From 26e06f5b13671d194d67ae8e2b66f524ab174153 Mon Sep 17 00:00:00 2001 From: Luis Chamberlain Date: Wed, 3 Nov 2021 16:04:34 -0700 Subject: block: update __register_blkdev() probe documentation __register_blkdev() is used to register a probe callback, and that callback is typically used to call add_disk(). Now that we are able to capture errors for add_disk(), we need to fix those probe calls where add_disk() fails and clean up resources. We don't extend the probe call to return the error given: 1) we'd have to always special-case the case where the disk was already present, as otherwise concurrent requests to open an existing block device would fail, and this would be a userspace visible change 2) the error from ilookup() on blkdev_get_no_open() is sufficient 3) The only thing the probe call is used for is to support pre-devtmpfs, pre-udev semantics that want to create disks when their pre-created device node is accessed, and so we don't care for failures on probe there. Expand documentation for the probe callback to ensure users cleanup resources if add_disk() is used and to clarify this interface may be removed in the future. Reviewed-by: Christoph Hellwig Signed-off-by: Luis Chamberlain Link: https://lore.kernel.org/r/20211103230437.1639990-12-mcgrof@kernel.org Signed-off-by: Jens Axboe --- block/genhd.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'block') diff --git a/block/genhd.c b/block/genhd.c index 759bc06810f8..13494ed79675 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -212,7 +212,10 @@ void blkdev_show(struct seq_file *seqf, off_t offset) * @major: the requested major device number [1..BLKDEV_MAJOR_MAX-1]. If * @major = 0, try to allocate any unused major number. * @name: the name of the new block device as a zero terminated string - * @probe: allback that is called on access to any minor number of @major + * @probe: pre-devtmpfs / pre-udev callback used to create disks when their + * pre-created device node is accessed. When a probe call uses + * add_disk() and it fails the driver must cleanup resources. This + * interface may soon be removed. * * The @name must be unique within the system. * -- cgit v1.2.3