diff options
Diffstat (limited to 'drivers/dax')
| -rw-r--r-- | drivers/dax/super.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/dax/super.c b/drivers/dax/super.c index d7714d8afb0f..efa5f6186019 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -232,6 +232,7 @@ EXPORT_SYMBOL_GPL(dax_recovery_write); int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off, u64 len, int mf_flags) { + const struct dax_holder_operations *ops; int rc, id; id = dax_read_lock(); @@ -240,12 +241,19 @@ int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off, goto out; } - if (!dax_dev->holder_ops) { + /* + * Read holder_ops once: a concurrent fs_put_dax() can clear it without + * synchronizing against readers. Without the single fetch the compiler + * could reload between the NULL check and the call and dereference a + * NULL ops. + */ + ops = READ_ONCE(dax_dev->holder_ops); + if (!ops) { rc = -EOPNOTSUPP; goto out; } - rc = dax_dev->holder_ops->notify_failure(dax_dev, off, len, mf_flags); + rc = ops->notify_failure(dax_dev, off, len, mf_flags); out: dax_read_unlock(id); return rc; |