block: remove support for bio remapping from ->make_request
[linux-3.10.git] / drivers / md / linear.c
1 /*
2    linear.c : Multiple Devices driver for Linux
3               Copyright (C) 1994-96 Marc ZYNGIER
4               <zyngier@ufr-info-p7.ibp.fr> or
5               <maz@gloups.fdn.fr>
6
7    Linear mode management functions.
8
9    This program is free software; you can redistribute it and/or modify
10    it under the terms of the GNU General Public License as published by
11    the Free Software Foundation; either version 2, or (at your option)
12    any later version.
13    
14    You should have received a copy of the GNU General Public License
15    (for example /usr/src/linux/COPYING); if not, write to the Free
16    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
17 */
18
19 #include <linux/blkdev.h>
20 #include <linux/raid/md_u.h>
21 #include <linux/seq_file.h>
22 #include <linux/slab.h>
23 #include "md.h"
24 #include "linear.h"
25
26 /*
27  * find which device holds a particular offset 
28  */
29 static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
30 {
31         int lo, mid, hi;
32         linear_conf_t *conf;
33
34         lo = 0;
35         hi = mddev->raid_disks - 1;
36         conf = rcu_dereference(mddev->private);
37
38         /*
39          * Binary Search
40          */
41
42         while (hi > lo) {
43
44                 mid = (hi + lo) / 2;
45                 if (sector < conf->disks[mid].end_sector)
46                         hi = mid;
47                 else
48                         lo = mid + 1;
49         }
50
51         return conf->disks + lo;
52 }
53
54 /**
55  *      linear_mergeable_bvec -- tell bio layer if two requests can be merged
56  *      @q: request queue
57  *      @bvm: properties of new bio
58  *      @biovec: the request that could be merged to it.
59  *
60  *      Return amount of bytes we can take at this offset
61  */
62 static int linear_mergeable_bvec(struct request_queue *q,
63                                  struct bvec_merge_data *bvm,
64                                  struct bio_vec *biovec)
65 {
66         mddev_t *mddev = q->queuedata;
67         dev_info_t *dev0;
68         unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
69         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
70
71         rcu_read_lock();
72         dev0 = which_dev(mddev, sector);
73         maxsectors = dev0->end_sector - sector;
74         rcu_read_unlock();
75
76         if (maxsectors < bio_sectors)
77                 maxsectors = 0;
78         else
79                 maxsectors -= bio_sectors;
80
81         if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
82                 return biovec->bv_len;
83         /* The bytes available at this offset could be really big,
84          * so we cap at 2^31 to avoid overflow */
85         if (maxsectors > (1 << (31-9)))
86                 return 1<<31;
87         return maxsectors << 9;
88 }
89
90 static int linear_congested(void *data, int bits)
91 {
92         mddev_t *mddev = data;
93         linear_conf_t *conf;
94         int i, ret = 0;
95
96         if (mddev_congested(mddev, bits))
97                 return 1;
98
99         rcu_read_lock();
100         conf = rcu_dereference(mddev->private);
101
102         for (i = 0; i < mddev->raid_disks && !ret ; i++) {
103                 struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
104                 ret |= bdi_congested(&q->backing_dev_info, bits);
105         }
106
107         rcu_read_unlock();
108         return ret;
109 }
110
111 static sector_t linear_size(mddev_t *mddev, sector_t sectors, int raid_disks)
112 {
113         linear_conf_t *conf;
114         sector_t array_sectors;
115
116         rcu_read_lock();
117         conf = rcu_dereference(mddev->private);
118         WARN_ONCE(sectors || raid_disks,
119                   "%s does not support generic reshape\n", __func__);
120         array_sectors = conf->array_sectors;
121         rcu_read_unlock();
122
123         return array_sectors;
124 }
125
126 static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
127 {
128         linear_conf_t *conf;
129         mdk_rdev_t *rdev;
130         int i, cnt;
131
132         conf = kzalloc (sizeof (*conf) + raid_disks*sizeof(dev_info_t),
133                         GFP_KERNEL);
134         if (!conf)
135                 return NULL;
136
137         cnt = 0;
138         conf->array_sectors = 0;
139
140         list_for_each_entry(rdev, &mddev->disks, same_set) {
141                 int j = rdev->raid_disk;
142                 dev_info_t *disk = conf->disks + j;
143                 sector_t sectors;
144
145                 if (j < 0 || j >= raid_disks || disk->rdev) {
146                         printk(KERN_ERR "md/linear:%s: disk numbering problem. Aborting!\n",
147                                mdname(mddev));
148                         goto out;
149                 }
150
151                 disk->rdev = rdev;
152                 if (mddev->chunk_sectors) {
153                         sectors = rdev->sectors;
154                         sector_div(sectors, mddev->chunk_sectors);
155                         rdev->sectors = sectors * mddev->chunk_sectors;
156                 }
157
158                 disk_stack_limits(mddev->gendisk, rdev->bdev,
159                                   rdev->data_offset << 9);
160                 /* as we don't honour merge_bvec_fn, we must never risk
161                  * violating it, so limit max_segments to 1 lying within
162                  * a single page.
163                  */
164                 if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
165                         blk_queue_max_segments(mddev->queue, 1);
166                         blk_queue_segment_boundary(mddev->queue,
167                                                    PAGE_CACHE_SIZE - 1);
168                 }
169
170                 conf->array_sectors += rdev->sectors;
171                 cnt++;
172
173         }
174         if (cnt != raid_disks) {
175                 printk(KERN_ERR "md/linear:%s: not enough drives present. Aborting!\n",
176                        mdname(mddev));
177                 goto out;
178         }
179
180         /*
181          * Here we calculate the device offsets.
