[ALSA] sparc dbri removal of DBRI_NO_INTS
[linux-2.6.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[5] __read_mostly = { 0, BLK_TC_ACT(BLK_TC_BARRIER), BLK_TC_ACT(BLK_TC_SYNC), 0, BLK_TC_ACT(BLK_TC_AHEAD) };
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 #define trace_ahead_bit(rw)     \
83         (((rw) & (1 << BIO_RW_AHEAD)) << (2 - BIO_RW_AHEAD))
84
85 /*
86  * The worker for the various blk_add_trace*() types. Fills out a
87  * blk_io_trace structure and places it in a per-cpu subbuffer.
88  */
89 void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
90                      int rw, u32 what, int error, int pdu_len, void *pdu_data)
91 {
92         struct task_struct *tsk = current;
93         struct blk_io_trace *t;
94         unsigned long flags;
95         unsigned long *sequence;
96         pid_t pid;
97         int cpu;
98
99         if (unlikely(bt->trace_state != Blktrace_running))
100                 return;
101
102         what |= ddir_act[rw & WRITE];
103         what |= bio_act[trace_barrier_bit(rw)];
104         what |= bio_act[trace_sync_bit(rw)];
105         what |= bio_act[trace_ahead_bit(rw)];
106
107         pid = tsk->pid;
108         if (unlikely(act_log_check(bt, what, sector, pid)))
109                 return;
110
111         /*
112          * A word about the locking here - we disable interrupts to reserve
113          * some space in the relay per-cpu buffer, to prevent an irq
114          * from coming in and stepping on our toes. Once reserved, it's
115          * enough to get preemption disabled to prevent read of this data
116          * before we are through filling it. get_cpu()/put_cpu() does this
117          * for us
118          */
119         local_irq_save(flags);
120
121         if (unlikely(tsk->btrace_seq != blktrace_seq))
122                 trace_note_tsk(bt, tsk);
123
124         t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len);
125         if (t) {
126                 cpu = smp_processor_id();
127                 sequence = per_cpu_ptr(bt->sequence, cpu);
128
129                 t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
130                 t->sequence = ++(*sequence);
131                 t->time = sched_clock() - per_cpu(blk_trace_cpu_offset, cpu);
132                 t->sector = sector;
133                 t->bytes = bytes;
134                 t->action = what;
135                 t->pid = pid;
136                 t->device = bt->dev;
137                 t->cpu = cpu;
138                 t->error = error;
139                 t->pdu_len = pdu_len;
140
141                 if (pdu_len)
142                         memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
143         }
144
145         local_irq_restore(flags);
146 }
147
148 EXPORT_SYMBOL_GPL(__blk_add_trace);
149
150 static struct dentry *blk_tree_root;
151 static struct mutex blk_tree_mutex;
152 static unsigned int root_users;
153
154 static inline void blk_remove_root(void)
155 {
156         if (blk_tree_root) {
157                 debugfs_remove(blk_tree_root);
158                 blk_tree_root = NULL;
159         }
160 }
161
162 static void blk_remove_tree(struct dentry *dir)
163 {
164         mutex_lock(&blk_tree_mutex);
165         debugfs_remove(dir);
166         if (--root_users == 0)
167                 blk_remove_root();
168         mutex_unlock(&blk_tree_mutex);
169 }
170
171 static struct dentry *blk_create_tree(const char *blk_name)
172 {
173         struct dentry *dir = NULL;
174
175         mutex_lock(&blk_tree_mutex);
176
177         if (!blk_tree_root) {
178                 blk_tree_root = debugfs_create_dir("block", NULL);
179                 if (!blk_tree_root)
180                         goto err;
181         }
182
183         dir = debugfs_create_dir(blk_name, blk_tree_root);
184         if (dir)
185                 root_users++;
186         else
187                 blk_remove_root();
188
189 err:
190         mutex_unlock(&blk_tree_mutex);
191         return dir;
192 }
193
194 static void blk_trace_cleanup(struct blk_trace *bt)
195 {
196         relay_close(bt->rchan);
197         debugfs_remove(bt->dropped_file);
198         blk_remove_tree(bt->dir);
199         free_percpu(bt->sequence);
200         kfree(bt);
201 }
202
203 static int blk_trace_remove(request_queue_t *q)
204 {
205         struct blk_trace *bt;
206
207         bt = xchg(&q->blk_trace, NULL);
208         if (!bt)
209                 return -EINVAL;
210
211         if (bt->trace_state == Blktrace_setup ||
212             bt->trace_state == Blktrace_stopped)
213                 blk_trace_cleanup(bt);
214
215         return 0;
216 }
217
218 static int blk_dropped_open(struct inode *inode, struct file *filp)
219 {
220         filp->private_data = inode->u.generic_ip;
221
222         return 0;
223 }
224
225 static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
226                                 size_t count, loff_t *ppos)
227 {
228         struct blk_trace *bt = filp->private_data;
229         char buf[16];
230
231         snprintf(buf, sizeof(buf), "%u\n", atomic_read(&bt->dropped));
232
233         return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
234 }
235
236 static struct file_operations blk_dropped_fops = {
237         .owner =        THIS_MODULE,
238         .open =         blk_dropped_open,
239         .read =         blk_dropped_read,
240 };
241
242 /*
243  * Keep track of how many times we encountered a full subbuffer, to aid
244  * the user space app in telling how many lost events there were.
