linux/fs/logfs/super.c
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   1/*
   2 * fs/logfs/super.c
   3 *
   4 * As should be obvious for Linux kernel code, license is GPLv2
   5 *
   6 * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
   7 *
   8 * Generally contains mount/umount code and also serves as a dump area for
   9 * any functions that don't fit elsewhere and neither justify a file of their
  10 * own.
  11 */
  12#include "logfs.h"
  13#include <linux/bio.h>
  14#include <linux/slab.h>
  15#include <linux/blkdev.h>
  16#include <linux/module.h>
  17#include <linux/mtd/mtd.h>
  18#include <linux/statfs.h>
  19#include <linux/buffer_head.h>
  20
  21static DEFINE_MUTEX(emergency_mutex);
  22static struct page *emergency_page;
  23
  24struct page *emergency_read_begin(struct address_space *mapping, pgoff_t index)
  25{
  26        filler_t *filler = (filler_t *)mapping->a_ops->readpage;
  27        struct page *page;
  28        int err;
  29
  30        page = read_cache_page(mapping, index, filler, NULL);
  31        if (page)
  32                return page;
  33
  34        /* No more pages available, switch to emergency page */
  35        printk(KERN_INFO"Logfs: Using emergency page\n");
  36        mutex_lock(&emergency_mutex);
  37        err = filler(NULL, emergency_page);
  38        if (err) {
  39                mutex_unlock(&emergency_mutex);
  40                printk(KERN_EMERG"Logfs: Error reading emergency page\n");
  41                return ERR_PTR(err);
  42        }
  43        return emergency_page;
  44}
  45
  46void emergency_read_end(struct page *page)
  47{
  48        if (page == emergency_page)
  49                mutex_unlock(&emergency_mutex);
  50        else
  51                page_cache_release(page);
  52}
  53
  54static void dump_segfile(struct super_block *sb)
  55{
  56        struct logfs_super *super = logfs_super(sb);
  57        struct logfs_segment_entry se;
  58        u32 segno;
  59
  60        for (segno = 0; segno < super->s_no_segs; segno++) {
  61                logfs_get_segment_entry(sb, segno, &se);
  62                printk("%3x: %6x %8x", segno, be32_to_cpu(se.ec_level),
  63                                be32_to_cpu(se.valid));
  64                if (++segno < super->s_no_segs) {
  65                        logfs_get_segment_entry(sb, segno, &se);
  66                        printk(" %6x %8x", be32_to_cpu(se.ec_level),
  67                                        be32_to_cpu(se.valid));
  68                }
  69                if (++segno < super->s_no_segs) {
  70                        logfs_get_segment_entry(sb, segno, &se);
  71                        printk(" %6x %8x", be32_to_cpu(se.ec_level),
  72                                        be32_to_cpu(se.valid));
  73                }
  74                if (++segno < super->s_no_segs) {
  75                        logfs_get_segment_entry(sb, segno, &se);
  76                        printk(" %6x %8x", be32_to_cpu(se.ec_level),
  77                                        be32_to_cpu(se.valid));
  78                }
  79                printk("\n");
  80        }
  81}
  82
  83/*
  84 * logfs_crash_dump - dump debug information to device
  85 *
  86 * The LogFS superblock only occupies part of a segment.  This function will
  87 * write as much debug information as it can gather into the spare space.
  88 */
  89void logfs_crash_dump(struct super_block *sb)
  90{
  91        dump_segfile(sb);
  92}
  93
  94/*
  95 * FIXME: There should be a reserve for root, similar to ext2.
