Revert "block: zram: Add support for dynamic compressor switch"submit/tizen/20200825.023546accepted/tizen/unified/20200825.142845

Since dynamic compress switch increases memory usage of meta data along
with the size of zram, in order to saving memory, this reverts commit
'2aab8469d74f ("block: zram Add support for dynamic compressor switch")'

Change-Id: Idd6e1f6f938ca2ebb24ba3e8c65a838bf8fc84d4
Signed-off-by: Dongwoo Lee <dwoo08.lee@samsung.com>

4 files changed, 48 insertions, 98 deletions

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index a02f08daf87a..1a8564a79d8d 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -63,6 +63,24 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp)
 	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)
 {
@@ -184,43 +202,29 @@ cleanup:
 	return ret;
 }
 
-static void zcomp_destroy(struct zcomp *comp)
+void zcomp_destroy(struct zcomp *comp)
 {
 	cpuhp_state_remove_instance(CPUHP_ZCOMP_PREPARE, &comp->node);
 	free_percpu(comp->stream);
 	kfree(comp);
 }
 
-void zcomp_reset(struct list_head *blist)
-{
-	struct list_head *curr, *next;
-	struct zcomp *comp;
-	int i;
-
-	list_for_each_safe(curr, next, blist) {
-		comp = list_entry(curr, struct zcomp, list);
-		list_del(&comp->list);
-
-		i = __sysfs_match_string(backends, -1, comp->name);
-		if (i < 0)
-			kfree(comp->name);
-
-		zcomp_destroy(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().
  */
-static struct zcomp *zcomp_create(const char *compress)
+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);
@@ -233,43 +237,3 @@ static struct zcomp *zcomp_create(const char *compress)
 	}
 	return comp;
 }
-
-struct zcomp *zcomp_get_instance(struct list_head *blist, const char *name)
-{
-	struct zcomp *comp;
-	const char *comp_name = NULL;
-	int i;
-
-	list_for_each_entry(comp, blist, list)
-		if (sysfs_streq(name, comp->name))
-			return comp;
-
-	i = __sysfs_match_string(backends, -1, name);
-	if (i >= 0)
-		comp_name = backends[i];
-	else {
-		/*
-		 * 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.
-		 */
-		if (crypto_has_comp(name, 0, 0) == 1)
-			comp_name = kstrdup(name, GFP_KERNEL);
-		else
-			return ERR_PTR(-ENOENT);
-	}
-
-	comp = zcomp_create(comp_name);
-	if (IS_ERR(comp)) {
-		pr_err("Cannot initialise %s compressing backend\n", name);
-		if (i < 0)
-			kfree(comp_name);
-		return comp;
-	}
-
-	list_add(&comp->list, blist);
-
-	return comp;
-}
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
index aff688d16245..1806475b919d 100644
--- a/drivers/block/zram/zcomp.h
+++ b/drivers/block/zram/zcomp.h
@@ -17,15 +17,15 @@ struct zcomp {
 	struct zcomp_strm * __percpu *stream;
 	const char *name;
 	struct hlist_node node;
-	struct list_head list;
 };
 
 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);
+bool zcomp_available_algorithm(const char *comp);
 
-struct zcomp *zcomp_get_instance(struct list_head *blist, const char *name);
-void zcomp_reset(struct list_head *blist);
+struct zcomp *zcomp_create(const char *comp);
+void zcomp_destroy(struct zcomp *comp);
 
 struct zcomp_strm *zcomp_stream_get(struct zcomp *comp);
 void zcomp_stream_put(struct zcomp *comp);
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 6335e660d22a..1bf4a908a0bd 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -121,17 +121,6 @@ static unsigned long zram_get_element(struct zram *zram, u32 index)
 	return zram->table[index].element;
 }
 
-static inline void zram_set_compressor(struct zram *zram, u32 index,
-			struct zcomp *comp)
-{
-	zram->table[index].compressor = comp;
-}
-
-static struct zcomp *zram_get_compressor(struct zram *zram, u32 index)
-{
-	return zram->table[index].compressor;
-}
-
 static size_t zram_get_obj_size(struct zram *zram, u32 index)
 {
 	return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
@@ -996,7 +985,6 @@ static ssize_t comp_algorithm_store(struct device *dev,
 		struct device_attribute *attr, const char *buf, size_t len)
 {
 	struct zram *zram = dev_to_zram(dev);
-	struct zcomp *comp;
 	char compressor[ARRAY_SIZE(zram->compressor)];
 	size_t sz;
 
@@ -1006,12 +994,16 @@ static ssize_t comp_algorithm_store(struct device *dev,
 	if (sz > 0 && compressor[sz - 1] == '\n')
 		compressor[sz - 1] = 0x00;
 
-	comp = zcomp_get_instance(&zram->backend_list, compressor);
-	if (IS_ERR_OR_NULL(comp))
+	if (!zcomp_available_algorithm(compressor))
 		return -EINVAL;
 
 	down_write(&zram->init_lock);
-	zram->comp = comp;
+	if (init_done(zram)) {
+		up_write(&zram->init_lock);
+		pr_info("Can't change algorithm for initialized device\n");
+		return -EBUSY;
+	}
+
 	strcpy(zram->compressor, compressor);
 	up_write(&zram->init_lock);
 	return len;
@@ -1206,7 +1198,6 @@ static void zram_free_page(struct zram *zram, size_t index)
 		return;
 
 	zs_free(zram->mem_pool, handle);
-	zram->table[index].compressor = NULL;
 
