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Linux/fs/nilfs2/segbuf.c

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  1 /*
  2  * segbuf.c - NILFS segment buffer
  3  *
  4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public License
 17  * along with this program; if not, write to the Free Software
 18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 19  *
 20  * Written by Ryusuke Konishi <ryusuke@osrg.net>
 21  *
 22  */
 23 
 24 #include <linux/buffer_head.h>
 25 #include <linux/writeback.h>
 26 #include <linux/crc32.h>
 27 #include <linux/backing-dev.h>
 28 #include <linux/slab.h>
 29 #include "page.h"
 30 #include "segbuf.h"
 31 
 32 
 33 struct nilfs_write_info {
 34         struct the_nilfs       *nilfs;
 35         struct bio             *bio;
 36         int                     start, end; /* The region to be submitted */
 37         int                     rest_blocks;
 38         int                     max_pages;
 39         int                     nr_vecs;
 40         sector_t                blocknr;
 41 };
 42 
 43 static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
 44                               struct the_nilfs *nilfs);
 45 static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf);
 46 
 47 struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
 48 {
 49         struct nilfs_segment_buffer *segbuf;
 50 
 51         segbuf = kmem_cache_alloc(nilfs_segbuf_cachep, GFP_NOFS);
 52         if (unlikely(!segbuf))
 53                 return NULL;
 54 
 55         segbuf->sb_super = sb;
 56         INIT_LIST_HEAD(&segbuf->sb_list);
 57         INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
 58         INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
 59         segbuf->sb_super_root = NULL;
 60 
 61         init_completion(&segbuf->sb_bio_event);
 62         atomic_set(&segbuf->sb_err, 0);
 63         segbuf->sb_nbio = 0;
 64 
 65         return segbuf;
 66 }
 67 
 68 void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
 69 {
 70         kmem_cache_free(nilfs_segbuf_cachep, segbuf);
 71 }
 72 
 73 void nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
 74                      unsigned long offset, struct the_nilfs *nilfs)
 75 {
 76         segbuf->sb_segnum = segnum;
 77         nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
 78                                 &segbuf->sb_fseg_end);
 79 
 80         segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
 81         segbuf->sb_rest_blocks =
 82                 segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
 83 }
 84 
 85 /**
 86  * nilfs_segbuf_map_cont - map a new log behind a given log
 87  * @segbuf: new segment buffer
 88  * @prev: segment buffer containing a log to be continued
 89  */
 90 void nilfs_segbuf_map_cont(struct nilfs_segment_buffer *segbuf,
 91                            struct nilfs_segment_buffer *prev)
 92 {
 93         segbuf->sb_segnum = prev->sb_segnum;
 94         segbuf->sb_fseg_start = prev->sb_fseg_start;
 95         segbuf->sb_fseg_end = prev->sb_fseg_end;
 96         segbuf->sb_pseg_start = prev->sb_pseg_start + prev->sb_sum.nblocks;
 97         segbuf->sb_rest_blocks =
 98                 segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
 99 }
100 
101 void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
102                                   __u64 nextnum, struct the_nilfs *nilfs)
103 {
104         segbuf->sb_nextnum = nextnum;
105         segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
106 }
107 
108 int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
109 {
110         struct buffer_head *bh;
111 
112         bh = sb_getblk(segbuf->sb_super,
113                        segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
114         if (unlikely(!bh))
115                 return -ENOMEM;
116 
117         nilfs_segbuf_add_segsum_buffer(segbuf, bh);
118         return 0;
119 }
120 
121 int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
122                                 struct buffer_head **bhp)
123 {
124         struct buffer_head *bh;
125 
126         bh = sb_getblk(segbuf->sb_super,
127                        segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
128         if (unlikely(!bh))
129                 return -ENOMEM;
130 
131         nilfs_segbuf_add_payload_buffer(segbuf, bh);
132         *bhp = bh;
133         return 0;
134 }
135 
136 int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
137                        time_t ctime, __u64 cno)
138 {
139         int err;
