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authorArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2010-09-03 16:08:15 -0400
committerArtem Bityutskiy <Artem.Bityutskiy@nokia.com>2010-10-19 10:19:57 -0400
commit5fc01ab6934c43b42c41bc753fe1123c16d7f38f (patch)
tree174a1e1a0d283ec8ca4c756d7f354a475ac46a36 /drivers/mtd/ubi/eba.c
parentfeeba4b872e5166ca64c44fbb5bbec234dfce199 (diff)
UBI: preserve corrupted PEBs
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 <mlcreech@gmail.com>) 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 <Artem.Bityutskiy@nokia.com>
Diffstat (limited to 'drivers/mtd/ubi/eba.c')
-rw-r--r--drivers/mtd/ubi/eba.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 334865ef5220..4be671815014 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -1201,6 +1201,9 @@ static void print_rsvd_warning(struct ubi_device *ubi,
1201 1201
1202 ubi_warn("cannot reserve enough PEBs for bad PEB handling, reserved %d," 1202 ubi_warn("cannot reserve enough PEBs for bad PEB handling, reserved %d,"
1203 " need %d", ubi->beb_rsvd_pebs, ubi->beb_rsvd_level); 1203 " need %d", ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
1204 if (ubi->corr_peb_count)
1205 ubi_warn("%d PEBs are corrupted and not used",
1206 ubi->corr_peb_count);
1204} 1207}
1205 1208
1206/** 1209/**
@@ -1263,6 +1266,9 @@ int ubi_eba_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si)
1263 if (ubi->avail_pebs < EBA_RESERVED_PEBS) { 1266 if (ubi->avail_pebs < EBA_RESERVED_PEBS) {
1264 ubi_err("no enough physical eraseblocks (%d, need %d)", 1267 ubi_err("no enough physical eraseblocks (%d, need %d)",
1265 ubi->avail_pebs, EBA_RESERVED_PEBS); 1268 ubi->avail_pebs, EBA_RESERVED_PEBS);
1269 if (ubi->corr_peb_count)
1270 ubi_err("%d PEBs are corrupted and not used",
1271 ubi->corr_peb_count);
1266 err = -ENOSPC; 1272 err = -ENOSPC;
1267 goto out_free; 1273 goto out_free;
1268 } 1274 }