Patchwork [RFC] UBI: Implement Fastmap support

login
register
mail settings
Submitter Richard Weinberger
Date May 23, 2012, 11:06 a.m.
Message ID <1337771191-95358-2-git-send-email-richard@nod.at>
Download mbox | patch
Permalink /patch/160909/
State New
Headers show

Comments

Richard Weinberger - May 23, 2012, 11:06 a.m.
Fastmap (aka checkpointing) allows attaching of an UBI volume in nearly
constant time. Only a fixed number of PEBs has to be scanned.

Signed-off-by: Richard Weinberger <richard@nod.at>
---
 drivers/mtd/ubi/Makefile    |    2 +-
 drivers/mtd/ubi/attach.c    |   34 +-
 drivers/mtd/ubi/build.c     |   25 +
 drivers/mtd/ubi/eba.c       |   18 +-
 drivers/mtd/ubi/fastmap.c   | 1240 +++++++++++++++++++++++++++++++++++++++++++
 drivers/mtd/ubi/ubi-media.h |  119 +++++
 drivers/mtd/ubi/ubi.h       |   68 +++-
 drivers/mtd/ubi/wl.c        |  184 +++++++-
 8 files changed, 1667 insertions(+), 23 deletions(-)
 create mode 100644 drivers/mtd/ubi/fastmap.c
Adrian Hunter - May 31, 2012, 10:37 a.m.
On 23/05/12 14:06, Richard Weinberger wrote:
> Fastmap (aka checkpointing) allows attaching of an UBI volume in nearly
> constant time. Only a fixed number of PEBs has to be scanned.
> 
> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
>  drivers/mtd/ubi/Makefile    |    2 +-
>  drivers/mtd/ubi/attach.c    |   34 +-
>  drivers/mtd/ubi/build.c     |   25 +
>  drivers/mtd/ubi/eba.c       |   18 +-
>  drivers/mtd/ubi/fastmap.c   | 1240 +++++++++++++++++++++++++++++++++++++++++++
>  drivers/mtd/ubi/ubi-media.h |  119 +++++
>  drivers/mtd/ubi/ubi.h       |   68 +++-
>  drivers/mtd/ubi/wl.c        |  184 +++++++-
>  8 files changed, 1667 insertions(+), 23 deletions(-)
>  create mode 100644 drivers/mtd/ubi/fastmap.c
> 

...

> diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
> new file mode 100644
> index 0000000..7757e5a

...

> +/**
> + * ubi_find_fastmap - searches the first UBI_FM_MAX_START PEBs for the
> + * fastmap super block.
> + * @ubi: UBI device object
> + */
> +static int ubi_find_fastmap(struct ubi_device *ubi, int *fm_start)
> +{
> +	int i, ret;
> +	struct ubi_vid_hdr *vhdr;
> +
> +	vhdr = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
> +	if (!vhdr)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < UBI_FM_MAX_START; i++) {
> +		ret = ubi_io_read_vid_hdr(ubi, i, vhdr, 0);
> +		if (ret < 0)
> +			break;
> +		else if (ret > 0)
> +			continue;
> +
> +		if (be32_to_cpu(vhdr->vol_id) == UBI_FM_SB_VOLUME_ID) {
> +			*fm_start = i;
> +			dbg_bld("Found fastmap super block at PEB %i\n", i);
> +			ret = 0;
> +
> +			break;

How do you know that this is the current fastmap and not a remnant of an old
fastmap?

> +		}
> +	}
> +
> +	ubi_free_vid_hdr(ubi, vhdr);
> +
> +	return ret;
> +}
Richard Weinberger - May 31, 2012, 1:31 p.m.
Am 31.05.2012 12:37, schrieb Adrian Hunter:
> How do you know that this is the current fastmap and not a remnant of an old
> fastmap?

In the current fastmap we delete always the old one upon attaching.
But I think it would to better to scan all UBI_FM_MAX_START PEBs
and pick the super block with the highest sequence number.

Thanks,
//richard
Adrian Hunter - June 1, 2012, 5:47 a.m.
On 23/05/12 14:06, Richard Weinberger wrote:
> Fastmap (aka checkpointing) allows attaching of an UBI volume in nearly
> constant time. Only a fixed number of PEBs has to be scanned.
> 
> Signed-off-by: Richard Weinberger <richard@nod.at>
> ---
>  drivers/mtd/ubi/Makefile    |    2 +-
>  drivers/mtd/ubi/attach.c    |   34 +-
>  drivers/mtd/ubi/build.c     |   25 +
>  drivers/mtd/ubi/eba.c       |   18 +-
>  drivers/mtd/ubi/fastmap.c   | 1240 +++++++++++++++++++++++++++++++++++++++++++
>  drivers/mtd/ubi/ubi-media.h |  119 +++++
>  drivers/mtd/ubi/ubi.h       |   68 +++-
>  drivers/mtd/ubi/wl.c        |  184 +++++++-
>  8 files changed, 1667 insertions(+), 23 deletions(-)
>  create mode 100644 drivers/mtd/ubi/fastmap.c
> 

...

> diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
> new file mode 100644
> index 0000000..7757e5a
> --- /dev/null
> +++ b/drivers/mtd/ubi/fastmap.c

...

> +/**
> + * ubi_update_fastmap - will be called by UBI if a volume changes or
> + * a fastmap pool becomes full.
> + * @ubi: UBI device object
> + */
> +int ubi_update_fastmap(struct ubi_device *ubi)
> +{
> +	int ret, i;
> +	struct ubi_fastmap_layout *new_fm;
> +
> +	if (ubi->ro_mode)
> +		return 0;
> +
> +	new_fm = kzalloc(sizeof(*new_fm), GFP_KERNEL);
> +	if (!new_fm)
> +		return -ENOMEM;
> +
> +	new_fm->size = sizeof(struct ubi_fm_hdr) + \
> +			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;
> +	new_fm->size = roundup(new_fm->size, ubi->leb_size);
> +
> +	new_fm->used_blocks = new_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);
> +			return -ENOMEM;
> +		}
> +	}
> +
> +	ubi->old_fm = ubi->fm;
> +	ubi->fm = NULL;
> +
> +	spin_lock(&ubi->wl_lock);
> +	new_fm->e[0]->pnum = ubi_wl_get_fm_peb(ubi, UBI_FM_MAX_START);
> +	spin_unlock(&ubi->wl_lock);
> +
> +	if (ubi->old_fm) {
> +		/* no fresh early PEB was found, reuse the old one */
> +		if (new_fm->e[0]->pnum < 0) {
> +			struct ubi_ec_hdr *ec_hdr;
> +
> +			ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
> +			if (!ec_hdr) {
> +				kfree(new_fm);
> +
> +				return -ENOMEM;
> +			}
> +
> +			/* we have to erase the block by hand */
> +
> +			ret = ubi_io_read_ec_hdr(ubi, ubi->old_fm->e[0]->pnum,
> +				ec_hdr, 0);
> +			if (ret) {
> +				ubi_err("Unable to read EC header");
> +				kfree(new_fm);
> +				kfree(ec_hdr);
> +
> +				return ret;
> +			}
> +
> +			ret = ubi_io_sync_erase(ubi, ubi->old_fm->e[0]->pnum,
> +				0);
> +			if (ret < 0) {
> +				ubi_err("Unable to erase old SB");
> +				kfree(new_fm);
> +				kfree(ec_hdr);
> +
> +				return ret;
> +			}
> +
> +			ec_hdr->ec += ret;
> +			if (ec_hdr->ec > UBI_MAX_ERASECOUNTER) {
> +				ubi_err("Erase counter overflow!");
> +				kfree(new_fm);
> +				kfree(ec_hdr);
> +
> +				return -EINVAL;
> +			}
> +
> +			ret = ubi_io_write_ec_hdr(ubi, ubi->old_fm->e[0]->pnum,
> +				ec_hdr);
> +			kfree(ec_hdr);
> +			if (ret) {
> +				ubi_err("Unable to write new EC header");
> +				kfree(new_fm);
> +
> +				return ret;
> +			}
> +
> +			new_fm->e[0]->pnum = ubi->old_fm->e[0]->pnum;
> +			new_fm->e[0]->ec = ubi->old_fm->e[0]->ec;
> +		} else {
> +			/* we've got a new early PEB, return the old one */
> +			ubi_wl_put_fm_peb(ubi, ubi->old_fm->e[0]->pnum, 0);
> +			new_fm->e[0]->ec = get_ec(ubi, new_fm->e[0]->pnum);
> +		}
> +
> +		/* return all other fastmap block to the wl system */
> +		for (i = 1; i < ubi->old_fm->used_blocks; i++)
> +			ubi_wl_put_fm_peb(ubi, ubi->old_fm->e[i]->pnum, 0);

