Hi Brian,
From: Brian Norris [mailto:computersforpeace@gmail.com]
On Fri, Dec 13, 2013 at 02:42:57PM +0530, Pekon Gupta wrote: This patch updates starting offset for free bytes in OOB which can be used by file-systems to store their metadata (like clean-marker in case of JFFS2).
This should be describing a regression fix, right? We don't just arbitrarily change the "OOB free" layout; we need a reason. So please describe it here.
(It seems like an off-by-one, or off-by-<N> error, where the oobfree region was miscalculated.)
Possibly you can paste an example intended ecclayout as well as an incorrect layout that was calculated before this fix.
Signed-off-by: Pekon Gupta pekon@ti.com
drivers/mtd/nand/omap2.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-)
diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
[...]
- /* populate remaining ECC layout data */
- ecclayout->oobfree->length = mtd->oobsize - (BADBLOCK_MARKER_LENGTH +
ecclayout->eccbytes);@@ -1990,6 +1977,10 @@ static int omap_nand_probe(struct platform_device *pdev) err = -EINVAL; goto return_error; }
- /* populate remaining ECC layout data */
- ecclayout->oobfree->offset = ecclayout->eccpos[ecclayout->eccbytes] + 1;
Hmm, this line seems a little odd. The ecclayout->eccpos[] array and the value of ecclayout->eccbytes sould be related as follows:
let N = ecclayout->eccbytes
This means the eccpos[] array should have N entries, indexed 0 to N-1, and eccpos[N] is out of bounds. But you are accessing eccpos[N] above (i.e., eccpos[ecclayout->eccbytes]). Are you sure this is correct? It seems like it should be:
ecclayout->oobfree->offset = ecclayout->eccpos[ecclayout->eccbytes - 1] + 1;
Thanks for this catch. Yes, you are correct. It's a typo. This wasn't caught as I had tested everything on UBIFS which does not use 'oobfree'. Also, as ecclayout->eccpos is defined as large static array, so this dint caused problems either. #define MTD_MAX_ECCPOS_ENTRIES_LARGE 640 struct nand_ecclayout { __u32 eccpos[MTD_MAX_ECCPOS_ENTRIES_LARGE];
But, I think mtd_tests.nand_oobtest would have caught this. I'll include this change in next version.
<stripping down the CC list to avoid getting moderated by u-boot mailman>
with regards, pekon