UBI: add a comment

It is not clear why we schedule PEB for scrubbing in case of
-EBADMSG. Elaborate.

Requested-by: Kyungmin Park <kmpark@infradead.org>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
index 3c4d68f2cfd4..42a7815086b7 100644
--- a/drivers/mtd/ubi/vtbl.c
+++ b/drivers/mtd/ubi/vtbl.c
@@ -385,7 +385,16 @@ static struct ubi_vtbl_record *process_lvol(struct ubi_device *ubi,
                 err = ubi_io_read_data(ubi, leb[seb->lnum], seb->pnum, 0,
                                        ubi->vtbl_size);
                 if (err == UBI_IO_BITFLIPS || err == -EBADMSG)
-                        /* Scrub the PEB later */
+                        /*
+                         * Scrub the PEB later. Note, -EBADMSG indicates an
+                         * uncorrectable ECC error, but we have our own CRC and
+                         * the data will be checked later. If the data is OK,
+                         * the PEB will be scrubbed (because we set
+                         * seb->scrub). If the data is not OK, the contents of
+                         * the PEB will be recovered from the second copy, and
+                         * seb->scrub will be cleared in
+                         * 'ubi_scan_add_used()'.
+                         */
                         seb->scrub = 1;
                 else if (err)
                         goto out_free;