It looks like, if you lose power at this point, the old fastmap may have
been erased but the new fastmap has not been written.  That would mean
you lose the fastmap.  Is that correct?  I guess you need to write the
new fastmap first and then erase the old one.

> +	} else {
> +		if (new_fm->e[0]->pnum < 0) {
> +			ubi_err("Could not find an early PEB");
> +			kfree(new_fm);
> +
> +			return -ENOSPC;
> +		}
> +		new_fm->e[0]->ec = get_ec(ubi, new_fm->e[0]->pnum);
> +	}
> +
> +	if (new_fm->used_blocks > UBI_FM_MAX_BLOCKS) {
> +		ubi_err("Fastmap too large");
> +		kfree(new_fm);
> +
> +		return -ENOSPC;
> +	}
> +
> +	/* give the wl subsystem a chance to produce some free blocks */
> +	cond_resched();
> +
> +	for (i = 1; i < new_fm->used_blocks; i++) {
> +		spin_lock(&ubi->wl_lock);
> +		new_fm->e[i]->pnum = ubi_wl_get_fm_peb(ubi, -1);
> +		spin_unlock(&ubi->wl_lock);
> +
> +		if (new_fm->e[i]->pnum < 0) {
> +			ubi_err("Could not get any free erase block");
> +
> +			while (i--) {
> +				ubi_wl_put_fm_peb(ubi, new_fm->e[i]->pnum, 0);
> +				kfree(new_fm->e[i]);
> +			}
> +
> +			kfree(new_fm);
> +
> +			return -ENOSPC;
> +		}
> +
> +		new_fm->e[i]->ec = get_ec(ubi, new_fm->e[i]->pnum);
> +	}
> +
> +	if (ubi->old_fm) {
> +		for (i = 0; i < ubi->old_fm->used_blocks; i++)
> +			kfree(ubi->old_fm->e[i]);
> +
> +		kfree(ubi->old_fm);
> +		ubi->old_fm = NULL;
> +	}
> +
> +	return ubi_write_fastmap(ubi, new_fm);
> +}
Richard Weinberger - June 1, 2012, 8 a.m.
Am 01.06.2012 07:47, schrieb Adrian Hunter:
> It looks like, if you lose power at this point, the old fastmap may have
> been erased but the new fastmap has not been written.  That would mean
> you lose the fastmap.  Is that correct?  I guess you need to write the
> new fastmap first and then erase the old one.

True. But why is this a problem?
If we can recovers using a full scan after a power cut we are fine.
By deleting the old fastmap after writing the new one we may run out of free PEBs.
E.g: Assume a fastmap needs 4 PEBs and we have only 2 PEBs available the current approach works fine
because after returning and deleting the old fastmap we have 6 PEBs available and can write the new one.

Thanks,
//richard
Artem Bityutskiy - June 1, 2012, 8:10 a.m.
On Fri, 2012-06-01 at 10:00 +0200, Richard Weinberger wrote:
> True. But why is this a problem?
> If we can recovers using a full scan after a power cut we are fine.

Does fastmap have zero power-cut tolerance by design?
Richard Weinberger - June 1, 2012, 8:10 a.m.
Am 01.06.2012 10:10, schrieb Artem Bityutskiy:
> On Fri, 2012-06-01 at 10:00 +0200, Richard Weinberger wrote:
>> True. But why is this a problem?
>> If we can recovers using a full scan after a power cut we are fine.
> 
> Does fastmap have zero power-cut tolerance by design?

Yes.
E.g. If the fastmap was not written corretly the CRC will not match and we fall back
to scanning. That's why fastmap tries hard to fallback to scanning if anything goes wrong.
Why should we make fastmap even more complicated than it already is?

Thanks,
//richard
Adrian Hunter - June 1, 2012, 8:47 a.m.
On 01/06/12 11:10, Richard Weinberger wrote:
> Am 01.06.2012 10:10, schrieb Artem Bityutskiy:
>> On Fri, 2012-06-01 at 10:00 +0200, Richard Weinberger wrote:
>>> True. But why is this a problem?
>>> If we can recovers using a full scan after a power cut we are fine.
>>
>> Does fastmap have zero power-cut tolerance by design?
> 
> Yes.
> E.g. If the fastmap was not written corretly the CRC will not match and we fall back
> to scanning. That's why fastmap tries hard to fallback to scanning if anything goes wrong.
> Why should we make fastmap even more complicated than it already is?

That is fine.  It just needs to be documented so people know what to expect.
i.e. fastmap may not be enough for a use case where power cuts are frequent
and/or long scan times are not acceptable.

Patch

diff --git a/drivers/mtd/ubi/Makefile b/drivers/mtd/ubi/Makefile
index a0803ac..c9f0269 100644
--- a/drivers/mtd/ubi/Makefile
+++ b/drivers/mtd/ubi/Makefile
@@ -1,6 +1,6 @@ 
 obj-$(CONFIG_MTD_UBI) += ubi.o
 
 ubi-y += vtbl.o vmt.o upd.o build.o cdev.o kapi.o eba.o io.o wl.o attach.o
-ubi-y += misc.o debug.o
+ubi-y += fastmap.o misc.o debug.o
 
 obj-$(CONFIG_MTD_UBI_GLUEBI) += gluebi.o
diff --git a/drivers/mtd/ubi/attach.c b/drivers/mtd/ubi/attach.c
index f59f748..23b3d55 100644
--- a/drivers/mtd/ubi/attach.c
+++ b/drivers/mtd/ubi/attach.c
@@ -294,7 +294,7 @@  static struct ubi_ainf_volume *add_volume(struct ubi_attach_info *ai,
 }
 
 /**
- * compare_lebs - find out which logical eraseblock is newer.
+ * ubi_compare_lebs - find out which logical eraseblock is newer.
  * @ubi: UBI device description object
  * @aeb: first logical eraseblock to compare
  * @pnum: physical eraseblock number of the second logical eraseblock to
@@ -313,7 +313,7 @@  static struct ubi_ainf_volume *add_volume(struct ubi_attach_info *ai,
  *     o bit 2 is cleared: the older LEB is not corrupted;
  *     o bit 2 is set: the older LEB is corrupted.
  */
-static int compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
+int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
 			int pnum, const struct ubi_vid_hdr *vid_hdr)
 {
 	void *buf;
@@ -501,7 +501,7 @@  int ubi_add_to_av(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum,
 		 * sequence numbers. We still can attach these images, unless
 		 * there is a need to distinguish between old and new
 		 * eraseblocks, in which case we'll refuse the image in
-		 * 'compare_lebs()'. In other words, we attach old clean
+		 * 'ubi_compare_lebs()'. In other words, we attach old clean
 		 * images, but refuse attaching old images with duplicated
 		 * logical eraseblocks because there was an unclean reboot.
 		 */
@@ -517,7 +517,7 @@  int ubi_add_to_av(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum,
 		 * Now we have to drop the older one and preserve the newer
 		 * one.
 		 */
-		cmp_res = compare_lebs(ubi, aeb, pnum, vid_hdr);
+		cmp_res = ubi_compare_lebs(ubi, aeb, pnum, vid_hdr);
 		if (cmp_res < 0)
 			return cmp_res;
 
