From: John Groves <[email protected]>
If the file is a fsdev_dax open, take the dax_dev from the device inode's
i_cdev. Return with a reference grabbed on the private dax inode.
Make dax_dev_get() static again (internal to super.c for alloc_dax), export
fsdev_dax_from_file() instead.
This fix is in response to a Sashiko review, and some subsequent analysis.
About the 'fixes' tag: this removes the export of dax_dev_get(), which was
flawed, and replaces it with fsdev_dax_from_file(). It feels like the fixes
tag makes sense for correcting an ABI error.
Fixes: 2ae624d5a555d ("dax: export dax_dev_get()")
Originally-by: John Groves <[email protected]>
Signed-off-by: Miklos Szeredi <[email protected]>
---
drivers/dax/fsdev.c | 23 +++++++++++++++++++++++
drivers/dax/super.c | 3 +--
include/linux/dax.h | 3 ++-
3 files changed, 26 insertions(+), 3 deletions(-)
diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c
index 598604bf5ac5..910665c1f492 100644
--- a/drivers/dax/fsdev.c
+++ b/drivers/dax/fsdev.c
@@ -234,6 +234,29 @@ static const struct file_operations fsdev_fops = {
.release = fsdev_release,
};
+/**
+ * fsdev_dax_from_file - get dax_device from an open file
+ * @file: open device file
+ *
+ * Returns a dax_device pointer if @file refers to a fsdev_dax device.
+ * Otherwise return NULL.
+ *
+ * Caller must put_dax() the returned device when done.
+ */
+struct dax_device *fsdev_dax_from_file(struct file *file)
+{
+ struct dax_device *dax_dev;
+
+ if (file->f_op != &fsdev_fops)
+ return NULL;
+
+ dax_dev = inode_dax(file_inode(file));
+ ihold(dax_inode(dax_dev));
+
+ return dax_dev;
+}
+EXPORT_SYMBOL_GPL(fsdev_dax_from_file);
+
/*
* Acquire the dev_pagemap for probe: the static (pre-populated) one if
* present, or a devm-allocated one for the dynamic case. Note that
diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index 45f84b0eb909..25836f389bde 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -565,7 +565,7 @@ static int dax_set(struct inode *inode, void *data)
return 0;
}
-struct dax_device *dax_dev_get(dev_t devt)
+static struct dax_device *dax_dev_get(dev_t devt)
{
struct dax_device *dax_dev;
struct inode *inode;
@@ -588,7 +588,6 @@ struct dax_device *dax_dev_get(dev_t devt)
return dax_dev;
}
-EXPORT_SYMBOL_GPL(dax_dev_get);
struct dax_device *alloc_dax(void *private, const struct dax_operations *ops)
{
diff --git a/include/linux/dax.h b/include/linux/dax.h
index fe6c3ded1b50..2c9fc81f031b 100644
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -54,7 +54,6 @@ struct dax_device *alloc_dax(void *private, const struct
dax_operations *ops);
void *dax_holder(struct dax_device *dax_dev);
void put_dax(struct dax_device *dax_dev);
void kill_dax(struct dax_device *dax_dev);
-struct dax_device *dax_dev_get(dev_t devt);
void dax_write_cache(struct dax_device *dax_dev, bool wc);
bool dax_write_cache_enabled(struct dax_device *dax_dev);
bool dax_synchronous(struct dax_device *dax_dev);
@@ -323,3 +322,5 @@ typedef int (*walk_hmem_fn)(struct device *dev, int
target_nid,
const struct resource *res);
int walk_hmem_resources(struct device *dev, walk_hmem_fn fn);
#endif
+
+struct dax_device *fsdev_dax_from_file(struct file *file);
--
2.54.0
