| 1 | /* |
| 2 | * Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp |
| 3 | * Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com) |
| 4 | * Copyright (C) 2008-2009 - Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) |
| 5 | * |
| 6 | * Re-using content from kernel/relay.c |
| 7 | * |
| 8 | * This file is released under the GPL. |
| 9 | */ |
| 10 | |
| 11 | #include <linux/errno.h> |
| 12 | #include <linux/stddef.h> |
| 13 | #include <linux/slab.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/string.h> |
| 16 | #include <linux/vmalloc.h> |
| 17 | #include <linux/mm.h> |
| 18 | #include <linux/cpu.h> |
| 19 | #include <linux/splice.h> |
| 20 | #include <linux/pipe_fs_i.h> |
| 21 | #include <linux/bitops.h> |
| 22 | |
| 23 | #include "ltt-relay.h" |
| 24 | #include "ltt-relay-lockless.h" |
| 25 | |
| 26 | loff_t ltt_relay_no_llseek(struct file *file, loff_t offset, int origin) |
| 27 | { |
| 28 | return -ESPIPE; |
| 29 | } |
| 30 | |
| 31 | static void ltt_relay_pipe_buf_release(struct pipe_inode_info *pipe, |
| 32 | struct pipe_buffer *pbuf) |
| 33 | { |
| 34 | } |
| 35 | |
| 36 | static struct pipe_buf_operations ltt_relay_pipe_buf_ops = { |
| 37 | .can_merge = 0, |
| 38 | .map = generic_pipe_buf_map, |
| 39 | .unmap = generic_pipe_buf_unmap, |
| 40 | .confirm = generic_pipe_buf_confirm, |
| 41 | .release = ltt_relay_pipe_buf_release, |
| 42 | .steal = generic_pipe_buf_steal, |
| 43 | .get = generic_pipe_buf_get, |
| 44 | }; |
| 45 | |
| 46 | static void ltt_relay_page_release(struct splice_pipe_desc *spd, unsigned int i) |
| 47 | { |
| 48 | } |
| 49 | |
| 50 | /* |
| 51 | * subbuf_splice_actor - splice up to one subbuf's worth of data |
| 52 | */ |
| 53 | static int subbuf_splice_actor(struct file *in, |
| 54 | loff_t *ppos, |
| 55 | struct pipe_inode_info *pipe, |
| 56 | size_t len, |
| 57 | unsigned int flags) |
| 58 | { |
| 59 | struct ltt_chanbuf *buf = in->private_data; |
| 60 | struct ltt_chan *chan = container_of(buf->a.chan, struct ltt_chan, a); |
| 61 | unsigned int poff, subbuf_pages, nr_pages; |
| 62 | struct page *pages[PIPE_DEF_BUFFERS]; |
| 63 | struct partial_page partial[PIPE_DEF_BUFFERS]; |
| 64 | struct splice_pipe_desc spd = { |
| 65 | .pages = pages, |
| 66 | .nr_pages = 0, |
| 67 | .partial = partial, |
| 68 | .flags = flags, |
| 69 | .ops = <t_relay_pipe_buf_ops, |
| 70 | .spd_release = ltt_relay_page_release, |
| 71 | }; |
| 72 | long consumed_old, consumed_idx, roffset; |
| 73 | unsigned long bytes_avail; |
| 74 | |
| 75 | /* |
| 76 | * Check that a GET_SUBBUF ioctl has been done before. |
| 77 | */ |
| 78 | WARN_ON(atomic_long_read(&buf->active_readers) != 1); |
| 79 | consumed_old = atomic_long_read(&buf->consumed); |
| 80 | consumed_old += *ppos; |
| 81 | consumed_idx = SUBBUF_INDEX(consumed_old, chan); |
| 82 | |
| 83 | /* |
| 84 | * Adjust read len, if longer than what is available. |
| 85 | * Max read size is 1 subbuffer due to get_subbuf/put_subbuf for |
| 86 | * protection. |
| 87 | */ |
| 88 | bytes_avail = chan->a.sb_size; |
| 89 | WARN_ON(bytes_avail > chan->a.buf_size); |
| 90 | len = min_t(size_t, len, bytes_avail); |
| 91 | subbuf_pages = bytes_avail >> PAGE_SHIFT; |
| 92 | nr_pages = min_t(unsigned int, subbuf_pages, PIPE_DEF_BUFFERS); |
| 93 | roffset = consumed_old & PAGE_MASK; |
| 94 | poff = consumed_old & ~PAGE_MASK; |
| 95 | printk_dbg(KERN_DEBUG "SPLICE actor len %zu pos %zd write_pos %ld\n", |
| 96 | len, (ssize_t)*ppos, local_read(&buf->offset)); |
| 97 | |
| 98 | for (; spd.nr_pages < nr_pages; spd.nr_pages++) { |
| 99 | unsigned int this_len; |
| 100 | struct page *page; |
| 101 | |
| 102 | if (!len) |
| 103 | break; |
| 104 | printk_dbg(KERN_DEBUG "SPLICE actor loop len %zu roffset %ld\n", |
| 105 | len, roffset); |
| 106 | |
| 107 | this_len = PAGE_SIZE - poff; |
| 108 | page = ltt_relay_read_get_page(&buf->a, roffset); |
| 109 | spd.pages[spd.nr_pages] = page; |
| 110 | spd.partial[spd.nr_pages].offset = poff; |
| 111 | spd.partial[spd.nr_pages].len = this_len; |
| 112 | |
| 113 | poff = 0; |
| 114 | roffset += PAGE_SIZE; |
| 115 | len -= this_len; |
| 116 | } |
| 117 | |
| 118 | if (!spd.nr_pages) |
| 119 | return 0; |
| 120 | |
| 121 | return splice_to_pipe(pipe, &spd); |
| 122 | } |
| 123 | |
| 124 | ssize_t ltt_relay_file_splice_read(struct file *in, loff_t *ppos, |
| 125 | struct pipe_inode_info *pipe, size_t len, |
| 126 | unsigned int flags) |
| 127 | { |
| 128 | ssize_t spliced; |
| 129 | int ret; |
| 130 | |
| 131 | ret = 0; |
| 132 | spliced = 0; |
| 133 | |
| 134 | printk_dbg(KERN_DEBUG "SPLICE read len %zu pos %zd\n", len, |
| 135 | (ssize_t)*ppos); |
| 136 | while (len && !spliced) { |
| 137 | ret = subbuf_splice_actor(in, ppos, pipe, len, flags); |
| 138 | printk_dbg(KERN_DEBUG "SPLICE read loop ret %d\n", ret); |
| 139 | if (ret < 0) |
| 140 | break; |
| 141 | else if (!ret) { |
| 142 | if (flags & SPLICE_F_NONBLOCK) |
| 143 | ret = -EAGAIN; |
| 144 | break; |
| 145 | } |
| 146 | |
| 147 | *ppos += ret; |
| 148 | if (ret > len) |
| 149 | len = 0; |
| 150 | else |
| 151 | len -= ret; |
| 152 | spliced += ret; |
| 153 | } |
| 154 | |
| 155 | if (spliced) |
| 156 | return spliced; |
| 157 | |
| 158 | return ret; |
| 159 | } |