On Sat, Oct 05, 2024 at 03:20:06AM +0100, Matthew Wilcox wrote:
> On Fri, Oct 04, 2024 at 04:04:29PM -0400, Goldwyn Rodrigues wrote:
> > iomap_read_folio_ops provide additional functions to allocate or submit
> > the bio. Filesystems such as btrfs have additional operations with bios
> > such as verifying data checksums. Creating a bio submission hook allows
> > the filesystem to process and verify the bio.
>
> But surely you're going to need something similar for writeback too?
> So why go to all this trouble to add a new kind of ops instead of making
> it part of iomap_ops or iomap_folio_ops?
iomap_folio_ops, and maybe it's time to rename it iomap_pagecache_ops.
I almost wonder if we should have this instead:
struct iomap_pagecache_ops {
struct iomap_ops ops;
/* folio management */
struct folio *(*get_folio)(struct iomap_iter *iter, loff_t pos,
unsigned len);
void (*put_folio)(struct inode *inode, loff_t pos, unsigned copied,
struct folio *folio);
/* mapping revalidation */
bool (*iomap_valid)(struct inode *inode, const struct iomap *iomap);
/* writeback */
int (*map_blocks)(struct iomap_writepage_ctx *wpc, struct inode *inode,
loff_t offset, unsigned len);
int (*prepare_ioend)(struct iomap_ioend *ioend, int status);
void (*discard_folio)(struct folio *folio, loff_t pos);
};
and then we change the buffered-io.c functions to take a (const struct
iomap_pagecache_ops*) instead of iomap_ops+iomap_folio_ops, or
iomap_ops+iomap_writeback_ops.
Same embedding suggestion for iomap_dio_ops.
--D