@@ -977,7 +977,12 @@  static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
 	}
 
 	vol_id = be32_to_cpu(vidh->vol_id);
-	if (vol_id > UBI_MAX_VOLUMES && vol_id != UBI_LAYOUT_VOLUME_ID) {
+
+	if (vol_id > UBI_MAX_VOLUMES &&
+		vol_id != UBI_LAYOUT_VOLUME_ID &&
+		(ubi->attached_by_scanning ||
+		(vol_id != UBI_FM_SB_VOLUME_ID &&
+		vol_id != UBI_FM_DATA_VOLUME_ID))) {
 		int lnum = be32_to_cpu(vidh->lnum);
 
 		/* Unsupported internal volume */
@@ -1217,11 +1222,20 @@  out_ai:
 int ubi_attach(struct ubi_device *ubi)
 {
 	int err;
-	struct ubi_attach_info *ai;
-
-	ai = scan_all(ubi);
-	if (IS_ERR(ai))
-		return PTR_ERR(ai);
+	struct ubi_attach_info *ai = NULL;
+
+	err = ubi_scan_fastmap(ubi, &ai);
+	if (err > 0) {
+		if (err == UBI_BAD_FASTMAP)
+			ubi_err("Attach by fastmap failed! " \
+				"Falling back to attach by scanning.");
+
+		ubi->attached_by_scanning = 1;
+		ai = scan_all(ubi);
+		if (IS_ERR(ai))
+			return PTR_ERR(ai);
+	} else if (err < 0)
+		return err;
 
 	ubi->bad_peb_count = ai->bad_peb_count;
 	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 2c5ed5c..bd3fa14 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -144,6 +144,18 @@  int ubi_volume_notify(struct ubi_device *ubi, struct ubi_volume *vol, int ntype)
 
 	ubi_do_get_device_info(ubi, &nt.di);
 	ubi_do_get_volume_info(ubi, vol, &nt.vi);
+
+	switch (ntype) {
+	case UBI_VOLUME_ADDED:
+	case UBI_VOLUME_REMOVED:
+	case UBI_VOLUME_RESIZED:
+	case UBI_VOLUME_RENAMED:
+		if (ubi_update_fastmap(ubi)) {
+			ubi_err("Unable to update fastmap!");
+			ubi_ro_mode(ubi);
+		}
+	}
+
 	return blocking_notifier_call_chain(&ubi_notifiers, ntype, &nt);
 }
 
@@ -874,6 +886,19 @@  int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
 	ubi->vid_hdr_offset = vid_hdr_offset;
 	ubi->autoresize_vol_id = -1;
 
+	ubi->fm_pool.used = ubi->fm_pool.size = 0;
+
+	/*
+	 * fm_pool.max_size is 5% of the total number of PEBs but it's also
+	 * between UBI_FM_MAX_POOL_SIZE and UBI_FM_MIN_POOL_SIZE.
+	 */
+	ubi->fm_pool.max_size = min(((int)mtd_div_by_eb(ubi->mtd->size,
+		ubi->mtd) / 100) * 5, UBI_FM_MAX_POOL_SIZE);
+	if (ubi->fm_pool.max_size < UBI_FM_MIN_POOL_SIZE)
+		ubi->fm_pool.max_size = UBI_FM_MIN_POOL_SIZE;
+
+	ubi_msg("fastmap pool size: %d", ubi->fm_pool.max_size);
+
 	mutex_init(&ubi->buf_mutex);
 	mutex_init(&ubi->ckvol_mutex);
 	mutex_init(&ubi->device_mutex);
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 5fa726f..654f121 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -57,7 +57,7 @@ 
  * global sequence counter value. It also increases the global sequence
  * counter.
  */
-static unsigned long long next_sqnum(struct ubi_device *ubi)
+unsigned long long ubi_next_sqnum(struct ubi_device *ubi)
 {
 	unsigned long long sqnum;
 
@@ -522,7 +522,7 @@  retry:
 		goto out_put;
 	}
 
-	vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 	err = ubi_io_write_vid_hdr(ubi, new_pnum, vid_hdr);
 	if (err)
 		goto write_error;
@@ -633,7 +633,7 @@  int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
 	}
 
 	vid_hdr->vol_type = UBI_VID_DYNAMIC;
-	vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 	vid_hdr->vol_id = cpu_to_be32(vol_id);
 	vid_hdr->lnum = cpu_to_be32(lnum);
 	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
@@ -694,7 +694,7 @@  write_error:
 		return err;
 	}
 
-	vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 	ubi_msg("try another PEB");
 	goto retry;
 }
@@ -747,7 +747,7 @@  int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
 		return err;
 	}
 
-	vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 	vid_hdr->vol_id = cpu_to_be32(vol_id);
 	vid_hdr->lnum = cpu_to_be32(lnum);
 	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
@@ -812,7 +812,7 @@  write_error:
 		return err;
 	}
 
-	vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 	ubi_msg("try another PEB");
 	goto retry;
 }
@@ -864,7 +864,7 @@  int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
 	if (err)
 		goto out_mutex;
 
-	vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 	vid_hdr->vol_id = cpu_to_be32(vol_id);
 	vid_hdr->lnum = cpu_to_be32(lnum);
 	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
@@ -932,7 +932,7 @@  write_error:
 		goto out_leb_unlock;
 	}
 
-	vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 	ubi_msg("try another PEB");
 	goto retry;
 }
@@ -1092,7 +1092,7 @@  int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 		vid_hdr->data_size = cpu_to_be32(data_size);
 		vid_hdr->data_crc = cpu_to_be32(crc);
 	}
-	vid_hdr->sqnum = cpu_to_be64(next_sqnum(ubi));
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
 
