On 4/19/19 6:05 PM, Coly Li wrote:
Current journal_max_cmp() and journal_min_cmp() assume that smaller fifo index indicating elder journal entries, but this is only true when fifo index is not swapped.
Fifo structure journal.pin is implemented by a cycle buffer, if the head 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 by btree_flush_write() to flush out to cache device. The result is, the oldest journal entries may always has no chance to be written into cache device, and after a reboot bch_journal_replay() may complain some journal entries are missing.
This patch handles the fifo index swapping conditions properly, then in btree_flush_write() the btree node with oldest journal entry can be slected from c->flush_btree correctly.
Cc: stable@vger.kernel.org Signed-off-by: Coly Li colyli@suse.de
drivers/md/bcache/journal.c | 47 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 41 insertions(+), 6 deletions(-)
diff --git a/drivers/md/bcache/journal.c b/drivers/md/bcache/journal.c index bdb6f9cefe48..bc0e01151155 100644 --- a/drivers/md/bcache/journal.c +++ b/drivers/md/bcache/journal.c @@ -464,12 +464,47 @@ int bch_journal_replay(struct cache_set *s, struct list_head *list) } /* Journalling */ -#define journal_max_cmp(l, r) \
- (fifo_idx(&c->journal.pin, btree_current_write(l)->journal) < \
fifo_idx(&(c)->journal.pin, btree_current_write(r)->journal))-#define journal_min_cmp(l, r) \
- (fifo_idx(&c->journal.pin, btree_current_write(l)->journal) > \
fifo_idx(&(c)->journal.pin, btree_current_write(r)->journal))+#define journal_max_cmp(l, r) \ +({ \
- int l_idx, r_idx, f_idx, b_idx; \
- bool _ret = true; \
\- l_idx = fifo_idx(&c->journal.pin, btree_current_write(l)->journal); \
- r_idx = fifo_idx(&c->journal.pin, btree_current_write(r)->journal); \
- f_idx = c->journal.pin.front; \
- b_idx = c->journal.pin.back; \
\- _ret = (l_idx < r_idx); \
- /* in case fifo back pointer is swapped */ \
- if (b_idx < f_idx) { \
if (l_idx <= b_idx && r_idx >= f_idx) \_ret = false; \else if (l_idx >= f_idx && r_idx <= b_idx) \_ret = true; \- } \
- _ret; \
+})
+#define journal_min_cmp(l, r) \ +({ \
- int l_idx, r_idx, f_idx, b_idx; \
- bool _ret = true; \
\- l_idx = fifo_idx(&c->journal.pin, btree_current_write(l)->journal); \
- r_idx = fifo_idx(&c->journal.pin, btree_current_write(r)->journal); \
- f_idx = c->journal.pin.front; \
- b_idx = c->journal.pin.back; \
\- _ret = (l_idx > r_idx); \
- /* 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; \- } \
- _ret; \
+}) static void btree_flush_write(struct cache_set *c) {
Please make it a proper function. This is far too convoluted for being handled via #define, and it would avoid cluttering the function namespace with hidden variables.
Cheers,
Hannes