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
  33struct 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
  43static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
  44                              struct the_nilfs *nilfs);
  45static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf);
  46
  47struct 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
  68void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
  69{
  70        kmem_cache_free(nilfs_segbuf_cachep, segbuf);
  71}
  72
  73void 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 */
  90void 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
 101void 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
 108int 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
 121int 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
 136int 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 */
 157void 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 */
 182static void
 183nilfs_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
 210static 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
 237static void
 238nilfs_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
 254static 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
 264static 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 */
 274void 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
 282void 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
 295int 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
 308int 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 */
 326void 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 */
 341static 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 (err == -EOPNOTSUPP) {
 347                set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
 348                /* to be detected by nilfs_segbuf_submit_bio() */
 349        }
 350
 351        if (!uptodate)
 352                atomic_inc(&segbuf->sb_err);
 353
 354        bio_put(bio);
 355        complete(&segbuf->sb_bio_event);
 356}
 357
 358static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
 359                                   struct nilfs_write_info *wi, int mode)
 360{
 361        struct bio *bio = wi->bio;
 362        int err;
 363
 364        if (segbuf->sb_nbio > 0 &&
 365            bdi_write_congested(segbuf->sb_super->s_bdi)) {
 366                wait_for_completion(&segbuf->sb_bio_event);
 367                segbuf->sb_nbio--;
 368                if (unlikely(atomic_read(&segbuf->sb_err))) {
 369                        bio_put(bio);
 370                        err = -EIO;
 371                        goto failed;
 372                }
 373        }
 374
 375        bio->bi_end_io = nilfs_end_bio_write;
 376        bio->bi_private = segbuf;
 377        bio_get(bio);
 378        submit_bio(mode, bio);
 379        segbuf->sb_nbio++;
 380        if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
 381                bio_put(bio);
 382                err = -EOPNOTSUPP;
 383                goto failed;
 384        }
 385        bio_put(bio);
 386
 387        wi->bio = NULL;
 388        wi->rest_blocks -= wi->end - wi->start;
 389        wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 390        wi->start = wi->end;
 391        return 0;
 392
 393 failed:
 394        wi->bio = NULL;
 395        return err;
 396}
 397
 398/**
 399 * nilfs_alloc_seg_bio - allocate a new bio for writing log
 400 * @nilfs: nilfs object
 401 * @start: start block number of the bio
 402 * @nr_vecs: request size of page vector.
 403 *
 404 * Return Value: On success, pointer to the struct bio is returned.
 405 * On error, NULL is returned.
 406 */
 407static struct bio *nilfs_alloc_seg_bio(struct the_nilfs *nilfs, sector_t start,
 408                                       int nr_vecs)
 409{
 410        struct bio *bio;
 411
 412        bio = bio_alloc(GFP_NOIO, nr_vecs);
 413        if (bio == NULL) {
 414                while (!bio && (nr_vecs >>= 1))
 415                        bio = bio_alloc(GFP_NOIO, nr_vecs);
 416        }
 417        if (likely(bio)) {
 418                bio->bi_bdev = nilfs->ns_bdev;
 419                bio->bi_sector = start << (nilfs->ns_blocksize_bits - 9);
 420        }
 421        return bio;
 422}
 423
 424static void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
 425                                       struct nilfs_write_info *wi)
 426{
 427        wi->bio = NULL;
 428        wi->rest_blocks = segbuf->sb_sum.nblocks;
 429        wi->max_pages = bio_get_nr_vecs(wi->nilfs->ns_bdev);
 430        wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 431        wi->start = wi->end = 0;
 432        wi->blocknr = segbuf->sb_pseg_start;
 433}
 434
 435static int nilfs_segbuf_submit_bh(struct nilfs_segment_buffer *segbuf,
 436                                  struct nilfs_write_info *wi,
 437                                  struct buffer_head *bh, int mode)
 438{
 439        int len, err;
 440
 441        BUG_ON(wi->nr_vecs <= 0);
 442 repeat:
 443        if (!wi->bio) {
 444                wi->bio = nilfs_alloc_seg_bio(wi->nilfs, wi->blocknr + wi->end,
 445                                              wi->nr_vecs);
 446                if (unlikely(!wi->bio))
 447                        return -ENOMEM;
 448        }
 449
 450        len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
 451        if (len == bh->b_size) {
 452                wi->end++;
 453                return 0;
 454        }
 455        /* bio is FULL */
 456        err = nilfs_segbuf_submit_bio(segbuf, wi, mode);
 457        /* never submit current bh */
 458        if (likely(!err))
 459                goto repeat;
 460        return err;
 461}
 462
 463/**
 464 * nilfs_segbuf_write - submit write requests of a log
 465 * @segbuf: buffer storing a log to be written
 466 * @nilfs: nilfs object
 467 *
 468 * Return Value: On Success, 0 is returned. On Error, one of the following
 469 * negative error code is returned.
 470 *
 471 * %-EIO - I/O error
 472 *
 473 * %-ENOMEM - Insufficient memory available.
 474 */
 475static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
 476                              struct the_nilfs *nilfs)
 477{
 478        struct nilfs_write_info wi;
 479        struct buffer_head *bh;
 480        int res = 0, rw = WRITE;
 481
 482        wi.nilfs = nilfs;
 483        nilfs_segbuf_prepare_write(segbuf, &wi);
 484
 485        list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
 486                res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, rw);
 487                if (unlikely(res))
 488                        goto failed_bio;
 489        }
 490
 491        list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
 492                res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, rw);
 493                if (unlikely(res))
 494                        goto failed_bio;
 495        }
 496
 497        if (wi.bio) {
 498                /*
 499                 * Last BIO is always sent through the following
 500                 * submission.
 501                 */
 502                rw |= REQ_SYNC;
 503                res = nilfs_segbuf_submit_bio(segbuf, &wi, rw);
 504        }
 505
 506 failed_bio:
 507        return res;
 508}
 509
 510/**
 511 * nilfs_segbuf_wait - wait for completion of requested BIOs
 512 * @segbuf: segment buffer
 513 *
 514 * Return Value: On Success, 0 is returned. On Error, one of the following
 515 * negative error code is returned.
 516 *
 517 * %-EIO - I/O error
 518 */
 519static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf)
 520{
 521        int err = 0;
 522
 523        if (!segbuf->sb_nbio)
 524                return 0;
 525
 526        do {
 527                wait_for_completion(&segbuf->sb_bio_event);
 528        } while (--segbuf->sb_nbio > 0);
 529
 530        if (unlikely(atomic_read(&segbuf->sb_err) > 0)) {
 531                printk(KERN_ERR "NILFS: IO error writing segment\n");
 532                err = -EIO;
 533        }
 534        return err;
 535}
 536
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