 	err = ubi_io_write_vid_hdr(ubi, to, vid_hdr);
 	if (err) {
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
new file mode 100644
index 0000000..7757e5a
--- /dev/null
+++ b/drivers/mtd/ubi/fastmap.c
@@ -0,0 +1,1240 @@ 
+/*
+ * 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; either version 2 of the License.
+ *
+ * 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"
+
+/**
+ * new_fm_vhdr - allocate a new volume header for fastmap usage.
+ * @ubi: UBI device description object
+ * @vol_id: the VID of the new header
+ */
+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
+ */
+static int add_aeb(struct ubi_attach_info *ai, struct list_head *list,
+		   int pnum, int ec)
+{
+	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 = 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 scan 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
+ */
+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
+ */
+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) {
+			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\n",
+				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;
+			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\n",
+				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
+ */
+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);
+}
+
+/**
+ * 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
+ */
+static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai,
+	int *pebs, int pool_size, unsigned long long *max_sqnum)
+{
+	struct ubi_vid_hdr *vh;
+	struct ubi_ec_hdr *ech;
+	struct ubi_ainf_peb *new_aeb;
+	int i;
+	int pnum;
+	int err;
+	int 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++) {
+		pnum = be32_to_cpu(pebs[i]);
+
+		if (ubi_io_is_bad(ubi, pnum)) {
+			dbg_bld("Bad PEB in fastmap pool!");
+			ret = UBI_BAD_FASTMAP;
+
+			goto out;
+		}
+
+		err = ubi_io_read_vid_hdr(ubi, pnum, vh, 0);
+
+		if (err == UBI_IO_FF)
+			continue;
+		else if (err == 0) {
+			err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+			if (err) {
+				dbg_bld("Unable to read EC header!");
+				ret = err > 0 ? UBI_BAD_FASTMAP : err;
+
+				goto out;
+			}
+
+			if (be32_to_cpu(ech->image_seq) != ubi->image_seq) {
+				dbg_bld("Image seq mismatch!");
+				err = UBI_BAD_FASTMAP;
+
+				goto out;
+			}
+
+			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 = 0;
+
+			err = process_pool_aeb(ubi, ai, vh, new_aeb);
+			if (err) {
+				ret = err > 0 ? UBI_BAD_FASTMAP : err;
+
+				goto out;
+			}
+
+			if (*max_sqnum < new_aeb->sqnum)
+				*max_sqnum = new_aeb->sqnum;
+		} 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;
+}
+
+/**
+ * ubi_attach_fastmap - creates ubi_attach_info from a fastmap.
+ * @ubi: UBI device object
+ * @fm_raw: the fastmap it self as byte array
+ * @fm_size: size of the fastmap in bytes
+ */
+static int ubi_attach_fastmap(struct ubi_device *ubi,
+			      struct ubi_attach_info **aip,
+			      char *fm_raw, size_t fm_size)
+{
+	struct list_head used;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb, *tmp_aeb, *_tmp_aeb;
+	struct ubi_attach_info *ai;
+
+	struct ubi_fm_sb *fmsb;
+	struct ubi_fm_hdr *fmhdr;
+	struct ubi_fm_scan_pool *fmpl;
+	struct ubi_fm_ec *fmec;
+	struct ubi_fm_volhdr *fmvhdr;
+	struct ubi_fm_eba *fm_eba;
+
+	int ret, i, j;
+	size_t fm_pos = 0;
+	unsigned long long max_sqnum = 0;
+
+	*aip = kzalloc(sizeof(struct ubi_attach_info), GFP_KERNEL);
+	if (!*aip)
+		return -ENOMEM;
+
+	ai = *aip;
+
+	INIT_LIST_HEAD(&used);
+	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 (fmhdr->magic != UBI_FM_HDR_MAGIC)
+		goto fail_bad;
+
+	fmpl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+	if (fmpl->magic != UBI_FM_POOL_MAGIC)
+		goto fail_bad;
+
+	/* read EC values from free list */
+	for (i = 0; i < be32_to_cpu(fmhdr->nfree); 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));
+	}
+
+	/* read EC values from used list */
+	for (i = 0; i < be32_to_cpu(fmhdr->nused); 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));
+	}
+
+	ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
+	ai->bad_peb_count = be32_to_cpu(fmhdr->nbad);
+
+	/* Iterate over all volumes and read their EBA table */
+	for (i = 0; i < be32_to_cpu(fmhdr->nvol); i++) {
+		fmvhdr = (struct ubi_fm_volhdr *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmvhdr);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		if (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->nused));
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		if (fm_eba->magic != UBI_FM_EBA_MAGIC)
+			goto fail_bad;
+
+		for (j = 0; j < be32_to_cpu(fm_eba->nused); 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 == \
+					be32_to_cpu(fm_eba->pnum[j]))
+					aeb = tmp_aeb;
+			}
+
+			/* Corner case, this PEB must be in the pool */
+			if (!aeb)
+				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);
+		}
+	}
+
+	/*
+	 * The remainning PEB in the used list are not used.
+	 * They lived in the fastmap pool but got never used.
+	 */
+	list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &used, u.list) {
+		list_del(&tmp_aeb->u.list);
+		list_add_tail(&tmp_aeb->u.list, &ai->free);
+	}
+
+	ret = scan_pool(ubi, ai, fmpl->pebs, be32_to_cpu(fmpl->size),
+		&max_sqnum);
+	if (ret)
+		goto fail;
+
+
+	if (max_sqnum > ai->max_sqnum)
+		ai->max_sqnum = max_sqnum;
+
+	return 0;
+
+fail_bad:
+	ret = UBI_BAD_FASTMAP;
+fail:
+	ubi_destroy_ai(ai);
+	return ret;
+}
+
+/**
+ * ubi_find_fastmap - searches the first UBI_FM_MAX_START PEBs for the
+ * fastmap super block.
+ * @ubi: UBI device object
+ */
+static int ubi_find_fastmap(struct ubi_device *ubi, int *fm_start)
+{
+	int i, ret;
+	struct ubi_vid_hdr *vhdr;
+
+	vhdr = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+	if (!vhdr)
+		return -ENOMEM;
+
+	for (i = 0; i < UBI_FM_MAX_START; i++) {
+		ret = ubi_io_read_vid_hdr(ubi, i, vhdr, 0);
+		if (ret < 0)
+			break;
+		else if (ret > 0)
+			continue;
+
+		if (be32_to_cpu(vhdr->vol_id) == UBI_FM_SB_VOLUME_ID) {
+			*fm_start = i;
+			dbg_bld("Found fastmap super block at PEB %i\n", i);
+			ret = 0;
+
+			break;
+		}
+	}
+
+	ubi_free_vid_hdr(ubi, vhdr);
+
+	return ret;
+}
+
+/**
+ * ubi_scan_fastmap - scan the fastmap
+ * @ubi: UBI device object
+ * @ai: UBI attach info to be filled
+ */
+int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info **ai)
+{
+	struct ubi_fm_sb *fmsb;
+	struct ubi_vid_hdr *vh;
+	struct ubi_ec_hdr *ech;
+	int ret, i, nblocks, pnum;
+	int sb_pnum = 0;
+	char *fm_raw;
+	size_t fm_size;
+	__be32 crc, tmp_crc;
+	unsigned long long sqnum = 0;
+
+	ret = ubi_find_fastmap(ubi, &sb_pnum);
+	if (ret) {
+		if (ret > 0)
+			ret = UBI_NO_FASTMAP;
+
+		goto out;
+	}
+
+	fmsb = kmalloc(sizeof(*fmsb), GFP_KERNEL);
+	if (!fmsb) {
+		ret = -ENOMEM;
+
+		goto out;
+	}
+
+	ret = ubi_io_read(ubi, fmsb, sb_pnum, ubi->leb_start, sizeof(*fmsb));
+	if (ret) {
+		ubi_err("Unable to read fastmap super block");
+		if (ret > 0)
+			ret = UBI_BAD_FASTMAP;
+
+		kfree(fmsb);
+
+		goto out;
+	}
+
+	if (fmsb->magic != UBI_FM_SB_MAGIC) {
+		ubi_err("Super block magic does not match");
+		ret = UBI_BAD_FASTMAP;
+		kfree(fmsb);
+
+		goto out;
+	}
+
+	if (fmsb->version != UBI_FM_FMT_VERSION) {
+		ubi_err("Unknown fastmap format version!");
+		ret = UBI_BAD_FASTMAP;
+		kfree(fmsb);
+
+		goto out;
+	}
+
+	nblocks = be32_to_cpu(fmsb->nblocks);
+
+	if (nblocks > UBI_FM_MAX_BLOCKS || nblocks < 1) {
+		ubi_err("Number of fastmap blocks is invalid");
+		ret = UBI_BAD_FASTMAP;
+		kfree(fmsb);
+
+		goto out;
+	}
+
+	fm_size = ubi->leb_size * nblocks;
+	/* fm_raw will contain the whole fastmap */
+	fm_raw = vzalloc(fm_size);
+	if (!fm_raw) {
+		ret = -ENOMEM;
+		kfree(fmsb);
+
+		goto out;
+	}
+
+	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ech) {
+		ret = -ENOMEM;
+		kfree(fmsb);
+
+		goto free_raw;
+	}
+
+	vh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
+	if (!vh) {
+		ret = -ENOMEM;
+		kfree(fmsb);
+		kfree(ech);
+
+		goto free_raw;
+	}
+
+	for (i = 0; i < nblocks; i++) {
+		pnum = be32_to_cpu(fmsb->block_loc[i]);
+
+		if (ubi_io_is_bad(ubi, pnum)) {
+			ret = UBI_BAD_FASTMAP;
+			kfree(fmsb);
+
+			goto free_hdr;
+		}
+
+		ret = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+		if (ret) {
+			ubi_err("Unable to read fastmap block# %i EC (PEB: %i)",
+				i, pnum);
+			if (ret > 0)
+				ret = UBI_BAD_FASTMAP;
+			kfree(fmsb);
+
+			goto free_hdr;
+		}
+
+		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);
+
+			goto free_hdr;
+		}
+
+		ret = ubi_io_read_vid_hdr(ubi, pnum, vh, 0);
+		if (ret) {
+			ubi_err("Unable to read fastmap block# %i (PEB: %i)",
+				i, pnum);
+			if (ret > 0)
+				ret = UBI_BAD_FASTMAP;
+			kfree(fmsb);
+
+			goto free_hdr;
+		}
+
