[linux-2.6-block.git] / fs / iomap / swapfile.c

// 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;
	uint64_t first_ppage;
	uint64_t first_ppage_reported;
	uint64_t next_ppage;
	int error;

	/*
	 * 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;

	/*
	 * 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_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;
	}

	*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);
Commit	Line	Data
a45c0ecc DW	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
a45c0ecc DW	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	{
81	struct iomap_swapfile_info *isi = data;
82	int error;
83
84	switch (iomap->type) {
85	case IOMAP_MAPPED:
86	case IOMAP_UNWRITTEN:
87	/* Only real or unwritten extents. */
88	break;
89	case IOMAP_INLINE:
90	/* No inline data. */
91	pr_err("swapon: file is inline\n");
92	return -EINVAL;
93	default:
94	pr_err("swapon: file has unallocated extents\n");
95	return -EINVAL;
96	}
97
98	/* No uncommitted metadata or shared blocks. */
99	if (iomap->flags & IOMAP_F_DIRTY) {
100	pr_err("swapon: file is not committed\n");
101	return -EINVAL;
102	}
103	if (iomap->flags & IOMAP_F_SHARED) {
104	pr_err("swapon: file has shared extents\n");
105	return -EINVAL;
106	}
107
108	/* Only one bdev per swap file. */
109	if (iomap->bdev != isi->sis->bdev) {
110	pr_err("swapon: file is on multiple devices\n");
111	return -EINVAL;
112	}
113
114	if (isi->iomap.length == 0) {
115	/* No accumulated extent, so just store it. */
116	memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
117	} else if (isi->iomap.addr + isi->iomap.length == iomap->addr) {
118	/* Append this to the accumulated extent. */
119	isi->iomap.length += iomap->length;
120	} else {
121	/* Otherwise, add the retained iomap and store this one. */
122	error = iomap_swapfile_add_extent(isi);
123	if (error)
124	return error;
125	memcpy(&isi->iomap, iomap, sizeof(isi->iomap));
126	}
127	return count;
128	}
129
130	/*
131	* Iterate a swap file's iomaps to construct physical extents that can be
132	* passed to the swapfile subsystem.
133	*/
134	int iomap_swapfile_activate(struct swap_info_struct *sis,
135	struct file swap_file, sector_t pagespan,
136	const struct iomap_ops *ops)
137	{
138	struct iomap_swapfile_info isi = {
139	.sis = sis,
140	.lowest_ppage = (sector_t)-1ULL,
141	};
142	struct address_space *mapping = swap_file->f_mapping;
143	struct inode *inode = mapping->host;
144	loff_t pos = 0;
145	loff_t len = ALIGN_DOWN(i_size_read(inode), PAGE_SIZE);
146	loff_t ret;
147
148	/*
149	* Persist all file mapping metadata so that we won't have any
150	* IOMAP_F_DIRTY iomaps.
151	*/
152	ret = vfs_fsync(swap_file, 1);
153	if (ret)
154	return ret;
155
156	while (len > 0) {
157	ret = iomap_apply(inode, pos, len, IOMAP_REPORT,
158	ops, &isi, iomap_swapfile_activate_actor);
159	if (ret <= 0)
160	return ret;
161
162	pos += ret;
163	len -= ret;
164	}
165
166	if (isi.iomap.length) {
167	ret = iomap_swapfile_add_extent(&isi);
168	if (ret)
169	return ret;
170	}
171
172	*pagespan = 1 + isi.highest_ppage - isi.lowest_ppage;
173	sis->max = isi.nr_pages;
174	sis->pages = isi.nr_pages - 1;
175	sis->highest_bit = isi.nr_pages - 1;
176	return isi.nr_extents;
177	}
178	EXPORT_SYMBOL_GPL(iomap_swapfile_activate);