1 /*
2 * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
4 */
5
6 #include <unistd.h>
7 #include <sched.h>
8 #include <signal.h>
9 #include <errno.h>
10 #include <sys/time.h>
11 #include <asm/unistd.h>
12 #include <aio.h>
13 #include <init.h>
14 #include <kern_util.h>
15 #include <os.h>
16
17 struct aio_thread_req {
18 enum aio_type type;
19 int io_fd;
20 unsigned long long offset;
21 char *buf;
22 int len;
23 struct aio_context *aio;
24 };
25
26 #if defined(HAVE_AIO_ABI)
27 #include <linux/aio_abi.h>
28
29 /*
30 * If we have the headers, we are going to build with AIO enabled.
31 * If we don't have aio in libc, we define the necessary stubs here.
32 */
33
34 #if !defined(HAVE_AIO_LIBC)
35
io_setup(int n,aio_context_t * ctxp)36 static long io_setup(int n, aio_context_t *ctxp)
37 {
38 return syscall(__NR_io_setup, n, ctxp);
39 }
40
io_submit(aio_context_t ctx,long nr,struct iocb ** iocbpp)41 static long io_submit(aio_context_t ctx, long nr, struct iocb **iocbpp)
42 {
43 return syscall(__NR_io_submit, ctx, nr, iocbpp);
44 }
45
io_getevents(aio_context_t ctx_id,long min_nr,long nr,struct io_event * events,struct timespec * timeout)46 static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
47 struct io_event *events, struct timespec *timeout)
48 {
49 return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
50 }
51
52 #endif
53
54 /*
55 * The AIO_MMAP cases force the mmapped page into memory here
56 * rather than in whatever place first touches the data. I used
57 * to do this by touching the page, but that's delicate because
58 * gcc is prone to optimizing that away. So, what's done here
59 * is we read from the descriptor from which the page was
60 * mapped. The caller is required to pass an offset which is
61 * inside the page that was mapped. Thus, when the read
62 * returns, we know that the page is in the page cache, and
63 * that it now backs the mmapped area.
64 */
65
do_aio(aio_context_t ctx,enum aio_type type,int fd,char * buf,int len,unsigned long long offset,struct aio_context * aio)66 static int do_aio(aio_context_t ctx, enum aio_type type, int fd, char *buf,
67 int len, unsigned long long offset, struct aio_context *aio)
68 {
69 struct iocb *iocbp = & ((struct iocb) {
70 .aio_data = (unsigned long) aio,
71 .aio_fildes = fd,
72 .aio_buf = (unsigned long) buf,
73 .aio_nbytes = len,
74 .aio_offset = offset
75 });
76 char c;
77
78 switch (type) {
79 case AIO_READ:
80 iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
81 break;
82 case AIO_WRITE:
83 iocbp->aio_lio_opcode = IOCB_CMD_PWRITE;
84 break;
85 case AIO_MMAP:
86 iocbp->aio_lio_opcode = IOCB_CMD_PREAD;
87 iocbp->aio_buf = (unsigned long) &c;
88 iocbp->aio_nbytes = sizeof(c);
89 break;
90 default:
91 printk(UM_KERN_ERR "Bogus op in do_aio - %d\n", type);
92 return -EINVAL;
93 }
94
95 return (io_submit(ctx, 1, &iocbp) > 0) ? 0 : -errno;
96 }
97
98 /* Initialized in an initcall and unchanged thereafter */
99 static aio_context_t ctx = 0;
100
aio_thread(void * arg)101 static int aio_thread(void *arg)
102 {
103 struct aio_thread_reply reply;
104 struct io_event event;
105 int err, n, reply_fd;
106
107 os_fix_helper_signals();
108 while (1) {
109 n = io_getevents(ctx, 1, 1, &event, NULL);
110 if (n < 0) {
111 if (errno == EINTR)
112 continue;
113 printk(UM_KERN_ERR "aio_thread - io_getevents failed, "
114 "errno = %d\n", errno);
115 }
116 else {
117 reply = ((struct aio_thread_reply)
118 { .data = (void *) (long) event.data,
119 .err = event.res });
120 reply_fd = ((struct aio_context *) reply.data)->reply_fd;
121 err = write(reply_fd, &reply, sizeof(reply));
122 if (err != sizeof(reply))
