[patch 07/47] md: Dont acknowlege that stripe-expand is complete until it really is.

Greg KH
2008-07-22T23:20:26Z

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2.6.25-stable review patch. If anyone has any objections, please let us
know.

------------------
From: Neil Brown <neilb@notabene.brown>

commit efe311431869b40d67911820a309f9a1a41306f3 upstream

We shouldn't acknowledge that a stripe has been expanded (When
reshaping a raid5 by adding a device) until the moved data has
actually been written out. However we are currently
acknowledging (by calling md_done_sync) when the POST_XOR
is complete and before the write.

So track in s.locked whether there are pending writes, and don't
call md_done_sync yet if there are.

Note: we all set R5_LOCKED on devices which are are about to
read from. This probably isn't technically necessary, but is
usually done when writing a block, and justifies the use of
s.locked here.

This bug can lead to a crash if an array is stopped while an reshape
is in progress.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/raid5.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2861,6 +2861,8 @@ static void handle_stripe5(struct stripe

for (i = conf->raid_disks; i--; ) {
set_bit(R5_Wantwrite, &sh->dev[i].flags);
+ set_bit(R5_LOCKED, &dev->flags);
+ s.locked++;
if (!test_and_set_bit(STRIPE_OP_IO, &sh->ops.pending))
sh->ops.count++;
}
@@ -2874,6 +2876,7 @@ static void handle_stripe5(struct stripe
conf->raid_disks);
s.locked += handle_write_operations5(sh, 1, 1);
} else if (s.expanded &&
+ s.locked == 0 &&
!test_bit(STRIPE_OP_POSTXOR, &sh->ops.pending)) {
clear_bit(STRIPE_EXPAND_READY, &sh->state);
atomic_dec(&conf->reshape_stripes);

--