| /* |
| * "splice": joining two ropes together by interweaving their strands. |
| * |
| * This is the "extended pipe" functionality, where a pipe is used as |
| * an arbitrary in-memory buffer. Think of a pipe as a small kernel |
| * buffer that you can use to transfer data from one end to the other. |
| * |
| * The traditional unix read/write is extended with a "splice()" operation |
| * that transfers data buffers to or from a pipe buffer. |
| * |
| * Named by Larry McVoy, original implementation from Linus, extended by |
| * Jens to support splicing to files, network, direct splicing, etc and |
| * fixing lots of bugs. |
| * |
| * Copyright (C) 2005-2006 Jens Axboe <axboe@kernel.dk> |
| * Copyright (C) 2005-2006 Linus Torvalds <torvalds@osdl.org> |
| * Copyright (C) 2006 Ingo Molnar <mingo@elte.hu> |
| * |
| */ |
| #include <linux/fs.h> |
| #include <linux/file.h> |
| #include <linux/pagemap.h> |
| #include <linux/splice.h> |
| #include <linux/mm_inline.h> |
| #include <linux/swap.h> |
| #include <linux/writeback.h> |
| #include <linux/buffer_head.h> |
| #include <linux/module.h> |
| #include <linux/syscalls.h> |
| #include <linux/uio.h> |
| #include <linux/security.h> |
| |
| /* |
| * Attempt to steal a page from a pipe buffer. This should perhaps go into |
| * a vm helper function, it's already simplified quite a bit by the |
| * addition of remove_mapping(). If success is returned, the caller may |
| * attempt to reuse this page for another destination. |
| */ |
| static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe, |
| struct pipe_buffer *buf) |
| { |
| struct page *page = buf->page; |
| struct address_space *mapping; |
| |
| lock_page(page); |
| |
| mapping = page_mapping(page); |
| if (mapping) { |
| WARN_ON(!PageUptodate(page)); |
| |
| /* |
| * At least for ext2 with nobh option, we need to wait on |
| * writeback completing on this page, since we'll remove it |
| * from the pagecache. Otherwise truncate wont wait on the |
| * page, allowing the disk blocks to be reused by someone else |
| * before we actually wrote our data to them. fs corruption |
| * ensues. |
| */ |
| wait_on_page_writeback(page); |
| |
| if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL)) |
| goto out_unlock; |
| |
| /* |
| * If we succeeded in removing the mapping, set LRU flag |
| * and return good. |
| */ |
| if (remove_mapping(mapping, page)) { |
| buf->flags |= PIPE_BUF_FLAG_LRU; |
| return 0; |
| } |
| } |
| |
| /* |
| * Raced with truncate or failed to remove page from current |
| * address space, unlock and return failure. |
| */ |
| out_unlock: |
| unlock_page(page); |
| return 1; |
| } |
| |
| static void page_cache_pipe_buf_release(struct pipe_inode_info *pipe, |
| struct pipe_buffer *buf) |
| { |
| page_cache_release(buf->page); |
| buf->flags &= ~PIPE_BUF_FLAG_LRU; |
| } |
| |
| /* |
| * Check whether the contents of buf is OK to access. Since the content |
| * is a page cache page, IO may be in flight. |
| */ |
| static int page_cache_pipe_buf_confirm(struct pipe_inode_info *pipe, |
| struct pipe_buffer *buf) |
| { |
| struct page *page = buf->page; |
| int err; |
| |
| if (!PageUptodate(page)) { |
| lock_page(page); |
| |
| /* |
| * Page got truncated/unhashed. This will cause a 0-byte |
| * splice, if this is the first page. |
| */ |
| if (!page->mapping) { |
| err = -ENODATA; |
| goto error; |
| } |
| |
| /* |
| * Uh oh, read-error from disk. |
| */ |
| if (!PageUptodate(page)) { |
| err = -EIO; |
| goto error; |
| } |
| |
| /* |
| * Page is ok afterall, we are done. |
| */ |
| unlock_page(page); |
| } |
| |
| return 0; |
| error: |
| unlock_page(page); |
| return err; |
| } |
| |
| static const struct pipe_buf_operations page_cache_pipe_buf_ops = { |
| .can_merge = 0, |
| .map = generic_pipe_buf_map, |
| .unmap = generic_pipe_buf_unmap, |
| .confirm = page_cache_pipe_buf_confirm, |
| .release = page_cache_pipe_buf_release, |
| .steal = page_cache_pipe_buf_steal, |
| .get = generic_pipe_buf_get, |
| }; |
| |
| static int user_page_pipe_buf_steal(struct pipe_inode_info *pipe, |
| struct pipe_buffer *buf) |
| { |
| if (!(buf->flags & PIPE_BUF_FLAG_GIFT)) |
| return 1; |
| |
| buf->flags |= PIPE_BUF_FLAG_LRU; |
| return generic_pipe_buf_steal(pipe, buf); |
| } |
| |
| static const struct pipe_buf_operations user_page_pipe_buf_ops = { |
| .can_merge = 0, |
| .map = generic_pipe_buf_map, |
| .unmap = generic_pipe_buf_unmap, |
| .confirm = generic_pipe_buf_confirm, |
| .release = page_cache_pipe_buf_release, |
| .steal = user_page_pipe_buf_steal, |
| .get = generic_pipe_buf_get, |
| }; |
| |
| /** |
| * splice_to_pipe - fill passed data into a pipe |
| * @pipe: pipe to fill |
| * @spd: data to fill |
| * |
| * Description: |
| * @spd contains a map of pages and len/offset tuples, along with |
| * the struct pipe_buf_operations associated with these pages. This |
| * function will link that data to the pipe. |
| * |
| */ |
| ssize_t splice_to_pipe(struct pipe_inode_info *pipe, |
