Patchwork [09/10] UBI: Add fastmap core

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Submitter Richard Weinberger
Date Sept. 24, 2012, 6:31 p.m.
Message ID <1348511492-91606-10-git-send-email-richard@nod.at>
Download mbox | patch
Permalink /patch/186506/
State New
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Richard Weinberger - Sept. 24, 2012, 6:31 p.m.
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 drivers/mtd/ubi/fastmap.c | 1560 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 1560 insertions(+), 0 deletions(-)
 create mode 100644 drivers/mtd/ubi/fastmap.c

Patch

diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
new file mode 100644
index 0000000..be73a1d
--- /dev/null
+++ b/drivers/mtd/ubi/fastmap.c
@@ -0,0 +1,1560 @@ 
+/*
+ * Copyright (c) 2012 Linutronix GmbH
+ * Author: Richard Weinberger <richard@nod.at>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
+ * the GNU General Public License for more details.
+ *
+ */
+
+#include <linux/crc32.h>
+#include "ubi.h"
+
+/**
+ * ubi_calc_fm_size - calculates the fastmap size in bytes for an UBI device.
+ * @ubi: UBI device description object
+ */
+size_t ubi_calc_fm_size(struct ubi_device *ubi)
+{
+	size_t size;
+
+	size = sizeof(struct ubi_fm_hdr) + \
+		sizeof(struct ubi_fm_scan_pool) + \
+		sizeof(struct ubi_fm_scan_pool) + \
+		(ubi->peb_count * sizeof(struct ubi_fm_ec)) + \
+		(sizeof(struct ubi_fm_eba) + \
+		(ubi->peb_count * sizeof(__be32))) + \
+		sizeof(struct ubi_fm_volhdr) * UBI_MAX_VOLUMES;
+	return roundup(size, ubi->leb_size);
+}
+
+
+/**
+ * new_fm_vhdr - allocate a new volume header for fastmap usage.
+ * @ubi: UBI device description object
+ * @vol_id: the VID of the new header
+ *
+ * Returns a new struct ubi_vid_hdr on success.
+ * NULL indicates out of memory.
+ */
+static struct ubi_vid_hdr *new_fm_vhdr(struct ubi_device *ubi, int vol_id)
+{
+	struct ubi_vid_hdr *new;
+
+	new = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+	if (!new)
+		goto out;
+
+	new->vol_type = UBI_VID_DYNAMIC;
+	new->vol_id = cpu_to_be32(vol_id);
+
+	/* UBI implementations without fastmap support have to delete the
+	 * fastmap.
+	 */
+	new->compat = UBI_COMPAT_DELETE;
+
+out:
+	return new;
+}
+
+/**
+ * add_aeb - create and add a attach erase block to a given list.
+ * @ai: UBI attach info object
+ * @list: the target list
+ * @pnum: PEB number of the new attach erase block
+ * @ec: erease counter of the new LEB
+ * @scrub: scrub this PEB after attaching
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int add_aeb(struct ubi_attach_info *ai, struct list_head *list,
+		   int pnum, int ec, int scrub)
+{
+	struct ubi_ainf_peb *aeb;
+
+	aeb = kmem_cache_alloc(ai->aeb_slab_cache, GFP_KERNEL);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->pnum = pnum;
+	aeb->ec = ec;
+	aeb->lnum = -1;
+	aeb->scrub = scrub;
+	aeb->copy_flag = aeb->sqnum = 0;
+
+	ai->ec_sum += aeb->ec;
+	ai->ec_count++;
+
+	if (ai->max_ec < aeb->ec)
+		ai->max_ec = aeb->ec;
+
+	if (ai->min_ec > aeb->ec)
+		ai->min_ec = aeb->ec;
+
+	list_add_tail(&aeb->u.list, list);
+
+	return 0;
+}
+
+/**
+ * add_vol - create and add a new volume to ubi_attach_info.
+ * @ai: ubi_attach_info object
+ * @vol_id: VID of the new volume
+ * @used_ebs: number of used EBS
+ * @data_pad: data padding value of the new volume
+ * @vol_type: volume type
+ * @last_eb_bytes: number of bytes in the last LEB
+ *
+ * Returns the new struct ubi_ainf_volume on success.
+ * NULL indicates an error.
+ */
+static struct ubi_ainf_volume *add_vol(struct ubi_attach_info *ai, int vol_id,
+				       int used_ebs, int data_pad, u8 vol_type,
+				       int last_eb_bytes)
+{
+	struct ubi_ainf_volume *av;
+	struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;
+
+	while (*p) {
+		parent = *p;
+		av = rb_entry(parent, struct ubi_ainf_volume, rb);
+
+		if (vol_id > av->vol_id)
+			p = &(*p)->rb_left;
+		else if (vol_id > av->vol_id)
+			p = &(*p)->rb_right;
+	}
+
+	av = kmalloc(sizeof(struct ubi_ainf_volume), GFP_KERNEL);
+	if (!av)
+		goto out;
+
+	av->highest_lnum = av->leb_count = 0;
+	av->vol_id = vol_id;
+	av->used_ebs = used_ebs;
+	av->data_pad = data_pad;
+	av->last_data_size = last_eb_bytes;
+	av->compat = 0;
+	av->vol_type = vol_type;
+	av->root = RB_ROOT;
+
+	dbg_bld("found volume (ID %i)", vol_id);
+
+	rb_link_node(&av->rb, parent, p);
+	rb_insert_color(&av->rb, &ai->volumes);
+
+out:
+	return av;
+}
+
+/**
+ * assign_aeb_to_av - assigns a SEB to a given ainf_volume and removes it
+ * from it's original list.
+ * @ai: ubi_attach_info object
+ * @aeb: the to be assigned SEB
+ * @av: target scan volume
+ */
+static void assign_aeb_to_av(struct ubi_attach_info *ai,
+			     struct ubi_ainf_peb *aeb,
+			     struct ubi_ainf_volume *av)
+{
+	struct ubi_ainf_peb *tmp_aeb;
+	struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;
+
+	p = &av->root.rb_node;
+	while (*p) {
+		parent = *p;
+
+		tmp_aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
+		if (aeb->lnum != tmp_aeb->lnum) {
+			if (aeb->lnum < tmp_aeb->lnum)
+				p = &(*p)->rb_left;
+			else
+				p = &(*p)->rb_right;
+
+			continue;
+		} else
+			break;
+	}
+
+	list_del(&aeb->u.list);
+	av->leb_count++;
+
+	rb_link_node(&aeb->u.rb, parent, p);
+	rb_insert_color(&aeb->u.rb, &av->root);
+}
+
+/**
+ * update_vol - inserts or updates a LEB which was found a pool.