123 printk(UM_KERN_ERR "aio_thread - write failed, "
124 "fd = %d, err = %d\n", reply_fd, errno);
125 }
126 }
127 return 0;
128 }
129
130 #endif
131
do_not_aio(struct aio_thread_req * req)132 static int do_not_aio(struct aio_thread_req *req)
133 {
134 char c;
135 unsigned long long actual;
136 int n;
137
138 actual = lseek64(req->io_fd, req->offset, SEEK_SET);
139 if (actual != req->offset)
140 return -errno;
141
142 switch (req->type) {
143 case AIO_READ:
144 n = read(req->io_fd, req->buf, req->len);
145 break;
146 case AIO_WRITE:
147 n = write(req->io_fd, req->buf, req->len);
148 break;
149 case AIO_MMAP:
150 n = read(req->io_fd, &c, sizeof(c));
151 break;
152 default:
153 printk(UM_KERN_ERR "do_not_aio - bad request type : %d\n",
154 req->type);
155 return -EINVAL;
156 }
157
158 if (n < 0)
159 return -errno;
160 return 0;
161 }
162
163 /* These are initialized in initcalls and not changed */
164 static int aio_req_fd_r = -1;
165 static int aio_req_fd_w = -1;
166 static int aio_pid = -1;
167 static unsigned long aio_stack;
168
not_aio_thread(void * arg)169 static int not_aio_thread(void *arg)
170 {
171 struct aio_thread_req req;
172 struct aio_thread_reply reply;
173 int err;
174
175 os_fix_helper_signals();
176 while (1) {
177 err = read(aio_req_fd_r, &req, sizeof(req));
178 if (err != sizeof(req)) {
179 if (err < 0)
180 printk(UM_KERN_ERR "not_aio_thread - "
181 "read failed, fd = %d, err = %d\n",
182 aio_req_fd_r,
183 errno);
184 else {
185 printk(UM_KERN_ERR "not_aio_thread - short "
186 "read, fd = %d, length = %d\n",
187 aio_req_fd_r, err);
188 }
189 continue;
190 }
191 err = do_not_aio(&req);
192 reply = ((struct aio_thread_reply) { .data = req.aio,
193 .err = err });
194 err = write(req.aio->reply_fd, &reply, sizeof(reply));
195 if (err != sizeof(reply))
196 printk(UM_KERN_ERR "not_aio_thread - write failed, "
197 "fd = %d, err = %d\n", req.aio->reply_fd, errno);
198 }
199
200 return 0;
201 }
202
init_aio_24(void)203 static int init_aio_24(void)
204 {
205 int fds[2], err;
206
207 err = os_pipe(fds, 1, 1);
208 if (err)
209 goto out;
210
211 aio_req_fd_w = fds[0];
212 aio_req_fd_r = fds[1];
213
214 err = os_set_fd_block(aio_req_fd_w, 0);
215 if (err)
216 goto out_close_pipe;
217
218 err = run_helper_thread(not_aio_thread, NULL,
219 CLONE_FILES | CLONE_VM, &aio_stack);
220 if (err < 0)
221 goto out_close_pipe;
222
223 aio_pid = err;
224 goto out;
225
226 out_close_pipe:
227 close(fds[0]);
228 close(fds[1]);
229 aio_req_fd_w = -1;
230 aio_req_fd_r = -1;
231 out:
232 #ifndef HAVE_AIO_ABI
233 printk(UM_KERN_INFO "/usr/include/linux/aio_abi.h not present during "
234 "build\n");
235 #endif
236 printk(UM_KERN_INFO "2.6 host AIO support not used - falling back to "
237 "I/O thread\n");
238 return 0;
239 }
240
241 #ifdef HAVE_AIO_ABI
242 #define DEFAULT_24_AIO 0
init_aio_26(void)243 static int init_aio_26(void)
244 {
245 int err;
246
247 if (io_setup(256, &ctx)) {
248 err = -errno;
249 printk(UM_KERN_ERR "aio_thread failed to initialize context, "
250 "err = %d\n", errno);
251 return err;
252 }
253
254 err = run_helper_thread(aio_thread, NULL,
255 CLONE_FILES | CLONE_VM, &aio_stack);
256 if (err < 0)
257 return err;
258
259 aio_pid = err;
260
261 printk(UM_KERN_INFO "Using 2.6 host AIO\n");
262 return 0;
263 }
264
submit_aio_26(enum aio_type type,int io_fd,char * buf,int len,unsigned long long offset,struct aio_context * aio)265 static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
266 unsigned long long offset, struct aio_context *aio)
267 {
268 struct aio_thread_reply reply;
269 int err;
270
271 err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
272 if (err) {
