1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2018 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
5 */
6 #include <linux/module.h>
7 #include <linux/compiler.h>
8 #include <linux/fs.h>
9 #include <linux/iomap.h>
10 #include <linux/swap.h>
11
12 /* Swapfile activation */
13
14 struct iomap_swapfile_info {
15 struct iomap iomap; /* accumulated iomap */
16 struct swap_info_struct *sis;
17 uint64_t lowest_ppage; /* lowest physical addr seen (pages) */
18 uint64_t highest_ppage; /* highest physical addr seen (pages) */
19 unsigned long nr_pages; /* number of pages collected */
20 int nr_extents; /* extent count */
21 };
22
23 /*
24 * Collect physical extents for this swap file. Physical extents reported to
25 * the swap code must be trimmed to align to a page boundary. The logical
26 * offset within the file is irrelevant since the swapfile code maps logical
27 * page numbers of the swap device to the physical page-aligned extents.
28 */
iomap_swapfile_add_extent(struct iomap_swapfile_info * isi)29 static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
30 {
31 struct iomap *iomap = &isi->iomap;
32 unsigned long nr_pages;
33 uint64_t first_ppage;
34 uint64_t first_ppage_reported;
35 uint64_t next_ppage;
36 int error;
37
38 /*
39 * Round the start up and the end down so that the physical
40 * extent aligns to a page boundary.
41 */
42 first_ppage = ALIGN(iomap->addr, PAGE_SIZE) >> PAGE_SHIFT;
43 next_ppage = ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >>
44 PAGE_SHIFT;
45
46 /* Skip too-short physical extents. */
47 if (first_ppage >= next_ppage)
48 return 0;
49 nr_pages = next_ppage - first_ppage;
50
51 /*
52 * Calculate how much swap space we're adding; the first page contains
53 * the swap header and doesn't count. The mm still wants that first
54 * page fed to add_swap_extent, however.
55 */
56 first_ppage_reported = first_ppage;
57 if (iomap->offset == 0)
58 first_ppage_reported++;
59 if (isi->lowest_ppage > first_ppage_reported)
60 isi->lowest_ppage = first_ppage_reported;
61 if (isi->highest_ppage < (next_ppage - 1))
62 isi->highest_ppage = next_ppage - 1;
63
64 /* Add extent, set up for the next call. */
65 error = add_swap_extent(isi->sis, isi->nr_pages, nr_pages, first_ppage);
66 if (error < 0)
67 return error;
68 isi->nr_extents += error;
69 isi->nr_pages += nr_pages;
70 return 0;
71 }
72
73 /*
74 * Accumulate iomaps for this swap file. We have to accumulate iomaps because
75 * swap only cares about contiguous page-aligned physical extents and makes no
76 * distinction between written and unwritten extents.
77 */
iomap_swapfile_activate_actor(struct inode * inode,loff_t pos,loff_t count,void * data,struct iomap * iomap)78 static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
79 loff_t count, void *data, struct iomap *iomap)
80 {
81 struct iomap_swapfile_info *isi = data;
82 int error;
83
84 switch (iomap->type) {
85 case IOMAP_MAPPED:
86 case IOMAP_UNWRITTEN:
87 /* Only real or unwritten extents. */
88 break;
89 case IOMAP_INLINE:
90 /* No inline data. */
91 pr_err("swapon: file is inline\n");
92 return -EINVAL;
93 default:
94 pr_err("swapon: file has unallocated extents\n");
95 return -EINVAL;
96 }
97
98 /* No uncommitted metadata or shared blocks. */
99 if (iomap->flags & IOMAP_F_DIRTY) {
100 pr_err("swapon: file is not committed\n");
101 return -EINVAL;
102 }
103 if (iomap->flags & IOMAP_F_SHARED) {
104 pr_err("swapon: file has shared extents\n");
105 return -EINVAL;
106 }
107
108 /* Only one bdev per swap file. */
109 if (iomap->bdev != isi->sis->bdev) {
110 pr_err("swapon: file is on multiple devices\n");
111 return -EINVAL;
112 }
113
114 if (isi->iomap.length == 0) {
115 /* No accumulated extent, so just store it. */
116 memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
117 } else if (isi->iomap.addr + isi->iomap.length == iomap->addr) {
118 /* Append this to the accumulated extent. */
119 isi->iomap.length += iomap->length;
120 } else {
121 /* Otherwise, add the retained iomap and store this one. */
122 error = iomap_swapfile_add_extent(isi);
123 if (error)
124 return error;
125 memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
126 }
127 return count;
128 }
129
130 /*
131 * Iterate a swap file's iomaps to construct physical extents that can be
132 * passed to the swapfile subsystem.
133 */
iomap_swapfile_activate(struct swap_info_struct * sis,struct file * swap_file,sector_t * pagespan,const struct iomap_ops * ops)134 int iomap_swapfile_activate(struct swap_info_struct *sis,
135 struct file *swap_file, sector_t *pagespan,
136 const struct iomap_ops *ops)
137 {
138 struct iomap_swapfile_info isi = {
139 .sis = sis,
140 .lowest_ppage = (sector_t)-1ULL,
141 };
142 struct address_space *mapping = swap_file->f_mapping;
143 struct inode *inode = mapping->host;
144 loff_t pos = 0;
145 loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE);
146 loff_t ret;
147
148 /*
149 * Persist all file mapping metadata so that we won't have any
150 * IOMAP_F_DIRTY iomaps.
151 */
152 ret = vfs_fsync(swap_file, 1);
153 if (ret)
154 return ret;
155
156 while (len > 0) {
157 ret = iomap_apply(inode, pos, len, IOMAP_REPORT,
158 ops, &isi, iomap_swapfile_activate_actor);
159 if (ret <= 0)
160 return ret;
161
162 pos += ret;
163 len -= ret;
164 }
165
166 if (isi.iomap.length) {
167 ret = iomap_swapfile_add_extent(&isi);
168 if (ret)
169 return ret;
170 }
171
172 *pagespan = 1 + isi.highest_ppage - isi.lowest_ppage;
173 sis->max = isi.nr_pages;
174 sis->pages = isi.nr_pages - 1;
175 sis->highest_bit = isi.nr_pages - 1;
176 return isi.nr_extents;
177 }
178 EXPORT_SYMBOL_GPL(iomap_swapfile_activate);
179