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authorMikulas Patocka <mpatocka@redhat.com>2017-08-31 21:47:43 -0400
committerMike Snitzer <snitzer@redhat.com>2017-09-11 11:00:55 -0400
commitc3ca015fab6df124c933b91902f3f2a3473f9da5 (patch)
treea43633630e05a08bbb14de927b4d399b5d2f6c1d /drivers/dax
parentb5e8ad92c3ac0b073bbf08ffd1a6a31d3449caae (diff)
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dax: remove the pmem_dax_ops->flush abstraction
Commit abebfbe2f731 ("dm: add ->flush() dax operation support") is buggy. A DM device may be composed of multiple underlying devices and all of them need to be flushed. That commit just routes the flush request to the first device and ignores the other devices. It could be fixed by adding more complex logic to the device mapper. But there is only one implementation of the method pmem_dax_ops->flush - that is pmem_dax_flush() - and it calls arch_wb_cache_pmem(). Consequently, we don't need the pmem_dax_ops->flush abstraction at all, we can call arch_wb_cache_pmem() directly from dax_flush() because dax_dev->ops->flush can't ever reach anything different from arch_wb_cache_pmem(). It should be also pointed out that for some uses of persistent memory it is needed to flush only a very small amount of data (such as 1 cacheline), and it would be overkill if we go through that device mapper machinery for a single flushed cache line. Fix this by removing the pmem_dax_ops->flush abstraction and call arch_wb_cache_pmem() directly from dax_flush(). Also, remove the device mapper code that forwards the flushes. Fixes: abebfbe2f731 ("dm: add ->flush() dax operation support") Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/dax')
-rw-r--r--drivers/dax/super.c21
1 files changed, 14 insertions, 7 deletions
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 938eb4868f7f..8b458f1b30c7 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -189,8 +189,10 @@ static umode_t dax_visible(struct kobject *kobj, struct attribute *a, int n)
if (!dax_dev)
return 0;
- if (a == &dev_attr_write_cache.attr && !dax_dev->ops->flush)
+#ifndef CONFIG_ARCH_HAS_PMEM_API
+ if (a == &dev_attr_write_cache.attr)
return 0;
+#endif
return a->mode;
}
@@ -255,18 +257,23 @@ size_t dax_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
}
EXPORT_SYMBOL_GPL(dax_copy_from_iter);
-void dax_flush(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
- size_t size)
+#ifdef CONFIG_ARCH_HAS_PMEM_API
+void arch_wb_cache_pmem(void *addr, size_t size);
+void dax_flush(struct dax_device *dax_dev, void *addr, size_t size)
{
- if (!dax_alive(dax_dev))
+ if (unlikely(!dax_alive(dax_dev)))
return;
- if (!test_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags))
+ if (unlikely(!test_bit(DAXDEV_WRITE_CACHE, &dax_dev->flags)))
return;
- if (dax_dev->ops->flush)
- dax_dev->ops->flush(dax_dev, pgoff, addr, size);
+ arch_wb_cache_pmem(addr, size);
}
+#else
+void dax_flush(struct dax_device *dax_dev, void *addr, size_t size)
+{
+}
+#endif
EXPORT_SYMBOL_GPL(dax_flush);
void dax_write_cache(struct dax_device *dax_dev, bool wc)