diff options
Diffstat (limited to 'drivers/block/zram')
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 69 | ||||
| -rw-r--r-- | drivers/block/zram/zram_drv.h | 24 |
2 files changed, 60 insertions, 33 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 40743972eaf7..dfa4024c448a 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -183,19 +183,32 @@ static ssize_t comp_algorithm_store(struct device *dev, static int zram_test_flag(struct zram_meta *meta, u32 index, enum zram_pageflags flag) { - return meta->table[index].flags & BIT(flag); + return meta->table[index].value & BIT(flag); } static void zram_set_flag(struct zram_meta *meta, u32 index, enum zram_pageflags flag) { - meta->table[index].flags |= BIT(flag); + meta->table[index].value |= BIT(flag); } static void zram_clear_flag(struct zram_meta *meta, u32 index, enum zram_pageflags flag) { - meta->table[index].flags &= ~BIT(flag); + meta->table[index].value &= ~BIT(flag); +} + +static size_t zram_get_obj_size(struct zram_meta *meta, u32 index) +{ + return meta->table[index].value & (BIT(ZRAM_FLAG_SHIFT) - 1); +} + +static void zram_set_obj_size(struct zram_meta *meta, + u32 index, size_t size) +{ + unsigned long flags = meta->table[index].value >> ZRAM_FLAG_SHIFT; + + meta->table[index].value = (flags << ZRAM_FLAG_SHIFT) | size; } static inline int is_partial_io(struct bio_vec *bvec) @@ -255,7 +268,6 @@ static struct zram_meta *zram_meta_alloc(u64 disksize) goto free_table; } - rwlock_init(&meta->tb_lock); return meta; free_table: @@ -304,7 +316,12 @@ static void handle_zero_page(struct bio_vec *bvec) flush_dcache_page(page); } -/* NOTE: caller should hold meta->tb_lock with write-side */ + +/* + * To protect concurrent access to the same index entry, + * caller should hold this table index entry's bit_spinlock to + * indicate this index entry is accessing. + */ static void zram_free_page(struct zram *zram, size_t index) { struct zram_meta *meta = zram->meta; @@ -324,11 +341,12 @@ static void zram_free_page(struct zram *zram, size_t index) zs_free(meta->mem_pool, handle); - atomic64_sub(meta->table[index].size, &zram->stats.compr_data_size); + atomic64_sub(zram_get_obj_size(meta, index), + &zram->stats.compr_data_size); atomic64_dec(&zram->stats.pages_stored); meta->table[index].handle = 0; - meta->table[index].size = 0; + zram_set_obj_size(meta, index, 0); } static int zram_decompress_page(struct zram *zram, char *mem, u32 index) @@ -339,12 +357,12 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) unsigned long handle; size_t size; - read_lock(&meta->tb_lock); + bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); handle = meta->table[index].handle; - size = meta->table[index].size; + size = zram_get_obj_size(meta, index); if (!handle || zram_test_flag(meta, index, ZRAM_ZERO)) { - read_unlock(&meta->tb_lock); + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); clear_page(mem); return 0; } @@ -355,7 +373,7 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) else ret = zcomp_decompress(zram->comp, cmem, size, mem); zs_unmap_object(meta->mem_pool, handle); - read_unlock(&meta->tb_lock); + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); /* Should NEVER happen. Return bio error if it does. */ if (unlikely(ret)) { @@ -376,14 +394,14 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, struct zram_meta *meta = zram->meta; page = bvec->bv_page; - read_lock(&meta->tb_lock); + bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); if (unlikely(!meta->table[index].handle) || zram_test_flag(meta, index, ZRAM_ZERO)) { - read_unlock(&meta->tb_lock); + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); handle_zero_page(bvec); return 0; } - read_unlock(&meta->tb_lock); + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); if (is_partial_io(bvec)) /* Use a temporary buffer to decompress the page */ @@ -461,10 +479,10 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, if (page_zero_filled(uncmem)) { kunmap_atomic(user_mem); /* Free memory associated with this sector now. */ - write_lock(&zram->meta->tb_lock); + bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); zram_set_flag(meta, index, ZRAM_ZERO); - write_unlock(&zram->meta->tb_lock); + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); atomic64_inc(&zram->stats.zero_pages); ret = 0; @@ -514,12 +532,12 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, * Free memory associated with this sector * before overwriting unused sectors. */ - write_lock(&zram->meta->tb_lock); + bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); meta->table[index].handle = handle; - meta->table[index].size = clen; - write_unlock(&zram->meta->tb_lock); + zram_set_obj_size(meta, index, clen); + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); /* Update stats */ atomic64_add(clen, &zram->stats.compr_data_size); @@ -560,6 +578,7 @@ static void zram_bio_discard(struct zram *zram, u32 index, int offset, struct bio *bio) { size_t n = bio->bi_iter.bi_size; + struct zram_meta *meta = zram->meta; /* * zram manages data in physical block size units. Because logical block @@ -580,13 +599,9 @@ static void zram_bio_discard(struct zram *zram, u32 index, } while (n >= PAGE_SIZE) { - /* - * Discard request can be large so the lock hold times could be - * lengthy. So take the lock once per page. - */ - write_lock(&zram->meta->tb_lock); + bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); - write_unlock(&zram->meta->tb_lock); + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); index++; n -= PAGE_SIZE; } @@ -821,9 +836,9 @@ static void zram_slot_free_notify(struct block_device *bdev, zram = bdev->bd_disk->private_data; meta = zram->meta; - write_lock(&meta->tb_lock); + bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value); zram_free_page(zram, index); - write_unlock(&meta->tb_lock); + bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value); atomic64_inc(&zram->stats.notify_free); } diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index c8161bd8969c..5b0afde729cd 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -50,10 +50,24 @@ static const size_t max_zpage_size = PAGE_SIZE / 4 * 3; #define ZRAM_SECTOR_PER_LOGICAL_BLOCK \ (1 << (ZRAM_LOGICAL_BLOCK_SHIFT - SECTOR_SHIFT)) -/* Flags for zram pages (table[page_no].flags) */ + +/* + * The lower ZRAM_FLAG_SHIFT bits of table.value is for + * object size (excluding header), the higher bits is for + * zram_pageflags. + * + * zram is mainly used for memory efficiency so we want to keep memory + * footprint small so we can squeeze size and flags into a field. + * The lower ZRAM_FLAG_SHIFT bits is for object size (excluding header), + * the higher bits is for zram_pageflags. + */ +#define ZRAM_FLAG_SHIFT 24 + +/* Flags for zram pages (table[page_no].value) */ enum zram_pageflags { /* Page consists entirely of zeros */ - ZRAM_ZERO, + ZRAM_ZERO = ZRAM_FLAG_SHIFT + 1, + ZRAM_ACCESS, /* page in now accessed */ __NR_ZRAM_PAGEFLAGS, }; @@ -63,9 +77,8 @@ enum zram_pageflags { /* Allocated for each disk page */ struct zram_table_entry { unsigned long handle; - u16 size; /* object size (excluding header) */ - u8 flags; -} __aligned(4); + unsigned long value; +}; struct zram_stats { atomic64_t compr_data_size; /* compressed size of pages stored */ @@ -80,7 +93,6 @@ struct zram_stats { }; struct zram_meta { - rwlock_t tb_lock; /* protect table */ struct zram_table_entry *table; struct zs_pool *mem_pool; }; |