From 35f3d14dbbc58447c61e38a162ea10add6b31dc7 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 20 May 2010 10:43:18 +0200 Subject: pipe: add support for shrinking and growing pipes This patch adds F_GETPIPE_SZ and F_SETPIPE_SZ fcntl() actions for growing and shrinking the size of a pipe and adjusts pipe.c and splice.c (and relay and network splice) usage to work with these larger (or smaller) pipes. Signed-off-by: Jens Axboe --- fs/splice.c | 151 ++++++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 105 insertions(+), 46 deletions(-) (limited to 'fs/splice.c') diff --git a/fs/splice.c b/fs/splice.c index 9313b61..ac22b00 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -193,8 +193,8 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe, break; } - if (pipe->nrbufs < PIPE_BUFFERS) { - int newbuf = (pipe->curbuf + pipe->nrbufs) & (PIPE_BUFFERS - 1); + 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]; @@ -214,7 +214,7 @@ ssize_t splice_to_pipe(struct pipe_inode_info *pipe, if (!--spd->nr_pages) break; - if (pipe->nrbufs < PIPE_BUFFERS) + if (pipe->nrbufs < pipe->buffers) continue; break; @@ -265,6 +265,36 @@ static void spd_release_page(struct splice_pipe_desc *spd, unsigned int i) page_cache_release(spd->pages[i]); } +/* + * Check if we need to grow the arrays holding pages and partial page + * descriptions. + */ +int splice_grow_spd(struct pipe_inode_info *pipe, struct splice_pipe_desc *spd) +{ + if (pipe->buffers <= PIPE_DEF_BUFFERS) + return 0; + + spd->pages = kmalloc(pipe->buffers * sizeof(struct page *), GFP_KERNEL); + spd->partial = kmalloc(pipe->buffers * sizeof(struct partial_page), GFP_KERNEL); + + if (spd->pages && spd->partial) + return 0; + + kfree(spd->pages); + kfree(spd->partial); + return -ENOMEM; +} + +void splice_shrink_spd(struct pipe_inode_info *pipe, + struct splice_pipe_desc *spd) +{ + if (pipe->buffers <= PIPE_DEF_BUFFERS) + return; + + kfree(spd->pages); + kfree(spd->partial); +} + static int __generic_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, @@ -272,8 +302,8 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, { 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 *pages[PIPE_DEF_BUFFERS]; + struct partial_page partial[PIPE_DEF_BUFFERS]; struct page *page; pgoff_t index, end_index; loff_t isize; @@ -286,15 +316,18 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, .spd_release = spd_release_page, }; + if (splice_grow_spd(pipe, &spd)) + return -ENOMEM; + index = *ppos >> PAGE_CACHE_SHIFT; loff = *ppos & ~PAGE_CACHE_MASK; req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; - nr_pages = min(req_pages, (unsigned)PIPE_BUFFERS); + nr_pages = min(req_pages, pipe->buffers); /* * Lookup the (hopefully) full range of pages we need. */ - spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, pages); + spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); index += spd.nr_pages; /* @@ -335,7 +368,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, unlock_page(page); } - pages[spd.nr_pages++] = page; + spd.pages[spd.nr_pages++] = page; index++; } @@ -356,7 +389,7 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, * 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]; + page = spd.pages[page_nr]; if (PageReadahead(page)) page_cache_async_readahead(mapping, &in->f_ra, in, @@ -393,8 +426,8 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, error = -ENOMEM; break; } - page_cache_release(pages[page_nr]); - pages[page_nr] = page; + page_cache_release(spd.pages[page_nr]); + spd.pages[page_nr] = page; } /* * page