Commit graph

22 commits

Author SHA1 Message Date
S.Çağlar Onur
fc398769ac UBI: silence warning
drivers/mtd/ubi/vmt.c: In function `ubi_create_volume':
drivers/mtd/ubi/vmt.c:379: warning: statement with no effect

Signed-off-by: S.Çağlar Onur <caglar@pardus.org.tr>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-03-04 11:02:04 +02:00
Artem Bityutskiy
4ccf8cffa9 UBI: add auto-resize feature
The problem: NAND flashes have different amount of initial bad physical
eraseblocks (marked as bad by the manufacturer). For example, for 256MiB
Samsung OneNAND flash there might be from 0 to 40 bad initial eraseblocks,
which is about 2%. When UBI is used as the base system, one needs to know
the exact amount of good physical eraseblocks, because this number is
needed to create the UBI image which is put to the devices during
production. But this number is not know, which forces us to use the
minimum number of good physical eraseblocks. And UBI additionally
reserves some percentage of physical eraseblocks for bad block handling
(default is 1%), so we have 1-3% of PEBs reserved at the end, depending
on the amount of initial bad PEBs. But it is desired to always have
1% (or more, depending on the configuration).

Solution: this patch adds an "auto-resize" flag to the volume table.
The volume which has the "auto-resize" flag will automatically be re-sized
(enlarged) on the first UBI initialization. UBI clears the flag when
the volume is re-sized. Only one volume may have the "auto-resize" flag.

So, the production UBI image may have one volume with "auto-resize"
flag set, and its size is automatically adjusted on the first boot
of the device.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-01-25 16:41:24 +02:00
Artem Bityutskiy
896c0c06aa UBI: use bit-fields
Save 12 bytes of RAM per volume by using bit-fields instead of integers.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-01-25 16:41:24 +02:00
Artem Bityutskiy
4b3cc34061 UBI: bugfix: do not forget to increment vol_count
When creating a new volume, do not forget to increment the
vol_count variable.

Also, users are not interested in internal volumes, so do not show
them in the volumes_count sysfs file.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:18 +02:00
Artem Bityutskiy
e73f4459d9 UBI: add UBI devices reference counting
This is one more step on the way to "removable" UBI devices. It
adds reference counting for UBI devices. Every time a volume on
this device is opened - the device's refcount is increased. It
is also increased if someone is reading any sysfs file of this
UBI device or of one of its volumes.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:17 +02:00
Artem Bityutskiy
40e4d0c166 UBI: tweak volumes locking some more
Make the code more consistent by requiring the caller to lock the
ubi->volume_mutex, because this is what we do for updates.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:16 +02:00
Artem Bityutskiy
d05c77a816 UBI: introduce volume refcounting
Add ref_count field to UBI volumes and remove weired "vol->removed"
field. This way things are better understandable and we do not have
to do whold show_attr operation under spinlock.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:16 +02:00
Artem Bityutskiy
fc75a1e166 UBI: fix error path
Error path in volume creation is bogus. First of, it ovverrides the
'err' variable and returns zero to the caller. Second, ubi_assert()
in the release function is wrong.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:15 +02:00
Artem Bityutskiy
450f872a8e UBI: get device when opening volume
When a volume is opened, get its kref via get_device() call.
And put the reference when closing the volume. With this, we
may have a bit saner volume delete.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:15 +02:00
Artem Bityutskiy
cae0a77125 UBI: tweak volumes locking
Transform vtbl_mutex to volumes_mutex - this just makes code
easier to understand.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:15 +02:00
Artem Bityutskiy
89b96b6929 UBI: improve internal interfaces
Pass volume description object to the EBA function which makes
more sense, and EBA function do not have to find the volume
description object by volume ID.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:15 +02:00
Artem Bityutskiy
01f7b309e4 UBI: improve error messages
Always print error code with error messages, sometimes it is
extremely helpful info.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:14 +02:00
Artem Bityutskiy
49dfc29928 UBI: remove redundant field
Remove redundant ubi->major field - we have it in ubi->cdev.dev
already.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:14 +02:00
Artem Bityutskiy
732aeacff6 UBI: minor tidy-ups
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:14 +02:00
Jesper Juhl
54b2c8f93d UBI: silence a warning
This patch silences the following warning :

  drivers/mtd/ubi/vmt.c:73: warning: 'ret' may be used uninitialized in this function

gcc can't see that we always initialize ret in all situations where it is
actually used. The one case where it's not initialized is when we BUG(),
but gcc doesn't know that we won't then continue and use an uninitialized
'ret'.

This patch results in code that does exactely the same as before, but it
also makes gcc shut up, so we generate one less line of warning noise.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:14 +02:00
Artem Bityutskiy
8bc2296196 UBI: fix sparse warnings
Fix "symbol shadows an earlier one" warnings. Although they are harmless
but it does not hurt to fix them and make sparse happy.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-10-14 13:10:20 +03:00
Vinit Agnihotri
d08c3b78b8 UBI: fix overflow bug
I was experiencing overflows in multiplications for
volume->used_bytes in vmt.c & vtbl.c, while creating & resizing large volumes.

vol->used_bytes is long long however its 2 operands vol->used_ebs &
vol->usable_leb_size
are int. So their multiplication for larger values causes integer overflows.
Typecasting them solves the problem.

