zram: refactor flags and writeback stuff

Rename some variables and restructure some code for better readability in
writeback and zs_free_page.

Link: http://lkml.kernel.org/r/20181127055429.251614-4-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Joey Pabalinas <joeypabalinas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index d1459cc..4457d03 100644 (file)
--- 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;
@@ -447,7 +442,7 @@ out:
        return err;
 }
 
-static unsigned long get_entry_bdev(struct zram *zram)
+static unsigned long alloc_block_bdev(struct zram *zram)
 {
        unsigned long blk_idx = 1;
 retry:
@@ -462,11 +457,11 @@ retry:
        return blk_idx;
 }
 
-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;
 
-       was_set = test_and_clear_bit(entry, zram->bitmap);
+       was_set = test_and_clear_bit(blk_idx, zram->bitmap);
        WARN_ON_ONCE(!was_set);
 }
 
@@ -579,7 +574,7 @@ 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;
@@ -590,7 +585,7 @@ 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;
        }
 
@@ -608,18 +603,7 @@ 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,
@@ -634,7 +618,8 @@ 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
@@ -656,11 +641,6 @@ 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)
 {
@@ -741,7 +721,6 @@ 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
@@ -942,17 +921,18 @@ 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;
        }
 
        /*
@@ -961,10 +941,8 @@ 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);
@@ -975,10 +953,11 @@ 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,
@@ -989,24 +968,20 @@ 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;
@@ -1118,7 +1093,7 @@ compress_again:
 
        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 d1095df..4f83f1f 100644 (file)
--- 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;