140 
141         segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
142         err = nilfs_segbuf_extend_segsum(segbuf);
143         if (unlikely(err))
144                 return err;
145 
146         segbuf->sb_sum.flags = flags;
147         segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
148         segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
149         segbuf->sb_sum.ctime = ctime;
150         segbuf->sb_sum.cno = cno;
151         return 0;
152 }
153 
154 /*
155  * Setup segment summary
156  */
157 void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
158 {
159         struct nilfs_segment_summary *raw_sum;
160         struct buffer_head *bh_sum;
161 
162         bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
163                             struct buffer_head, b_assoc_buffers);
164         raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;
165 
166         raw_sum->ss_magic    = cpu_to_le32(NILFS_SEGSUM_MAGIC);
167         raw_sum->ss_bytes    = cpu_to_le16(sizeof(*raw_sum));
168         raw_sum->ss_flags    = cpu_to_le16(segbuf->sb_sum.flags);
169         raw_sum->ss_seq      = cpu_to_le64(segbuf->sb_sum.seg_seq);
170         raw_sum->ss_create   = cpu_to_le64(segbuf->sb_sum.ctime);
171         raw_sum->ss_next     = cpu_to_le64(segbuf->sb_sum.next);
172         raw_sum->ss_nblocks  = cpu_to_le32(segbuf->sb_sum.nblocks);
173         raw_sum->ss_nfinfo   = cpu_to_le32(segbuf->sb_sum.nfinfo);
174         raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
175         raw_sum->ss_pad      = 0;
176         raw_sum->ss_cno      = cpu_to_le64(segbuf->sb_sum.cno);
177 }
178 
179 /*
180  * CRC calculation routines
181  */
182 static void
183 nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf, u32 seed)
184 {
185         struct buffer_head *bh;
186         struct nilfs_segment_summary *raw_sum;
187         unsigned long size, bytes = segbuf->sb_sum.sumbytes;
188         u32 crc;
189 
190         bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
191                         b_assoc_buffers);
192 
193         raw_sum = (struct nilfs_segment_summary *)bh->b_data;
194         size = min_t(unsigned long, bytes, bh->b_size);
195         crc = crc32_le(seed,
196                        (unsigned char *)raw_sum +
197                        sizeof(raw_sum->ss_datasum) + sizeof(raw_sum->ss_sumsum),
198                        size - (sizeof(raw_sum->ss_datasum) +
199                                sizeof(raw_sum->ss_sumsum)));
200 
201         list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
202                                      b_assoc_buffers) {
203                 bytes -= size;
204                 size = min_t(unsigned long, bytes, bh->b_size);
205                 crc = crc32_le(crc, bh->b_data, size);
206         }
207         raw_sum->ss_sumsum = cpu_to_le32(crc);
208 }
209 
210 static void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
211                                           u32 seed)
212 {
213         struct buffer_head *bh;
214         struct nilfs_segment_summary *raw_sum;
215         void *kaddr;
216         u32 crc;
217 
218         bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
219                         b_assoc_buffers);
220         raw_sum = (struct nilfs_segment_summary *)bh->b_data;
221         crc = crc32_le(seed,
222                        (unsigned char *)raw_sum + sizeof(raw_sum->ss_datasum),
223                        bh->b_size - sizeof(raw_sum->ss_datasum));
224 
225         list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
226                                      b_assoc_buffers) {
227                 crc = crc32_le(crc, bh->b_data, bh->b_size);
228         }
229         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
230                 kaddr = kmap_atomic(bh->b_page);
231                 crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
232                 kunmap_atomic(kaddr);
233         }
234         raw_sum->ss_datasum = cpu_to_le32(crc);
235 }
236 
237 static void
238 nilfs_segbuf_fill_in_super_root_crc(struct nilfs_segment_buffer *segbuf,
239                                     u32 seed)
240 {
241         struct nilfs_super_root *raw_sr;
242         struct the_nilfs *nilfs = segbuf->sb_super->s_fs_info;
243         unsigned srsize;
244         u32 crc;
245 
246         raw_sr = (struct nilfs_super_root *)segbuf->sb_super_root->b_data;
247         srsize = NILFS_SR_BYTES(nilfs->ns_inode_size);
248         crc = crc32_le(seed,
249                        (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