 	atomic64_sub(zram_get_obj_size(zram, index),
 			&zram->stats.compr_data_size);
@@ -1262,13 +1253,12 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
 		kunmap_atomic(dst);
 		ret = 0;
 	} else {
-		struct zcomp *comp = zram_get_compressor(zram, index);
-		struct zcomp_strm *zstrm = zcomp_stream_get(comp);
+		struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp);
 
 		dst = kmap_atomic(page);
 		ret = zcomp_decompress(zstrm, src, size, dst);
 		kunmap_atomic(dst);
-		zcomp_stream_put(comp);
+		zcomp_stream_put(zram->comp);
 	}
 	zs_unmap_object(zram->mem_pool, handle);
 	zram_slot_unlock(zram, index);
@@ -1322,7 +1312,6 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 	unsigned int comp_len = 0;
 	void *src, *dst, *mem;
 	struct zcomp_strm *zstrm;
-	struct zcomp *comp = NULL;
 	struct page *page = bvec->bv_page;
 	unsigned long element = 0;
 	enum zram_pageflags flags = 0;
@@ -1338,14 +1327,13 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,
 	kunmap_atomic(mem);
 
 compress_again:
-	comp = zram->comp;
-	zstrm = zcomp_stream_get(comp);
+	zstrm = zcomp_stream_get(zram->comp);
 	src = kmap_atomic(page);
 	ret = zcomp_compress(zstrm, src, &comp_len);
 	kunmap_atomic(src);
 
 	if (unlikely(ret)) {
-		zcomp_stream_put(comp);
+		zcomp_stream_put(zram->comp);
 		pr_err("Compression failed! err=%d\n", ret);
 		zs_free(zram->mem_pool, handle);
 		return ret;
@@ -1373,7 +1361,7 @@ compress_again:
 				__GFP_HIGHMEM |
 				__GFP_MOVABLE);
 	if (!handle) {
-		zcomp_stream_put(comp);
+		zcomp_stream_put(zram->comp);
 		atomic64_inc(&zram->stats.writestall);
 		handle = zs_malloc(zram->mem_pool, comp_len,
 				GFP_NOIO | __GFP_HIGHMEM |
@@ -1387,7 +1375,7 @@ compress_again:
 	update_used_max(zram, alloced_pages);
 
 	if (zram->limit_pages && alloced_pages > zram->limit_pages) {
-		zcomp_stream_put(comp);
+		zcomp_stream_put(zram->comp);
 		zs_free(zram->mem_pool, handle);
 		return -ENOMEM;
 	}
@@ -1401,7 +1389,7 @@ compress_again:
 	if (comp_len == PAGE_SIZE)
 		kunmap_atomic(src);
 
-	zcomp_stream_put(comp);
+	zcomp_stream_put(zram->comp);
 	zs_unmap_object(zram->mem_pool, handle);
 	atomic64_add(comp_len, &zram->stats.compr_data_size);
 out:
@@ -1423,8 +1411,6 @@ out:
 	}  else {
 		zram_set_handle(zram, index, handle);
 		zram_set_obj_size(zram, index, comp_len);
-		if (comp_len < PAGE_SIZE)
-			zram_set_compressor(zram, index, comp);
 	}
 	zram_slot_unlock(zram, index);
 
@@ -1689,6 +1675,7 @@ out:
 
 static void zram_reset_device(struct zram *zram)
 {
+	struct zcomp *comp;
 	u64 disksize;
 
 	down_write(&zram->init_lock);
@@ -1700,6 +1687,7 @@ static void zram_reset_device(struct zram *zram)
 		return;
 	}
 
+	comp = zram->comp;
 	disksize = zram->disksize;
 	zram->disksize = 0;
 
@@ -1710,8 +1698,7 @@ static void zram_reset_device(struct zram *zram)
 	/* I/O operation under all of CPU are done so let's free */
 	zram_meta_free(zram, disksize);
 	memset(&zram->stats, 0, sizeof(zram->stats));
-	zram->comp = NULL;
-	zcomp_reset(&zram->backend_list);
+	zcomp_destroy(comp);
 	reset_bdev(zram);
 }
 
@@ -1740,8 +1727,10 @@ static ssize_t disksize_store(struct device *dev,
 		goto out_unlock;
 	}
 
-	comp = zcomp_get_instance(&zram->backend_list, zram->compressor);
-	if (IS_ERR_OR_NULL(comp)) {
+	comp = zcomp_create(zram->compressor);
+	if (IS_ERR(comp)) {
+		pr_err("Cannot initialise %s compressing backend\n",
+				zram->compressor);
 		err = PTR_ERR(comp);
 		goto out_free_meta;
 	}
@@ -1964,7 +1953,6 @@ static int zram_add(void)
 	device_add_disk(NULL, zram->disk, zram_disk_attr_groups);
 
 	strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor));
-	INIT_LIST_HEAD(&zram->backend_list);
 
 	zram_debugfs_register(zram);
 	pr_info("Added device: %s\n", zram->disk->disk_name);
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 83b320fb5d6c..f2fd46daa760 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -63,7 +63,6 @@ struct zram_table_entry {
 		unsigned long element;
 	};
 	unsigned long flags;
-	struct zcomp *compressor;
 #ifdef CONFIG_ZRAM_MEMORY_TRACKING
 	ktime_t ac_time;
 #endif
@@ -113,7 +112,6 @@ struct zram {
 	 * zram is claimed so open request will be failed
 	 */
 	bool claim; /* Protected by bdev->bd_mutex */
-	struct list_head backend_list;
 	struct file *backing_dev;
 #ifdef CONFIG_ZRAM_WRITEBACK
 	spinlock_t wb_limit_lock;