  96 */
  97int logfs_statfs(struct dentry *dentry, struct kstatfs *stats)
  98{
  99        struct super_block *sb = dentry->d_sb;
 100        struct logfs_super *super = logfs_super(sb);
 101
 102        stats->f_type           = LOGFS_MAGIC_U32;
 103        stats->f_bsize          = sb->s_blocksize;
 104        stats->f_blocks         = super->s_size >> LOGFS_BLOCK_BITS >> 3;
 105        stats->f_bfree          = super->s_free_bytes >> sb->s_blocksize_bits;
 106        stats->f_bavail         = super->s_free_bytes >> sb->s_blocksize_bits;
 107        stats->f_files          = 0;
 108        stats->f_ffree          = 0;
 109        stats->f_namelen        = LOGFS_MAX_NAMELEN;
 110        return 0;
 111}
 112
 113static int logfs_sb_set(struct super_block *sb, void *_super)
 114{
 115        struct logfs_super *super = _super;
 116
 117        sb->s_fs_info = super;
 118        sb->s_mtd = super->s_mtd;
 119        sb->s_bdev = super->s_bdev;
 120#ifdef CONFIG_BLOCK
 121        if (sb->s_bdev)
 122                sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
 123#endif
 124#ifdef CONFIG_MTD
 125        if (sb->s_mtd)
 126                sb->s_bdi = sb->s_mtd->backing_dev_info;
 127#endif
 128        return 0;
 129}
 130
 131static int logfs_sb_test(struct super_block *sb, void *_super)
 132{
 133        struct logfs_super *super = _super;
 134        struct mtd_info *mtd = super->s_mtd;
 135
 136        if (mtd && sb->s_mtd == mtd)
 137                return 1;
 138        if (super->s_bdev && sb->s_bdev == super->s_bdev)
 139                return 1;
 140        return 0;
 141}
 142
 143static void set_segment_header(struct logfs_segment_header *sh, u8 type,
 144                u8 level, u32 segno, u32 ec)
 145{
 146        sh->pad = 0;
 147        sh->type = type;
 148        sh->level = level;
 149        sh->segno = cpu_to_be32(segno);
 150        sh->ec = cpu_to_be32(ec);
 151        sh->gec = cpu_to_be64(segno);
 152        sh->crc = logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4);
 153}
 154
 155static void logfs_write_ds(struct super_block *sb, struct logfs_disk_super *ds,
 156                u32 segno, u32 ec)
 157{
 158        struct logfs_super *super = logfs_super(sb);
 159        struct logfs_segment_header *sh = &ds->ds_sh;
 160        int i;
 161
 162        memset(ds, 0, sizeof(*ds));
 163        set_segment_header(sh, SEG_SUPER, 0, segno, ec);
 164
 165        ds->ds_ifile_levels     = super->s_ifile_levels;
 166        ds->ds_iblock_levels    = super->s_iblock_levels;
 167        ds->ds_data_levels      = super->s_data_levels; /* XXX: Remove */
 168        ds->ds_segment_shift    = super->s_segshift;
 169        ds->ds_block_shift      = sb->s_blocksize_bits;
 170        ds->ds_write_shift      = super->s_writeshift;
 171        ds->ds_filesystem_size  = cpu_to_be64(super->s_size);
 172        ds->ds_segment_size     = cpu_to_be32(super->s_segsize);
 173        ds->ds_bad_seg_reserve  = cpu_to_be32(super->s_bad_seg_reserve);
 174        ds->ds_feature_incompat = cpu_to_be64(super->s_feature_incompat);
 175        ds->ds_feature_ro_compat= cpu_to_be64(super->s_feature_ro_compat);
 176        ds->ds_feature_compat   = cpu_to_be64(super->s_feature_compat);
 177        ds->ds_feature_flags    = cpu_to_be64(super->s_feature_flags);
 178        ds->ds_root_reserve     = cpu_to_be64(super->s_root_reserve);
 179        ds->ds_speed_reserve    = cpu_to_be64(super->s_speed_reserve);
 180        journal_for_each(i)
 181                ds->ds_journal_seg[i] = cpu_to_be32(super->s_journal_seg[i]);
 182        ds->ds_magic            = cpu_to_be64(LOGFS_MAGIC);
 183        ds->ds_crc = logfs_crc32(ds, sizeof(*ds),
 184                        LOGFS_SEGMENT_HEADERSIZE + 12);
 185}
 186
 187static int write_one_sb(struct super_block *sb,
 188                struct page *(*find_sb)(struct super_block *sb, u64 *ofs))
 189{
 190        struct logfs_super *super = logfs_super(sb);
 191        struct logfs_disk_super *ds;
 192        struct logfs_segment_entry se;
 193        struct page *page;
 194        u64 ofs;