+ * @ubi: the UBI device object
+ * @ai: attach info object
+ * @av: the volume this LEB belongs to
+ * @new_vh: the volume header derived from new_aeb
+ * @new_aeb: the AEB to be examined
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int update_vol(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		      struct ubi_ainf_volume *av, struct ubi_vid_hdr *new_vh,
+		      struct ubi_ainf_peb *new_aeb)
+{
+	struct rb_node **p = &av->root.rb_node, *parent = NULL;
+	struct ubi_ainf_peb *aeb, *victim;
+	int cmp_res;
+
+	while (*p) {
+		parent = *p;
+		aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
+
+		if (be32_to_cpu(new_vh->lnum) != aeb->lnum) {
+			if (be32_to_cpu(new_vh->lnum) < aeb->lnum)
+				p = &(*p)->rb_left;
+			else
+				p = &(*p)->rb_right;
+
+			continue;
+		}
+
+		/* This case can happen if the fastmap gets written
+		 * because of a volume change (creation, deletion, ..).
+		 * Then a PEB can be within the persistent EBA and the pool.
+		 */
+		if (aeb->pnum == new_aeb->pnum) {
+			ubi_assert(aeb->lnum == new_aeb->lnum);
+			kmem_cache_free(ai->aeb_slab_cache, new_aeb);
+
+			return 0;
+		}
+
+		cmp_res = ubi_compare_lebs(ubi, aeb, new_aeb->pnum, new_vh);
+		if (cmp_res < 0)
+			return cmp_res;
+
+		/* new_aeb is newer */
+		if (cmp_res & 1) {
+			victim = kmem_cache_alloc(ai->aeb_slab_cache,
+				GFP_KERNEL);
+			if (!victim)
+				return -ENOMEM;
+
+			victim->ec = aeb->ec;
+			victim->pnum = aeb->pnum;
+			list_add_tail(&victim->u.list, &ai->erase);
+
+			if (av->highest_lnum == be32_to_cpu(new_vh->lnum))
+				av->last_data_size = \
+					be32_to_cpu(new_vh->data_size);
+
+			dbg_bld("vol %i: AEB %i's PEB %i is the newer",
+				av->vol_id, aeb->lnum, new_aeb->pnum);
+
+			aeb->ec = new_aeb->ec;
+			aeb->pnum = new_aeb->pnum;
+			aeb->copy_flag = new_vh->copy_flag;
+			aeb->scrub = new_aeb->scrub;
+			kmem_cache_free(ai->aeb_slab_cache, new_aeb);
+
+		/* new_aeb is older */
+		} else {
+			dbg_bld("vol %i: AEB %i's PEB %i is old, dropping it",
+				av->vol_id, aeb->lnum, new_aeb->pnum);
+			list_add_tail(&new_aeb->u.list, &ai->erase);
+		}
+
+		return 0;
+	}
+	/* This LEB is new, let's add it to the volume */
+
+	if (av->highest_lnum <= be32_to_cpu(new_vh->lnum)) {
+		av->highest_lnum = be32_to_cpu(new_vh->lnum);
+		av->last_data_size = be32_to_cpu(new_vh->data_size);
+	}
+
+	if (av->vol_type == UBI_STATIC_VOLUME)
+		av->used_ebs = be32_to_cpu(new_vh->used_ebs);
+
+	av->leb_count++;
+
+	rb_link_node(&new_aeb->u.rb, parent, p);
+	rb_insert_color(&new_aeb->u.rb, &av->root);
+
+	return 0;
+}
+
+/**
+ * process_pool_aeb - we found a non-empty PEB in a pool.
+ * @ubi: UBI device object
+ * @ai: attach info object
+ * @new_vh: the volume header derived from new_aeb
+ * @new_aeb: the AEB to be examined
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int process_pool_aeb(struct ubi_device *ubi, struct ubi_attach_info *ai,
+			    struct ubi_vid_hdr *new_vh,
+			    struct ubi_ainf_peb *new_aeb)
+{
+	struct ubi_ainf_volume *av, *tmp_av = NULL;
+	struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;
+	int found = 0;
+
+	if (be32_to_cpu(new_vh->vol_id) == UBI_FM_SB_VOLUME_ID ||
+		be32_to_cpu(new_vh->vol_id) == UBI_FM_DATA_VOLUME_ID) {
+		kmem_cache_free(ai->aeb_slab_cache, new_aeb);
+
+		return 0;
+	}
+
+	/* Find the volume this SEB belongs to */
+	while (*p) {
+		parent = *p;
+		tmp_av = rb_entry(parent, struct ubi_ainf_volume, rb);
+
+		if (be32_to_cpu(new_vh->vol_id) > tmp_av->vol_id)
+			p = &(*p)->rb_left;
+		else if (be32_to_cpu(new_vh->vol_id) < tmp_av->vol_id)
+			p = &(*p)->rb_right;
+		else {
+			found = 1;
+			break;
+		}
+	}
+
+	if (found)
+		av = tmp_av;
+	else {
+		ubi_err("orphaned volume in fastmap pool!");
+		return UBI_BAD_FASTMAP;
+	}
+
+	ubi_assert(be32_to_cpu(new_vh->vol_id) == av->vol_id);
+
+	return update_vol(ubi, ai, av, new_vh, new_aeb);
+}
+
+/**
+ * unmap_peb - unmap a PEB.
+ * If fastmap detects a free PEB in the pool it has to check whether
+ * this PEB has been unmapped after writing the fastmap.
+ *
+ * @ai: UBI attach info object
+ * @pnum: The PEB to be unmapped
+ */
+static void unmap_peb(struct ubi_attach_info *ai, int pnum)
+{
+	struct ubi_ainf_volume *av;
+	struct rb_node *node, *node2;
+	struct ubi_ainf_peb *aeb;
+
+	for (node = rb_first(&ai->volumes); node; node = rb_next(node)) {
+		av = rb_entry(node, struct ubi_ainf_volume, rb);
+
+		for (node2 = rb_first(&av->root); node2;
+		     node2 = rb_next(node2)) {
+			aeb = rb_entry(node2, struct ubi_ainf_peb, u.rb);
+			if (aeb->pnum == pnum) {
+				rb_erase(&aeb->u.rb, &av->root);
+				kmem_cache_free(ai->aeb_slab_cache, aeb);
+				return;
+			}
+		}
+	}
+}
+
+/**
+ * scan_pool - scans a pool for changed (no longer empty PEBs).
+ * @ubi: UBI device object
+ * @ai: attach info object
+ * @pebs: an array of all PEB numbers in the to be scanned pool
+ * @pool_size: size of the pool (number of entries in @pebs)
+ * @max_sqnum: pointer to the maximal sequence number
+ * @eba_orphans: list of PEBs which need to be scanned
+ * @free: list of PEBs which are most likely free (and go into @ai->free)
+ *
+ * Returns 0 on success, if the pool is unusable UBI_BAD_FASTMAP is returned.
+ * < 0 indicates an internal error.
