Line data Source code
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 : struct file *file;
22 : };
23 :
24 : /*
25 : * Collect physical extents for this swap file. Physical extents reported to
26 : * the swap code must be trimmed to align to a page boundary. The logical
27 : * offset within the file is irrelevant since the swapfile code maps logical
28 : * page numbers of the swap device to the physical page-aligned extents.
29 : */
30 86 : static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
31 : {
32 86 : struct iomap *iomap = &isi->iomap;
33 86 : unsigned long nr_pages;
34 86 : unsigned long max_pages;
35 86 : uint64_t first_ppage;
36 86 : uint64_t first_ppage_reported;
37 86 : uint64_t next_ppage;
38 86 : int error;
39 :
40 86 : if (unlikely(isi->nr_pages >= isi->sis->max))
41 : return 0;
42 86 : max_pages = isi->sis->max - isi->nr_pages;
43 :
44 : /*
45 : * Round the start up and the end down so that the physical
46 : * extent aligns to a page boundary.
47 : */
48 86 : first_ppage = ALIGN(iomap->addr, PAGE_SIZE) >> PAGE_SHIFT;
49 86 : next_ppage = ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >>
50 : PAGE_SHIFT;
51 :
52 : /* Skip too-short physical extents. */
53 86 : if (first_ppage >= next_ppage)
54 : return 0;
55 62 : nr_pages = next_ppage - first_ppage;
56 62 : nr_pages = min(nr_pages, max_pages);
57 :
58 : /*
59 : * Calculate how much swap space we're adding; the first page contains
60 : * the swap header and doesn't count. The mm still wants that first
61 : * page fed to add_swap_extent, however.
62 : */
63 62 : first_ppage_reported = first_ppage;
64 62 : if (iomap->offset == 0)
65 60 : first_ppage_reported++;
66 62 : if (isi->lowest_ppage > first_ppage_reported)
67 60 : isi->lowest_ppage = first_ppage_reported;
68 62 : if (isi->highest_ppage < (next_ppage - 1))
69 62 : isi->highest_ppage = next_ppage - 1;
70 :
71 : /* Add extent, set up for the next call. */
72 62 : error = add_swap_extent(isi->sis, isi->nr_pages, nr_pages, first_ppage);
73 62 : if (error < 0)
74 : return error;
75 62 : isi->nr_extents += error;
76 62 : isi->nr_pages += nr_pages;
77 62 : return 0;
78 : }
79 :
80 2 : static int iomap_swapfile_fail(struct iomap_swapfile_info *isi, const char *str)
81 : {
82 2 : char *buf, *p = ERR_PTR(-ENOMEM);
83 :
84 2 : buf = kmalloc(PATH_MAX, GFP_KERNEL);
85 2 : if (buf)
86 2 : p = file_path(isi->file, buf, PATH_MAX);
87 2 : pr_err("swapon: file %s %s\n", IS_ERR(p) ? "<unknown>" : p, str);
88 2 : kfree(buf);
89 2 : return -EINVAL;
90 : }
91 :
92 : /*
93 : * Accumulate iomaps for this swap file. We have to accumulate iomaps because
94 : * swap only cares about contiguous page-aligned physical extents and makes no
95 : * distinction between written and unwritten extents.
96 : */
97 152 : static loff_t iomap_swapfile_iter(const struct iomap_iter *iter,
98 : struct iomap *iomap, struct iomap_swapfile_info *isi)
99 : {
100 152 : switch (iomap->type) {
101 : case IOMAP_MAPPED:
102 : case IOMAP_UNWRITTEN:
103 : /* Only real or unwritten extents. */
104 152 : break;
105 0 : case IOMAP_INLINE:
106 : /* No inline data. */
107 0 : return iomap_swapfile_fail(isi, "is inline");
108 0 : default:
109 0 : return iomap_swapfile_fail(isi, "has unallocated extents");
110 : }
111 :
112 : /* No uncommitted metadata or shared blocks. */
113 152 : if (iomap->flags & IOMAP_F_DIRTY)
114 0 : return iomap_swapfile_fail(isi, "is not committed");
115 152 : if (iomap->flags & IOMAP_F_SHARED)
116 2 : return iomap_swapfile_fail(isi, "has shared extents");
117 :
118 : /* Only one bdev per swap file. */
119 150 : if (iomap->bdev != isi->sis->bdev)
120 0 : return iomap_swapfile_fail(isi, "outside the main device");
121 :
122 150 : if (isi->iomap.length == 0) {
123 : /* No accumulated extent, so just store it. */
124 124 : memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
125 88 : } else if (isi->iomap.addr + isi->iomap.length == iomap->addr) {
126 : /* Append this to the accumulated extent. */
127 64 : isi->iomap.length += iomap->length;
128 : } else {
129 : /* Otherwise, add the retained iomap and store this one. */
130 24 : int error = iomap_swapfile_add_extent(isi);
131 24 : if (error)
132 0 : return error;
133 48 : memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
134 : }
135 150 : return iomap_length(iter);
136 : }
137 :
138 : /*
139 : * Iterate a swap file's iomaps to construct physical extents that can be
140 : * passed to the swapfile subsystem.
141 : */
142 64 : int iomap_swapfile_activate(struct swap_info_struct *sis,
143 : struct file *swap_file, sector_t *pagespan,
144 : const struct iomap_ops *ops)
145 : {
146 64 : struct inode *inode = swap_file->f_mapping->host;
147 64 : struct iomap_iter iter = {
148 : .inode = inode,
149 : .pos = 0,
150 64 : .len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE),
151 : .flags = IOMAP_REPORT,
152 : };
153 64 : struct iomap_swapfile_info isi = {
154 : .sis = sis,
155 : .lowest_ppage = (sector_t)-1ULL,
156 : .file = swap_file,
157 : };
158 64 : int ret;
159 :
160 : /*
161 : * Persist all file mapping metadata so that we won't have any
162 : * IOMAP_F_DIRTY iomaps.
163 : */
164 64 : ret = vfs_fsync(swap_file, 1);
165 64 : if (ret)
166 : return ret;
167 :
168 216 : while ((ret = iomap_iter(&iter, ops)) > 0)
169 152 : iter.processed = iomap_swapfile_iter(&iter, &iter.iomap, &isi);
170 64 : if (ret < 0)
171 : return ret;
172 :
173 62 : if (isi.iomap.length) {
174 62 : ret = iomap_swapfile_add_extent(&isi);
175 62 : if (ret)
176 : return ret;
177 : }
178 :
179 : /*
180 : * If this swapfile doesn't contain even a single page-aligned
181 : * contiguous range of blocks, reject this useless swapfile to
182 : * prevent confusion later on.
183 : */
184 62 : if (isi.nr_pages == 0) {
185 2 : pr_warn("swapon: Cannot find a single usable page in file.\n");
186 2 : return -EINVAL;
187 : }
188 :
189 60 : *pagespan = 1 + isi.highest_ppage - isi.lowest_ppage;
190 60 : sis->max = isi.nr_pages;
191 60 : sis->pages = isi.nr_pages - 1;
192 60 : sis->highest_bit = isi.nr_pages - 1;
193 60 : return isi.nr_extents;
194 : }
195 : EXPORT_SYMBOL_GPL(iomap_swapfile_activate);
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