diff options
authorLuis Chamberlain <>2021-11-03 16:04:34 -0700
committerJens Axboe <>2021-11-04 05:48:50 -0600
commit26e06f5b13671d194d67ae8e2b66f524ab174153 (patch)
parent4ddb85d36613c45bde00d368bf9f357bd0708a0c (diff)
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: Signed-off-by: Jens Axboe <>
1 files changed, 4 insertions, 1 deletions
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.