[PATCH 07/14] raw: don't keep unopened block device around

Christoph Hellwig
2020-09-21T07:20:07Z

Turn binding into a normal dev_t as the struct block device doesn't
buy us anything and use blkdev_open_by_dev to actually open it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/char/raw.c | 51 +++++++++++++++++-----------------------------
1 file changed, 19 insertions(+), 32 deletions(-)

diff --git a/drivers/char/raw.c b/drivers/char/raw.c
index ccf5bd528642da..5d52a1f4738c76 100644
--- a/drivers/char/raw.c
+++ b/drivers/char/raw.c
@@ -28,7 +28,8 @@
#include <linux/uaccess.h>

struct raw_device_data {
- struct block_device *binding;
+ dev_t binding;
+ struct block_device *bdev;
int inuse;
};

@@ -73,14 +74,15 @@ static int raw_open(struct inode *inode, struct file *filp)
/*
* All we need to do on open is check that the device is bound.
*/
- bdev = raw_devices[minor].binding;
err = -ENODEV;
- if (!bdev)
+ if (!raw_devices[minor].binding)
goto out;
- bdgrab(bdev);
- err = blkdev_get(bdev, filp->f_mode | FMODE_EXCL, raw_open);
- if (err)
+ bdev = blkdev_get_by_dev(raw_devices[minor].binding,
+ filp->f_mode | FMODE_EXCL, raw_open);
+ if (IS_ERR(bdev)) {
+ err = PTR_ERR(bdev);
goto out;
+ }
err = set_blocksize(bdev, bdev_logical_block_size(bdev));
if (err)
goto out1;
@@ -90,6 +92,7 @@ static int raw_open(struct inode *inode, struct file *filp)
file_inode(filp)->i_mapping =
bdev->bd_inode->i_mapping;
filp->private_data = bdev;
+ raw_devices[minor].bdev = bdev;
mutex_unlock(&raw_mutex);
return 0;

@@ -110,7 +113,7 @@ static int raw_release(struct inode *inode, struct file *filp)
struct block_device *bdev;

mutex_lock(&raw_mutex);
- bdev = raw_devices[minor].binding;
+ bdev = raw_devices[minor].bdev;
if (--raw_devices[minor].inuse == 0)
/* Here inode->i_mapping == bdev->bd_inode->i_mapping */
inode->i_mapping = &inode->i_data;
@@ -133,6 +136,7 @@ raw_ioctl(struct file *filp, unsigned int command, unsigned long arg)
static int bind_set(int number, u64 major, u64 minor)
{
dev_t dev = MKDEV(major, minor);
+ dev_t raw = MKDEV(RAW_MAJOR, number);
struct raw_device_data *rawdev;
int err = 0;

@@ -166,25 +170,17 @@ static int bind_set(int number, u64 major, u64 minor)
mutex_unlock(&raw_mutex);
return -EBUSY;
}
- if (rawdev->binding) {
- bdput(rawdev->binding);
+ if (rawdev->binding)
module_put(THIS_MODULE);
- }
+
+ rawdev->binding = dev;
if (!dev) {
/* unbind */
- rawdev->binding = NULL;
- device_destroy(raw_class, MKDEV(RAW_MAJOR, number));
+ device_destroy(raw_class, raw);
} else {
- rawdev->binding = bdget(dev);
- if (rawdev->binding == NULL) {
- err = -ENOMEM;
- } else {
- dev_t raw = MKDEV(RAW_MAJOR, number);
- __module_get(THIS_MODULE);
- device_destroy(raw_class, raw);
- device_create(raw_class, NULL, raw, NULL,
- "raw%d", number);
- }
+ __module_get(THIS_MODULE);
+ device_destroy(raw_class, raw);
+ device_create(raw_class, NULL, raw, NULL, "raw%d", number);
}
mutex_unlock(&raw_mutex);
return err;
@@ -192,18 +188,9 @@ static int bind_set(int number, u64 major, u64 minor)

static int bind_get(int number, dev_t *dev)
{
- struct raw_device_data *rawdev;
- struct block_device *bdev;
-
if (number <= 0 || number >= max_raw_minors)
return -EINVAL;
-
- rawdev = &raw_devices[number];
-
- mutex_lock(&raw_mutex);
- bdev = rawdev->binding;
- *dev = bdev ? bdev->bd_dev : 0;
- mutex_unlock(&raw_mutex);
+ *dev = raw_devices[number].binding;
return 0;
}

--
2.28.0