Fifo structure journal.pin is implemented by a cycle buffer, if the back
index reaches highest location of the cycle buffer, it will be swapped
to 0. Once the swapping happens, it means a smaller fifo index might be
associated to a newer journal entry. So the btree node with oldest
journal entry won't be selected in bch_btree_leaf_dirty() to reference
the dirty B+tree leaf node. This problem may cause bcache journal won't
protect unflushed oldest B+tree dirty leaf node in power failure, and
this B+tree leaf node is possible to beinconsistent after reboot from
power failure.
This patch fixes the fifo index comparing logic in journal_pin_cmp(),
to avoid potential corrupted B+tree leaf node when the back index of
journal pin is swapped.
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
mutex_unlock(&b->write_lock);
}
mutex_unlock(&b->write_lock);
}
+/* return true if journal pin 'l' is newer than 'r' */
+static bool journal_pin_cmp(struct cache_set *c,
+ atomic_t *l,
+ atomic_t *r)
+{
+ int l_idx, r_idx, f_idx, b_idx;
+ bool ret = false;
+
+ l_idx = fifo_idx(&(c)->journal.pin, (l));
+ r_idx = fifo_idx(&(c)->journal.pin, (r));
+ f_idx = (c)->journal.pin.front;
+ b_idx = (c)->journal.pin.back;
+
+ if (l_idx > r_idx)
+ ret = true;
+ /* in case fifo back pointer is swapped */
+ if (b_idx < f_idx) {
+ if (l_idx <= b_idx && r_idx >= f_idx)
+ ret = true;
+ else if (l_idx >= f_idx && r_idx <= b_idx)
+ ret = false;
+ }
+
+ return ret;
+}
+
static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref)
{
struct bset *i = btree_bset_last(b);
static void bch_btree_leaf_dirty(struct btree *b, atomic_t *journal_ref)
{
struct bset *i = btree_bset_last(b);
};
#define BTREE_FLUSH_NR 8
};
#define BTREE_FLUSH_NR 8
-
-#define journal_pin_cmp(c, l, r) \
- (fifo_idx(&(c)->journal.pin, (l)) > fifo_idx(&(c)->journal.pin, (r)))
-
#define JOURNAL_PIN 20000
#define journal_full(j) \
#define JOURNAL_PIN 20000
#define journal_full(j) \