+		if (i == 0) {
+			if (be32_to_cpu(vh->vol_id) != UBI_FM_SB_VOLUME_ID) {
+				ret = UBI_BAD_FASTMAP;
+				kfree(fmsb);
+
+				goto free_hdr;
+			}
+		} else {
+			if (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, fm_raw + (ubi->leb_size * i), pnum,
+			ubi->leb_start, ubi->leb_size);
+
+		if (ret) {
+			ubi_err("Unable to read fastmap block# %i (PEB: %i)",
+				i, pnum);
+			if (ret > 0)
+				ret = UBI_BAD_FASTMAP;
+			kfree(fmsb);
+
+			goto free_hdr;
+		}
+	}
+
+	kfree(fmsb);
+
+	fmsb = (struct ubi_fm_sb *)fm_raw;
+	tmp_crc = fmsb->data_crc;
+	fmsb->data_crc = 0;
+	crc = crc32_be(UBI_CRC32_INIT, fm_raw, fm_size);
+	if (crc != tmp_crc) {
+		ubi_err("Fastmap data CRC is invalid");
+		ret = UBI_BAD_FASTMAP;
+
+		goto free_hdr;
+	}
+
+	fmsb->sqnum = sqnum;
+
+	ret = ubi_attach_fastmap(ubi, ai, fm_raw, fm_size);
+	if (ret) {
+		if (ret > 0)
+			ret = UBI_BAD_FASTMAP;
+		ubi_destroy_ai(*ai);
+
+		goto free_hdr;
+	}
+
+	/* Store the fastmap position into the ubi_device struct */
+	ubi->fm = kmalloc(sizeof(*ubi->fm), GFP_KERNEL);
+	if (!ubi->fm) {
+		ret = -ENOMEM;
+
+		goto free_hdr;
+	}
+
+	ubi->fm->size = fm_size;
+	ubi->fm->used_blocks = nblocks;
+
+	for (i = 0; i < nblocks; i++) {
+		ubi->fm->e[i] = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+		if (!ubi->fm->e[i]) {
+			while (i--)
+				kfree(ubi->fm->e[i]);
+
+			kfree(ubi->fm);
+			ret = -ENOMEM;
+			goto free_hdr;
+		}
+	}
+
+	for (i = 0; i < UBI_FM_MAX_BLOCKS; i++) {
+		if (i < nblocks) {
+			ubi->fm->e[i]->pnum = be32_to_cpu(fmsb->block_loc[i]);
+			ubi->fm->e[i]->ec = be32_to_cpu(fmsb->block_ec[i]);
+		} else
+			ubi->fm->e[i] = NULL;
+	}
+
+free_hdr:
+	ubi_free_vid_hdr(ubi, vh);
+	kfree(ech);
+free_raw:
+	vfree(fm_raw);
+out:
+	return ret;
+}
+
+/**
+ * ubi_write_fastmap - writes a fastmap
+ * @ubi: UBI device object
+ * @new_fm: the to be written fastmap
+ */
+static int ubi_write_fastmap(struct ubi_device *ubi,
+			     struct ubi_fastmap_layout *new_fm)
+{
+	int ret;
+	size_t fm_pos = 0;
+	char *fm_raw;
+	int i, j;
+
+	struct ubi_fm_sb *fmsb;
+	struct ubi_fm_hdr *fmh;
+	struct ubi_fm_scan_pool *fmpl;
+	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;
+
+	int nfree, nused, nvol;
+
+	fm_raw = vzalloc(new_fm->size);
+	if (!fm_raw) {
+		ret = -ENOMEM;
+
+		goto out;
+	}
+
+	avhdr = new_fm_vhdr(ubi, UBI_FM_SB_VOLUME_ID);
+	if (!avhdr) {
+		ret = -ENOMEM;
+
+		goto out_vfree;
+	}
+
+	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 <= new_fm->size);
+
+	fmh = (struct ubi_fm_hdr *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmh);
+	ubi_assert(fm_pos <= new_fm->size);
+
+	fmsb->magic = UBI_FM_SB_MAGIC;
+	fmsb->version = UBI_FM_FMT_VERSION;
+	fmsb->nblocks = cpu_to_be32(new_fm->used_blocks);
+	/* the max sqnum will be filled in while *reading* the fastmap */
+	fmsb->sqnum = 0;
+
+	fmh->magic = UBI_FM_HDR_MAGIC;
+	nfree = 0;
+	nused = 0;
+	nvol = 0;
+
+	fmpl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl);
+	fmpl->magic = UBI_FM_POOL_MAGIC;
+	fmpl->size = cpu_to_be32(ubi->fm_pool.size);
+
+	for (i = 0; i < ubi->fm_pool.size; i++)
+		fmpl->pebs[i] = cpu_to_be32(ubi->fm_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);
+
+		nfree++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= new_fm->size);
+	}
+	fmh->nfree = cpu_to_be32(nfree);
+
+	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);
+
+		nused++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= new_fm->size);
+	}
+	fmh->nused = cpu_to_be32(nused);
+
+	for (i = 0; i < UBI_MAX_VOLUMES + UBI_INT_VOL_COUNT; i++) {
+		vol = ubi->volumes[i];
+
+		if (!vol)
+			continue;
+
+		nvol++;
+
+		fvh = (struct ubi_fm_volhdr *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fvh);
+		ubi_assert(fm_pos <= new_fm->size);
+
+		fvh->magic = 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->used_ebs);
+		ubi_assert(fm_pos <= new_fm->size);
+
+		for (j = 0; j < vol->used_ebs; j++)
+			feba->pnum[j] = cpu_to_be32(vol->eba_tbl[j]);
+
+		feba->nused = cpu_to_be32(j);
+		feba->magic = UBI_FM_EBA_MAGIC;
+	}
+	fmh->nvol = cpu_to_be32(nvol);
+
+	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\n", 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!\n");
+
+		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 = crc32_be(UBI_CRC32_INIT, fm_raw, new_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\n",
+			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!\n",
+				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!\n",
+				new_fm->e[i]->pnum);
+
+			goto out_kfree;
+		}
+	}
+
+	ubi_assert(new_fm);
+	ubi->fm = new_fm;
+
+	dbg_bld("Fastmap written!");
+
+out_kfree:
+	kfree(avhdr);
+out_vfree:
+	vfree(fm_raw);
+out:
+	return ret;
+}
+
+/**
+ * get_ec - returns the erase counter of a given PEB
+ * @ubi: UBI device object
+ * @pnum: PEB number
+ */
+static int get_ec(struct ubi_device *ubi, int pnum)
+{
+	struct ubi_wl_entry *e;
+
+	e = ubi->lookuptbl[pnum];
+
+	/* can this really happen? */
+	if (!e)
+		return ubi->mean_ec ?: 1;
+	else
+		return e->ec;
+}
+
+/**
+ * ubi_update_fastmap - will be called by UBI if a volume changes or
+ * a fastmap pool becomes full.
+ * @ubi: UBI device object
+ */
+int ubi_update_fastmap(struct ubi_device *ubi)
+{
+	int ret, i;
+	struct ubi_fastmap_layout *new_fm;
+
+	if (ubi->ro_mode)
+		return 0;
+
+	new_fm = kzalloc(sizeof(*new_fm), GFP_KERNEL);
+	if (!new_fm)
+		return -ENOMEM;
+
+	new_fm->size = sizeof(struct ubi_fm_hdr) + \
+			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;
+	new_fm->size = roundup(new_fm->size, ubi->leb_size);
+
+	new_fm->used_blocks = new_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);
+			return -ENOMEM;
+		}
+	}
+
+	ubi->old_fm = ubi->fm;
+	ubi->fm = NULL;
+
+	spin_lock(&ubi->wl_lock);
+	new_fm->e[0]->pnum = ubi_wl_get_fm_peb(ubi, UBI_FM_MAX_START);
+	spin_unlock(&ubi->wl_lock);
+
+	if (ubi->old_fm) {
+		/* no fresh early PEB was found, reuse the old one */
+		if (new_fm->e[0]->pnum < 0) {
+			struct ubi_ec_hdr *ec_hdr;
+
+			ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+			if (!ec_hdr) {
+				kfree(new_fm);
+
+				return -ENOMEM;
+			}
+
+			/* we have to erase the block by hand */
+
+			ret = ubi_io_read_ec_hdr(ubi, ubi->old_fm->e[0]->pnum,
+				ec_hdr, 0);
+			if (ret) {
+				ubi_err("Unable to read EC header");
+				kfree(new_fm);
+				kfree(ec_hdr);
+
+				return ret;
+			}
+
+			ret = ubi_io_sync_erase(ubi, ubi->old_fm->e[0]->pnum,
+				0);
+			if (ret < 0) {
+				ubi_err("Unable to erase old SB");
+				kfree(new_fm);
+				kfree(ec_hdr);
+
+				return ret;
+			}
+
+			ec_hdr->ec += ret;
+			if (ec_hdr->ec > UBI_MAX_ERASECOUNTER) {
+				ubi_err("Erase counter overflow!");
+				kfree(new_fm);
+				kfree(ec_hdr);
+
+				return -EINVAL;
+			}
+
+			ret = ubi_io_write_ec_hdr(ubi, ubi->old_fm->e[0]->pnum,
+				ec_hdr);
+			kfree(ec_hdr);
+			if (ret) {
+				ubi_err("Unable to write new EC header");
+				kfree(new_fm);
+
+				return ret;
+			}
+
+			new_fm->e[0]->pnum = ubi->old_fm->e[0]->pnum;
+			new_fm->e[0]->ec = ubi->old_fm->e[0]->ec;
+		} else {
+			/* we've got a new early PEB, return the old one */
+			ubi_wl_put_fm_peb(ubi, ubi->old_fm->e[0]->pnum, 0);
+			new_fm->e[0]->ec = get_ec(ubi, new_fm->e[0]->pnum);
+		}
+
+		/* return all other fastmap block to the wl system */
+		for (i = 1; i < ubi->old_fm->used_blocks; i++)
+			ubi_wl_put_fm_peb(ubi, ubi->old_fm->e[i]->pnum, 0);
+	} else {
+		if (new_fm->e[0]->pnum < 0) {
+			ubi_err("Could not find an early PEB");
+			kfree(new_fm);
+
+			return -ENOSPC;
+		}
+		new_fm->e[0]->ec = get_ec(ubi, new_fm->e[0]->pnum);
+	}
+
+	if (new_fm->used_blocks > UBI_FM_MAX_BLOCKS) {
+		ubi_err("Fastmap too large");
+		kfree(new_fm);
+
+		return -ENOSPC;
+	}
+
+	/* give the wl subsystem a chance to produce some free blocks */
+	cond_resched();
+
+	for (i = 1; i < new_fm->used_blocks; i++) {
+		spin_lock(&ubi->wl_lock);
+		new_fm->e[i]->pnum = ubi_wl_get_fm_peb(ubi, -1);
+		spin_unlock(&ubi->wl_lock);
+
+		if (new_fm->e[i]->pnum < 0) {
+			ubi_err("Could not get any free erase block");
+
+			while (i--) {
+				ubi_wl_put_fm_peb(ubi, new_fm->e[i]->pnum, 0);
+				kfree(new_fm->e[i]);
+			}
+
+			kfree(new_fm);
+
+			return -ENOSPC;
+		}
+
+		new_fm->e[i]->ec = get_ec(ubi, new_fm->e[i]->pnum);
+	}
+
+	if (ubi->old_fm) {
+		for (i = 0; i < ubi->old_fm->used_blocks; i++)
+			kfree(ubi->old_fm->e[i]);
+
+		kfree(ubi->old_fm);
+		ubi->old_fm = NULL;
+	}
+
+	return ubi_write_fastmap(ubi, new_fm);
+}
diff --git a/drivers/mtd/ubi/ubi-media.h b/drivers/mtd/ubi/ubi-media.h
index 468ffbc..0e3019a 100644
--- a/drivers/mtd/ubi/ubi-media.h
+++ b/drivers/mtd/ubi/ubi-media.h
@@ -375,4 +375,123 @@  struct ubi_vtbl_record {
 	__be32  crc;
 } __packed;
 
