Re: [PATCH 04/13] writeback: affine inode to a writeback ctx within a bdi

Christoph Hellwig
2025-06-02T14:24:09Z

On Thu, May 29, 2025 at 04:44:55PM +0530, Kundan Kumar wrote:
> @@ -157,7 +157,7 @@ fetch_bdi_writeback_ctx(struct inode *inode)
> {
> struct backing_dev_info *bdi = inode_to_bdi(inode);
>
> - return bdi->wb_ctx_arr[0];
> + return bdi->wb_ctx_arr[inode->i_ino % bdi->nr_wb_ctx];

Most modern file systems use 64-bit inode numbers, while i_ino sadly
still is only an ino_t that can be 32-bits wide. So we'll either need
an ugly fs hook here, or maybe convince Linus that it finally is time
for a 64-bit i_ino (which would also clean up a lot of mess in the
file systems and this constant source of confusion).