[RFC] vfs/inode: For none-block-based filesystems default to sb->s_bdi

[Boaz Harrosh <bharrosh@panasas.com>]

In alloc_inode (inode_init_always) in the case that sb->s_bdev
is NULL. Should we not use sb->s_bdi as the default
mapping->backing_dev_info?

This fixes my none-block-based filesystem recent WARN_ON
at fs/fs-writeback.c:87 inode_to_bdi()

If not done here I'll need to do this in 5 different cases
in FS code. (OK the code could enjoy some re-factoring).

It does look logical the question is how many FSs will now
get broken?

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
---
 fs/inode.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/fs/inode.c b/fs/inode.c
index 8646433..200314f 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -181,6 +181,8 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
 
 		bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
 		mapping->backing_dev_info = bdi;
+	} else {
+		mapping->backing_dev_info = sb->s_bdi;
 	}
 	inode->i_private = NULL;
 	inode->i_mapping = mapping;
-- 
1.7.2