1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2010 Red Hat, Inc.
4 * Copyright (C) 2016-2023 Christoph Hellwig.
5 */
6#include <linux/iomap.h>
7#include <linux/pagemap.h>
8#include "internal.h"
9#include "trace.h"
10
11static void iomap_read_end_io(struct bio *bio)
12{
13 int error = blk_status_to_errno(status: bio->bi_status);
14 struct folio_iter fi;
15
16 bio_for_each_folio_all(fi, bio)
17 iomap_finish_folio_read(folio: fi.folio, off: fi.offset, len: fi.length, error);
18 bio_put(bio);
19}
20
21static void iomap_bio_submit_read(struct iomap_read_folio_ctx *ctx)
22{
23 struct bio *bio = ctx->read_ctx;
24
25 if (bio)
26 submit_bio(bio);
27}
28
29static int iomap_bio_read_folio_range(const struct iomap_iter *iter,
30 struct iomap_read_folio_ctx *ctx, size_t plen)
31{
32 struct folio *folio = ctx->cur_folio;
33 const struct iomap *iomap = &iter->iomap;
34 loff_t pos = iter->pos;
35 size_t poff = offset_in_folio(folio, pos);
36 loff_t length = iomap_length(iter);
37 sector_t sector;
38 struct bio *bio = ctx->read_ctx;
39
40 sector = iomap_sector(iomap, pos);
41 if (!bio || bio_end_sector(bio) != sector ||
42 !bio_add_folio(bio, folio, len: plen, off: poff)) {
43 gfp_t gfp = mapping_gfp_constraint(mapping: folio->mapping, GFP_KERNEL);
44 gfp_t orig_gfp = gfp;
45 unsigned int nr_vecs = DIV_ROUND_UP(length, PAGE_SIZE);
46
47 if (bio)
48 submit_bio(bio);
49
50 if (ctx->rac) /* same as readahead_gfp_mask */
51 gfp |= __GFP_NORETRY | __GFP_NOWARN;
52 bio = bio_alloc(bdev: iomap->bdev, nr_vecs: bio_max_segs(nr_segs: nr_vecs), opf: REQ_OP_READ,
53 gfp_mask: gfp);
54 /*
55 * If the bio_alloc fails, try it again for a single page to
56 * avoid having to deal with partial page reads. This emulates
57 * what do_mpage_read_folio does.
58 */
59 if (!bio)
60 bio = bio_alloc(bdev: iomap->bdev, nr_vecs: 1, opf: REQ_OP_READ, gfp_mask: orig_gfp);
61 if (ctx->rac)
62 bio->bi_opf |= REQ_RAHEAD;
63 bio->bi_iter.bi_sector = sector;
64 bio->bi_end_io = iomap_read_end_io;
65 bio_add_folio_nofail(bio, folio, len: plen, off: poff);
66 ctx->read_ctx = bio;
67 }
68 return 0;
69}
70
71const struct iomap_read_ops iomap_bio_read_ops = {
72 .read_folio_range = iomap_bio_read_folio_range,
73 .submit_read = iomap_bio_submit_read,
74};
75EXPORT_SYMBOL_GPL(iomap_bio_read_ops);
76
77int iomap_bio_read_folio_range_sync(const struct iomap_iter *iter,
78 struct folio *folio, loff_t pos, size_t len)
79{
80 const struct iomap *srcmap = iomap_iter_srcmap(i: iter);
81 struct bio_vec bvec;
82 struct bio bio;
83
84 bio_init(bio: &bio, bdev: srcmap->bdev, table: &bvec, max_vecs: 1, opf: REQ_OP_READ);
85 bio.bi_iter.bi_sector = iomap_sector(iomap: srcmap, pos);
86 bio_add_folio_nofail(bio: &bio, folio, len, offset_in_folio(folio, pos));
87 return submit_bio_wait(bio: &bio);
88}
89

source code of linux/fs/iomap/bio.c