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 "page.h"
  29 #include "segbuf.h"
  30
  31
  32 struct nilfs_write_info {
  33         struct the_nilfs       *nilfs;
  34         struct bio             *bio;
  35         int                     start, end; /* The region to be submitted */
  36         int                     rest_blocks;
  37         int                     max_pages;
  38         int                     nr_vecs;
  39         sector_t                blocknr;
  40 };
  41
  42
  43 static struct kmem_cache *nilfs_segbuf_cachep;
  44
  45 static void nilfs_segbuf_init_once(void *obj)
  46 {
  47         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
  48 }
  49
  50 int __init nilfs_init_segbuf_cache(void)
  51 {
  52         nilfs_segbuf_cachep =
  53                 kmem_cache_create("nilfs2_segbuf_cache",
  54                                   sizeof(struct nilfs_segment_buffer),
  55                                   0, SLAB_RECLAIM_ACCOUNT,
  56                                   nilfs_segbuf_init_once);
  57
  58         return (nilfs_segbuf_cachep == NULL) ? -ENOMEM : 0;
  59 }
  60
  61 void nilfs_destroy_segbuf_cache(void)
  62 {
  63         kmem_cache_destroy(nilfs_segbuf_cachep);
  64 }
  65
  66 struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
  67 {
  68         struct nilfs_segment_buffer *segbuf;
  69
  70         segbuf = kmem_cache_alloc(nilfs_segbuf_cachep, GFP_NOFS);
  71         if (unlikely(!segbuf))
  72                 return NULL;
  73
  74         segbuf->sb_super = sb;
  75         INIT_LIST_HEAD(&segbuf->sb_list);
  76         INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
  77         INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
  78
  79         init_completion(&segbuf->sb_bio_event);
  80         atomic_set(&segbuf->sb_err, 0);
  81         segbuf->sb_nbio = 0;
  82
  83         return segbuf;
  84 }
  85
  86 void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
  87 {
  88         kmem_cache_free(nilfs_segbuf_cachep, segbuf);
  89 }
  90
  91 void nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
  92                      unsigned long offset, struct the_nilfs *nilfs)
  93 {
  94         segbuf->sb_segnum = segnum;
  95         nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
  96                                 &segbuf->sb_fseg_end);
  97
  98         segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
  99         segbuf->sb_rest_blocks =
 100                 segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
 101 }
 102
 103 void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
 104                                   __u64 nextnum, struct the_nilfs *nilfs)
 105 {
 106         segbuf->sb_nextnum = nextnum;
 107         segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
 108 }
 109
 110 int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
 111 {
 112         struct buffer_head *bh;
 113
 114         bh = sb_getblk(segbuf->sb_super,
 115                        segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
 116         if (unlikely(!bh))
 117                 return -ENOMEM;
 118
 119         nilfs_segbuf_add_segsum_buffer(segbuf, bh);
 120         return 0;
 121 }
 122
 123 int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
 124                                 struct buffer_head **bhp)
 125 {
 126         struct buffer_head *bh;
 127
 128         bh = sb_getblk(segbuf->sb_super,
 129                        segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
 130         if (unlikely(!bh))
 131                 return -ENOMEM;
 132
 133         nilfs_segbuf_add_payload_buffer(segbuf, bh);
 134         *bhp = bh;
 135         return 0;
 136 }
 137
 138 int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
 139                        time_t ctime)
 140 {
 141         int err;
 142
 143         segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
 144         err = nilfs_segbuf_extend_segsum(segbuf);
 145         if (unlikely(err))
 146                 return err;
 147
 148         segbuf->sb_sum.flags = flags;
 149         segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
 150         segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
 151         segbuf->sb_sum.ctime = ctime;
 152         return 0;
 153 }
 154
 155 /*
 156  * Setup segument summary
 157  */
 158 void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
