[PATCH 2/6] zram: refactoring flags and writeback stuff

From: Minchan Kim
Date: Fri Nov 16 2018 - 02:20:53 EST

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This patch does renaming some variables and restructuring
some codes for better redability in writeback and zs_free_page.

Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 105 +++++++++++++---------------------
drivers/block/zram/zram_drv.h | 8 +--
2 files changed, 44 insertions(+), 69 deletions(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 472027eaed60..bc59db2b1036 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -55,17 +55,17 @@ static void zram_free_page(struct zram *zram, size_t index);

static int zram_slot_trylock(struct zram *zram, u32 index)
{
- return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].value);
+ return bit_spin_trylock(ZRAM_LOCK, &zram->table[index].flags);
}

static void zram_slot_lock(struct zram *zram, u32 index)
{
- bit_spin_lock(ZRAM_LOCK, &zram->table[index].value);
+ bit_spin_lock(ZRAM_LOCK, &zram->table[index].flags);
}

static void zram_slot_unlock(struct zram *zram, u32 index)
{
- bit_spin_unlock(ZRAM_LOCK, &zram->table[index].value);
+ bit_spin_unlock(ZRAM_LOCK, &zram->table[index].flags);
}

static inline bool init_done(struct zram *zram)
@@ -76,7 +76,7 @@ static inline bool init_done(struct zram *zram)
static inline bool zram_allocated(struct zram *zram, u32 index)
{

- return (zram->table[index].value >> (ZRAM_FLAG_SHIFT + 1)) ||
+ return (zram->table[index].flags >> (ZRAM_FLAG_SHIFT + 1)) ||
zram->table[index].handle;
}

@@ -99,19 +99,19 @@ static void zram_set_handle(struct zram *zram, u32 index, unsigned long handle)
static bool zram_test_flag(struct zram *zram, u32 index,
enum zram_pageflags flag)
{
- return zram->table[index].value & BIT(flag);
+ return zram->table[index].flags & BIT(flag);
}

static void zram_set_flag(struct zram *zram, u32 index,
enum zram_pageflags flag)
{
- zram->table[index].value |= BIT(flag);
+ zram->table[index].flags |= BIT(flag);
}

static void zram_clear_flag(struct zram *zram, u32 index,
enum zram_pageflags flag)
{
- zram->table[index].value &= ~BIT(flag);
+ zram->table[index].flags &= ~BIT(flag);
}

static inline void zram_set_element(struct zram *zram, u32 index,
@@ -127,15 +127,15 @@ static unsigned long zram_get_element(struct zram *zram, u32 index)

static size_t zram_get_obj_size(struct zram *zram, u32 index)
{
- return zram->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1);
+ return zram->table[index].flags & (BIT(ZRAM_FLAG_SHIFT) - 1);
}

static void zram_set_obj_size(struct zram *zram,
u32 index, size_t size)
{
- unsigned long flags = zram->table[index].value >> ZRAM_FLAG_SHIFT;
+ unsigned long flags = zram->table[index].flags >> ZRAM_FLAG_SHIFT;

- zram->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size;
+ zram->table[index].flags = (flags << ZRAM_FLAG_SHIFT) | size;
}

#if PAGE_SIZE != 4096
@@ -282,16 +282,11 @@ static ssize_t mem_used_max_store(struct device *dev,
}

#ifdef CONFIG_ZRAM_WRITEBACK
-static bool zram_wb_enabled(struct zram *zram)
-{
- return zram->backing_dev;
-}
-
static void reset_bdev(struct zram *zram)
{
struct block_device *bdev;

- if (!zram_wb_enabled(zram))
+ if (!zram->backing_dev)
return;

bdev = zram->bdev;
@@ -318,7 +313,7 @@ static ssize_t backing_dev_show(struct device *dev,
ssize_t ret;

down_read(&zram->init_lock);
- if (!zram_wb_enabled(zram)) {
+ if (!zram->backing_dev) {
memcpy(buf, "none\n", 5);
up_read(&zram->init_lock);
return 5;
@@ -446,7 +441,7 @@ static ssize_t backing_dev_store(struct device *dev,
return err;
}

