bcache: Fix for when no journal entries are found

The journal replay code didn't handle this case, causing it to go into
an infinite loop...

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c
index c0017ca32b7662afec1de6a9640d7b0b012275fc..f5203dfc4cfe95d3c27d5935ac1455d8fc7bc53c 100644 (file)
--- a/drivers/md/bcache/journal.c
+++ b/drivers/md/bcache/journal.c
@@ -153,7 +153,8 @@ int bch_journal_read(struct cache_set *c, struct list_head *list,
                bitmap_zero(bitmap, SB_JOURNAL_BUCKETS);
                pr_debug("%u journal buckets", ca->sb.njournal_buckets);
 
-               /* Read journal buckets ordered by golden ratio hash to quickly
+               /*
+                * Read journal buckets ordered by golden ratio hash to quickly
                 * find a sequence of buckets with valid journal entries
                 */
                for (i = 0; i < ca->sb.njournal_buckets; i++) {
@@ -166,18 +167,20 @@ int bch_journal_read(struct cache_set *c, struct list_head *list,
                                goto bsearch;
                }
 
-               /* If that fails, check all the buckets we haven't checked
+               /*
+                * If that fails, check all the buckets we haven't checked
                 * already
                 */
                pr_debug("falling back to linear search");
 
-               for (l = 0; l < ca->sb.njournal_buckets; l++) {
-                       if (test_bit(l, bitmap))
-                               continue;
-
+               for (l = find_first_zero_bit(bitmap, ca->sb.njournal_buckets);
+                    l < ca->sb.njournal_buckets;
+                    l = find_next_zero_bit(bitmap, ca->sb.njournal_buckets, l + 1))
                        if (read_bucket(l))
                                goto bsearch;
-               }
+
+               if (list_empty(list))
+                       continue;
 bsearch:
                /* Binary search */
                m = r = find_next_bit(bitmap, ca->sb.njournal_buckets, l + 1);
@@ -197,10 +200,12 @@ bsearch:
                                r = m;
                }
 
-               /* Read buckets in reverse order until we stop finding more
+               /*
+                * Read buckets in reverse order until we stop finding more
                 * journal entries
                 */
-               pr_debug("finishing up");
+               pr_debug("finishing up: m %u njournal_buckets %u",
+                        m, ca->sb.njournal_buckets);
                l = m;
 
                while (1) {
@@ -228,9 +233,10 @@ bsearch:
                        }
        }
 
-       c->journal.seq = list_entry(list->prev,
-                                   struct journal_replay,
-                                   list)->j.seq;
+       if (!list_empty(list))
+               c->journal.seq = list_entry(list->prev,
+                                           struct journal_replay,
+                                           list)->j.seq;
 
        return 0;
 #undef read_bucket