+/* UBI fastmap on-flash data structures */
+
+#define UBI_FM_SB_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 1)
+#define UBI_FM_DATA_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 2)
+
+/* fastmap on-flash data structure format version */
+#define UBI_FM_FMT_VERSION	1
+
+#define UBI_FM_SB_MAGIC		0x7B11D69F
+#define UBI_FM_HDR_MAGIC	0xD4B82EF7
+#define UBI_FM_VHDR_MAGIC	0xFA370ED1
+#define UBI_FM_POOL_MAGIC	0x67AF4D08
+#define UBI_FM_EBA_MAGIC	0xf0c040a8
+
+#define UBI_FM_MAX_START	64
+#define UBI_FM_MAX_BLOCKS	32
+#define UBI_FM_MIN_POOL_SIZE	8
+#define UBI_FM_MAX_POOL_SIZE	256
+
+/**
+ * struct ubi_fm_sb - UBI fastmap super block
+ * @magic: fastmap super block magic number (%UBI_FM_SB_MAGIC)
+ * @version: format version of this fastmap
+ * @data_crc: CRC over the fastmap data
+ * @nblocks: number of PEBs used by this fastmap
+ * @block_loc: an array containing the location of all PEBs of the fastmap
+ * @block_ec: the erase counter of each used PEB
+ * @sqnum: highest sequence number value at the time while taking the fastmap
+ *
+ */
+struct ubi_fm_sb {
+	__be32 magic;
+	__u8 version;
+	__u8 padding1[3];
+	__be32 data_crc;
+	__be32 nblocks;
+	__be32 block_loc[UBI_FM_MAX_BLOCKS];
+	__be32 block_ec[UBI_FM_MAX_BLOCKS];
+	__be64 sqnum;
+	__u8 padding2[32];
+} __packed;
+
+/**
+ * struct ubi_fm_hdr - header of the fastmap data set
+ * @magic: fastmap header magic number (%UBI_FM_HDR_MAGIC)
+ * @nfree: number of free PEBs known by this fastmap
+ * @nused: number of used PEBs known by this fastmap
+ * @nvol: number of UBI volumes known by this fastmap
+ */
+struct ubi_fm_hdr {
+	__be32 magic;
+	__be32 nfree;
+	__be32 nused;
+	__be32 nvol;
+	__be32 nbad;
+	__u8 padding[12];
+} __packed;
+
+/* struct ubi_fm_hdr is followed by struct ubi_fm_scan_pool */
+
+/**
+ * struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
+ * @magic: pool magic numer (%UBI_FM_POOL_MAGIC)
+ * @size: current pool size
+ * @pebs: an array containing the location of all PEBs in this pool
+ */
+struct ubi_fm_scan_pool {
+	__be32 magic;
+	__be32 size;
+	__be32 pebs[UBI_FM_MAX_POOL_SIZE];
+	__be32 padding[4];
+} __packed;
+
+/* ubi_fm_scan_pool is followed by nfree+nused struct ubi_fm_ec records */
+
+/**
+ * struct ubi_fm_ec - stores the erase counter of a PEB
+ * @pnum: PEB number
+ * @ec: ec of this PEB
+ */
+struct ubi_fm_ec {
+	__be32 pnum;
+	__be32 ec;
+} __packed;
+
+/**
+ * struct ubi_fm_volhdr - Fastmap volume header
+ * it identifies the start of an eba table
+ * @magic: Fastmap volume header magic number (%UBI_FM_VHDR_MAGIC)
+ * @vol_id: volume id of the fastmapped volume
+ * @vol_type: type of the fastmapped volume
+ * @data_pad: data_pad value of the fastmapped volume
+ * @used_ebs: number of used LEBs within this volume
+ * @last_eb_bytes: number of bytes used in the last LEB
+ */
+struct ubi_fm_volhdr {
+	__be32 magic;
+	__be32 vol_id;
+	__u8 vol_type;
+	__u8 padding1[3];
+	__be32 data_pad;
+	__be32 used_ebs;
+	__be32 last_eb_bytes;
+	__u8 padding2[8];
+} __packed;
+
+/* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
+
+/**
+ * struct ubi_fm_eba - denotes an association beween a PEB and LEB
+ * @magic EBA table magic number
+ * @nused: number of table entries
+ * @pnum: PEB number of LEB (LEB is the index)
+ */
+struct ubi_fm_eba {
+	__be32 magic;
+	__be32 nused;
+	__be32 pnum[0];
+} __packed;
 #endif /* !__UBI_MEDIA_H__ */
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 5275632..e5fe951 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -136,6 +136,17 @@  enum {
 	MOVE_RETRY,
 };
 
