linux/fs/jffs2/build.c
<<
>>
Prefs
   1/*
   2 * JFFS2 -- Journalling Flash File System, Version 2.
   3 *
   4 * Copyright © 2001-2007 Red Hat, Inc.
   5 *
   6 * Created by David Woodhouse <dwmw2@infradead.org>
   7 *
   8 * For licensing information, see the file 'LICENCE' in this directory.
   9 *
  10 */
  11
  12#include <linux/kernel.h>
  13#include <linux/sched.h>
  14#include <linux/slab.h>
  15#include <linux/vmalloc.h>
  16#include <linux/mtd/mtd.h>
  17#include "nodelist.h"
  18
  19static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *,
  20                struct jffs2_inode_cache *, struct jffs2_full_dirent **);
  21
  22static inline struct jffs2_inode_cache *
  23first_inode_chain(int *i, struct jffs2_sb_info *c)
  24{
  25        for (; *i < INOCACHE_HASHSIZE; (*i)++) {
  26                if (c->inocache_list[*i])
  27                        return c->inocache_list[*i];
  28        }
  29        return NULL;
  30}
  31
  32static inline struct jffs2_inode_cache *
  33next_inode(int *i, struct jffs2_inode_cache *ic, struct jffs2_sb_info *c)
  34{
  35        /* More in this chain? */
  36        if (ic->next)
  37                return ic->next;
  38        (*i)++;
  39        return first_inode_chain(i, c);
  40}
  41
  42#define for_each_inode(i, c, ic)                        \
  43        for (i = 0, ic = first_inode_chain(&i, (c));    \
  44             ic;                                        \
  45             ic = next_inode(&i, ic, (c)))
  46
  47
  48static void jffs2_build_inode_pass1(struct jffs2_sb_info *c,
  49                                    struct jffs2_inode_cache *ic)
  50{
  51        struct jffs2_full_dirent *fd;
  52
  53        dbg_fsbuild("building directory inode #%u\n", ic->ino);
  54
  55        /* For each child, increase nlink */
  56        for(fd = ic->scan_dents; fd; fd = fd->next) {
  57                struct jffs2_inode_cache *child_ic;
  58                if (!fd->ino)
  59                        continue;
  60
  61                /* we can get high latency here with huge directories */
  62
  63                child_ic = jffs2_get_ino_cache(c, fd->ino);
  64                if (!child_ic) {
  65                        dbg_fsbuild("child \"%s\" (ino #%u) of dir ino #%u doesn't exist!\n",
  66                                  fd->name, fd->ino, ic->ino);
  67                        jffs2_mark_node_obsolete(c, fd->raw);
  68                        continue;
  69                }
  70
  71                if (fd->type == DT_DIR) {
  72                        if (child_ic->pino_nlink) {
  73                                JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n",
  74                                            fd->name, fd->ino, ic->ino);
  75                                /* TODO: What do we do about it? */
  76                        } else {
  77                                child_ic->pino_nlink = ic->ino;
  78                        }
  79                } else
  80                        child_ic->pino_nlink++;
  81
  82                dbg_fsbuild("increased nlink for child \"%s\" (ino #%u)\n", fd->name, fd->ino);
  83                /* Can't free scan_dents so far. We might need them in pass 2 */
  84        }
  85}
  86
  87/* Scan plan:
  88 - Scan physical nodes. Build map of inodes/dirents. Allocate inocaches as we go
  89 - Scan directory tree from top down, setting nlink in inocaches
  90 - Scan inocaches for inodes with nlink==0
  91*/
  92static int jffs2_build_filesystem(struct jffs2_sb_info *c)
  93{
  94        int ret;
  95        int i;
  96        struct jffs2_inode_cache *ic;
  97        struct jffs2_full_dirent *fd;
  98        struct jffs2_full_dirent *dead_fds = NULL;
  99
 100        dbg_fsbuild("build FS data structures\n");
 101
 102        /* First, scan the medium and build all the inode caches with
 103           lists of physical nodes */
 104
 105        c->flags |= JFFS2_SB_FLAG_SCANNING;
 106        ret = jffs2_scan_medium(c);
 107        c->flags &= ~JFFS2_SB_FLAG_SCANNING;
