[PATCH v3 4/5] zram: add per-backend caps and validate parameters early

From: Haoqin Huang <[email protected]>

Dict and level parameters are silently accepted even for backends
that do not support them, e.g. "algo=lzo dict=/data/dict" succeeds
but has no effect. Add per-backend caps and zcomp_validate_params()
to reject invalid parameters with a specific error message before
storing. For zstd, set level_max to -1 as a sentinel since its
maximum level is determined at runtime by zstd_max_clevel().

Signed-off-by: Haoqin Huang <[email protected]>
Signed-off-by: Rongwei Wang <[email protected]>
---
 drivers/block/zram/backend_842.c     |  1 +
 drivers/block/zram/backend_deflate.c |  3 +++
 drivers/block/zram/backend_lz4.c     |  3 +++
 drivers/block/zram/backend_lz4hc.c   |  3 +++
 drivers/block/zram/backend_lzo.c     |  1 +
 drivers/block/zram/backend_lzorle.c  |  1 +
 drivers/block/zram/backend_zstd.c    |  3 +++
 drivers/block/zram/zcomp.c           | 27 +++++++++++++++++++++++++++
 drivers/block/zram/zcomp.h           |  7 +++++++
 drivers/block/zram/zram_drv.c        |  7 +++++++
 10 files changed, 56 insertions(+)

diff --git a/drivers/block/zram/backend_842.c b/drivers/block/zram/backend_842.c
index 10d9d5c60f53..d796ebda1fa0 100644
--- a/drivers/block/zram/backend_842.c
+++ b/drivers/block/zram/backend_842.c
@@ -57,5 +57,6 @@ const struct zcomp_ops backend_842 = {
 	.destroy_ctx	= destroy_842,
 	.setup_params	= setup_params_842,
 	.release_params	= release_params_842,
+	.caps		= 0,
 	.name		= "842",
 };
diff --git a/drivers/block/zram/backend_deflate.c b/drivers/block/zram/backend_deflate.c
index f92a52a720d1..cedc3daad33a 100644
--- a/drivers/block/zram/backend_deflate.c
+++ b/drivers/block/zram/backend_deflate.c
@@ -144,5 +144,8 @@ const struct zcomp_ops backend_deflate = {
 	.destroy_ctx	= deflate_destroy,
 	.setup_params	= deflate_setup_params,
 	.release_params	= deflate_release_params,
+	.caps		= ZCOMP_CAP_LEVEL,
+	.level_min	= Z_DEFAULT_COMPRESSION,
+	.level_max	= Z_BEST_COMPRESSION,
 	.name		= "deflate",
 };
diff --git a/drivers/block/zram/backend_lz4.c b/drivers/block/zram/backend_lz4.c
index c449d511ba86..bd1e5ca4d134 100644
--- a/drivers/block/zram/backend_lz4.c
+++ b/drivers/block/zram/backend_lz4.c
@@ -146,5 +146,8 @@ const struct zcomp_ops backend_lz4 = {
 	.destroy_ctx	= lz4_destroy,
 	.setup_params	= lz4_setup_params,
 	.release_params	= lz4_release_params,
+	.caps		= ZCOMP_CAP_DICT | ZCOMP_CAP_LEVEL,
+	.level_min	= LZ4_ACCELERATION_DEFAULT,
+	.level_max	= 65535,
 	.name		= "lz4",
 };
diff --git a/drivers/block/zram/backend_lz4hc.c b/drivers/block/zram/backend_lz4hc.c
index f6a336acfe20..0e0d7c68a7d4 100644
--- a/drivers/block/zram/backend_lz4hc.c
+++ b/drivers/block/zram/backend_lz4hc.c
@@ -124,5 +124,8 @@ const struct zcomp_ops backend_lz4hc = {
 	.destroy_ctx	= lz4hc_destroy,
 	.setup_params	= lz4hc_setup_params,
 	.release_params	= lz4hc_release_params,
+	.caps		= ZCOMP_CAP_DICT | ZCOMP_CAP_LEVEL,
+	.level_min	= LZ4HC_MIN_CLEVEL,
+	.level_max	= LZ4HC_MAX_CLEVEL,
 	.name		= "lz4hc",
 };
diff --git a/drivers/block/zram/backend_lzo.c b/drivers/block/zram/backend_lzo.c
index 4c906beaae6b..965f007e2ca8 100644
--- a/drivers/block/zram/backend_lzo.c
+++ b/drivers/block/zram/backend_lzo.c
@@ -55,5 +55,6 @@ const struct zcomp_ops backend_lzo = {
 	.destroy_ctx	= lzo_destroy,
 	.setup_params	= lzo_setup_params,
 	.release_params	= lzo_release_params,
+	.caps		= 0,
 	.name		= "lzo",
 };
diff --git a/drivers/block/zram/backend_lzorle.c b/drivers/block/zram/backend_lzorle.c
index 10640c96cbfc..757b4598be03 100644
--- a/drivers/block/zram/backend_lzorle.c
+++ b/drivers/block/zram/backend_lzorle.c
@@ -55,5 +55,6 @@ const struct zcomp_ops backend_lzorle = {
 	.destroy_ctx	= lzorle_destroy,
 	.setup_params	= lzorle_setup_params,
 	.release_params	= lzorle_release_params,
+	.caps		= 0,
 	.name		= "lzo-rle",
 };
diff --git a/drivers/block/zram/backend_zstd.c b/drivers/block/zram/backend_zstd.c
index 6febb366f76e..801ee8ee4ba6 100644
--- a/drivers/block/zram/backend_zstd.c
+++ b/drivers/block/zram/backend_zstd.c
@@ -217,5 +217,8 @@ const struct zcomp_ops backend_zstd = {
 	.destroy_ctx	= zstd_destroy,
 	.setup_params	= zstd_setup_params,
 	.release_params	= zstd_release_params,
+	.caps		= ZCOMP_CAP_DICT | ZCOMP_CAP_LEVEL,
+	.level_min	= (int)-ZSTD_TARGETLENGTH_MAX,
+	.level_max	= -1,	/* validated by zstd_setup_params() */
 	.name		= "zstd",
 };
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 974c4691887e..149eff4590e1 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -94,6 +94,33 @@ const char *zcomp_lookup_backend_name(const char *comp)
 	return NULL;
 }
 
