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/fs.h>
7 #include <linux/iomap.h>
8 #include "trace.h"
9
iomap_iter_reset_iomap(struct iomap_iter * iter)10 static inline void iomap_iter_reset_iomap(struct iomap_iter *iter)
11 {
12 iter->status = 0;
13 memset(&iter->iomap, 0, sizeof(iter->iomap));
14 memset(&iter->srcmap, 0, sizeof(iter->srcmap));
15 }
16
17 /*
18 * Advance the current iterator position and output the length remaining for the
19 * current mapping.
20 */
iomap_iter_advance(struct iomap_iter * iter,u64 * count)21 int iomap_iter_advance(struct iomap_iter *iter, u64 *count)
22 {
23 if (WARN_ON_ONCE(*count > iomap_length(iter)))
24 return -EIO;
25 iter->pos += *count;
26 iter->len -= *count;
27 *count = iomap_length(iter);
28 return 0;
29 }
30
iomap_iter_done(struct iomap_iter * iter)31 static inline void iomap_iter_done(struct iomap_iter *iter)
32 {
33 WARN_ON_ONCE(iter->iomap.offset > iter->pos);
34 WARN_ON_ONCE(iter->iomap.length == 0);
35 WARN_ON_ONCE(iter->iomap.offset + iter->iomap.length <= iter->pos);
36 WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_STALE);
37
38 iter->iter_start_pos = iter->pos;
39
40 trace_iomap_iter_dstmap(iter->inode, &iter->iomap);
41 if (iter->srcmap.type != IOMAP_HOLE)
42 trace_iomap_iter_srcmap(iter->inode, &iter->srcmap);
43 }
44
45 /**
46 * iomap_iter - iterate over a ranges in a file
47 * @iter: iteration structue
48 * @ops: iomap ops provided by the file system
49 *
50 * Iterate over filesystem-provided space mappings for the provided file range.
51 *
52 * This function handles cleanup of resources acquired for iteration when the
53 * filesystem indicates there are no more space mappings, which means that this
54 * function must be called in a loop that continues as long it returns a
55 * positive value. If 0 or a negative value is returned, the caller must not
56 * return to the loop body. Within a loop body, there are two ways to break out
57 * of the loop body: leave @iter.status unchanged, or set it to a negative
58 * errno.
59 */
iomap_iter(struct iomap_iter * iter,const struct iomap_ops * ops)60 int iomap_iter(struct iomap_iter *iter, const struct iomap_ops *ops)
61 {
62 bool stale = iter->iomap.flags & IOMAP_F_STALE;
63 ssize_t advanced;
64 u64 olen;
65 int ret;
66
67 trace_iomap_iter(iter, ops, _RET_IP_);
68
69 if (!iter->iomap.length)
70 goto begin;
71
72 /*
73 * Calculate how far the iter was advanced and the original length bytes
74 * for ->iomap_end().
75 */
76 advanced = iter->pos - iter->iter_start_pos;
77 olen = iter->len + advanced;
78
79 if (ops->iomap_end) {
80 ret = ops->iomap_end(iter->inode, iter->iter_start_pos,
81 iomap_length_trim(iter, iter->iter_start_pos,
82 olen),
83 advanced, iter->flags, &iter->iomap);
84 if (ret < 0 && !advanced)
85 return ret;
86 }
87
88 /* detect old return semantics where this would advance */
89 if (WARN_ON_ONCE(iter->status > 0))
90 iter->status = -EIO;
91
92 /*
93 * Use iter->len to determine whether to continue onto the next mapping.
94 * Explicitly terminate on error status or if the current iter has not
95 * advanced at all (i.e. no work was done for some reason) unless the
96 * mapping has been marked stale and needs to be reprocessed.
97 */
98 if (iter->status < 0)
99 ret = iter->status;
100 else if (iter->len == 0 || (!advanced && !stale))
101 ret = 0;
102 else
103 ret = 1;
104 iomap_iter_reset_iomap(iter);
105 if (ret <= 0)
106 return ret;
107
108 begin:
109 ret = ops->iomap_begin(iter->inode, iter->pos, iter->len, iter->flags,
110 &iter->iomap, &iter->srcmap);
111 if (ret < 0)
112 return ret;
113 iomap_iter_done(iter);
114 return 1;
115 }
116