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-rw-r--r--drivers/block/zram/zcomp.c242
1 files changed, 242 insertions, 0 deletions
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
new file mode 100644
index 000000000..4ed0a78fd
--- /dev/null
+++ b/drivers/block/zram/zcomp.c
@@ -0,0 +1,242 @@
+/*
+ * 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_LZ4HC)
+ "lz4hc",
+#endif
+#if IS_ENABLED(CONFIG_CRYPTO_842)
+ "842",
+#endif
+#if IS_ENABLED(CONFIG_CRYPTO_ZSTD)
+ "zstd",
+#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);
+}
+
+/*
+ * 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;
+}
+
+bool zcomp_available_algorithm(const char *comp)
+{
+ int i;
+
+ i = __sysfs_match_string(backends, -1, comp);
+ if (i >= 0)
+ return true;
+
+ /*
+ * 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;
+}
+
+/* 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;
+}
+
+struct zcomp_strm *zcomp_stream_get(struct zcomp *comp)
+{
+ return *get_cpu_ptr(comp->stream);
+}
+
+void zcomp_stream_put(struct zcomp *comp)
+{
+ put_cpu_ptr(comp->stream);
+}
+
+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);
+}
+
+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);
+}
+
+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;
+}
+
+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;
+}
+
+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;
+}
+
+void zcomp_destroy(struct zcomp *comp)
+{
+ cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
+ free_percpu(comp->stream);
+ kfree(comp);
+}
+
+/*
+ * 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;
+}