bdi: make inode_to_bdi() inline

Now that bdi definitions are moved to backing-dev-defs.h,
backing-dev.h can include blkdev.h and inline inode_to_bdi() without
worrying about introducing circular include dependency.  The function
gets called from hot paths and fairly trivial.

This patch makes inode_to_bdi() and sb_is_blkdev_sb() that the
function calls inline.  blockdev_superblock and noop_backing_dev_info
are EXPORT_GPL'd to allow the inline functions to be used from
modules.

While at it, make sb_is_blkdev_sb() return bool instead of int.

v2: Fixed typo in description as suggested by Jan.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

2 files changed, 2 insertions, 22 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index e545cbfbe5b2..f04c873a7365 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -547,7 +547,8 @@ static struct file_system_type bd_type = {
 	.kill_sb	= kill_anon_super,
 };
 
-static struct super_block *blockdev_superblock __read_mostly;
+struct super_block *blockdev_superblock __read_mostly;
+EXPORT_SYMBOL_GPL(blockdev_superblock);
 
 void __init bdev_cache_init(void)
 {
@@ -688,11 +689,6 @@ static struct block_device *bd_acquire(struct inode *inode)
 	return bdev;
 }
 
-int sb_is_blkdev_sb(struct super_block *sb)
-{
-	return sb == blockdev_superblock;
-}
-
 /* Call when you free inode */
 
 void bd_forget(struct inode *inode)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index a69d2e10d514..34d1cb854fc1 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -78,22 +78,6 @@ int writeback_in_progress(struct backing_dev_info *bdi)
 }
 EXPORT_SYMBOL(writeback_in_progress);
 
-struct backing_dev_info *inode_to_bdi(struct inode *inode)
-{
-	struct super_block *sb;
-
-	if (!inode)
-		return &noop_backing_dev_info;
-
-	sb = inode->i_sb;
-#ifdef CONFIG_BLOCK
-	if (sb_is_blkdev_sb(sb))
-		return blk_get_backing_dev_info(I_BDEV(inode));
-#endif
-	return sb->s_bdi;
-}
-EXPORT_SYMBOL_GPL(inode_to_bdi);
-
 static inline struct inode *wb_inode(struct list_head *head)
 {
 	return list_entry(head, struct inode, i_wb_list);