182          */
183         conf->disks[0].end_sector = conf->disks[0].rdev->sectors;
184
185         for (i = 1; i < raid_disks; i++)
186                 conf->disks[i].end_sector =
187                         conf->disks[i-1].end_sector +
188                         conf->disks[i].rdev->sectors;
189
190         return conf;
191
192 out:
193         kfree(conf);
194         return NULL;
195 }
196
197 static int linear_run (mddev_t *mddev)
198 {
199         linear_conf_t *conf;
200
201         if (md_check_no_bitmap(mddev))
202                 return -EINVAL;
203         conf = linear_conf(mddev, mddev->raid_disks);
204
205         if (!conf)
206                 return 1;
207         mddev->private = conf;
208         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
209
210         blk_queue_merge_bvec(mddev->queue, linear_mergeable_bvec);
211         mddev->queue->backing_dev_info.congested_fn = linear_congested;
212         mddev->queue->backing_dev_info.congested_data = mddev;
213         return md_integrity_register(mddev);
214 }
215
216 static int linear_add(mddev_t *mddev, mdk_rdev_t *rdev)
217 {
218         /* Adding a drive to a linear array allows the array to grow.
219          * It is permitted if the new drive has a matching superblock
220          * already on it, with raid_disk equal to raid_disks.
221          * It is achieved by creating a new linear_private_data structure
222          * and swapping it in in-place of the current one.
223          * The current one is never freed until the array is stopped.
224          * This avoids races.
225          */
226         linear_conf_t *newconf, *oldconf;
227
228         if (rdev->saved_raid_disk != mddev->raid_disks)
229                 return -EINVAL;
230
231         rdev->raid_disk = rdev->saved_raid_disk;
232
233         newconf = linear_conf(mddev,mddev->raid_disks+1);
234
235         if (!newconf)
236                 return -ENOMEM;
237
238         oldconf = rcu_dereference(mddev->private);
239         mddev->raid_disks++;
240         rcu_assign_pointer(mddev->private, newconf);
241         md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
242         set_capacity(mddev->gendisk, mddev->array_sectors);
243         revalidate_disk(mddev->gendisk);
244         kfree_rcu(oldconf, rcu);
245         return 0;
246 }
247
248 static int linear_stop (mddev_t *mddev)
249 {
250         linear_conf_t *conf = mddev->private;
251
252         /*
253          * We do not require rcu protection here since
254          * we hold reconfig_mutex for both linear_add and
255          * linear_stop, so they cannot race.
256          * We should make sure any old 'conf's are properly
257          * freed though.
258          */
259         rcu_barrier();
260         blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
261         kfree(conf);
262         mddev->private = NULL;
263
264         return 0;
265 }
266
267 static void linear_make_request (mddev_t *mddev, struct bio *bio)
268 {
269         dev_info_t *tmp_dev;
270         sector_t start_sector;
271
272         if (unlikely(bio->bi_rw & REQ_FLUSH)) {
273                 md_flush_request(mddev, bio);
274                 return;
275         }
276
277         rcu_read_lock();
278         tmp_dev = which_dev(mddev, bio->bi_sector);
279         start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
280
281
282         if (unlikely(bio->bi_sector >= (tmp_dev->end_sector)
283                      || (bio->bi_sector < start_sector))) {
284                 char b[BDEVNAME_SIZE];
285
286                 printk(KERN_ERR
287                        "md/linear:%s: make_request: Sector %llu out of bounds on "
288                        "dev %s: %llu sectors, offset %llu\n",
289                        mdname(mddev),
290                        (unsigned long long)bio->bi_sector,
291                        bdevname(tmp_dev->rdev->bdev, b),
292                        (unsigned long long)tmp_dev->rdev->sectors,
293                        (unsigned long long)start_sector);
294                 rcu_read_unlock();
295                 bio_io_error(bio);
296                 return;
297         }
298         if (unlikely(bio->bi_sector + (bio->bi_size >> 9) >
299                      tmp_dev->end_sector)) {
300                 /* This bio crosses a device boundary, so we have to
301                  * split it.
302                  */
303                 struct bio_pair *bp;
304                 sector_t end_sector = tmp_dev->end_sector;
305
306                 rcu_read_unlock();
307
308                 bp = bio_split(bio, end_sector - bio->bi_sector);
309
310                 linear_make_request(mddev, &bp->bio1);
311                 linear_make_request(mddev, &bp->bio2);
312                 bio_pair_release(bp);
313                 return;
314         }
315                     
316         bio->bi_bdev = tmp_dev->rdev->bdev;
317         bio->bi_sector = bio->bi_sector - start_sector
318                 + tmp_dev->rdev->data_offset;
319         rcu_read_unlock();
320         generic_make_request(bio);
321 }
322
323 static void linear_status (struct seq_file *seq, mddev_t *mddev)
324 {
325
326         seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
327 }
328
329
330 static struct mdk_personality linear_personality =
331 {
332         .name           = "linear",
333         .level          = LEVEL_LINEAR,
334         .owner          = THIS_MODULE,
335         .make_request   = linear_make_request,
336         .run            = linear_run,
337         .stop           = linear_stop,
338         .status         = linear_status,
339         .hot_add_disk   = linear_add,
340         .size           = linear_size,
341 };
342
343 static int __init linear_init (void)
344 {
345         return register_md_personality (&linear_personality);
346 }
347
348 static void linear_exit (void)
349 {
350         unregister_md_personality (&linear_personality);
351 }
352
353
354 module_init(linear_init);
355 module_exit(linear_exit);
356 MODULE_LICENSE("GPL");
357 MODULE_DESCRIPTION("Linear device concatenation personality for MD");
358 MODULE_ALIAS("md-personality-1"); /* LINEAR - deprecated*/
359 MODULE_ALIAS("md-linear");
360 MODULE_ALIAS("md-level--1");