+ */
+static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		     int *pebs, int pool_size, unsigned long long *max_sqnum,
+		     struct list_head *eba_orphans, struct list_head *free)
+{
+	struct ubi_vid_hdr *vh;
+	struct ubi_ec_hdr *ech;
+	struct ubi_ainf_peb *new_aeb, *tmp_aeb;
+	int i, pnum, err, found_orphan, ret = 0;
+
+	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ech)
+		return -ENOMEM;
+
+	vh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+	if (!vh) {
+		kfree(ech);
+		return -ENOMEM;
+	}
+
+	dbg_bld("scanning fastmap pool: size = %i", pool_size);
+
+	/*
+	 * Now scan all PEBs in the pool to find changes which have been made
+	 * after the creation of the fastmap
+	 */
+	for (i = 0; i < pool_size; i++) {
+		int scrub = 0;
+
+		pnum = be32_to_cpu(pebs[i]);
+
+		if (ubi_io_is_bad(ubi, pnum)) {
+			ubi_err("bad PEB in fastmap pool!");
+			ret = UBI_BAD_FASTMAP;
+			goto out;
+		}
+
+		err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+		if (err && err != UBI_IO_BITFLIPS) {
+			ubi_err("unable to read EC header! PEB:%i err:%i",
+				pnum, err);
+			ret = err > 0 ? UBI_BAD_FASTMAP : err;
+			goto out;
+		} else if (ret == UBI_IO_BITFLIPS)
+			scrub = 1;
+
+		if (be32_to_cpu(ech->image_seq) != ubi->image_seq) {
+			ubi_err("bad image seq: 0x%x, expected: 0x%x",
+				be32_to_cpu(ech->image_seq), ubi->image_seq);
+			err = UBI_BAD_FASTMAP;
+			goto out;
+		}
+
+		err = ubi_io_read_vid_hdr(ubi, pnum, vh, 0);
+		if (err == UBI_IO_FF || err == UBI_IO_FF_BITFLIPS) {
+			unsigned long long ec = be64_to_cpu(ech->ec);
+			unmap_peb(ai, pnum);
+			dbg_bld("Adding PEB to free: %i", pnum);
+			if (err == UBI_IO_FF_BITFLIPS)
+				add_aeb(ai, free, pnum, ec, 1);
+			else
+				add_aeb(ai, free, pnum, ec, 0);
+			continue;
+		} else if (err == 0 || err == UBI_IO_BITFLIPS) {
+			dbg_bld("Found non empty PEB:%i in pool", pnum);
+
+			if (err == UBI_IO_BITFLIPS)
+				scrub = 1;
+
+			found_orphan = 0;
+			list_for_each_entry(tmp_aeb, eba_orphans, u.list) {
+				if (tmp_aeb->pnum == pnum) {
+					found_orphan = 1;
+					break;
+				}
+			}
+			if (found_orphan) {
+				kmem_cache_free(ai->aeb_slab_cache, tmp_aeb);
+				list_del(&tmp_aeb->u.list);
+			}
+
+			new_aeb = kmem_cache_alloc(ai->aeb_slab_cache,
+						   GFP_KERNEL);
+			if (!new_aeb) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			new_aeb->ec = be64_to_cpu(ech->ec);
+			new_aeb->pnum = pnum;
+			new_aeb->lnum = be32_to_cpu(vh->lnum);
+			new_aeb->sqnum = be64_to_cpu(vh->sqnum);
+			new_aeb->copy_flag = vh->copy_flag;
+			new_aeb->scrub = scrub;
+
+			if (*max_sqnum < new_aeb->sqnum)
+				*max_sqnum = new_aeb->sqnum;
+
+			err = process_pool_aeb(ubi, ai, vh, new_aeb);
+			if (err) {
+				ret = err > 0 ? UBI_BAD_FASTMAP : err;
+				goto out;
+			}
+		} else {
+			/* We are paranoid and fall back to scanning mode */
+			ubi_err("fastmap pool PEBs contains damaged PEBs!");
+			ret = err > 0 ? UBI_BAD_FASTMAP : err;
+			goto out;
+		}
+
+	}
+
+out:
+	ubi_free_vid_hdr(ubi, vh);
+	kfree(ech);
+	return ret;
+}
+
+/**
+ * count_fastmap_pebs - Counts the PEBs found by fastmap.
+ * @ai: The UBI attach info object
+ */
+static int count_fastmap_pebs(struct ubi_attach_info *ai)
+{
+	struct ubi_ainf_peb *aeb;
+	struct ubi_ainf_volume *av;
+	struct rb_node *rb1, *rb2;
+	int n = 0;
+
+	list_for_each_entry(aeb, &ai->erase, u.list)
+		n++;
+
+	list_for_each_entry(aeb, &ai->free, u.list)
+		n++;
+
+	 ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
+			n++;
+
+	return n;
+}
+
+/**
+ * ubi_attach_fastmap - creates ubi_attach_info from a fastmap.
+ * @ubi: UBI device object
+ * @ai: UBI attach info object
+ * @fm: the fastmap to be attached
+ *
+ * Returns 0 on success, UBI_BAD_FASTMAP if the found fastmap was unusable.
+ * < 0 indicates an internal error.
+ */
+static int ubi_attach_fastmap(struct ubi_device *ubi,
+			      struct ubi_attach_info *ai,
+			      struct ubi_fastmap_layout *fm)
+{
+	struct list_head used, eba_orphans, free;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb, *tmp_aeb, *_tmp_aeb;
+	struct ubi_ec_hdr *ech;
+	struct ubi_fm_sb *fmsb;
+	struct ubi_fm_hdr *fmhdr;
+	struct ubi_fm_scan_pool *fmpl1, *fmpl2;
+	struct ubi_fm_ec *fmec;
+	struct ubi_fm_volhdr *fmvhdr;
+	struct ubi_fm_eba *fm_eba;
+	int ret, i, j, pool_size, wl_pool_size;
+	size_t fm_pos = 0, fm_size = ubi->fm_size;
+	unsigned long long max_sqnum = 0;
+	void *fm_raw = ubi->fm_buf;
+
+	INIT_LIST_HEAD(&used);
+	INIT_LIST_HEAD(&free);
+	INIT_LIST_HEAD(&eba_orphans);
+	INIT_LIST_HEAD(&ai->corr);
+	INIT_LIST_HEAD(&ai->free);
+	INIT_LIST_HEAD(&ai->erase);
+	INIT_LIST_HEAD(&ai->alien);
+	ai->volumes = RB_ROOT;
+	ai->min_ec = UBI_MAX_ERASECOUNTER;
+
+	ai->aeb_slab_cache = kmem_cache_create("ubi_ainf_peb_slab",
+					       sizeof(struct ubi_ainf_peb),
+					       0, 0, NULL);
+	if (!ai->aeb_slab_cache) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+
+	fmsb = (struct ubi_fm_sb *)(fm_raw);
+	ai->max_sqnum = fmsb->sqnum;
+	fm_pos += sizeof(struct ubi_fm_sb);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+
+	fmhdr = (struct ubi_fm_hdr *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmhdr);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+
+	if (be32_to_cpu(fmhdr->magic) != UBI_FM_HDR_MAGIC) {
+		ubi_err("bad fastmap header magic: 0x%x, expected: 0x%x",
+			be32_to_cpu(fmhdr->magic), UBI_FM_HDR_MAGIC);
+		goto fail_bad;
+	}
+
+	fmpl1 = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl1);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+	if (be32_to_cpu(fmpl1->magic) != UBI_FM_POOL_MAGIC) {
+		ubi_err("bad fastmap pool magic: 0x%x, expected: 0x%x",
+			be32_to_cpu(fmpl1->magic), UBI_FM_POOL_MAGIC);
+		goto fail_bad;
+	}
+
+	fmpl2 = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl2);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+	if (be32_to_cpu(fmpl2->magic) != UBI_FM_POOL_MAGIC) {
+		ubi_err("bad fastmap pool magic: 0x%x, expected: 0x%x",