| struct splice_pipe_desc *spd) |
| { |
| unsigned int spd_pages = spd->nr_pages; |
| int ret, do_wakeup, page_nr; |
| |
| ret = 0; |
| do_wakeup = 0; |
| page_nr = 0; |
| |
| if (pipe->inode) |
| mutex_lock(&pipe->inode->i_mutex); |
| |
| for (;;) { |
| if (!pipe->readers) { |
| send_sig(SIGPIPE, current, 0); |
| if (!ret) |
| ret = -EPIPE; |
| break; |
| } |
| |
| if (pipe->nrbufs < PIPE_BUFFERS) { |
| int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); |
| struct pipe_buffer *buf = pipe->bufs + newbuf; |
| |
| buf->page = spd->pages[page_nr]; |
| buf->offset = spd->partial[page_nr].offset; |
| buf->len = spd->partial[page_nr].len; |
| buf->private = spd->partial[page_nr].private; |
| buf->ops = spd->ops; |
| if (spd->flags & SPLICE_F_GIFT) |
| buf->flags |= PIPE_BUF_FLAG_GIFT; |
| |
| pipe->nrbufs++; |
| page_nr++; |
| ret += buf->len; |
| |
| if (pipe->inode) |
| do_wakeup = 1; |
| |
| if (!--spd->nr_pages) |
| break; |
| if (pipe->nrbufs < PIPE_BUFFERS) |
| continue; |
| |
| break; |
| } |
| |
| if (spd->flags & SPLICE_F_NONBLOCK) { |
| if (!ret) |
| ret = -EAGAIN; |
| break; |
| } |
| |
| if (signal_pending(current)) { |
| if (!ret) |
| ret = -ERESTARTSYS; |
| break; |
| } |
| |
| if (do_wakeup) { |
| smp_mb(); |
| if (waitqueue_active(&pipe->wait)) |
| wake_up_interruptible_sync(&pipe->wait); |
| kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
| do_wakeup = 0; |
| } |
| |
| pipe->waiting_writers++; |
| pipe_wait(pipe); |
| pipe->waiting_writers--; |
| } |
| |
| if (pipe->inode) { |
| mutex_unlock(&pipe->inode->i_mutex); |
| |
| if (do_wakeup) { |
| smp_mb(); |
| if (waitqueue_active(&pipe->wait)) |
| wake_up_interruptible(&pipe->wait); |
| kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
| } |
| } |
| |
| while (page_nr < spd_pages) |
| spd->spd_release(spd, page_nr++); |
| |
| return ret; |
| } |
| |
| static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) |
| { |
| page_cache_release(spd->pages[i]); |
| } |
| |
| static int |
| __generic_file_splice_read(struct file *in, loff_t *ppos, |
| struct pipe_inode_info *pipe, size_t len, |
| unsigned int flags) |
| { |
| struct address_space *mapping = in->f_mapping; |
| unsigned int loff, nr_pages, req_pages; |
| struct page *pages[PIPE_BUFFERS]; |
| struct partial_page partial[PIPE_BUFFERS]; |
| struct page *page; |
| pgoff_t index, end_index; |
| loff_t isize; |
| int error, page_nr; |
| struct splice_pipe_desc spd = { |
| .pages = pages, |
| .partial = partial, |
| .flags = flags, |
| .ops = &page_cache_pipe_buf_ops, |
| .spd_release = spd_release_page, |
| }; |
| |
| index = *ppos >> PAGE_CACHE_SHIFT; |
| loff = *ppos & ~PAGE_CACHE_MASK; |
| req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS); |
| |
| /* |
| * Lookup the (hopefully) full range of pages we need. |
| */ |
| spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); |
| index += spd.nr_pages; |
| |
| /* |
| * If find_get_pages_contig() returned fewer pages than we needed, |
| * readahead/allocate the rest and fill in the holes. |
| */ |
| if (spd.nr_pages < nr_pages) |
| page_cache_sync_readahead(mapping, &in->f_ra, in, |
| index, req_pages - spd.nr_pages); |
| |
| error = 0; |
| while (spd.nr_pages < nr_pages) { |
| /* |
| * Page could be there, find_get_pages_contig() breaks on |
| * the first hole. |
| */ |
| page = find_get_page(mapping, index); |
| if (!page) { |
| /* |
| * page didn't exist, allocate one. |
| */ |
| page = page_cache_alloc_cold(mapping); |
| if (!page) |
| break; |
| |
| error = add_to_page_cache_lru(page, mapping, index, |
| mapping_gfp_mask(mapping)); |
| if (unlikely(error)) { |
| page_cache_release(page); |
| if (error == -EEXIST) |
| continue; |
| break; |
| } |
| /* |
| * add_to_page_cache() locks the page, unlock it |
| * to avoid convoluting the logic below even more. |
| */ |
| unlock_page(page); |
| } |
| |
| pages[spd.nr_pages++] = page; |
| index++; |
| } |
| |
| /* |
| * Now loop over the map and see if we need to start IO on any |
| * pages, fill in the partial map, etc. |
| */ |
| index = *ppos >> PAGE_CACHE_SHIFT; |
| nr_pages = spd.nr_pages; |
| spd.nr_pages = 0; |
| for (page_nr = 0; page_nr < nr_pages; page_nr++) { |
| unsigned int this_len; |
| |
| if (!len) |
| break; |
| |
| /* |
| * this_len is the max we'll use from this page |
| */ |
| this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); |
| page = pages[page_nr]; |
| |
| if (PageReadahead(page)) |
| page_cache_async_readahead(mapping, &in->f_ra, in, |
| page, index, req_pages - page_nr); |
| |
| /* |
| * If the page isn't uptodate, we may need to start io on it |
| */ |
| if (!PageUptodate(page)) { |
| /* |
| * If in nonblock mode then dont block on waiting |
| * for an in-flight io page |
| */ |
| if (flags & SPLICE_F_NONBLOCK) { |
| if (TestSetPageLocked(page)) { |
| error = -EAGAIN; |
| break; |
| } |
| } else |
| lock_page(page); |
| |
| /* |
| * Page was truncated, or invalidated by the |
| * filesystem. Redo the find/create, but this time the |
