fs/jffs2.org/build.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright (C) 2001-2003 Red Hat, Inc.
   5  *
   6  * Created by David Woodhouse <dwmw2@redhat.com>
   7  *
   8  * For licensing information, see the file 'LICENCE' in this directory.
   9  *
  10  * $Id: build.c,v 1.55 2003/10/28 17:02:44 dwmw2 Exp $
  11  *
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/sched.h>
  16 #include <linux/slab.h>
  17 #include "nodelist.h"
  18
  19 static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *, struct jffs2_inode_cache *, struct jffs2_full_dirent **);
  20
  21 static inline struct jffs2_inode_cache *
  22 first_inode_chain(int *i, struct jffs2_sb_info *c)
  23 {
  24         for (; *i < INOCACHE_HASHSIZE; (*i)++) {
  25                 if (c->inocache_list[*i])
  26                         return c->inocache_list[*i];
  27         }
  28         return NULL;
  29 }
  30
  31 static inline struct jffs2_inode_cache *
  32 next_inode(int *i, struct jffs2_inode_cache *ic, struct jffs2_sb_info *c)
  33 {
  34         /* More in this chain? */
  35         if (ic->next)
  36                 return ic->next;
  37         (*i)++;
  38         return first_inode_chain(i, c);
  39 }
  40
  41 #define for_each_inode(i, c, ic)                        \
  42         for (i = 0, ic = first_inode_chain(&i, (c));    \
  43              ic;                                        \
  44              ic = next_inode(&i, ic, (c)))
  45
  46
  47 static inline void jffs2_build_inode_pass1(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
  48 {
  49         struct jffs2_full_dirent *fd;
  50
  51         D1(printk(KERN_DEBUG "jffs2_build_inode building directory inode #%u\n", ic->ino));
  52
  53         /* For each child, increase nlink */
  54         for(fd = ic->scan_dents; fd; fd = fd->next) {
  55                 struct jffs2_inode_cache *child_ic;
  56                 if (!fd->ino)
  57                         continue;
  58
  59                 /* XXX: Can get high latency here with huge directories */
  60
  61                 child_ic = jffs2_get_ino_cache(c, fd->ino);
  62                 if (!child_ic) {
  63                         printk(KERN_NOTICE "Eep. Child \"%s\" (ino #%u) of dir ino #%u doesn't exist!\n",
  64                                   fd->name, fd->ino, ic->ino);
  65                         continue;
  66                 }
  67
  68                 if (child_ic->nlink++ && fd->type == DT_DIR) {
  69                         printk(KERN_NOTICE "Child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n", fd->name, fd->ino, ic->ino);
  70                         if (fd->ino == 1 && ic->ino == 1) {
  71                                 printk(KERN_NOTICE "This is mostly harmless, and probably caused by creating a JFFS2 image\n");
  72                                 printk(KERN_NOTICE "using a buggy version of mkfs.jffs2. Use at least v1.17.\n");
  73                         }
  74                         /* What do we do about it? */
  75                 }
  76                 D1(printk(KERN_DEBUG "Increased nlink for child \"%s\" (ino #%u)\n", fd->name, fd->ino));
  77                 /* Can't free them. We might need them in pass 2 */
  78         }
  79 }
  80
  81 /* Scan plan:
  82  - Scan physical nodes. Build map of inodes/dirents. Allocate inocaches as we go
  83  - Scan directory tree from top down, setting nlink in inocaches
  84  - Scan inocaches for inodes with nlink==0
  85 */
  86 static int jffs2_build_filesystem(struct jffs2_sb_info *c)
  87 {
  88         int ret;
  89         int i;
  90         struct jffs2_inode_cache *ic;
  91         struct jffs2_full_dirent *dead_fds = NULL;
  92
  93         /* First, scan the medium and build all the inode caches with
  94            lists of physical nodes */
  95
  96         c->flags |= JFFS2_SB_FLAG_MOUNTING;
