Release 4.11 drivers/block/zram/zcomp.c

/*
 * Copyright (C) 2014 Sergey Senozhatsky.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/cpu.h>
#include <linux/crypto.h>

#include "zcomp.h"


static const char * const backends[] = {
	"lzo",
#if IS_ENABLED(CONFIG_CRYPTO_LZ4)
	"lz4",
#endif
#if IS_ENABLED(CONFIG_CRYPTO_DEFLATE)
	"deflate",
#endif
#if IS_ENABLED(CONFIG_CRYPTO_LZ4HC)
	"lz4hc",
#endif
#if IS_ENABLED(CONFIG_CRYPTO_842)
	"842",
#endif
	NULL
};



static void zcomp_strm_free(struct zcomp_strm *zstrm)
{
	if (!IS_ERR_OR_NULL(zstrm->tfm))
		crypto_free_comp(zstrm->tfm);
	free_pages((unsigned long)zstrm->buffer, 1);
	kfree(zstrm);
}

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/*
 * allocate new zcomp_strm structure with ->tfm initialized by
 * backend, return NULL on error
 */


static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
{
	struct zcomp_strm *zstrm = kmalloc(sizeof(*zstrm), GFP_KERNEL);
	if (!zstrm)
		return NULL;

	zstrm->tfm = crypto_alloc_comp(comp->name, 0, 0);
	/*
         * allocate 2 pages. 1 for compressed data, plus 1 extra for the
         * case when compressed size is larger than the original one
         */
	zstrm->buffer = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, 1);
	if (IS_ERR_OR_NULL(zstrm->tfm) || !zstrm->buffer) {
		zcomp_strm_free(zstrm);
		zstrm = NULL;
	}
	return zstrm;
}

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98
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bool zcomp_available_algorithm(const char *comp)
{
	int i = 0;

	while (backends[i]) {
		if (sysfs_streq(comp, backends[i]))
			return true;
		i++;
	}

	/*
         * Crypto does not ignore a trailing new line symbol,
         * so make sure you don't supply a string containing
         * one.
         * This also means that we permit zcomp initialisation
         * with any compressing algorithm known to crypto api.
         */
	return crypto_has_comp(comp, 0, 0) == 1;
}

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/* show available compressors */


ssize_t zcomp_available_show(const char *comp, char *buf)
{
	bool known_algorithm = false;
	ssize_t sz = 0;
	int i = 0;

	for (; backends[i]; i++) {
		if (!strcmp(comp, backends[i])) {
			known_algorithm = true;
			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
					"[%s] ", backends[i]);
		} else {
			sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
					"%s ", backends[i]);
		}
	}

	/*
         * Out-of-tree module known to crypto api or a missing
         * entry in `backends'.
         */
	if (!known_algorithm && crypto_has_comp(comp, 0, 0) == 1)
		sz += scnprintf(buf + sz, PAGE_SIZE - sz - 2,
				"[%s] ", comp);

	sz += scnprintf(buf + sz, PAGE_SIZE - sz, "\n");
	return sz;
}

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1
0.62%
1
25.00%
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162
100.00%
4
100.00%



struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
{
	return *get_cpu_ptr(comp->stream);
}

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void zcomp_stream_put(struct zcomp *comp)
{
	put_cpu_ptr(comp->stream);
}

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int zcomp_compress(struct zcomp_strm *zstrm,
		const void *src, unsigned int *dst_len)
{
	/*
         * Our dst memory (zstrm->buffer) is always `2 * PAGE_SIZE' sized
         * because sometimes we can endup having a bigger compressed data
         * due to various reasons: for example compression algorithms tend
         * to add some padding to the compressed buffer. Speaking of padding,
         * comp algorithm `842' pads the compressed length to multiple of 8
         * and returns -ENOSP when the dst memory is not big enough, which
         * is not something that ZRAM wants to see. We can handle the
         * `compressed_size > PAGE_SIZE' case easily in ZRAM, but when we
         * receive -ERRNO from the compressing backend we can't help it
         * anymore. To make `842' happy we need to tell the exact size of
         * the dst buffer, zram_drv will take care of the fact that
         * compressed buffer is too big.
         */
	*dst_len = PAGE_SIZE * 2;

	return crypto_comp_compress(zstrm->tfm,
			src, PAGE_SIZE,
			zstrm->buffer, dst_len);
}

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int zcomp_decompress(struct zcomp_strm *zstrm,
		const void *src, unsigned int src_len, void *dst)
{
	unsigned int dst_len = PAGE_SIZE;

	return crypto_comp_decompress(zstrm->tfm,
			src, src_len,
			dst, &dst_len);
}

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int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node)
{
	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
	struct zcomp_strm *zstrm;

	if (WARN_ON(*per_cpu_ptr(comp->stream, cpu)))
		return 0;

	zstrm = zcomp_strm_alloc(comp);
	if (IS_ERR_OR_NULL(zstrm)) {
		pr_err("Can't allocate a compression stream\n");
		return -ENOMEM;
	}
	*per_cpu_ptr(comp->stream, cpu) = zstrm;
	return 0;
}

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33.70%
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100.00%
5
100.00%



int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node)
{
	struct zcomp *comp = hlist_entry(node, struct zcomp, node);
	struct zcomp_strm *zstrm;

	zstrm = *per_cpu_ptr(comp->stream, cpu);
	if (!IS_ERR_OR_NULL(zstrm))
		zcomp_strm_free(zstrm);
	*per_cpu_ptr(comp->stream, cpu) = NULL;
	return 0;
}

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45.95%
1
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4
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static int zcomp_init(struct zcomp *comp)
{
	int ret;

	comp->stream = alloc_percpu(struct zcomp_strm *);
	if (!comp->stream)
		return -ENOMEM;

	ret = cpuhp_state_add_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
	if (ret < 0)
		goto cleanup;
	return 0;

cleanup:
	free_percpu(comp->stream);
	return ret;
}

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void zcomp_destroy(struct zcomp *comp)
{
	cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
	free_percpu(comp->stream);
	kfree(comp);
}

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1
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/*
 * search available compressors for requested algorithm.
 * allocate new zcomp and initialize it. return compressing
 * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL)
 * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in
 * case of allocation error, or any other error potentially
 * returned by zcomp_init().
 */


struct zcomp *zcomp_create(const char *compress)
{
	struct zcomp *comp;
	int error;

	if (!zcomp_available_algorithm(compress))
		return ERR_PTR(-EINVAL);

	comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
	if (!comp)
		return ERR_PTR(-ENOMEM);

	comp->name = compress;
	error = zcomp_init(comp);
	if (error) {
		kfree(comp);
		return ERR_PTR(error);
	}
	return comp;
}
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86
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87.50%
Luis Henriques
7
7.53%
1
12.50%
Total
93
100.00%
8
100.00%

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850
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82.35%
Anna-Maria Gleixner
80
8.52%
1
5.88%
Luis Henriques
7
0.75%
1
5.88%
MinChan Kim
2
0.21%
1
5.88%
Total
939
100.00%
17
100.00%
Directory: drivers/block/zram

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