There are a number of accesses to __rcu variables that should be safe
because nr_pending in the disk is known to be elevated.
Create a wrapper around rcu_dereference_protected() to annotate these
accesses and verify that nr_pending is non-zero.
This fixes a number of sparse warnings.
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
drivers/md/raid5.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4815f5351818..0f29a2769cb3 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2648,6 +2648,16 @@ static void shrink_stripes(struct r5conf *conf)
conf->slab_cache = NULL;
}
+/*
+ * This helper wraps rcu_dereference_protected() and can be used when
+ * it is known that the nr_pending of the rdev is elevated.
+ */
+static struct md_rdev *rdev_pend_deref(struct md_rdev __rcu *rdev)
+{
+ return rcu_dereference_protected(rdev,
+ atomic_read(&rcu_access_pointer(rdev)->nr_pending));
+}
+
static void raid5_end_read_request(struct bio * bi)
{
struct stripe_head *sh = bi->bi_private;
@@ -2674,9 +2684,9 @@ static void raid5_end_read_request(struct bio * bi)
* In that case it moved down to 'rdev'.
* rdev is not removed until all requests are finished.
*/
- rdev = conf->disks[i].replacement;
+ rdev = rdev_pend_deref(conf->disks[i].replacement);
if (!rdev)
- rdev = conf->disks[i].rdev;
+ rdev = rdev_pend_deref(conf->disks[i].rdev);
if (use_new_offset(conf, sh))
s = sh->sector + rdev->new_data_offset;
@@ -2790,11 +2800,11 @@ static void raid5_end_write_request(struct bio *bi)
for (i = 0 ; i < disks; i++) {
if (bi == &sh->dev[i].req) {
- rdev = conf->disks[i].rdev;
+ rdev = rdev_pend_deref(conf->disks[i].rdev);
break;
}
if (bi == &sh->dev[i].rreq) {
- rdev = conf->disks[i].replacement;
+ rdev = rdev_pend_deref(conf->disks[i].replacement);
if (rdev)
replacement = 1;
else
@@ -2802,7 +2812,7 @@ static void raid5_end_write_request(struct bio *bi)
* replaced it. rdev is not removed
* until all requests are finished.
*/
- rdev = conf->disks[i].rdev;
+ rdev = rdev_pend_deref(conf->disks[i].rdev);
break;
}
}
@@ -5213,23 +5223,23 @@ static void handle_stripe(struct stripe_head *sh)
struct r5dev *dev = &sh->dev[i];
if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
/* We own a safe reference to the rdev */
- rdev = conf->disks[i].rdev;
+ rdev = rdev_pend_deref(conf->disks[i].rdev);
if (!rdev_set_badblocks(rdev, sh->sector,
RAID5_STRIPE_SECTORS(conf), 0))
md_error(conf->mddev, rdev);
rdev_dec_pending(rdev, conf->mddev);
}
if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
- rdev = conf->disks[i].rdev;
+ rdev = rdev_pend_deref(conf->disks[i].rdev);
rdev_clear_badblocks(rdev, sh->sector,
RAID5_STRIPE_SECTORS(conf), 0);
rdev_dec_pending(rdev, conf->mddev);
}
if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
- rdev = conf->disks[i].replacement;
+ rdev = rdev_pend_deref(conf->disks[i].replacement);
if (!rdev)
/* rdev have been moved down */
- rdev = conf->disks[i].rdev;
+ rdev = rdev_pend_deref(conf->disks[i].rdev);
rdev_clear_badblocks(rdev, sh->sector,
RAID5_STRIPE_SECTORS(conf), 0);
rdev_dec_pending(rdev, conf->mddev);
--
2.30.2