-static unsigned long get_entry_bdev(struct zram *zram)
+static unsigned long alloc_block_bdev(struct zram *zram)
{
unsigned long blk_idx;
unsigned long ret = 0;
@@ -479,13 +474,13 @@ static unsigned long get_entry_bdev(struct zram *zram)
return ret;
}

-static void put_entry_bdev(struct zram *zram, unsigned long entry)
+static void free_block_bdev(struct zram *zram, unsigned long blk_idx)
{
int was_set;
unsigned long flags;

spin_lock_irqsave(&zram->bitmap_lock, flags);
- was_set = test_and_clear_bit(entry, zram->bitmap);
+ was_set = test_and_clear_bit(blk_idx, zram->bitmap);
spin_unlock_irqrestore(&zram->bitmap_lock, flags);
WARN_ON_ONCE(!was_set);
}
@@ -599,7 +594,7 @@ static int write_to_bdev(struct zram *zram, struct bio_vec *bvec,
if (!bio)
return -ENOMEM;

- entry = get_entry_bdev(zram);
+ entry = alloc_block_bdev(zram);
if (!entry) {
bio_put(bio);
return -ENOSPC;
@@ -610,7 +605,7 @@ static int write_to_bdev(struct zram *zram, struct bio_vec *bvec,
if (!bio_add_page(bio, bvec->bv_page, bvec->bv_len,
bvec->bv_offset)) {
bio_put(bio);
- put_entry_bdev(zram, entry);
+ free_block_bdev(zram, entry);
return -EIO;
}

@@ -628,18 +623,7 @@ static int write_to_bdev(struct zram *zram, struct bio_vec *bvec,
return 0;
}

-static void zram_wb_clear(struct zram *zram, u32 index)
-{
- unsigned long entry;
-
- zram_clear_flag(zram, index, ZRAM_WB);
- entry = zram_get_element(zram, index);
- zram_set_element(zram, index, 0);
- put_entry_bdev(zram, entry);
-}
-
#else
-static bool zram_wb_enabled(struct zram *zram) { return false; }
static inline void reset_bdev(struct zram *zram) {};
static int write_to_bdev(struct zram *zram, struct bio_vec *bvec,
u32 index, struct bio *parent,
@@ -654,7 +638,8 @@ static int read_from_bdev(struct zram *zram, struct bio_vec *bvec,
{
return -EIO;
}
-static void zram_wb_clear(struct zram *zram, u32 index) {}
+
+static void free_block_bdev(struct zram *zram, unsigned long blk_idx) {};
#endif

#ifdef CONFIG_ZRAM_MEMORY_TRACKING
@@ -676,11 +661,6 @@ static void zram_accessed(struct zram *zram, u32 index)
zram->table[index].ac_time = ktime_get_boottime();
}

-static void zram_reset_access(struct zram *zram, u32 index)
-{
- zram->table[index].ac_time = 0;
-}
-
static ssize_t read_block_state(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
@@ -761,7 +741,6 @@ static void zram_debugfs_unregister(struct zram *zram)
static void zram_debugfs_create(void) {};
static void zram_debugfs_destroy(void) {};
static void zram_accessed(struct zram *zram, u32 index) {};
-static void zram_reset_access(struct zram *zram, u32 index) {};
static void zram_debugfs_register(struct zram *zram) {};
static void zram_debugfs_unregister(struct zram *zram) {};
#endif
@@ -962,17 +941,18 @@ static void zram_free_page(struct zram *zram, size_t index)
{
unsigned long handle;

- zram_reset_access(zram, index);
-
+#ifdef CONFIG_ZRAM_MEMORY_TRACKING
+ zram->table[index].ac_time = 0;
+#endif
if (zram_test_flag(zram, index, ZRAM_HUGE)) {
zram_clear_flag(zram, index, ZRAM_HUGE);
atomic64_dec(&zram->stats.huge_pages);
}

- if (zram_wb_enabled(zram) && zram_test_flag(zram, index, ZRAM_WB)) {
- zram_wb_clear(zram, index);
- atomic64_dec(&zram->stats.pages_stored);
- return;
+ if (zram_test_flag(zram, index, ZRAM_WB)) {
+ zram_clear_flag(zram, index, ZRAM_WB);
+ free_block_bdev(zram, zram_get_element(zram, index));
+ goto out;
}