| * page is kept locked, so there's no chance of another |
| * race with truncate/invalidate. |
| */ |
| if (!page->mapping) { |
| unlock_page(page); |
| page = find_or_create_page(mapping, index, |
| mapping_gfp_mask(mapping)); |
| |
| if (!page) { |
| error = -ENOMEM; |
| break; |
| } |
| page_cache_release(pages[page_nr]); |
| pages[page_nr] = page; |
| } |
| /* |
| * page was already under io and is now done, great |
| */ |
| if (PageUptodate(page)) { |
| unlock_page(page); |
| goto fill_it; |
| } |
| |
| /* |
| * need to read in the page |
| */ |
| error = mapping->a_ops->readpage(in, page); |
| if (unlikely(error)) { |
| /* |
| * We really should re-lookup the page here, |
| * but it complicates things a lot. Instead |
| * lets just do what we already stored, and |
| * we'll get it the next time we are called. |
| */ |
| if (error == AOP_TRUNCATED_PAGE) |
| error = 0; |
| |
| break; |
| } |
| } |
| fill_it: |
| /* |
| * i_size must be checked after PageUptodate. |
| */ |
| isize = i_size_read(mapping->host); |
| end_index = (isize - 1) >> PAGE_CACHE_SHIFT; |
| if (unlikely(!isize || index > end_index)) |
| break; |
| |
| /* |
| * if this is the last page, see if we need to shrink |
| * the length and stop |
| */ |
| if (end_index == index) { |
| unsigned int plen; |
| |
| /* |
| * max good bytes in this page |
| */ |
| plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; |
| if (plen <= loff) |
| break; |
| |
| /* |
| * force quit after adding this page |
| */ |
| this_len = min(this_len, plen - loff); |
| len = this_len; |
| } |
| |
| partial[page_nr].offset = loff; |
| partial[page_nr].len = this_len; |
| len -= this_len; |
| loff = 0; |
| spd.nr_pages++; |
| index++; |
| } |
| |
| /* |
| * Release any pages at the end, if we quit early. 'page_nr' is how far |
| * we got, 'nr_pages' is how many pages are in the map. |
| */ |
| while (page_nr < nr_pages) |
| page_cache_release(pages[page_nr++]); |
| in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; |
| |
| if (spd.nr_pages) |
| return splice_to_pipe(pipe, &spd); |
| |
| return error; |
| } |
| |
| /** |
| * generic_file_splice_read - splice data from file to a pipe |
| * @in: file to splice from |
| * @ppos: position in @in |
| * @pipe: pipe to splice to |
| * @len: number of bytes to splice |
| * @flags: splice modifier flags |
| * |
| * Description: |
| * Will read pages from given file and fill them into a pipe. Can be |
| * used as long as the address_space operations for the source implements |
| * a readpage() hook. |
| * |
| */ |
| ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, |
| struct pipe_inode_info *pipe, size_t len, |
| unsigned int flags) |
| { |
| loff_t isize, left; |
| int ret; |
| |
| isize = i_size_read(in->f_mapping->host); |
| if (unlikely(*ppos >= isize)) |
| return 0; |
| |
| left = isize - *ppos; |
| if (unlikely(left < len)) |
| len = left; |
| |
| ret = __generic_file_splice_read(in, ppos, pipe, len, flags); |
| if (ret > 0) |
| *ppos += ret; |
| |
| return ret; |
| } |
| |
| EXPORT_SYMBOL(generic_file_splice_read); |
| |
| /* |
| * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' |
| * using sendpage(). Return the number of bytes sent. |
| */ |
| static int pipe_to_sendpage(struct pipe_inode_info *pipe, |
| struct pipe_buffer *buf, struct splice_desc *sd) |
| { |
| struct file *file = sd->u.file; |
| loff_t pos = sd->pos; |
| int ret, more; |
| |
| ret = buf->ops->confirm(pipe, buf); |
| if (!ret) { |
| more = (sd->flags & SPLICE_F_MORE) || sd->len < sd->total_len; |
| |
| ret = file->f_op->sendpage(file, buf->page, buf->offset, |
| sd->len, &pos, more); |
| } |
| |
| return ret; |
| } |
| |
| /* |
| * This is a little more tricky than the file -> pipe splicing. There are |
| * basically three cases: |
| * |
| * - Destination page already exists in the address space and there |
| * are users of it. For that case we have no other option that |
| * copying the data. Tough luck. |
| * - Destination page already exists in the address space, but there |
| * are no users of it. Make sure it's uptodate, then drop it. Fall |
| * through to last case. |
| * - Destination page does not exist, we can add the pipe page to |
| * the page cache and avoid the copy. |
| * |
| * If asked to move pages to the output file (SPLICE_F_MOVE is set in |
| * sd->flags), we attempt to migrate pages from the pipe to the output |
| * file address space page cache. This is possible if no one else has |
| * the pipe page referenced outside of the pipe and page cache. If |
| * SPLICE_F_MOVE isn't set, or we cannot move the page, we simply create |
| * a new page in the output file page cache and fill/dirty that. |
| */ |
| static int pipe_to_file(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
| struct splice_desc *sd) |
| { |
| struct file *file = sd->u.file; |
| struct address_space *mapping = file->f_mapping; |
| unsigned int offset, this_len; |
| struct page *page; |
| void *fsdata; |
| int ret; |
| |
| /* |