  97         ret = jffs2_scan_medium(c);
  98         c->flags &= ~JFFS2_SB_FLAG_MOUNTING;
  99
 100         if (ret)
 101                 return ret;
 102
 103         D1(printk(KERN_DEBUG "Scanned flash completely\n"));
 104         D1(jffs2_dump_block_lists(c));
 105
 106         /* Now scan the directory tree, increasing nlink according to every dirent found. */
 107         for_each_inode(i, c, ic) {
 108                 D1(printk(KERN_DEBUG "Pass 1: ino #%u\n", ic->ino));
 109
 110                 D1(BUG_ON(ic->ino > c->highest_ino));
 111
 112                 if (ic->scan_dents) {
 113                         jffs2_build_inode_pass1(c, ic);
 114                         cond_resched();
 115                 }
 116         }
 117         D1(printk(KERN_DEBUG "Pass 1 complete\n"));
 118
 119         /* Next, scan for inodes with nlink == 0 and remove them. If
 120            they were directories, then decrement the nlink of their
 121            children too, and repeat the scan. As that's going to be
 122            a fairly uncommon occurrence, it's not so evil to do it this
 123            way. Recursion bad. */
 124         D1(printk(KERN_DEBUG "Pass 2 starting\n"));
 125
 126         for_each_inode(i, c, ic) {
 127                 D1(printk(KERN_DEBUG "Pass 2: ino #%u, nlink %d, ic %p, nodes %p\n", ic->ino, ic->nlink, ic, ic->nodes));
 128                 if (ic->nlink)
 129                         continue;
 130
 131                 jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
 132                 cond_resched();
 133         }
 134
 135         D1(printk(KERN_DEBUG "Pass 2a starting\n"));
 136
 137         while (dead_fds) {
 138                 struct jffs2_inode_cache *ic;
 139                 struct jffs2_full_dirent *fd = dead_fds;
 140
 141                 dead_fds = fd->next;
 142
 143                 ic = jffs2_get_ino_cache(c, fd->ino);
 144                 D1(printk(KERN_DEBUG "Removing dead_fd ino #%u (\"%s\"), ic at %p\n", fd->ino, fd->name, ic));
 145
 146                 if (ic)
 147                         jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
 148                 jffs2_free_full_dirent(fd);
 149         }
 150
 151         D1(printk(KERN_DEBUG "Pass 2 complete\n"));
 152
 153         /* Finally, we can scan again and free the dirent structs */
 154         for_each_inode(i, c, ic) {
 155                 struct jffs2_full_dirent *fd;
 156                 D1(printk(KERN_DEBUG "Pass 3: ino #%u, ic %p, nodes %p\n", ic->ino, ic, ic->nodes));
 157
 158                 while(ic->scan_dents) {
 159                         fd = ic->scan_dents;
 160                         ic->scan_dents = fd->next;
 161                         jffs2_free_full_dirent(fd);
 162                 }
 163                 ic->scan_dents = NULL;
 164                 cond_resched();
 165         }
 166         D1(printk(KERN_DEBUG "Pass 3 complete\n"));
 167         D1(jffs2_dump_block_lists(c));
 168
 169         /* Rotate the lists by some number to ensure wear levelling */
 170         jffs2_rotate_lists(c);
 171
 172         return ret;
 173 }
 174
 175 static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic, struct jffs2_full_dirent **dead_fds)
 176 {
 177         struct jffs2_raw_node_ref *raw;
 178         struct jffs2_full_dirent *fd;
 179
 180         D1(printk(KERN_DEBUG "JFFS2: Removing ino #%u with nlink == zero.\n", ic->ino));
 181
 182         for (raw = ic->nodes; raw != (void *)ic; raw = raw->next_in_ino) {
 183                 D1(printk(KERN_DEBUG "obsoleting node at 0x%08x\n", ref_offset(raw)));
 184                 jffs2_mark_node_obsolete(c, raw);
 185         }
 186
 187         if (ic->scan_dents) {
 188                 int whinged = 0;
 189                 D1(printk(KERN_DEBUG "Inode #%u was a directory which may have children...\n", ic->ino));
 190
 191                 while(ic->scan_dents) {