 159 {
 160         struct nilfs_segment_summary *raw_sum;
 161         struct buffer_head *bh_sum;
 162
 163         bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
 164                             struct buffer_head, b_assoc_buffers);
 165         raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;
 166
 167         raw_sum->ss_magic    = cpu_to_le32(NILFS_SEGSUM_MAGIC);
 168         raw_sum->ss_bytes    = cpu_to_le16(sizeof(*raw_sum));
 169         raw_sum->ss_flags    = cpu_to_le16(segbuf->sb_sum.flags);
 170         raw_sum->ss_seq      = cpu_to_le64(segbuf->sb_sum.seg_seq);
 171         raw_sum->ss_create   = cpu_to_le64(segbuf->sb_sum.ctime);
 172         raw_sum->ss_next     = cpu_to_le64(segbuf->sb_sum.next);
 173         raw_sum->ss_nblocks  = cpu_to_le32(segbuf->sb_sum.nblocks);
 174         raw_sum->ss_nfinfo   = cpu_to_le32(segbuf->sb_sum.nfinfo);
 175         raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
 176         raw_sum->ss_pad      = 0;
 177 }
 178
 179 /*
 180  * CRC calculation routines
 181  */
 182 void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
 183                                      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 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 void nilfs_release_buffers(struct list_head *list)
 238 {
 239         struct buffer_head *bh, *n;
 240
 241         list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
 242                 list_del_init(&bh->b_assoc_buffers);
 243                 if (buffer_nilfs_allocated(bh)) {
 244                         struct page *clone_page = bh->b_page;
 245
 246                         /* remove clone page */
 247                         brelse(bh);
 248                         page_cache_release(clone_page); /* for each bh */
 249                         if (page_count(clone_page) <= 2) {
 250                                 lock_page(clone_page);
 251                                 nilfs_free_private_page(clone_page);
 252                         }
 253                         continue;
 254                 }
 255                 brelse(bh);
 256         }
 257 }
 258
 259 /*
 260  * BIO operations
 261  */
 262 static void nilfs_end_bio_write(struct bio *bio, int err)
 263 {
 264         const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 265         struct nilfs_segment_buffer *segbuf = bio->bi_private;
 266
 267         if (err == -EOPNOTSUPP) {
 268                 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
 269                 bio_put(bio);
 270                 /* to be detected by submit_seg_bio() */
 271         }
 272
 273         if (!uptodate)
 274                 atomic_inc(&segbuf->sb_err);
 275
 276         bio_put(bio);
 277         complete(&segbuf->sb_bio_event);
 278 }
 279
 280 static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
 281                                    struct nilfs_write_info *wi, int mode)
 282 {
 283         struct bio *bio = wi->bio;
 284         int err;
 285
 286         if (segbuf->sb_nbio > 0 && bdi_write_congested(wi->nilfs->ns_bdi)) {
 287                 wait_for_completion(&segbuf->sb_bio_event);
 288                 segbuf->sb_nbio--;
 289                 if (unlikely(atomic_read(&segbuf->sb_err))) {
 290                         bio_put(bio);
 291                         err = -EIO;
 292                         goto failed;
 293                 }
 294         }
 295
 296         bio->bi_end_io = nilfs_end_bio_write;
 297         bio->bi_private = segbuf;
 298         bio_get(bio);
 299         submit_bio(mode, bio);
 300         if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
 301                 bio_put(bio);
 302                 err = -EOPNOTSUPP;
 303                 goto failed;
 304         }
 305         segbuf->sb_nbio++;
 306         bio_put(bio);
 307
 308         wi->bio = NULL;
 309         wi->rest_blocks -= wi->end - wi->start;
 310         wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 311         wi->start = wi->end;
 312         return 0;
 313
 314  failed:
 315         wi->bio = NULL;
 316         return err;
 317 }
 318
 319 /**
 320  * nilfs_alloc_seg_bio - allocate a new bio for writing log
 321  * @nilfs: nilfs object
 322  * @start: start block number of the bio
 323  * @nr_vecs: request size of page vector.
 324  *
 325  * Return Value: On success, pointer to the struct bio is returned.
 326  * On error, NULL is returned.
