_buf_ops, 38133b3b041SDavid Howells .page = bv[i].bv_page, 38233b3b041SDavid Howells .offset = 0, 38333b3b041SDavid Howells .len = chunk, 38433b3b041SDavid Howells }; 38533b3b041SDavid Howells pipe->head++; 38633b3b041SDavid Howells remain -= chunk; 38733b3b041SDavid Howells } 38833b3b041SDavid Howells 38933b3b041SDavid Howells kfree(bv); 39033b3b041SDavid Howells return ret; 39133b3b041SDavid Howells } 392*69df79a4SDavid Howells EXPORT_SYMBOL(copy_splice_read); 39333b3b041SDavid Howells 39483f9135bSJens Axboe /** 39583f9135bSJens Axboe * generic_file_splice_read - splice data from file to a pipe 39683f9135bSJens Axboe * @in: file to splice from 397932cc6d4SJens Axboe * @ppos: position in @in 39883f9135bSJens Axboe * @pipe: pipe to splice to 39983f9135bSJens Axboe * @len: number of bytes to splice 40083f9135bSJens Axboe * @flags: splice modifier flags 40183f9135bSJens Axboe * 402932cc6d4SJens Axboe * Description: 403932cc6d4SJens Axboe * Will read pages from given file and fill them into a pipe. Can be 40482c156f8SAl Viro * used as long as it has more or less sane ->read_iter(). 405932cc6d4SJens Axboe * 40683f9135bSJens Axboe */ 407cbb7e577SJens Axboe ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, 408cbb7e577SJens Axboe struct pipe_inode_info *pipe, size_t len, 409cbb7e577SJens Axboe unsigned int flags) 4105274f052SJens Axboe { 41182c156f8SAl Viro struct iov_iter to; 41282c156f8SAl Viro struct kiocb kiocb; 4138cefc107SDavid Howells int ret; 414be64f884SBoaz Harrosh 415de4eda9dSAl Viro iov_iter_pipe(&to, ITER_DEST, pipe, len); 41682c156f8SAl Viro init_sync_kiocb(&kiocb, in); 41782c156f8SAl Viro kiocb.ki_pos = *ppos; 418bb7462b6SMiklos Szeredi ret = call_read_iter(in, &kiocb, &to); 419723590edSMiklos Szeredi if (ret > 0) { 42082c156f8SAl Viro *ppos = kiocb.ki_pos; 421723590edSMiklos Szeredi file_accessed(in); 42282c156f8SAl Viro } else if (ret < 0) { 4230d964934SAl Viro /* free what was emitted */ 4240d964934SAl Viro pipe_discard_from(pipe, to.start_head); 42582c156f8SAl Viro /* 42682c156f8SAl Viro * callers of ->splice_read() expect -EAGAIN on 42782c156f8SAl Viro * "can't put anything in there", rather than -EFAULT. 42882c156f8SAl Viro */ 42982c156f8SAl Viro if (ret == -EFAULT) 43082c156f8SAl Viro ret = -EAGAIN; 431723590edSMiklos Szeredi } 4325274f052SJens Axboe 4335274f052SJens Axboe return ret; 4345274f052SJens Axboe } 435059a8f37SJens Axboe EXPORT_SYMBOL(generic_file_splice_read); 436059a8f37SJens Axboe 437241699cdSAl Viro const struct pipe_buf_operations default_pipe_buf_ops = { 4386818173bSMiklos Szeredi .release = generic_pipe_buf_release, 439c928f642SChristoph Hellwig .try_steal = generic_pipe_buf_try_steal, 4406818173bSMiklos Szeredi .get = generic_pipe_buf_get, 4416818173bSMiklos Szeredi }; 4426818173bSMiklos Szeredi 44328a625cbSMiklos Szeredi /* Pipe buffer operations for a socket and similar. */ 44428a625cbSMiklos Szeredi const struct pipe_buf_operations nosteal_pipe_buf_ops = { 44528a625cbSMiklos Szeredi .release = generic_pipe_buf_release, 44628a625cbSMiklos Szeredi .get = generic_pipe_buf_get, 44728a625cbSMiklos Szeredi }; 44828a625cbSMiklos Szeredi EXPORT_SYMBOL(nosteal_pipe_buf_ops); 44928a625cbSMiklos Szeredi 4505274f052SJens Axboe /* 4514f6f0bd2SJens Axboe * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' 452016b661eSJens Axboe * using sendpage(). Return the number of bytes sent. 4535274f052SJens Axboe */ 45476ad4d11SJens Axboe static int pipe_to_sendpage(struct pipe_inode_info *pipe, 4555274f052SJens Axboe struct pipe_buffer *buf, struct splice_desc *sd) 4565274f052SJens Axboe { 4576a14b90bSJens Axboe struct file *file = sd->u.file; 4585274f052SJens Axboe loff_t pos = sd->pos; 459a8adbe37SMichał Mirosław int more; 4605274f052SJens Axboe 46172c2d531SAl Viro if (!likely(file->f_op->sendpage)) 462a8adbe37SMichał Mirosław return -EINVAL; 463a8adbe37SMichał Mirosław 46435f9c09fSEric Dumazet more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; 465ae62ca7bSEric Dumazet 4668cefc107SDavid Howells if (sd->len < sd->total_len && 4678cefc107SDavid Howells pipe_occupancy(pipe->head, pipe->tail) > 1) 46835f9c09fSEric Dumazet more |= MSG_SENDPAGE_NOTLAST; 469ae62ca7bSEric Dumazet 470a8adbe37SMichał Mirosław return file->f_op->sendpage(file, buf->page, buf->offset, 471f84d7519SJens Axboe sd->len, &pos, more); 4725274f052SJens Axboe } 4735274f052SJens Axboe 474b3c2d2ddSMiklos Szeredi static void wakeup_pipe_writers(struct pipe_inode_info *pipe) 475b3c2d2ddSMiklos Szeredi { 476b3c2d2ddSMiklos Szeredi smp_mb(); 4770ddad21dSLinus Torvalds if (waitqueue_active(&pipe->wr_wait)) 4780ddad21dSLinus Torvalds wake_up_interruptible(&pipe->wr_wait); 479b3c2d2ddSMiklos Szeredi kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); 480b3c2d2ddSMiklos Szeredi } 481b3c2d2ddSMiklos Szeredi 482b3c2d2ddSMiklos Szeredi /** 483b3c2d2ddSMiklos Szeredi * splice_from_pipe_feed - feed available data from a pipe to a file 484b3c2d2ddSMiklos Szeredi * @pipe: pipe to splice from 485b3c2d2ddSMiklos Szeredi * @sd: information to @actor 486b3c2d2ddSMiklos Szeredi * @actor: handler that splices the data 487b3c2d2ddSMiklos Szeredi * 488b3c2d2ddSMiklos Szeredi * Description: 489b3c2d2ddSMiklos Szeredi * This function loops over the pipe and calls @actor to do the 490b3c2d2ddSMiklos Szeredi * actual moving of a single struct pipe_buffer to the desired 491b3c2d2ddSMiklos Szeredi * destination. It returns when there's no more buffers left in 492b3c2d2ddSMiklos Szeredi * the pipe or if the requested number of bytes (@sd->total_len) 493b3c2d2ddSMiklos Szeredi * have been copied. It returns a positive number (one) if the 494b3c2d2ddSMiklos Szeredi * pipe needs to be filled with more data, zero if the required 495b3c2d2ddSMiklos Szeredi * number of bytes have been copied and -errno on error. 496b3c2d2ddSMiklos Szeredi * 497b3c2d2ddSMiklos Szeredi * This, together with splice_from_pipe_{begin,end,next}, may be 498b3c2d2ddSMiklos Szeredi * used to implement the functionality of __splice_from_pipe() when 499b3c2d2ddSMiklos Szeredi * locking is required around copying the pipe buffers to the 500b3c2d2ddSMiklos Szeredi * destination. 501b3c2d2ddSMiklos Szeredi */ 50296f9bc8fSAl Viro static int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, 503b3c2d2ddSMiklos Szeredi splice_actor *actor) 504b3c2d2ddSMiklos Szeredi { 5058cefc107SDavid Howells unsigned int head = pipe->head; 5068cefc107SDavid Howells unsigned int tail = pipe->tail; 5078cefc107SDavid Howells unsigned int mask = pipe->ring_size - 1; 508b3c2d2ddSMiklos Szeredi int ret; 509b3c2d2ddSMiklos Szeredi 510ec057595SLinus Torvalds while (!pipe_empty(head, tail)) { 5118cefc107SDavid Howells struct pipe_buffer *buf = &pipe->bufs[tail & mask]; 512b3c2d2ddSMiklos Szeredi 513b3c2d2ddSMiklos Szeredi sd->len = buf->len; 514b3c2d2ddSMiklos Szeredi if (sd->len > sd->total_len) 515b3c2d2ddSMiklos Szeredi sd->len = sd->total_len; 516b3c2d2ddSMiklos Szeredi 517fba597dbSMiklos Szeredi ret = pipe_buf_confirm(pipe, buf); 518a8adbe37SMichał Mirosław if (unlikely(ret)) { 519b3c2d2ddSMiklos Szeredi if (ret == -ENODATA) 520b3c2d2ddSMiklos Szeredi ret = 0; 521b3c2d2ddSMiklos Szeredi return ret; 522b3c2d2ddSMiklos Szeredi } 523a8adbe37SMichał Mirosław 524a8adbe37SMichał Mirosław ret = actor(pipe, buf, sd); 525a8adbe37SMichał Mirosław if (ret <= 0) 526a8adbe37SMichał Mirosław return ret; 527a8adbe37SMichał Mirosław 528b3c2d2ddSMiklos Szeredi buf->offset += ret; 529b3c2d2ddSMiklos Szeredi buf->len -= ret; 530b3c2d2ddSMiklos Szeredi 531b3c2d2ddSMiklos Szeredi sd->num_spliced += ret; 532b3c2d2ddSMiklos Szeredi sd->len -= ret; 533b3c2d2ddSMiklos Szeredi sd->pos += ret; 534b3c2d2ddSMiklos Szeredi sd->total_len -= ret; 535b3c2d2ddSMiklos Szeredi 536b3c2d2ddSMiklos Szeredi if (!buf->len) { 537a779638cSMiklos Szeredi pipe_buf_release(pipe, buf); 5388cefc107SDavid Howells tail++; 5398cefc107SDavid Howells pipe->tail = tail; 5406447a3cfSAl Viro if (pipe->files) 541b3c2d2ddSMiklos Szeredi sd->need_wakeup = true; 542b3c2d2ddSMiklos Szeredi } 543b3c2d2ddSMiklos Szeredi 544b3c2d2ddSMiklos Szeredi if (!sd->total_len) 545b3c2d2ddSMiklos Szeredi return 0; 546b3c2d2ddSMiklos Szeredi } 547b3c2d2ddSMiklos Szeredi 548b3c2d2ddSMiklos Szeredi return 1; 549b3c2d2ddSMiklos Szeredi } 550b3c2d2ddSMiklos Szeredi 551d1a819a2SLinus