linux/fs/jffs2/build.c
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   1/*
   2 * JFFS2 -- Journalling Flash File System, Version 2.
   3 *
   4 * Copyright © 2001-2007 Red Hat, Inc.
   5 * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
   6 *
   7 * Created by David Woodhouse <dwmw2@infradead.org>
   8 *
   9 * For licensing information, see the file 'LICENCE' in this directory.
  10 *
  11 */
  12
  13#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15#include <linux/kernel.h>
  16#include <linux/sched.h>
  17#include <linux/slab.h>
  18#include <linux/vmalloc.h>
  19#include <linux/mtd/mtd.h>
  20#include "nodelist.h"
  21
  22static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *,
  23                struct jffs2_inode_cache *, struct jffs2_full_dirent **);
  24
  25static inline struct jffs2_inode_cache *
  26first_inode_chain(int *i, struct jffs2_sb_info *c)
  27{
  28        for (; *i < c->inocache_hashsize; (*i)++) {
  29                if (c->inocache_list[*i])
  30                        return c->inocache_list[*i];
  31        }
  32        return NULL;
  33}
  34
  35static inline struct jffs2_inode_cache *
  36next_inode(int *i, struct jffs2_inode_cache *ic, struct jffs2_sb_info *c)
  37{
  38        /* More in this chain? */
  39        if (ic->next)
  40                return ic->next;
  41        (*i)++;
  42        return first_inode_chain(i, c);
  43}
  44
  45#define for_each_inode(i, c, ic)                        \
  46        for (i = 0, ic = first_inode_chain(&i, (c));    \
  47             ic;                                        \
  48             ic = next_inode(&i, ic, (c)))
  49
  50
  51static void jffs2_build_inode_pass1(struct jffs2_sb_info *c,
  52                                    struct jffs2_inode_cache *ic)
  53{
  54        struct jffs2_full_dirent *fd;
  55
  56        dbg_fsbuild("building directory inode #%u\n", ic->ino);
  57
  58        /* For each child, increase nlink */
  59        for(fd = ic->scan_dents; fd; fd = fd->next) {
  60                struct jffs2_inode_cache *child_ic;
  61                if (!fd->ino)
  62                        continue;
  63
  64                /* we can get high latency here with huge directories */
  65
  66                child_ic = jffs2_get_ino_cache(c, fd->ino);
  67                if (!child_ic) {
  68                        dbg_fsbuild("child \"%s\" (ino #%u) of dir ino #%u doesn't exist!\n",
  69                                  fd->name, fd->ino, ic->ino);
  70                        jffs2_mark_node_obsolete(c, fd->raw);
  71                        continue;
  72                }
  73
  74                if (fd->type == DT_DIR) {
  75                        if (child_ic->pino_nlink) {
  76                                JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n",
  77                                            fd->name, fd->ino, ic->ino);
  78                                /* TODO: What do we do about it? */
  79                        } else {
  80                                child_ic->pino_nlink = ic->ino;
  81                        }
  82                } else
  83                        child_ic->pino_nlink++;
  84
  85                dbg_fsbuild("increased nlink for child \"%s\" (ino #%u)\n", fd->name, fd->ino);
  86                /* Can't free scan_dents so far. We might need them in pass 2 */
  87        }
  88}
  89
  90/* Scan plan:
  91 - Scan physical nodes. Build map of inodes/dirents. Allocate inocaches as we go
  92 - Scan directory tree from top down, setting nlink in inocaches
  93 - Scan inocaches for inodes with nlink==0
  94*/
  95static int jffs2_build_filesystem(struct jffs2_sb_info *c)
  96{
  97        int ret;
  98        int i;
  99        struct jffs2_inode_cache *ic;
 100        struct jffs2_full_dirent *fd;
 101        struct jffs2_full_dirent *dead_fds = NULL;
 102
 103        dbg_fsbuild("build FS data structures\n");
 104
 105        /* First, scan the medium and build all the inode caches with
 106           lists of physical nodes */
 107
