To easily track filesystem from a pmem device, we introduce a holder for
dax_device structure, and also its operation. This holder is used to
remember who is using this dax_device:
- When it is the backend of a filesystem, the holder will be the
superblock of this filesystem.
- When this pmem device is one of the targets in a mapped device, the
holder will be this mapped device. In this case, the mapped device
has its own dax_device and it will follow the first rule. So that we
can finally track to the filesystem we needed.
The holder and holder_ops will be set when filesystem is being mounted,
or an target device is being activated.
Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
---
drivers/dax/super.c | 63 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/dax.h | 25 ++++++++++++++++++
2 files changed, 88 insertions(+)
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index f7701e943019..ed1b27198382 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -23,7 +23,10 @@
* @cdev: optional character interface for "device dax"
* @host: optional name for lookups where the device path is not available
* @private: dax driver private data
+ * @holder_data: holder of a dax_device: could be filesystem or mapped device
* @flags: state and boolean properties
+ * @ops: operations for dax_device
+ * @holder_ops: operations for the inner holder
*/
struct dax_device {
struct hlist_node list;
@@ -32,8 +35,10 @@ struct dax_device {
const char *host;
void *private;
struct percpu_rw_semaphore rwsem;
+ void *holder_data;
unsigned long flags;
const struct dax_operations *ops;
+ const struct dax_holder_operations *holder_ops;
};
static dev_t dax_devt;
@@ -376,6 +381,29 @@ int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
}
EXPORT_SYMBOL_GPL(dax_zero_page_range);
+int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off,
+ u64 len, int mf_flags)
+{
+ int rc;
+
+ dax_read_lock(dax_dev);
+ if (!dax_alive(dax_dev)) {
+ rc = -ENXIO;
+ goto out;
+ }
+
+ if (!dax_dev->holder_ops) {
+ rc = -EOPNOTSUPP;
+ goto out;
+ }
+
+ rc = dax_dev->holder_ops->notify_failure(dax_dev, off, len, mf_flags);
+out:
+ dax_read_unlock(dax_dev);
+ return rc;
+}
+EXPORT_SYMBOL_GPL(dax_holder_notify_failure);
+
#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)
@@ -438,6 +466,10 @@ void kill_dax(struct dax_device *dax_dev)
return;
dax_write_lock(dax_dev);
clear_bit(DAXDEV_ALIVE, &dax_dev->flags);
+
+ /* clear holder data */
+ dax_dev->holder_ops = NULL;
+ dax_dev->holder_data = NULL;
dax_write_unlock(dax_dev);
spin_lock(&dax_host_lock);
@@ -622,6 +654,37 @@ void put_dax(struct dax_device *dax_dev)
}
EXPORT_SYMBOL_GPL(put_dax);
+void dax_set_holder(struct dax_device *dax_dev, void *holder,
+ const struct dax_holder_operations *ops)
+{
+ dax_write_lock(dax_dev);
+ if (!dax_alive(dax_dev)) {
+ dax_write_unlock(dax_dev);
+ return;
+ }
+
+ dax_dev->holder_data = holder;
+ dax_dev->holder_ops = ops;
+ dax_write_unlock(dax_dev);
+}
+EXPORT_SYMBOL_GPL(dax_set_holder);
+
+void *dax_get_holder(struct dax_device *dax_dev)
+{
+ void *holder;
+
+ dax_read_lock(dax_dev);
+ if (!dax_alive(dax_dev)) {
+ dax_read_unlock(dax_dev);
+ return NULL;
+ }
+
+ holder = dax_dev->holder_data;
+ dax_read_unlock(dax_dev);
+ return holder;
+}
+EXPORT_SYMBOL_GPL(dax_get_holder);
+
/**
* inode_dax: convert a public inode into its dax_dev
* @inode: An inode with i_cdev pointing to a dax_dev
diff --git a/include/linux/dax.h b/include/linux/dax.h
index e38711d6c519..891c3e8a40e6 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -38,9 +38,24 @@ struct dax_operations {
int (*zero_page_range)(struct dax_device *, pgoff_t, size_t);
};
+struct dax_holder_operations {
+ /*
+ * notify_failure - notify memory failure into inner holder device
+ * @dax_dev: the dax device which contains the holder
+ * @offset: offset on this dax device where memory failure occurs
+ * @len: length of this memory failure event
+ * @flags: action flags for memory failure handler
+ */
+ int (*notify_failure)(struct dax_device *dax_dev, u64 offset,
+ u64 len, int mf_flags);
+};
+
extern struct attribute_group dax_attribute_group;
#if IS_ENABLED(CONFIG_DAX)
+void dax_set_holder(struct dax_device *dax_dev, void *holder,
+ const struct dax_holder_operations *ops);
+void *dax_get_holder(struct dax_device *dax_dev);
struct dax_device *alloc_dax(void *private, const char *host,
const struct dax_operations *ops, unsigned long flags);
void put_dax(struct dax_device *dax_dev);
@@ -70,6 +85,14 @@ static inline bool daxdev_mapping_supported(struct vm_area_struct *vma,
return dax_synchronous(dax_dev);
}
#else
+static inline void dax_set_holder(struct dax_device *dax_dev, void *holder,
+ const struct dax_holder_operations *ops)
+{
+}
+static inline void *dax_get_holder(struct dax_device *dax_dev)
+{
+ return NULL;
+}
static inline struct dax_device *alloc_dax(void *private, const char *host,
const struct dax_operations *ops, unsigned long flags)
{
@@ -198,6 +221,8 @@ size_t dax_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff, void *addr,
size_t bytes, struct iov_iter *i);
int dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
size_t nr_pages);
+int dax_holder_notify_failure(struct dax_device *dax_dev, u64 off, u64 len,
+ int mf_flags);
void dax_flush(struct dax_device *dax_dev, void *addr, size_t size);
ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
--
2.33.0
