Commit Graph

17 Commits

Author SHA1 Message Date
Artem Bityutskiy
ebaaf1af3e UBI: fix kernel-doc errors and warnings
No functional changes, just tweak comments to make kernel-doc
work fine and stop complaining.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-07-24 13:36:09 +03:00
Artem Bityutskiy
9c9ec14770 UBI: fix checkpatch.pl errors and warnings
Just out or curiousity ran checkpatch.pl for whole UBI,
and discovered there are quite a few of stylistic issues.
Fix them.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-07-24 13:36:09 +03:00
Artem Bityutskiy
8c1e6ee10b UBI: rework scrubbing messages
If bit-flips happen often, UBI prints to many messages. Lessen
the amount by only printing the messages when the PEB has been
scrubbed. Also, print torturing messages.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-07-24 13:34:46 +03:00
Artem Bityutskiy
c8566350a3 UBI: fix and re-work debugging stuff
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-07-24 13:34:45 +03:00
Artem Bityutskiy
85c6e6e282 UBI: amend commentaries
Hch asked not to use "unit" for sub-systems, let it be so.
Also some other commentaries modifications.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-07-24 13:32:56 +03:00
Artem Bityutskiy
a4f0fcdfb2 UBI: be verbose when debuggin is enabled
Make I/O function to be always verbose when about CRC errors
and magic number errors when I/O debugging is enabled.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-04-17 11:31:58 +03:00
Artem Bityutskiy
2362a53ec5 UBI: fix error code in ubi_io_read()
When NAND detects an ECC error, it returns -EBADMSG. It does not
stop reading requested data if one page has an ECC error, it keeps
going and reads all the requested data. If it fails to read all
the data, it does not return -EBADMSG, but returns the error code
which reflects the reason of the failure.

But some drivers may have bugs (e.g., OneNAND had) and stop reading
after the first ECC error, so it returns -EBADMSG. In turn, UBI
propagates this up to the caller. The caller will treat this as
"all the requested data was read, but there was an ECC error".

So we change the error code to -EIO if it is -EBADMSG and the read
length is less then the requested length. We also add an assertion,
so if UBI debugging is enabled, UBI will bug.

Pointed-to-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26 19:15:13 +02:00
Artem Bityutskiy
6986646ba7 UBI: use byte hexdump
More handy since word hexdump prints in host endian.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-10-14 13:10:21 +03:00
Artem Bityutskiy
e88d6e10e5 UBI: do not use vmalloc on I/O path
Similar reason as in case of the previous patch: it causes
deadlocks if a filesystem with writeback support works on top
of UBI. So pre-allocate needed buffers when attaching MTD device.
We also need mutexes to protect the buffers, but they do not
cause much contantion because they are used in recovery, torture,
and WL copy routines, which are called seldom.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-10-14 13:10:21 +03:00
Artem Bityutskiy
33818bbb84 UBI: allocate memory with GFP_NOFS
Use GFP_NOFS flag when allocating memory on I/O path, because otherwise
we may deadlock the filesystem which works on top of us. We observed
the deadlocks with UBIFS. Example:

VFS->FS lock a lock->UBI->kmalloc()->VFS writeback->FS locks the same
lock again.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-10-14 13:10:20 +03:00
Artem Bityutskiy
ef6075fbfc UBI: use linux print_hex_dump(), not home-grown one
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-10-14 13:10:20 +03:00
Artem Bityutskiy
8d2d4011f1 UBI: add more prints
I hit those situations and found out lack of print messages. Add more prints
when erase problems occur.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-10-14 13:10:20 +03:00
Artem Bityutskiy
63b6c1ed56 UBI: fix comments
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:59:01 +03:00
Brijesh Singh
2f176f7987 UBI: fix signed-unsigned multiplication
There is signed multiplication assigned to unsigned ei.addr in io.c.
This causes wrong addresses for big multiplication.This patch solves the
problem.

Signed-off-by: Brijesh Singh <brijesh.s.singh@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:57:34 +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
92ad8f3750 UBI: use vmalloc for large buffers
UBI allocates temporary buffers of PEB size, which may be 256KiB.
Use vmalloc instead of kmalloc for such big temporary buffers.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18 16:53:08 +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