/*
   * 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 <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;
  	(*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
  ", 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!
  ",

  				  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)
  ", 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
  ");

  	/* 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
  ");

  	jffs2_dbg_dump_block_lists_nolock(c);

  	dbg_fsbuild("pass 1 starting
  ");

  	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
  ");

  
  	/* 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
  ");

  
  	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
  ");

  
  	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
  ");

  
  	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
  ");

  	/* 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
  ",
  						    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
  ");

  
  	/* 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.
  ", 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
  ", 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...
  ", 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...
  ", fd->name);

  				jffs2_free_full_dirent(fd);
  				continue;
  			}

  			if (!whinged)

  				whinged = 1;

  			dbg_fsbuild("removing child \"%s\", ino #%u
  ", 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
  ",
  						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.
  ",

  					  fd->ino, fd->name);

  				fd->next = *dead_fds;
  				*dead_fds = fd;
  			} else {

  				dbg_fsbuild("inode #%u (\"%s\") has now got nlink %d. Ignoring.
  ",

  					  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)
  ",
  		    c->flash_size / 1024, c->sector_size / 1024, c->nr_blocks);

  	dbg_fsbuild("Blocks required to allow deletion:    %d (%d KiB)
  ",
  		  c->resv_blocks_deletion, c->resv_blocks_deletion*c->sector_size/1024);
  	dbg_fsbuild("Blocks required to allow writes:      %d (%d KiB)
  ",
  		  c->resv_blocks_write, c->resv_blocks_write*c->sector_size/1024);
  	dbg_fsbuild("Blocks required to quiesce GC thread: %d (%d KiB)
  ",
  		  c->resv_blocks_gctrigger, c->resv_blocks_gctrigger*c->sector_size/1024);
  	dbg_fsbuild("Blocks required to allow GC merges:   %d (%d KiB)
  ",
  		  c->resv_blocks_gcmerge, c->resv_blocks_gcmerge*c->sector_size/1024);
  	dbg_fsbuild("Blocks required to GC bad blocks:     %d (%d KiB)
  ",
  		  c->resv_blocks_gcbad, c->resv_blocks_gcbad*c->sector_size/1024);
  	dbg_fsbuild("Amount of dirty space required to GC: %d bytes
  ",
  		  c->nospc_dirty_size);

  	dbg_fsbuild("Very dirty blocks before GC triggered: %d
  ",
  		  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
  ");

  		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:

  	kvfree(c->blocks);

  
  	return ret;

  }