+			be32_to_cpu(fmpl2->magic), UBI_FM_POOL_MAGIC);
+		goto fail_bad;
+	}
+
+	pool_size = be16_to_cpu(fmpl1->size);
+	wl_pool_size = be16_to_cpu(fmpl2->size);
+	fm->max_pool_size = be16_to_cpu(fmpl1->max_size);
+	fm->max_wl_pool_size = be16_to_cpu(fmpl2->max_size);
+
+	if (pool_size > UBI_FM_MAX_POOL_SIZE || pool_size < 0) {
+		ubi_err("bad pool size: %i", pool_size);
+		goto fail_bad;
+	}
+
+	if (wl_pool_size > UBI_FM_MAX_POOL_SIZE || wl_pool_size < 0) {
+		ubi_err("bad WL pool size: %i", wl_pool_size);
+		goto fail_bad;
+	}
+
+
+	if (fm->max_pool_size > UBI_FM_MAX_POOL_SIZE ||
+	    fm->max_pool_size < 0) {
+		ubi_err("bad maximal pool size: %i", fm->max_pool_size);
+		goto fail_bad;
+	}
+
+	if (fm->max_wl_pool_size > UBI_FM_MAX_POOL_SIZE ||
+	    fm->max_wl_pool_size < 0) {
+		ubi_err("bad maximal WL pool size: %i", fm->max_wl_pool_size);
+		goto fail_bad;
+	}
+
+	/* read EC values from free list */
+	for (i = 0; i < be32_to_cpu(fmhdr->free_peb_count); i++) {
+		fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmec);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		add_aeb(ai, &ai->free, be32_to_cpu(fmec->pnum),
+			be32_to_cpu(fmec->ec), 0);
+	}
+
+	/* read EC values from used list */
+	for (i = 0; i < be32_to_cpu(fmhdr->used_peb_count); i++) {
+		fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmec);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
+			be32_to_cpu(fmec->ec), 0);
+	}
+
+	/* read EC values from scrub list */
+	for (i = 0; i < be32_to_cpu(fmhdr->scrub_peb_count); i++) {
+		fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmec);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
+			be32_to_cpu(fmec->ec), 1);
+	}
+
+	/* read EC values from erase list */
+	for (i = 0; i < be32_to_cpu(fmhdr->erase_peb_count); i++) {
+		fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmec);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		add_aeb(ai, &ai->erase, be32_to_cpu(fmec->pnum),
+			be32_to_cpu(fmec->ec), 1);
+	}
+
+	ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
+	ai->bad_peb_count = be32_to_cpu(fmhdr->bad_peb_count);
+
+	/* Iterate over all volumes and read their EBA table */
+	for (i = 0; i < be32_to_cpu(fmhdr->vol_count); i++) {
+		fmvhdr = (struct ubi_fm_volhdr *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmvhdr);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		if (be32_to_cpu(fmvhdr->magic) != UBI_FM_VHDR_MAGIC) {
+			ubi_err("bad fastmap vol header magic: 0x%x, " \
+				"expected: 0x%x",
+				be32_to_cpu(fmvhdr->magic), UBI_FM_VHDR_MAGIC);
+			goto fail_bad;
+		}
+
+		av = add_vol(ai, be32_to_cpu(fmvhdr->vol_id),
+			     be32_to_cpu(fmvhdr->used_ebs),
+			     be32_to_cpu(fmvhdr->data_pad),
+			     fmvhdr->vol_type,
+			     be32_to_cpu(fmvhdr->last_eb_bytes));
+
+		if (!av)
+			goto fail_bad;
+
+		ai->vols_found++;
+		if (ai->highest_vol_id < be32_to_cpu(fmvhdr->vol_id))
+			ai->highest_vol_id = be32_to_cpu(fmvhdr->vol_id);
+
+		fm_eba = (struct ubi_fm_eba *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fm_eba);
+		fm_pos += (sizeof(__be32) * be32_to_cpu(fm_eba->reserved_pebs));
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		if (be32_to_cpu(fm_eba->magic) != UBI_FM_EBA_MAGIC) {
+			ubi_err("bad fastmap EBA header magic: 0x%x, " \
+				"expected: 0x%x",
+				be32_to_cpu(fm_eba->magic), UBI_FM_EBA_MAGIC);
+			goto fail_bad;
+		}
+
+		for (j = 0; j < be32_to_cpu(fm_eba->reserved_pebs); j++) {
+			int pnum = be32_to_cpu(fm_eba->pnum[j]);
+
+			if ((int)be32_to_cpu(fm_eba->pnum[j]) < 0)
+				continue;
+
+			aeb = NULL;
+			list_for_each_entry(tmp_aeb, &used, u.list) {
+				if (tmp_aeb->pnum == pnum)
+					aeb = tmp_aeb;
+			}
+
+			/* This can happen if a PEB is already in an EBA known
+			 * by this fastmap but the PEB itself is not in the used
+			 * list.
+			 * In this case the PEB can be within the fastmap pool
+			 * or while writing the fastmap it was in the protection
+			 * queue.
+			 */
+			if (!aeb) {
+				aeb = kmem_cache_alloc(ai->aeb_slab_cache,
+						       GFP_KERNEL);
+				if (!aeb) {
+					ret = -ENOMEM;
+
+					goto fail;
+				}
+
+				aeb->lnum = j;
+				aeb->pnum = be32_to_cpu(fm_eba->pnum[j]);
+				aeb->ec = -1;
+				aeb->scrub = aeb->copy_flag = aeb->sqnum = 0;
+				list_add_tail(&aeb->u.list, &eba_orphans);
+				continue;
+			}
+
+			aeb->lnum = j;
+
+			if (av->highest_lnum <= aeb->lnum)
+				av->highest_lnum = aeb->lnum;
+
+			assign_aeb_to_av(ai, aeb, av);
+
+			dbg_bld("inserting PEB:%i (LEB %i) to vol %i",
+				aeb->pnum, aeb->lnum, av->vol_id);
+		}
+
+		ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+		if (!ech) {
+			ret = -ENOMEM;
+			goto fail;
+		}
+
+		list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &eba_orphans,
+					 u.list) {
+			int err;
+
+			if (ubi_io_is_bad(ubi, tmp_aeb->pnum)) {
+				ubi_err("bad PEB in fastmap EBA orphan list");
+				ret = UBI_BAD_FASTMAP;
+				kfree(ech);
+				goto fail;
+			}
+
+			err = ubi_io_read_ec_hdr(ubi, tmp_aeb->pnum, ech, 0);
+			if (err && err != UBI_IO_BITFLIPS) {
+				ubi_err("unable to read EC header! PEB:%i " \
+					"err:%i", tmp_aeb->pnum, err);
+				ret = err > 0 ? UBI_BAD_FASTMAP : err;
+				kfree(ech);
+
+				goto fail;
+			} else if (err == UBI_IO_BITFLIPS)
+				tmp_aeb->scrub = 1;
+
+			tmp_aeb->ec = be64_to_cpu(ech->ec);
+			assign_aeb_to_av(ai, tmp_aeb, av);
+		}
+
+		kfree(ech);
+	}
+
+	ret = scan_pool(ubi, ai, fmpl1->pebs, pool_size, &max_sqnum,
+			&eba_orphans, &free);
+	if (ret)
+		goto fail;
+
+	ret = scan_pool(ubi, ai, fmpl2->pebs, wl_pool_size, &max_sqnum,
+			&eba_orphans, &free);
+	if (ret)
+		goto fail;
+
+	if (max_sqnum > ai->max_sqnum)
+		ai->max_sqnum = max_sqnum;
+
+	list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &free, u.list) {
+		list_del(&tmp_aeb->u.list);
+		list_add_tail(&tmp_aeb->u.list, &ai->free);
+	}
+
+	/*
+	 * If fastmap is leaking PEBs (must not happen), raise a
+	 * fat warning and fall back to scanning mode.
