On Tue, Jul 20, 2021 at 10:43:19AM +0200, Christoph Hellwig wrote:
> Now that the outstanding reads are counted in bytes, there is no need
> to use the low-level __bio_try_merge_page API, we can switch back to
> always using bio_add_page and simply iomap_readpage_actor again.
I don't think this quite works. You need to check the return value
from bio_add_page(), otherwise you can be in a situation where you try
to add a page to the last bvec and it's not contiguous, so it fails.
I was imagining something more like this:
- bool same_page = false, is_contig = false;
+ bool is_contig = false;
...
/* Try to merge into a previous segment if we can */
sector = iomap_sector(iomap, pos);
- if (ctx->bio && bio_end_sector(ctx->bio) == sector) {
- if (__bio_try_merge_page(ctx->bio, page, plen, poff,
- &same_page))
- goto done;
- is_contig = true;
- }
+ if (ctx->bio && bio_end_sector(ctx->bio) == sector)
+ is_contig = bio_add_page(ctx->bio, page, plen, poff) > 0;
- if (!is_contig || bio_full(ctx->bio, plen)) {
+ if (!is_contig) {
gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
gfp_t orig_gfp = gfp;
...
bio_set_dev(ctx->bio, iomap->bdev);
ctx->bio->bi_end_io = iomap_read_end_io;
+ bio_add_page(ctx->bio, page, plen, poff);
}
- bio_add_page(ctx->bio, page, plen, poff);
done:
/*