Torvalds /* We know we have a pipe buffer, but maybe it's empty? */ 552d1a819a2SLinus Torvalds static inline bool eat_empty_buffer(struct pipe_inode_info *pipe) 553d1a819a2SLinus Torvalds { 554d1a819a2SLinus Torvalds unsigned int tail = pipe->tail; 555d1a819a2SLinus Torvalds unsigned int mask = pipe->ring_size - 1; 556d1a819a2SLinus Torvalds struct pipe_buffer *buf = &pipe->bufs[tail & mask]; 557d1a819a2SLinus Torvalds 558d1a819a2SLinus Torvalds if (unlikely(!buf->len)) { 559d1a819a2SLinus Torvalds pipe_buf_release(pipe, buf); 560d1a819a2SLinus Torvalds pipe->tail = tail+1; 561d1a819a2SLinus Torvalds return true; 562d1a819a2SLinus Torvalds } 563d1a819a2SLinus Torvalds 564d1a819a2SLinus Torvalds return false; 565d1a819a2SLinus Torvalds } 566d1a819a2SLinus Torvalds 567b3c2d2ddSMiklos Szeredi /** 568b3c2d2ddSMiklos Szeredi * splice_from_pipe_next - wait for some data to splice from 569b3c2d2ddSMiklos Szeredi * @pipe: pipe to splice from 570b3c2d2ddSMiklos Szeredi * @sd: information about the splice operation 571b3c2d2ddSMiklos Szeredi * 572b3c2d2ddSMiklos Szeredi * Description: 573b3c2d2ddSMiklos Szeredi * This function will wait for some data and return a positive 574b3c2d2ddSMiklos Szeredi * value (one) if pipe buffers are available. It will return zero 575b3c2d2ddSMiklos Szeredi * or -errno if no more data needs to be spliced. 576b3c2d2ddSMiklos Szeredi */ 57796f9bc8fSAl Viro static int splice_from_pipe_next(struct pipe_inode_info *pipe, struct splice_desc *sd) 578b3c2d2ddSMiklos Szeredi { 579c725bfceSJan Kara /* 580c725bfceSJan Kara * Check for signal early to make process killable when there are 581c725bfceSJan Kara * always buffers available 582c725bfceSJan Kara */ 583c725bfceSJan Kara if (signal_pending(current)) 584c725bfceSJan Kara return -ERESTARTSYS; 585c725bfceSJan Kara 586d1a819a2SLinus Torvalds repeat: 5878cefc107SDavid Howells while (pipe_empty(pipe->head, pipe->tail)) { 588b3c2d2ddSMiklos Szeredi if (!pipe->writers) 589b3c2d2ddSMiklos Szeredi return 0; 590b3c2d2ddSMiklos Szeredi 591a28c8b9dSLinus Torvalds if (sd->num_spliced) 592b3c2d2ddSMiklos Szeredi return 0; 593b3c2d2ddSMiklos Szeredi 594b3c2d2ddSMiklos Szeredi if (sd->flags & SPLICE_F_NONBLOCK) 595b3c2d2ddSMiklos Szeredi return -EAGAIN; 596b3c2d2ddSMiklos Szeredi 597b3c2d2ddSMiklos Szeredi if (signal_pending(current)) 598b3c2d2ddSMiklos Szeredi return -ERESTARTSYS; 599b3c2d2ddSMiklos Szeredi 600b3c2d2ddSMiklos Szeredi if (sd->need_wakeup) { 601b3c2d2ddSMiklos Szeredi wakeup_pipe_writers(pipe); 602b3c2d2ddSMiklos Szeredi sd->need_wakeup = false; 603b3c2d2ddSMiklos Szeredi } 604b3c2d2ddSMiklos Szeredi 605472e5b05SLinus Torvalds pipe_wait_readable(pipe); 606b3c2d2ddSMiklos Szeredi } 607b3c2d2ddSMiklos Szeredi 608d1a819a2SLinus Torvalds if (eat_empty_buffer(pipe)) 609d1a819a2SLinus Torvalds goto repeat; 610d1a819a2SLinus Torvalds 611b3c2d2ddSMiklos Szeredi return 1; 612b3c2d2ddSMiklos Szeredi } 613b3c2d2ddSMiklos Szeredi 614b3c2d2ddSMiklos Szeredi /** 615b3c2d2ddSMiklos Szeredi * splice_from_pipe_begin - start splicing from pipe 616b80901bbSRandy Dunlap * @sd: information about the splice operation 617b3c2d2ddSMiklos Szeredi * 618b3c2d2ddSMiklos Szeredi * Description: 619b3c2d2ddSMiklos Szeredi * This function should be called before a loop containing 620b3c2d2ddSMiklos Szeredi * splice_from_pipe_next() and splice_from_pipe_feed() to 621b3c2d2ddSMiklos Szeredi * initialize the necessary fields of @sd. 622b3c2d2ddSMiklos Szeredi */ 62396f9bc8fSAl Viro static void splice_from_pipe_begin(struct splice_desc *sd) 624b3c2d2ddSMiklos Szeredi { 625b3c2d2ddSMiklos Szeredi sd->num_spliced = 0; 626b3c2d2ddSMiklos Szeredi sd->need_wakeup = false; 627b3c2d2ddSMiklos Szeredi } 628b3c2d2ddSMiklos Szeredi 629b3c2d2ddSMiklos Szeredi /** 630b3c2d2ddSMiklos Szeredi * splice_from_pipe_end - finish splicing from pipe 631b3c2d2ddSMiklos Szeredi * @pipe: pipe to splice from 632b3c2d2ddSMiklos Szeredi * @sd: information about the splice operation 633b3c2d2ddSMiklos Szeredi * 634b3c2d2ddSMiklos Szeredi * Description: 635b3c2d2ddSMiklos Szeredi * This function will wake up pipe writers if necessary. It should 636b3c2d2ddSMiklos Szeredi * be called after a loop containing splice_from_pipe_next() and 637b3c2d2ddSMiklos Szeredi * splice_from_pipe_feed(). 638b3c2d2ddSMiklos Szeredi */ 63996f9bc8fSAl Viro static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_desc *sd) 640b3c2d2ddSMiklos Szeredi { 641b3c2d2ddSMiklos Szeredi if (sd->need_wakeup) 642b3c2d2ddSMiklos Szeredi wakeup_pipe_writers(pipe); 643b3c2d2ddSMiklos Szeredi } 644b3c2d2ddSMiklos Szeredi 645932cc6d4SJens Axboe /** 646932cc6d4SJens Axboe * __splice_from_pipe - splice data from a pipe to given actor 647932cc6d4SJens Axboe * @pipe: pipe to splice from 648932cc6d4SJens Axboe * @sd: information to @actor 649932cc6d4SJens Axboe * @actor: handler that splices the data 650932cc6d4SJens Axboe * 651932cc6d4SJens Axboe * Description: 652932cc6d4SJens Axboe * This function does little more than loop over the pipe and call 653932cc6d4SJens Axboe * @actor to do the actual moving of a single struct pipe_buffer to 654932cc6d4SJens Axboe * the desired destination. See pipe_to_file, pipe_to_sendpage, or 655932cc6d4SJens Axboe * pipe_to_user. 656932cc6d4SJens Axboe * 65783f9135bSJens Axboe */ 658c66ab6faSJens Axboe ssize_t __splice_from_pipe(struct pipe_inode_info *pipe, struct splice_desc *sd, 659c66ab6faSJens Axboe splice_actor *actor) 6605274f052SJens Axboe { 661b3c2d2ddSMiklos Szeredi int ret; 6625274f052SJens Axboe 663b3c2d2ddSMiklos Szeredi splice_from_pipe_begin(sd); 664b3c2d2ddSMiklos Szeredi do { 665c2489e07SJan Kara cond_resched(); 666b3c2d2ddSMiklos Szeredi ret = splice_from_pipe_next(pipe, sd); 667b3c2d2ddSMiklos Szeredi if (ret > 0) 668b3c2d2ddSMiklos Szeredi ret = splice_from_pipe_feed(pipe, sd, actor); 669b3c2d2ddSMiklos Szeredi } while (ret > 0); 670b3c2d2ddSMiklos Szeredi splice_from_pipe_end(pipe, sd); 6715274f052SJens Axboe 672b3c2d2ddSMiklos Szeredi return sd->num_spliced ? sd->num_spliced : ret; 6735274f052SJens Axboe } 67440bee44eSMark Fasheh EXPORT_SYMBOL(__splice_from_pipe); 6755274f052SJens Axboe 676932cc6d4SJens Axboe /** 677932cc6d4SJens Axboe * splice_from_pipe - splice data from a pipe to a file 678932cc6d4SJens Axboe * @pipe: pipe to splice from 679932cc6d4SJens Axboe * @out: file to splice to 680932cc6d4SJens Axboe * @ppos: position in @out 681932cc6d4SJens Axboe * @len: how many bytes to splice 682932cc6d4SJens Axboe * @flags: splice modifier flags 683932cc6d4SJens Axboe * @actor: handler that splices the data 684932cc6d4SJens Axboe * 685932cc6d4SJens Axboe * Description: 6862933970bSMiklos Szeredi * See __splice_from_pipe. This function locks the pipe inode, 687932cc6d4SJens Axboe * otherwise it's identical to __splice_from_pipe(). 688932cc6d4SJens Axboe * 689932cc6d4SJens Axboe */ 6906da61809SMark Fasheh ssize_t splice_from_pipe(struct pipe_inode_info *pipe, struct file *out, 6916da61809SMark Fasheh loff_t *ppos, size_t len, unsigned int flags, 6926da61809SMark Fasheh splice_actor *actor) 6936da61809SMark Fasheh { 6946da61809SMark Fasheh ssize_t ret; 695c66ab6faSJens Axboe struct splice_desc sd = { 696c66ab6faSJens Axboe .total_len = len, 697c66ab6faSJens Axboe .flags = flags, 698c66ab6faSJens Axboe .pos = *ppos, 6996a14b90bSJens Axboe .u.file = out, 700c66ab6faSJens Axboe }; 7016da61809SMark Fasheh 70261e0d47cSMiklos Szeredi pipe_lock(pipe); 703c66ab6faSJens Axboe ret = __splice_from_pipe(pipe, &sd, actor); 70461e0d47cSMiklos Szeredi pipe_unlock(pipe); 7056da61809SMark Fasheh 7066da61809SMark Fasheh return ret; 7076da61809SMark Fasheh } 7086da61809SMark Fasheh 7096da61809SMark Fasheh /** 7108d020765SAl Viro * iter_file_splice_write - splice data from a pipe to a file 7118d020765SAl Viro * @pipe: pipe info 7128d020765SAl Viro * @out: file to write to 7138d020765SAl Viro * @ppos: position in @out 7148d020765SAl Viro * @len: number of bytes to splice 7158d020765SAl Viro * @flags: splice modifier flags 7168d020765SAl Viro * 7178d020765SAl Viro * Description: 7188d020765SAl Viro * Will either move or copy pages (determined by @flags options) from 7198d020765SAl Viro * the given pipe inode to the given file. 7208d020765SAl Viro * This one is ->write_iter-based. 