 195        u32 ec, segno;
 196        int err;
 197
 198        page = find_sb(sb, &ofs);
 199        if (!page)
 200                return -EIO;
 201        ds = page_address(page);
 202        segno = seg_no(sb, ofs);
 203        logfs_get_segment_entry(sb, segno, &se);
 204        ec = be32_to_cpu(se.ec_level) >> 4;
 205        ec++;
 206        logfs_set_segment_erased(sb, segno, ec, 0);
 207        logfs_write_ds(sb, ds, segno, ec);
 208        err = super->s_devops->write_sb(sb, page);
 209        page_cache_release(page);
 210        return err;
 211}
 212
 213int logfs_write_sb(struct super_block *sb)
 214{
 215        struct logfs_super *super = logfs_super(sb);
 216        int err;
 217
 218        /* First superblock */
 219        err = write_one_sb(sb, super->s_devops->find_first_sb);
 220        if (err)
 221                return err;
 222
 223        /* Last superblock */
 224        err = write_one_sb(sb, super->s_devops->find_last_sb);
 225        if (err)
 226                return err;
 227        return 0;
 228}
 229
 230static int ds_cmp(const void *ds0, const void *ds1)
 231{
 232        size_t len = sizeof(struct logfs_disk_super);
 233
 234        /* We know the segment headers differ, so ignore them */
 235        len -= LOGFS_SEGMENT_HEADERSIZE;
 236        ds0 += LOGFS_SEGMENT_HEADERSIZE;
 237        ds1 += LOGFS_SEGMENT_HEADERSIZE;
 238        return memcmp(ds0, ds1, len);
 239}
 240
 241static int logfs_recover_sb(struct super_block *sb)
 242{
 243        struct logfs_super *super = logfs_super(sb);
 244        struct logfs_disk_super _ds0, *ds0 = &_ds0;
 245        struct logfs_disk_super _ds1, *ds1 = &_ds1;
 246        int err, valid0, valid1;
 247
 248        /* read first superblock */
 249        err = wbuf_read(sb, super->s_sb_ofs[0], sizeof(*ds0), ds0);
 250        if (err)
 251                return err;
 252        /* read last superblock */
 253        err = wbuf_read(sb, super->s_sb_ofs[1], sizeof(*ds1), ds1);
 254        if (err)
 255                return err;
 256        valid0 = logfs_check_ds(ds0) == 0;
 257        valid1 = logfs_check_ds(ds1) == 0;
 258
 259        if (!valid0 && valid1) {
 260                printk(KERN_INFO"First superblock is invalid - fixing.\n");
 261                return write_one_sb(sb, super->s_devops->find_first_sb);
 262        }
 263        if (valid0 && !valid1) {
 264                printk(KERN_INFO"Last superblock is invalid - fixing.\n");
 265                return write_one_sb(sb, super->s_devops->find_last_sb);
 266        }
 267        if (valid0 && valid1 && ds_cmp(ds0, ds1)) {
 268                printk(KERN_INFO"Superblocks don't match - fixing.\n");
 269                return logfs_write_sb(sb);
 270        }
 271        /* If neither is valid now, something's wrong.  Didn't we properly
 272         * check them before?!? */
 273        BUG_ON(!valid0 && !valid1);
 274        return 0;
 275}
 276
 277static int logfs_make_writeable(struct super_block *sb)
 278{
 279        int err;
 280
 281        err = logfs_open_segfile(sb);
 282        if (err)
 283                return err;
 284
 285        /* Repair any broken superblock copies */
 286        err = logfs_recover_sb(sb);
 287        if (err)
 288                return err;
 289
 290        /* Check areas for trailing unaccounted data */
 291        err = logfs_check_areas(sb);
 292        if (err)
 293                return err;
 294
 295        /* Do one GC pass before any data gets dirtied */
 296        logfs_gc_pass(sb);
 297
 298        /* after all initializations are done, replay the journal
 299         * for rw-mounts, if necessary */
 300        err = logfs_replay_journal(sb);
 301        if (err)
 302                return err;
 303
 304        return 0;
 305}
 306
 307static int logfs_get_sb_final(struct super_block *sb)
 308{
 309        struct logfs_super *super = logfs_super(sb);
 310        struct inode *rootdir;
 311        int err;
 312
 313        /* root dir */
 314        rootdir = logfs_iget(sb, LOGFS_INO_ROOT);
 315        if (IS_ERR(rootdir))
 316                goto fail;
