[PATCH 16/45] block: switch bdgrab to use igrab

[Christoph Hellwig]

All of the current callers already have a reference, but to prepare for
additional users ensure bdgrab returns NULL if the block device is beeing
freed.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 fs/block_dev.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index d707ab376da86e..962fabe8a67b83 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -894,10 +894,14 @@ static struct block_device *bdget(dev_t dev)
 /**
  * bdgrab -- Grab a reference to an already referenced block device
  * @bdev:	Block device to grab a reference to.
+ *
+ * Returns the block_device with an additional reference when successful,
+ * or NULL if the inode is already beeing freed.
  */
 struct block_device *bdgrab(struct block_device *bdev)
 {
-	ihold(bdev->bd_inode);
+	if (!igrab(bdev->bd_inode))
+		return NULL;
 	return bdev;
 }
 EXPORT_SYMBOL(bdgrab);
-- 
2.29.2