On Mon, Dec 09, 2024 at 10:20:33AM +0800, Yang Erkun wrote:
> Before commit e418de3abcda ("block: switch gendisk lookup to a simple
> xarray"), open loop0 will success. lookup_gendisk will first use
> base_probe to load module loop, and then the retry will call loop_probe
> to prepare the loop disk. Finally open for this disk will success.
> However, after this commit, we lose the retry logic, and open will fail
> with ENXIO. Block device autoloading is deprecated and will be removed
> soon, but maybe we should keep open success until we really remove it.
> So, give a retry to fix it.
This looks sensible. But can we clean the logic up a bit by adding
a helper to make it easier to understand? Something like the untested
patch below:
diff --git a/block/genhd.c b/block/genhd.c
index 6fcb09b8371d..654c2cc5d8e5 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -797,7 +797,7 @@ static ssize_t disk_badblocks_store(struct device *dev,
}
#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
-void blk_request_module(dev_t devt)
+static bool blk_probe_dev(dev_t devt)
{
unsigned int major = MAJOR(devt);
struct blk_major_name **n;
@@ -807,14 +807,26 @@ void blk_request_module(dev_t devt)
if ((*n)->major == major && (*n)->probe) {
(*n)->probe(devt);
mutex_unlock(&major_names_lock);
- return;
+ return true;
}
}
mutex_unlock(&major_names_lock);
+ return false;
+}
+
+void blk_request_module(dev_t devt)
+{
+ int error;
+
+ if (blk_probe_dev(devt))
+ return;
- if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0)
- /* Make old-style 2.4 aliases work */
- request_module("block-major-%d", MAJOR(devt));
+ error = request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt));
+ /* Make old-style 2.4 aliases work */
+ if (error > 0)
+ error = request_module("block-major-%d", MAJOR(devt));
+ if (!error)
+ blk_probe_dev(devt);
}
#endif /* CONFIG_BLOCK_LEGACY_AUTOLOAD */
