fs/jffs2/build.c - kernel/common - Git at Google

 /*
  * JFFS2 -- Journalling Flash File System, Version 2.
  *
  * Copyright © 2001-2007 Red Hat, Inc.
  * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
  *
  * Created by David Woodhouse <dwmw2@infradead.org>
  *
  * 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 "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;
 	(*i)++;
 	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)
 			continue;

 		/* 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;
 			continue;
 		}

 		/* From this point, fd->raw is no longer used so we can set fd->ic */
 		fd->ic = child_ic;
 		child_ic->pino_nlink++;
 		/* 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 */

 	c->flags |= JFFS2_SB_FLAG_SCANNING;
 	ret = jffs2_scan_medium(c);
 	c->flags &= ~JFFS2_SB_FLAG_SCANNING;
 	if (ret)
 		goto exit;

 	dbg_fsbuild("scanned flash completely\n");
 	jffs2_dbg_dump_block_lists_nolock(c);

 	dbg_fsbuild("pass 1 starting\n");
 	c->flags |= JFFS2_SB_FLAG_BUILDING;
 	/* 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);
 			cond_resched();
 		}
 	}

 	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)
 			continue;

 		jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
 		cond_resched();
 	}

 	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);
 		jffs2_free_full_dirent(fd);
 	}

 	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. */
 					continue;
 				}

 				/* 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;
 			}
 			jffs2_free_full_dirent(fd);
 		}
 		ic->scan_dents = NULL;
 		cond_resched();
 	}
 	jffs2_build_xattr_subsystem(c);
 	c->flags &= ~JFFS2_SB_FLAG_BUILDING;

 	dbg_fsbuild("FS build complete\n");

 	/* Rotate the lists by some number to ensure wear levelling */
 	jffs2_rotate_lists(c);

 	ret = 0;

 exit:
 	if (ret) {
 		for_each_inode(i, c, ic) {
 			while(ic->scan_dents) {
 				fd = ic->scan_dents;
 				ic->scan_dents = fd->next;
 				jffs2_free_full_dirent(fd);
 			}
 		}
 		jffs2_clear_xattr_subsystem(c);
 	}

 	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);
 				jffs2_free_full_dirent(fd);
 				continue;
 			}
 			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);
 				jffs2_free_full_dirent(fd);
 				continue;
 			}

 			/* 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 */
 			child_ic->pino_nlink--;

 			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);
 				jffs2_free_full_dirent(fd);
 			}
 		}
 	}

 	/*
 	   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",
 		  c->nospc_dirty_size);
 	dbg_fsbuild("Very dirty blocks before GC triggered: %d\n",
 		  c->vdirty_blocks_gctrigger);
 }

 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);
 	else
 #endif
 		c->blocks = kzalloc(size, GFP_KERNEL);
 	if (!c->blocks)
 		return -ENOMEM;

 	for (i=0; i<c->nr_blocks; i++) {
 		INIT_LIST_HEAD(&c->blocks[i].list);
 		c->blocks[i].offset = i * c->sector_size;
 		c->blocks[i].free_size = c->sector_size;
 	}

 	INIT_LIST_HEAD(&c->clean_list);
 	INIT_LIST_HEAD(&c->very_dirty_list);
 	INIT_LIST_HEAD(&c->dirty_list);
 	INIT_LIST_HEAD(&c->erasable_list);
 	INIT_LIST_HEAD(&c->erasing_list);
 	INIT_LIST_HEAD(&c->erase_checking_list);
 	INIT_LIST_HEAD(&c->erase_pending_list);
 	INIT_LIST_HEAD(&c->erasable_pending_wbuf_list);
 	INIT_LIST_HEAD(&c->erase_complete_list);
 	INIT_LIST_HEAD(&c->free_list);
 	INIT_LIST_HEAD(&c->bad_list);
 	INIT_LIST_HEAD(&c->bad_used_list);
 	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");
 		jffs2_free_ino_caches(c);
 		jffs2_free_raw_node_refs(c);
 		ret = -EIO;
 		goto out_free;
 	}

 	jffs2_calc_trigger_levels(c);

 	return 0;

  out_free:
 #ifndef __ECOS
 	if (jffs2_blocks_use_vmalloc(c))
 		vfree(c->blocks);
 	else
 #endif
 		kfree(c->blocks);

 	return ret;
 }
	/*
	* JFFS2 -- Journalling Flash File System, Version 2.
	*
	* Copyright © 2001-2007 Red Hat, Inc.
	* Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
	*
	* Created by David Woodhouse <dwmw2@infradead.org>
	*
	* 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 "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;
	(*i)++;
	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)
	continue;

