[2/6] block: inline BDEV_I and friends

Commit Message

Pavel Begunkov Oct. 9, 2021, 12:25 p.m. UTC

I_BDEV and BDEV_I are very simple, they worth a single arith instruction
or can even be almost completely compiled out. Inline them.

Signed-off-by: Pavel Begunkov <[e-mail]>
---
 block/bdev.c           | 16 ----------------
 include/linux/blkdev.h | 16 +++++++++++++++-
 2 files changed, 15 insertions(+), 17 deletions(-)

Comments

Christoph Hellwig Oct. 11, 2021, 8:20 a.m. UTC | #1

On Sat, Oct 09, 2021 at 01:25:39PM +0100, Pavel Begunkov wrote:
> I_BDEV and BDEV_I are very simple, they worth a single arith instruction
> or can even be almost completely compiled out. Inline them.

I see the benefit, but this is moving in the wrong direction.

struct bdev_inode is private to hide the struct inode.  Which at
the momen is a bit pointless given the bd_inode pointer in struct
block_device.

So we have two choices here that make sense:

 1) remove struct bdev_inode and kill the illusion that the inode
    is a private implementation detail
 2) remove direct references to bd_inode entirely.  Most of them are
    to i_size which already has proper helpers that should be used,
    and the rest can probably be covered with a handful wrappes or
    is bogus anyway

Patch

diff --git a/block/bdev.c b/block/bdev.c
index 567534c63f3d..a6cdfc49bc7e 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -30,22 +30,6 @@ 
 #include "../fs/internal.h"
 #include "blk.h"
 
-struct bdev_inode {
-	struct block_device bdev;
-	struct inode vfs_inode;
-};
-
-static inline struct bdev_inode *BDEV_I(struct inode *inode)
-{
-	return container_of(inode, struct bdev_inode, vfs_inode);
-}
-
-struct block_device *I_BDEV(struct inode *inode)
-{
-	return &BDEV_I(inode)->bdev;
-}
-EXPORT_SYMBOL(I_BDEV);
-
 static void bdev_write_inode(struct block_device *bdev)
 {
 	struct inode *inode = bdev->bd_inode;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4522acee81fb..591f14522f78 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1271,10 +1271,24 @@  void blkdev_put_no_open(struct block_device *bdev);
 
 struct block_device *bdev_alloc(struct gendisk *disk, u8 partno);
 void bdev_add(struct block_device *bdev, dev_t dev);
-struct block_device *I_BDEV(struct inode *inode);
 int truncate_bdev_range(struct block_device *bdev, fmode_t mode, loff_t lstart,
 		loff_t lend);
 
+struct bdev_inode {
+	struct block_device bdev;
+	struct inode vfs_inode;
+};
+
+static inline struct bdev_inode *BDEV_I(struct inode *inode)
+{
+	return container_of(inode, struct bdev_inode, vfs_inode);
+}
+
+static inline struct block_device *I_BDEV(struct inode *inode)
+{
+	return &BDEV_I(inode)->bdev;
+}
+
 #ifdef CONFIG_BLOCK
 void invalidate_bdev(struct block_device *bdev);
 int sync_blockdev(struct block_device *bdev);