| * make sure the data in this buffer is uptodate |
| */ |
| ret = buf->ops->confirm(pipe, buf); |
| if (unlikely(ret)) |
| return ret; |
| |
| offset = sd->pos & ~PAGE_CACHE_MASK; |
| |
| this_len = sd->len; |
| if (this_len + offset > PAGE_CACHE_SIZE) |
| this_len = PAGE_CACHE_SIZE - offset; |
| |
| ret = pagecache_write_begin(file, mapping, sd->pos, this_len, |
| AOP_FLAG_UNINTERRUPTIBLE, &page, &fsdata); |
| if (unlikely(ret)) |
| goto out; |
| |
| if (buf->page != page) { |
| /* |
| * Careful, ->map() uses KM_USER0! |
| */ |
| char *src = buf->ops->map(pipe, buf, 1); |
| char *dst = kmap_atomic(page, KM_USER1); |
| |
| memcpy(dst + offset, src + buf->offset, this_len); |
| flush_dcache_page(page); |
| kunmap_atomic(dst, KM_USER1); |
| buf->ops->unmap(pipe, buf, src); |
| } |
| ret = pagecache_write_end(file, mapping, sd->pos, this_len, this_len, |
| page, fsdata); |
| out: |
| return ret; |
| } |
| |
| /** |
| * __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, do_wakeup, err; |
| |
| ret = 0; |
| do_wakeup = 0; |
| |
| for (;;) { |
| if (pipe->nrbufs) { |
| struct pipe_buffer *buf = pipe->bufs + pipe->curbuf; |
| const struct pipe_buf_operations *ops = buf->ops; |
| |
| sd->len = buf->len; |
| if (sd->len > sd->total_len) |
| sd->len = sd->total_len; |
| |
| err = actor(pipe, buf, sd); |
| if (err <= 0) { |
| if (!ret && err != -ENODATA) |
| ret = err; |
| |
| break; |
| } |
| |
| ret += err; |
| buf->offset += err; |
| buf->len -= err; |
| |
| sd->len -= err; |
| sd->pos += err; |
| sd->total_len -= err; |
| if (sd->len) |
| continue; |
| |
| if (!buf->len) { |
| buf->ops = NULL; |
| ops->release(pipe, buf); |
| pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); |
| pipe->nrbufs--; |
| if (pipe->inode) |
| do_wakeup = 1; |
| } |
| |
| if (!sd->total_len) |
| break; |
| } |
| |
| if (pipe->nrbufs) |
| continue; |
| if (!pipe->writers) |
| break; |
| if (!pipe->waiting_writers) { |
| if (ret) |
| break; |
| } |
| |
| if (sd->flags & SPLICE_F_NONBLOCK) { |
| if (!ret) |
| ret = -EAGAIN; |
| break; |
| } |
| |
| if (signal_pending(current)) { |
| if (!ret) |
| ret = -ERESTARTSYS; |
| break; |
| } |
| |
| if (do_wakeup) { |
| smp_mb(); |
| if (waitqueue_active(&pipe->wait)) |
| wake_up_interruptible_sync(&pipe->wait); |
| kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
| do_wakeup = 0; |
| } |
| |
| pipe_wait(pipe); |
| } |
| |
| if (do_wakeup) { |
| smp_mb(); |
| if (waitqueue_active(&pipe->wait)) |
| wake_up_interruptible(&pipe->wait); |
| kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
| } |
| |
| return 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 input and output inodes, |
| * 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 inode *inode = out->f_mapping->host; |
| struct splice_desc sd = { |
| .total_len = len, |
| .flags = flags, |
| .pos = *ppos, |
| .u.file = out, |
| }; |
| |
| /* |
| * The actor worker might be calling ->prepare_write and |
| * ->commit_write. Most of the time, these expect i_mutex to |
| * be held. Since this may result in an ABBA deadlock with |
| * pipe->inode, we have to order lock acquiry here. |
| */ |
| inode_double_lock(inode, pipe->inode); |
| ret = __splice_from_pipe(pipe, &sd, actor); |
| inode_double_unlock(inode, pipe->inode); |
| |
| return ret; |
| } |
| |
| /** |
| * generic_file_splice_write_nolock - generic_file_splice_write without mutexes |
| * @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. The caller is responsible |
| * for acquiring i_mutex on both inodes. |
| * |
| */ |
| ssize_t |
| generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out, |
| loff_t *ppos, size_t len, unsigned int flags) |
| { |
| struct address_space *mapping = out->f_mapping; |
| struct inode *inode = mapping->host; |
| struct splice_desc sd = { |
| .total_len = len, |
| .flags = flags, |
| .pos = *ppos, |
| .u.file = out, |
| }; |
| ssize_t ret; |
| int err; |
| |
| err = remove_suid(out->f_path.dentry); |
| if (unlikely(err)) |
| return err; |
| |
| ret = __splice_from_pipe(pipe, &sd, pipe_to_file); |
| if (ret > 0) { |
| unsigned long nr_pages; |
| |
| *ppos += ret; |
| nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| |
| /* |
| * If file or inode is SYNC and we actually wrote some data, |
| * sync it. |
| */ |
| if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { |
| err = generic_osync_inode(inode, mapping, |
| OSYNC_METADATA|OSYNC_DATA); |
| |
| if (err) |
| ret = err; |
| } |
| balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
| } |
| |
| return ret; |
| } |
| |
| EXPORT_SYMBOL(generic_file_splice_write_nolock); |
| |
| /** |
| * generic_file_splice_write - splice data from a pipe to a file |
| * @pipe: pipe info |
| * @out: file to write to |
| * @ppos: position in @out |
| * @len: number of bytes to splice |
| * @flags: splice modifier flags |
| * |
| * Description: |
| * Will either move or copy pages (determined by @flags options) from |
| * the given pipe inode to the given file. |
| * |
| */ |
