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 "page.h"
  28 #include "segbuf.h"
  29
  30
  31 static struct kmem_cache *nilfs_segbuf_cachep;
  32
  33 static void nilfs_segbuf_init_once(void *obj)
  34 {
  35         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
  36 }
  37
  38 int __init nilfs_init_segbuf_cache(void)
  39 {
  40         nilfs_segbuf_cachep =
  41                 kmem_cache_create("nilfs2_segbuf_cache",
  42                                   sizeof(struct nilfs_segment_buffer),
  43                                   0, SLAB_RECLAIM_ACCOUNT,
  44                                   nilfs_segbuf_init_once);
  45
  46         return (nilfs_segbuf_cachep == NULL) ? -ENOMEM : 0;
  47 }
  48
  49 void nilfs_destroy_segbuf_cache(void)
  50 {
  51         kmem_cache_destroy(nilfs_segbuf_cachep);
  52 }
  53
  54 struct nilfs_segment_buffer *nilfs_segbuf_new(struct super_block *sb)
  55 {
  56         struct nilfs_segment_buffer *segbuf;
  57
  58         segbuf = kmem_cache_alloc(nilfs_segbuf_cachep, GFP_NOFS);
  59         if (unlikely(!segbuf))
  60                 return NULL;
  61
  62         segbuf->sb_super = sb;
  63         INIT_LIST_HEAD(&segbuf->sb_list);
  64         INIT_LIST_HEAD(&segbuf->sb_segsum_buffers);
  65         INIT_LIST_HEAD(&segbuf->sb_payload_buffers);
  66         return segbuf;
  67 }
  68
  69 void nilfs_segbuf_free(struct nilfs_segment_buffer *segbuf)
  70 {
  71         kmem_cache_free(nilfs_segbuf_cachep, segbuf);
  72 }
  73
  74 void nilfs_segbuf_map(struct nilfs_segment_buffer *segbuf, __u64 segnum,
  75                      unsigned long offset, struct the_nilfs *nilfs)
  76 {
  77         segbuf->sb_segnum = segnum;
  78         nilfs_get_segment_range(nilfs, segnum, &segbuf->sb_fseg_start,
  79                                 &segbuf->sb_fseg_end);
  80
  81         segbuf->sb_pseg_start = segbuf->sb_fseg_start + offset;
  82         segbuf->sb_rest_blocks =
  83                 segbuf->sb_fseg_end - segbuf->sb_pseg_start + 1;
  84 }
  85
  86 void nilfs_segbuf_set_next_segnum(struct nilfs_segment_buffer *segbuf,
  87                                   __u64 nextnum, struct the_nilfs *nilfs)
  88 {
  89         segbuf->sb_nextnum = nextnum;
  90         segbuf->sb_sum.next = nilfs_get_segment_start_blocknr(nilfs, nextnum);
  91 }
  92
  93 int nilfs_segbuf_extend_segsum(struct nilfs_segment_buffer *segbuf)
  94 {
  95         struct buffer_head *bh;
  96
  97         bh = sb_getblk(segbuf->sb_super,
  98                        segbuf->sb_pseg_start + segbuf->sb_sum.nsumblk);
  99         if (unlikely(!bh))
 100                 return -ENOMEM;
 101
 102         nilfs_segbuf_add_segsum_buffer(segbuf, bh);
 103         return 0;
 104 }
 105
 106 int nilfs_segbuf_extend_payload(struct nilfs_segment_buffer *segbuf,
 107                                 struct buffer_head **bhp)
 108 {
 109         struct buffer_head *bh;
 110
 111         bh = sb_getblk(segbuf->sb_super,
 112                        segbuf->sb_pseg_start + segbuf->sb_sum.nblocks);
 113         if (unlikely(!bh))
 114                 return -ENOMEM;
 115
 116         nilfs_segbuf_add_payload_buffer(segbuf, bh);
 117         *bhp = bh;
 118         return 0;
 119 }
 120
 121 int nilfs_segbuf_reset(struct nilfs_segment_buffer *segbuf, unsigned flags,
 122                        time_t ctime)
 123 {
 124         int err;
 125
 126         segbuf->sb_sum.nblocks = segbuf->sb_sum.nsumblk = 0;
 127         err = nilfs_segbuf_extend_segsum(segbuf);
 128         if (unlikely(err))
