Remove obsolete #include <linux/config.h>
[linux-3.10.git] / block / blktrace.c
1 /*
2  * Copyright (C) 2006 Jens Axboe <axboe@suse.de>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public License
14  * along with this program; if not, write to the Free Software
15  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
16  *
17  */
18 #include <linux/kernel.h>
19 #include <linux/blkdev.h>
20 #include <linux/blktrace_api.h>
21 #include <linux/percpu.h>
22 #include <linux/init.h>
23 #include <linux/mutex.h>
24 #include <linux/debugfs.h>
25 #include <asm/uaccess.h>
26
27 static DEFINE_PER_CPU(unsigned long long, blk_trace_cpu_offset) = { 0, };
28 static unsigned int blktrace_seq __read_mostly = 1;
29
30 /*
31  * Send out a notify for this process, if we haven't done so since a trace
32  * started
33  */
34 static void trace_note_tsk(struct blk_trace *bt, struct task_struct *tsk)
35 {
36         struct blk_io_trace *t;
37
38         t = relay_reserve(bt->rchan, sizeof(*t) + sizeof(tsk->comm));
39         if (t) {
40                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
41                 t->device = bt->dev;
42                 t->action = BLK_TC_ACT(BLK_TC_NOTIFY);
43                 t->pid = tsk->pid;
44                 t->cpu = smp_processor_id();
45                 t->pdu_len = sizeof(tsk->comm);
46                 memcpy((void *) t + sizeof(*t), tsk->comm, t->pdu_len);
47                 tsk->btrace_seq = blktrace_seq;
48         }
49 }
50
51 static int act_log_check(struct blk_trace *bt, u32 what, sector_t sector,
52                          pid_t pid)
53 {
54         if (((bt->act_mask << BLK_TC_SHIFT) & what) == 0)
55                 return 1;
56         if (sector < bt->start_lba || sector > bt->end_lba)
57                 return 1;
58         if (bt->pid && pid != bt->pid)
59                 return 1;
60
61         return 0;
62 }
63
64 /*
65  * Data direction bit lookup
66  */
67 static u32 ddir_act[2] __read_mostly = { BLK_TC_ACT(BLK_TC_READ), BLK_TC_ACT(BLK_TC_WRITE) };
68
69 /*
70  * Bio action bits of interest
71  */
72 static u32 bio_act[3] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC) };
73
74 /*
75  * More could be added as needed, taking care to increment the decrementer
76  * to get correct indexing
77  */
78 #define trace_barrier_bit(rw)   \
79         (((rw) & (1 << BIO_RW_BARRIER)) >> (BIO_RW_BARRIER - 0))
80 #define trace_sync_bit(rw)      \
81         (((rw) & (1 << BIO_RW_SYNC)) >> (BIO_RW_SYNC - 1))
82
83 /*
84  * The worker for the various blk_add_trace*() types. Fills out a
85  * blk_io_trace structure and places it in a per-cpu subbuffer.
