md/raid5-cache: disable reshape completely

We don't support reshape yet if an array supports log device. Previously we
determine the fact by checking ->log. However, ->log could be NULL after a log
device is removed, but the array is still marked to support log device. Don't
allow reshape in this case too. User can disable log device support by setting
'consistency_policy' to 'resync' then do reshape.

Reported-by: Xiao Ni <xni@redhat.com>
Tested-by: Xiao Ni <xni@redhat.com>
Signed-off-by: Shaohua Li <shli@fb.com>

drivers/md/raid5-log.h

@@ -46,6 +46,11 @@ extern int ppl_modify_log(struct r5conf *conf, struct md_rdev *rdev, bool add);
 extern void ppl_quiesce(struct r5conf *conf, int quiesce);
 extern int ppl_handle_flush_request(struct r5l_log *log, struct bio *bio);
 
+static inline bool raid5_has_log(struct r5conf *conf)
+{
+	return test_bit(MD_HAS_JOURNAL, &conf->mddev->flags);
+}
+
 static inline bool raid5_has_ppl(struct r5conf *conf)
 {
 	return test_bit(MD_HAS_PPL, &conf->mddev->flags);

drivers/md/raid5.c

@@ -733,7 +733,7 @@ static bool stripe_can_batch(struct stripe_head *sh)
 {
 	struct r5conf *conf = sh->raid_conf;
 
-	if (conf->log || raid5_has_ppl(conf))
+	if (raid5_has_log(conf) || raid5_has_ppl(conf))
 		return false;
 	return test_bit(STRIPE_BATCH_READY, &sh->state) &&
 		!test_bit(STRIPE_BITMAP_PENDING, &sh->state) &&
@@ -7737,7 +7737,7 @@ static int raid5_resize(struct mddev *mddev, sector_t sectors)
 	sector_t newsize;
 	struct r5conf *conf = mddev->private;
 
-	if (conf->log || raid5_has_ppl(conf))
+	if (raid5_has_log(conf) || raid5_has_ppl(conf))
 		return -EINVAL;
 	sectors &= ~((sector_t)conf->chunk_sectors - 1);
 	newsize = raid5_size(mddev, sectors, mddev->raid_disks);
@@ -7788,7 +7788,7 @@ static int check_reshape(struct mddev *mddev)
 {
 	struct r5conf *conf = mddev->private;
 
-	if (conf->log || raid5_has_ppl(conf))
+	if (raid5_has_log(conf) || raid5_has_ppl(conf))
 		return -EINVAL;
 	if (mddev->delta_disks == 0 &&
 	    mddev->new_layout == mddev->layout &&