1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2010 Red Hat, Inc.
4 * Copyright (c) 2016-2021 Christoph Hellwig.
5 */
6#include <linux/iomap.h>
7#include "trace.h"
8
9static inline void iomap_iter_reset_iomap(struct iomap_iter *iter)
10{
11 iter->status = 0;
12 memset(s: &iter->iomap, c: 0, n: sizeof(iter->iomap));
13 memset(s: &iter->srcmap, c: 0, n: sizeof(iter->srcmap));
14}
15
16/*
17 * Advance the current iterator position and output the length remaining for the
18 * current mapping.
19 */
20int iomap_iter_advance(struct iomap_iter *iter, u64 *count)
21{
22 if (WARN_ON_ONCE(*count > iomap_length(iter)))
23 return -EIO;
24 iter->pos += *count;
25 iter->len -= *count;
26 *count = iomap_length(iter);
27 return 0;
28}
29
30static inline void iomap_iter_done(struct iomap_iter *iter)
31{
32 WARN_ON_ONCE(iter->iomap.offset > iter->pos);
33 WARN_ON_ONCE(iter->iomap.length == 0);
34 WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
35 WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_STALE);
36
37 iter->iter_start_pos = iter->pos;
38
39 trace_iomap_iter_dstmap(inode: iter->inode, iomap: &iter->iomap);
40 if (iter->srcmap.type != IOMAP_HOLE)
41 trace_iomap_iter_srcmap(inode: iter->inode, iomap: &iter->srcmap);
42}
43
44/**
45 * iomap_iter - iterate over a ranges in a file
46 * @iter: iteration structue
47 * @ops: iomap ops provided by the file system
48 *
49 * Iterate over filesystem-provided space mappings for the provided file range.
50 *
51 * This function handles cleanup of resources acquired for iteration when the
52 * filesystem indicates there are no more space mappings, which means that this
53 * function must be called in a loop that continues as long it returns a
54 * positive value. If 0 or a negative value is returned, the caller must not
55 * return to the loop body. Within a loop body, there are two ways to break out
56 * of the loop body: leave @iter.status unchanged, or set it to a negative
57 * errno.
58 */
59int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
60{
61 bool stale = iter->iomap.flags & IOMAP_F_STALE;
62 ssize_t advanced;
63 u64 olen;
64 int ret;
65
66 trace_iomap_iter(iter, ops, _RET_IP_);
67
68 if (!iter->iomap.length)
69 goto begin;
70
71 /*
72 * Calculate how far the iter was advanced and the original length bytes
73 * for ->iomap_end().
74 */
75 advanced = iter->pos - iter->iter_start_pos;
76 olen = iter->len + advanced;
77
78 if (ops->iomap_end) {
79 ret = ops->iomap_end(iter->inode, iter->iter_start_pos,
80 iomap_length_trim(iter, pos: iter->iter_start_pos,
81 len: olen),
82 advanced, iter->flags, &iter->iomap);
83 if (ret < 0 && !advanced)
84 return ret;
85 }
86
87 /* detect old return semantics where this would advance */
88 if (WARN_ON_ONCE(iter->status > 0))
89 iter->status = -EIO;
90
91 /*
92 * Use iter->len to determine whether to continue onto the next mapping.
93 * Explicitly terminate on error status or if the current iter has not
94 * advanced at all (i.e. no work was done for some reason) unless the
95 * mapping has been marked stale and needs to be reprocessed.
96 */
97 if (iter->status < 0)
98 ret = iter->status;
99 else if (iter->len == 0 || (!advanced && !stale))
100 ret = 0;
101 else
102 ret = 1;
103 iomap_iter_reset_iomap(iter);
104 if (ret <= 0)
105 return ret;
106
107begin:
108 ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
109 &iter->iomap, &iter->srcmap);
110 if (ret < 0)
111 return ret;
112 iomap_iter_done(iter);
113 return 1;
114}
115