+int zcomp_validate_params(const char *comp, s32 level, const char *dict_path)
+{
+	const struct zcomp_ops *backend = lookup_backend_ops(comp);
+
+	if (!backend)
+		return -EINVAL;
+
+	if (dict_path && !(backend->caps & ZCOMP_CAP_DICT)) {
+		pr_err("zram: %s does not support dictionary\n", comp);
+		return -EOPNOTSUPP;
+	}
+
+	if (level != ZCOMP_PARAM_NOT_SET) {
+		if (!(backend->caps & ZCOMP_CAP_LEVEL)) {
+			pr_err("zram: %s does not support level\n", comp);
+			return -EOPNOTSUPP;
+		}
+		/* level_max == -1 means validate in .setup_params() */
+		if (backend->level_max >= 0 &&
+		    (level < backend->level_min || level > backend->level_max)) {
+			pr_err("zram: invalid level %d for %s\n", level, comp);
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
 /* show available compressors */
 ssize_t zcomp_available_show(const char *comp, char *buf, ssize_t at)
 {
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index 81a0f3f6ff48..366250050d4a 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -7,6 +7,9 @@
 
 #define ZCOMP_PARAM_NOT_SET	INT_MIN
 
+#define ZCOMP_CAP_DICT		BIT(0)	/* dictionary support */
+#define ZCOMP_CAP_LEVEL		BIT(1)	/* adjustable compression level */
+
 struct deflate_params {
 	s32 winbits;
 };
@@ -66,6 +69,9 @@ struct zcomp_ops {
 	int (*setup_params)(struct zcomp_params *params);
 	void (*release_params)(struct zcomp_params *params);
 
+	unsigned int caps;
+	s32 level_min;
+	s32 level_max;
 	const char *name;
 };
 
@@ -81,6 +87,7 @@ int zcomp_cpu_up_prepare(unsigned int cpu, struct hlist_node *node);
 int zcomp_cpu_dead(unsigned int cpu, struct hlist_node *node);
 ssize_t zcomp_available_show(const char *comp, char *buf, ssize_t at);
 const char *zcomp_lookup_backend_name(const char *comp);
+int zcomp_validate_params(const char *comp, s32 level, const char *dict_path);
 
 struct zcomp *zcomp_create(const char *alg, struct zcomp_params *params);
 void zcomp_destroy(struct zcomp *comp);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 0223fd83bbba..0c804bb4a701 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1797,6 +1797,13 @@ static ssize_t algorithm_params_store(struct device *dev,
 			return -EINVAL;
 	}
 
+	if (zram->comp_algs[prio]) {
+		ret = zcomp_validate_params(zram->comp_algs[prio], level,
+					    dict_path);
+		if (ret)
+			return ret;
+	}
+
 	ret = comp_params_store(zram, prio, level, dict_path, &deflate_params);
 	return ret ? ret : len;
 }
-- 
2.43.7