 317
 318        sb->s_root = d_make_root(rootdir);
 319        if (!sb->s_root)
 320                goto fail;
 321
 322        /* at that point we know that ->put_super() will be called */
 323        super->s_erase_page = alloc_pages(GFP_KERNEL, 0);
 324        if (!super->s_erase_page)
 325                return -ENOMEM;
 326        memset(page_address(super->s_erase_page), 0xFF, PAGE_SIZE);
 327
 328        /* FIXME: check for read-only mounts */
 329        err = logfs_make_writeable(sb);
 330        if (err) {
 331                __free_page(super->s_erase_page);
 332                return err;
 333        }
 334
 335        log_super("LogFS: Finished mounting\n");
 336        return 0;
 337
 338fail:
 339        iput(super->s_master_inode);
 340        iput(super->s_segfile_inode);
 341        iput(super->s_mapping_inode);
 342        return -EIO;
 343}
 344
 345int logfs_check_ds(struct logfs_disk_super *ds)
 346{
 347        struct logfs_segment_header *sh = &ds->ds_sh;
 348
 349        if (ds->ds_magic != cpu_to_be64(LOGFS_MAGIC))
 350                return -EINVAL;
 351        if (sh->crc != logfs_crc32(sh, LOGFS_SEGMENT_HEADERSIZE, 4))
 352                return -EINVAL;
 353        if (ds->ds_crc != logfs_crc32(ds, sizeof(*ds),
 354                                LOGFS_SEGMENT_HEADERSIZE + 12))
 355                return -EINVAL;
 356        return 0;
 357}
 358
 359static struct page *find_super_block(struct super_block *sb)
 360{
 361        struct logfs_super *super = logfs_super(sb);
 362        struct page *first, *last;
 363
 364        first = super->s_devops->find_first_sb(sb, &super->s_sb_ofs[0]);
 365        if (!first || IS_ERR(first))
 366                return NULL;
 367        last = super->s_devops->find_last_sb(sb, &super->s_sb_ofs[1]);
 368        if (!last || IS_ERR(last)) {
 369                page_cache_release(first);
 370                return NULL;
 371        }
 372
 373        if (!logfs_check_ds(page_address(first))) {
 374                page_cache_release(last);
 375                return first;
 376        }
 377
 378        /* First one didn't work, try the second superblock */
 379        if (!logfs_check_ds(page_address(last))) {
 380                page_cache_release(first);
 381                return last;
 382        }
 383
 384        /* Neither worked, sorry folks */
 385        page_cache_release(first);
 386        page_cache_release(last);
 387        return NULL;
 388}
 389
 390static int __logfs_read_sb(struct super_block *sb)
 391{
 392        struct logfs_super *super = logfs_super(sb);
 393        struct page *page;
 394        struct logfs_disk_super *ds;
 395        int i;
 396
 397        page = find_super_block(sb);
 398        if (!page)
 399                return -EINVAL;
 400
 401        ds = page_address(page);
 402        super->s_size = be64_to_cpu(ds->ds_filesystem_size);
 403        super->s_root_reserve = be64_to_cpu(ds->ds_root_reserve);
 404        super->s_speed_reserve = be64_to_cpu(ds->ds_speed_reserve);
 405        super->s_bad_seg_reserve = be32_to_cpu(ds->ds_bad_seg_reserve);
 406        super->s_segsize = 1 << ds->ds_segment_shift;
 407        super->s_segmask = (1 << ds->ds_segment_shift) - 1;
 408        super->s_segshift = ds->ds_segment_shift;
 409        sb->s_blocksize = 1 << ds->ds_block_shift;
 410        sb->s_blocksize_bits = ds->ds_block_shift;
 411        super->s_writesize = 1 << ds->ds_write_shift;
 412        super->s_writeshift = ds->ds_write_shift;
 413        super->s_no_segs = super->s_size >> super->s_segshift;
 414        super->s_no_blocks = super->s_segsize >> sb->s_blocksize_bits;
 415        super->s_feature_incompat = be64_to_cpu(ds->ds_feature_incompat);
 416        super->s_feature_ro_compat = be64_to_cpu(ds->ds_feature_ro_compat);
 417        super->s_feature_compat = be64_to_cpu(ds->ds_feature_compat);
 418        super->s_feature_flags = be64_to_cpu(ds->ds_feature_flags);
 419
 420        journal_for_each(i)
 421                super->s_journal_seg[i] = be32_to_cpu(ds->ds_journal_seg[i]);
 422
