release/src-rt-6.x.4708/linux/linux-2.6.36/fs/nilfs2/segbuf.c

   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, KM_USER0);
 231                 crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
 232                 kunmap_atomic(kaddr, KM_USER0);
 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         u32 crc;
 243
 244         raw_sr = (struct nilfs_super_root *)segbuf->sb_super_root->b_data;
 245         crc = crc32_le(seed,
 246                        (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
 247                        NILFS_SR_BYTES - sizeof(raw_sr->sr_sum));
 248         raw_sr->sr_sum = cpu_to_le32(crc);
 249 }
 250
 251 static void nilfs_release_buffers(struct list_head *list)
 252 {
 253         struct buffer_head *bh, *n;
 254
 255         list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
 256                 list_del_init(&bh->b_assoc_buffers);
 257                 if (buffer_nilfs_allocated(bh)) {
 258                         struct page *clone_page = bh->b_page;
 259
 260                         /* remove clone page */
 261                         brelse(bh);
 262                         page_cache_release(clone_page); /* for each bh */
 263                         if (page_count(clone_page) <= 2) {
 264                                 lock_page(clone_page);
 265                                 nilfs_free_private_page(clone_page);
 266                         }
 267                         continue;
 268                 }
 269                 brelse(bh);
 270         }
 271 }
 272
 273 static void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)
 274 {
 275         nilfs_release_buffers(&segbuf->sb_segsum_buffers);
 276         nilfs_release_buffers(&segbuf->sb_payload_buffers);
 277         segbuf->sb_super_root = NULL;
 278 }
 279
 280 /*
 281  * Iterators for segment buffers
 282  */
 283 void nilfs_clear_logs(struct list_head *logs)
 284 {
 285         struct nilfs_segment_buffer *segbuf;
 286
 287         list_for_each_entry(segbuf, logs, sb_list)
 288                 nilfs_segbuf_clear(segbuf);
 289 }
 290
 291 void nilfs_truncate_logs(struct list_head *logs,
 292                          struct nilfs_segment_buffer *last)
 293 {
 294         struct nilfs_segment_buffer *n, *segbuf;
 295
 296         segbuf = list_prepare_entry(last, logs, sb_list);
 297         list_for_each_entry_safe_continue(segbuf, n, logs, sb_list) {
 298                 list_del_init(&segbuf->sb_list);
 299                 nilfs_segbuf_clear(segbuf);
 300                 nilfs_segbuf_free(segbuf);
 301         }
 302 }
 303
 304 int nilfs_write_logs(struct list_head *logs, struct the_nilfs *nilfs)
 305 {
 306         struct nilfs_segment_buffer *segbuf;
 307         int ret = 0;
 308
 309         list_for_each_entry(segbuf, logs, sb_list) {
 310                 ret = nilfs_segbuf_write(segbuf, nilfs);
 311                 if (ret)
 312                         break;
 313         }
 314         return ret;
 315 }
 316
 317 int nilfs_wait_on_logs(struct list_head *logs)
 318 {
 319         struct nilfs_segment_buffer *segbuf;
 320         int err, ret = 0;
 321
 322         list_for_each_entry(segbuf, logs, sb_list) {
 323                 err = nilfs_segbuf_wait(segbuf);
 324                 if (err && !ret)
 325                         ret = err;
 326         }
 327         return ret;
 328 }
 329
 330 /**
 331  * nilfs_add_checksums_on_logs - add checksums on the logs
 332  * @logs: list of segment buffers storing target logs
 333  * @seed: checksum seed value
 334  */
 335 void nilfs_add_checksums_on_logs(struct list_head *logs, u32 seed)
 336 {
 337         struct nilfs_segment_buffer *segbuf;
 338
 339         list_for_each_entry(segbuf, logs, sb_list) {
 340                 if (segbuf->sb_super_root)
 341                         nilfs_segbuf_fill_in_super_root_crc(segbuf, seed);
 342                 nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
 343                 nilfs_segbuf_fill_in_data_crc(segbuf, seed);
 344         }
 345 }
 346
 347 /*
 348  * BIO operations
 349  */
 350 static void nilfs_end_bio_write(struct bio *bio, int err)
 351 {
 352         const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 353         struct nilfs_segment_buffer *segbuf = bio->bi_private;
 354
 355         if (err == -EOPNOTSUPP) {
 356                 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
 357                 bio_put(bio);
 358                 /* to be detected by submit_seg_bio() */
 359         }
 360
 361         if (!uptodate)
 362                 atomic_inc(&segbuf->sb_err);
 363
 364         bio_put(bio);
 365         complete(&segbuf->sb_bio_event);
 366 }
 367
 368 static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
 369                                    struct nilfs_write_info *wi, int mode)
 370 {
 371         struct bio *bio = wi->bio;
 372         int err;
 373
 374         if (segbuf->sb_nbio > 0 && bdi_write_congested(wi->nilfs->ns_bdi)) {
 375                 wait_for_completion(&segbuf->sb_bio_event);
 376                 segbuf->sb_nbio--;
 377                 if (unlikely(atomic_read(&segbuf->sb_err))) {
 378                         bio_put(bio);
 379                         err = -EIO;
 380                         goto failed;
 381                 }
 382         }
 383
 384         bio->bi_end_io = nilfs_end_bio_write;
 385         bio->bi_private = segbuf;
 386         bio_get(bio);
 387         submit_bio(mode, bio);
 388         if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
 389                 bio_put(bio);
 390                 err = -EOPNOTSUPP;
 391                 goto failed;
 392         }
 393         segbuf->sb_nbio++;
 394         bio_put(bio);
 395
 396         wi->bio = NULL;
 397         wi->rest_blocks -= wi->end - wi->start;
 398         wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 399         wi->start = wi->end;
 400         return 0;
 401
 402  failed:
 403         wi->bio = NULL;
 404         return err;
 405 }
 406
 407 /**
 408  * nilfs_alloc_seg_bio - allocate a new bio for writing log
 409  * @nilfs: nilfs object
 410  * @start: start block number of the bio
 411  * @nr_vecs: request size of page vector.