86  */
87 void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
88                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
89 {
90         struct task_struct *tsk = current;
91         struct blk_io_trace *t;
92         unsigned long flags;
93         unsigned long *sequence;
94         pid_t pid;
95         int cpu;
96
97         if (unlikely(bt->trace_state != Blktrace_running))
98                 return;
99
100         what |= ddir_act[rw & WRITE];
101         what |= bio_act[trace_barrier_bit(rw)];
102         what |= bio_act[trace_sync_bit(rw)];
103
104         pid = tsk->pid;
105         if (unlikely(act_log_check(bt, what, sector, pid)))
106                 return;
107
108         /*
109          * A word about the locking here - we disable interrupts to reserve
110          * some space in the relay per-cpu buffer, to prevent an irq
111          * from coming in and stepping on our toes. Once reserved, it's
112          * enough to get preemption disabled to prevent read of this data
113          * before we are through filling it. get_cpu()/put_cpu() does this
114          * for us
115          */
116         local_irq_save(flags);
117
118         if (unlikely(tsk->btrace_seq != blktrace_seq))
119                 trace_note_tsk(bt, tsk);
120
121         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
122         if (t) {
123                 cpu = smp_processor_id();
124                 sequence = per_cpu_ptr(bt->sequence, cpu);
125
126                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
127                 t->sequence = ++(*sequence);
128                 t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);
129                 t->sector = sector;
130                 t->bytes = bytes;
131                 t->action = what;
132                 t->pid = pid;
133                 t->device = bt->dev;
134                 t->cpu = cpu;
135                 t->error = error;
136                 t->pdu_len = pdu_len;
137
138                 if (pdu_len)
139                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
140         }
141
142         local_irq_restore(flags);
143 }
144
145 EXPORT_SYMBOL_GPL(__blk_add_trace);
146
147 static struct dentry *blk_tree_root;
148 static struct mutex blk_tree_mutex;
149 static unsigned int root_users;
150
151 static inline void blk_remove_root(void)
152 {
153         if (blk_tree_root) {
154                 debugfs_remove(blk_tree_root);
155                 blk_tree_root = NULL;
156         }
157 }
158
159 static void blk_remove_tree(struct dentry *dir)
160 {
161         mutex_lock(&blk_tree_mutex);
162         debugfs_remove(dir);
163         if (--root_users == 0)
164                 blk_remove_root();
165         mutex_unlock(&blk_tree_mutex);
166 }
167
168 static struct dentry *blk_create_tree(const char *blk_name)
169 {
170         struct dentry *dir = NULL;
171
172         mutex_lock(&blk_tree_mutex);
173
174         if (!blk_tree_root) {
175                 blk_tree_root = debugfs_create_dir("block", NULL);
176                 if (!blk_tree_root)
177                         goto err;
178         }
179
180         dir = debugfs_create_dir(blk_name, blk_tree_root);
181         if (dir)
182                 root_users++;
183         else
184                 blk_remove_root();
185
186 err:
187         mutex_unlock(&blk_tree_mutex);
188         return dir;
189 }
190
191 static void blk_trace_cleanup(struct blk_trace *bt)
192 {
193         relay_close(bt->rchan);
194         debugfs_remove(bt->dropped_file);
195         blk_remove_tree(bt->dir);
196         free_percpu(bt->sequence);
197         kfree(bt);
198 }
199
200 static int blk_trace_remove(request_queue_t *q)
201 {
202         struct blk_trace *bt;
203
204         bt = xchg(&q->blk_trace, NULL);
205         if (!bt)
206                 return -EINVAL;
207
208         if (bt->trace_state == Blktrace_setup ||
209             bt->trace_state == Blktrace_stopped)
210                 blk_trace_cleanup(bt);
211
212         return 0;
213 }
214
215 static int blk_dropped_open(struct inode *inode, struct file *filp)
216 {
217         filp->private_data = inode->u.generic_ip;
218
219         return 0;
220 }
221
222 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
223                                 size_t count, loff_t *ppos)
224 {
225         struct blk_trace *bt = filp->private_data;
226         char buf[16];
227
228         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
229
230         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
231 }
232
233 static struct file_operations blk_dropped_fops = {
234         .owner =        THIS_MODULE,
235         .open =         blk_dropped_open,
236         .read =         blk_dropped_read,
237 };
238
239 /*
240  * Keep track of how many times we encountered a full subbuffer, to aid
241  * the user space app in telling how many lost events there were.
