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 */ 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 */ 78 static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos, 79 loff_t count, void *data, struct iomap *iomap, 80 struct iomap *srcmap) 81 { 82 struct iomap_swapfile_info *isi = data; 83 int error; 84 85 switch (iomap->type) { 86 case IOMAP_MAPPED: 87 case IOMAP_UNWRITTEN: 88 /* Only real or unwritten extents. */ 89 break; 90 case IOMAP_INLINE: 91 /* No inline data. */ 92 pr_err("swapon: file is inline\n"); 93 return -EINVAL; 94 default: 95 pr_err("swapon: file has unallocated extents\n"); 96 return -EINVAL; 97 } 98 99 /* No uncommitted metadata or shared blocks. */ 100 if (iomap->flags & IOMAP_F_DIRTY) { 101 pr_err("swapon: file is not committed\n"); 102 return -EINVAL; 103 } 104 if (iomap->flags & IOMAP_F_SHARED) { 105 pr_err("swapon: file has shared extents\n"); 106 return -EINVAL; 107 } 108 109 /* Only one bdev per swap file. */ 110 if (iomap->bdev != isi->sis->bdev) { 111 pr_err("swapon: file is on multiple devices\n"); 112 return -EINVAL; 113 } 114 115 if (isi->iomap.length == 0) { 116 /* No accumulated extent, so just store it. */ 117 memcpy(&isi->iomap, iomap, sizeof(isi->iomap)); 118 } else if (isi->iomap.addr + isi->iomap.length == iomap->addr) { 119 /* Append this to the accumulated extent. */ 120 isi->iomap.length += iomap->length; 121 } else { 122 /* Otherwise, add the retained iomap and store this one. */ 123 error = iomap_swapfile_add_extent(isi); 124 if (error) 125 return error; 126 memcpy(&isi->iomap, iomap, sizeof(isi->iomap)); 127 } 128 return count; 129 } 130 131 /* 132 * Iterate a swap file's iomaps to construct physical extents that can be 133 * passed to the swapfile subsystem. 134 */ 135 int iomap_swapfile_activate(struct swap_info_struct *sis, 136 struct file *swap_file, sector_t *pagespan, 137 const struct iomap_ops *ops) 138 { 139 struct iomap_swapfile_info isi = { 140 .sis = sis, 141 .lowest_ppage = (sector_t)-1ULL, 142 }; 143 struct address_space *mapping = swap_file->f_mapping; 144 struct inode *inode = mapping->host; 145 loff_t pos = 0; 146 loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE); 147 loff_t ret; 148 149 /* 150 * Persist all file mapping metadata so that we won't have any 151 * IOMAP_F_DIRTY iomaps. 152 */ 153 ret = vfs_fsync(swap_file, 1); 154 if (ret) 155 return ret; 156 157 while (len > 0) { 158 ret = iomap_apply(inode, pos, len, IOMAP_REPORT, 159 ops, &isi, iomap_swapfile_activate_actor); 160 if (ret <= 0) 161 return ret; 162 163 pos += ret; 164 len -= ret; 165 } 166 167 if (isi.iomap.length) { 168 ret = iomap_swapfile_add_extent(&isi); 169 if (ret) 170 return ret; 171 } 172 173 /* 174 * If this swapfile doesn't contain even a single page-aligned 175 * contiguous range of blocks, reject this useless swapfile to 176 * prevent confusion later on. 177 */ 178 if (isi.nr_pages == 0) { 179 pr_warn("swapon: Cannot find a single usable page in file.\n"); 180 return -EINVAL; 181 } 182 183 *pagespan = 1 + isi.highest_ppage - isi.lowest_ppage; 184 sis->max = isi.nr_pages; 185 sis->pages = isi.nr_pages - 1; 186 sis->highest_bit = isi.nr_pages - 1; 187 return isi.nr_extents; 188 } 189 EXPORT_SYMBOL_GPL(iomap_swapfile_activate); 190