[PATCH] fs-private data in struct block_device

[Christoph Hellwig <hch@lst.de>]

Al had some critism about a per-blockdev XFS datastructure a while ago
and so I tried to follow the suggestion in favour of using struct
block_device directly.  Unfortunately XFS requires a little bit more
information than what's available in struct block_device, in particular
whether the blocksize (not sector size) for that devices is identical
to the page size, and we can't really get that from elsewhere due to
layering constraints.

Nathan Scott scott suggested turning the bd_invalidated fields into a
flags field where the filesystem uses the so far unused flags for it's
purposed (similar to struct buffer_head), but I think maybe the variant
below that just adds a unsigned long for filesystem usage might be more
useful as it also allows storing a pointer if needed.  Comments?


--- 1.276/include/linux/fs.h	Mon Dec 29 22:37:20 2003
+++ edited/include/linux/fs.h	Thu Jan  1 13:42:08 2004
@@ -353,6 +353,7 @@
 	int			bd_invalidated;
 	struct gendisk *	bd_disk;
 	struct list_head	bd_list;
+	unsigned long		bd_fspriv; /* file-system private data */
 };
 
 /*