| ssize_t |
| generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out, |
| loff_t *ppos, size_t len, unsigned int flags) |
| { |
| struct address_space *mapping = out->f_mapping; |
| struct inode *inode = mapping->host; |
| struct splice_desc sd = { |
| .total_len = len, |
| .flags = flags, |
| .pos = *ppos, |
| .u.file = out, |
| }; |
| ssize_t ret; |
| |
| inode_double_lock(inode, pipe->inode); |
| ret = remove_suid(out->f_path.dentry); |
| if (likely(!ret)) |
| ret = __splice_from_pipe(pipe, &sd, pipe_to_file); |
| inode_double_unlock(inode, pipe->inode); |
| if (ret > 0) { |
| unsigned long nr_pages; |
| |
| *ppos += ret; |
| nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| |
| /* |
| * If file or inode is SYNC and we actually wrote some data, |
| * sync it. |
| */ |
| if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) { |
| int err; |
| |
| mutex_lock(&inode->i_mutex); |
| err = generic_osync_inode(inode, mapping, |
| OSYNC_METADATA|OSYNC_DATA); |
| mutex_unlock(&inode->i_mutex); |
| |
| if (err) |
| ret = err; |
| } |
| balance_dirty_pages_ratelimited_nr(mapping, nr_pages); |
| } |
| |
| return ret; |
| } |
| |
| EXPORT_SYMBOL(generic_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); |
| |
| /* |
| * Attempt to initiate a splice from pipe to file. |
| */ |
| static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, |
| loff_t *ppos, size_t len, unsigned int flags) |
| { |
| int ret; |
| |
| if (unlikely(!out->f_op || !out->f_op->splice_write)) |
| return -EINVAL; |
| |
| if (unlikely(!(out->f_mode & FMODE_WRITE))) |
| return -EBADF; |
| |
| ret = rw_verify_area(WRITE, out, ppos, len); |
| if (unlikely(ret < 0)) |
| return ret; |
| |
| return out->f_op->splice_write(pipe, out, ppos, len, flags); |
| } |
| |
| /* |
| * Attempt to initiate a splice from a file to a pipe. |
| */ |
| static long do_splice_to(struct file *in, loff_t *ppos, |
| struct pipe_inode_info *pipe, size_t len, |
| unsigned int flags) |
| { |
| int ret; |
| |
| if (unlikely(!in->f_op || !in->f_op->splice_read)) |
| return -EINVAL; |
| |
| if (unlikely(!(in->f_mode & FMODE_READ))) |
| return -EBADF; |
| |
| ret = rw_verify_area(READ, in, ppos, len); |
| if (unlikely(ret < 0)) |
| return ret; |
| |
| 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; |
| |
| /* |
| * We require the input being a regular file, as we don't want to |
| * randomly drop data for eg socket -> socket splicing. Use the |
| * piped splicing for that! |
| */ |
| i_mode = in->f_path.dentry->d_inode->i_mode; |
| if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) |
| return -EINVAL; |
| |
| /* |
| * neither in nor out is a pipe, setup an internal pipe attached to |
| * 'out' and transfer the wanted data from 'in' to 'out' through that |
| */ |
| pipe = current->splice_pipe; |
| if (unlikely(!pipe)) { |
| pipe = alloc_pipe_info(NULL); |
| if (!pipe) |
| return -ENOMEM; |
| |
| /* |
| * We don't have an immediate reader, but we'll read the stuff |
| * out of the pipe right after the splice_to_pipe(). So set |
| * PIPE_READERS appropriately. |
| */ |
| pipe->readers = 1; |
| |
| current->splice_pipe = pipe; |
| } |
| |
| /* |
| * Do the splice. |
| */ |
| ret = 0; |
| bytes = 0; |
| len = sd->total_len; |
| flags = sd->flags; |
| |
| /* |
| * Don't block on output, we have to drain the direct pipe. |
| */ |
| sd->flags &= ~SPLICE_F_NONBLOCK; |
| |
| while (len) { |
| size_t read_len; |
| loff_t pos = sd->pos, prev_pos = pos; |
| |
| ret = do_splice_to(in, &pos, pipe, len, flags); |
| if (unlikely(ret <= 0)) |
| goto out_release; |
| |
| read_len = ret; |
| sd->total_len = read_len; |
| |
| /* |
| * NOTE: nonblocking mode only applies to the input. We |
| * must not do the output in nonblocking mode as then we |
| * could get stuck data in the internal pipe: |
| */ |
| ret = actor(pipe, sd); |
| if (unlikely(ret <= 0)) { |
| sd->pos = prev_pos; |
| goto out_release; |
| } |
| |
| bytes += ret; |
| len -= ret; |
| sd->pos = pos; |
| |
| if (ret < read_len) { |
| sd->pos = prev_pos + ret; |
| goto out_release; |
| } |
| } |
| |
| done: |
| pipe->nrbufs = pipe->curbuf = 0; |
| file_accessed(in); |
| return bytes; |
| |
| out_release: |
| /* |
| * If we did an incomplete transfer we must release |
| * the pipe buffers in question: |
| */ |
| for (i = 0; i < PIPE_BUFFERS; i++) { |
| struct pipe_buffer *buf = pipe->bufs + i; |
| |
| if (buf->ops) { |
| buf->ops->release(pipe, buf); |
| buf->ops = NULL; |
| } |
| } |
| |
| if (!bytes) |
| bytes = ret; |
| |
| goto done; |
| } |
| EXPORT_SYMBOL(splice_direct_to_actor); |
| |
| static int direct_splice_actor(struct pipe_inode_info *pipe, |
| struct splice_desc *sd) |
| { |
| struct file *file = sd->u.file; |
| |
| return do_splice_from(pipe, file, &sd->pos, sd->total_len, sd->flags); |
| } |
| |
| /** |
| * do_splice_direct - splices data directly between two files |
| * @in: file to splice from |
| * @ppos: input file offset |
| * @out: file to splice to |
| * @len: number of bytes to splice |