+/*
+ * Return codes of the fastmap sub-system
+ *
+ * UBI_NO_FASTMAP: No fastmap super block was found
+ * UBI_BAD_FASTMAP: A fastmap was found but it's unusable
+ */
+enum {
+	UBI_NO_FASTMAP = 1,
+	UBI_BAD_FASTMAP,
+};
+
 /**
  * struct ubi_wl_entry - wear-leveling entry.
  * @u.rb: link in the corresponding (free/used) RB-tree
@@ -202,6 +213,38 @@  struct ubi_rename_entry {
 struct ubi_volume_desc;
 
 /**
+ * struct ubi_fastmap_layout - in-memory fastmap data structure.
+ * @peb: PEBs used by the current fastmap
+ * @ec: the erase counter of each used PEB
+ * @size: size of the fastmap in bytes
+ * @used_blocks: number of used PEBs
+ */
+struct ubi_fastmap_layout {
+	struct ubi_wl_entry *e[UBI_FM_MAX_BLOCKS];
+	size_t size;
+	int used_blocks;
+};
+
+/**
+ * struct ubi_fm_pool - in-memory fastmap pool
+ * @pebs: PEBs in this pool
+ * @used: number of used PEBs
+ * @size: total number of PEBs in this pool
+ * @max_size: maximal size of the pool
+ *
+ * A pool gets filled with up to max_size.
+ * If all PEBs within the pool are used a new fastmap will be written
+ * to the flash and the pool gets refilled with empty PEBs.
+ *
+ */
+struct ubi_fm_pool {
+	int pebs[UBI_FM_MAX_POOL_SIZE];
+	int used;
+	int size;
+	int max_size;
+};
+
+/**
  * struct ubi_volume - UBI volume description data structure.
  * @dev: device object to make use of the the Linux device model
  * @cdev: character device object to create character device
@@ -336,6 +379,13 @@  struct ubi_wl_entry;
  * @ltree: the lock tree
  * @alc_mutex: serializes "atomic LEB change" operations
  *
+ * @fm: in-memory data structure of the currently used fastmap
+ * @old_fm: in-memory data structure old fastmap.
+ *	    (only valid while writing a new one)
+ * @fm_pool: in-memory data structure of the fastmap pool
+ * @attached_by_scanning: this UBI device was attached by the old scanning
+ *			  methold. All fastmap volumes have to be deleted.
+ *
  * @used: RB-tree of used physical eraseblocks
  * @erroneous: RB-tree of erroneous used physical eraseblocks
  * @free: RB-tree of free physical eraseblocks
@@ -427,6 +477,12 @@  struct ubi_device {
 	struct rb_root ltree;
 	struct mutex alc_mutex;
 
+	/* Fastmap stuff */
+	struct ubi_fastmap_layout *fm;
+	struct ubi_fastmap_layout *old_fm;
+	struct ubi_fm_pool fm_pool;
+	int attached_by_scanning;
+
 	/* Wear-leveling sub-system's stuff */
 	struct rb_root used;
 	struct rb_root erroneous;
@@ -604,7 +660,7 @@  extern struct class *ubi_class;
 extern struct mutex ubi_devices_mutex;
 extern struct blocking_notifier_head ubi_notifiers;
 
-/* scan.c */
+/* attach.c */
 int ubi_add_to_av(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum,
 		  int ec, const struct ubi_vid_hdr *vid_hdr, int bitflips);
 struct ubi_ainf_volume *ubi_find_av(const struct ubi_attach_info *ai,
@@ -661,6 +717,7 @@  int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
 int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 		     struct ubi_vid_hdr *vid_hdr);
 int ubi_eba_init(struct ubi_device *ubi, struct ubi_attach_info *ai);
+unsigned long long ubi_next_sqnum(struct ubi_device *ubi);
 
 /* wl.c */
 int ubi_wl_get_peb(struct ubi_device *ubi);
@@ -670,6 +727,8 @@  int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum);
 int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai);
 void ubi_wl_close(struct ubi_device *ubi);
 int ubi_thread(void *u);
+int ubi_wl_get_fm_peb(struct ubi_device *ubi, int max_pnum);
+int ubi_wl_put_fm_peb(struct ubi_device *ubi, int pnum, int torture);
 
 /* io.c */
 int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
@@ -706,6 +765,13 @@  void ubi_free_internal_volumes(struct ubi_device *ubi);
 void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di);
 void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
 			    struct ubi_volume_info *vi);
+/* scan.c */
+int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
+		      int pnum, const struct ubi_vid_hdr *vid_hdr);
+
+/* fastmap.c */
+int ubi_update_fastmap(struct ubi_device *ubi);
+int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info **ai);
 
 /*
  * ubi_rb_for_each_entry - walk an RB-tree.
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index c143e61..7d34495 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -162,6 +162,25 @@  static int self_check_in_pq(const struct ubi_device *ubi,
 			    struct ubi_wl_entry *e);
 
