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 * Written by Ryusuke Konishi.
  17 *
  18 */
  19
  20#include <linux/buffer_head.h>
  21#include <linux/writeback.h>
  22#include <linux/crc32.h>
  23#include <linux/backing-dev.h>
  24#include <linux/slab.h>
  25#include "page.h"
  26#include "segbuf.h"
  27
  28
  29struct nilfs_write_info {
  30        struct the_nilfs       *nilfs;
  31        struct bio             *bio;
  32        int                     start, end; /* The region to be submitted */
  33        int                     rest_blocks;
  34        int                     max_pages;
  35        int                     nr_vecs;
  36        sector_t                blocknr;
  37};
  38
  39static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
  40                              struct the_nilfs *nilfs);
  41static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf);
  42
  43struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
  44{
  45        struct nilfs_segment_buffer *segbuf;
  46
  47        segbuf = kmem_cache_alloc(nilfs_segbuf_cachep, GFP_NOFS);
  48        if (unlikely(!segbuf))
  49                return NULL;
  50
  51        segbuf->sb_super = sb;
  52        INIT_LIST_HEAD(&segbuf->sb_list);
  53        INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
  54        INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
  55        segbuf->sb_super_root = NULL;
  56
  57        init_completion(&segbuf->sb_bio_event);
  58        atomic_set(&segbuf->sb_err, 0);
  59        segbuf->sb_nbio = 0;
  60
  61        return segbuf;
  62}
  63
  64void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
  65{
  66        kmem_cache_free(nilfs_segbuf_cachep, segbuf);
  67}
  68
  69void nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
  70                     unsigned long offset, struct the_nilfs *nilfs)
  71{
  72        segbuf->sb_segnum = segnum;
  73        nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
  74                                &segbuf->sb_fseg_end);
  75
  76        segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
  77        segbuf->sb_rest_blocks =
  78                segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
  79}
  80
  81/**
  82 * nilfs_segbuf_map_cont - map a new log behind a given log
  83 * @segbuf: new segment buffer
  84 * @prev: segment buffer containing a log to be continued
  85 */
  86void nilfs_segbuf_map_cont(struct nilfs_segment_buffer *segbuf,
  87                           struct nilfs_segment_buffer *prev)
  88{
  89        segbuf->sb_segnum = prev->sb_segnum;
  90        segbuf->sb_fseg_start = prev->sb_fseg_start;
  91        segbuf->sb_fseg_end = prev->sb_fseg_end;
  92        segbuf->sb_pseg_start = prev->sb_pseg_start + prev->sb_sum.nblocks;
  93        segbuf->sb_rest_blocks =
  94                segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
  95}
  96
  97void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
  98                                  __u64 nextnum, struct the_nilfs *nilfs)
  99{
 100        segbuf->sb_nextnum = nextnum;
 101        segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
 102}
 103
 104int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
 105{
 106        struct buffer_head *bh;
 107
 108        bh = sb_getblk(segbuf->sb_super,
 109                       segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
 110        if (unlikely(!bh))
 111                return -ENOMEM;
 112
 113        nilfs_segbuf_add_segsum_buffer(segbuf, bh);
 114        return 0;
 115}
 116
 117int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
 118                                struct buffer_head **bhp)
 119{
 120        struct buffer_head *bh;
 121
 122        bh = sb_getblk(segbuf->sb_super,
 123                       segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
 124        if (unlikely(!bh))
 125                return -ENOMEM;
 126
 127        nilfs_segbuf_add_payload_buffer(segbuf, bh);
 128        *bhp = bh;
 129        return 0;
 130}
 131
 132int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned int flags,
 133                       time_t ctime, __u64 cno)
 134{
 135        int err;
 136
 137        segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
 138        err = nilfs_segbuf_extend_segsum(segbuf);
 139        if (unlikely(err))
 140                return err;
 141
 142        segbuf->sb_sum.flags = flags;
 143        segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