 108        if (ret)
 109                goto exit;
 110
 111        dbg_fsbuild("scanned flash completely\n");
 112        jffs2_dbg_dump_block_lists_nolock(c);
 113
 114        dbg_fsbuild("pass 1 starting\n");
 115        c->flags |= JFFS2_SB_FLAG_BUILDING;
 116        /* Now scan the directory tree, increasing nlink according to every dirent found. */
 117        for_each_inode(i, c, ic) {
 118                if (ic->scan_dents) {
 119                        jffs2_build_inode_pass1(c, ic);
 120                        cond_resched();
 121                }
 122        }
 123
 124        dbg_fsbuild("pass 1 complete\n");
 125
 126        /* Next, scan for inodes with nlink == 0 and remove them. If
 127           they were directories, then decrement the nlink of their
 128           children too, and repeat the scan. As that's going to be
 129           a fairly uncommon occurrence, it's not so evil to do it this
 130           way. Recursion bad. */
 131        dbg_fsbuild("pass 2 starting\n");
 132
 133        for_each_inode(i, c, ic) {
 134                if (ic->pino_nlink)
 135                        continue;
 136
 137                jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
 138                cond_resched();
 139        }
 140
 141        dbg_fsbuild("pass 2a starting\n");
 142
 143        while (dead_fds) {
 144                fd = dead_fds;
 145                dead_fds = fd->next;
 146
 147                ic = jffs2_get_ino_cache(c, fd->ino);
 148
 149                if (ic)
 150                        jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
 151                jffs2_free_full_dirent(fd);
 152        }
 153
 154        dbg_fsbuild("pass 2a complete\n");
 155        dbg_fsbuild("freeing temporary data structures\n");
 156
 157        /* Finally, we can scan again and free the dirent structs */
 158        for_each_inode(i, c, ic) {
 159                while(ic->scan_dents) {
 160                        fd = ic->scan_dents;
 161                        ic->scan_dents = fd->next;
 162                        jffs2_free_full_dirent(fd);
 163                }
 164                ic->scan_dents = NULL;
 165                cond_resched();
 166        }
 167        jffs2_build_xattr_subsystem(c);
 168        c->flags &= ~JFFS2_SB_FLAG_BUILDING;
 169
 170        dbg_fsbuild("FS build complete\n");
 171
 172        /* Rotate the lists by some number to ensure wear levelling */
 173        jffs2_rotate_lists(c);
 174
 175        ret = 0;
 176
 177exit:
 178        if (ret) {
 179                for_each_inode(i, c, ic) {
 180                        while(ic->scan_dents) {
 181                                fd = ic->scan_dents;
 182                                ic->scan_dents = fd->next;
 183                                jffs2_free_full_dirent(fd);
 184                        }
 185                }
 186                jffs2_clear_xattr_subsystem(c);
 187        }
 188
 189        return ret;
 190}
 191
 192static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *c,
 193                                        struct jffs2_inode_cache *ic,
 194                                        struct jffs2_full_dirent **dead_fds)
 195{
 196        struct jffs2_raw_node_ref *raw;
 197        struct jffs2_full_dirent *fd;
 198
 199        dbg_fsbuild("removing ino #%u with nlink == zero.\n", ic->ino);
 200
 201        raw = ic->nodes;
 202        while (raw != (void *)ic) {
 203                struct jffs2_raw_node_ref *next = raw->next_in_ino;
 204                dbg_fsbuild("obsoleting node at 0x%08x\n", ref_offset(raw));
 205                jffs2_mark_node_obsolete(c, raw);
 206                raw = next;
 207        }
 208
 209        if (ic->scan_dents) {
 210                int whinged = 0;
 211                dbg_fsbuild("inode #%u was a directory which may have children...\n", ic->ino);
 212
 213                while(ic->scan_dents) {
 214                        struct jffs2_inode_cache *child_ic;
 215
 216                        fd = ic->scan_dents;
