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