// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2018 Oracle. All Rights Reserved.
* Author: Darrick J. Wong <[email protected]>
*/
#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 */
struct file *file;
};
/*
* 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;
}
static int iomap_swapfile_fail(struct iomap_swapfile_info *isi, const char *str)
{
char *buf, *p = ERR_PTR(-ENOMEM);
buf = kmalloc(PATH_MAX, GFP_KERNEL);
if (buf)
p = file_path(isi->file, buf, PATH_MAX);
pr_err("swapon: file %s %s\n", IS_ERR(p) ? "<unknown>" : p, str);
kfree(buf);
return -EINVAL;
}
/*
* 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_iter(const struct iomap_iter *iter,
struct iomap *iomap, struct iomap_swapfile_info *isi)
{
switch (iomap->type) {
case IOMAP_MAPPED:
case IOMAP_UNWRITTEN:
/* Only real or unwritten extents. */
break;
case IOMAP_INLINE:
/* No inline data. */
return iomap_swapfile_fail(isi, "is inline");
default:
return iomap_swapfile_fail(isi, "has unallocated extents");
}
/* No uncommitted metadata or shared blocks. */
if (iomap->flags & IOMAP_F_DIRTY)
return iomap_swapfile_fail(isi, "is not committed");
if (iomap->flags & IOMAP_F_SHARED)
return iomap_swapfile_fail(isi, "has shared extents");
/* Only one bdev per swap file. */
if (iomap->bdev != isi->sis->bdev)
return iomap_swapfile_fail(isi, "outside the main device");
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. */
int error = iomap_swapfile_add_extent(isi);
if (error)
return error;
memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
}
return iomap_length(iter);
}
/*
* 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 inode *inode = swap_file->f_mapping->host;
struct iomap_iter iter = {
.inode = inode,
.pos = 0,
.len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE),
.flags = IOMAP_REPORT,
};
struct iomap_swapfile_info isi = {
.sis = sis,
.lowest_ppage = (sector_t)-1ULL,
.file = swap_file,
};
int 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 ((ret = iomap_iter(&iter, ops)) > 0)
iter.processed = iomap_swapfile_iter(&iter, &iter.iomap, &isi);
if (ret < 0)
return 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);
Codebase Browser
linux