+	 * We do this here because in ubi_wl_init() it's too late
+	 * and we cannot fall back to scanning.
+	 */
+	if (WARN_ON(count_fastmap_pebs(ai) != ubi->peb_count -
+		    ai->bad_peb_count - fm->used_blocks))
+		goto fail_bad;
+
+	return 0;
+
+fail_bad:
+	ret = UBI_BAD_FASTMAP;
+fail:
+	return ret;
+}
+
+/**
+ * ubi_scan_fastmap - scan the fastmap.
+ * @ubi: UBI device object
+ * @ai: UBI attach info to be filled
+ * @fm_anchor: The fastmap starts at this PEB
+ *
+ * Returns 0 on success, UBI_NO_FASTMAP if no fastmap was found,
+ * UBI_BAD_FASTMAP if one was found but is not usable.
+ * < 0 indicates an internal error.
+ */
+int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		     int fm_anchor)
+{
+	struct ubi_fm_sb *fmsb;
+	struct ubi_vid_hdr *vh;
+	struct ubi_ec_hdr *ech;
+	struct ubi_fastmap_layout *fm;
+	int i, used_blocks, pnum, ret = 0;
+	size_t fm_size;
+	__be32 crc, tmp_crc;
+	unsigned long long sqnum = 0;
+
+	mutex_lock(&ubi->fm_mutex);
+	memset(ubi->fm_buf, 0, ubi->fm_size);
+
+	fmsb = kmalloc(sizeof(*fmsb), GFP_KERNEL);
+	if (!fmsb) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	fm = kzalloc(sizeof(*fm), GFP_KERNEL);
+	if (!fm) {
+		ret = -ENOMEM;
+		kfree(fmsb);
+		goto out;
+	}
+
+	ret = ubi_io_read(ubi, fmsb, fm_anchor, ubi->leb_start, sizeof(*fmsb));
+	if (ret && ret != UBI_IO_BITFLIPS) {
+		kfree(fmsb);
+		kfree(fm);
+		goto out;
+	} else if (ret == UBI_IO_BITFLIPS)
+		fm->to_be_tortured[0] = 1;
+
+	if (be32_to_cpu(fmsb->magic) != UBI_FM_SB_MAGIC) {
+		ubi_err("bad super block magic: 0x%x, expected: 0x%x",
+			be32_to_cpu(fmsb->magic), UBI_FM_SB_MAGIC);
+		ret = UBI_BAD_FASTMAP;
+		kfree(fmsb);
+		kfree(fm);
+		goto out;
+	}
+
+	if (fmsb->version != UBI_FM_FMT_VERSION) {
+		ubi_err("bad fastmap version: %i, expected: %i",
+			fmsb->version, UBI_FM_FMT_VERSION);
+		ret = UBI_BAD_FASTMAP;
+		kfree(fmsb);
+		kfree(fm);
+		goto out;
+	}
+
+	used_blocks = be32_to_cpu(fmsb->used_blocks);
+	if (used_blocks > UBI_FM_MAX_BLOCKS || used_blocks < 1) {
+		ubi_err("number of fastmap blocks is invalid: %i", used_blocks);
+		ret = UBI_BAD_FASTMAP;
+		kfree(fmsb);
+		kfree(fm);
+		goto out;
+	}
+
+	fm_size = ubi->leb_size * used_blocks;
+	if (fm_size != ubi->fm_size) {
+		ubi_err("bad fastmap size: %zi, expected: %zi", fm_size,
+			ubi->fm_size);
+		ret = UBI_BAD_FASTMAP;
+		kfree(fmsb);
+		kfree(fm);
+	}
+
+	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ech) {
+		ret = -ENOMEM;
+		kfree(fmsb);
+		kfree(fm);
+		goto out;
+	}
+
+	vh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+	if (!vh) {
+		ret = -ENOMEM;
+		kfree(fmsb);
+		kfree(fm);
+		kfree(ech);
+		goto out;
+	}
+
+	for (i = 0; i < used_blocks; i++) {
+		pnum = be32_to_cpu(fmsb->block_loc[i]);
+
+		if (ubi_io_is_bad(ubi, pnum)) {
+			ret = UBI_BAD_FASTMAP;
+			kfree(fm);
+			kfree(fmsb);
+			goto free_hdr;
+		}
+
+		ret = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+		if (ret && ret != UBI_IO_BITFLIPS) {
+			ubi_err("unable to read fastmap block# %i EC (PEB: %i)",
+				i, pnum);
+			if (ret > 0)
+				ret = UBI_BAD_FASTMAP;
+			kfree(fmsb);
+			kfree(fm);
+			goto free_hdr;
+		} else if (ret == UBI_IO_BITFLIPS)
+			fm->to_be_tortured[i] = 1;
+
+		if (!ubi->image_seq)
+			ubi->image_seq = be32_to_cpu(ech->image_seq);
+
+		if (be32_to_cpu(ech->image_seq) != ubi->image_seq) {
+			ret = UBI_BAD_FASTMAP;
+			kfree(fmsb);
+			kfree(fm);
+			goto free_hdr;
+		}
+
+		ret = ubi_io_read_vid_hdr(ubi, pnum, vh, 0);
+		if (ret && ret != UBI_IO_BITFLIPS) {
+			ubi_err("unable to read fastmap block# %i (PEB: %i)",
+				i, pnum);
+			kfree(fmsb);
+			kfree(fm);
+			goto free_hdr;
+		}
+
+		if (i == 0) {
+			if (be32_to_cpu(vh->vol_id) != UBI_FM_SB_VOLUME_ID) {
+				ubi_err("bad fastmap anchor vol_id: 0x%x," \
+					" expected: 0x%x",
+					be32_to_cpu(vh->vol_id),
+					UBI_FM_SB_VOLUME_ID);
+				ret = UBI_BAD_FASTMAP;
+				kfree(fmsb);
+				kfree(fm);
+				goto free_hdr;
+			}
+		} else {
+			if (be32_to_cpu(vh->vol_id) != UBI_FM_DATA_VOLUME_ID) {
+				ubi_err("bad fastmap data vol_id: 0x%x," \
+					" expected: 0x%x",
+					be32_to_cpu(vh->vol_id),
+					UBI_FM_DATA_VOLUME_ID);
+				ret = UBI_BAD_FASTMAP;
+				kfree(fmsb);
+				goto free_hdr;
+			}
+		}
+
+		if (sqnum < be64_to_cpu(vh->sqnum))
+			sqnum = be64_to_cpu(vh->sqnum);
+
+		ret = ubi_io_read(ubi, ubi->fm_buf + (ubi->leb_size * i), pnum,
+				  ubi->leb_start, ubi->leb_size);
+		if (ret && ret != UBI_IO_BITFLIPS) {
+			ubi_err("unable to read fastmap block# %i (PEB: %i, " \
+				"err: %i)", i, pnum, ret);
+			kfree(fmsb);
