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* JFFS2 -- Journalling Flash File System, Version 2.
* Copyright © 2001-2007 Red Hat, Inc.
* Copyright © 2004-2010 David Woodhouse <>
* Created by David Woodhouse <>
* For licensing information, see the file 'LICENCE' in this directory.
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mtd/mtd.h>
#include <linux/mm.h> /* kvfree() */
#include "nodelist.h"
static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *,
struct jffs2_inode_cache *, struct jffs2_full_dirent **);
static inline struct jffs2_inode_cache *
first_inode_chain(int *i, struct jffs2_sb_info *c)
for (; *i < c->inocache_hashsize; (*i)++) {
if (c->inocache_list[*i])
return c->inocache_list[*i];
return NULL;
static inline struct jffs2_inode_cache *
next_inode(int *i, struct jffs2_inode_cache *ic, struct jffs2_sb_info *c)
/* More in this chain? */
if (ic->next)
return ic->next;
return first_inode_chain(i, c);
#define for_each_inode(i, c, ic) \
for (i = 0, ic = first_inode_chain(&i, (c)); \
ic; \
ic = next_inode(&i, ic, (c)))
static void jffs2_build_inode_pass1(struct jffs2_sb_info *c,
struct jffs2_inode_cache *ic,
int *dir_hardlinks)
struct jffs2_full_dirent *fd;
dbg_fsbuild("building directory inode #%u\n", ic->ino);
/* For each child, increase nlink */
for(fd = ic->scan_dents; fd; fd = fd->next) {
struct jffs2_inode_cache *child_ic;
if (!fd->ino)
/* we can get high latency here with huge directories */
child_ic = jffs2_get_ino_cache(c, fd->ino);
if (!child_ic) {
dbg_fsbuild("child \"%s\" (ino #%u) of dir ino #%u doesn't exist!\n",
fd->name, fd->ino, ic->ino);
jffs2_mark_node_obsolete(c, fd->raw);
/* Clear the ic/raw union so it doesn't cause problems later. */
fd->ic = NULL;
/* From this point, fd->raw is no longer used so we can set fd->ic */
fd->ic = child_ic;
/* If we appear (at this stage) to have hard-linked directories,
* set a flag to trigger a scan later */
if (fd->type == DT_DIR) {
child_ic->flags |= INO_FLAGS_IS_DIR;
if (child_ic->pino_nlink > 1)
*dir_hardlinks = 1;
dbg_fsbuild("increased nlink for child \"%s\" (ino #%u)\n", fd->name, fd->ino);
/* Can't free scan_dents so far. We might need them in pass 2 */
/* Scan plan:
- Scan physical nodes. Build map of inodes/dirents. Allocate inocaches as we go
- Scan directory tree from top down, setting nlink in inocaches
- Scan inocaches for inodes with nlink==0
static int jffs2_build_filesystem(struct jffs2_sb_info *c)
int ret, i, dir_hardlinks = 0;
struct jffs2_inode_cache *ic;
struct jffs2_full_dirent *fd;
struct jffs2_full_dirent *dead_fds = NULL;
dbg_fsbuild("build FS data structures\n");
/* First, scan the medium and build all the inode caches with
lists of physical nodes */
ret = jffs2_scan_medium(c);
c->flags &= ~JFFS2_SB_FLAG_SCANNING;
if (ret)
goto exit;
dbg_fsbuild("scanned flash completely\n");
dbg_fsbuild("pass 1 starting\n");
/* Now scan the directory tree, increasing nlink according to every dirent found. */
for_each_inode(i, c, ic) {
if (ic->scan_dents) {
jffs2_build_inode_pass1(c, ic, &dir_hardlinks);
dbg_fsbuild("pass 1 complete\n");
/* Next, scan for inodes with nlink == 0 and remove them. If
they were directories, then decrement the nlink of their
children too, and repeat the scan. As that's going to be
a fairly uncommon occurrence, it's not so evil to do it this
way. Recursion bad. */
dbg_fsbuild("pass 2 starting\n");
for_each_inode(i, c, ic) {
if (ic->pino_nlink)
jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
dbg_fsbuild("pass 2a starting\n");
while (dead_fds) {
fd = dead_fds;
dead_fds = fd->next;
ic = jffs2_get_ino_cache(c, fd->ino);