My machine & flash details:

64Bit dual-core AMD opteron, 1 GB RAM, linux 2.6.18.3.
mtd size = 6GB, volume size= 5GB, peb_size = 4MB.

heres patch which does the fix.

Signed-off-by: Vinit Agnihotri <vinit.agnihotri@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:58:12 +03:00
Artem Bityutskiy
b89044bfa0 UBI: fix debugging stuff
Do not check volumes which are currently in use because thay may be
in inconsistent state.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:56:05 +03:00
Artem Bityutskiy
94784d9164 UBI: bugfix in error path
When volume creation fails, we have to set ubi->volumes[vol_id]
back to NULL.

This patch also tweaks some debugging stuff.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:55:55 +03:00
Christoph Hellwig
3261ebd7d4 UBI: kill homegrown endian macros
Kill UBI's homegrown endianess handling and replace it with
the standard kernel endianess handling.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:53:49 +03:00
Artem Bityutskiy
16d8cd7ce4 UBI: error path bugfix
No need to unlock the lock, this will be done at out_unlock.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:53:27 +03:00
Artem B. Bityutskiy
801c135ce7 UBI: Unsorted Block Images
UBI (Latin: "where?") manages multiple logical volumes on a single
flash device, specifically supporting NAND flash devices. UBI provides
a flexible partitioning concept which still allows for wear-levelling
across the whole flash device.

In a sense, UBI may be compared to the Logical Volume Manager
(LVM). Whereas LVM maps logical sector numbers to physical HDD sector
numbers, UBI maps logical eraseblocks to physical eraseblocks.

More information may be found at
http://www.linux-mtd.infradead.org/doc/ubi.html

Partitioning/Re-partitioning

  An UBI volume occupies a certain number of erase blocks. This is
  limited by a configured maximum volume size, which could also be
  viewed as the partition size. Each individual UBI volume's size can
  be changed independently of the other UBI volumes, provided that the
  sum of all volume sizes doesn't exceed a certain limit.

  UBI supports dynamic volumes and static volumes. Static volumes are
  read-only and their contents are protected by CRC check sums.

Bad eraseblocks handling

  UBI transparently handles bad eraseblocks. When a physical
  eraseblock becomes bad, it is substituted by a good physical
  eraseblock, and the user does not even notice this.

Scrubbing

  On a NAND flash bit flips can occur on any write operation,
  sometimes also on read. If bit flips persist on the device, at first
  they can still be corrected by ECC, but once they accumulate,
  correction will become impossible. Thus it is best to actively scrub
  the affected eraseblock, by first copying it to a free eraseblock
  and then erasing the original. The UBI layer performs this type of
  scrubbing under the covers, transparently to the UBI volume users.

Erase Counts

  UBI maintains an erase count header per eraseblock. This frees
  higher-level layers (like file systems) from doing this and allows
  for centralized erase count management instead. The erase counts are
  used by the wear-levelling algorithm in the UBI layer. The algorithm
  itself is exchangeable.

Booting from NAND

  For booting directly from NAND flash the hardware must at least be
  capable of fetching and executing a small portion of the NAND
  flash. Some NAND flash controllers have this kind of support. They
  usually limit the window to a few kilobytes in erase block 0. This
  "initial program loader" (IPL) must then contain sufficient logic to
  load and execute the next boot phase.

  Due to bad eraseblocks, which may be randomly scattered over the
  flash device, it is problematic to store the "secondary program
  loader" (SPL) statically. Also, due to bit-flips it may become
  corrupted over time. UBI allows to solve this problem gracefully by
  storing the SPL in a small static UBI volume.

UBI volumes vs. static partitions

  UBI volumes are still very similar to static MTD partitions:

    * both consist of eraseblocks (logical eraseblocks in case of UBI
      volumes, and physical eraseblocks in case of static partitions;
    * both support three basic operations - read, write, erase.

  But UBI volumes have the following advantages over traditional
  static MTD partitions:

    * there are no eraseblock wear-leveling constraints in case of UBI
      volumes, so the user should not care about this;
    * there are no bit-flips and bad eraseblocks in case of UBI volumes.

  So, UBI volumes may be considered as flash devices with relaxed
  restrictions.

Where can it be found?

  Documentation, kernel code and applications can be found in the MTD
  gits.

What are the applications for?

  The applications help to create binary flash images for two purposes: pfi
  files (partial flash images) for in-system update of UBI volumes, and plain
  binary images, with or without OOB data in case of NAND, for a manufacturing
  step. Furthermore some tools are/and will be created that allow flash content
  analysis after a system has crashed..

Who did UBI?

  The original ideas, where UBI is based on, were developed by Andreas
  Arnez, Frank Haverkamp and Thomas Gleixner. Josh W. Boyer and some others
  were involved too. The implementation of the kernel layer was done by Artem
  B. Bityutskiy. The user-space applications and tools were written by Oliver
  Lohmann with contributions from Frank Haverkamp, Andreas Arnez, and Artem.
  Joern Engel contributed a patch which modifies JFFS2 so that it can be run on
  a UBI volume. Thomas Gleixner did modifications to the NAND layer. Alexander
  Schmidt made some testing work as well as core functionality improvements.

Signed-off-by: Artem B. Bityutskiy <dedekind@linutronix.de>
Signed-off-by: Frank Haverkamp <haver@vnet.ibm.com>
2007-04-27 14:23:33 +03:00