/*
@@ -981,10 +961,8 @@ static void zram_free_page(struct zram *zram, size_t index)
*/
if (zram_test_flag(zram, index, ZRAM_SAME)) {
zram_clear_flag(zram, index, ZRAM_SAME);
- zram_set_element(zram, index, 0);
atomic64_dec(&zram->stats.same_pages);
- atomic64_dec(&zram->stats.pages_stored);
- return;
+ goto out;
}

handle = zram_get_handle(zram, index);
@@ -995,10 +973,11 @@ static void zram_free_page(struct zram *zram, size_t index)

atomic64_sub(zram_get_obj_size(zram, index),
&zram->stats.compr_data_size);
+out:
atomic64_dec(&zram->stats.pages_stored);
-
zram_set_handle(zram, index, 0);
zram_set_obj_size(zram, index, 0);
+ WARN_ON_ONCE(zram->table[index].flags & ~(1UL << ZRAM_LOCK));
}

static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
@@ -1009,24 +988,20 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index,
unsigned int size;
void *src, *dst;

- if (zram_wb_enabled(zram)) {
- zram_slot_lock(zram, index);
- if (zram_test_flag(zram, index, ZRAM_WB)) {
- struct bio_vec bvec;
-
- zram_slot_unlock(zram, index);
+ zram_slot_lock(zram, index);
+ if (zram_test_flag(zram, index, ZRAM_WB)) {
+ struct bio_vec bvec;

- bvec.bv_page = page;
- bvec.bv_len = PAGE_SIZE;
- bvec.bv_offset = 0;
- return read_from_bdev(zram, &bvec,
- zram_get_element(zram, index),
- bio, partial_io);
- }
zram_slot_unlock(zram, index);
+
+ bvec.bv_page = page;
+ bvec.bv_len = PAGE_SIZE;
+ bvec.bv_offset = 0;
+ return read_from_bdev(zram, &bvec,
+ zram_get_element(zram, index),
+ bio, partial_io);
}

- zram_slot_lock(zram, index);
handle = zram_get_handle(zram, index);
if (!handle || zram_test_flag(zram, index, ZRAM_SAME)) {
unsigned long value;
@@ -1138,7 +1113,7 @@ static int __zram_bvec_write(struct zram *zram, struct bio_vec *bvec,

if (unlikely(comp_len >= huge_class_size)) {
comp_len = PAGE_SIZE;
- if (zram_wb_enabled(zram) && allow_wb) {
+ if (zram->backing_dev && allow_wb) {
zcomp_stream_put(zram->comp);
ret = write_to_bdev(zram, bvec, index, bio, &element);
if (!ret) {
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 89da501292ff..d75bf190f262 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -30,7 +30,7 @@

/*
- * The lower ZRAM_FLAG_SHIFT bits of table.value is for
+ * The lower ZRAM_FLAG_SHIFT bits of table.flags is for
* object size (excluding header), the higher bits is for
* zram_pageflags.
*
@@ -41,7 +41,7 @@
*/
#define ZRAM_FLAG_SHIFT 24

-/* Flags for zram pages (table[page_no].value) */
+/* Flags for zram pages (table[page_no].flags) */
enum zram_pageflags {
/* zram slot is locked */
ZRAM_LOCK = ZRAM_FLAG_SHIFT,
@@ -60,7 +60,7 @@ struct zram_table_entry {
unsigned long handle;
unsigned long element;
};
- unsigned long value;
+ unsigned long flags;
#ifdef CONFIG_ZRAM_MEMORY_TRACKING
ktime_t ac_time;
#endif
@@ -105,8 +105,8 @@ struct zram {
* zram is claimed so open request will be failed
*/
bool claim; /* Protected by bdev->bd_mutex */
-#ifdef CONFIG_ZRAM_WRITEBACK
struct file *backing_dev;
+#ifdef CONFIG_ZRAM_WRITEBACK
struct block_device *bdev;
unsigned int old_block_size;
unsigned long *bitmap;
--
2.19.1.1215.g8438c0b245-goog

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Next in thread: Minchan Kim: "[PATCH 3/6] zram: introduce ZRAM_IDLE flag"
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