	/* 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;
	continue;
	}

	/* From this point, fd->raw is no longer used so we can set fd->ic */
	fd->ic = child_ic;
	child_ic->pino_nlink++;
	/* 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 */

	c->flags \|= JFFS2_SB_FLAG_SCANNING;
	ret = jffs2_scan_medium(c);
	c->flags &= ~JFFS2_SB_FLAG_SCANNING;
	if (ret)
	goto exit;

	dbg_fsbuild("scanned flash completely\n");
	jffs2_dbg_dump_block_lists_nolock(c);

	dbg_fsbuild("pass 1 starting\n");
	c->flags \|= JFFS2_SB_FLAG_BUILDING;
	/* 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);
	cond_resched();
	}
	}

	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)
	continue;

	jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
	cond_resched();
	}

	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);
	jffs2_free_full_dirent(fd);
	}

	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. */
	continue;
	}

	/* 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;
	}
	jffs2_free_full_dirent(fd);
	}
	ic->scan_dents = NULL;
	cond_resched();
	}
	jffs2_build_xattr_subsystem(c);
	c->flags &= ~JFFS2_SB_FLAG_BUILDING;

	dbg_fsbuild("FS build complete\n");

	/* Rotate the lists by some number to ensure wear levelling */
	jffs2_rotate_lists(c);

	ret = 0;

	exit:
	if (ret) {
	for_each_inode(i, c, ic) {
	while(ic->scan_dents) {
	fd = ic->scan_dents;
	ic->scan_dents = fd->next;
	jffs2_free_full_dirent(fd);
	}
	}
	jffs2_clear_xattr_subsystem(c);
	}

	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);
	jffs2_free_full_dirent(fd);
	continue;
	}
	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);
	jffs2_free_full_dirent(fd);
	continue;
	}

	/* 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 */
	child_ic->pino_nlink--;

	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);
	jffs2_free_full_dirent(fd);
	}
	}
	}

	/*
	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",
	c->nospc_dirty_size);
	dbg_fsbuild("Very dirty blocks before GC triggered: %d\n",
	c->vdirty_blocks_gctrigger);
	}

	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);
	else
	#endif
	c->blocks = kzalloc(size, GFP_KERNEL);
	if (!c->blocks)
	return -ENOMEM;

	for (i=0; i<c->nr_blocks; i++) {
	INIT_LIST_HEAD(&c->blocks[i].list);
	c->blocks[i].offset = i * c->sector_size;
	c->blocks[i].free_size = c->sector_size;
	}

	INIT_LIST_HEAD(&c->clean_list);
	INIT_LIST_HEAD(&c->very_dirty_list);
	INIT_LIST_HEAD(&c->dirty_list);
	INIT_LIST_HEAD(&c->erasable_list);
	INIT_LIST_HEAD(&c->erasing_list);
	INIT_LIST_HEAD(&c->erase_checking_list);
	INIT_LIST_HEAD(&c->erase_pending_list);
	INIT_LIST_HEAD(&c->erasable_pending_wbuf_list);
	INIT_LIST_HEAD(&c->erase_complete_list);
	INIT_LIST_HEAD(&c->free_list);
	INIT_LIST_HEAD(&c->bad_list);
	INIT_LIST_HEAD(&c->bad_used_list);
	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");
	jffs2_free_ino_caches(c);
	jffs2_free_raw_node_refs(c);
	ret = -EIO;
	goto out_free;
	}

	jffs2_calc_trigger_levels(c);

	return 0;

	out_free:
	#ifndef __ECOS
	if (jffs2_blocks_use_vmalloc(c))
	vfree(c->blocks);
	else
	#endif
	kfree(c->blocks);

	return ret;
	}