block: don't autoload drivers on stat

blkdev_get_no_open can trigger the legacy autoload of block drivers.  A
simple stat of a block device has not historically done that, so disable
this behavior again.

Fixes: 9abcfbd ("block: Add atomic write support for statx")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20250423053810.1683309-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

block/bdev.c

@@ -815,13 +815,13 @@ static void blkdev_put_part(struct block_device *part)
 	blkdev_put_whole(whole);
 }
 
-struct block_device *blkdev_get_no_open(dev_t dev)
+struct block_device *blkdev_get_no_open(dev_t dev, bool autoload)
 {
 	struct block_device *bdev;
 	struct inode *inode;
 
 	inode = ilookup(blockdev_superblock, dev);
-	if (!inode && IS_ENABLED(CONFIG_BLOCK_LEGACY_AUTOLOAD)) {
+	if (!inode && autoload && IS_ENABLED(CONFIG_BLOCK_LEGACY_AUTOLOAD)) {
 		blk_request_module(dev);
 		inode = ilookup(blockdev_superblock, dev);
 		if (inode)
@@ -1043,7 +1043,7 @@ struct file *bdev_file_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
 	if (ret)
 		return ERR_PTR(ret);
 
-	bdev = blkdev_get_no_open(dev);
+	bdev = blkdev_get_no_open(dev, true);
 	if (!bdev)
 		return ERR_PTR(-ENXIO);
 
@@ -1321,7 +1321,7 @@ void bdev_statx(struct path *path, struct kstat *stat,
 	 * use I_BDEV() here; the block device has to be looked up by i_rdev
 	 * instead.
 	 */
-	bdev = blkdev_get_no_open(d_backing_inode(path->dentry)->i_rdev);
+	bdev = blkdev_get_no_open(d_backing_inode(path->dentry)->i_rdev, false);
 	if (!bdev)
 		return;
 

block/blk-cgroup.c

@@ -797,7 +797,7 @@ int blkg_conf_open_bdev(struct blkg_conf_ctx *ctx)
 		return -EINVAL;
 	input = skip_spaces(input);
 
-	bdev = blkdev_get_no_open(MKDEV(major, minor));
+	bdev = blkdev_get_no_open(MKDEV(major, minor), true);
 	if (!bdev)
 		return -ENODEV;
 	if (bdev_is_partition(bdev)) {

block/blk.h

@@ -94,7 +94,7 @@ static inline void blk_wait_io(struct completion *done)
 		wait_for_completion_io(done);
 }
 
-struct block_device *blkdev_get_no_open(dev_t dev);
+struct block_device *blkdev_get_no_open(dev_t dev, bool autoload);
 void blkdev_put_no_open(struct block_device *bdev);
 
 #define BIO_INLINE_VECS 4

block/fops.c

@@ -642,7 +642,7 @@ static int blkdev_open(struct inode *inode, struct file *filp)
 	if (ret)
 		return ret;
 
-	bdev = blkdev_get_no_open(inode->i_rdev);
+	bdev = blkdev_get_no_open(inode->i_rdev, true);
 	if (!bdev)
 		return -ENXIO;