 217                        ic->scan_dents = fd->next;
 218
 219                        if (!fd->ino) {
 220                                /* It's a deletion dirent. Ignore it */
 221                                dbg_fsbuild("child \"%s\" is a deletion dirent, skipping...\n", fd->name);
 222                                jffs2_free_full_dirent(fd);
 223                                continue;
 224                        }
 225                        if (!whinged)
 226                                whinged = 1;
 227
 228                        dbg_fsbuild("removing child \"%s\", ino #%u\n", fd->name, fd->ino);
 229
 230                        child_ic = jffs2_get_ino_cache(c, fd->ino);
 231                        if (!child_ic) {
 232                                dbg_fsbuild("cannot remove child \"%s\", ino #%u, because it doesn't exist\n",
 233                                                fd->name, fd->ino);
 234                                jffs2_free_full_dirent(fd);
 235                                continue;
 236                        }
 237
 238                        /* Reduce nlink of the child. If it's now zero, stick it on the
 239                           dead_fds list to be cleaned up later. Else just free the fd */
 240
 241                        if (fd->type == DT_DIR)
 242                                child_ic->pino_nlink = 0;
 243                        else
 244                                child_ic->pino_nlink--;
 245
 246                        if (!child_ic->pino_nlink) {
 247                                dbg_fsbuild("inode #%u (\"%s\") now has no links; adding to dead_fds list.\n",
 248                                          fd->ino, fd->name);
 249                                fd->next = *dead_fds;
 250                                *dead_fds = fd;
 251                        } else {
 252                                dbg_fsbuild("inode #%u (\"%s\") has now got nlink %d. Ignoring.\n",
 253                                          fd->ino, fd->name, child_ic->pino_nlink);
 254                                jffs2_free_full_dirent(fd);
 255                        }
 256                }
 257        }
 258
 259        /*
 260           We don't delete the inocache from the hash list and free it yet.
 261           The erase code will do that, when all the nodes are completely gone.
 262        */
 263}
 264
 265static void jffs2_calc_trigger_levels(struct jffs2_sb_info *c)
 266{
 267        uint32_t size;
 268
 269        /* Deletion should almost _always_ be allowed. We're fairly
 270           buggered once we stop allowing people to delete stuff
 271           because there's not enough free space... */
 272        c->resv_blocks_deletion = 2;
 273
 274        /* Be conservative about how much space we need before we allow writes.
 275           On top of that which is required for deletia, require an extra 2%
 276           of the medium to be available, for overhead caused by nodes being
 277           split across blocks, etc. */
 278
 279        size = c->flash_size / 50; /* 2% of flash size */
 280        size += c->nr_blocks * 100; /* And 100 bytes per eraseblock */
 281        size += c->sector_size - 1; /* ... and round up */
 282
 283        c->resv_blocks_write = c->resv_blocks_deletion + (size / c->sector_size);
 284
 285        /* When do we let the GC thread run in the background */
 286
 287        c->resv_blocks_gctrigger = c->resv_blocks_write + 1;
 288
 289        /* When do we allow garbage collection to merge nodes to make
 290           long-term progress at the expense of short-term space exhaustion? */
 291        c->resv_blocks_gcmerge = c->resv_blocks_deletion + 1;
 292
 293        /* When do we allow garbage collection to eat from bad blocks rather
 294           than actually making progress? */
 295        c->resv_blocks_gcbad = 0;//c->resv_blocks_deletion + 2;
 296
 297        /* What number of 'very dirty' eraseblocks do we allow before we
 298           trigger the GC thread even if we don't _need_ the space. When we
