// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2018 Oracle. All Rights Reserved.
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* Author: Darrick J. Wong <darrick.wong@oracle.com>
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*/
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#include <linux/module.h>
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/iomap.h>
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#include <linux/swap.h>
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/* Swapfile activation */
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struct iomap_swapfile_info {
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struct iomap iomap; /* accumulated iomap */
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struct swap_info_struct *sis;
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uint64_t lowest_ppage; /* lowest physical addr seen (pages) */
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uint64_t highest_ppage; /* highest physical addr seen (pages) */
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unsigned long nr_pages; /* number of pages collected */
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int nr_extents; /* extent count */
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};
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/*
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* Collect physical extents for this swap file. Physical extents reported to
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* the swap code must be trimmed to align to a page boundary. The logical
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* offset within the file is irrelevant since the swapfile code maps logical
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* page numbers of the swap device to the physical page-aligned extents.
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*/
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static int iomap_swapfile_add_extent(struct iomap_swapfile_info *isi)
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{
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struct iomap *iomap = &isi->iomap;
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unsigned long nr_pages;
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unsigned long max_pages;
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uint64_t first_ppage;
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uint64_t first_ppage_reported;
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uint64_t next_ppage;
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int error;
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if (unlikely(isi->nr_pages >= isi->sis->max))
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return 0;
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max_pages = isi->sis->max - isi->nr_pages;
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/*
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* Round the start up and the end down so that the physical
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* extent aligns to a page boundary.
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*/
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first_ppage = ALIGN(iomap->addr, PAGE_SIZE) >> PAGE_SHIFT;
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next_ppage = ALIGN_DOWN(iomap->addr + iomap->length, PAGE_SIZE) >>
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PAGE_SHIFT;
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/* Skip too-short physical extents. */
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if (first_ppage >= next_ppage)
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return 0;
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nr_pages = next_ppage - first_ppage;
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nr_pages = min(nr_pages, max_pages);
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/*
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* Calculate how much swap space we're adding; the first page contains
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* the swap header and doesn't count. The mm still wants that first
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* page fed to add_swap_extent, however.
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*/
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first_ppage_reported = first_ppage;
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if (iomap->offset == 0)
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first_ppage_reported++;
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if (isi->lowest_ppage > first_ppage_reported)
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isi->lowest_ppage = first_ppage_reported;
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if (isi->highest_ppage < (next_ppage - 1))
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isi->highest_ppage = next_ppage - 1;
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/* Add extent, set up for the next call. */
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error = add_swap_extent(isi->sis, isi->nr_pages, nr_pages, first_ppage);
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if (error < 0)
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return error;
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isi->nr_extents += error;
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isi->nr_pages += nr_pages;
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return 0;
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}
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/*
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* Accumulate iomaps for this swap file. We have to accumulate iomaps because
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* swap only cares about contiguous page-aligned physical extents and makes no
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* distinction between written and unwritten extents.
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*/
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static loff_t iomap_swapfile_activate_actor(struct inode *inode, loff_t pos,
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loff_t count, void *data, struct iomap *iomap,
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struct iomap *srcmap)
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{
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struct iomap_swapfile_info *isi = data;
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int error;
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switch (iomap->type) {
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case IOMAP_MAPPED:
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case IOMAP_UNWRITTEN:
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/* Only real or unwritten extents. */
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break;
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case IOMAP_INLINE:
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/* No inline data. */
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pr_err("swapon: file is inline\n");
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return -EINVAL;
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default:
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pr_err("swapon: file has unallocated extents\n");
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return -EINVAL;
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}
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/* No uncommitted metadata or shared blocks. */
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if (iomap->flags & IOMAP_F_DIRTY) {
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pr_err("swapon: file is not committed\n");
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return -EINVAL;
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}
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if (iomap->flags & IOMAP_F_SHARED) {
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pr_err("swapon: file has shared extents\n");
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return -EINVAL;
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}
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/* Only one bdev per swap file. */
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if (iomap->bdev != isi->sis->bdev) {
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pr_err("swapon: file is on multiple devices\n");
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return -EINVAL;
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}
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if (isi->iomap.length == 0) {
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/* No accumulated extent, so just store it. */
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memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
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} else if (isi->iomap.addr + isi->iomap.length == iomap->addr) {
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/* Append this to the accumulated extent. */
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isi->iomap.length += iomap->length;
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} else {
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/* Otherwise, add the retained iomap and store this one. */
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error = iomap_swapfile_add_extent(isi);
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if (error)
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return error;
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memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
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}
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return count;
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}
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/*
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* Iterate a swap file's iomaps to construct physical extents that can be
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* passed to the swapfile subsystem.
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*/
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int iomap_swapfile_activate(struct swap_info_struct *sis,
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struct file *swap_file, sector_t *pagespan,
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const struct iomap_ops *ops)
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{
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struct iomap_swapfile_info isi = {
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.sis = sis,
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.lowest_ppage = (sector_t)-1ULL,
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};
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struct address_space *mapping = swap_file->f_mapping;
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struct inode *inode = mapping->host;
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loff_t pos = 0;
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loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE);
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loff_t ret;
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/*
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* Persist all file mapping metadata so that we won't have any
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* IOMAP_F_DIRTY iomaps.
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*/
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ret = vfs_fsync(swap_file, 1);
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if (ret)
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return ret;
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while (len > 0) {
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ret = iomap_apply(inode, pos, len, IOMAP_REPORT,
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ops, &isi, iomap_swapfile_activate_actor);
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if (ret <= 0)
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return ret;
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pos += ret;
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len -= ret;
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}
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if (isi.iomap.length) {
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ret = iomap_swapfile_add_extent(&isi);
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if (ret)
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return ret;
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}
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/*
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* If this swapfile doesn't contain even a single page-aligned
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* contiguous range of blocks, reject this useless swapfile to
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* prevent confusion later on.
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*/
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if (isi.nr_pages == 0) {
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pr_warn("swapon: Cannot find a single usable page in file.\n");
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return -EINVAL;
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}
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*pagespan = 1 + isi.highest_ppage - isi.lowest_ppage;
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sis->max = isi.nr_pages;
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sis->pages = isi.nr_pages - 1;
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sis->highest_bit = isi.nr_pages - 1;
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return isi.nr_extents;
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}
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EXPORT_SYMBOL_GPL(iomap_swapfile_activate);
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