[ 53/79] bcache: Journal replay fix

From: Greg Kroah-Hartman
Date: Fri Jul 26 2013 - 17:33:37 EST

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


From: Kent Overstreet <kmo@xxxxxxxxxxxxx>

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

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@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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;
r = m;

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