1 files changed, 51 insertions, 16 deletions

diff --git a/block/bdev.c b/block/bdev.c
index 6a34179192c9..889ec6e002d7 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -152,27 +152,65 @@ static void set_init_blocksize(struct block_device *bdev)
 				    get_order(bsize));
 }
 
-int set_blocksize(struct file *file, int size)
+/**
+ * bdev_validate_blocksize - check that this block size is acceptable
+ * @bdev:	blockdevice to check
+ * @block_size:	block size to check
+ *
+ * For block device users that do not use buffer heads or the block device
+ * page cache, make sure that this block size can be used with the device.
+ *
+ * Return: On success zero is returned, negative error code on failure.
+ */
+int bdev_validate_blocksize(struct block_device *bdev, int block_size)
 {
-	struct inode *inode = file->f_mapping->host;
-	struct block_device *bdev = I_BDEV(inode);
-
-	if (blk_validate_block_size(size))
+	if (blk_validate_block_size(block_size))
 		return -EINVAL;
 
 	/* Size cannot be smaller than the size supported by the device */
-	if (size < bdev_logical_block_size(bdev))
+	if (block_size < bdev_logical_block_size(bdev))
 		return -EINVAL;
 
+	return 0;
+}
+EXPORT_SYMBOL_GPL(bdev_validate_blocksize);
+
+int set_blocksize(struct file *file, int size)
+{
+	struct inode *inode = file->f_mapping->host;
+	struct block_device *bdev = I_BDEV(inode);
+	int ret;
+
+	ret = bdev_validate_blocksize(bdev, size);
+	if (ret)
+		return ret;
+
 	if (!file->private_data)
 		return -EINVAL;
 
 	/* Don't change the size if it is same as current */
 	if (inode->i_blkbits != blksize_bits(size)) {
+		/*
+		 * Flush and truncate the pagecache before we reconfigure the
+		 * mapping geometry because folio sizes are variable now.  If a
+		 * reader has already allocated a folio whose size is smaller
+		 * than the new min_order but invokes readahead after the new
+		 * min_order becomes visible, readahead will think there are
+		 * "zero" blocks per folio and crash.  Take the inode and
+		 * invalidation locks to avoid racing with
+		 * read/write/fallocate.
+		 */
+		inode_lock(inode);
+		filemap_invalidate_lock(inode->i_mapping);
+
 		sync_blockdev(bdev);
+		kill_bdev(bdev);
+
 		inode->i_blkbits = blksize_bits(size);
 		mapping_set_folio_min_order(inode->i_mapping, get_order(size));
 		kill_bdev(bdev);
+		filemap_invalidate_unlock(inode->i_mapping);
+		inode_unlock(inode);
 	}
 	return 0;
 }
@@ -777,13 +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)
@@ -1005,7 +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);
 
@@ -1274,18 +1312,15 @@ void sync_bdevs(bool wait)
  */
 void bdev_statx(const struct path *path, struct kstat *stat, u32 request_mask)
 {
-	struct inode *backing_inode;
 	struct block_device *bdev;
 
-	backing_inode = d_backing_inode(path->dentry);
-
 	/*
-	 * Note that backing_inode is the inode of a block device node file,
-	 * not the block device's internal inode.  Therefore it is *not* valid
-	 * to use I_BDEV() here; the block device has to be looked up by i_rdev
+	 * Note that d_backing_inode() returns the block device node inode, not
+	 * the block device's internal inode.  Therefore it is *not* valid to
+	 * use I_BDEV() here; the block device has to be looked up by i_rdev
 	 * instead.
 	 */
-	bdev = blkdev_get_no_open(backing_inode->i_rdev);
+	bdev = blkdev_get_no_open(d_backing_inode(path->dentry)->i_rdev, false);
 	if (!bdev)
 		return;