| * @flags: splice modifier flags |
| * |
| * Description: |
| * For use by do_sendfile(). splice can easily emulate sendfile, but |
| * doing it in the application would incur an extra system call |
| * (splice in + splice out, as compared to just sendfile()). So this helper |
| * can splice directly through a process-private pipe. |
| * |
| */ |
| long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, |
| size_t len, unsigned int flags) |
| { |
| struct splice_desc sd = { |
| .len = len, |
| .total_len = len, |
| .flags = flags, |
| .pos = *ppos, |
| .u.file = out, |
| }; |
| long ret; |
| |
| ret = splice_direct_to_actor(in, &sd, direct_splice_actor); |
| if (ret > 0) |
| *ppos = sd.pos; |
| |
| return ret; |
| } |
| |
| /* |
| * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same |
| * location, so checking ->i_pipe is not enough to verify that this is a |
| * pipe. |
| */ |
| static inline struct pipe_inode_info *pipe_info(struct inode *inode) |
| { |
| if (S_ISFIFO(inode->i_mode)) |
| return inode->i_pipe; |
| |
| return NULL; |
| } |
| |
| /* |
| * Determine where to splice to/from. |
| */ |
| static long do_splice(struct file *in, loff_t __user *off_in, |
| struct file *out, loff_t __user *off_out, |
| size_t len, unsigned int flags) |
| { |
| struct pipe_inode_info *pipe; |
| loff_t offset, *off; |
| long ret; |
| |
| pipe = pipe_info(in->f_path.dentry->d_inode); |
| if (pipe) { |
| if (off_in) |
| return -ESPIPE; |
| if (off_out) { |
| if (out->f_op->llseek == no_llseek) |
| return -EINVAL; |
| if (copy_from_user(&offset, off_out, sizeof(loff_t))) |
| return -EFAULT; |
| off = &offset; |
| } else |
| off = &out->f_pos; |
| |
| ret = do_splice_from(pipe, out, off, len, flags); |
| |
| if (off_out && copy_to_user(off_out, off, sizeof(loff_t))) |
| ret = -EFAULT; |
| |
| return ret; |
| } |
| |
| pipe = pipe_info(out->f_path.dentry->d_inode); |
| if (pipe) { |
| if (off_out) |
| return -ESPIPE; |
| if (off_in) { |
| if (in->f_op->llseek == no_llseek) |
| return -EINVAL; |
| if (copy_from_user(&offset, off_in, sizeof(loff_t))) |
| return -EFAULT; |
| off = &offset; |
| } else |
| off = &in->f_pos; |
| |
| ret = do_splice_to(in, off, pipe, len, flags); |
| |
| if (off_in && copy_to_user(off_in, off, sizeof(loff_t))) |
| ret = -EFAULT; |
| |
| return ret; |
| } |
| |
| return -EINVAL; |
| } |
| |
| /* |
| * Map an iov into an array of pages and offset/length tupples. With the |
| * partial_page structure, we can map several non-contiguous ranges into |
| * our ones pages[] map instead of splitting that operation into pieces. |
| * Could easily be exported as a generic helper for other users, in which |
| * case one would probably want to add a 'max_nr_pages' parameter as well. |
| */ |
| static int get_iovec_page_array(const struct iovec __user *iov, |
| unsigned int nr_vecs, struct page **pages, |
| struct partial_page *partial, int aligned) |
| { |
| int buffers = 0, error = 0; |
| |
| while (nr_vecs) { |
| unsigned long off, npages; |
| struct iovec entry; |
| void __user *base; |
| size_t len; |
| int i; |
| |
| error = -EFAULT; |
| if (copy_from_user(&entry, iov, sizeof(entry))) |
| break; |
| |
| base = entry.iov_base; |
| len = entry.iov_len; |
| |
| /* |
| * Sanity check this iovec. 0 read succeeds. |
| */ |
| error = 0; |
| if (unlikely(!len)) |
| break; |
| error = -EFAULT; |
| if (!access_ok(VERIFY_READ, base, len)) |
| break; |
| |
| /* |
| * Get this base offset and number of pages, then map |
| * in the user pages. |
| */ |
| off = (unsigned long) base & ~PAGE_MASK; |
| |
| /* |
| * If asked for alignment, the offset must be zero and the |
| * length a multiple of the PAGE_SIZE. |
| */ |
| error = -EINVAL; |
| if (aligned && (off || len & ~PAGE_MASK)) |
| break; |
| |
| npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| if (npages > PIPE_BUFFERS - buffers) |
| npages = PIPE_BUFFERS - buffers; |
| |
| error = get_user_pages_fast((unsigned long)base, npages, |
| 0, &pages[buffers]); |
| |
| if (unlikely(error <= 0)) |
| break; |
| |
| /* |
| * Fill this contiguous range into the partial page map. |
| */ |
| for (i = 0; i < error; i++) { |
| const int plen = min_t(size_t, len, PAGE_SIZE - off); |
| |
| partial[buffers].offset = off; |
| partial[buffers].len = plen; |
| |
| off = 0; |
| len -= plen; |
| buffers++; |
| } |
| |
| /* |
| * We didn't complete this iov, stop here since it probably |
| * means we have to move some of this into a pipe to |
| * be able to continue. |
| */ |
| if (len) |
| break; |
| |
| /* |
| * Don't continue if we mapped fewer pages than we asked for, |
| * or if we mapped the max number of pages that we have |
| * room for. |
| */ |
| if (error < npages || buffers == PIPE_BUFFERS) |
| break; |
| |
| nr_vecs--; |
| iov++; |
| } |
| |
| if (buffers) |
| return buffers; |
| |
| return error; |
| } |
| |
| static int pipe_to_user(struct pipe_inode_info *pipe, struct pipe_buffer *buf, |
| struct splice_desc *sd) |
| { |
| char *src; |