242  */
243 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
244                                      void *prev_subbuf, size_t prev_padding)
245 {
246         struct blk_trace *bt;
247
248         if (!relay_buf_full(buf))
249                 return 1;
250
251         bt = buf->chan->private_data;
252         atomic_inc(&bt->dropped);
253         return 0;
254 }
255
256 static int blk_remove_buf_file_callback(struct dentry *dentry)
257 {
258         debugfs_remove(dentry);
259         return 0;
260 }
261
262 static struct dentry *blk_create_buf_file_callback(const char *filename,
263                                                    struct dentry *parent,
264                                                    int mode,
265                                                    struct rchan_buf *buf,
266                                                    int *is_global)
267 {
268         return debugfs_create_file(filename, mode, parent, buf,
269                                         &relay_file_operations);
270 }
271
272 static struct rchan_callbacks blk_relay_callbacks = {
273         .subbuf_start           = blk_subbuf_start_callback,
274         .create_buf_file        = blk_create_buf_file_callback,
275         .remove_buf_file        = blk_remove_buf_file_callback,
276 };
277
278 /*
279  * Setup everything required to start tracing
280  */
281 static int blk_trace_setup(request_queue_t *q, struct block_device *bdev,
282                            char __user *arg)
283 {
284         struct blk_user_trace_setup buts;
285         struct blk_trace *old_bt, *bt = NULL;
286         struct dentry *dir = NULL;
287         char b[BDEVNAME_SIZE];
288         int ret, i;
289
290         if (copy_from_user(&buts, arg, sizeof(buts)))
291                 return -EFAULT;
292
293         if (!buts.buf_size || !buts.buf_nr)
294                 return -EINVAL;
295
296         strcpy(buts.name, bdevname(bdev, b));
297
298         /*
299          * some device names have larger paths - convert the slashes
300          * to underscores for this to work as expected
301          */
302         for (i = 0; i < strlen(buts.name); i++)
303                 if (buts.name[i] == '/')
304                         buts.name[i] = '_';
305
306         if (copy_to_user(arg, &buts, sizeof(buts)))
307                 return -EFAULT;
308
309         ret = -ENOMEM;
310         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
311         if (!bt)
312                 goto err;
313
314         bt->sequence = alloc_percpu(unsigned long);
315         if (!bt->sequence)
316                 goto err;
317
318         ret = -ENOENT;
319         dir = blk_create_tree(buts.name);
320         if (!dir)
321                 goto err;
322
323         bt->dir = dir;
324         bt->dev = bdev->bd_dev;
325         atomic_set(&bt->dropped, 0);
326
327         ret = -EIO;
328         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);
329         if (!bt->dropped_file)
330                 goto err;
331
332         bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks);
333         if (!bt->rchan)
334                 goto err;
335         bt->rchan->private_data = bt;
336
337         bt->act_mask = buts.act_mask;
338         if (!bt->act_mask)
339                 bt->act_mask = (u16) -1;
340
341         bt->start_lba = buts.start_lba;
342         bt->end_lba = buts.end_lba;
343         if (!bt->end_lba)
344                 bt->end_lba = -1ULL;
345
346         bt->pid = buts.pid;
347         bt->trace_state = Blktrace_setup;
348
349         ret = -EBUSY;
350         old_bt = xchg(&q->blk_trace, bt);
351         if (old_bt) {
352                 (void) xchg(&q->blk_trace, old_bt);
353                 goto err;
354         }
355
356         return 0;
357 err:
358         if (dir)
359                 blk_remove_tree(dir);
360         if (bt) {
361                 if (bt->dropped_file)
362                         debugfs_remove(bt->dropped_file);
363                 if (bt->sequence)
364                         free_percpu(bt->sequence);
365                 if (bt->rchan)
366                         relay_close(bt->rchan);
367                 kfree(bt);
368         }
369         return ret;
370 }
371
372 static int blk_trace_startstop(request_queue_t *q, int start)
373 {
374         struct blk_trace *bt;
375         int ret;
376
377         if ((bt = q->blk_trace) == NULL)
378                 return -EINVAL;
379
380         /*
381          * For starting a trace, we can transition from a setup or stopped