 108        c->flags |= JFFS2_SB_FLAG_SCANNING;
 109        ret = jffs2_scan_medium(c);
 110        c->flags &= ~JFFS2_SB_FLAG_SCANNING;
 111        if (ret)
 112                goto exit;
 113
 114        dbg_fsbuild("scanned flash completely\n");
 115        jffs2_dbg_dump_block_lists_nolock(c);
 116
 117        dbg_fsbuild("pass 1 starting\n");
 118        c->flags |= JFFS2_SB_FLAG_BUILDING;
 119        /* Now scan the directory tree, increasing nlink according to every dirent found. */
 120        for_each_inode(i, c, ic) {
 121                if (ic->scan_dents) {
 122                        jffs2_build_inode_pass1(c, ic);
 123                        cond_resched();
 124                }
 125        }
 126
 127        dbg_fsbuild("pass 1 complete\n");
 128
 129        /* Next, scan for inodes with nlink == 0 and remove them. If
 130           they were directories, then decrement the nlink of their
 131           children too, and repeat the scan. As that's going to be
 132           a fairly uncommon occurrence, it's not so evil to do it this
 133           way. Recursion bad. */
 134        dbg_fsbuild("pass 2 starting\n");
 135
 136        for_each_inode(i, c, ic) {
 137                if (ic->pino_nlink)
 138                        continue;
 139
 140                jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
 141                cond_resched();
 142        }
 143
 144        dbg_fsbuild("pass 2a starting\n");
 145
 146        while (dead_fds) {
 147                fd = dead_fds;
 148                dead_fds = fd->next;
 149
 150                ic = jffs2_get_ino_cache(c, fd->ino);
 151
 152                if (ic)
 153                        jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
 154                jffs2_free_full_dirent(fd);
 155        }
 156
 157        dbg_fsbuild("pass 2a complete\n");
 158        dbg_fsbuild("freeing temporary data structures\n");
 159
 160        /* Finally, we can scan again and free the dirent structs */
 161        for_each_inode(i, c, ic) {
 162                while(ic->scan_dents) {
 163                        fd = ic->scan_dents;
 164                        ic->scan_dents = fd->next;
 165                        jffs2_free_full_dirent(fd);
 166                }
 167                ic->scan_dents = NULL;
 168                cond_resched();
 169        }
 170        jffs2_build_xattr_subsystem(c);
 171        c->flags &= ~JFFS2_SB_FLAG_BUILDING;
 172
 173        dbg_fsbuild("FS build complete\n");
 174
 175        /* Rotate the lists by some number to ensure wear levelling */
 176        jffs2_rotate_lists(c);
 177
 178        ret = 0;
 179
 180exit:
 181        if (ret) {
 182                for_each_inode(i, c, ic) {
 183                        while(ic->scan_dents) {
 184                                fd = ic->scan_dents;
 185                                ic->scan_dents = fd->next;
 186                                jffs2_free_full_dirent(fd);
 187                        }
 188                }
 189                jffs2_clear_xattr_subsystem(c);
 190        }
 191
 192        return ret;
 193}
 194
 195static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *c,
 196                                        struct jffs2_inode_cache *ic,
 197                                        struct jffs2_full_dirent **dead_fds)
 198{
 199        struct jffs2_raw_node_ref *raw;
 200        struct jffs2_full_dirent *fd;
 201
 202        dbg_fsbuild("removing ino #%u with nlink == zero.\n", ic->ino);
 203
 204        raw = ic->nodes;
 205        while (raw != (void *)ic) {
 206                struct jffs2_raw_node_ref *next = raw->next_in_ino;
 207                dbg_fsbuild("obsoleting node at 0x%08x\n", ref_offset(raw));
 208                jffs2_mark_node_obsolete(c, raw);
 209                raw = next;
 210        }
 211
 212        if (ic->scan_dents) {
 213                int whinged = 0;
 214                dbg_fsbuild("inode #%u was a directory which may have children...\n", ic->ino);
 215
 216                while(ic->scan_dents) {
