On Thu, Dec 12, 2024 at 11:51:49AM -0800, Darrick J. Wong wrote:
> > +struct iomap_ioend *iomap_split_ioend(struct iomap_ioend *ioend, bool is_append,
>
> Can you determine is_append from (ioend->io_flags & ZONE_APPEND)?
That would require us to add that flag first :) As we don't really
need that as persistent per-iomap that it's probably not worth it.
> Also it's not clear to me what the initial and output state of
> *alloc_len is supposed to be? I guess you set it to the number of bytes
> the @ioend covers?
It gets set to the number of blocks that the allocator could find,
and iomap_split_ioend decrements the amount of that it used for the
ioend returned, which is min(*alloc_len, max_zone_append_sectors) for
sequential zones, or *alloc_len for conventional zones.
> > +++ b/include/linux/iomap.h
> > @@ -354,6 +354,9 @@ struct iomap_ioend {
> > struct list_head io_list; /* next ioend in chain */
> > u16 io_flags; /* IOMAP_IOEND_* */
> > struct inode *io_inode; /* file being written to */
> > + atomic_t io_remaining; /* completetion defer count */
> > + int io_error; /* stashed away status */
> > + struct iomap_ioend *io_parent; /* parent for completions */
>
> I guess this means ioends can chain together, sort of like how bios can
> when you split them?
Exactly.