382          * trace. For stopping a trace, the state must be running
383          */
384         ret = -EINVAL;
385         if (start) {
386                 if (bt->trace_state == Blktrace_setup ||
387                     bt->trace_state == Blktrace_stopped) {
388                         blktrace_seq++;
389                         smp_mb();
390                         bt->trace_state = Blktrace_running;
391                         ret = 0;
392                 }
393         } else {
394                 if (bt->trace_state == Blktrace_running) {
395                         bt->trace_state = Blktrace_stopped;
396                         relay_flush(bt->rchan);
397                         ret = 0;
398                 }
399         }
400
401         return ret;
402 }
403
404 /**
405  * blk_trace_ioctl: - handle the ioctls associated with tracing
406  * @bdev:       the block device
407  * @cmd:        the ioctl cmd
408  * @arg:        the argument data, if any
409  *
410  **/
411 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
412 {
413         request_queue_t *q;
414         int ret, start = 0;
415
416         q = bdev_get_queue(bdev);
417         if (!q)
418                 return -ENXIO;
419
420         mutex_lock(&bdev->bd_mutex);
421
422         switch (cmd) {
423         case BLKTRACESETUP:
424                 ret = blk_trace_setup(q, bdev, arg);
425                 break;
426         case BLKTRACESTART:
427                 start = 1;
428         case BLKTRACESTOP:
429                 ret = blk_trace_startstop(q, start);
430                 break;
431         case BLKTRACETEARDOWN:
432                 ret = blk_trace_remove(q);
433                 break;
434         default:
435                 ret = -ENOTTY;
436                 break;
437         }
438
439         mutex_unlock(&bdev->bd_mutex);
440         return ret;
441 }
442
443 /**
444  * blk_trace_shutdown: - stop and cleanup trace structures
445  * @q:    the request queue associated with the device
446  *
447  **/
448 void blk_trace_shutdown(request_queue_t *q)
449 {
450         blk_trace_startstop(q, 0);
451         blk_trace_remove(q);
452 }
453
454 /*
455  * Average offset over two calls to sched_clock() with a gettimeofday()
456  * in the middle
457  */
458 static void blk_check_time(unsigned long long *t)
459 {
460         unsigned long long a, b;
461         struct timeval tv;
462
463         a = sched_clock();
464         do_gettimeofday(&tv);
465         b = sched_clock();
466
467         *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
468         *t -= (a + b) / 2;
469 }
470
471 static void blk_trace_check_cpu_time(void *data)
472 {
473         unsigned long long *t;
474         int cpu = get_cpu();
475
476         t = &per_cpu(blk_trace_cpu_offset, cpu);
477
478         /*
479          * Just call it twice, hopefully the second call will be cache hot
480          * and a little more precise
481          */
482         blk_check_time(t);
483         blk_check_time(t);
484
485         put_cpu();
486 }
487
488 /*
489  * Call blk_trace_check_cpu_time() on each CPU to calibrate our inter-CPU
490  * timings
491  */
492 static void blk_trace_calibrate_offsets(void)
493 {
494         unsigned long flags;
495
496         smp_call_function(blk_trace_check_cpu_time, NULL, 1, 1);
497         local_irq_save(flags);
498         blk_trace_check_cpu_time(NULL);
499         local_irq_restore(flags);
500 }
501
502 static void blk_trace_set_ht_offsets(void)
503 {
504 #if defined(CONFIG_SCHED_SMT)
505         int cpu, i;
506
507         /*
508          * now make sure HT siblings have the same time offset
509          */
510         preempt_disable();
511         for_each_online_cpu(cpu) {
512                 unsigned long long *cpu_off, *sibling_off;
513
514                 for_each_cpu_mask(i, cpu_sibling_map[cpu]) {
515                         if (i == cpu)
516                                 continue;
517
518                         cpu_off = &per_cpu(blk_trace_cpu_offset, cpu);
519                         sibling_off = &per_cpu(blk_trace_cpu_offset, i);
520                         *sibling_off = *cpu_off;
521                 }
522         }
523         preempt_enable();
524 #endif
525 }
526
527 static __init int blk_trace_init(void)
528 {
529         mutex_init(&blk_tree_mutex);
530         blk_trace_calibrate_offsets();
531         blk_trace_set_ht_offsets();
532
533         return 0;
534 }
535
536 module_init(blk_trace_init);
537