273 reply = ((struct aio_thread_reply) { .data = aio,
274 .err = err });
275 err = write(aio->reply_fd, &reply, sizeof(reply));
276 if (err != sizeof(reply)) {
277 err = -errno;
278 printk(UM_KERN_ERR "submit_aio_26 - write failed, "
279 "fd = %d, err = %d\n", aio->reply_fd, -err);
280 }
281 else err = 0;
282 }
283
284 return err;
285 }
286
287 #else
288 #define DEFAULT_24_AIO 1
init_aio_26(void)289 static int init_aio_26(void)
290 {
291 return -ENOSYS;
292 }
293
submit_aio_26(enum aio_type type,int io_fd,char * buf,int len,unsigned long long offset,struct aio_context * aio)294 static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
295 unsigned long long offset, struct aio_context *aio)
296 {
297 return -ENOSYS;
298 }
299 #endif
300
301 /* Initialized in an initcall and unchanged thereafter */
302 static int aio_24 = DEFAULT_24_AIO;
303
set_aio_24(char * name,int * add)304 static int __init set_aio_24(char *name, int *add)
305 {
306 aio_24 = 1;
307 return 0;
308 }
309
310 __uml_setup("aio=2.4", set_aio_24,
311 "aio=2.4\n"
312 " This is used to force UML to use 2.4-style AIO even when 2.6 AIO is\n"
313 " available. 2.4 AIO is a single thread that handles one request at a\n"
314 " time, synchronously. 2.6 AIO is a thread which uses the 2.6 AIO \n"
315 " interface to handle an arbitrary number of pending requests. 2.6 AIO \n"
316 " is not available in tt mode, on 2.4 hosts, or when UML is built with\n"
317 " /usr/include/linux/aio_abi.h not available. Many distributions don't\n"
318 " include aio_abi.h, so you will need to copy it from a kernel tree to\n"
319 " your /usr/include/linux in order to build an AIO-capable UML\n\n"
320 );
321
init_aio(void)322 static int init_aio(void)
323 {
324 int err;
325
326 if (!aio_24) {
327 err = init_aio_26();
328 if (err && (errno == ENOSYS)) {
329 printk(UM_KERN_INFO "2.6 AIO not supported on the "
330 "host - reverting to 2.4 AIO\n");
331 aio_24 = 1;
332 }
333 else return err;
334 }
335
336 if (aio_24)
337 return init_aio_24();
338
339 return 0;
340 }
341
342 /*
343 * The reason for the __initcall/__uml_exitcall asymmetry is that init_aio
344 * needs to be called when the kernel is running because it calls run_helper,
345 * which needs get_free_page. exit_aio is a __uml_exitcall because the generic
346 * kernel does not run __exitcalls on shutdown, and can't because many of them
347 * break when called outside of module unloading.
348 */
349 __initcall(init_aio);
350
exit_aio(void)351 static void exit_aio(void)
352 {
353 if (aio_pid != -1) {
354 os_kill_process(aio_pid, 1);
355 free_stack(aio_stack, 0);
356 }
357 }
358
359 __uml_exitcall(exit_aio);
360
submit_aio_24(enum aio_type type,int io_fd,char * buf,int len,unsigned long long offset,struct aio_context * aio)361 static int submit_aio_24(enum aio_type type, int io_fd, char *buf, int len,
362 unsigned long long offset, struct aio_context *aio)
363 {
364 struct aio_thread_req req = { .type = type,
365 .io_fd = io_fd,
366 .offset = offset,
367 .buf = buf,
368 .len = len,
369 .aio = aio,
370 };
371 int err;
372
373 err = write(aio_req_fd_w, &req, sizeof(req));
374 if (err == sizeof(req))
375 err = 0;
376 else err = -errno;
377
378 return err;
379 }
380
submit_aio(enum aio_type type,int io_fd,char * buf,int len,unsigned long long offset,int reply_fd,struct aio_context * aio)381 int submit_aio(enum aio_type type, int io_fd, char *buf, int len,
382 unsigned long long offset, int reply_fd,
383 struct aio_context *aio)
384 {
385 aio->reply_fd = reply_fd;
386 if (aio_24)
387 return submit_aio_24(type, io_fd, buf, len, offset, aio);
388 else
389 return submit_aio_26(type, io_fd, buf, len, offset, aio);
390 }
391