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path: root/drivers/mtd/ubi/kapi.c
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2008-01-25UBI: fix warningsArtem Bityutskiy
drivers/mtd/ubi/cdev.c: In function ‘vol_cdev_read’: drivers/mtd/ubi/cdev.c:187: warning: unused variable ‘vol_id’ CC [M] drivers/mtd/ubi/kapi.o drivers/mtd/ubi/kapi.c: In function ‘ubi_leb_erase’: drivers/mtd/ubi/kapi.c:483: warning: unused variable ‘vol_id’ drivers/mtd/ubi/kapi.c: In function ‘ubi_leb_unmap’: drivers/mtd/ubi/kapi.c:544: warning: unused variable ‘vol_id’ drivers/mtd/ubi/kapi.c: In function ‘ubi_leb_map’: drivers/mtd/ubi/kapi.c:582: warning: unused variable ‘vol_id’ Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26UBI: use separate mutex for volumes checkingArtem Bityutskiy
Introduce a separate mutex which serializes volumes checking, because we cammot really use volumes_mutex - it cases reverse locking problems with mtd_tbl_mutex when gluebi is used - thanks to lockdep. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26UBI: add UBI devices reference countingArtem Bityutskiy
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>
2007-12-26UBI: introduce volume refcountingArtem Bityutskiy
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>
2007-12-26UBI: fix and cleanup volume opening functionsArtem Bityutskiy
This patch fixes error codes of the functions - if the device number is out of range, -EINVAL should be returned. It also removes unneeded try_module_get call from the open by name function. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26UBI: get device when opening volumeArtem Bityutskiy
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>
2007-12-26UBI: tweak volumes lockingArtem Bityutskiy
Transform vtbl_mutex to volumes_mutex - this just makes code easier to understand. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-12-26UBI: improve internal interfacesArtem Bityutskiy
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>
2007-12-26UBI: remove redundant fieldArtem Bityutskiy
Remove redundant ubi->major field - we have it in ubi->cdev.dev already. 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>
2007-10-14UBI: don't use array index before testing if it is negativeJesper Juhl
I can't find anything guaranteeing that 'ubi_num' cannot be <0 in drivers/mtd/ubi/kapi.c::ubi_open_volume(), and in fact the code even tests for that and errors out if so. Unfortunately the test for "ubi_num < 0" happens after we've already used 'ubi_num' as an array index - bad thing to do if it is negative. This patch moves the test earlier in the function and then moves the indexing using that variable after the check. A bit safer :-) Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18UBI: remove unneeded error checksArtem Bityutskiy
Pointed to by viro. Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18UBI: cleanup usage of try_module_getFernando Luis Vázquez Cao
The use of try_module_get(THIS_MODULE) in ubi_get_device_info does not offer real protection against unexpected driver unloads, since we could be preempted before try_modules_get gets executed. It is the caller who should manipulate the refcounts. Besides, ubi_get_device_info is an exported symbol which guarantees protection when accessed through symbol_get. Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
2007-07-18UBI: do not let to read too muchArtem Bityutskiy
In case of static volumes it is prohibited to read more data then available. 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>