ceph: fix snap writeback when racing with writes

[pandora-kernel.git] / fs / block_dev.c

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 1a2421f..610e8e0 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -762,7 +762,19 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
        if (!disk)
                return ERR_PTR(-ENXIO);
 
-       whole = bdget_disk(disk, 0);
+       /*
+        * Normally, @bdev should equal what's returned from bdget_disk()
+        * if partno is 0; however, some drivers (floppy) use multiple
+        * bdev's for the same physical device and @bdev may be one of the
+        * aliases.  Keep @bdev if partno is 0.  This means claimer
+        * tracking is broken for those devices but it has always been that
+        * way.
+        */
+       if (partno)
+               whole = bdget_disk(disk, 0);
+       else
+               whole = bdgrab(bdev);
+
        module_put(disk->fops->owner);
        put_disk(disk);
        if (!whole)