 423        super->s_ifile_levels = ds->ds_ifile_levels;
 424        super->s_iblock_levels = ds->ds_iblock_levels;
 425        super->s_data_levels = ds->ds_data_levels;
 426        super->s_total_levels = super->s_ifile_levels + super->s_iblock_levels
 427                + super->s_data_levels;
 428        page_cache_release(page);
 429        return 0;
 430}
 431
 432static int logfs_read_sb(struct super_block *sb, int read_only)
 433{
 434        struct logfs_super *super = logfs_super(sb);
 435        int ret;
 436
 437        super->s_btree_pool = mempool_create(32, btree_alloc, btree_free, NULL);
 438        if (!super->s_btree_pool)
 439                return -ENOMEM;
 440
 441        btree_init_mempool64(&super->s_shadow_tree.new, super->s_btree_pool);
 442        btree_init_mempool64(&super->s_shadow_tree.old, super->s_btree_pool);
 443        btree_init_mempool32(&super->s_shadow_tree.segment_map,
 444                        super->s_btree_pool);
 445
 446        ret = logfs_init_mapping(sb);
 447        if (ret)
 448                return ret;
 449
 450        ret = __logfs_read_sb(sb);
 451        if (ret)
 452                return ret;
 453
 454        if (super->s_feature_incompat & ~LOGFS_FEATURES_INCOMPAT)
 455                return -EIO;
 456        if ((super->s_feature_ro_compat & ~LOGFS_FEATURES_RO_COMPAT) &&
 457                        !read_only)
 458                return -EIO;
 459
 460        ret = logfs_init_rw(sb);
 461        if (ret)
 462                return ret;
 463
 464        ret = logfs_init_areas(sb);
 465        if (ret)
 466                return ret;
 467
 468        ret = logfs_init_gc(sb);
 469        if (ret)
 470                return ret;
 471
 472        ret = logfs_init_journal(sb);
 473        if (ret)
 474                return ret;
 475
 476        return 0;
 477}
 478
 479static void logfs_kill_sb(struct super_block *sb)
 480{
 481        struct logfs_super *super = logfs_super(sb);
 482
 483        log_super("LogFS: Start unmounting\n");
 484        /* Alias entries slow down mount, so evict as many as possible */
 485        sync_filesystem(sb);
 486        logfs_write_anchor(sb);
 487        free_areas(sb);
 488
 489        /*
 490         * From this point on alias entries are simply dropped - and any
 491         * writes to the object store are considered bugs.
 492         */
 493        log_super("LogFS: Now in shutdown\n");
 494        generic_shutdown_super(sb);
 495        super->s_flags |= LOGFS_SB_FLAG_SHUTDOWN;
 496
 497        BUG_ON(super->s_dirty_used_bytes || super->s_dirty_free_bytes);
 498
 499        logfs_cleanup_gc(sb);
 500        logfs_cleanup_journal(sb);
 501        logfs_cleanup_areas(sb);
 502        logfs_cleanup_rw(sb);
 503        if (super->s_erase_page)
 504                __free_page(super->s_erase_page);
 505        super->s_devops->put_device(super);
 506        logfs_mempool_destroy(super->s_btree_pool);
 507        logfs_mempool_destroy(super->s_alias_pool);
 508        kfree(super);
 509        log_super("LogFS: Finished unmounting\n");
 510}
 511
 512static struct dentry *logfs_get_sb_device(struct logfs_super *super,
 513                struct file_system_type *type, int flags)
 514{
 515        struct super_block *sb;
 516        int err = -ENOMEM;
 517        static int mount_count;
 518
 519        log_super("LogFS: Start mount %x\n", mount_count++);
 520
 521        err = -EINVAL;
 522        sb = sget(type, logfs_sb_test, logfs_sb_set, flags | MS_NOATIME, super);
 523        if (IS_ERR(sb)) {
 524                super->s_devops->put_device(super);
 525                kfree(super);
 526                return ERR_CAST(sb);
 527        }
 528
 529        if (sb->s_root) {
 530                /* Device is already in use */
 531                super->s_devops->put_device(super);
 532                kfree(super);
 533                return dget(sb->s_root);
 534        }
 535
 536        /*
 537         * sb->s_maxbytes is limited to 8TB.  On 32bit systems, the page cache
 538         * only covers 16TB and the upper 8TB are used for indirect blocks.