 144        segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
 145        segbuf->sb_sum.ctime = ctime;
 146        segbuf->sb_sum.cno = cno;
 147        return 0;
 148}
 149
 150/*
 151 * Setup segment summary
 152 */
 153void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
 154{
 155        struct nilfs_segment_summary *raw_sum;
 156        struct buffer_head *bh_sum;
 157
 158        bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
 159                            struct buffer_head, b_assoc_buffers);
 160        raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;
 161
 162        raw_sum->ss_magic    = cpu_to_le32(NILFS_SEGSUM_MAGIC);
 163        raw_sum->ss_bytes    = cpu_to_le16(sizeof(*raw_sum));
 164        raw_sum->ss_flags    = cpu_to_le16(segbuf->sb_sum.flags);
 165        raw_sum->ss_seq      = cpu_to_le64(segbuf->sb_sum.seg_seq);
 166        raw_sum->ss_create   = cpu_to_le64(segbuf->sb_sum.ctime);
 167        raw_sum->ss_next     = cpu_to_le64(segbuf->sb_sum.next);
 168        raw_sum->ss_nblocks  = cpu_to_le32(segbuf->sb_sum.nblocks);
 169        raw_sum->ss_nfinfo   = cpu_to_le32(segbuf->sb_sum.nfinfo);
 170        raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
 171        raw_sum->ss_pad      = 0;
 172        raw_sum->ss_cno      = cpu_to_le64(segbuf->sb_sum.cno);
 173}
 174
 175/*
 176 * CRC calculation routines
 177 */
 178static void
 179nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf, u32 seed)
 180{
 181        struct buffer_head *bh;
 182        struct nilfs_segment_summary *raw_sum;
 183        unsigned long size, bytes = segbuf->sb_sum.sumbytes;
 184        u32 crc;
 185
 186        bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
 187                        b_assoc_buffers);
 188
 189        raw_sum = (struct nilfs_segment_summary *)bh->b_data;
 190        size = min_t(unsigned long, bytes, bh->b_size);
 191        crc = crc32_le(seed,
 192                       (unsigned char *)raw_sum +
 193                       sizeof(raw_sum->ss_datasum) + sizeof(raw_sum->ss_sumsum),
 194                       size - (sizeof(raw_sum->ss_datasum) +
 195                               sizeof(raw_sum->ss_sumsum)));
 196
 197        list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
 198                                     b_assoc_buffers) {
 199                bytes -= size;
 200                size = min_t(unsigned long, bytes, bh->b_size);
 201                crc = crc32_le(crc, bh->b_data, size);
 202        }
 203        raw_sum->ss_sumsum = cpu_to_le32(crc);
 204}
 205
 206static void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
 207                                          u32 seed)
 208{
 209        struct buffer_head *bh;
 210        struct nilfs_segment_summary *raw_sum;
 211        void *kaddr;
 212        u32 crc;
 213
 214        bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
 215                        b_assoc_buffers);
 216        raw_sum = (struct nilfs_segment_summary *)bh->b_data;
 217        crc = crc32_le(seed,
 218                       (unsigned char *)raw_sum + sizeof(raw_sum->ss_datasum),
 219                       bh->b_size - sizeof(raw_sum->ss_datasum));
 220
 221        list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
 222                                     b_assoc_buffers) {
 223                crc = crc32_le(crc, bh->b_data, bh->b_size);
 224        }
 225        list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
 226                kaddr = kmap_atomic(bh->b_page);
 227                crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
 228                kunmap_atomic(kaddr);
 229        }
 230        raw_sum->ss_datasum = cpu_to_le32(crc);
 231}
 232
 233static void
 234nilfs_segbuf_fill_in_super_root_crc(struct nilfs_segment_buffer *segbuf,
 235                                    u32 seed)
 236{
 237        struct nilfs_super_root *raw_sr;
 238        struct the_nilfs *nilfs = segbuf->sb_super->s_fs_info;
 239        unsigned int srsize;
 240        u32 crc;
 241
 242        raw_sr = (struct nilfs_super_root *)segbuf->sb_super_root->b_data;
 243        srsize = NILFS_SR_BYTES(nilfs->ns_inode_size);
 244        crc = crc32_le(seed,
 245                       (unsigned char *)raw_sr + sizeof(raw_sr->sr_sum),
 246                       srsize - sizeof(raw_sr->sr_sum));
 247        raw_sr->sr_sum = cpu_to_le32(crc);
 248}
 249
 250static void nilfs_release_buffers(struct list_head *list)