 327  */
 328 static struct bio *nilfs_alloc_seg_bio(struct the_nilfs *nilfs, sector_t start,
 329                                        int nr_vecs)
 330 {
 331         struct bio *bio;
 332
 333         bio = bio_alloc(GFP_NOIO, nr_vecs);
 334         if (bio == NULL) {
 335                 while (!bio && (nr_vecs >>= 1))
 336                         bio = bio_alloc(GFP_NOIO, nr_vecs);
 337         }
 338         if (likely(bio)) {
 339                 bio->bi_bdev = nilfs->ns_bdev;
 340                 bio->bi_sector = start << (nilfs->ns_blocksize_bits - 9);
 341         }
 342         return bio;
 343 }
 344
 345 static void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
 346                                        struct nilfs_write_info *wi)
 347 {
 348         wi->bio = NULL;
 349         wi->rest_blocks = segbuf->sb_sum.nblocks;
 350         wi->max_pages = bio_get_nr_vecs(wi->nilfs->ns_bdev);
 351         wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 352         wi->start = wi->end = 0;
 353         wi->blocknr = segbuf->sb_pseg_start;
 354 }
 355
 356 static int nilfs_segbuf_submit_bh(struct nilfs_segment_buffer *segbuf,
 357                                   struct nilfs_write_info *wi,
 358                                   struct buffer_head *bh, int mode)
 359 {
 360         int len, err;
 361
 362         BUG_ON(wi->nr_vecs <= 0);
 363  repeat:
 364         if (!wi->bio) {
 365                 wi->bio = nilfs_alloc_seg_bio(wi->nilfs, wi->blocknr + wi->end,
 366                                               wi->nr_vecs);
 367                 if (unlikely(!wi->bio))
 368                         return -ENOMEM;
 369         }
 370
 371         len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
 372         if (len == bh->b_size) {
 373                 wi->end++;
 374                 return 0;
 375         }
 376         /* bio is FULL */
 377         err = nilfs_segbuf_submit_bio(segbuf, wi, mode);
 378         /* never submit current bh */
 379         if (likely(!err))
 380                 goto repeat;
 381         return err;
 382 }
 383
 384 /**
 385  * nilfs_segbuf_write - submit write requests of a log
 386  * @segbuf: buffer storing a log to be written
 387  * @nilfs: nilfs object
 388  *
 389  * Return Value: On Success, 0 is returned. On Error, one of the following
 390  * negative error code is returned.
 391  *
 392  * %-EIO - I/O error
 393  *
 394  * %-ENOMEM - Insufficient memory available.
 395  */
 396 int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
 397                        struct the_nilfs *nilfs)
 398 {
 399         struct nilfs_write_info wi;
 400         struct buffer_head *bh;
 401         int res = 0, rw = WRITE;
 402
 403         wi.nilfs = nilfs;
 404         nilfs_segbuf_prepare_write(segbuf, &wi);
 405
 406         list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
 407                 res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, rw);
 408                 if (unlikely(res))
 409                         goto failed_bio;
 410         }
 411
 412         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
 413                 res = nilfs_segbuf_submit_bh(segbuf, &wi, bh, rw);
 414                 if (unlikely(res))
 415                         goto failed_bio;
 416         }
 417
 418         if (wi.bio) {
 419                 /*
 420                  * Last BIO is always sent through the following
 421                  * submission.
 422                  */
 423                 rw |= (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);
 424                 res = nilfs_segbuf_submit_bio(segbuf, &wi, rw);
 425         }
 426
 427  failed_bio:
 428         return res;
 429 }
 430
 431 /**
 432  * nilfs_segbuf_wait - wait for completion of requested BIOs
 433  * @segbuf: segment buffer
 434  *
 435  * Return Value: On Success, 0 is returned. On Error, one of the following
 436  * negative error code is returned.
 437  *
 438  * %-EIO - I/O error
 439  */
 440 int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf)
 441 {
 442         int err = 0;
 443
 444         if (!segbuf->sb_nbio)
 445                 return 0;
 446
 447         do {
 448                 wait_for_completion(&segbuf->sb_bio_event);
 449         } while (--segbuf->sb_nbio > 0);
 450
 451         if (unlikely(atomic_read(&segbuf->sb_err) > 0)) {
 452                 printk(KERN_ERR "NILFS: IO error writing segment\n");
 453                 err = -EIO;
 454         }
 455         return err;
 456 }