 129                 return err;
 130
 131         segbuf->sb_sum.flags = flags;
 132         segbuf->sb_sum.sumbytes = sizeof(struct nilfs_segment_summary);
 133         segbuf->sb_sum.nfinfo = segbuf->sb_sum.nfileblk = 0;
 134         segbuf->sb_sum.ctime = ctime;
 135
 136         segbuf->sb_io_error = 0;
 137         return 0;
 138 }
 139
 140 /*
 141  * Setup segument summary
 142  */
 143 void nilfs_segbuf_fill_in_segsum(struct nilfs_segment_buffer *segbuf)
 144 {
 145         struct nilfs_segment_summary *raw_sum;
 146         struct buffer_head *bh_sum;
 147
 148         bh_sum = list_entry(segbuf->sb_segsum_buffers.next,
 149                             struct buffer_head, b_assoc_buffers);
 150         raw_sum = (struct nilfs_segment_summary *)bh_sum->b_data;
 151
 152         raw_sum->ss_magic    = cpu_to_le32(NILFS_SEGSUM_MAGIC);
 153         raw_sum->ss_bytes    = cpu_to_le16(sizeof(*raw_sum));
 154         raw_sum->ss_flags    = cpu_to_le16(segbuf->sb_sum.flags);
 155         raw_sum->ss_seq      = cpu_to_le64(segbuf->sb_sum.seg_seq);
 156         raw_sum->ss_create   = cpu_to_le64(segbuf->sb_sum.ctime);
 157         raw_sum->ss_next     = cpu_to_le64(segbuf->sb_sum.next);
 158         raw_sum->ss_nblocks  = cpu_to_le32(segbuf->sb_sum.nblocks);
 159         raw_sum->ss_nfinfo   = cpu_to_le32(segbuf->sb_sum.nfinfo);
 160         raw_sum->ss_sumbytes = cpu_to_le32(segbuf->sb_sum.sumbytes);
 161         raw_sum->ss_pad      = 0;
 162 }
 163
 164 /*
 165  * CRC calculation routines
 166  */
 167 void nilfs_segbuf_fill_in_segsum_crc(struct nilfs_segment_buffer *segbuf,
 168                                      u32 seed)
 169 {
 170         struct buffer_head *bh;
 171         struct nilfs_segment_summary *raw_sum;
 172         unsigned long size, bytes = segbuf->sb_sum.sumbytes;
 173         u32 crc;
 174
 175         bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
 176                         b_assoc_buffers);
 177
 178         raw_sum = (struct nilfs_segment_summary *)bh->b_data;
 179         size = min_t(unsigned long, bytes, bh->b_size);
 180         crc = crc32_le(seed,
 181                        (unsigned char *)raw_sum +
 182                        sizeof(raw_sum->ss_datasum) + sizeof(raw_sum->ss_sumsum),
 183                        size - (sizeof(raw_sum->ss_datasum) +
 184                                sizeof(raw_sum->ss_sumsum)));
 185
 186         list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
 187                                      b_assoc_buffers) {
 188                 bytes -= size;
 189                 size = min_t(unsigned long, bytes, bh->b_size);
 190                 crc = crc32_le(crc, bh->b_data, size);
 191         }
 192         raw_sum->ss_sumsum = cpu_to_le32(crc);
 193 }
 194
 195 void nilfs_segbuf_fill_in_data_crc(struct nilfs_segment_buffer *segbuf,
 196                                    u32 seed)
 197 {
 198         struct buffer_head *bh;
 199         struct nilfs_segment_summary *raw_sum;
 200         void *kaddr;
 201         u32 crc;
 202
 203         bh = list_entry(segbuf->sb_segsum_buffers.next, struct buffer_head,
 204                         b_assoc_buffers);
 205         raw_sum = (struct nilfs_segment_summary *)bh->b_data;
 206         crc = crc32_le(seed,
 207                        (unsigned char *)raw_sum + sizeof(raw_sum->ss_datasum),
 208                        bh->b_size - sizeof(raw_sum->ss_datasum));
 209
 210         list_for_each_entry_continue(bh, &segbuf->sb_segsum_buffers,
 211                                      b_assoc_buffers) {