 299           can't mark nodes obsolete on the medium, the old dirty nodes cause
 300           performance problems because we have to inspect and discard them. */
 301        c->vdirty_blocks_gctrigger = c->resv_blocks_gctrigger;
 302        if (jffs2_can_mark_obsolete(c))
 303                c->vdirty_blocks_gctrigger *= 10;
 304
 305        /* If there's less than this amount of dirty space, don't bother
 306           trying to GC to make more space. It'll be a fruitless task */
 307        c->nospc_dirty_size = c->sector_size + (c->flash_size / 100);
 308
 309        dbg_fsbuild("JFFS2 trigger levels (size %d KiB, block size %d KiB, %d blocks)\n",
 310                  c->flash_size / 1024, c->sector_size / 1024, c->nr_blocks);
 311        dbg_fsbuild("Blocks required to allow deletion:    %d (%d KiB)\n",
 312                  c->resv_blocks_deletion, c->resv_blocks_deletion*c->sector_size/1024);
 313        dbg_fsbuild("Blocks required to allow writes:      %d (%d KiB)\n",
 314                  c->resv_blocks_write, c->resv_blocks_write*c->sector_size/1024);
 315        dbg_fsbuild("Blocks required to quiesce GC thread: %d (%d KiB)\n",
 316                  c->resv_blocks_gctrigger, c->resv_blocks_gctrigger*c->sector_size/1024);
 317        dbg_fsbuild("Blocks required to allow GC merges:   %d (%d KiB)\n",
 318                  c->resv_blocks_gcmerge, c->resv_blocks_gcmerge*c->sector_size/1024);
 319        dbg_fsbuild("Blocks required to GC bad blocks:     %d (%d KiB)\n",
 320                  c->resv_blocks_gcbad, c->resv_blocks_gcbad*c->sector_size/1024);
 321        dbg_fsbuild("Amount of dirty space required to GC: %d bytes\n",
 322                  c->nospc_dirty_size);
 323        dbg_fsbuild("Very dirty blocks before GC triggered: %d\n",
 324                  c->vdirty_blocks_gctrigger);
 325}
 326
 327int jffs2_do_mount_fs(struct jffs2_sb_info *c)
 328{
 329        int ret;
 330        int i;
 331        int size;
 332
 333        c->free_size = c->flash_size;
 334        c->nr_blocks = c->flash_size / c->sector_size;
 335        size = sizeof(struct jffs2_eraseblock) * c->nr_blocks;
 336#ifndef __ECOS
 337        if (jffs2_blocks_use_vmalloc(c))
 338                c->blocks = vmalloc(size);
 339        else
 340#endif
 341                c->blocks = kmalloc(size, GFP_KERNEL);
 342        if (!c->blocks)
 343                return -ENOMEM;
 344
 345        memset(c->blocks, 0, size);
 346        for (i=0; i<c->nr_blocks; i++) {
 347                INIT_LIST_HEAD(&c->blocks[i].list);
 348                c->blocks[i].offset = i * c->sector_size;
 349                c->blocks[i].free_size = c->sector_size;
 350        }
 351
 352        INIT_LIST_HEAD(&c->clean_list);
 353        INIT_LIST_HEAD(&c->very_dirty_list);
 354        INIT_LIST_HEAD(&c->dirty_list);
 355        INIT_LIST_HEAD(&c->erasable_list);
 356        INIT_LIST_HEAD(&c->erasing_list);
 357        INIT_LIST_HEAD(&c->erase_checking_list);
 358        INIT_LIST_HEAD(&c->erase_pending_list);
 359        INIT_LIST_HEAD(&c->erasable_pending_wbuf_list);
 360        INIT_LIST_HEAD(&c->erase_complete_list);
 361        INIT_LIST_HEAD(&c->free_list);
 362        INIT_LIST_HEAD(&c->bad_list);
 363        INIT_LIST_HEAD(&c->bad_used_list);
 364        c->highest_ino = 1;
 365        c->summary = NULL;
 366
 367        ret = jffs2_sum_init(c);
 368        if (ret)
 369                goto out_free;
 370
 371        if (jffs2_build_filesystem(c)) {
 372                dbg_fsbuild("build_fs failed\n");
 373                jffs2_free_ino_caches(c);
 374                jffs2_free_raw_node_refs(c);
 375                ret = -EIO;
 376                goto out_free;
 377        }
 378
 379        jffs2_calc_trigger_levels(c);
 380
 381        return 0;
 382
 383 out_free:
 384#ifndef __ECOS
 385        if (jffs2_blocks_use_vmalloc(c))
 386                vfree(c->blocks);
 387        else
 388#endif
 389                kfree(c->blocks);
 390
 391        return ret;
 392}
 393
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.