 192                         struct jffs2_inode_cache *child_ic;
 193
 194                         fd = ic->scan_dents;
 195                         ic->scan_dents = fd->next;
 196
 197                         if (!fd->ino) {
 198                                 /* It's a deletion dirent. Ignore it */
 199                                 D1(printk(KERN_DEBUG "Child \"%s\" is a deletion dirent, skipping...\n", fd->name));
 200                                 jffs2_free_full_dirent(fd);
 201                                 continue;
 202                         }
 203                         if (!whinged) {
 204                                 whinged = 1;
 205                                 printk(KERN_NOTICE "Inode #%u was a directory with children - removing those too...\n", ic->ino);
 206                         }
 207
 208                         D1(printk(KERN_DEBUG "Removing child \"%s\", ino #%u\n",
 209                                   fd->name, fd->ino));
 210
 211                         child_ic = jffs2_get_ino_cache(c, fd->ino);
 212                         if (!child_ic) {
 213                                 printk(KERN_NOTICE "Cannot remove child \"%s\", ino #%u, because it doesn't exist\n", fd->name, fd->ino);
 214                                 jffs2_free_full_dirent(fd);
 215                                 continue;
 216                         }
 217
 218                         /* Reduce nlink of the child. If it's now zero, stick it on the
 219                            dead_fds list to be cleaned up later. Else just free the fd */
 220
 221                         child_ic->nlink--;
 222
 223                         if (!child_ic->nlink) {
 224                                 D1(printk(KERN_DEBUG "Inode #%u (\"%s\") has now got zero nlink. Adding to dead_fds list.\n",
 225                                           fd->ino, fd->name));
 226                                 fd->next = *dead_fds;
 227                                 *dead_fds = fd;
 228                         } else {
 229                                 D1(printk(KERN_DEBUG "Inode #%u (\"%s\") has now got nlink %d. Ignoring.\n",
 230                                           fd->ino, fd->name, child_ic->nlink));
 231                                 jffs2_free_full_dirent(fd);
 232                         }
 233                 }
 234         }
 235
 236         /*
 237            We don't delete the inocache from the hash list and free it yet.
 238            The erase code will do that, when all the nodes are completely gone.
 239         */
 240 }
 241
 242 static void jffs2_calc_trigger_levels(struct jffs2_sb_info *c)
 243 {
 244         uint32_t size;
 245
 246         /* Deletion should almost _always_ be allowed. We're fairly
 247            buggered once we stop allowing people to delete stuff
 248            because there's not enough free space... */
 249         c->resv_blocks_deletion = 2;
 250
 251         /* Be conservative about how much space we need before we allow writes.
 252            On top of that which is required for deletia, require an extra 2%
 253            of the medium to be available, for overhead caused by nodes being
 254            split across blocks, etc. */
 255
 256         size = c->flash_size / 50; /* 2% of flash size */
 257         size += c->nr_blocks * 100; /* And 100 bytes per eraseblock */
 258         size += c->sector_size - 1; /* ... and round up */
 259
 260         c->resv_blocks_write = c->resv_blocks_deletion + (size / c->sector_size);
 261
 262         /* When do we let the GC thread run in the background */
 263
 264         c->resv_blocks_gctrigger = c->resv_blocks_write + 1;
 265
 266         /* When do we allow garbage collection to merge nodes to make
 267            long-term progress at the expense of short-term space exhaustion? */
