linux-kernel - [ 53/79] bcache: Journal replay fix

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Date:	Fri, 26 Jul 2013 13:47:43 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Kent Overstreet <kmo@...erainc.com>
Subject: [ 53/79] bcache: Journal replay fix

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kent Overstreet <kmo@...erainc.com>

commit faa5673617656ee58369a3cfe4a312cfcdc59c81 upstream.

The journal replay code starts by finding something that looks like a
valid journal entry, then it does a binary search over the unchecked
region of the journal for the journal entries with the highest sequence
numbers.

Trouble is, the logic was wrong - journal_read_bucket() returns true if
it found journal entries we need, but if the range of journal entries
we're looking for loops around the end of the journal - in that case
journal_read_bucket() could return true when it hadn't found the highest
sequence number we'd seen yet, and in that case the binary search did
the wrong thing. Whoops.

Signed-off-by: Kent Overstreet <kmo@...erainc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/bcache/journal.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -182,9 +182,14 @@ bsearch:
 		pr_debug("starting binary search, l %u r %u", l, r);

 		while (l + 1 < r) {
+			seq = list_entry(list->prev, struct journal_replay,
+					 list)->j.seq;
+
 			m = (l + r) >> 1;
+			read_bucket(m);

-			if (read_bucket(m))
+			if (seq != list_entry(list->prev, struct journal_replay,
+					      list)->j.seq)
 				l = m;
 			else
 				r = m;

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