7218d020765SAl Viro * 7228d020765SAl Viro */ 7238d020765SAl Viro ssize_t 7248d020765SAl Viro iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out, 7258d020765SAl Viro loff_t *ppos, size_t len, unsigned int flags) 7268d020765SAl Viro { 7278d020765SAl Viro struct splice_desc sd = { 7288d020765SAl Viro .total_len = len, 7298d020765SAl Viro .flags = flags, 7308d020765SAl Viro .pos = *ppos, 7318d020765SAl Viro .u.file = out, 7328d020765SAl Viro }; 7336718b6f8SDavid Howells int nbufs = pipe->max_usage; 7348d020765SAl Viro struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec), 7358d020765SAl Viro GFP_KERNEL); 7368d020765SAl Viro ssize_t ret; 7378d020765SAl Viro 7388d020765SAl Viro if (unlikely(!array)) 7398d020765SAl Viro return -ENOMEM; 7408d020765SAl Viro 7418d020765SAl Viro pipe_lock(pipe); 7428d020765SAl Viro 7438d020765SAl Viro splice_from_pipe_begin(&sd); 7448d020765SAl Viro while (sd.total_len) { 7458d020765SAl Viro struct iov_iter from; 746ec057595SLinus Torvalds unsigned int head, tail, mask; 7478d020765SAl Viro size_t left; 7488cefc107SDavid Howells int n; 7498d020765SAl Viro 7508d020765SAl Viro ret = splice_from_pipe_next(pipe, &sd); 7518d020765SAl Viro if (ret <= 0) 7528d020765SAl Viro break; 7538d020765SAl Viro 7546718b6f8SDavid Howells if (unlikely(nbufs < pipe->max_usage)) { 7558d020765SAl Viro kfree(array); 7566718b6f8SDavid Howells nbufs = pipe->max_usage; 7578d020765SAl Viro array = kcalloc(nbufs, sizeof(struct bio_vec), 7588d020765SAl Viro GFP_KERNEL); 7598d020765SAl Viro if (!array) { 7608d020765SAl Viro ret = -ENOMEM; 7618d020765SAl Viro break; 7628d020765SAl Viro } 7638d020765SAl Viro } 7648d020765SAl Viro 765ec057595SLinus Torvalds head = pipe->head; 766ec057595SLinus Torvalds tail = pipe->tail; 767ec057595SLinus Torvalds mask = pipe->ring_size - 1; 768ec057595SLinus Torvalds 7698d020765SAl Viro /* build the vector */ 7708d020765SAl Viro left = sd.total_len; 7710f1d344fSPavel Begunkov for (n = 0; !pipe_empty(head, tail) && left && n < nbufs; tail++) { 7728cefc107SDavid Howells struct pipe_buffer *buf = &pipe->bufs[tail & mask]; 7738d020765SAl Viro size_t this_len = buf->len; 7748d020765SAl Viro 7750f1d344fSPavel Begunkov /* zero-length bvecs are not supported, skip them */ 7760f1d344fSPavel Begunkov if (!this_len) 7770f1d344fSPavel Begunkov continue; 7780f1d344fSPavel Begunkov this_len = min(this_len, left); 7798d020765SAl Viro 780fba597dbSMiklos Szeredi ret = pipe_buf_confirm(pipe, buf); 7818d020765SAl Viro if (unlikely(ret)) { 7828d020765SAl Viro if (ret == -ENODATA) 7838d020765SAl Viro ret = 0; 7848d020765SAl Viro goto done; 7858d020765SAl Viro } 7868d020765SAl Viro 787664e4078SChristoph Hellwig bvec_set_page(&array[n], buf->page, this_len, 788664e4078SChristoph Hellwig buf->offset); 7898d020765SAl Viro left -= this_len; 7900f1d344fSPavel Begunkov n++; 7918d020765SAl Viro } 7928d020765SAl Viro 793de4eda9dSAl Viro iov_iter_bvec(&from, ITER_SOURCE, array, n, sd.total_len - left); 794abbb6589SChristoph Hellwig ret = vfs_iter_write(out, &from, &sd.pos, 0); 7958d020765SAl Viro if (ret <= 0) 7968d020765SAl Viro break; 7978d020765SAl Viro 7988d020765SAl Viro sd.num_spliced += ret; 7998d020765SAl Viro sd.total_len -= ret; 800dbe4e192SChristoph Hellwig *ppos = sd.pos; 8018d020765SAl Viro 8028d020765SAl Viro /* dismiss the fully eaten buffers, adjust the partial one */ 8038cefc107SDavid Howells tail = pipe->tail; 8048d020765SAl Viro while (ret) { 8058cefc107SDavid Howells struct pipe_buffer *buf = &pipe->bufs[tail & mask]; 8068d020765SAl Viro if (ret >= buf->len) { 8078d020765SAl Viro ret -= buf->len; 8088d020765SAl Viro buf->len = 0; 809a779638cSMiklos Szeredi pipe_buf_release(pipe, buf); 8108cefc107SDavid Howells tail++; 8118cefc107SDavid Howells pipe->tail = tail; 8128d020765SAl Viro if (pipe->files) 8138d020765SAl Viro sd.need_wakeup = true; 8148d020765SAl Viro } else { 8158d020765SAl Viro buf->offset += ret; 8168d020765SAl Viro buf->len -= ret; 8178d020765SAl Viro ret = 0; 8188d020765SAl Viro } 8198d020765SAl Viro } 8208d020765SAl Viro } 8218d020765SAl Viro done: 8228d020765SAl Viro kfree(array); 8238d020765SAl Viro splice_from_pipe_end(pipe, &sd); 8248d020765SAl Viro 8258d020765SAl Viro pipe_unlock(pipe); 8268d020765SAl Viro 8278d020765SAl Viro if (sd.num_spliced) 8288d020765SAl Viro ret = sd.num_spliced; 8298d020765SAl Viro 8308d020765SAl Viro return ret; 8318d020765SAl Viro } 8328d020765SAl Viro 8338d020765SAl Viro EXPORT_SYMBOL(iter_file_splice_write); 8348d020765SAl Viro 83583f9135bSJens Axboe /** 83683f9135bSJens Axboe * generic_splice_sendpage - splice data from a pipe to a socket 837932cc6d4SJens Axboe * @pipe: pipe to splice from 83883f9135bSJens Axboe * @out: socket to write to 839932cc6d4SJens Axboe * @ppos: position in @out 84083f9135bSJens Axboe * @len: number of bytes to splice 84183f9135bSJens Axboe * @flags: splice modifier flags 84283f9135bSJens Axboe * 843932cc6d4SJens Axboe * Description: 84483f9135bSJens Axboe * Will send @len bytes from the pipe to a network socket. No data copying 84583f9135bSJens Axboe * is involved. 84683f9135bSJens Axboe * 84783f9135bSJens Axboe */ 8483a326a2cSIngo Molnar ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, 849cbb7e577SJens Axboe loff_t *ppos, size_t len, unsigned int flags) 8505274f052SJens Axboe { 85100522fb4SJens Axboe return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); 8525274f052SJens Axboe } 8535274f052SJens Axboe 854059a8f37SJens Axboe EXPORT_SYMBOL(generic_splice_sendpage); 855a0f06780SJeff Garzik 85636e2c742SChristoph Hellwig static int warn_unsupported(struct file *file, const char *op) 85736e2c742SChristoph Hellwig { 85836e2c742SChristoph Hellwig pr_debug_ratelimited( 85936e2c742SChristoph Hellwig "splice %s not supported for file %pD4 (pid: %d comm: %.20s)\n", 86036e2c742SChristoph Hellwig op, file, current->pid, current->comm); 86136e2c742SChristoph Hellwig return -EINVAL; 86236e2c742SChristoph Hellwig } 86336e2c742SChristoph Hellwig 86483f9135bSJens Axboe /* 86583f9135bSJens Axboe * Attempt to initiate a splice from pipe to file. 86683f9135bSJens Axboe */ 8673a326a2cSIngo Molnar static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, 868cbb7e577SJens Axboe loff_t *ppos, size_t len, unsigned int flags) 8695274f052SJens Axboe { 87036e2c742SChristoph Hellwig if (unlikely(!out->f_op->splice_write)) 87136e2c742SChristoph Hellwig return warn_unsupported(out, "write"); 87200c285d0SChristoph Hellwig return out->f_op->splice_write(pipe, out, ppos, len, flags); 8735274f052SJens Axboe } 8745274f052SJens Axboe 87583f9135bSJens Axboe /* 87683f9135bSJens Axboe * Attempt to initiate a splice from a file to a pipe. 87783f9135bSJens Axboe */ 878cbb7e577SJens Axboe static long do_splice_to(struct file *in, loff_t *ppos, 879cbb7e577SJens Axboe struct pipe_inode_info *pipe, size_t len, 880cbb7e577SJens Axboe unsigned int flags) 8815274f052SJens Axboe { 882313d64a3SAl Viro unsigned int p_space; 8835274f052SJens Axboe int ret; 8845274f052SJens Axboe 88549570e9bSJens Axboe if (unlikely(!(in->f_mode & FMODE_READ))) 8865274f052SJens Axboe return -EBADF; 8875274f052SJens Axboe 888313d64a3SAl Viro /* Don't try to read more the pipe has space for. */ 889313d64a3SAl Viro p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail); 890313d64a3SAl Viro len = min_t(size_t, len, p_space << PAGE_SHIFT); 891313d64a3SAl Viro 892cbb7e577SJens Axboe ret = rw_verify_area(READ, in, ppos, len); 8935274f052SJens Axboe if (unlikely(ret < 0)) 8945274f052SJens Axboe return ret; 8955274f052SJens Axboe 89603cc0789SAl Viro if (unlikely(len > MAX_RW_COUNT)) 89703cc0789SAl Viro len = MAX_RW_COUNT; 89803cc0789SAl Viro 89936e2c742SChristoph Hellwig if (unlikely(!in->f_op->splice_read)) 90036e2c742SChristoph Hellwig return warn_unsupported(in, "read"); 9012bc01060SChristoph Hellwig return in->f_op->splice_read(in, ppos, pipe, len, flags); 9025274f052SJens Axboe } 9035274f052SJens Axboe 904932cc6d4SJens Axboe /** 905932cc6d4SJens Axboe * splice_direct_to_actor - splices data directly between two non-pipes 906932cc6d4SJens Axboe * @in: file to splice from 907932cc6d4SJens Axboe * @sd: actor information on where to splice to 908932cc6d4SJens Axboe * @actor: handles the data splicing 909932cc6d4SJens Axboe * 910932cc6d4SJens Axboe * Description: 911932cc6d4SJens Axboe * This is a special case helper to splice directly between two 912932cc6d4SJens Axboe * points, without requiring an explicit pipe. Internally an allocated 913932cc6d4SJens Axboe * pipe is cached in the process, and reused during the lifetime of 914932cc6d4SJens Axboe * that process. 