On Sat, Nov 25, 2023 at 05:39:12PM +0800, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> block_devcie is allocated from bdev_alloc() by bdev_alloc_inode(), and
> currently block_device contains a pointer that point to the address of
> inode, while such inode is allocated together:
>
> bdev_alloc
> inode = new_inode()
> // inode is &bdev_inode->vfs_inode
> bdev = I_BDEV(inode)
> // bdev is &bdev_inode->bdev
> bdev->inode = inode
>
> Add a new helper to get address of inode from bdev by add operation
> instead of memory access, which is more efficiency. Also prepare to
> add a new field 'bd_flags' in the first cacheline(64 bytes).
>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> ---
> block/bdev.c | 39 +++++++++++++++++-------------
> block/blk-zoned.c | 4 +--
> block/fops.c | 4 +--
> block/genhd.c | 8 +++---
> block/ioctl.c | 8 +++---
> block/partitions/core.c | 9 ++++---
> drivers/block/xen-blkback/xenbus.c | 2 +-
> drivers/md/bcache/super.c | 2 +-
> drivers/mtd/devices/block2mtd.c | 12 ++++-----
> drivers/s390/block/dasd_ioctl.c | 2 +-
> drivers/scsi/scsicam.c | 2 +-
> fs/bcachefs/util.h | 2 +-
> fs/btrfs/disk-io.c | 6 ++---
> fs/btrfs/volumes.c | 4 +--
> fs/btrfs/zoned.c | 2 +-
> fs/buffer.c | 8 +++---
> fs/cramfs/inode.c | 2 +-
> fs/erofs/data.c | 2 +-
> fs/ext4/dir.c | 2 +-
> fs/ext4/ext4_jbd2.c | 2 +-
> fs/ext4/super.c | 8 +++---
> fs/gfs2/glock.c | 2 +-
> fs/gfs2/ops_fstype.c | 2 +-
> fs/jbd2/journal.c | 3 ++-
> fs/jbd2/recovery.c | 2 +-
> fs/nilfs2/segment.c | 2 +-
> include/linux/blk_types.h | 10 ++++++--
> include/linux/blkdev.h | 4 +--
> include/linux/buffer_head.h | 4 +--
> 29 files changed, 86 insertions(+), 73 deletions(-)
You should do this as a patch series, add the helper function that does
nothing, convert all the different portions of the kernel as different
patches, and _then_ change the implementation of the block layer to
handle the change in the structure.
Otherwise this is going to be hard to get accepted.
Also, one note:
> @@ -85,6 +84,13 @@ struct block_device {
> #define bdev_kobj(_bdev) \
> (&((_bdev)->bd_device.kobj))
>
> +static inline struct inode *bdev_inode(struct block_device *bdev)
> +{
> + void *inode = bdev + 1;
That's crazy, if something changes, this will keep working yet the
kernel will break and no one will know why.
Please use container_of(), that's what it is there for, this exact type
of thing. Or if not, are you just assuming that the memory location
right after bdev is the inode? That's a tough assumption, how are you
going to assure it really stays there?
thanks,
greg k-h