250                        srsize - sizeof(raw_sr->sr_sum));
251         raw_sr->sr_sum = cpu_to_le32(crc);
252 }
253 
254 static void nilfs_release_buffers(struct list_head *list)
255 {
256         struct buffer_head *bh, *n;
257 
258         list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
259                 list_del_init(&bh->b_assoc_buffers);
260                 brelse(bh);
261         }
262 }
263 
264 static void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)
265 {
266         nilfs_release_buffers(&segbuf->sb_segsum_buffers);
267         nilfs_release_buffers(&segbuf->sb_payload_buffers);
268         segbuf->sb_super_root = NULL;
269 }
270 
271 /*
272  * Iterators for segment buffers
273  */
274 void nilfs_clear_logs(struct list_head *logs)
275 {
276         struct nilfs_segment_buffer *segbuf;
277 
278         list_for_each_entry(segbuf, logs, sb_list)
279                 nilfs_segbuf_clear(segbuf);
280 }
281 
282 void nilfs_truncate_logs(struct list_head *logs,
283                          struct nilfs_segment_buffer *last)
284 {
285         struct nilfs_segment_buffer *n, *segbuf;
286 
287         segbuf = list_prepare_entry(last, logs, sb_list);
288         list_for_each_entry_safe_continue(segbuf, n, logs, sb_list) {
289                 list_del_init(&segbuf->sb_list);
290                 nilfs_segbuf_clear(segbuf);
291                 nilfs_segbuf_free(segbuf);
292         }
293 }
294 
295 int nilfs_write_logs(struct list_head *logs, struct the_nilfs *nilfs)
296 {
297         struct nilfs_segment_buffer *segbuf;
298         int ret = 0;
299 
300         list_for_each_entry(segbuf, logs, sb_list) {
301                 ret = nilfs_segbuf_write(segbuf, nilfs);
302                 if (ret)
303                         break;
304         }
305         return ret;
306 }
307 
308 int nilfs_wait_on_logs(struct list_head *logs)
309 {
310         struct nilfs_segment_buffer *segbuf;
311         int err, ret = 0;
312 
313         list_for_each_entry(segbuf, logs, sb_list) {
314                 err = nilfs_segbuf_wait(segbuf);
315                 if (err && !ret)
316                         ret = err;
317         }
318         return ret;
319 }
320 
321 /**
322  * nilfs_add_checksums_on_logs - add checksums on the logs
323  * @logs: list of segment buffers storing target logs
324  * @seed: checksum seed value
325  */
326 void nilfs_add_checksums_on_logs(struct list_head *logs, u32 seed)
327 {
328         struct nilfs_segment_buffer *segbuf;
329 
330         list_for_each_entry(segbuf, logs, sb_list) {
331                 if (segbuf->sb_super_root)
332                         nilfs_segbuf_fill_in_super_root_crc(segbuf, seed);
333                 nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
334                 nilfs_segbuf_fill_in_data_crc(segbuf, seed);
335         }
336 }
337 
338 /*
339  * BIO operations
340  */
341 static void nilfs_end_bio_write(struct bio *bio, int err)
342 {
343         const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
344         struct nilfs_segment_buffer *segbuf = bio->bi_private;
345 
346         if (!uptodate)
347                 atomic_inc(&segbuf->sb_err);
348 
349         bio_put(bio);
350         complete(&segbuf->sb_bio_event);
351 }
352 
353 static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
354                                    struct nilfs_write_info *wi, int mode)
355 {
356         struct bio *bio = wi->bio;
357         int err;
358 
359         if (segbuf->sb_nbio > 0 &&
360             bdi_write_congested(segbuf->sb_super->s_bdi)) {
361                 wait_for_completion(&segbuf->sb_bio_event);
362                 segbuf->sb_nbio--;
363                 if (unlikely(atomic_read(&segbuf->sb_err))) {
364                         bio_put(bio);
365                         err = -EIO;
366                         goto failed;
367                 }
368         }
369 
370         bio->bi_end_io = nilfs_end_bio_write;
371         bio->bi_private = segbuf;
372         submit_bio(mode, bio);
373         segbuf->sb_nbio++;
374 
375         wi->bio = NULL;
376         wi->rest_blocks -= wi->end - wi->start;
377         wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
378         wi->start = wi->end;
379         return 0;
380 
381  failed:
382         wi->bio = NULL;
383         return err;
384 }
385 
386 /**
387  * nilfs_alloc_seg_bio - allocate a new bio for writing log
388  * @nilfs: nilfs object
389  * @start: start block number of the bio
390  * @nr_vecs: request size of page vector.