915932cc6d4SJens Axboe * 916c66ab6faSJens Axboe */ 917c66ab6faSJens Axboe ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, 918c66ab6faSJens Axboe splice_direct_actor *actor) 919b92ce558SJens Axboe { 920b92ce558SJens Axboe struct pipe_inode_info *pipe; 921b92ce558SJens Axboe long ret, bytes; 922c66ab6faSJens Axboe size_t len; 9230ff28d9fSChristophe Leroy int i, flags, more; 924b92ce558SJens Axboe 925b92ce558SJens Axboe /* 92697ef77c5SJason A. Donenfeld * We require the input to be seekable, as we don't want to randomly 92797ef77c5SJason A. Donenfeld * drop data for eg socket -> socket splicing. Use the piped splicing 92897ef77c5SJason A. Donenfeld * for that! 929b92ce558SJens Axboe */ 93097ef77c5SJason A. Donenfeld if (unlikely(!(in->f_mode & FMODE_LSEEK))) 931b92ce558SJens Axboe return -EINVAL; 932b92ce558SJens Axboe 933b92ce558SJens Axboe /* 934b92ce558SJens Axboe * neither in nor out is a pipe, setup an internal pipe attached to 935b92ce558SJens Axboe * 'out' and transfer the wanted data from 'in' to 'out' through that 936b92ce558SJens Axboe */ 937b92ce558SJens Axboe pipe = current->splice_pipe; 93849570e9bSJens Axboe if (unlikely(!pipe)) { 9397bee130eSAl Viro pipe = alloc_pipe_info(); 940b92ce558SJens Axboe if (!pipe) 941b92ce558SJens Axboe return -ENOMEM; 942b92ce558SJens Axboe 943b92ce558SJens Axboe /* 944b92ce558SJens Axboe * We don't have an immediate reader, but we'll read the stuff 94500522fb4SJens Axboe * out of the pipe right after the splice_to_pipe(). So set 946b92ce558SJens Axboe * PIPE_READERS appropriately. 947b92ce558SJens Axboe */ 948b92ce558SJens Axboe pipe->readers = 1; 949b92ce558SJens Axboe 950b92ce558SJens Axboe current->splice_pipe = pipe; 951b92ce558SJens Axboe } 952b92ce558SJens Axboe 953b92ce558SJens Axboe /* 95473d62d83SIngo Molnar * Do the splice. 955b92ce558SJens Axboe */ 956b92ce558SJens Axboe bytes = 0; 957c66ab6faSJens Axboe len = sd->total_len; 958c66ab6faSJens Axboe flags = sd->flags; 959c66ab6faSJens Axboe 960c66ab6faSJens Axboe /* 961c66ab6faSJens Axboe * Don't block on output, we have to drain the direct pipe. 962c66ab6faSJens Axboe */ 963c66ab6faSJens Axboe sd->flags &= ~SPLICE_F_NONBLOCK; 9640ff28d9fSChristophe Leroy more = sd->flags & SPLICE_F_MORE; 965b92ce558SJens Axboe 9668cefc107SDavid Howells WARN_ON_ONCE(!pipe_empty(pipe->head, pipe->tail)); 96717614445SDarrick J. Wong 968b92ce558SJens Axboe while (len) { 96951a92c0fSJens Axboe size_t read_len; 970a82c53a0STom Zanussi loff_t pos = sd->pos, prev_pos = pos; 971b92ce558SJens Axboe 972313d64a3SAl Viro ret = do_splice_to(in, &pos, pipe, len, flags); 97351a92c0fSJens Axboe if (unlikely(ret <= 0)) 974b92ce558SJens Axboe goto out_release; 975b92ce558SJens Axboe 976b92ce558SJens Axboe read_len = ret; 977c66ab6faSJens Axboe sd->total_len = read_len; 978b92ce558SJens Axboe 979b92ce558SJens Axboe /* 9800ff28d9fSChristophe Leroy * If more data is pending, set SPLICE_F_MORE 9810ff28d9fSChristophe Leroy * If this is the last data and SPLICE_F_MORE was not set 9820ff28d9fSChristophe Leroy * initially, clears it. 9830ff28d9fSChristophe Leroy */ 9840ff28d9fSChristophe Leroy if (read_len < len) 9850ff28d9fSChristophe Leroy sd->flags |= SPLICE_F_MORE; 9860ff28d9fSChristophe Leroy else if (!more) 9870ff28d9fSChristophe Leroy sd->flags &= ~SPLICE_F_MORE; 9880ff28d9fSChristophe Leroy /* 989b92ce558SJens Axboe * NOTE: nonblocking mode only applies to the input. We 990b92ce558SJens Axboe * must not do the output in nonblocking mode as then we 991b92ce558SJens Axboe * could get stuck data in the internal pipe: 992b92ce558SJens Axboe */ 993c66ab6faSJens Axboe ret = actor(pipe, sd); 994a82c53a0STom Zanussi if (unlikely(ret <= 0)) { 995a82c53a0STom Zanussi sd->pos = prev_pos; 996b92ce558SJens Axboe goto out_release; 997a82c53a0STom Zanussi } 998b92ce558SJens Axboe 999b92ce558SJens Axboe bytes += ret; 1000b92ce558SJens Axboe len -= ret; 1001bcd4f3acSJens Axboe sd->pos = pos; 1002b92ce558SJens Axboe 1003a82c53a0STom Zanussi if (ret < read_len) { 1004a82c53a0STom Zanussi sd->pos = prev_pos + ret; 100551a92c0fSJens Axboe goto out_release; 1006b92ce558SJens Axboe } 1007a82c53a0STom Zanussi } 1008b92ce558SJens Axboe 10099e97198dSJens Axboe done: 10108cefc107SDavid Howells pipe->tail = pipe->head = 0; 10119e97198dSJens Axboe file_accessed(in); 1012b92ce558SJens Axboe return bytes; 1013b92ce558SJens Axboe 1014b92ce558SJens Axboe out_release: 1015b92ce558SJens Axboe /* 1016b92ce558SJens Axboe * If we did an incomplete transfer we must release 1017b92ce558SJens Axboe * the pipe buffers in question: 1018b92ce558SJens Axboe */ 10198cefc107SDavid Howells for (i = 0; i < pipe->ring_size; i++) { 10208cefc107SDavid Howells struct pipe_buffer *buf = &pipe->bufs[i]; 1021b92ce558SJens Axboe 1022a779638cSMiklos Szeredi if (buf->ops) 1023a779638cSMiklos Szeredi pipe_buf_release(pipe, buf); 1024b92ce558SJens Axboe } 1025b92ce558SJens Axboe 10269e97198dSJens Axboe if (!bytes) 10279e97198dSJens Axboe bytes = ret; 1028b92ce558SJens Axboe 10299e97198dSJens Axboe goto done; 1030c66ab6faSJens Axboe } 1031c66ab6faSJens Axboe EXPORT_SYMBOL(splice_direct_to_actor); 1032c66ab6faSJens Axboe 1033c66ab6faSJens Axboe static int direct_splice_actor(struct pipe_inode_info *pipe, 1034c66ab6faSJens Axboe struct splice_desc *sd) 1035c66ab6faSJens Axboe { 10366a14b90bSJens Axboe struct file *file = sd->u.file; 1037c66ab6faSJens Axboe 10387995bd28SAl Viro return do_splice_from(pipe, file, sd->opos, sd->total_len, 10392cb4b05eSChangli Gao sd->flags); 1040c66ab6faSJens Axboe } 1041c66ab6faSJens Axboe 1042932cc6d4SJens Axboe /** 1043932cc6d4SJens Axboe * do_splice_direct - splices data directly between two files 1044932cc6d4SJens Axboe * @in: file to splice from 1045932cc6d4SJens Axboe * @ppos: input file offset 1046932cc6d4SJens Axboe * @out: file to splice to 1047acdb37c3SRandy Dunlap * @opos: output file offset 1048932cc6d4SJens Axboe * @len: number of bytes to splice 1049932cc6d4SJens Axboe * @flags: splice modifier flags 1050932cc6d4SJens Axboe * 1051932cc6d4SJens Axboe * Description: 1052932cc6d4SJens Axboe * For use by do_sendfile(). splice can easily emulate sendfile, but 1053932cc6d4SJens Axboe * doing it in the application would incur an extra system call 1054932cc6d4SJens Axboe * (splice in + splice out, as compared to just sendfile()). So this helper 1055932cc6d4SJens Axboe * can splice directly through a process-private pipe. 1056932cc6d4SJens Axboe * 1057932cc6d4SJens Axboe */ 1058c66ab6faSJens Axboe long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, 10597995bd28SAl Viro loff_t *opos, size_t len, unsigned int flags) 1060c66ab6faSJens Axboe { 1061c66ab6faSJens Axboe struct splice_desc sd = { 1062c66ab6faSJens Axboe .len = len, 1063c66ab6faSJens Axboe .total_len = len, 1064c66ab6faSJens Axboe .flags = flags, 1065c66ab6faSJens Axboe .pos = *ppos, 10666a14b90bSJens Axboe .u.file = out, 10677995bd28SAl Viro .opos = opos, 1068c66ab6faSJens Axboe }; 106951a92c0fSJens Axboe long ret; 1070c66ab6faSJens Axboe 107118c67cb9SAl Viro if (unlikely(!