+			kfree(fm);
+			goto free_hdr;
+		}
+	}
+
+	kfree(fmsb);
+
+	fmsb = (struct ubi_fm_sb *)(ubi->fm_buf);
+	tmp_crc = be32_to_cpu(fmsb->data_crc);
+	fmsb->data_crc = 0;
+	crc = crc32(UBI_CRC32_INIT, ubi->fm_buf, fm_size);
+	if (crc != tmp_crc) {
+		ubi_err("fastmap data CRC is invalid");
+		ubi_err("CRC should be: 0x%x, calc: 0x%x", tmp_crc, crc);
+		ret = UBI_BAD_FASTMAP;
+		kfree(fm);
+		goto free_hdr;
+	}
+
+	fmsb->sqnum = sqnum;
+
+	fm->used_blocks = used_blocks;
+
+	ret = ubi_attach_fastmap(ubi, ai, fm);
+	if (ret) {
+		if (ret > 0)
+			ret = UBI_BAD_FASTMAP;
+		kfree(fm);
+		goto free_hdr;
+	}
+
+	for (i = 0; i < used_blocks; i++) {
+		struct ubi_wl_entry *e;
+
+		e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+		if (!e) {
+			while (i--)
+				kfree(fm->e[i]);
+
+			kfree(fm);
+			fm = NULL;
+			ret = -ENOMEM;
+			goto free_hdr;
+		}
+
+		e->pnum = be32_to_cpu(fmsb->block_loc[i]);
+		e->ec = be32_to_cpu(fmsb->block_ec[i]);
+		fm->e[i] = e;
+	}
+
+	ubi->fm = fm;
+	ubi->fm_pool.max_size = ubi->fm->max_pool_size;
+	ubi->fm_wl_pool.max_size = ubi->fm->max_wl_pool_size;
+	ubi_msg("attached by fastmap");
+	ubi_msg("fastmap pool size: %d", ubi->fm_pool.max_size);
+	ubi_msg("fastmap WL pool size: %d", ubi->fm_wl_pool.max_size);
+	ubi->fm_disabled = 0;
+
+free_hdr:
+	ubi_free_vid_hdr(ubi, vh);
+	kfree(ech);
+out:
+	mutex_unlock(&ubi->fm_mutex);
+	if (ret == UBI_BAD_FASTMAP)
+		ubi_err("Attach by fastmap failed, doing a full scan!");
+	return ret;
+}
+
+/**
+ * ubi_write_fastmap - writes a fastmap.
+ * @ubi: UBI device object
+ * @new_fm: the to be written fastmap
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int ubi_write_fastmap(struct ubi_device *ubi,
+			     struct ubi_fastmap_layout *new_fm)
+{
+	size_t fm_pos = 0;
+	void *fm_raw;
+	struct ubi_fm_sb *fmsb;
+	struct ubi_fm_hdr *fmh;
+	struct ubi_fm_scan_pool *fmpl1, *fmpl2;
+	struct ubi_fm_ec *fec;
+	struct ubi_fm_volhdr *fvh;
+	struct ubi_fm_eba *feba;
+	struct rb_node *node;
+	struct ubi_wl_entry *wl_e;
+	struct ubi_volume *vol;
+	struct ubi_vid_hdr *avhdr, *dvhdr;
+	struct ubi_work *ubi_wrk;
+	int ret, i, j, free_peb_count, used_peb_count, vol_count;
+	int scrub_peb_count, erase_peb_count;
+
+	fm_raw = ubi->fm_buf;
+	memset(ubi->fm_buf, 0, ubi->fm_size);
+
+	avhdr = new_fm_vhdr(ubi, UBI_FM_SB_VOLUME_ID);
+	if (!avhdr) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	dvhdr = new_fm_vhdr(ubi, UBI_FM_DATA_VOLUME_ID);
+	if (!dvhdr) {
+		ret = -ENOMEM;
+		goto out_kfree;
+	}
+
+	spin_lock(&ubi->volumes_lock);
+	spin_lock(&ubi->wl_lock);
+
+	fmsb = (struct ubi_fm_sb *)fm_raw;
+	fm_pos += sizeof(*fmsb);
+	ubi_assert(fm_pos <= ubi->fm_size);
+
+	fmh = (struct ubi_fm_hdr *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmh);
+	ubi_assert(fm_pos <= ubi->fm_size);
+
+	fmsb->magic = cpu_to_be32(UBI_FM_SB_MAGIC);
+	fmsb->version = UBI_FM_FMT_VERSION;
+	fmsb->used_blocks = cpu_to_be32(new_fm->used_blocks);
+	/* the max sqnum will be filled in while *reading* the fastmap */
+	fmsb->sqnum = 0;
+
+	fmh->magic = cpu_to_be32(UBI_FM_HDR_MAGIC);
+	free_peb_count = 0;
+	used_peb_count = 0;
+	scrub_peb_count = 0;
+	erase_peb_count = 0;
+	vol_count = 0;
+
+	fmpl1 = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl1);
+	fmpl1->magic = cpu_to_be32(UBI_FM_POOL_MAGIC);
+	fmpl1->size = cpu_to_be16(ubi->fm_pool.size);
+	fmpl1->max_size = cpu_to_be16(ubi->fm_pool.max_size);
+
+	for (i = 0; i < ubi->fm_pool.size; i++)
+		fmpl1->pebs[i] = cpu_to_be32(ubi->fm_pool.pebs[i]);
+
+	fmpl2 = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl2);
+	fmpl2->magic = cpu_to_be32(UBI_FM_POOL_MAGIC);
+	fmpl2->size = cpu_to_be16(ubi->fm_wl_pool.size);
+	fmpl2->max_size = cpu_to_be16(ubi->fm_wl_pool.max_size);
+
+	for (i = 0; i < ubi->fm_wl_pool.size; i++)
+		fmpl2->pebs[i] = cpu_to_be32(ubi->fm_wl_pool.pebs[i]);
+
+	for (node = rb_first(&ubi->free); node; node = rb_next(node)) {
+		wl_e = rb_entry(node, struct ubi_wl_entry, u.rb);
+		fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+		fec->pnum = cpu_to_be32(wl_e->pnum);
+		fec->ec = cpu_to_be32(wl_e->ec);
+
+		free_peb_count++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= ubi->fm_size);
+	}
+	fmh->free_peb_count = cpu_to_be32(free_peb_count);
+
+	for (node = rb_first(&ubi->used); node; node = rb_next(node)) {
+		wl_e = rb_entry(node, struct ubi_wl_entry, u.rb);
+		fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+		fec->pnum = cpu_to_be32(wl_e->pnum);
+		fec->ec = cpu_to_be32(wl_e->ec);
+
+		used_peb_count++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= ubi->fm_size);