 539         * On 64bit system we could bump up the limit, but that would make
 540         * the filesystem incompatible with 32bit systems.
 541         */
 542        sb->s_maxbytes  = (1ull << 43) - 1;
 543        sb->s_max_links = LOGFS_LINK_MAX;
 544        sb->s_op        = &logfs_super_operations;
 545
 546        err = logfs_read_sb(sb, sb->s_flags & MS_RDONLY);
 547        if (err)
 548                goto err1;
 549
 550        sb->s_flags |= MS_ACTIVE;
 551        err = logfs_get_sb_final(sb);
 552        if (err) {
 553                deactivate_locked_super(sb);
 554                return ERR_PTR(err);
 555        }
 556        return dget(sb->s_root);
 557
 558err1:
 559        /* no ->s_root, no ->put_super() */
 560        iput(super->s_master_inode);
 561        iput(super->s_segfile_inode);
 562        iput(super->s_mapping_inode);
 563        deactivate_locked_super(sb);
 564        return ERR_PTR(err);
 565}
 566
 567static struct dentry *logfs_mount(struct file_system_type *type, int flags,
 568                const char *devname, void *data)
 569{
 570        ulong mtdnr;
 571        struct logfs_super *super;
 572        int err;
 573
 574        super = kzalloc(sizeof(*super), GFP_KERNEL);
 575        if (!super)
 576                return ERR_PTR(-ENOMEM);
 577
 578        mutex_init(&super->s_dirop_mutex);
 579        mutex_init(&super->s_object_alias_mutex);
 580        INIT_LIST_HEAD(&super->s_freeing_list);
 581
 582        if (!devname)
 583                err = logfs_get_sb_bdev(super, type, devname);
 584        else if (strncmp(devname, "mtd", 3))
 585                err = logfs_get_sb_bdev(super, type, devname);
 586        else {
 587                char *garbage;
 588                mtdnr = simple_strtoul(devname+3, &garbage, 0);
 589                if (*garbage)
 590                        err = -EINVAL;
 591                else
 592                        err = logfs_get_sb_mtd(super, mtdnr);
 593        }
 594
 595        if (err) {
 596                kfree(super);
 597                return ERR_PTR(err);
 598        }
 599
 600        return logfs_get_sb_device(super, type, flags);
 601}
 602
 603static struct file_system_type logfs_fs_type = {
 604        .owner          = THIS_MODULE,
 605        .name           = "logfs",
 606        .mount          = logfs_mount,
 607        .kill_sb        = logfs_kill_sb,
 608        .fs_flags       = FS_REQUIRES_DEV,
 609
 610};
 611
 612static int __init logfs_init(void)
 613{
 614        int ret;
 615
 616        emergency_page = alloc_pages(GFP_KERNEL, 0);
 617        if (!emergency_page)
 618                return -ENOMEM;
 619
 620        ret = logfs_compr_init();
 621        if (ret)
 622                goto out1;
 623
 624        ret = logfs_init_inode_cache();
 625        if (ret)
 626                goto out2;
 627
 628        ret = register_filesystem(&logfs_fs_type);
 629        if (!ret)
 630                return 0;
 631        logfs_destroy_inode_cache();
 632out2:
 633        logfs_compr_exit();
 634out1:
 635        __free_pages(emergency_page, 0);
 636        return ret;
 637}
 638
 639static void __exit logfs_exit(void)
 640{
 641        unregister_filesystem(&logfs_fs_type);
 642        logfs_destroy_inode_cache();
 643        logfs_compr_exit();
 644        __free_pages(emergency_page, 0);
 645}
 646
 647module_init(logfs_init);
 648module_exit(logfs_exit);
 649
 650MODULE_LICENSE("GPL v2");
 651MODULE_AUTHOR("Joern Engel <joern@logfs.org>");
 652MODULE_DESCRIPTION("scalable flash filesystem");
 653
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