if (ic)
jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
dbg_fsbuild("pass 2a complete\n");
if (dir_hardlinks) {
/* If we detected directory hardlinks earlier, *hopefully*
* they are gone now because some of the links were from
* dead directories which still had some old dirents lying
* around and not yet garbage-collected, but which have
* been discarded above. So clear the pino_nlink field
* in each directory, so that the final scan below can
* print appropriate warnings. */
for_each_inode(i, c, ic) {
if (ic->flags & INO_FLAGS_IS_DIR)
ic->pino_nlink = 0;
dbg_fsbuild("freeing temporary data structures\n");
/* Finally, we can scan again and free the dirent structs */
for_each_inode(i, c, ic) {
while(ic->scan_dents) {
fd = ic->scan_dents;
ic->scan_dents = fd->next;
/* We do use the pino_nlink field to count nlink of
* directories during fs build, so set it to the
* parent ino# now. Now that there's hopefully only
* one. */
if (fd->type == DT_DIR) {
if (!fd->ic) {
/* We'll have complained about it and marked the coresponding
raw node obsolete already. Just skip it. */
/* We *have* to have set this in jffs2_build_inode_pass1() */
BUG_ON(!(fd->ic->flags & INO_FLAGS_IS_DIR));
/* We clear ic->pino_nlink ∀ directories' ic *only* if dir_hardlinks
* is set. Otherwise, we know this should never trigger anyway, so
* we don't do the check. And ic->pino_nlink still contains the nlink
* value (which is 1). */
if (dir_hardlinks && fd->ic->pino_nlink) {
JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u is also hard linked from dir ino #%u\n",
fd->name, fd->ino, ic->ino, fd->ic->pino_nlink);
/* Should we unlink it from its previous parent? */
/* For directories, ic->pino_nlink holds that parent inode # */
fd->ic->pino_nlink = ic->ino;
ic->scan_dents = NULL;
c->flags &= ~JFFS2_SB_FLAG_BUILDING;
dbg_fsbuild("FS build complete\n");
/* Rotate the lists by some number to ensure wear levelling */
ret = 0;
if (ret) {
for_each_inode(i, c, ic) {
while(ic->scan_dents) {
fd = ic->scan_dents;
ic->scan_dents = fd->next;
return ret;
static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *c,
struct jffs2_inode_cache *ic,
struct jffs2_full_dirent **dead_fds)
struct jffs2_raw_node_ref *raw;
struct jffs2_full_dirent *fd;
dbg_fsbuild("removing ino #%u with nlink == zero.\n", ic->ino);
raw = ic->nodes;
while (raw != (void *)ic) {
struct jffs2_raw_node_ref *next = raw->next_in_ino;
dbg_fsbuild("obsoleting node at 0x%08x\n", ref_offset(raw));
jffs2_mark_node_obsolete(c, raw);
raw = next;
if (ic->scan_dents) {
int whinged = 0;
dbg_fsbuild("inode #%u was a directory which may have children...\n", ic->ino);
while(ic->scan_dents) {
struct jffs2_inode_cache *child_ic;
fd = ic->scan_dents;
ic->scan_dents = fd->next;
if (!fd->ino) {
/* It's a deletion dirent. Ignore it */
dbg_fsbuild("child \"%s\" is a deletion dirent, skipping...\n", fd->name);
if (!whinged)
whinged = 1;
dbg_fsbuild("removing child \"%s\", ino #%u\n", fd->name, fd->ino);
child_ic = jffs2_get_ino_cache(c, fd->ino);
if (!child_ic) {
dbg_fsbuild("cannot remove child \"%s\", ino #%u, because it doesn't exist\n",
fd->name, fd->ino);
/* Reduce nlink of the child. If it's now zero, stick it on the
dead_fds list to be cleaned up later. Else just free the fd */
if (!child_ic->pino_nlink) {
dbg_fsbuild("inode #%u (\"%s\") now has no links; adding to dead_fds list.\n",
fd->ino, fd->name);
fd->next = *dead_fds;
*dead_fds = fd;
} else {
dbg_fsbuild("inode #%u (\"%s\") has now got nlink %d. Ignoring.\n",
fd->ino, fd->name, child_ic->pino_nlink);
We don't delete the inocache from the hash list and free it yet.
