linux/drivers/mtd/ubi/eba.c, branch v2.6.39-rc2

UBI: preserve corrupted PEBs

2010-10-19T14:19:57Z

Currently UBI erases all corrupted eraseblocks, irrespectively of the nature of corruption: corruption due to power cuts and non-power cut corruption. The former case is OK, but the latter is not, because UBI may destroy potentially important data. With this patch, during scanning, when UBI hits a PEB with corrupted VID header, it checks whether this PEB contains only 0xFF data. If yes, it is safe to erase this PEB and it is put to the 'erase' list. If not, this may be important data and it is better to avoid erasing this PEB. Instead, UBI puts it to the corr list and moves out of the pool of available PEB. IOW, UBI preserves this PEB. Such corrupted PEB lessen the amount of available PEBs. So the more of them we accumulate, the less PEBs are available. The maximum amount of non-power cut corrupted PEBs is 8. This patch is a response to UBIFS problem where reporter (Matthew L. Creech ) observes that UBIFS index points to an unmapped LEB. The theory is that corresponding PEB somehow got corrupted and UBI wiped it. This patch (actually a series of patches) tries to make sure such PEBs are preserved - this would make it is easier to analyze the corruption. Signed-off-by: Artem Bityutskiy

UBI: rename IO error code

2010-10-19T14:19:56Z

Rename UBI_IO_BAD_HDR_READ into UBI_IO_BAD_HDR_EBADMSG which is presumably more self-documenting and readable. Indeed, the '_READ' suffix does not tell much and even confuses, while '_EBADMSG' tells about uncorrectable ECC error, because we use -EBADMSG all over the place to represent ECC errors. Signed-off-by: Artem Bityutskiy

UBI: do not warn unnecessarily

2010-08-02T04:21:19Z

Currently, when UBI attaches an MTD device and cannot reserve all 1% (by default) of PEBs for bad eraseblocks handling, it prints a warning. However, Matthew L. Creech is not very happy to see this warning, because he did reserve enough of PEB at the beginning, but with time some PEBs became bad. The warning is not necessary in this case. This patch makes UBI print the warning o if this is a new image o of this is used image and the amount of reserved PEBs is only 10% (or less) of the size of the reserved PEB pool. Signed-off-by: Artem Bityutskiy

UBI: introduce a new IO return code

2010-06-04T08:30:42Z

This patch introduces the %UBI_IO_BAD_HDR_READ return code for the I/O level function. We will use this code in order to distinguish between "corrupted header possibly because this is non-ubi data" and "corrupted header possibly because of real data corruption and ECC error". So far this patch does not introduce any functional change, just a preparation. This patch is pased on a patch from Sebastian Andrzej Siewior Signed-off-by: Artem Bityutskiy Reviewed-by: Sebastian Andrzej Siewior Tested-by: Sebastian Andrzej Siewior

UBI: simplify IO error codes

2010-06-04T08:30:42Z

We do not really need 2 separate error codes for indicating bad VID and bad EC headers (UBI_IO_BAD_EC_HDR, UBI_IO_BAD_VID_HDR), it is enough to have only one UBI_IO_BAD_HDR return code. This patch does not introduce any functional change, only some code simplification. Signed-off-by: Artem Bityutskiy Reviewed-by: Sebastian Andrzej Siewior Tested-by: Sebastian Andrzej Siewior

trivial: fix typo "to to" in multiple files

2009-09-21T13:14:55Z

Signed-off-by: Anand Gadiyar Signed-off-by: Jiri Kosina

UBI: fix double free on error path

2009-07-24T17:08:52Z

If we fail in 'ubi_eba_init_scan()', we free 'ubi->volumes[i]->eba_tbl' in there, but also later free it in 'free_internal_volumes()'. Fix this by assigning NULL to 'ubi->volumes[i]->eba_tbl' after it is freed. Signed-off-by: Adrian Hunter Signed-off-by: Artem Bityutskiy

UBI: handle more error codes

2009-06-10T13:13:28Z

The UBIFS WL worker may encounter read errors and there is logic which makes a decision whether we should do one of: 1. cancel the operation and move the PEB with the read errors to the 'erroneous' list; 2. switch to R/O mode. ATM, only -EIO errors trigger 1., other errors trigger 2. The idea is that if we know we encountered an I/O error, do 1. Otherwise, we do not know how to react, and do 2., just in case. E.g., if the underlying driver became crazy because of a bug, we do not want to harm any data, and switch to R/O mode. This patch does 2 things: 1. Makes sure reads from the source PEB always cause 1. This is more consistent with other reads which come from the upper layers and never cause R/O. 2. Teaches UBI to do 1. also on -EBADMSG, UBI_IO_BAD_VID_HDR, -ENOMEM, and -ETIMEOUT. But this is only when reading the target PEB. This preblems were hunted by Adrian Hunter. Signed-off-by: Artem Bityutskiy

UBI: fix multiple spelling typos

2009-06-10T13:13:27Z

Some of the typos were indicated by Adrian Hunter, some by 'aspell'. Signed-off-by: Artem Bityutskiy

UBI: do not switch to R/O mode on read errors

2009-06-02T10:53:35Z

This patch improves UBI errors handling. ATM UBI switches to R/O mode when the WL worker fails to read the source PEB. This means that the upper layers (e.g., UBIFS) has no chances to unmap the erroneous PEB and fix the error. This patch changes this behaviour and makes UBI put PEBs like this into a separate RB-tree, thus preventing the WL worker from hitting the same read errors again and again. But there is a 10% limit on a maximum amount of PEBs like this. If there are too much of them, UBI switches to R/O mode. Additionally, this patch teaches UBI not to panic and switch to R/O mode if after a PEB has been copied, the target LEB cannot be read back. Instead, now UBI cancels the operation and schedules the target PEB for torturing. The error paths has been tested by ingecting errors into 'ubi_eba_copy_leb()'. Signed-off-by: Artem Bityutskiy