 /**
+ *  ubi_ubi_is_fm_block - returns 1 if a PEB is currently used in a fastmap.
+ *  @ubi: UBI device description object
+ *  @pnum: the to be checked PEB
+ */
+int ubi_is_fm_block(struct ubi_device *ubi, int pnum)
+{
+	int i;
+
+	if (!ubi->fm)
+		return 0;
+
+	for (i = 0; i < ubi->fm->used_blocks; i++)
+		if (ubi->fm->e[i]->pnum == pnum)
+			return 1;
+
+	return 0;
+}
+
+/**
  * wl_tree_add - add a wear-leveling entry to a WL RB-tree.
  * @e: the wear-leveling entry to add
  * @root: the root of the tree
@@ -367,13 +386,82 @@  static struct ubi_wl_entry *find_wl_entry(struct rb_root *root, int diff)
 }
 
 /**
- * ubi_wl_get_peb - get a physical eraseblock.
+ * find_early_wl_entry - find wear-leveling entry with the lowest pnum.
+ * @root: the RB-tree where to look for
+ * @max_pnum: highest possible pnum
+ */
+static struct ubi_wl_entry *find_early_wl_entry(struct rb_root *root,
+						int max_pnum)
+{
+	struct rb_node *p;
+	struct ubi_wl_entry *e, *victim = NULL;
+
+	ubi_rb_for_each_entry(p, e, root, u.rb) {
+		if (e->pnum < max_pnum) {
+			victim = e;
+			max_pnum = e->pnum;
+		}
+	}
+
+	return victim;
+}
+
+/**
+ * ubi_wl_get_fm_peb - find a physical erase block with a given maximal number.
+ * @ubi: UBI device description object
+ * @max_pnum: the highest acceptable erase block number
+ *
+ * The function returns a physical erase block with a given maximal number
+ * and removes it from the wl subsystem.
+ * If max_pnum is negative a PEB with a mean EC will be selected.
+ * Must be called with wl_lock held!
+ */
+int ubi_wl_get_fm_peb(struct ubi_device *ubi, int max_pnum)
+{
+	int ret = -ENOSPC;
+	struct ubi_wl_entry *e, *first, *last;
+
+	if (!ubi->free.rb_node) {
+		ubi_err("no free eraseblocks");
+
+		goto out;
+	}
+
+	if (max_pnum < 0) {
+		first = rb_entry(rb_first(&ubi->free),
+			struct ubi_wl_entry, u.rb);
+		last = rb_entry(rb_last(&ubi->free),
+			struct ubi_wl_entry, u.rb);
+
+		if (last->ec - first->ec < WL_FREE_MAX_DIFF)
+			e = rb_entry(ubi->free.rb_node,
+				struct ubi_wl_entry, u.rb);
+		else
+			e = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF/2);
+	} else
+		e = find_early_wl_entry(&ubi->free, max_pnum);
+
+	if (!e)
+		goto out;
+
+	self_check_in_wl_tree(ubi, e, &ubi->free);
+	ret = e->pnum;
+
+	/* remove it from the free list,
+	 * the wl subsystem does no longer know this erase block */
+	rb_erase(&e->u.rb, &ubi->free);
+out:
+	return ret;
+}
+
+/**
+ * __ubi_wl_get_peb - get a physical eraseblock.
  * @ubi: UBI device description object
  *
  * This function returns a physical eraseblock in case of success and a
  * negative error code in case of failure. Might sleep.
  */
-int ubi_wl_get_peb(struct ubi_device *ubi)
+static int __ubi_wl_get_peb(struct ubi_device *ubi)
 {
 	int err;
 	struct ubi_wl_entry *e, *first, *last;
@@ -424,6 +512,40 @@  retry:
 	return e->pnum;
 }
 
+/* ubi_wl_get_peb - works exaclty like __ubi_wl_get_peb but keeps track of
+ * the fastmap pool.
+ */
+int ubi_wl_get_peb(struct ubi_device *ubi)
+{
+	struct ubi_fm_pool *pool = &ubi->fm_pool;
+	int ret;
+
+	/* pool contains no free blocks, create a new one
+	 * and write a fastmap */
+	if (pool->used == pool->size || !pool->size) {
+		for (pool->size = 0; pool->size < pool->max_size;
+				pool->size++) {
+			pool->pebs[pool->size] = __ubi_wl_get_peb(ubi);
+			if (pool->pebs[pool->size] < 0)
+				break;
+		}
+
+		pool->used = 0;
+		ret = ubi_update_fastmap(ubi);
+		if (ret) {
+			ubi_ro_mode(ubi);
+
+			return ret > 0 ? -EINVAL : ret;
+		}
+	}
+
+	/* we got not a single free PEB */
+	if (!pool->size)
+		return -ENOSPC;
+
+	return pool->pebs[pool->used++];
+}
+
 /**
  * prot_queue_del - remove a physical eraseblock from the protection queue.
  * @ubi: UBI device description object
@@ -589,6 +711,9 @@  static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
 {
 	struct ubi_work *wl_wrk;
 
+	ubi_assert(e);
+	ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
+
 	dbg_wl("schedule erasure of PEB %d, EC %d, torture %d",
 	       e->pnum, e->ec, torture);
 
@@ -605,6 +730,52 @@  static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
 }
 
 /**
+ * ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
+ * sub-system.
+ *
+ * see: ubi_wl_put_peb()
+ */
+int ubi_wl_put_fm_peb(struct ubi_device *ubi, int pnum, int torture)
+{
+	int i, err = 0;
+	struct ubi_wl_entry *e;
+
+	dbg_wl("PEB %d", pnum);
+	ubi_assert(pnum >= 0);
+	ubi_assert(pnum < ubi->peb_count);
+
+	spin_lock(&ubi->wl_lock);
+	e = ubi->lookuptbl[pnum];
+
+	/* This can happen if we recovered from a fastmap the very
+	 * first time and writing now a new one. In this case the wl system
+	 * has never seen any PEB used by the original fastmap.
+	 */
+	if (!e) {
+		ubi_assert(ubi->old_fm);
+
+		/* use the ec value from the fastmap */
+		for (i = 0; i < ubi->old_fm->used_blocks; i++) {
+			if (ubi->old_fm->e[i] &&
+				pnum == ubi->old_fm->e[i]->pnum) {
+				e = ubi->old_fm->e[i];
+				ubi->old_fm->e[i] = NULL;
+				break;
+			}
+		}
+		ubi_assert(e);
+		ubi_assert(e->ec);
+		ubi->lookuptbl[pnum] = e;
+	}
+
+	spin_unlock(&ubi->wl_lock);
+
+	err = schedule_erase(ubi, e, torture);
+
+	return err;
+}
+
+/**
  * wear_leveling_worker - wear-leveling worker function.
  * @ubi: UBI device description object
  * @wrk: the work object
@@ -981,6 +1152,8 @@  static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
 
 	dbg_wl("erase PEB %d EC %d", pnum, e->ec);
 
+	ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
+
 	err = sync_erase(ubi, e, wl_wrk->torture);
 	if (!err) {
 		/* Fine, we've erased it successfully */
@@ -1415,6 +1588,7 @@  int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 
 		e->pnum = aeb->pnum;
 		e->ec = aeb->ec;
+		ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
 		ubi->lookuptbl[e->pnum] = e;
 		if (schedule_erase(ubi, e, 0)) {
 			kmem_cache_free(ubi_wl_entry_slab, e);
@@ -1432,7 +1606,10 @@  int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 		e->pnum = aeb->pnum;
 		e->ec = aeb->ec;
 		ubi_assert(e->ec >= 0);
+		ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
+
 		wl_tree_add(e, &ubi->free);
+
 		ubi->lookuptbl[e->pnum] = e;
 	}
 
@@ -1447,6 +1624,9 @@  int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
 			e->pnum = aeb->pnum;
 			e->ec = aeb->ec;
 			ubi->lookuptbl[e->pnum] = e;
+			if (ubi_is_fm_block(ubi, aeb->pnum))
+				continue;
+
 			if (!aeb->scrub) {
 				dbg_wl("add PEB %d EC %d to the used tree",
 				       e->pnum, e->ec);