 268         c->resv_blocks_gcmerge = c->resv_blocks_deletion + 1;
 269
 270         /* When do we allow garbage collection to eat from bad blocks rather
 271            than actually making progress? */
 272         c->resv_blocks_gcbad = 0;//c->resv_blocks_deletion + 2;
 273
 274         /* If there's less than this amount of dirty space, don't bother
 275            trying to GC to make more space. It'll be a fruitless task */
 276         c->nospc_dirty_size = c->sector_size + (c->flash_size / 100);
 277
 278         D1(printk(KERN_DEBUG "JFFS2 trigger levels (size %d KiB, block size %d KiB, %d blocks)\n",
 279                   c->flash_size / 1024, c->sector_size / 1024, c->nr_blocks));
 280         D1(printk(KERN_DEBUG "Blocks required to allow deletion:    %d (%d KiB)\n",
 281                   c->resv_blocks_deletion, c->resv_blocks_deletion*c->sector_size/1024));
 282         D1(printk(KERN_DEBUG "Blocks required to allow writes:      %d (%d KiB)\n",
 283                   c->resv_blocks_write, c->resv_blocks_write*c->sector_size/1024));
 284         D1(printk(KERN_DEBUG "Blocks required to quiesce GC thread: %d (%d KiB)\n",
 285                   c->resv_blocks_gctrigger, c->resv_blocks_gctrigger*c->sector_size/1024));
 286         D1(printk(KERN_DEBUG "Blocks required to allow GC merges:   %d (%d KiB)\n",
 287                   c->resv_blocks_gcmerge, c->resv_blocks_gcmerge*c->sector_size/1024));
 288         D1(printk(KERN_DEBUG "Blocks required to GC bad blocks:     %d (%d KiB)\n",
 289                   c->resv_blocks_gcbad, c->resv_blocks_gcbad*c->sector_size/1024));
 290         D1(printk(KERN_DEBUG "Amount of dirty space required to GC: %d bytes\n",
 291                   c->nospc_dirty_size));
 292 }
 293
 294 int jffs2_do_mount_fs(struct jffs2_sb_info *c)
 295 {
 296         int i;
 297
 298         c->free_size = c->flash_size;
 299         c->nr_blocks = c->flash_size / c->sector_size;
 300         c->blocks = kmalloc(sizeof(struct jffs2_eraseblock) * c->nr_blocks, GFP_KERNEL);
 301         if (!c->blocks)
 302                 return -ENOMEM;
 303         for (i=0; i<c->nr_blocks; i++) {
 304                 INIT_LIST_HEAD(&c->blocks[i].list);
 305                 c->blocks[i].offset = i * c->sector_size;
 306                 c->blocks[i].free_size = c->sector_size;
 307                 c->blocks[i].dirty_size = 0;
 308                 c->blocks[i].wasted_size = 0;
 309                 c->blocks[i].unchecked_size = 0;
 310                 c->blocks[i].used_size = 0;
 311                 c->blocks[i].first_node = NULL;
 312                 c->blocks[i].last_node = NULL;
 313         }
 314
 315         init_MUTEX(&c->alloc_sem);
 316         init_MUTEX(&c->erase_free_sem);
 317         init_waitqueue_head(&c->erase_wait);
 318         init_waitqueue_head(&c->inocache_wq);
 319         spin_lock_init(&c->erase_completion_lock);
 320         spin_lock_init(&c->inocache_lock);
 321
 322         INIT_LIST_HEAD(&c->clean_list);
 323         INIT_LIST_HEAD(&c->very_dirty_list);
 324         INIT_LIST_HEAD(&c->dirty_list);
 325         INIT_LIST_HEAD(&c->erasable_list);
 326         INIT_LIST_HEAD(&c->erasing_list);
 327         INIT_LIST_HEAD(&c->erase_pending_list);
 328         INIT_LIST_HEAD(&c->erasable_pending_wbuf_list);
 329         INIT_LIST_HEAD(&c->erase_complete_list);
 330         INIT_LIST_HEAD(&c->free_list);
 331         INIT_LIST_HEAD(&c->bad_list);
 332         INIT_LIST_HEAD(&c->bad_used_list);
 333         c->highest_ino = 1;
 334
 335         if (jffs2_build_filesystem(c)) {
 336                 D1(printk(KERN_DEBUG "build_fs failed\n"));
 337                 jffs2_free_ino_caches(c);
 338                 jffs2_free_raw_node_refs(c);
 339                 kfree(c->blocks);
 340                 return -EIO;
 341         }
 342
 343         jffs2_calc_trigger_levels(c);
 344
 345         return 0;
 346 }