| int ret; |
| |
| ret = buf->ops->confirm(pipe, buf); |
| if (unlikely(ret)) |
| return ret; |
| |
| /* |
| * See if we can use the atomic maps, by prefaulting in the |
| * pages and doing an atomic copy |
| */ |
| if (!fault_in_pages_writeable(sd->u.userptr, sd->len)) { |
| src = buf->ops->map(pipe, buf, 1); |
| ret = __copy_to_user_inatomic(sd->u.userptr, src + buf->offset, |
| sd->len); |
| buf->ops->unmap(pipe, buf, src); |
| if (!ret) { |
| ret = sd->len; |
| goto out; |
| } |
| } |
| |
| /* |
| * No dice, use slow non-atomic map and copy |
| */ |
| src = buf->ops->map(pipe, buf, 0); |
| |
| ret = sd->len; |
| if (copy_to_user(sd->u.userptr, src + buf->offset, sd->len)) |
| ret = -EFAULT; |
| |
| buf->ops->unmap(pipe, buf, src); |
| out: |
| if (ret > 0) |
| sd->u.userptr += ret; |
| return ret; |
| } |
| |
| /* |
| * For lack of a better implementation, implement vmsplice() to userspace |
| * as a simple copy of the pipes pages to the user iov. |
| */ |
| static long vmsplice_to_user(struct file *file, const struct iovec __user *iov, |
| unsigned long nr_segs, unsigned int flags) |
| { |
| struct pipe_inode_info *pipe; |
| struct splice_desc sd; |
| ssize_t size; |
| int error; |
| long ret; |
| |
| pipe = pipe_info(file->f_path.dentry->d_inode); |
| if (!pipe) |
| return -EBADF; |
| |
| if (pipe->inode) |
| mutex_lock(&pipe->inode->i_mutex); |
| |
| error = ret = 0; |
| while (nr_segs) { |
| void __user *base; |
| size_t len; |
| |
| /* |
| * Get user address base and length for this iovec. |
| */ |
| error = get_user(base, &iov->iov_base); |
| if (unlikely(error)) |
| break; |
| error = get_user(len, &iov->iov_len); |
| if (unlikely(error)) |
| break; |
| |
| /* |
| * Sanity check this iovec. 0 read succeeds. |
| */ |
| if (unlikely(!len)) |
| break; |
| if (unlikely(!base)) { |
| error = -EFAULT; |
| break; |
| } |
| |
| if (unlikely(!access_ok(VERIFY_WRITE, base, len))) { |
| error = -EFAULT; |
| break; |
| } |
| |
| sd.len = 0; |
| sd.total_len = len; |
| sd.flags = flags; |
| sd.u.userptr = base; |
| sd.pos = 0; |
| |
| size = __splice_from_pipe(pipe, &sd, pipe_to_user); |
| if (size < 0) { |
| if (!ret) |
| ret = size; |
| |
| break; |
| } |
| |
| ret += size; |
| |
| if (size < len) |
| break; |
| |
| nr_segs--; |
| iov++; |
| } |
| |
| if (pipe->inode) |
| mutex_unlock(&pipe->inode->i_mutex); |
| |
| if (!ret) |
| ret = error; |
| |
| return ret; |
| } |
| |
| /* |
| * vmsplice splices a user address range into a pipe. It can be thought of |
| * as splice-from-memory, where the regular splice is splice-from-file (or |
| * to file). In both cases the output is a pipe, naturally. |
| */ |
| static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, |
| unsigned long nr_segs, unsigned int flags) |
| { |
| struct pipe_inode_info *pipe; |
| struct page *pages[PIPE_BUFFERS]; |
| struct partial_page partial[PIPE_BUFFERS]; |
| struct splice_pipe_desc spd = { |
| .pages = pages, |
| .partial = partial, |
| .flags = flags, |
| .ops = &user_page_pipe_buf_ops, |
| .spd_release = spd_release_page, |
| }; |
| |
| pipe = pipe_info(file->f_path.dentry->d_inode); |
| if (!pipe) |
| return -EBADF; |
| |
| spd.nr_pages = get_iovec_page_array(iov, nr_segs, pages, partial, |
| flags & SPLICE_F_GIFT); |
| if (spd.nr_pages <= 0) |
| return spd.nr_pages; |
| |
| return splice_to_pipe(pipe, &spd); |
| } |
| |
| /* |
| * 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(). |
| * |
| */ |
| asmlinkage long sys_vmsplice(int fd, const struct iovec __user *iov, |
| unsigned long nr_segs, unsigned int flags) |
| { |
| struct file *file; |
| long error; |
| int fput; |
| |
| if (unlikely(nr_segs > UIO_MAXIOV)) |
| return -EINVAL; |
| else if (unlikely(!nr_segs)) |
| return 0; |
| |
| error = -EBADF; |
| file = fget_light(fd, &fput); |
| if (file) { |
| if (file->f_mode & FMODE_WRITE) |
| error = vmsplice_to_pipe(file, iov, nr_segs, flags); |
| else if (file->f_mode & FMODE_READ) |
| error = vmsplice_to_user(file, iov, nr_segs, flags); |
| |
| fput_light(file, fput); |
| } |
| |
| return error; |
| } |
| |
| asmlinkage long sys_splice(int fd_in, loff_t __user *off_in, |
| int fd_out, loff_t __user *off_out, |
| size_t len, unsigned int flags) |
| { |
| long error; |
| struct file *in, *out; |
| int fput_in, fput_out; |
| |
| if (unlikely(!len)) |
| return 0; |
| |
| error = -EBADF; |
| in = fget_light(fd_in, &fput_in); |
| if (in) { |
| if (in->f_mode & FMODE_READ) { |
| out = fget_light(fd_out, &fput_out); |
| if (out) { |
| if (out->f_mode & FMODE_WRITE) |
| error = do_splice(in, off_in, |
| out, off_out, |
| len, flags); |
| fput_light(out, fput_out); |
| } |
| } |
| |
| fput_light(in, fput_in); |
| } |
| |
| return error; |
| } |
| |
| /* |
| * Make sure there's data to read. Wait for input if we can, otherwise |
| * return an appropriate error. |
| */ |
| static int link_ipipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
| { |
| int ret; |
| |
| /* |
| * Check ->nrbufs without the inode lock first. This function |