 412  *
 413  * Return Value: On success, pointer to the struct bio is returned.
 414  * On error, NULL is returned.
 415  */
 416 static struct bio *nilfs_alloc_seg_bio(struct the_nilfs *nilfs, sector_t start,
 417                                        int nr_vecs)
 418 {
 419         struct bio *bio;
 420
 421         bio = bio_alloc(GFP_NOIO, nr_vecs);
 422         if (bio == NULL) {
 423                 while (!bio && (nr_vecs >>= 1))
 424                         bio = bio_alloc(GFP_NOIO, nr_vecs);
 425         }
 426         if (likely(bio)) {
 427                 bio->bi_bdev = nilfs->ns_bdev;
 428                 bio->bi_sector = start << (nilfs->ns_blocksize_bits - 9);
 429         }
 430         return bio;
 431 }
 432
 433 static void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
 434                                        struct nilfs_write_info *wi)
 435 {
 436         wi->bio = NULL;
 437         wi->rest_blocks = segbuf->sb_sum.nblocks;
 438         wi->max_pages = bio_get_nr_vecs(wi->nilfs->ns_bdev);
 439         wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 440         wi->start = wi->end = 0;
 441         wi->blocknr = segbuf->sb_pseg_start;
 442 }
 443
 444 static int nilfs_segbuf_submit_bh(struct nilfs_segment_buffer *segbuf,
 445                                   struct nilfs_write_info *wi,
 446                                   struct buffer_head *bh, int mode)
 447 {
 448         int len, err;
 449
 450         BUG_ON(wi->nr_vecs <= 0);
 451  repeat:
 452         if (!wi->bio) {
 453                 wi->bio = nilfs_alloc_seg_bio(wi->nilfs, wi->blocknr + wi->end,
 454                                               wi->nr_vecs);
 455                 if (unlikely(!wi->bio))
 456                         return -ENOMEM;
 457         }
 458
 459         len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
 460         if (len == bh->b_size) {
 461                 wi->end++;
 462                 return 0;
 463         }
 464         /* bio is FULL */
 465         err = nilfs_segbuf_submit_bio(segbuf, wi, mode);
 466         /* never submit current bh */
 467         if (likely(!err))
 468                 goto repeat;
 469         return err;
 470 }
 471
 472 /**
 473  * nilfs_segbuf_write - submit write requests of a log
 474  * @segbuf: buffer storing a log to be written
 475  * @nilfs: nilfs object
 476  *
 477  * Return Value: On Success, 0 is returned. On Error, one of the following
 478  * negative error code is returned.
 479  *
 480  * %-EIO - I/O error
 481  *
 482  * %-ENOMEM - Insufficient memory available.
 483  */
 484 static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
 485                               struct the_nilfs *nilfs)
 486 {
 487         struct nilfs_write_info wi;
 488         struct buffer_head *bh;
 489         int res = 0, rw = WRITE;
 490
 491         wi.nilfs = nilfs;
 492         nilfs_segbuf_prepare_write(segbuf, &wi);
 493
 494         list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
 495                 res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, rw);
 496                 if (unlikely(res))
 497                         goto failed_bio;
 498         }
 499
 500         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
 501                 res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, rw);
 502                 if (unlikely(res))
 503                         goto failed_bio;
 504         }
 505
 506         if (wi.bio) {
 507                 /*
 508                  * Last BIO is always sent through the following
 509                  * submission.
 510                  */
 511                 rw |= REQ_SYNC | REQ_UNPLUG;
 512                 res = nilfs_segbuf_submit_bio(segbuf, &wi, rw);
 513         }
 514
 515  failed_bio:
 516         return res;
 517 }
 518
 519 /**
 520  * nilfs_segbuf_wait - wait for completion of requested BIOs
 521  * @segbuf: segment buffer
 522  *
 523  * Return Value: On Success, 0 is returned. On Error, one of the following
 524  * negative error code is returned.
 525  *
 526  * %-EIO - I/O error
 527  */
 528 static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf)
 529 {
 530         int err = 0;
 531
 532         if (!segbuf->sb_nbio)
 533                 return 0;
 534
 535         do {
 536                 wait_for_completion(&segbuf->sb_bio_event);
 537         } while (--segbuf->sb_nbio > 0);
 538
 539         if (unlikely(atomic_read(&segbuf->sb_err) > 0)) {
 540                 printk(KERN_ERR "NILFS: IO error writing segment\n");
 541                 err = -EIO;
 542         }
 543         return err;
 544 }