was already under io and is now done, great @@ -451,8 +484,8 @@ fill_it: len = this_len; } - partial[page_nr].offset = loff; - partial[page_nr].len = this_len; + spd.partial[page_nr].offset = loff; + spd.partial[page_nr].len = this_len; len -= this_len; loff = 0; spd.nr_pages++; @@ -464,12 +497,13 @@ fill_it: * we got, 'nr_pages' is how many pages are in the map. */ while (page_nr < nr_pages) - page_cache_release(pages[page_nr++]); + page_cache_release(spd.pages[page_nr++]); in->f_ra.prev_pos = (loff_t)index << PAGE_CACHE_SHIFT; if (spd.nr_pages) - return splice_to_pipe(pipe, &spd); + error = splice_to_pipe(pipe, &spd); + splice_shrink_spd(pipe, &spd); return error; } @@ -560,9 +594,9 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, unsigned int nr_pages; unsigned int nr_freed; size_t offset; - struct page *pages[PIPE_BUFFERS]; - struct partial_page partial[PIPE_BUFFERS]; - struct iovec vec[PIPE_BUFFERS]; + struct page *pages[PIPE_DEF_BUFFERS]; + struct partial_page partial[PIPE_DEF_BUFFERS]; + struct iovec *vec, __vec[PIPE_DEF_BUFFERS]; pgoff_t index; ssize_t res; size_t this_len; @@ -576,11 +610,22 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, .spd_release = spd_release_page, }; + if (splice_grow_spd(pipe, &spd)) + return -ENOMEM; + + res = -ENOMEM; + vec = __vec; + if (pipe->buffers > PIPE_DEF_BUFFERS) { + vec = kmalloc(pipe->buffers * sizeof(struct iovec), GFP_KERNEL); + if (!vec) + goto shrink_ret; + } + index = *ppos >> PAGE_CACHE_SHIFT; offset = *ppos & ~PAGE_CACHE_MASK; nr_pages = (len + offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; - for (i = 0; i < nr_pages && i < PIPE_BUFFERS && len; i++) { + for (i = 0; i < nr_pages && i < pipe->buffers && len; i++) { struct page *page; page = alloc_page(GFP_USER); @@ -591,7 +636,7 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); vec[i].iov_base = (void __user *) page_address(page); vec[i].iov_len = this_len; - pages[i] = page; + spd.pages[i] = page; spd.nr_pages++; len -= this_len; offset = 0; @@ -610,11 +655,11 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, nr_freed = 0; for (i = 0; i < spd.nr_pages; i++) { this_len = min_t(size_t, vec[i].iov_len, res); - partial[i].offset = 0; - partial[i].len = this_len; + spd.partial[i].offset = 0; + spd.partial[i].len = this_len; if (!this_len) { - __free_page(pages[i]); - pages[i] = NULL; + __free_page(spd.pages[i]); + spd.pages[i] = NULL; nr_freed++; } res -= this_len; @@ -625,13 +670,18 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, if (res > 0) *ppos += res; +shrink_ret: + if (vec != __vec) + kfree(vec); + splice_shrink_spd(pipe, &spd); return res; err: for (i = 0; i < spd.nr_pages; i++) - __free_page(pages[i]); + __free_page(spd.pages[i]); - return error; + res = error; + goto shrink_ret; } EXPORT_SYMBOL(default_file_splice_read); @@ -784,7 +834,7 @@ int splice_from_pipe_feed(struct pipe_inode_info *pipe, struct splice_desc *sd, if (!buf->len) { buf->ops = NULL; ops->release(pipe, buf); - pipe->curbuf = (pipe->curbuf + 1) & (PIPE_BUFFERS - 1); + pipe->curbuf = (pipe->curbuf + 1) & (pipe->buffers - 1); pipe->nrbufs--; if (pipe->inode) sd->need_wakeup = true; @@ -1211,7 +1261,7 @@ out_release: * If we did an incomplete transfer we must release * the pipe buffers in question: */ - for (i = 0; i < PIPE_BUFFERS; i++) { + for (i = 0; i < pipe->buffers; i++) { struct pipe_buffer *buf = pipe->bufs + i; if (buf->ops) { @@ -1371,7 +1421,8 @@ static long do_splice(struct file *in, loff_t __user *off_in, */ static int get_iovec_page_array(const struct iovec __user *iov, unsigned int nr_vecs, struct page **pages, - struct partial_page *partial, int aligned) + struct partial_page *partial, int aligned, + unsigned int pipe_buffers) { int buffers = 0, error = 0; @@ -1414,8 +1465,8 @@ static int get_iovec_page_array(const struct iovec __user *iov, break; npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT; - if (npages > PIPE_BUFFERS - buffers) - npages = PIPE_BUFFERS - buffers; + if (npages > pipe_buffers - buffers) + npages = pipe_buffers - buffers; error = get_user_pages_fast((unsigned long)base, npages, 0, &pages[buffers]); @@ -1450,7 +1501,7 @@ static int get_iovec_page_array(const struct iovec __user *iov, * or if we mapped the max number of pages that we have * room for. */ - if (error < npages || buffers == PIPE_BUFFERS) + if (error < npages || buffers == pipe_buffers) break; nr_vecs--; @@ -1593,8 +1644,8 @@ 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 page *pages[PIPE_DEF_BUFFERS]; + struct partial_page partial[PIPE_DEF_BUFFERS]; struct splice_pipe_desc spd = { .pages = pages, .partial = partial, @@ -1602,17 +1653,25 @@ static long vmsplice_to_pipe(struct file *file, const struct iovec __user *iov, .ops = &user_page_pipe_buf_ops, .spd_release = spd_release_page, }; + long ret; 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 (splice_grow_spd(pipe, &spd)) + return -ENOMEM; + + spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages, + spd.partial, flags & SPLICE_F_GIFT, + pipe->buffers); if (spd.nr_pages <= 0) - return spd.nr_pages; + ret = spd.nr_pages; + else + ret = splice_to_pipe(pipe, &spd); - return splice_to_pipe(pipe, &spd); + splice_shrink_spd(pipe, &spd); + return ret; } /* @@ -1738,13 +1797,13 @@ static int opipe_prep(struct pipe_inode_info *pipe, unsigned int flags) * Check ->nrbufs without the inode lock first. This function * is speculative anyways, so missing one is ok. */ - if (pipe->nrbufs < PIPE_BUFFERS) + if (pipe->nrbufs < pipe->buffers) return 0; ret = 0; pipe_lock(pipe); - while (pipe->nrbufs >= PIPE_BUFFERS) { + while (pipe->nrbufs >= pipe->buffers) { if (!pipe->readers) { send_sig(SIGPIPE, current, 0); ret = -EPIPE; @@ -1810,7 +1869,7 @@ retry: * Cannot make any progress, because either the input * pipe is empty or the output pipe is full. */ - if (!ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) { + if (!ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) { /* Already processed some buffers, break */ if (ret) break; @@ -1831,7 +1890,7 @@ retry: } ibuf = ipipe->bufs + ipipe->curbuf; - nbuf = (opipe->curbuf + opipe->nrbufs) % PIPE_BUFFERS; + nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); obuf = opipe->bufs + nbuf; if (len >= ibuf->len) { @@ -1841,7 +1900,7 @@ retry: *obuf = *ibuf; ibuf->ops = NULL; opipe->nrbufs++; - ipipe->curbuf = (ipipe->curbuf + 1) % PIPE_BUFFERS; + ipipe->curbuf = (ipipe->curbuf + 1) & (ipipe->buffers - 1); ipipe->nrbufs--; input_wakeup = true; } else { @@ -1914,11 +1973,11 @@ static int link_pipe(struct pipe_inode_info *ipipe, * If we have iterated all input buffers or ran out of * output room, break. */ - if (i >= ipipe->nrbufs || opipe->nrbufs >= PIPE_BUFFERS) + if (i >= ipipe->nrbufs || opipe->nrbufs >= opipe->buffers) break; - ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (PIPE_BUFFERS - 1)); - nbuf = (opipe->curbuf + opipe->nrbufs) & (PIPE_BUFFERS - 1); + ibuf = ipipe->bufs + ((ipipe->curbuf + i) & (ipipe->buffers-1)); + nbuf = (opipe->curbuf + opipe->nrbufs) & (opipe->buffers - 1); /* * Get a reference to this pipe buffer, -- cgit v1.1