 212                 crc = crc32_le(crc, bh->b_data, bh->b_size);
 213         }
 214         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
 215                 kaddr = kmap_atomic(bh->b_page, KM_USER0);
 216                 crc = crc32_le(crc, kaddr + bh_offset(bh), bh->b_size);
 217                 kunmap_atomic(kaddr, KM_USER0);
 218         }
 219         raw_sum->ss_datasum = cpu_to_le32(crc);
 220 }
 221
 222 void nilfs_release_buffers(struct list_head *list)
 223 {
 224         struct buffer_head *bh, *n;
 225
 226         list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
 227                 list_del_init(&bh->b_assoc_buffers);
 228                 if (buffer_nilfs_allocated(bh)) {
 229                         struct page *clone_page = bh->b_page;
 230
 231                         /* remove clone page */
 232                         brelse(bh);
 233                         page_cache_release(clone_page); /* for each bh */
 234                         if (page_count(clone_page) <= 2) {
 235                                 lock_page(clone_page);
 236                                 nilfs_free_private_page(clone_page);
 237                         }
 238                         continue;
 239                 }
 240                 brelse(bh);
 241         }
 242 }
 243
 244 /*
 245  * BIO operations
 246  */
 247 static void nilfs_end_bio_write(struct bio *bio, int err)
 248 {
 249         const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
 250         struct nilfs_write_info *wi = bio->bi_private;
 251
 252         if (err == -EOPNOTSUPP) {
 253                 set_bit(BIO_EOPNOTSUPP, &bio->bi_flags);
 254                 bio_put(bio);
 255                 /* to be detected by submit_seg_bio() */
 256         }
 257
 258         if (!uptodate)
 259                 atomic_inc(&wi->err);
 260
 261         bio_put(bio);
 262         complete(&wi->bio_event);
 263 }
 264
 265 static int nilfs_submit_seg_bio(struct nilfs_write_info *wi, int mode)
 266 {
 267         struct bio *bio = wi->bio;
 268         int err;
 269
 270         if (wi->nbio > 0 && bdi_write_congested(wi->bdi)) {
 271                 wait_for_completion(&wi->bio_event);
 272                 wi->nbio--;
 273                 if (unlikely(atomic_read(&wi->err))) {
 274                         bio_put(bio);
 275                         err = -EIO;
 276                         goto failed;
 277                 }
 278         }
 279
 280         bio->bi_end_io = nilfs_end_bio_write;
 281         bio->bi_private = wi;
 282         bio_get(bio);
 283         submit_bio(mode, bio);
 284         if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
 285                 bio_put(bio);
 286                 err = -EOPNOTSUPP;
 287                 goto failed;
 288         }
 289         wi->nbio++;
 290         bio_put(bio);
 291
 292         wi->bio = NULL;
 293         wi->rest_blocks -= wi->end - wi->start;
 294         wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 295         wi->start = wi->end;
 296         return 0;
 297
 298  failed:
 299         wi->bio = NULL;
 300         return err;
 301 }
 302
 303 /**
 304  * nilfs_alloc_seg_bio - allocate a bio for writing segment.
 305  * @sb: super block
 306  * @start: beginning disk block number of this BIO.
 307  * @nr_vecs: request size of page vector.
 308  *
 309  * alloc_seg_bio() allocates a new BIO structure and initialize it.
 310  *
 311  * Return Value: On success, pointer to the struct bio is returned.
 312  * On error, NULL is returned.
