Patch "md/raid10: fix two problems with RAID10 resync." has been added to the 3.10-stable tree

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This is a note to let you know that I've just added the patch titled

    md/raid10: fix two problems with RAID10 resync.

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     md-raid10-fix-two-problems-with-raid10-resync.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 7bb23c4934059c64cbee2e41d5d24ce122285176 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb@xxxxxxx>
Date: Tue, 16 Jul 2013 16:50:47 +1000
Subject: md/raid10: fix two problems with RAID10 resync.

From: NeilBrown <neilb@xxxxxxx>

commit 7bb23c4934059c64cbee2e41d5d24ce122285176 upstream.

1/ When an different between blocks is found, data is copied from
   one bio to the other.  However bv_len is used as the length to
   copy and this could be zero.  So use r10_bio->sectors to calculate
   length instead.
   Using bv_len was probably always a bit dubious, but the introduction
   of bio_advance made it much more likely to be a problem.

2/ When preparing some blocks for sync, we don't set BIO_UPTODATE
   except on bios that we schedule for a read.  This ensures that
   missing/failed devices don't confuse the loop at the top of
   sync_request write.
   Commit 8be185f2c9d54d6 "raid10: Use bio_reset()"
   removed a loop which set BIO_UPTDATE on all appropriate bios.
   So we need to re-add that flag.

These bugs were introduced in 3.10, so this patch is suitable for
3.10-stable, and can remove a potential for data corruption.

Reported-by: Brassow Jonathan <jbrassow@xxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/md/raid10.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -2075,11 +2075,17 @@ static void sync_request_write(struct md
 			 * both 'first' and 'i', so we just compare them.
 			 * All vec entries are PAGE_SIZE;
 			 */
-			for (j = 0; j < vcnt; j++)
+			int sectors = r10_bio->sectors;
+			for (j = 0; j < vcnt; j++) {
+				int len = PAGE_SIZE;
+				if (sectors < (len / 512))
+					len = sectors * 512;
 				if (memcmp(page_address(fbio->bi_io_vec[j].bv_page),
 					   page_address(tbio->bi_io_vec[j].bv_page),
-					   fbio->bi_io_vec[j].bv_len))
+					   len))
 					break;
+				sectors -= len/512;
+			}
 			if (j == vcnt)
 				continue;
 			atomic64_add(r10_bio->sectors, &mddev->resync_mismatches);
@@ -3385,6 +3391,7 @@ static sector_t sync_request(struct mdde
 
 		if (bio->bi_end_io == end_sync_read) {
 			md_sync_acct(bio->bi_bdev, nr_sectors);
+			set_bit(BIO_UPTODATE, &bio->bi_flags);
 			generic_make_request(bio);
 		}
 	}


Patches currently in stable-queue which might be from neilb@xxxxxxx are

queue-3.10/md-raid10-fix-two-problems-with-raid10-resync.patch
queue-3.10/md-raid10-fix-two-bugs-affecting-raid10-reshape.patch
queue-3.10/md-raid10-fix-bug-which-causes-all-raid10-reshapes-to-move-no-data.patch
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