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path: root/include/linux/mtd/ubi.h
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2012-05-21UBI: modify ubi_wl_flush function to clear work queue for a lnumJoel Reardon
This patch modifies ubi_wl_flush to force the erasure of particular volume id / logical eraseblock number pairs. Previous functionality is preserved when passing UBI_ALL for both values. The locations where ubi_wl_flush were called are appropriately changed: ubi_leb_erase only flushes for the erased LEB, and ubi_create_volume forces only flushing for its volume id. External code can call this new feature via the new function ubi_flush() added to kapi.c, which simply passes through to ubi_wl_flush(). This was tested by disabling the call to do_work in ubi thread, which results in the work queue remaining unless explicitly called to remove. UBIFS was changed to call ubifs_leb_change 50 times for four different LEBs. Then the new function was called to clear the queue: passing wrong volume ids / lnum, correct ones, and finally UBI_ALL for both to ensure it was finally all cleard. The work queue was dumped each time and the selective removal of the particular LEB numbers was observed. Extra checks were enabled and ubifs's integck was also run. Finally, the drive was repeatedly filled and emptied to ensure that the queue was cleared normally. Artem: amended the patch. Signed-off-by: Joel Reardon <reardonj@inf.ethz.ch> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
2012-05-21UBI: introduce UBI_ALL constantArtem Bityutskiy
Joel will use it in his 'ubi_flush()' extention to specify all eraseblocks. Also amend the comment for UBI_UNKNOWN - it is used beyond attaching info structure now. Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
2012-05-20UBI: Kill data type hintRichard Weinberger
We do not need this feature and to our shame it even was not working and there was a bug found very recently. -- Artem Bityutskiy Without the data type hint UBI2 (fastmap) will be easier to implement. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
2011-06-23UBI: clarify the volume notification types' docDavid Wagner
I realized the new descriptions of ADDED and REMOVED could also be misleading: they can also be triggered after using a userland util (ubi{mk,rm}vol). Artem: amend the commentaries Signed-off-by David Wagner <david.wagner@free-electrons.com> Signed-off-by: Artem Bityutskiy <dedekind1@gmail.com>
2011-04-14UBI: fix minor stylistic issuesArtem Bityutskiy
Fix checkpatch.pl errors and warnings: * space before tab * line over 80 characters * include linux/ioctl.h instead of asm/ioctl.h Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2011-03-08UBI: provide LEB offset informationArtem Bityutskiy
Provide the LEB offset information in the UBI device information data structure. This piece of information is required by UBIFS to find out what are the LEB offsets which are aligned to the max. write size. If LEB offset not aligned to max. write size, then UBIFS has to take this into account to write more optimally. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2011-03-08UBI: incorporate maximum write sizeArtem Bityutskiy
Incorporate MTD write buffer size into UBI device information because UBIFS needs this field. UBI does not use it ATM, just provides to upper layers in 'struct ubi_device_info'. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2009-11-24UBI: Add ubi_open_volume_pathCorentin Chary
Add an 'ubi_open_volume_path(path, mode)' function which works like 'open_bdev_exclusive(path, mode, ...)' where path is the special file representing the UBI volume, typically /dev/ubi0_0. This is needed to teach UBIFS being able to mount UBI character devices. [Comments and the patch were amended a bit by Artem] Signed-off-by: Corentin Chary <corentincj@iksaif.net> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2009-06-02UBI: add notification APIDmitry Pervushin
UBI volume notifications are intended to create the API to get clients notified about volume creation/deletion, renaming and re-sizing. A client can subscribe to these notifications using 'ubi_volume_register()' and cancel the subscription using 'ubi_volume_unregister()'. When UBI volumes change, a blocking notifier is called. Clients also can request "added" events on all volumes that existed before client subscribed to the notifications. If we use notifications instead of calling functions like 'ubi_gluebi_xxx()', we can make the MTD emulation layer to be more flexible: build it as a separate module and load/unload it on demand. [Artem: many cleanups, rework locking, add "updated" event, provide device/volume info in notifiers] Signed-off-by: Dmitry Pervushin <dpervushin@embeddedalley.com> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-07-24UBI: amend commentariesArtem Bityutskiy
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>
2008-07-24UBI: add ubi_sync() interfaceArtem Bityutskiy
To flush MTD device caches. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2008-01-25UBI: introduce atomic LEB change ioctlArtem Bityutskiy
We have to be able to change individual LEBs for utilities like ubifsck, ubifstune. For example, ubifsck has to be able to fix errors on the media, ubifstune has to be able to change the the superblock, hence this ioctl. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26UBI: add ubi_leb_map interfaceArtem Bityutskiy
The idea of this interface belongs to Adrian Hunter. The interface is extremely useful when one has to have a guarantee that an LEB will contain all 0xFFs even in case of an unclean reboot. UBI does have an 'ubi_leb_erase()' call which may do this, but it is stupid and ineffecient, because it flushes whole queue. I should be re-worked to just be a pair of unmap, map calls. The user of the interfaci is UBIFS at the moment. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-04-27UBI: Unsorted Block ImagesArtem B. Bityutskiy
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>