bdev: remove bdev pointer from struct bdev_handle

We can always go directly via:

* I_BDEV(bdev_file->f_inode)
* I_BDEV(bdev_file->f_mapping->host)

So keeping struct bdev in struct bdev_handle is redundant.

Link: https://lore.kernel.org/r/20240123-vfs-bdev-file-v2-30-adbd023e19cc@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

Author: brauner

block/bdev.c

@@ -51,8 +51,7 @@ EXPORT_SYMBOL(I_BDEV);
 
 struct block_device *file_bdev(struct file *bdev_file)
 {
-	struct bdev_handle *handle = bdev_file->private_data;
-	return handle->bdev;
+	return I_BDEV(bdev_file->f_mapping->host);
 }
 EXPORT_SYMBOL(file_bdev);
 
@@ -891,15 +890,14 @@ int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
 
 	if (unblock_events)
 		disk_unblock_events(disk);
-	handle->bdev = bdev;
 	handle->holder = holder;
 	handle->mode = mode;
 
 	bdev_file->f_flags |= O_LARGEFILE;
 	bdev_file->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT;
 	if (bdev_nowait(bdev))
 		bdev_file->f_mode |= FMODE_NOWAIT;
-	bdev_file->f_mapping = handle->bdev->bd_inode->i_mapping;
+	bdev_file->f_mapping = bdev->bd_inode->i_mapping;
 	bdev_file->f_wb_err = filemap_sample_wb_err(bdev_file->f_mapping);
 	bdev_file->private_data = handle;
 
@@ -985,30 +983,30 @@ struct file *bdev_file_open_by_path(const char *path, blk_mode_t mode,
 				    void *holder,
 				    const struct blk_holder_ops *hops)
 {
-	struct file *bdev_file;
+	struct file *file;
 	dev_t dev;
 	int error;
 
 	error = lookup_bdev(path, &dev);
 	if (error)
 		return ERR_PTR(error);
 
-	bdev_file = bdev_file_open_by_dev(dev, mode, holder, hops);
-	if (!IS_ERR(bdev_file) && (mode & BLK_OPEN_WRITE)) {
-		struct bdev_handle *handle = bdev_file->private_data;
-		if (bdev_read_only(handle->bdev)) {
-			fput(bdev_file);
-			bdev_file = ERR_PTR(-EACCES);
+	file = bdev_file_open_by_dev(dev, mode, holder, hops);
+	if (!IS_ERR(file) && (mode & BLK_OPEN_WRITE)) {
+		if (bdev_read_only(file_bdev(file))) {
+			fput(file);
+			file = ERR_PTR(-EACCES);
 		}
 	}
 
-	return bdev_file;
+	return file;
 }
 EXPORT_SYMBOL(bdev_file_open_by_path);
 
-void bdev_release(struct bdev_handle *handle)
+void bdev_release(struct file *bdev_file)
 {
-	struct block_device *bdev = handle->bdev;
+	struct block_device *bdev = file_bdev(bdev_file);
+	struct bdev_handle *handle = bdev_file->private_data;
 	struct gendisk *disk = bdev->bd_disk;
 
 	/*

block/blk.h

@@ -26,7 +26,6 @@ struct blk_flush_queue {
 };
 
 struct bdev_handle {
-	struct block_device *bdev;
 	void *holder;
 	blk_mode_t mode;
 };
@@ -522,7 +521,7 @@ static inline int req_ref_read(struct request *req)
 	return atomic_read(&req->ref);
 }
 
-void bdev_release(struct bdev_handle *handle);
+void bdev_release(struct file *bdev_file);
 int bdev_open(struct block_device *bdev, blk_mode_t mode, void *holder,
 	      const struct blk_holder_ops *hops, struct file *bdev_file);
 int bdev_permission(dev_t dev, blk_mode_t mode, void *holder);

block/fops.c

@@ -623,7 +623,7 @@ static int blkdev_open(struct inode *inode, struct file *filp)
 static int blkdev_release(struct inode *inode, struct file *filp)
 {
 	if (filp->private_data)
-		bdev_release(filp->private_data);
+		bdev_release(filp);
 	return 0;
 }