245  */
246 static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
247                                      void *prev_subbuf, size_t prev_padding)
248 {
249         struct blk_trace *bt;
250
251         if (!relay_buf_full(buf))
252                 return 1;
253
254         bt = buf->chan->private_data;
255         atomic_inc(&bt->dropped);
256         return 0;
257 }
258
259 static int blk_remove_buf_file_callback(struct dentry *dentry)
260 {
261         debugfs_remove(dentry);
262         return 0;
263 }
264
265 static struct dentry *blk_create_buf_file_callback(const char *filename,
266                                                    struct dentry *parent,
267                                                    int mode,
268                                                    struct rchan_buf *buf,
269                                                    int *is_global)
270 {
271         return debugfs_create_file(filename, mode, parent, buf,
272                                         &relay_file_operations);
273 }
274
275 static struct rchan_callbacks blk_relay_callbacks = {
276         .subbuf_start           = blk_subbuf_start_callback,
277         .create_buf_file        = blk_create_buf_file_callback,
278         .remove_buf_file        = blk_remove_buf_file_callback,
279 };
280
281 /*
282  * Setup everything required to start tracing
283  */
284 static int blk_trace_setup(request_queue_t *q, struct block_device *bdev,
285                            char __user *arg)
286 {
287         struct blk_user_trace_setup buts;
288         struct blk_trace *old_bt, *bt = NULL;
289         struct dentry *dir = NULL;
290         char b[BDEVNAME_SIZE];
291         int ret, i;
292
293         if (copy_from_user(&buts, arg, sizeof(buts)))
294                 return -EFAULT;
295
296         if (!buts.buf_size || !buts.buf_nr)
297                 return -EINVAL;
298
299         strcpy(buts.name, bdevname(bdev, b));
300
301         /*
302          * some device names have larger paths - convert the slashes
303          * to underscores for this to work as expected
304          */
305         for (i = 0; i < strlen(buts.name); i++)
306                 if (buts.name[i] == '/')
307                         buts.name[i] = '_';
308
309         if (copy_to_user(arg, &buts, sizeof(buts)))
310                 return -EFAULT;
311
312         ret = -ENOMEM;
313         bt = kzalloc(sizeof(*bt), GFP_KERNEL);
314         if (!bt)
315                 goto err;
316
317         bt->sequence = alloc_percpu(unsigned long);
318         if (!bt->sequence)
319                 goto err;
320
321         ret = -ENOENT;
322         dir = blk_create_tree(buts.name);
323         if (!dir)
324                 goto err;
325
326         bt->dir = dir;
327         bt->dev = bdev->bd_dev;
328         atomic_set(&bt->dropped, 0);
329
330         ret = -EIO;
331         bt->dropped_file = debugfs_create_file("dropped", 0444, dir, bt, &blk_dropped_fops);
332         if (!bt->dropped_file)
333                 goto err;
334
335         bt->rchan = relay_open("trace", dir, buts.buf_size, buts.buf_nr, &blk_relay_callbacks);
336         if (!bt->rchan)
337                 goto err;
338         bt->rchan->private_data = bt;
339
340         bt->act_mask = buts.act_mask;
341         if (!bt->act_mask)
342                 bt->act_mask = (u16) -1;
343
344         bt->start_lba = buts.start_lba;
345         bt->end_lba = buts.end_lba;
346         if (!bt->end_lba)
347                 bt->end_lba = -1ULL;
348
349         bt->pid = buts.pid;
350         bt->trace_state = Blktrace_setup;
351
352         ret = -EBUSY;
353         old_bt = xchg(&q->blk_trace, bt);
354         if (old_bt) {
355                 (void) xchg(&q->blk_trace, old_bt);
356                 goto err;
357         }
358
359         return 0;
360 err:
361         if (dir)
362                 blk_remove_tree(dir);
363         if (bt) {
364                 if (bt->dropped_file)
365                         debugfs_remove(bt->dropped_file);
366                 if (bt->sequence)
367                         free_percpu(bt->sequence);
368                 if (bt->rchan)
369                         relay_close(bt->rchan);
370                 kfree(bt);
371         }
372         return ret;
373 }
374
375 static int blk_trace_startstop(request_queue_t *q, int start)
376 {
377         struct blk_trace *bt;
378         int ret;
379
380         if ((bt = q->blk_trace) == NULL)
381                 return -EINVAL;
382
383         /*