 217                        struct jffs2_inode_cache *child_ic;
 218
 219                        fd = ic->scan_dents;
 220                        ic->scan_dents = fd->next;
 221
 222                        if (!fd->ino) {
 223                                /* It's a deletion dirent. Ignore it */
 224                                dbg_fsbuild("child \"%s\" is a deletion dirent, skipping...\n", fd->name);
 225                                jffs2_free_full_dirent(fd);
 226                                continue;
 227                        }
 228                        if (!whinged)
 229                                whinged = 1;
 230
 231                        dbg_fsbuild("removing child \"%s\", ino #%u\n", fd->name, fd->ino);
 232
 233                        child_ic = jffs2_get_ino_cache(c, fd->ino);
 234                        if (!child_ic) {
 235                                dbg_fsbuild("cannot remove child \"%s\", ino #%u, because it doesn't exist\n",
 236                                                fd->name, fd->ino);
 237                                jffs2_free_full_dirent(fd);
 238                                continue;
 239                        }
 240
 241                        /* Reduce nlink of the child. If it's now zero, stick it on the
 242                           dead_fds list to be cleaned up later. Else just free the fd */
 243
 244                        if (fd->type == DT_DIR)
 245                                child_ic->pino_nlink = 0;
 246                        else
 247                                child_ic->pino_nlink--;
 248
 249                        if (!child_ic->pino_nlink) {
 250                                dbg_fsbuild("inode #%u (\"%s\") now has no links; adding to dead_fds list.\n",
 251                                          fd->ino, fd->name);
 252                                fd->next = *dead_fds;
 253                                *dead_fds = fd;
 254                        } else {
 255                                dbg_fsbuild("inode #%u (\"%s\") has now got nlink %d. Ignoring.\n",
 256                                          fd->ino, fd->name, child_ic->pino_nlink);
 257                                jffs2_free_full_dirent(fd);
 258                        }
 259                }
 260        }
 261
 262        /*
 263           We don't delete the inocache from the hash list and free it yet.
 264           The erase code will do that, when all the nodes are completely gone.
 265        */
 266}
 267
 268static void jffs2_calc_trigger_levels(struct jffs2_sb_info *c)
 269{
 270        uint32_t size;
 271
 272        /* Deletion should almost _always_ be allowed. We're fairly
 273           buggered once we stop allowing people to delete stuff
 274           because there's not enough free space... */
 275        c->resv_blocks_deletion = 2;
 276
 277        /* Be conservative about how much space we need before we allow writes.
 278           On top of that which is required for deletia, require an extra 2%
 279           of the medium to be available, for overhead caused by nodes being
 280           split across blocks, etc. */
 281
 282        size = c->flash_size / 50; /* 2% of flash size */
 283        size += c->nr_blocks * 100; /* And 100 bytes per eraseblock */
 284        size += c->sector_size - 1; /* ... and round up */
 285
 286        c->resv_blocks_write = c->resv_blocks_deletion + (size / c->sector_size);
 287
 288        /* When do we let the GC thread run in the background */
 289
 290        c->resv_blocks_gctrigger = c->resv_blocks_write + 1;
 291
 292        /* When do we allow garbage collection to merge nodes to make
 293           long-term progress at the expense of short-term space exhaustion? */
 294        c->resv_blocks_gcmerge = c->resv_blocks_deletion + 1;
 295
 296        /* When do we allow garbage collection to eat from bad blocks rather
 297           than actually making progress? */
 298        c->resv_blocks_gcbad = 0;//c->resv_blocks_deletion + 2;
 299
 300        /* What number of 'very dirty' eraseblocks do we allow before we