(out->f_mode & FMODE_WRITE))) 107218c67cb9SAl Viro return -EBADF; 107318c67cb9SAl Viro 107418c67cb9SAl Viro if (unlikely(out->f_flags & O_APPEND)) 107518c67cb9SAl Viro return -EINVAL; 107618c67cb9SAl Viro 107718c67cb9SAl Viro ret = rw_verify_area(WRITE, out, opos, len); 107818c67cb9SAl Viro if (unlikely(ret < 0)) 107918c67cb9SAl Viro return ret; 108018c67cb9SAl Viro 1081c66ab6faSJens Axboe ret = splice_direct_to_actor(in, &sd, direct_splice_actor); 108251a92c0fSJens Axboe if (ret > 0) 1083a82c53a0STom Zanussi *ppos = sd.pos; 108451a92c0fSJens Axboe 1085c66ab6faSJens Axboe return ret; 1086b92ce558SJens Axboe } 10871c118596SMiklos Szeredi EXPORT_SYMBOL(do_splice_direct); 1088b92ce558SJens Axboe 10898924feffSAl Viro static int wait_for_space(struct pipe_inode_info *pipe, unsigned flags) 10908924feffSAl Viro { 109152bce911SLinus Torvalds for (;;) { 109252bce911SLinus Torvalds if (unlikely(!pipe->readers)) { 109352bce911SLinus Torvalds send_sig(SIGPIPE, current, 0); 109452bce911SLinus Torvalds return -EPIPE; 109552bce911SLinus Torvalds } 10966718b6f8SDavid Howells if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) 109752bce911SLinus Torvalds return 0; 10988924feffSAl Viro if (flags & SPLICE_F_NONBLOCK) 10998924feffSAl Viro return -EAGAIN; 11008924feffSAl Viro if (signal_pending(current)) 11018924feffSAl Viro return -ERESTARTSYS; 1102472e5b05SLinus Torvalds pipe_wait_writable(pipe); 11038924feffSAl Viro } 11048924feffSAl Viro } 11058924feffSAl Viro 11067c77f0b3SMiklos Szeredi static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, 11077c77f0b3SMiklos Szeredi struct pipe_inode_info *opipe, 11087c77f0b3SMiklos Szeredi size_t len, unsigned int flags); 1109ddac0d39SJens Axboe 1110b964bf53SAl Viro long splice_file_to_pipe(struct file *in, 1111faa97c48SAl Viro struct pipe_inode_info *opipe, 1112faa97c48SAl Viro loff_t *offset, 1113faa97c48SAl Viro size_t len, unsigned int flags) 1114faa97c48SAl Viro { 1115faa97c48SAl Viro long ret; 1116faa97c48SAl Viro 1117faa97c48SAl Viro pipe_lock(opipe); 1118faa97c48SAl Viro ret = wait_for_space(opipe, flags); 1119faa97c48SAl Viro if (!ret) 1120faa97c48SAl Viro ret = do_splice_to(in, offset, opipe, len, flags); 1121faa97c48SAl Viro pipe_unlock(opipe); 1122faa97c48SAl Viro if (ret > 0) 1123faa97c48SAl Viro wakeup_pipe_readers(opipe); 1124faa97c48SAl Viro return ret; 1125faa97c48SAl Viro } 1126faa97c48SAl Viro 1127ddac0d39SJens Axboe /* 112883f9135bSJens Axboe * Determine where to splice to/from. 112983f9135bSJens Axboe */ 1130ee6e00c8SJens Axboe long do_splice(struct file *in, loff_t *off_in, struct file *out, 1131ee6e00c8SJens Axboe loff_t *off_out, size_t len, unsigned int flags) 11325274f052SJens Axboe { 11337c77f0b3SMiklos Szeredi struct pipe_inode_info *ipipe; 11347c77f0b3SMiklos Szeredi struct pipe_inode_info *opipe; 11357995bd28SAl Viro loff_t offset; 1136a4514ebdSJens Axboe long ret; 11375274f052SJens Axboe 113890da2e3fSPavel Begunkov if (unlikely(!(in->f_mode & FMODE_READ) || 113990da2e3fSPavel Begunkov !(out->f_mode & FMODE_WRITE))) 114090da2e3fSPavel Begunkov return -EBADF; 114190da2e3fSPavel Begunkov 1142c73be61cSDavid Howells ipipe = get_pipe_info(in, true); 1143c73be61cSDavid Howells opipe = get_pipe_info(out, true); 11447c77f0b3SMiklos Szeredi 11457c77f0b3SMiklos Szeredi if (ipipe && opipe) { 11467c77f0b3SMiklos Szeredi if (off_in || off_out) 11477c77f0b3SMiklos Szeredi return -ESPIPE; 11487c77f0b3SMiklos Szeredi 11497c77f0b3SMiklos Szeredi /* Splicing to self would be fun, but... */ 11507c77f0b3SMiklos Szeredi if (ipipe == opipe) 11517c77f0b3SMiklos Szeredi return -EINVAL; 11527c77f0b3SMiklos Szeredi 1153ee5e0011SSlavomir Kaslev if ((in->f_flags | out->f_flags) & O_NONBLOCK) 1154ee5e0011SSlavomir Kaslev flags |= SPLICE_F_NONBLOCK; 1155ee5e0011SSlavomir Kaslev 11567c77f0b3SMiklos Szeredi return splice_pipe_to_pipe(ipipe, opipe, len, flags); 11577c77f0b3SMiklos Szeredi } 11587c77f0b3SMiklos Szeredi 11597c77f0b3SMiklos Szeredi if (ipipe) { 1160529565dcSIngo Molnar if (off_in) 1161529565dcSIngo Molnar return -ESPIPE; 1162b92ce558SJens Axboe if (off_out) { 116319c9a49bSChangli Gao if (!(out->f_mode & FMODE_PWRITE)) 1164b92ce558SJens Axboe return -EINVAL; 1165ee6e00c8SJens Axboe offset = *off_out; 11667995bd28SAl Viro } else { 11677995bd28SAl Viro offset = out->f_pos; 11687995bd28SAl Viro } 1169529565dcSIngo Molnar 117018c67cb9SAl Viro if (unlikely(out->f_flags & O_APPEND)) 117118c67cb9SAl Viro return -EINVAL; 117218c67cb9SAl Viro 117318c67cb9SAl Viro ret = rw_verify_area(WRITE, out, &offset, len); 117418c67cb9SAl Viro if (unlikely(ret < 0)) 117518c67cb9SAl Viro return ret; 117618c67cb9SAl Viro 1177ee5e0011SSlavomir Kaslev if (in->f_flags & O_NONBLOCK) 1178ee5e0011SSlavomir Kaslev flags |= SPLICE_F_NONBLOCK; 1179ee5e0011SSlavomir Kaslev 1180500368f7SAl Viro file_start_write(out); 11817995bd28SAl Viro ret = do_splice_from(ipipe, out, &offset, len, flags); 1182500368f7SAl Viro file_end_write(out); 1183a4514ebdSJens Axboe 1184983652c6SChung-Chiang Cheng if (ret > 0) 1185983652c6SChung-Chiang Cheng fsnotify_modify(out); 1186983652c6SChung-Chiang Cheng 11877995bd28SAl Viro if (!off_out) 11887995bd28SAl Viro out->f_pos = offset; 1189ee6e00c8SJens Axboe else 1190ee6e00c8SJens Axboe *off_out = offset; 1191a4514ebdSJens Axboe 1192a4514ebdSJens Axboe return ret; 1193529565dcSIngo Molnar } 11945274f052SJens Axboe 11957c77f0b3SMiklos Szeredi if (opipe) { 1196529565dcSIngo Molnar if (off_out) 1197529565dcSIngo Molnar return -ESPIPE; 1198b92ce558SJens Axboe if (off_in) { 119919c9a49bSChangli Gao if (!(in->f_mode & FMODE_PREAD)) 1200b92ce558SJens Axboe return -EINVAL; 1201ee6e00c8SJens Axboe offset = *off_in; 12027995bd28SAl Viro } else { 12037995bd28SAl Viro offset = in->f_pos; 12047995bd28SAl Viro } 1205529565dcSIngo Molnar 1206ee5e0011SSlavomir Kaslev if (out->f_flags & O_NONBLOCK) 1207ee5e0011SSlavomir Kaslev flags |= SPLICE_F_NONBLOCK; 1208ee5e0011SSlavomir Kaslev 1209faa97c48SAl Viro ret = splice_file_to_pipe(in, opipe, &offset, len, flags); 1210983652c6SChung-Chiang Cheng 1211983652c6SChung-Chiang Cheng if (ret > 0) 1212983652c6SChung-Chiang Cheng fsnotify_access(in); 1213983652c6SChung-Chiang Cheng 12147995bd28SAl Viro if (!off_in) 12157995bd28SAl Viro in->f_pos = offset; 1216ee6e00c8SJens Axboe else 1217ee6e00c8SJens Axboe *off_in = offset; 1218a4514ebdSJens Axboe 1219a4514ebdSJens Axboe return ret; 1220529565dcSIngo Molnar } 12215274f052SJens Axboe 12225274f052SJens Axboe return -EINVAL; 12235274f052SJens Axboe } 12245274f052SJens Axboe 1225ee6e00c8SJens Axboe static long __do_splice(struct file *in, loff_t __user *off_in, 1226ee6e00c8SJens Axboe struct file *out, loff_t __user *off_out, 1227ee6e00c8SJens Axboe size_t len, unsigned int flags) 1228ee6e00c8SJens Axboe { 1229ee6e00c8SJens Axboe struct pipe_inode_info *ipipe; 1230ee6e00c8SJens Axboe struct pipe_inode_info *opipe; 1231ee6e00c8SJens Axboe loff_t offset, *__off_in = NULL, *__off_out = NULL; 1232ee6e00c8SJens Axboe long ret; 1233ee6e00c8SJens Axboe 1234ee6e00c8SJens Axboe ipipe = get_pipe_info(in, true); 1235ee6e00c8SJens Axboe opipe = get_pipe_info(out, true); 1236ee6e00c8SJens Axboe 12370f99fc51SJens Axboe if (ipipe) { 12380f99fc51SJens Axboe if (off_in) 1239ee6e00c8SJens Axboe return -ESPIPE; 12400f99fc51SJens Axboe pipe_clear_nowait(in); 12410f99fc51SJens Axboe } 12420f99fc51SJens Axboe if (opipe) { 12430f99fc51SJens Axboe if (off_out) 1244ee6e00c8SJens Axboe return -ESPIPE; 12450f99fc51SJens Axboe pipe_clear_nowait(out); 12460f99fc51SJens Axboe } 1247ee6e00c8SJens Axboe 1248ee6e00c8SJens Axboe if (off_out) { 1249ee6e00c8SJens Axboe if (copy_from_user(&offset, off_out, sizeof(loff_t))) 1250ee6e00c8SJens Axboe return -EFAULT; 1251ee6e00c8SJens Axboe __off_out = &offset; 1252ee6e00c8SJens Axboe } 1253ee6e00c8SJens Axboe if (off_in) { 1254ee6e00c8SJens Axboe if (copy_from_user(&offset, off_in, sizeof(loff_t))) 1255ee6e00c8SJens Axboe return -EFAULT; 1256ee6e00c8SJens Axboe __off_in = &offset; 1257ee6e00c8SJens Axboe } 1258ee6e00c8SJens Axboe 1259ee6e00c8SJens Axboe ret = do_splice(in, __off_in, out, __off_out, len, flags); 1260ee6e00c8SJens Axboe if (ret < 0) 1261ee6e00c8SJens Axboe return ret; 1262ee6e00c8SJens Axboe 1263ee6e00c8SJens Axboe if (__off_out && copy_to_user(off_out, __off_out, sizeof(loff_t))) 1264ee6e00c8SJens Axboe return -EFAULT; 1265ee6e00c8SJens Axboe if (__off_in && copy_to_user(off_in, __off_in, sizeof(loff_t))) 1266ee6e00c8SJens Axboe return -EFAULT; 1267ee6e00c8SJens Axboe 1268ee6e00c8SJens Axboe return ret; 1269ee6e00c8SJens Axboe } 1270ee6e00c8SJens Axboe 127179fddc4eSAl Viro static int iter_to_pipe(struct iov_iter *from, 127279fddc4eSAl Viro struct pipe_inode_info *pipe, 127379fddc4eSAl Viro unsigned flags) 1274912d35f8SJens Axboe { 127579fddc4eSAl Viro struct pipe_buffer buf = { 127679fddc4eSAl Viro .ops = &user_page_pipe_buf_ops, 127779fddc4eSAl Viro .flags = flags 127879fddc4eSAl Viro }; 127979fddc4eSAl Viro size_t total = 0; 128079fddc4eSAl Viro int ret = 0; 128179fddc4eSAl Viro 12827d690c15SAl Viro while (iov_iter_count(from)) { 128379fddc4eSAl Viro struct page *pages[16]; 12847d690c15SAl Viro ssize_t left; 1285db85a9ebSAl Viro size_t start; 12867d690c15SAl Viro int i, n; 1287912d35f8SJens Axboe 12887d690c15SAl Viro left = iov_iter_get_pages2(from, pages, ~0UL, 16, &start); 12897d690c15SAl Viro if (left <= 0) { 12907d690c15SAl Viro ret = left; 129179fddc4eSAl Viro break; 129279fddc4eSAl Viro } 1293912d35f8SJens Axboe 12947d690c15SAl Viro n = DIV_ROUND_UP(left + start, PAGE_SIZE); 12957d690c15SAl Viro for (i = 0; i < n; i++) { 12967d690c15SAl Viro int size = min_t(int, left, PAGE_SIZE - start); 12977d690c15SAl Viro 12987d690c15SAl Viro buf.page = pages[i]; 129979fddc4eSAl Viro buf.offset = start; 130079fddc4eSAl Viro buf.len = size; 130179fddc4eSAl Viro ret = add_to_pipe(pipe, &buf); 130279fddc4eSAl Viro if (unlikely(ret < 0)) { 13037d690c15SAl Viro iov_iter_revert(from, left); 13047d690c15SAl Viro // this one got dropped by add_to_pipe() 13057d690c15SAl Viro while (++i < n) 13067d690c15SAl Viro put_page(pages[i]); 13077d690c15SAl Viro goto out; 13087d690c15SAl Viro } 130979fddc4eSAl Viro total += ret; 13107d690c15SAl Viro left -= size; 13117d690c15SAl Viro start = 0; 1312912d35f8SJens Axboe } 1313912d35f8SJens Axboe } 13147d690c15SAl Viro out: 131579fddc4eSAl Viro return total ? total : ret; 1316912d35f8SJens Axboe } 1317912d35f8SJens Axboe 13186a14b90bSJens Axboe static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, 13196a14b90bSJens Axboe struct splice_desc *sd) 13206a14b90bSJens Axboe { 13216130f531SAl Viro int n = copy_page_to_iter(buf->page, buf->offset, sd->len, sd->u.data); 13226130f531SAl Viro return n == sd->len ? n : -EFAULT; 13236a14b90bSJens Axboe } 13246a14b90bSJens Axboe 13256a14b90bSJens Axboe /* 13266a14b90bSJens Axboe * For lack of a better implementation, implement vmsplice() to userspace 13276a14b90bSJens Axboe * as a simple copy of the pipes pages to the user iov. 13286a14b90bSJens Axboe */ 132987a3002aSAl Viro static long vmsplice_to_user(struct file *file, struct iov_iter *iter, 133087a3002aSAl Viro unsigned int flags) 13316a14b90bSJens Axboe { 1332c73be61cSDavid Howells struct pipe_inode_info *pipe = get_pipe_info(file, true); 133387a3002aSAl Viro struct splice_desc sd = { 133487a3002aSAl Viro .total_len = iov_iter_count(iter), 133587a3002aSAl Viro .flags = flags, 133687a3002aSAl Viro .u.data = iter 133787a3002aSAl Viro }; 133887a3002aSAl Viro long ret = 0; 13396a14b90bSJens Axboe 13406a14b90bSJens Axboe if (!pipe) 13416a14b90bSJens Axboe return -EBADF; 13426a14b90bSJens Axboe 13430f99fc51SJens Axboe pipe_clear_nowait(file); 13440f99fc51SJens Axboe 1345345995faSAl Viro if (sd.total_len) { 13466130f531SAl Viro pipe_lock(pipe); 13476130f531SAl Viro ret = __splice_from_pipe(pipe, &sd, pipe_to_user); 134861e0d47cSMiklos Szeredi pipe_unlock(pipe); 1349345995faSAl Viro } 13506a14b90bSJens Axboe 13516a14b90bSJens Axboe return ret; 13526a14b90bSJens Axboe } 13536a14b90bSJens Axboe 1354912d35f8SJens Axboe /* 1355912d35f8SJens Axboe * vmsplice splices a user address range into a pipe. It can be thought of 1356912d35f8SJens Axboe * as splice-from-memory, where the regular splice is splice-from-file (or 1357912d35f8SJens Axboe * to file). In both cases the output is a pipe, naturally. 1358912d35f8SJens Axboe */ 135987a3002aSAl Viro static long vmsplice_to_pipe(struct file *file, struct iov_iter *iter, 136087a3002aSAl Viro unsigned int flags) 1361912d35f8SJens Axboe { 1362ddac0d39SJens Axboe struct pipe_inode_info *pipe; 136387a3002aSAl Viro long ret = 0; 136479fddc4eSAl Viro unsigned buf_flag = 0; 136579fddc4eSAl Viro 136679fddc4eSAl Viro if (flags & SPLICE_F_GIFT) 136779fddc4eSAl Viro buf_flag = PIPE_BUF_FLAG_GIFT; 1368912d35f8SJens Axboe 1369c73be61cSDavid Howells pipe = get_pipe_info(file, true); 1370ddac0d39SJens Axboe if (!pipe) 1371912d35f8SJens Axboe return -EBADF; 1372912d35f8SJens Axboe 13730f99fc51SJens Axboe pipe_clear_nowait(file); 13740f99fc51SJens Axboe 13758924feffSAl Viro pipe_lock(pipe); 13768924feffSAl Viro ret = wait_for_space(pipe, flags); 137779fddc4eSAl Viro if (!ret) 137887a3002aSAl Viro ret = iter_to_pipe(iter, pipe, buf_flag); 13798924feffSAl Viro pipe_unlock(pipe); 13808924feffSAl Viro if (ret > 0) 13818924feffSAl Viro wakeup_pipe_readers(pipe); 138235f3d14dSJens Axboe return ret; 1383912d35f8SJens Axboe } 1384912d35f8SJens Axboe 138587a3002aSAl Viro static int vmsplice_type(struct fd f, int *type) 138687a3002aSAl Viro { 138787a3002aSAl Viro if (!f.file) 138887a3002aSAl Viro return -EBADF; 138987a3002aSAl Viro if (f.file->f_mode & FMODE_WRITE) { 1390de4eda9dSAl Viro *type = ITER_SOURCE; 139187a3002aSAl Viro } else if (f.file->f_mode & FMODE_READ) { 1392de4eda9dSAl Viro *type = ITER_DEST; 139387a3002aSAl Viro } else { 139487a3002aSAl Viro fdput(f); 139587a3002aSAl Viro return -EBADF; 139687a3002aSAl Viro } 139787a3002aSAl Viro return 0; 139887a3002aSAl Viro } 139987a3002aSAl Viro 14006a14b90bSJens Axboe /* 14016a14b90bSJens Axboe * Note that vmsplice only really supports true splicing _from_ user memory 14026a14b90bSJens Axboe * to a pipe, not the other way around. Splicing from user memory is a simple 14036a14b90bSJens Axboe * operation that can be supported without any funky alignment restrictions 14046a14b90bSJens Axboe * or nasty vm tricks. We simply map in the user memory and fill them into 14056a14b90bSJens Axboe * a pipe. The reverse isn't quite as easy, though. There are two possible 14066a14b90bSJens Axboe * solutions for that: 14076a14b90bSJens Axboe * 14086a14b90bSJens Axboe * - memcpy() the data internally, at which point we might as well just 14096a14b90bSJens Axboe * do a regular read() on the buffer anyway. 14106a14b90bSJens Axboe * - Lots of nasty vm tricks, that are neither fast nor flexible (it 14116a14b90bSJens Axboe * has restriction limitations on both ends of the pipe). 14126a14b90bSJens Axboe * 14136a14b90bSJens Axboe * Currently we punt and implement it as a normal copy, see pipe_to_user(). 14146a14b90bSJens Axboe * 14156a14b90bSJens Axboe */ 141687a3002aSAl Viro SYSCALL_DEFINE4(vmsplice, int, fd, const struct iovec __user *, uiov, 141730cfe4efSDominik Brodowski unsigned long, nr_segs, unsigned int, flags) 141830cfe4efSDominik Brodowski { 141987a3002aSAl Viro struct iovec iovstack[UIO_FASTIOV]; 142087a3002aSAl Viro struct iovec *iov = iovstack; 142187a3002aSAl Viro struct iov_iter iter; 142287e5e6daSJens Axboe ssize_t error; 142387a3002aSAl Viro struct fd f; 142487a3002aSAl Viro int type; 142587a3002aSAl Viro 1426598b3cecSChristoph Hellwig if (unlikely(flags & ~SPLICE_F_ALL)) 1427598b3cecSChristoph Hellwig return -EINVAL; 1428598b3cecSChristoph Hellwig 142987a3002aSAl Viro f = fdget(fd); 143087a3002aSAl Viro error = vmsplice_type(f, &type); 143187a3002aSAl Viro if (error) 143287a3002aSAl Viro return error; 143387a3002aSAl Viro 143487a3002aSAl Viro error = import_iovec(type, uiov, nr_segs, 143587a3002aSAl Viro ARRAY_SIZE(iovstack), &iov, &iter); 1436598b3cecSChristoph Hellwig if (error < 0) 1437598b3cecSChristoph Hellwig goto out_fdput; 1438598b3cecSChristoph Hellwig 1439598b3cecSChristoph Hellwig if (!iov_iter_count(&iter)) 1440598b3cecSChristoph Hellwig error = 0; 1441de4eda9dSAl Viro else if (type == ITER_SOURCE) 1442598b3cecSChristoph Hellwig error = vmsplice_to_pipe(f.file, &iter, flags); 1443598b3cecSChristoph Hellwig else 1444598b3cecSChristoph Hellwig error = vmsplice_to_user(f.file, &iter, flags); 1445598b3cecSChristoph Hellwig 144687a3002aSAl Viro kfree(iov); 1447598b3cecSChristoph Hellwig out_fdput: 144887a3002aSAl Viro fdput(f); 144987a3002aSAl Viro return error; 145030cfe4efSDominik Brodowski } 145130cfe4efSDominik Brodowski 1452836f92adSHeiko Carstens SYSCALL_DEFINE6(splice, int, fd_in, loff_t __user *, off_in, 1453836f92adSHeiko Carstens int, fd_out, loff_t __user *, off_out, 1454836f92adSHeiko Carstens size_t, len, unsigned int, flags) 14555274f052SJens Axboe { 14562903ff01SAl Viro struct fd in, out; 14575274f052SJens Axboe long error; 14585274f052SJens Axboe 14595274f052SJens Axboe if (unlikely(!len)) 14605274f052SJens Axboe return 0; 14615274f052SJens Axboe 14623d6ea290SAl Viro if (unlikely(flags & ~SPLICE_F_ALL)) 14633d6ea290SAl Viro return -EINVAL; 14643d6ea290SAl Viro 14655274f052SJens Axboe error = -EBADF; 14662903ff01SAl Viro in = fdget(fd_in); 14672903ff01SAl Viro if (in.file) { 14682903ff01SAl Viro out = fdget(fd_out); 14692903ff01SAl Viro if (out.file) { 1470ee6e00c8SJens Axboe error = __do_splice(in.file, off_in, out.file, off_out, 1471529565dcSIngo Molnar len, flags); 14722903ff01SAl Viro fdput(out); 14735274f052SJens Axboe } 14742903ff01SAl Viro fdput(in); 14755274f052SJens Axboe } 14765274f052SJens Axboe return error; 14775274f052SJens Axboe } 147870524490SJens Axboe 147970524490SJens Axboe /* 1480aadd06e5SJens Axboe * Make sure there's data to read. Wait for input if we can, otherwise 1481aadd06e5SJens Axboe * return an appropriate error. 