384          * For starting a trace, we can transition from a setup or stopped
385          * trace. For stopping a trace, the state must be running
386          */
387         ret = -EINVAL;
388         if (start) {
389                 if (bt->trace_state == Blktrace_setup ||
390                     bt->trace_state == Blktrace_stopped) {
391                         blktrace_seq++;
392                         smp_mb();
393                         bt->trace_state = Blktrace_running;
394                         ret = 0;
395                 }
396         } else {
397                 if (bt->trace_state == Blktrace_running) {
398                         bt->trace_state = Blktrace_stopped;
399                         relay_flush(bt->rchan);
400                         ret = 0;
401                 }
402         }
403
404         return ret;
405 }
406
407 /**
408  * blk_trace_ioctl: - handle the ioctls associated with tracing
409  * @bdev:       the block device
410  * @cmd:        the ioctl cmd
411  * @arg:        the argument data, if any
412  *
413  **/
414 int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
415 {
416         request_queue_t *q;
417         int ret, start = 0;
418
419         q = bdev_get_queue(bdev);
420         if (!q)
421                 return -ENXIO;
422
423         mutex_lock(&bdev->bd_mutex);
424
425         switch (cmd) {
426         case BLKTRACESETUP:
427                 ret = blk_trace_setup(q, bdev, arg);
428                 break;
429         case BLKTRACESTART:
430                 start = 1;
431         case BLKTRACESTOP:
432                 ret = blk_trace_startstop(q, start);
433                 break;
434         case BLKTRACETEARDOWN:
435                 ret = blk_trace_remove(q);
436                 break;
437         default:
438                 ret = -ENOTTY;
439                 break;
440         }
441
442         mutex_unlock(&bdev->bd_mutex);
443         return ret;
444 }
445
446 /**
447  * blk_trace_shutdown: - stop and cleanup trace structures
448  * @q:    the request queue associated with the device
449  *
450  **/
451 void blk_trace_shutdown(request_queue_t *q)
452 {
453         blk_trace_startstop(q, 0);
454         blk_trace_remove(q);
455 }
456
457 /*
458  * Average offset over two calls to sched_clock() with a gettimeofday()
459  * in the middle
460  */
461 static void blk_check_time(unsigned long long *t)
462 {
463         unsigned long long a, b;
464         struct timeval tv;
465
466         a = sched_clock();
467         do_gettimeofday(&tv);
468         b = sched_clock();
469
470         *t = tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
471         *t -= (a + b) / 2;
472 }
473
474 static void blk_trace_check_cpu_time(void *data)
475 {
476         unsigned long long *t;
477         int cpu = get_cpu();
478
479         t = &per_cpu(blk_trace_cpu_offset, cpu);
480
481         /*
482          * Just call it twice, hopefully the second call will be cache hot
483          * and a little more precise
484          */
485         blk_check_time(t);
486         blk_check_time(t);
487
488         put_cpu();
489 }
490
491 /*
492  * Call blk_trace_check_cpu_time() on each CPU to calibrate our inter-CPU
493  * timings
494  */
495 static void blk_trace_calibrate_offsets(void)
496 {
497         unsigned long flags;
498
499         smp_call_function(blk_trace_check_cpu_time, NULL, 1, 1);
500         local_irq_save(flags);
501         blk_trace_check_cpu_time(NULL);
502         local_irq_restore(flags);
503 }
504
505 static void blk_trace_set_ht_offsets(void)
506 {
507 #if defined(CONFIG_SCHED_SMT)
508         int cpu, i;
509
510         /*
511          * now make sure HT siblings have the same time offset
512          */
513         preempt_disable();
514         for_each_online_cpu(cpu) {
515                 unsigned long long *cpu_off, *sibling_off;
516
517                 for_each_cpu_mask(i, cpu_sibling_map[cpu]) {
518                         if (i == cpu)
519                                 continue;
520
521                         cpu_off = &per_cpu(blk_trace_cpu_offset, cpu);
522                         sibling_off = &per_cpu(blk_trace_cpu_offset, i);
523                         *sibling_off = *cpu_off;
524                 }
525         }
526         preempt_enable();
527 #endif
528 }
529
530 static __init int blk_trace_init(void)
531 {
532         mutex_init(&blk_tree_mutex);
533         blk_trace_calibrate_offsets();
534         blk_trace_set_ht_offsets();
535
536         return 0;
537 }
538
539 module_init(blk_trace_init);
540