 251{
 252        struct buffer_head *bh, *n;
 253
 254        list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
 255                list_del_init(&bh->b_assoc_buffers);
 256                brelse(bh);
 257        }
 258}
 259
 260static void nilfs_segbuf_clear(struct nilfs_segment_buffer *segbuf)
 261{
 262        nilfs_release_buffers(&segbuf->sb_segsum_buffers);
 263        nilfs_release_buffers(&segbuf->sb_payload_buffers);
 264        segbuf->sb_super_root = NULL;
 265}
 266
 267/*
 268 * Iterators for segment buffers
 269 */
 270void nilfs_clear_logs(struct list_head *logs)
 271{
 272        struct nilfs_segment_buffer *segbuf;
 273
 274        list_for_each_entry(segbuf, logs, sb_list)
 275                nilfs_segbuf_clear(segbuf);
 276}
 277
 278void nilfs_truncate_logs(struct list_head *logs,
 279                         struct nilfs_segment_buffer *last)
 280{
 281        struct nilfs_segment_buffer *n, *segbuf;
 282
 283        segbuf = list_prepare_entry(last, logs, sb_list);
 284        list_for_each_entry_safe_continue(segbuf, n, logs, sb_list) {
 285                list_del_init(&segbuf->sb_list);
 286                nilfs_segbuf_clear(segbuf);
 287                nilfs_segbuf_free(segbuf);
 288        }
 289}
 290
 291int nilfs_write_logs(struct list_head *logs, struct the_nilfs *nilfs)
 292{
 293        struct nilfs_segment_buffer *segbuf;
 294        int ret = 0;
 295
 296        list_for_each_entry(segbuf, logs, sb_list) {
 297                ret = nilfs_segbuf_write(segbuf, nilfs);
 298                if (ret)
 299                        break;
 300        }
 301        return ret;
 302}
 303
 304int nilfs_wait_on_logs(struct list_head *logs)
 305{
 306        struct nilfs_segment_buffer *segbuf;
 307        int err, ret = 0;
 308
 309        list_for_each_entry(segbuf, logs, sb_list) {
 310                err = nilfs_segbuf_wait(segbuf);
 311                if (err && !ret)
 312                        ret = err;
 313        }
 314        return ret;
 315}
 316
 317/**
 318 * nilfs_add_checksums_on_logs - add checksums on the logs
 319 * @logs: list of segment buffers storing target logs
 320 * @seed: checksum seed value
 321 */
 322void nilfs_add_checksums_on_logs(struct list_head *logs, u32 seed)
 323{
 324        struct nilfs_segment_buffer *segbuf;
 325
 326        list_for_each_entry(segbuf, logs, sb_list) {
 327                if (segbuf->sb_super_root)
 328                        nilfs_segbuf_fill_in_super_root_crc(segbuf, seed);
 329                nilfs_segbuf_fill_in_segsum_crc(segbuf, seed);
 330                nilfs_segbuf_fill_in_data_crc(segbuf, seed);
 331        }
 332}
 333
 334/*
 335 * BIO operations
 336 */
 337static void nilfs_end_bio_write(struct bio *bio)
 338{
 339        struct nilfs_segment_buffer *segbuf = bio->bi_private;
 340
 341        if (bio->bi_status)
 342                atomic_inc(&segbuf->sb_err);
 343
 344        bio_put(bio);
 345        complete(&segbuf->sb_bio_event);
 346}
 347
 348static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
 349                                   struct nilfs_write_info *wi, int mode,
 350                                   int mode_flags)
 351{
 352        struct bio *bio = wi->bio;
 353        int err;
 354
 355        if (segbuf->sb_nbio > 0 &&
 356            bdi_write_congested(segbuf->sb_super->s_bdi)) {
 357                wait_for_completion(&segbuf->sb_bio_event);
 358                segbuf->sb_nbio--;
 359                if (unlikely(atomic_read(&segbuf->sb_err))) {
 360                        bio_put(bio);
 361                        err = -EIO;
 362                        goto failed;
 363                }
 364        }
 365
 366        bio->bi_end_io = nilfs_end_bio_write;
 367        bio->bi_private = segbuf;
 368        bio_set_op_attrs(bio, mode, mode_flags);
 369        submit_bio(bio);
 370        segbuf->sb_nbio++;
 371
 372        wi->bio = NULL;
 373        wi->rest_blocks -= wi->end - wi->start;
 374        wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 375        wi->start = wi->end;
 376        return 0;
 377
 378 failed:
 379        wi->bio = NULL;
 380        return err;
 381}
 382
 383/**
 384 * nilfs_alloc_seg_bio - allocate a new bio for writing log
 385 * @nilfs: nilfs object
 386 * @start: start block number of the bio
 387 * @nr_vecs: request size of page vector.
 388 *
 389 * Return Value: On success, pointer to the struct bio is returned.
 390 * On error, NULL is returned.
