Add caller-provided callbacks for read and readahead so that it can be
used generically, especially by filesystems that are not block-based.
In particular, this:
* Modifies the read and readahead interface to take in a
struct iomap_read_folio_ctx that is publicly defined as:
struct iomap_read_folio_ctx {
const struct iomap_read_ops *ops;
struct folio *cur_folio;
struct readahead_control *rac;
void *read_ctx;
};
where struct iomap_read_ops is defined as:
struct iomap_read_ops {
int (*read_folio_range)(const struct iomap_iter *iter,
struct iomap_read_folio_ctx *ctx,
size_t len);
void (*read_submit)(struct iomap_read_folio_ctx *ctx);
};
read_folio_range() reads in the folio range and is required by the
caller to provide. read_submit() is optional and is used for
submitting any pending read requests.
* Modifies existing filesystems that use iomap for read and readahead to
use the new API, through the new statically inlined helpers
iomap_bio_read_folio() and iomap_bio_readahead(). There is no change
in functionality for those filesystems.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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