+	}
+	fmh->used_peb_count = cpu_to_be32(used_peb_count);
+
+	for (node = rb_first(&ubi->scrub); node; node = rb_next(node)) {
+		wl_e = rb_entry(node, struct ubi_wl_entry, u.rb);
+		fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+		fec->pnum = cpu_to_be32(wl_e->pnum);
+		fec->ec = cpu_to_be32(wl_e->ec);
+
+		scrub_peb_count++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= ubi->fm_size);
+	}
+	fmh->scrub_peb_count = cpu_to_be32(scrub_peb_count);
+
+
+	list_for_each_entry(ubi_wrk, &ubi->works, list) {
+		if (ubi_is_erase_work(ubi_wrk)) {
+			wl_e = ubi_wrk->e;
+			ubi_assert(wl_e);
+
+			fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+			fec->pnum = cpu_to_be32(wl_e->pnum);
+			fec->ec = cpu_to_be32(wl_e->ec);
+
+			erase_peb_count++;
+			fm_pos += sizeof(*fec);
+			ubi_assert(fm_pos <= ubi->fm_size);
+		}
+	}
+	fmh->erase_peb_count = cpu_to_be32(erase_peb_count);
+
+	for (i = 0; i < UBI_MAX_VOLUMES + UBI_INT_VOL_COUNT; i++) {
+		vol = ubi->volumes[i];
+
+		if (!vol)
+			continue;
+
+		vol_count++;
+
+		fvh = (struct ubi_fm_volhdr *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fvh);
+		ubi_assert(fm_pos <= ubi->fm_size);
+
+		fvh->magic = cpu_to_be32(UBI_FM_VHDR_MAGIC);
+		fvh->vol_id = cpu_to_be32(vol->vol_id);
+		fvh->vol_type = vol->vol_type;
+		fvh->used_ebs = cpu_to_be32(vol->used_ebs);
+		fvh->data_pad = cpu_to_be32(vol->data_pad);
+		fvh->last_eb_bytes = cpu_to_be32(vol->last_eb_bytes);
+
+		ubi_assert(vol->vol_type == UBI_DYNAMIC_VOLUME ||
+			vol->vol_type == UBI_STATIC_VOLUME);
+
+		feba = (struct ubi_fm_eba *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*feba) + (sizeof(__be32) * vol->reserved_pebs);
+		ubi_assert(fm_pos <= ubi->fm_size);
+
+		for (j = 0; j < vol->reserved_pebs; j++)
+			feba->pnum[j] = cpu_to_be32(vol->eba_tbl[j]);
+
+		feba->reserved_pebs = cpu_to_be32(j);
+		feba->magic = cpu_to_be32(UBI_FM_EBA_MAGIC);
+	}
+	fmh->vol_count = cpu_to_be32(vol_count);
+	fmh->bad_peb_count = cpu_to_be32(ubi->bad_peb_count);
+
+	avhdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	avhdr->lnum = 0;
+
+	spin_unlock(&ubi->wl_lock);
+	spin_unlock(&ubi->volumes_lock);
+
+	dbg_bld("writing fastmap SB to PEB %i", new_fm->e[0]->pnum);
+	ret = ubi_io_write_vid_hdr(ubi, new_fm->e[0]->pnum, avhdr);
+	if (ret) {
+		ubi_err("unable to write vid_hdr to fastmap SB!");
+		goto out_kfree;
+	}
+
+	for (i = 0; i < new_fm->used_blocks; i++) {
+		fmsb->block_loc[i] = cpu_to_be32(new_fm->e[i]->pnum);
+		fmsb->block_ec[i] = cpu_to_be32(new_fm->e[i]->ec);
+	}
+
+	fmsb->data_crc = 0;
+	fmsb->data_crc = cpu_to_be32(crc32(UBI_CRC32_INIT, fm_raw,
+					   ubi->fm_size));
+
+	for (i = 1; i < new_fm->used_blocks; i++) {
+		dvhdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+		dvhdr->lnum = cpu_to_be32(i);
+		dbg_bld("writing fastmap data to PEB %i sqnum %llu",
+			new_fm->e[i]->pnum, be64_to_cpu(dvhdr->sqnum));
+		ret = ubi_io_write_vid_hdr(ubi, new_fm->e[i]->pnum, dvhdr);
+		if (ret) {
+			ubi_err("unable to write vid_hdr to PEB %i!",
+				new_fm->e[i]->pnum);
+			goto out_kfree;
+		}
+	}
+
+	for (i = 0; i < new_fm->used_blocks; i++) {
+		ret = ubi_io_write(ubi, fm_raw + (i * ubi->leb_size),
+			new_fm->e[i]->pnum, ubi->leb_start, ubi->leb_size);
+		if (ret) {
+			ubi_err("unable to write fastmap to PEB %i!",
+				new_fm->e[i]->pnum);
+			goto out_kfree;
+		}
+	}
+
+	ubi_assert(new_fm);
+	ubi->fm = new_fm;
+
+	dbg_bld("fastmap written!");
+
+out_kfree:
+	ubi_free_vid_hdr(ubi, avhdr);
+	ubi_free_vid_hdr(ubi, dvhdr);
+out:
+	return ret;
+}
+
+/**
+ * erase_block - Manually erase a PEB.
+ * @ubi: UBI device object
+ * @pnum: PEB to be erased
+ *
+ * Returns the new EC value on success, < 0 indicates an internal error.
+ */
+static int erase_block(struct ubi_device *ubi, int pnum)
+{
+	int ret;
+	struct ubi_ec_hdr *ec_hdr;
+	long long ec;
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ec_hdr)
+		return -ENOMEM;
+
+	ret = ubi_io_read_ec_hdr(ubi, pnum, ec_hdr, 0);
+	if (ret < 0)
+		goto out;
+	else if (ret && ret != UBI_IO_BITFLIPS) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = ubi_io_sync_erase(ubi, pnum, 0);
+	if (ret < 0)
+		goto out;
+
+	ec = be64_to_cpu(ec_hdr->ec);
+	ec += ret;
+	if (ec > UBI_MAX_ERASECOUNTER) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ec_hdr->ec = cpu_to_be64(ec);
+	ret = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
+	if (ret < 0)
+		goto out;
+
+	ret = ec;
+out:
+	kfree(ec_hdr);
+	return ret;
+}
+
+/**
+ * invalidate_fastmap - destroys a fastmap.