 313  */
 314 static struct bio *nilfs_alloc_seg_bio(struct super_block *sb, sector_t start,
 315                                        int nr_vecs)
 316 {
 317         struct bio *bio;
 318
 319         bio = bio_alloc(GFP_NOWAIT, nr_vecs);
 320         if (bio == NULL) {
 321                 while (!bio && (nr_vecs >>= 1))
 322                         bio = bio_alloc(GFP_NOWAIT, nr_vecs);
 323         }
 324         if (likely(bio)) {
 325                 bio->bi_bdev = sb->s_bdev;
 326                 bio->bi_sector = (sector_t)start << (sb->s_blocksize_bits - 9);
 327         }
 328         return bio;
 329 }
 330
 331 void nilfs_segbuf_prepare_write(struct nilfs_segment_buffer *segbuf,
 332                                 struct nilfs_write_info *wi)
 333 {
 334         wi->bio = NULL;
 335         wi->rest_blocks = segbuf->sb_sum.nblocks;
 336         wi->max_pages = bio_get_nr_vecs(wi->sb->s_bdev);
 337         wi->nr_vecs = min(wi->max_pages, wi->rest_blocks);
 338         wi->start = wi->end = 0;
 339         wi->nbio = 0;
 340         wi->blocknr = segbuf->sb_pseg_start;
 341
 342         atomic_set(&wi->err, 0);
 343         init_completion(&wi->bio_event);
 344 }
 345
 346 static int nilfs_submit_bh(struct nilfs_write_info *wi, struct buffer_head *bh,
 347                            int mode)
 348 {
 349         int len, err;
 350
 351         BUG_ON(wi->nr_vecs <= 0);
 352  repeat:
 353         if (!wi->bio) {
 354                 wi->bio = nilfs_alloc_seg_bio(wi->sb, wi->blocknr + wi->end,
 355                                               wi->nr_vecs);
 356                 if (unlikely(!wi->bio))
 357                         return -ENOMEM;
 358         }
 359
 360         len = bio_add_page(wi->bio, bh->b_page, bh->b_size, bh_offset(bh));
 361         if (len == bh->b_size) {
 362                 wi->end++;
 363                 return 0;
 364         }
 365         /* bio is FULL */
 366         err = nilfs_submit_seg_bio(wi, mode);
 367         /* never submit current bh */
 368         if (likely(!err))
 369                 goto repeat;
 370         return err;
 371 }
 372
 373 int nilfs_segbuf_write(struct nilfs_segment_buffer *segbuf,
 374                        struct nilfs_write_info *wi)
 375 {
 376         struct buffer_head *bh;
 377         int res, rw = WRITE;
 378
 379         list_for_each_entry(bh, &segbuf->sb_segsum_buffers, b_assoc_buffers) {
 380                 res = nilfs_submit_bh(wi, bh, rw);
 381                 if (unlikely(res))
 382                         goto failed_bio;
 383         }
 384
 385         list_for_each_entry(bh, &segbuf->sb_payload_buffers, b_assoc_buffers) {
 386                 res = nilfs_submit_bh(wi, bh, rw);
 387                 if (unlikely(res))
 388                         goto failed_bio;
 389         }
 390
 391         if (wi->bio) {
 392                 /*
 393                  * Last BIO is always sent through the following
 394                  * submission.
 395                  */
 396                 rw |= (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);
 397                 res = nilfs_submit_seg_bio(wi, rw);
 398                 if (unlikely(res))
 399                         goto failed_bio;
 400         }
 401
 402         res = 0;
 403  out:
 404         return res;
 405
 406  failed_bio:
 407         atomic_inc(&wi->err);
 408         goto out;
 409 }
 410
 411 /**
 412  * nilfs_segbuf_wait - wait for completion of requested BIOs
 413  * @wi: nilfs_write_info
 414  *
 415  * Return Value: On Success, 0 is returned. On Error, one of the following
 416  * negative error code is returned.
 417  *
 418  * %-EIO - I/O error
 419  */
 420 int nilfs_segbuf_wait(struct nilfs_segment_buffer *segbuf,
 421                       struct nilfs_write_info *wi)
 422 {
 423         int err = 0;
 424
 425         if (!wi->nbio)
 426                 return 0;
 427
 428         do {
 429                 wait_for_completion(&wi->bio_event);
 430         } while (--wi->nbio > 0);
 431
 432         if (unlikely(atomic_read(&wi->err) > 0)) {
 433                 printk(KERN_ERR "NILFS: IO error writing segment\n");
 434                 err = -EIO;
 435                 segbuf->sb_io_error = 1;
 436         }
 437         return err;
 438 }