1482aadd06e5SJens Axboe */ 14837c77f0b3SMiklos Szeredi static int ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) 1484aadd06e5SJens Axboe { 1485aadd06e5SJens Axboe int ret; 1486aadd06e5SJens Axboe 1487aadd06e5SJens Axboe /* 14888cefc107SDavid Howells * Check the pipe occupancy without the inode lock first. This function 1489aadd06e5SJens Axboe * is speculative anyways, so missing one is ok. 1490aadd06e5SJens Axboe */ 14918cefc107SDavid Howells if (!pipe_empty(pipe->head, pipe->tail)) 1492aadd06e5SJens Axboe return 0; 1493aadd06e5SJens Axboe 1494aadd06e5SJens Axboe ret = 0; 149561e0d47cSMiklos Szeredi pipe_lock(pipe); 1496aadd06e5SJens Axboe 14978cefc107SDavid Howells while (pipe_empty(pipe->head, pipe->tail)) { 1498aadd06e5SJens Axboe if (signal_pending(current)) { 1499aadd06e5SJens Axboe ret = -ERESTARTSYS; 1500aadd06e5SJens Axboe break; 1501aadd06e5SJens Axboe } 1502aadd06e5SJens Axboe if (!pipe->writers) 1503aadd06e5SJens Axboe break; 1504aadd06e5SJens Axboe if (flags & SPLICE_F_NONBLOCK) { 1505aadd06e5SJens Axboe ret = -EAGAIN; 1506aadd06e5SJens Axboe break; 1507aadd06e5SJens Axboe } 1508472e5b05SLinus Torvalds pipe_wait_readable(pipe); 1509aadd06e5SJens Axboe } 1510aadd06e5SJens Axboe 151161e0d47cSMiklos Szeredi pipe_unlock(pipe); 1512aadd06e5SJens Axboe return ret; 1513aadd06e5SJens Axboe } 1514aadd06e5SJens Axboe 1515aadd06e5SJens Axboe /* 1516aadd06e5SJens Axboe * Make sure there's writeable room. Wait for room if we can, otherwise 1517aadd06e5SJens Axboe * return an appropriate error. 1518aadd06e5SJens Axboe */ 15197c77f0b3SMiklos Szeredi static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) 1520aadd06e5SJens Axboe { 1521aadd06e5SJens Axboe int ret; 1522aadd06e5SJens Axboe 1523aadd06e5SJens Axboe /* 15248cefc107SDavid Howells * Check pipe occupancy without the inode lock first. This function 1525aadd06e5SJens Axboe * is speculative anyways, so missing one is ok. 1526aadd06e5SJens Axboe */ 1527566d1362STetsuo Handa if (!pipe_full(pipe->head, pipe->tail, pipe->max_usage)) 1528aadd06e5SJens Axboe return 0; 1529aadd06e5SJens Axboe 1530aadd06e5SJens Axboe ret = 0; 153161e0d47cSMiklos Szeredi pipe_lock(pipe); 1532aadd06e5SJens Axboe 15336718b6f8SDavid Howells while (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) { 1534aadd06e5SJens Axboe if (!pipe->readers) { 1535aadd06e5SJens Axboe send_sig(SIGPIPE, current, 0); 1536aadd06e5SJens Axboe ret = -EPIPE; 1537aadd06e5SJens Axboe break; 1538aadd06e5SJens Axboe } 1539aadd06e5SJens Axboe if (flags & SPLICE_F_NONBLOCK) { 1540aadd06e5SJens Axboe ret = -EAGAIN; 1541aadd06e5SJens Axboe break; 1542aadd06e5SJens Axboe } 1543aadd06e5SJens Axboe if (signal_pending(current)) { 1544aadd06e5SJens Axboe ret = -ERESTARTSYS; 1545aadd06e5SJens Axboe break; 1546aadd06e5SJens Axboe } 1547472e5b05SLinus Torvalds pipe_wait_writable(pipe); 1548aadd06e5SJens Axboe } 1549aadd06e5SJens Axboe 155061e0d47cSMiklos Szeredi pipe_unlock(pipe); 1551aadd06e5SJens Axboe return ret; 1552aadd06e5SJens Axboe } 1553aadd06e5SJens Axboe 1554aadd06e5SJens Axboe /* 15557c77f0b3SMiklos Szeredi * Splice contents of ipipe to opipe. 15567c77f0b3SMiklos Szeredi */ 15577c77f0b3SMiklos Szeredi static int splice_pipe_to_pipe(struct pipe_inode_info *ipipe, 15587c77f0b3SMiklos Szeredi struct pipe_inode_info *opipe, 15597c77f0b3SMiklos Szeredi size_t len, unsigned int flags) 15607c77f0b3SMiklos Szeredi { 15617c77f0b3SMiklos Szeredi struct pipe_buffer *ibuf, *obuf; 15628cefc107SDavid Howells unsigned int i_head, o_head; 15638cefc107SDavid Howells unsigned int i_tail, o_tail; 15648cefc107SDavid Howells unsigned int i_mask, o_mask; 15658cefc107SDavid Howells int ret = 0; 15667c77f0b3SMiklos Szeredi bool input_wakeup = false; 15677c77f0b3SMiklos Szeredi 15687c77f0b3SMiklos Szeredi 15697c77f0b3SMiklos Szeredi retry: 15707c77f0b3SMiklos Szeredi ret = ipipe_prep(ipipe, flags); 15717c77f0b3SMiklos Szeredi if (ret) 15727c77f0b3SMiklos Szeredi return ret; 15737c77f0b3SMiklos Szeredi 15747c77f0b3SMiklos Szeredi ret = opipe_prep(opipe, flags); 15757c77f0b3SMiklos Szeredi if (ret) 15767c77f0b3SMiklos Szeredi return ret; 15777c77f0b3SMiklos Szeredi 15787c77f0b3SMiklos Szeredi /* 15797c77f0b3SMiklos Szeredi * Potential ABBA deadlock, work around it by ordering lock 15807c77f0b3SMiklos Szeredi * grabbing by pipe info address. Otherwise two different processes 15817c77f0b3SMiklos Szeredi * could deadlock (one doing tee from A -> B, the other from B -> A). 15827c77f0b3SMiklos Szeredi */ 15837c77f0b3SMiklos Szeredi pipe_double_lock(ipipe, opipe); 15847c77f0b3SMiklos Szeredi 15858cefc107SDavid Howells i_tail = ipipe->tail; 15868cefc107SDavid Howells i_mask = ipipe->ring_size - 1; 15878cefc107SDavid Howells o_head = opipe->head; 15888cefc107SDavid Howells o_mask = opipe->ring_size - 1; 15898cefc107SDavid Howells 15907c77f0b3SMiklos Szeredi do { 15918cefc107SDavid Howells size_t o_len; 15928cefc107SDavid Howells 15937c77f0b3SMiklos Szeredi if (!opipe->readers) { 15947c77f0b3SMiklos Szeredi send_sig(SIGPIPE, current, 0); 15957c77f0b3SMiklos Szeredi if (!ret) 15967c77f0b3SMiklos Szeredi ret = -EPIPE; 15977c77f0b3SMiklos Szeredi break; 15987c77f0b3SMiklos Szeredi } 15997c77f0b3SMiklos Szeredi 16008cefc107SDavid Howells i_head = ipipe->head; 16018cefc107SDavid Howells o_tail = opipe->tail; 16028cefc107SDavid Howells 16038cefc107SDavid Howells if (pipe_empty(i_head, i_tail) && !ipipe->writers) 16047c77f0b3SMiklos Szeredi break; 16057c77f0b3SMiklos Szeredi 16067c77f0b3SMiklos Szeredi /* 16077c77f0b3SMiklos Szeredi * Cannot make any progress, because either the input 16087c77f0b3SMiklos Szeredi * pipe is empty or the output pipe is full. 16097c77f0b3SMiklos Szeredi */ 16108cefc107SDavid Howells if (pipe_empty(i_head, i_tail) || 16116718b6f8SDavid Howells pipe_full(o_head, o_tail, opipe->max_usage)) { 16127c77f0b3SMiklos Szeredi /* Already processed some buffers, break */ 16137c77f0b3SMiklos Szeredi if (ret) 16147c77f0b3SMiklos Szeredi break; 16157c77f0b3SMiklos Szeredi 16167c77f0b3SMiklos Szeredi if (flags & SPLICE_F_NONBLOCK) { 16177c77f0b3SMiklos Szeredi ret = -EAGAIN; 16187c77f0b3SMiklos Szeredi break; 16197c77f0b3SMiklos Szeredi } 16207c77f0b3SMiklos Szeredi 16217c77f0b3SMiklos Szeredi /* 16227c77f0b3SMiklos Szeredi * We raced with another reader/writer and haven't 16237c77f0b3SMiklos Szeredi * managed to process any buffers. A zero return 16247c77f0b3SMiklos Szeredi * value means EOF, so retry instead. 16257c77f0b3SMiklos Szeredi */ 16267c77f0b3SMiklos Szeredi pipe_unlock(ipipe); 16277c77f0b3SMiklos Szeredi pipe_unlock(opipe); 16287c77f0b3SMiklos Szeredi goto retry; 16297c77f0b3SMiklos Szeredi } 16307c77f0b3SMiklos Szeredi 16318cefc107SDavid Howells ibuf = &ipipe->bufs[i_tail & i_mask]; 16328cefc107SDavid Howells obuf = &opipe->bufs[o_head & o_mask]; 16337c77f0b3SMiklos Szeredi 16347c77f0b3SMiklos Szeredi if (len >= ibuf->len) { 16357c77f0b3SMiklos Szeredi /* 16367c77f0b3SMiklos Szeredi * Simply move the whole buffer from ipipe to opipe 16377c77f0b3SMiklos Szeredi */ 16387c77f0b3SMiklos Szeredi *obuf = *ibuf; 16397c77f0b3SMiklos Szeredi ibuf->ops = NULL; 16408cefc107SDavid Howells i_tail++; 16418cefc107SDavid Howells ipipe->tail = i_tail; 16427c77f0b3SMiklos Szeredi input_wakeup = true; 16438cefc107SDavid Howells o_len = obuf->len; 16448cefc107SDavid Howells o_head++; 16458cefc107SDavid Howells opipe->head = o_head; 16467c77f0b3SMiklos Szeredi } else { 16477c77f0b3SMiklos Szeredi /* 16487c77f0b3SMiklos Szeredi * Get a reference to this pipe buffer, 16497c77f0b3SMiklos Szeredi * so we can copy the contents over. 16507c77f0b3SMiklos Szeredi */ 165115fab63eSMatthew Wilcox if (!pipe_buf_get(ipipe, ibuf)) { 165215fab63eSMatthew Wilcox if (ret == 0) 165315fab63eSMatthew Wilcox ret = -EFAULT; 165415fab63eSMatthew Wilcox break; 165515fab63eSMatthew Wilcox } 16567c77f0b3SMiklos Szeredi *obuf = *ibuf; 16577c77f0b3SMiklos Szeredi 16587c77f0b3SMiklos Szeredi /* 1659f6dd9755SChristoph Hellwig * Don't inherit the gift and merge flags, we need to 16607c77f0b3SMiklos Szeredi * prevent multiple steals of this page. 16617c77f0b3SMiklos Szeredi */ 16627c77f0b3SMiklos Szeredi obuf->flags &= ~PIPE_BUF_FLAG_GIFT; 1663f6dd9755SChristoph Hellwig obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; 1664a0ce2f0aSJann Horn 16657c77f0b3SMiklos Szeredi obuf->len = len; 16668cefc107SDavid Howells ibuf->offset += len; 16678cefc107SDavid Howells ibuf->len -= len; 16688cefc107SDavid Howells o_len = len; 16698cefc107SDavid Howells o_head++; 16708cefc107SDavid Howells opipe->head = o_head; 16717c77f0b3SMiklos Szeredi } 16728cefc107SDavid Howells ret += o_len; 16738cefc107SDavid Howells len -= o_len; 16747c77f0b3SMiklos Szeredi } while (len); 16757c77f0b3SMiklos Szeredi 16767c77f0b3SMiklos Szeredi pipe_unlock(ipipe); 16777c77f0b3SMiklos Szeredi pipe_unlock(opipe); 16787c77f0b3SMiklos Szeredi 16797c77f0b3SMiklos Szeredi /* 16807c77f0b3SMiklos Szeredi * If we put data in the output pipe, wakeup any potential readers. 