md: always set MD_RECOVERY_INTR when interrupting a reshape thread.

commit 2ac295a544dcae9299cba13ce250419117ae7fd1 upstream.

Commit 8313b8e57f55b15e5b7f7fc5d1630bbf686a9a97
   md: fix problem when adding device to read-only array with bitmap.

added a called to md_reap_sync_thread() which cause a reshape thread
to be interrupted (in particular, it could cause md_thread() to never even
call md_do_sync()).
However it didn't set MD_RECOVERY_INTR so ->finish_reshape() would not
know that the reshape didn't complete.

This only happens when mddev->ro is set and normally reshape threads
don't run in that situation.  But raid5 and raid10 can start a reshape
thread during "run" is the array is in the middle of a reshape.
They do this even if ->ro is set.

So it is best to set MD_RECOVERY_INTR before abortingg the
sync thread, just in case.

Though it rare for this to trigger a problem it can cause data corruption
because the reshape isn't finished properly.
So it is suitable for any stable which the offending commit was applied to.
(3.2 or later)

Fixes: 8313b8e57f55b15e5b7f7fc5d1630bbf686a9a97
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index a12a63c..8b013f8 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7840,6 +7840,7 @@ void md_check_recovery(struct mddev *mddev)
                        /* There is no thread, but we need to call
                         * ->spare_active and clear saved_raid_disk
                         */
+                       set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                        md_reap_sync_thread(mddev);
                        clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
                        goto unlock;