391  *
392  * Return Value: On success, pointer to the struct bio is returned.
393  * On error, NULL is returned.
394  */
395 static struct bio *nilfs_alloc_seg_bio(struct the_nilfs *nilfs, sector_t start,
396                                        int nr_vecs)
397 {
398         struct bio *bio;
399 
400         bio = bio_alloc(GFP_NOIO, nr_vecs);
401         if (bio == NULL) {
402                 while (!bio && (nr_vecs >>= 1))
403                         bio = bio_alloc(GFP_NOIO, nr_vecs);
404         }
405         if (likely(bio)) {
406                 bio->bi_bdev = nilfs->ns_bdev;
407                 bio->bi_iter.bi_sector =
408                         start << (nilfs->ns_blocksize_bits - 9);
409         }
410         return bio;
411 }
412 
413 static void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
414                                        struct nilfs_write_info *wi)
415 {
416         wi->bio = NULL;
417         wi->rest_blocks = segbuf->sb_sum.nblocks;
418         wi->max_pages = bio_get_nr_vecs(wi->nilfs->ns_bdev);
419         wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
420         wi->start = wi->end = 0;
421         wi->blocknr = segbuf->sb_pseg_start;
422 }
423 
424 static int nilfs_segbuf_submit_bh(struct nilfs_segment_buffer *segbuf,
425                                   struct nilfs_write_info *wi,
426                                   struct buffer_head *bh, int mode)
427 {
428         int len, err;
429 
430         BUG_ON(wi->nr_vecs <= 0);
431  repeat:
432         if (!wi->bio) {
433                 wi->bio = nilfs_alloc_seg_bio(wi->nilfs, wi->blocknr + wi->end,
434                                               wi->nr_vecs);
435                 if (unlikely(!wi->bio))
436                         return -ENOMEM;
437         }
438 
439         len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
440         if (len == bh->b_size) {
441                 wi->end++;
442                 return 0;
443         }
444         /* bio is FULL */
445         err = nilfs_segbuf_submit_bio(segbuf, wi, mode);
446         /* never submit current bh */
447         if (likely(!err))
448                 goto repeat;
449         return err;
450 }
451 
452 /**
453  * nilfs_segbuf_write - submit write requests of a log
454  * @segbuf: buffer storing a log to be written
455  * @nilfs: nilfs object
456  *
457  * Return Value: On Success, 0 is returned. On Error, one of the following
458  * negative error code is returned.
459  *
460  * %-EIO - I/O error
461  *
462  * %-ENOMEM - Insufficient memory available.
463  */
464 static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
465                               struct the_nilfs *nilfs)
466 {
467         struct nilfs_write_info wi;
468         struct buffer_head *bh;
469         int res = 0, rw = WRITE;
470 
471         wi.nilfs = nilfs;
472         nilfs_segbuf_prepare_write(segbuf, &wi);
473 
474         list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
475                 res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, rw);
476                 if (unlikely(res))
477                         goto failed_bio;
478         }
479 
480         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
481                 res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, rw);
482                 if (unlikely(res))
483                         goto failed_bio;
484         }
485 
486         if (wi.bio) {
487                 /*
488                  * Last BIO is always sent through the following
489                  * submission.
490                  */
491                 rw |= REQ_SYNC;
492                 res = nilfs_segbuf_submit_bio(segbuf, &wi, rw);
493         }
494 
495  failed_bio:
496         return res;
497 }
498 
499 /**
500  * nilfs_segbuf_wait - wait for completion of requested BIOs
501  * @segbuf: segment buffer
502  *
503  * Return Value: On Success, 0 is returned. On Error, one of the following
504  * negative error code is returned.
505  *
506  * %-EIO - I/O error
507  */
508 static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf)
509 {
510         int err = 0;
511 
512         if (!segbuf->sb_nbio)
513                 return 0;
514 
515         do {
516                 wait_for_completion(&segbuf->sb_bio_event);
517         } while (--segbuf->sb_nbio > 0);
518 
519         if (unlikely(atomic_read(&segbuf->sb_err) > 0)) {
520                 printk(KERN_ERR "NILFS: IO error writing segment\n");
521                 err = -EIO;
522         }
523         return err;
524 }
525 

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