16817c77f0b3SMiklos Szeredi */ 1682825cdcb1SNamhyung Kim if (ret > 0) 1683825cdcb1SNamhyung Kim wakeup_pipe_readers(opipe); 1684825cdcb1SNamhyung Kim 16857c77f0b3SMiklos Szeredi if (input_wakeup) 16867c77f0b3SMiklos Szeredi wakeup_pipe_writers(ipipe); 16877c77f0b3SMiklos Szeredi 16887c77f0b3SMiklos Szeredi return ret; 16897c77f0b3SMiklos Szeredi } 16907c77f0b3SMiklos Szeredi 16917c77f0b3SMiklos Szeredi /* 169270524490SJens Axboe * Link contents of ipipe to opipe. 169370524490SJens Axboe */ 169470524490SJens Axboe static int link_pipe(struct pipe_inode_info *ipipe, 169570524490SJens Axboe struct pipe_inode_info *opipe, 169670524490SJens Axboe size_t len, unsigned int flags) 169770524490SJens Axboe { 169870524490SJens Axboe struct pipe_buffer *ibuf, *obuf; 16998cefc107SDavid Howells unsigned int i_head, o_head; 17008cefc107SDavid Howells unsigned int i_tail, o_tail; 17018cefc107SDavid Howells unsigned int i_mask, o_mask; 17028cefc107SDavid Howells int ret = 0; 170370524490SJens Axboe 170470524490SJens Axboe /* 170570524490SJens Axboe * Potential ABBA deadlock, work around it by ordering lock 170661e0d47cSMiklos Szeredi * grabbing by pipe info address. Otherwise two different processes 170770524490SJens Axboe * could deadlock (one doing tee from A -> B, the other from B -> A). 170870524490SJens Axboe */ 170961e0d47cSMiklos Szeredi pipe_double_lock(ipipe, opipe); 171070524490SJens Axboe 17118cefc107SDavid Howells i_tail = ipipe->tail; 17128cefc107SDavid Howells i_mask = ipipe->ring_size - 1; 17138cefc107SDavid Howells o_head = opipe->head; 17148cefc107SDavid Howells o_mask = opipe->ring_size - 1; 17158cefc107SDavid Howells 1716aadd06e5SJens Axboe do { 171770524490SJens Axboe if (!opipe->readers) { 171870524490SJens Axboe send_sig(SIGPIPE, current, 0); 171970524490SJens Axboe if (!ret) 172070524490SJens Axboe ret = -EPIPE; 172170524490SJens Axboe break; 172270524490SJens Axboe } 172370524490SJens Axboe 17248cefc107SDavid Howells i_head = ipipe->head; 17258cefc107SDavid Howells o_tail = opipe->tail; 17268cefc107SDavid Howells 172770524490SJens Axboe /* 17288cefc107SDavid Howells * If we have iterated all input buffers or run out of 1729aadd06e5SJens Axboe * output room, break. 173070524490SJens Axboe */ 17318cefc107SDavid Howells if (pipe_empty(i_head, i_tail) || 17326718b6f8SDavid Howells pipe_full(o_head, o_tail, opipe->max_usage)) 1733aadd06e5SJens Axboe break; 1734aadd06e5SJens Axboe 17358cefc107SDavid Howells ibuf = &ipipe->bufs[i_tail & i_mask]; 17368cefc107SDavid Howells obuf = &opipe->bufs[o_head & o_mask]; 173770524490SJens Axboe 173870524490SJens Axboe /* 173970524490SJens Axboe * Get a reference to this pipe buffer, 174070524490SJens Axboe * so we can copy the contents over. 174170524490SJens Axboe */ 174215fab63eSMatthew Wilcox if (!pipe_buf_get(ipipe, ibuf)) { 174315fab63eSMatthew Wilcox if (ret == 0) 174415fab63eSMatthew Wilcox ret = -EFAULT; 174515fab63eSMatthew Wilcox break; 174615fab63eSMatthew Wilcox } 174770524490SJens Axboe 174870524490SJens Axboe *obuf = *ibuf; 174970524490SJens Axboe 17507afa6fd0SJens Axboe /* 1751f6dd9755SChristoph Hellwig * Don't inherit the gift and merge flag, we need to prevent 1752f6dd9755SChristoph Hellwig * multiple steals of this page. 17537afa6fd0SJens Axboe */ 17547afa6fd0SJens Axboe obuf->flags &= ~PIPE_BUF_FLAG_GIFT; 1755f6dd9755SChristoph Hellwig obuf->flags &= ~PIPE_BUF_FLAG_CAN_MERGE; 1756a0ce2f0aSJann Horn 175770524490SJens Axboe if (obuf->len > len) 175870524490SJens Axboe obuf->len = len; 175970524490SJens Axboe ret += obuf->len; 176070524490SJens Axboe len -= obuf->len; 17618cefc107SDavid Howells 17628cefc107SDavid Howells o_head++; 17638cefc107SDavid Howells opipe->head = o_head; 17648cefc107SDavid Howells i_tail++; 1765aadd06e5SJens Axboe } while (len); 176670524490SJens Axboe 176761e0d47cSMiklos Szeredi pipe_unlock(ipipe); 176861e0d47cSMiklos Szeredi pipe_unlock(opipe); 176970524490SJens Axboe 1770aadd06e5SJens Axboe /* 1771aadd06e5SJens Axboe * If we put data in the output pipe, wakeup any potential readers. 1772aadd06e5SJens Axboe */ 1773825cdcb1SNamhyung Kim if (ret > 0) 1774825cdcb1SNamhyung Kim wakeup_pipe_readers(opipe); 177570524490SJens Axboe 177670524490SJens Axboe return ret; 177770524490SJens Axboe } 177870524490SJens Axboe 177970524490SJens Axboe /* 178070524490SJens Axboe * This is a tee(1) implementation that works on pipes. It doesn't copy 178170524490SJens Axboe * any data, it simply references the 'in' pages on the 'out' pipe. 178270524490SJens Axboe * The 'flags' used are the SPLICE_F_* variants, currently the only 178370524490SJens Axboe * applicable one is SPLICE_F_NONBLOCK. 178470524490SJens Axboe */ 17859dafdfc2SPavel Begunkov long do_tee(struct file *in, struct file *out, size_t len, unsigned int flags) 178670524490SJens Axboe { 1787c73be61cSDavid Howells struct pipe_inode_info *ipipe = get_pipe_info(in, true); 1788c73be61cSDavid Howells struct pipe_inode_info *opipe = get_pipe_info(out, true); 1789aadd06e5SJens Axboe int ret = -EINVAL; 179070524490SJens Axboe 179190da2e3fSPavel Begunkov if (unlikely(!(in->f_mode & FMODE_READ) || 179290da2e3fSPavel Begunkov !(out->f_mode & FMODE_WRITE))) 179390da2e3fSPavel Begunkov return -EBADF; 179490da2e3fSPavel Begunkov 179570524490SJens Axboe /* 1796aadd06e5SJens Axboe * Duplicate the contents of ipipe to opipe without actually 1797aadd06e5SJens Axboe * copying the data. 179870524490SJens Axboe */ 1799aadd06e5SJens Axboe if (ipipe && opipe && ipipe != opipe) { 1800ee5e0011SSlavomir Kaslev if ((in->f_flags | out->f_flags) & O_NONBLOCK) 1801ee5e0011SSlavomir Kaslev flags |= SPLICE_F_NONBLOCK; 1802ee5e0011SSlavomir Kaslev 1803aadd06e5SJens Axboe /* 1804aadd06e5SJens Axboe * Keep going, unless we encounter an error. The ipipe/opipe 1805aadd06e5SJens Axboe * ordering doesn't really matter. 1806aadd06e5SJens Axboe */ 18077c77f0b3SMiklos Szeredi ret = ipipe_prep(ipipe, flags); 1808aadd06e5SJens Axboe if (!ret) { 18097c77f0b3SMiklos Szeredi ret = opipe_prep(opipe, flags); 181002cf01aeSJens Axboe if (!ret) 1811aadd06e5SJens Axboe ret = link_pipe(ipipe, opipe, len, flags); 1812aadd06e5SJens Axboe } 1813aadd06e5SJens Axboe } 181470524490SJens Axboe 1815aadd06e5SJens Axboe return ret; 181670524490SJens Axboe } 181770524490SJens Axboe 1818836f92adSHeiko Carstens SYSCALL_DEFINE4(tee, int, fdin, int, fdout, size_t, len, unsigned int, flags) 181970524490SJens Axboe { 182090da2e3fSPavel Begunkov struct fd in, out; 18212903ff01SAl Viro int error; 182270524490SJens Axboe 18233d6ea290SAl Viro if (unlikely(flags & ~SPLICE_F_ALL)) 18243d6ea290SAl Viro return -EINVAL; 18253d6ea290SAl Viro 182670524490SJens Axboe if (unlikely(!len)) 182770524490SJens Axboe return 0; 182870524490SJens Axboe 182970524490SJens Axboe error = -EBADF; 18302903ff01SAl Viro in = fdget(fdin); 18312903ff01SAl Viro if (in.file) { 183290da2e3fSPavel Begunkov out = fdget(fdout); 18332903ff01SAl Viro if (out.file) { 183490da2e3fSPavel Begunkov error = do_tee(in.file, out.file, len, flags); 18352903ff01SAl Viro fdput(out); 183670524490SJens Axboe } 18372903ff01SAl Viro fdput(in); 183870524490SJens Axboe } 183970524490SJens Axboe 184070524490SJens Axboe return error; 184170524490SJens Axboe } 1842