static u64 extend_obj_stats(struct zram *zram, u16 gid, int type) { if (!CHECK(zram->zgrp, "zram extend is not enable!\n")) return 0; if (!CHECK_BOUND(gid, 0, zram->zgrp->nr_grp - 1)) return 0; if (type == CACHE_SIZE) return atomic64_read(&zram->zgrp->stats[gid].zram_size); else if (type == CACHE_PAGE) return atomic_read(&zram->zgrp->stats[gid].zram_pages); else if (type == CACHE_FAULT) return atomic64_read(&zram->zgrp->stats[gid].zram_fault); #ifdef CONFIG_ZRAM_EXTEND_WRITEBACK else if (type == SWAP_SIZE) return atomic64_read(&zram->zgrp->stats[gid].wb_size); else if (type == SWAP_PAGE) return atomic_read(&zram->zgrp->stats[gid].wb_pages); else if (type == READ_SIZE) return atomic64_read(&zram->zgrp->stats[gid].read_size); else if (type == WRITE_SIZE) return atomic64_read(&zram->zgrp->stats[gid].write_size); else if (type == SWAP_FAULT) return atomic64_read(&zram->zgrp->stats[gid].wb_fault); BUG(); #endif return 0; } 这个函数做一下流程优化

可以做如下的流程优化：

static u64 extend_obj_stats(struct zram *zram, u16 gid, int type) {
    if (!CHECK(zram->zgrp, "zram extend is not enable!\n")) 
        return 0;
    
    if (!CHECK_BOUND(gid, 0, zram->zgrp->nr_grp - 1)) 
        return 0;

    switch (type) {
        case CACHE_SIZE:
            return atomic64_read(&zram->zgrp->stats[gid].zram_size);
        case CACHE_PAGE:
            return atomic_read(&zram->zgrp->stats[gid].zram_pages);
        case CACHE_FAULT:
            return atomic64_read(&zram->zgrp->stats[gid].zram_fault);
#ifdef CONFIG_ZRAM_EXTEND_WRITEBACK
        case SWAP_SIZE:
            return atomic64_read(&zram->zgrp->stats[gid].wb_size);
        case SWAP_PAGE:
            return atomic_read(&zram->zgrp->stats[gid].wb_pages);
        case READ_SIZE:
            return atomic64_read(&zram->zgrp->stats[gid].read_size);
        case WRITE_SIZE:
            return atomic64_read(&zram->zgrp->stats[gid].write_size);
        case SWAP_FAULT:
            return atomic64_read(&zram->zgrp->stats[gid].wb_fault);
#endif
        default:
            break;
    }

    BUG();
    return 0;
}

这里使用 `switch-case` 替换了原来的 `if-else` 结构，使代码更加简洁易读。同时，由于 `BUG()` 表示代码中存在错误，因此可以将其放在 `default` 分支中，避免出现无法预料的错误。