 391 */
 392static struct bio *nilfs_alloc_seg_bio(struct the_nilfs *nilfs, sector_t start,
 393                                       int nr_vecs)
 394{
 395        struct bio *bio;
 396
 397        bio = bio_alloc(GFP_NOIO, nr_vecs);
 398        if (bio == NULL) {
 399                while (!bio && (nr_vecs >>= 1))
 400                        bio = bio_alloc(GFP_NOIO, nr_vecs);
 401        }
 402        if (likely(bio)) {
 403                bio_set_dev(bio, nilfs->ns_bdev);
 404                bio->bi_iter.bi_sector =
 405                        start << (nilfs->ns_blocksize_bits - 9);
 406        }
 407        return bio;
 408}
 409
 410static void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
 411                                       struct nilfs_write_info *wi)
 412{
 413        wi->bio = NULL;
 414        wi->rest_blocks = segbuf->sb_sum.nblocks;
 415        wi->max_pages = BIO_MAX_PAGES;
 416        wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 417        wi->start = wi->end = 0;
 418        wi->blocknr = segbuf->sb_pseg_start;
 419}
 420
 421static int nilfs_segbuf_submit_bh(struct nilfs_segment_buffer *segbuf,
 422                                  struct nilfs_write_info *wi,
 423                                  struct buffer_head *bh, int mode)
 424{
 425        int len, err;
 426
 427        BUG_ON(wi->nr_vecs <= 0);
 428 repeat:
 429        if (!wi->bio) {
 430                wi->bio = nilfs_alloc_seg_bio(wi->nilfs, wi->blocknr + wi->end,
 431                                              wi->nr_vecs);
 432                if (unlikely(!wi->bio))
 433                        return -ENOMEM;
 434        }
 435
 436        len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
 437        if (len == bh->b_size) {
 438                wi->end++;
 439                return 0;
 440        }
 441        /* bio is FULL */
 442        err = nilfs_segbuf_submit_bio(segbuf, wi, mode, 0);
 443        /* never submit current bh */
 444        if (likely(!err))
 445                goto repeat;
 446        return err;
 447}
 448
 449/**
 450 * nilfs_segbuf_write - submit write requests of a log
 451 * @segbuf: buffer storing a log to be written
 452 * @nilfs: nilfs object
 453 *
 454 * Return Value: On Success, 0 is returned. On Error, one of the following
 455 * negative error code is returned.
 456 *
 457 * %-EIO - I/O error
 458 *
 459 * %-ENOMEM - Insufficient memory available.
 460 */
 461static int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
 462                              struct the_nilfs *nilfs)
 463{
 464        struct nilfs_write_info wi;
 465        struct buffer_head *bh;
 466        int res = 0;
 467
 468        wi.nilfs = nilfs;
 469        nilfs_segbuf_prepare_write(segbuf, &wi);
 470
 471        list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
 472                res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, REQ_OP_WRITE);
 473                if (unlikely(res))
 474                        goto failed_bio;
 475        }
 476
 477        list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
 478                res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, REQ_OP_WRITE);
 479                if (unlikely(res))
 480                        goto failed_bio;
 481        }
 482
 483        if (wi.bio) {
 484                /*
 485                 * Last BIO is always sent through the following
 486                 * submission.
 487                 */
 488                res = nilfs_segbuf_submit_bio(segbuf, &wi, REQ_OP_WRITE,
 489                                              REQ_SYNC);
 490        }
 491
 492 failed_bio:
 493        return res;
 494}
 495
 496/**
 497 * nilfs_segbuf_wait - wait for completion of requested BIOs
 498 * @segbuf: segment buffer
 499 *
 500 * Return Value: On Success, 0 is returned. On Error, one of the following
 501 * negative error code is returned.
 502 *
 503 * %-EIO - I/O error
 504 */
 505static int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf)
 506{
 507        int err = 0;
 508
 509        if (!segbuf->sb_nbio)
 510                return 0;
 511
 512        do {
 513                wait_for_completion(&segbuf->sb_bio_event);
 514        } while (--segbuf->sb_nbio > 0);
 515
 516        if (unlikely(atomic_read(&segbuf->sb_err) > 0)) {
 517                nilfs_msg(segbuf->sb_super, KERN_ERR,
 518                          "I/O error writing log (start-blocknr=%llu, block-count=%lu) in segment %llu",
 519                          (unsigned long long)segbuf->sb_pseg_start,
 520                          segbuf->sb_sum.nblocks,
 521                          (unsigned long long)segbuf->sb_segnum);
 522                err = -EIO;
 523        }
 524        return err;
 525}
 526