| * is speculative anyways, so missing one is ok. |
| */ |
| if (pipe->nrbufs) |
| return 0; |
| |
| ret = 0; |
| mutex_lock(&pipe->inode->i_mutex); |
| |
| while (!pipe->nrbufs) { |
| if (signal_pending(current)) { |
| ret = -ERESTARTSYS; |
| break; |
| } |
| if (!pipe->writers) |
| break; |
| if (!pipe->waiting_writers) { |
| if (flags & SPLICE_F_NONBLOCK) { |
| ret = -EAGAIN; |
| break; |
| } |
| } |
| pipe_wait(pipe); |
| } |
| |
| mutex_unlock(&pipe->inode->i_mutex); |
| return ret; |
| } |
| |
| /* |
| * Make sure there's writeable room. Wait for room if we can, otherwise |
| * return an appropriate error. |
| */ |
| static int link_opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) |
| { |
| int ret; |
| |
| /* |
| * Check ->nrbufs without the inode lock first. This function |
| * is speculative anyways, so missing one is ok. |
| */ |
| if (pipe->nrbufs < PIPE_BUFFERS) |
| return 0; |
| |
| ret = 0; |
| mutex_lock(&pipe->inode->i_mutex); |
| |
| while (pipe->nrbufs >= PIPE_BUFFERS) { |
| if (!pipe->readers) { |
| send_sig(SIGPIPE, current, 0); |
| ret = -EPIPE; |
| break; |
| } |
| if (flags & SPLICE_F_NONBLOCK) { |
| ret = -EAGAIN; |
| break; |
| } |
| if (signal_pending(current)) { |
| ret = -ERESTARTSYS; |
| break; |
| } |
| pipe->waiting_writers++; |
| pipe_wait(pipe); |
| pipe->waiting_writers--; |
| } |
| |
| mutex_unlock(&pipe->inode->i_mutex); |
| return ret; |
| } |
| |
| /* |
| * Link contents of ipipe to opipe. |
| */ |
| static int link_pipe(struct pipe_inode_info *ipipe, |
| struct pipe_inode_info *opipe, |
| size_t len, unsigned int flags) |
| { |
| struct pipe_buffer *ibuf, *obuf; |
| int ret = 0, i = 0, nbuf; |
| |
| /* |
| * Potential ABBA deadlock, work around it by ordering lock |
| * grabbing by inode address. Otherwise two different processes |
| * could deadlock (one doing tee from A -> B, the other from B -> A). |
| */ |
| inode_double_lock(ipipe->inode, opipe->inode); |
| |
| do { |
| if (!opipe->readers) { |
| send_sig(SIGPIPE, current, 0); |
| if (!ret) |
| ret = -EPIPE; |
| break; |
| } |
| |
| /* |
| * If we have iterated all input buffers or ran out of |
| * output room, break. |
| */ |
| if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) |
| break; |
| |
| ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); |
| nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); |
| |
| /* |
| * Get a reference to this pipe buffer, |
| * so we can copy the contents over. |
| */ |
| ibuf->ops->get(ipipe, ibuf); |
| |
| obuf = opipe->bufs + nbuf; |
| *obuf = *ibuf; |
| |
| /* |
| * Don't inherit the gift flag, we need to |
| * prevent multiple steals of this page. |
| */ |
| obuf->flags &= ~PIPE_BUF_FLAG_GIFT; |
| |
| if (obuf->len > len) |
| obuf->len = len; |
| |
| opipe->nrbufs++; |
| ret += obuf->len; |
| len -= obuf->len; |
| i++; |
| } while (len); |
| |
| /* |
| * return EAGAIN if we have the potential of some data in the |
| * future, otherwise just return 0 |
| */ |
| if (!ret && ipipe->waiting_writers && (flags & SPLICE_F_NONBLOCK)) |
| ret = -EAGAIN; |
| |
| inode_double_unlock(ipipe->inode, opipe->inode); |
| |
| /* |
| * If we put data in the output pipe, wakeup any potential readers. |
| */ |
| if (ret > 0) { |
| smp_mb(); |
| if (waitqueue_active(&opipe->wait)) |
| wake_up_interruptible(&opipe->wait); |
| kill_fasync(&opipe->fasync_readers, SIGIO, POLL_IN); |
| } |
| |
| return ret; |
| } |
| |
| /* |
| * This is a tee(1) implementation that works on pipes. It doesn't copy |
| * any data, it simply references the 'in' pages on the 'out' pipe. |
| * The 'flags' used are the SPLICE_F_* variants, currently the only |
| * applicable one is SPLICE_F_NONBLOCK. |
| */ |
| static long do_tee(struct file *in, struct file *out, size_t len, |
| unsigned int flags) |
| { |
| struct pipe_inode_info *ipipe = pipe_info(in->f_path.dentry->d_inode); |
| struct pipe_inode_info *opipe = pipe_info(out->f_path.dentry->d_inode); |
| int ret = -EINVAL; |
| |
| /* |
| * Duplicate the contents of ipipe to opipe without actually |
| * copying the data. |
| */ |
| if (ipipe && opipe && ipipe != opipe) { |
| /* |
| * Keep going, unless we encounter an error. The ipipe/opipe |
| * ordering doesn't really matter. |
| */ |
| ret = link_ipipe_prep(ipipe, flags); |
| if (!ret) { |
| ret = link_opipe_prep(opipe, flags); |
| if (!ret) |
| ret = link_pipe(ipipe, opipe, len, flags); |
| } |
| } |
| |
| return ret; |
| } |
| |
| asmlinkage long sys_tee(int fdin, int fdout, size_t len, unsigned int flags) |
| { |
| struct file *in; |
| int error, fput_in; |
| |
| if (unlikely(!len)) |
| return 0; |
| |
| error = -EBADF; |
| in = fget_light(fdin, &fput_in); |
| if (in) { |
| if (in->f_mode & FMODE_READ) { |
| int fput_out; |
| struct file *out = fget_light(fdout, &fput_out); |
| |
| if (out) { |
| if (out->f_mode & FMODE_WRITE) |
| error = do_tee(in, out, len, flags); |
| fput_light(out, fput_out); |
| } |
| } |
| fput_light(in, fput_in); |
| } |
| |
| return error; |
| } |