 301           trigger the GC thread even if we don't _need_ the space. When we
 302           can't mark nodes obsolete on the medium, the old dirty nodes cause
 303           performance problems because we have to inspect and discard them. */
 304        c->vdirty_blocks_gctrigger = c->resv_blocks_gctrigger;
 305        if (jffs2_can_mark_obsolete(c))
 306                c->vdirty_blocks_gctrigger *= 10;
 307
 308        /* If there's less than this amount of dirty space, don't bother
 309           trying to GC to make more space. It'll be a fruitless task */
 310        c->nospc_dirty_size = c->sector_size + (c->flash_size / 100);
 311
 312        dbg_fsbuild("trigger levels (size %d KiB, block size %d KiB, %d blocks)\n",
 313                    c->flash_size / 1024, c->sector_size / 1024, c->nr_blocks);
 314        dbg_fsbuild("Blocks required to allow deletion:    %d (%d KiB)\n",
 315                  c->resv_blocks_deletion, c->resv_blocks_deletion*c->sector_size/1024);
 316        dbg_fsbuild("Blocks required to allow writes:      %d (%d KiB)\n",
 317                  c->resv_blocks_write, c->resv_blocks_write*c->sector_size/1024);
 318        dbg_fsbuild("Blocks required to quiesce GC thread: %d (%d KiB)\n",
 319                  c->resv_blocks_gctrigger, c->resv_blocks_gctrigger*c->sector_size/1024);
 320        dbg_fsbuild("Blocks required to allow GC merges:   %d (%d KiB)\n",
 321                  c->resv_blocks_gcmerge, c->resv_blocks_gcmerge*c->sector_size/1024);
 322        dbg_fsbuild("Blocks required to GC bad blocks:     %d (%d KiB)\n",
 323                  c->resv_blocks_gcbad, c->resv_blocks_gcbad*c->sector_size/1024);
 324        dbg_fsbuild("Amount of dirty space required to GC: %d bytes\n",
 325                  c->nospc_dirty_size);
 326        dbg_fsbuild("Very dirty blocks before GC triggered: %d\n",
 327                  c->vdirty_blocks_gctrigger);
 328}
 329
 330int jffs2_do_mount_fs(struct jffs2_sb_info *c)
 331{
 332        int ret;
 333        int i;
 334        int size;
 335
 336        c->free_size = c->flash_size;
 337        c->nr_blocks = c->flash_size / c->sector_size;
 338        size = sizeof(struct jffs2_eraseblock) * c->nr_blocks;
 339#ifndef __ECOS
 340        if (jffs2_blocks_use_vmalloc(c))
 341                c->blocks = vzalloc(size);
 342        else
 343#endif
 344                c->blocks = kzalloc(size, GFP_KERNEL);
 345        if (!c->blocks)
 346                return -ENOMEM;
 347
 348        for (i=0; i<c->nr_blocks; i++) {
 349                INIT_LIST_HEAD(&c->blocks[i].list);
 350                c->blocks[i].offset = i * c->sector_size;
 351                c->blocks[i].free_size = c->sector_size;
 352        }
 353
 354        INIT_LIST_HEAD(&c->clean_list);
 355        INIT_LIST_HEAD(&c->very_dirty_list);
 356        INIT_LIST_HEAD(&c->dirty_list);
 357        INIT_LIST_HEAD(&c->erasable_list);
 358        INIT_LIST_HEAD(&c->erasing_list);
 359        INIT_LIST_HEAD(&c->erase_checking_list);
 360        INIT_LIST_HEAD(&c->erase_pending_list);
 361        INIT_LIST_HEAD(&c->erasable_pending_wbuf_list);
 362        INIT_LIST_HEAD(&c->erase_complete_list);
 363        INIT_LIST_HEAD(&c->free_list);
 364        INIT_LIST_HEAD(&c->bad_list);
 365        INIT_LIST_HEAD(&c->bad_used_list);
 366        c->highest_ino = 1;
 367        c->summary = NULL;
 368
 369        ret = jffs2_sum_init(c);
 370        if (ret)
 371                goto out_free;
 372
 373        if (jffs2_build_filesystem(c)) {
 374                dbg_fsbuild("build_fs failed\n");
 375                jffs2_free_ino_caches(c);
 376                jffs2_free_raw_node_refs(c);
 377                ret = -EIO;
 378                goto out_free;
 379        }
 380
 381        jffs2_calc_trigger_levels(c);
 382
 383        return 0;
 384
 385 out_free:
 386#ifndef __ECOS
 387        if (jffs2_blocks_use_vmalloc(c))
 388                vfree(c->blocks);
 389        else
 390#endif
 391                kfree(c->blocks);
 392
 393        return ret;
 394}
 395
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