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 static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi) 31 { 32 struct iomap *iomap = &isi->iomap; 33 unsigned long nr_pages; 34 uint64_t first_ppage; 35 uint64_t first_ppage_reported; 36 uint64_t next_ppage; 37 int error; 38 39 /* 40 * Round the start up and the end down so that the physical 41 * extent aligns to a page boundary. 42 */ 43 first_ppage = ALIGN(iomap->addr, PAGE_SIZE) >> PAGE_SHIFT; 44 next_ppage = ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >> 45 PAGE_SHIFT; 46 47 /* Skip too-short physical extents. */ 48 if (first_ppage >= next_ppage) 49 return 0; 50 nr_pages = next_ppage - first_ppage; 51 52 /* 53 * Calculate how much swap space we're adding; the first page contains 54 * the swap header and doesn't count. The mm still wants that first 55 * page fed to add_swap_extent, however. 56 */ 57 first_ppage_reported = first_ppage; 58 if (iomap->offset == 0) 59 first_ppage_reported++; 60 if (isi->lowest_ppage > first_ppage_reported) 61 isi->lowest_ppage = first_ppage_reported; 62 if (isi->highest_ppage < (next_ppage - 1)) 63 isi->highest_ppage = next_ppage - 1; 64 65 /* Add extent, set up for the next call. */ 66 error = add_swap_extent(isi->sis, isi->nr_pages, nr_pages, first_ppage); 67 if (error < 0) 68 return error; 69 isi->nr_extents += error; 70 isi->nr_pages += nr_pages; 71 return 0; 72 } 73 74 static int iomap_swapfile_fail(struct iomap_swapfile_info *isi, const char *str) 75 { 76 char *buf, *p = ERR_PTR(-ENOMEM); 77 78 buf = kmalloc(PATH_MAX, GFP_KERNEL); 79 if (buf) 80 p = file_path(isi->file, buf, PATH_MAX); 81 pr_err("swapon: file %s %s\n", IS_ERR(p) ? "<unknown>" : p, str); 82 kfree(buf); 83 return -EINVAL; 84 } 85 86 /* 87 * Accumulate iomaps for this swap file. We have to accumulate iomaps because 88 * swap only cares about contiguous page-aligned physical extents and makes no 89 * distinction between written and unwritten extents. 90 */ 91 static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos, 92 loff_t count, void *data, struct iomap *iomap, 93 struct iomap *srcmap) 94 { 95 struct iomap_swapfile_info *isi = data; 96 int error; 97 98 switch (iomap->type) { 99 case IOMAP_MAPPED: 100 case IOMAP_UNWRITTEN: 101 /* Only real or unwritten extents. */ 102 break; 103 case IOMAP_INLINE: 104 /* No inline data. */ 105 return iomap_swapfile_fail(isi, "is inline"); 106 default: 107 return iomap_swapfile_fail(isi, "has unallocated extents"); 108 } 109 110 /* No uncommitted metadata or shared blocks. */ 111 if (iomap->flags & IOMAP_F_DIRTY) 112 return iomap_swapfile_fail(isi, "is not committed"); 113 if (iomap->flags & IOMAP_F_SHARED) 114 return iomap_swapfile_fail(isi, "has shared extents"); 115 116 /* Only one bdev per swap file. */ 117 if (iomap->bdev != isi->sis->bdev) 118 return iomap_swapfile_fail(isi, "outside the main device"); 119 120 if (isi->iomap.length == 0) { 121 /* No accumulated extent, so just store it. */ 122 memcpy(&isi->iomap, iomap, sizeof(isi->iomap)); 123 } else if (isi->iomap.addr + isi->iomap.length == iomap->addr) { 124 /* Append this to the accumulated extent. */ 125 isi->iomap.length += iomap->length; 126 } else { 127 /* Otherwise, add the retained iomap and store this one. */ 128 error = iomap_swapfile_add_extent(isi); 129 if (error) 130 return error; 131 memcpy(&isi->iomap, iomap, sizeof(isi->iomap)); 132 } 133 return count; 134 } 135 136 /* 137 * Iterate a swap file's iomaps to construct physical extents that can be 138 * passed to the swapfile subsystem. 139 */ 140 int iomap_swapfile_activate(struct swap_info_struct *sis, 141 struct file *swap_file, sector_t *pagespan, 142 const struct iomap_ops *ops) 143 { 144 struct iomap_swapfile_info isi = { 145 .sis = sis, 146 .lowest_ppage = (sector_t)-1ULL, 147 .file = swap_file, 148 }; 149 struct address_space *mapping = swap_file->f_mapping; 150 struct inode *inode = mapping->host; 151 loff_t pos = 0; 152 loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE); 153 loff_t ret; 154 155 /* 156 * Persist all file mapping metadata so that we won't have any 157 * IOMAP_F_DIRTY iomaps. 158 */ 159 ret = vfs_fsync(swap_file, 1); 160 if (ret) 161 return ret; 162 163 while (len > 0) { 164 ret = iomap_apply(inode, pos, len, IOMAP_REPORT, 165 ops, &isi, iomap_swapfile_activate_actor); 166 if (ret <= 0) 167 return ret; 168 169 pos += ret; 170 len -= ret; 171 } 172 173 if (isi.iomap.length) { 174 ret = iomap_swapfile_add_extent(&isi); 175 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 if (isi.nr_pages == 0) { 185 pr_warn("swapon: Cannot find a single usable page in file.\n"); 186 return -EINVAL; 187 } 188 189 *pagespan = 1 + isi.highest_ppage - isi.lowest_ppage; 190 sis->max = isi.nr_pages; 191 sis->pages = isi.nr_pages - 1; 192 sis->highest_bit = isi.nr_pages - 1; 193 return isi.nr_extents; 194 } 195 EXPORT_SYMBOL_GPL(iomap_swapfile_activate); 196