The long if/else chain obsfucates the actual logic. Tidy it up to be
more structured. Also drop the whole argument, as it can be trivially
derived from bdev using bdev_whole, and having the bdev_whole in the
function makes it easier to follow.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
block/bdev.c | 40 ++++++++++++++++++++++------------------
1 file changed, 22 insertions(+), 18 deletions(-)
diff --git a/block/bdev.c b/block/bdev.c
index 317bfd9cba40fa..080b5c83bfbc72 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -463,7 +463,6 @@ long nr_blockdev_pages(void)
/**
* bd_may_claim - test whether a block device can be claimed
* @bdev: block device of interest
- * @whole: whole block device containing @bdev, may equal @bdev
* @holder: holder trying to claim @bdev
*
* Test whether @bdev can be claimed by @holder.
@@ -474,22 +473,27 @@ long nr_blockdev_pages(void)
* RETURNS:
* %true if @bdev can be claimed, %false otherwise.
*/
-static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
- void *holder)
+static bool bd_may_claim(struct block_device *bdev, void *holder)
{
- if (bdev->bd_holder == holder)
- return true; /* already a holder */
- else if (bdev->bd_holder != NULL)
- return false; /* held by someone else */
- else if (whole == bdev)
- return true; /* is a whole device which isn't held */
-
- else if (whole->bd_holder == bd_may_claim)
- return true; /* is a partition of a device that is being partitioned */
- else if (whole->bd_holder != NULL)
- return false; /* is a partition of a held device */
- else
- return true; /* is a partition of an un-held device */
+ struct block_device *whole = bdev_whole(bdev);
+
+ if (bdev->bd_holder) {
+ /*
+ * The same holder can always re-claim.
+ */
+ if (bdev->bd_holder == holder)
+ return true;
+ return false;
+ }
+
+ /*
+ * If the whole devices holder is set to bd_may_claim, a partition on
+ * the device is claimed, but not the whole device.
+ */
+ if (whole != bdev &&
+ whole->bd_holder && whole->bd_holder != bd_may_claim)
+ return false;
+ return true;
}
/**
@@ -513,7 +517,7 @@ int bd_prepare_to_claim(struct block_device *bdev, void *holder)
retry:
spin_lock(&bdev_lock);
/* if someone else claimed, fail */
- if (!bd_may_claim(bdev, whole, holder)) {
+ if (!bd_may_claim(bdev, holder)) {
spin_unlock(&bdev_lock);
return -EBUSY;
}
@@ -559,7 +563,7 @@ static void bd_finish_claiming(struct block_device *bdev, void *holder)
struct block_device *whole = bdev_whole(bdev);
spin_lock(&bdev_lock);
- BUG_ON(!bd_may_claim(bdev, whole, holder));
+ BUG_ON(!bd_may_claim(bdev, holder));
/*
* Note that for a whole device bd_holders will be incremented twice,
* and bd_holder will be set to bd_may_claim before being set to holder
--
2.39.2