The erase code will do that, when all the nodes are completely gone.
static void jffs2_calc_trigger_levels(struct jffs2_sb_info *c)
uint32_t size;
/* Deletion should almost _always_ be allowed. We're fairly
buggered once we stop allowing people to delete stuff
because there's not enough free space... */
c->resv_blocks_deletion = 2;
/* Be conservative about how much space we need before we allow writes.
On top of that which is required for deletia, require an extra 2%
of the medium to be available, for overhead caused by nodes being
split across blocks, etc. */
size = c->flash_size / 50; /* 2% of flash size */
size += c->nr_blocks * 100; /* And 100 bytes per eraseblock */
size += c->sector_size - 1; /* ... and round up */
c->resv_blocks_write = c->resv_blocks_deletion + (size / c->sector_size);
/* When do we let the GC thread run in the background */
c->resv_blocks_gctrigger = c->resv_blocks_write + 1;
/* When do we allow garbage collection to merge nodes to make
long-term progress at the expense of short-term space exhaustion? */
c->resv_blocks_gcmerge = c->resv_blocks_deletion + 1;
/* When do we allow garbage collection to eat from bad blocks rather
than actually making progress? */
c->resv_blocks_gcbad = 0;//c->resv_blocks_deletion + 2;
/* What number of 'very dirty' eraseblocks do we allow before we
trigger the GC thread even if we don't _need_ the space. When we
can't mark nodes obsolete on the medium, the old dirty nodes cause
performance problems because we have to inspect and discard them. */
c->vdirty_blocks_gctrigger = c->resv_blocks_gctrigger;
if (jffs2_can_mark_obsolete(c))
c->vdirty_blocks_gctrigger *= 10;
/* If there's less than this amount of dirty space, don't bother
trying to GC to make more space. It'll be a fruitless task */
c->nospc_dirty_size = c->sector_size + (c->flash_size / 100);
dbg_fsbuild("trigger levels (size %d KiB, block size %d KiB, %d blocks)\n",
c->flash_size / 1024, c->sector_size / 1024, c->nr_blocks);
dbg_fsbuild("Blocks required to allow deletion: %d (%d KiB)\n",
c->resv_blocks_deletion, c->resv_blocks_deletion*c->sector_size/1024);
dbg_fsbuild("Blocks required to allow writes: %d (%d KiB)\n",
c->resv_blocks_write, c->resv_blocks_write*c->sector_size/1024);
dbg_fsbuild("Blocks required to quiesce GC thread: %d (%d KiB)\n",
c->resv_blocks_gctrigger, c->resv_blocks_gctrigger*c->sector_size/1024);
dbg_fsbuild("Blocks required to allow GC merges: %d (%d KiB)\n",
c->resv_blocks_gcmerge, c->resv_blocks_gcmerge*c->sector_size/1024);
dbg_fsbuild("Blocks required to GC bad blocks: %d (%d KiB)\n",
c->resv_blocks_gcbad, c->resv_blocks_gcbad*c->sector_size/1024);
dbg_fsbuild("Amount of dirty space required to GC: %d bytes\n",
dbg_fsbuild("Very dirty blocks before GC triggered: %d\n",
int jffs2_do_mount_fs(struct jffs2_sb_info *c)
int ret;
int i;
int size;
c->free_size = c->flash_size;
c->nr_blocks = c->flash_size / c->sector_size;
size = sizeof(struct jffs2_eraseblock) * c->nr_blocks;
#ifndef __ECOS
if (jffs2_blocks_use_vmalloc(c))
c->blocks = vzalloc(size);
c->blocks = kzalloc(size, GFP_KERNEL);
if (!c->blocks)
return -ENOMEM;
for (i=0; i<c->nr_blocks; i++) {
c->blocks[i].offset = i * c->sector_size;
c->blocks[i].free_size = c->sector_size;
c->highest_ino = 1;
c->summary = NULL;
ret = jffs2_sum_init(c);
if (ret)
goto out_free;
if (jffs2_build_filesystem(c)) {
dbg_fsbuild("build_fs failed\n");
ret = -EIO;
goto out_free;
return 0;
return ret;