+ * @ubi: UBI device object
+ * @fm: the fastmap to be destroyed
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int invalidate_fastmap(struct ubi_device *ubi,
+			      struct ubi_fastmap_layout *fm)
+{
+	int ret, i;
+	struct ubi_vid_hdr *vh;
+
+	ret = erase_block(ubi, fm->e[0]->pnum);
+	if (ret < 0)
+		return ret;
+
+	vh = new_fm_vhdr(ubi, UBI_FM_SB_VOLUME_ID);
+	if (!vh)
+		return -ENOMEM;
+
+	/* deleting the current fastmap SB is not enough, an old SB may exist,
+	 * so create a (corrupted) SB such that fastmap will find it and fall
+	 * back to scanning mode in any case */
+	vh->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	ret = ubi_io_write_vid_hdr(ubi, fm->e[0]->pnum, vh);
+
+	for (i = 0; i < fm->used_blocks; i++)
+		ubi_wl_put_fm_peb(ubi, fm->e[i], i, fm->to_be_tortured[i]);
+
+	return ret;
+}
+
+/**
+ * ubi_update_fastmap - will be called by UBI if a volume changes or
+ * a fastmap pool becomes full.
+ * @ubi: UBI device object
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+int ubi_update_fastmap(struct ubi_device *ubi)
+{
+	int ret, i;
+	struct ubi_fastmap_layout *new_fm, *old_fm;
+	struct ubi_wl_entry *tmp_e;
+
+	mutex_lock(&ubi->fm_mutex);
+
+	ubi_refill_pools(ubi);
+
+	if (ubi->ro_mode || ubi->fm_disabled) {
+		mutex_unlock(&ubi->fm_mutex);
+		return 0;
+	}
+
+	ret = ubi_ensure_anchor_pebs(ubi);
+	if (ret) {
+		mutex_unlock(&ubi->fm_mutex);
+		return ret;
+	}
+
+	new_fm = kzalloc(sizeof(*new_fm), GFP_KERNEL);
+	if (!new_fm) {
+		mutex_unlock(&ubi->fm_mutex);
+		return -ENOMEM;
+	}
+
+	new_fm->used_blocks = ubi->fm_size / ubi->leb_size;
+
+	for (i = 0; i < new_fm->used_blocks; i++) {
+		new_fm->e[i] = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+		if (!new_fm->e[i]) {
+			while (i--)
+				kfree(new_fm->e[i]);
+
+			kfree(new_fm);
+			mutex_unlock(&ubi->fm_mutex);
+			return -ENOMEM;
+		}
+	}
+
+	old_fm = ubi->fm;
+	ubi->fm = NULL;
+
+	if (new_fm->used_blocks > UBI_FM_MAX_BLOCKS) {
+		ubi_err("fastmap too large");
+		ret = -ENOSPC;
+		goto err;
+	}
+
+	for (i = 1; i < new_fm->used_blocks; i++) {
+		spin_lock(&ubi->wl_lock);
+		tmp_e = ubi_wl_get_fm_peb(ubi, 0);
+		spin_unlock(&ubi->wl_lock);
+
+		if (!tmp_e && !old_fm) {
+			int j;
+			ubi_err("could not get any free erase block");
+
+			for (j = 1; j < i; j++)
+				ubi_wl_put_fm_peb(ubi, new_fm->e[j], j, 0);
+
+			ret = -ENOSPC;
+			goto err;
+		} else if (!tmp_e && old_fm) {
+			ret = erase_block(ubi, old_fm->e[i]->pnum);
+			if (ret < 0) {
+				int j;
+
+				for (j = 1; j < i; j++)
+					ubi_wl_put_fm_peb(ubi, new_fm->e[j],
+							  j, 0);
+
+				ubi_err("could not erase old fastmap PEB");
+				goto err;
+			}
+
+			new_fm->e[i]->pnum = old_fm->e[i]->pnum;
+			new_fm->e[i]->ec = old_fm->e[i]->ec;
+		} else {
+			new_fm->e[i]->pnum = tmp_e->pnum;
+			new_fm->e[i]->ec = tmp_e->ec;
+
+			if (old_fm)
+				ubi_wl_put_fm_peb(ubi, old_fm->e[i], i,
+						  old_fm->to_be_tortured[i]);
+		}
+	}
+
+	spin_lock(&ubi->wl_lock);
+	tmp_e = ubi_wl_get_fm_peb(ubi, 1);
+	spin_unlock(&ubi->wl_lock);
+
+	if (old_fm) {
+		/* no fresh anchor PEB was found, reuse the old one */
+		if (!tmp_e) {
+			ret = erase_block(ubi, old_fm->e[0]->pnum);
+			if (ret < 0) {
+				int i;
+				ubi_err("could not erase old anchor PEB");
+
+				for (i = 1; i < new_fm->used_blocks; i++)
+					ubi_wl_put_fm_peb(ubi, new_fm->e[i],
+							  i, 0);
+				goto err;
+			}
+
+			new_fm->e[0]->pnum = old_fm->e[0]->pnum;
+			new_fm->e[0]->ec = ret;
+		} else {
+			/* we've got a new anchor PEB, return the old one */
+			ubi_wl_put_fm_peb(ubi, old_fm->e[0], 0,
+					  old_fm->to_be_tortured[0]);
+
+			new_fm->e[0]->pnum = tmp_e->pnum;
+			new_fm->e[0]->ec = tmp_e->ec;
+		}
+	} else {
+		if (!tmp_e) {
+			int i;
+			ubi_err("could not find any anchor PEB");
+
+			for (i = 1; i < new_fm->used_blocks; i++)
+				ubi_wl_put_fm_peb(ubi, new_fm->e[i], i, 0);
+
+			ret = -ENOSPC;
+			goto err;
+		}
+
+		new_fm->e[0]->pnum = tmp_e->pnum;
+		new_fm->e[0]->ec = tmp_e->ec;
+	}
+
+	down_write(&ubi->work_sem);
+	down_write(&ubi->fm_sem);
+	ret = ubi_write_fastmap(ubi, new_fm);
+	up_write(&ubi->fm_sem);
+	up_write(&ubi->work_sem);
+
+	if (ret)
+		goto err;
+
+out_unlock:
+	mutex_unlock(&ubi->fm_mutex);
+	kfree(old_fm);
+	return ret;
+
+err:
+	kfree(new_fm);
+
+	ubi_warn("Unable to write new fastmap, err=%i", ret);
+
+	ret = 0;
+	if (old_fm) {
+		ret = invalidate_fastmap(ubi, old_fm);
+		if (ret < 0)
+			ubi_err("Unable to invalidiate current fastmap!");
+		else if (ret)
+			ret = 0;
+	}
+	goto out_unlock;
+}