kernel.git/drivers/mtd/ubi/wl.c, branch linux-2.6.37.y

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: handle bit-flips when no header found

2010-10-19T14:19:56Z

Currently UBI has one small flaw - when we read EC or VID header, but find only 0xFF bytes, we return UBI_IO_FF and do not report whether we had bit-flips or not. In case of the VID header, the scanning code adds this PEB to the free list, even though there were bit-flips. Imagine the following situation: we start writing VID header to a PEB and have a power cut, so the PEB becomes unstable. When we scan and read the PEB, we get a bit-flip. Currently, UBI would just ignore this and treat the PEB as free. This patch changes UBI behavior and now UBI will schedule this PEB for erasure. Signed-off-by: Artem Bityutskiy

UBI: remove duplicate IO error codes

2010-10-19T14:19:56Z

The 'UBI_IO_PEB_EMPTY' and 'UBI_IO_PEB_FREE' are essentially the same and mean that there are only 0xFF bytes instead of headers. Simplify UBI a little by turning them into a single 'UBI_IO_FF' error code. Also, stop maintaining commentaries in 'ubi_io_read_vid_hdr()' which are almost identical to commentaries in 'ubi_io_read_ec_hdr()'. Signed-off-by: Artem Bityutskiy

UBI: do not oops when erroneous PEB is scheduled for scrubbing

2010-08-30T10:32:31Z

When an erroneous PEB is scheduling for scrubbing, we end up with the following oops: [] (prot_queue_del+0x0/0x50) from [] (ubi_wl_scrub_peb+0xec/0x13c) [] (ubi_wl_scrub_peb+0x0/0x13c) from [] (ubi_eba_read_leb+0x200/0x428) [] (ubi_eba_read_leb+0x0/0x428) from [] (ubi_leb_read+0xe8/0x138) [] (ubi_leb_read+0x0/0x138) from [] (ubifs_start_scan+0x7c/0xf4) [] (ubifs_start_scan+0x0/0xf4) from [] (ubifs_recover_leb+0x3c/0x730) [] (ubifs_recover_leb+0x0/0x730) from [] (ubifs_recover_log_leb+0xc8/0x2dc) [] (ubifs_recover_log_leb+0x0/0x2dc) from [] (ubifs_replay_journal+0xb90/0x13a4) [] (ubifs_replay_journal+0x0/0x13a4) from [] (ubifs_fill_super+0xb84/0x1054) [] (ubifs_fill_super+0x0/0x1054) from [] (ubifs_get_sb+0xc4/0x2ac) [] (ubifs_get_sb+0x0/0x2ac) from [] (vfs_kern_mount+0x58/0x94) [] (vfs_kern_mount+0x0/0x94) from [] (do_kern_mount+0x40/0xe8) [] (do_kern_mount+0x0/0xe8) from [] (do_new_mount+0x68/0x8c) [] (do_new_mount+0x0/0x8c) from [] (do_mount+0x15c/0x1b8) [] (do_mount+0x0/0x1b8) from [] (sys_mount+0x8c/0xd4) [] (sys_mount+0x0/0xd4) from [] (ret_fast_syscall+0x0/0x2c) Kernel panic - not syncing: Fatal exception The problem is that 'ubi_wl_scrub_peb()' does not expect that PEBs may be in the erroneous tree, which is a bug. This patch fixes the bug and adds corresponding check to 'ubi_wl_scrub_peb()'. Now it will simply ignore erroneous PEBs, instead of causing an oops. Reported-by: Matthieu CASTET Signed-off-by: Artem Bityutskiy

UBI: fix s/then/than/ typos

2010-05-07T05:33:10Z

Signed-off-by: Shinya Kuribayashi Signed-off-by: Artem Bityutskiy

UBI: simplify debugging return codes

2010-02-01T13:16:37Z

UBI debugging functions were a little bit over-engineered and returned more error codes than needed, and the callers had to do useless checks. Simplify the return codes. Impact: only debugging code is affected, which means that for non-developers this is a no-op patch. Signed-off-by: Artem Bityutskiy

UBI: remove bogus debugging checks

2009-07-05T15:47:05Z

The 'paranoid_check_empty()' is bogus because, which is easilly seen on NOR flash, which has long erase cycles, and which may easilly end-up with half-erased eraseblocks. In this case the paranoid check fails. I is just wrong to assume that PEBs which do not have EC headers always contain all 0xFF. Such assumption should not be made on the I/O level, which is quite low. Thus, just kill the check. Signed-off-by: Artem Bityutskiy

UBI: add empty eraseblocks verification

2009-07-05T15:47:03Z

This patch adds code which makes sure eraseblocks contain all 0xFF bytes before starting using them. The verification is done only when debugging checks are enabled. 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: fix kmem_cache_free on error patch

2009-06-10T13:13:27Z

'kmem_cache_free()' oopeses if NULL is passed, and there is one error-path place where UBI may call it with NULL object. This problem was pointed to by Adrian Hunter. Signed-off-by: Artem Bityutskiy