From nobody Thu Oct 9 08:54:07 2025 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 858BB274FC2 for ; Wed, 18 Jun 2025 13:26:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750253193; cv=none; b=i303ld1OqdzgXKU7tqn5aAZgAYtmOZE4BxUXOzKnA3zRlLBxT94tBFh17SURL7LexZXhYx/vHJzA5WwPtKr9a4+AWemIFmdDi+SRRnH9TBiBrCU11Cm9Xpu0ESi0a4+8fGxF/SmdT4qnLAtxJLLhjSnMV7Xu6oo+xMeQ3u0Oi5o= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750253193; c=relaxed/simple; bh=bYrHSQVYNOUayEsJLSoaaBxt1LOaJZAAWeKboOTC6bo=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=Ikz4dqhV1KgqUkp3sdfzAjOO4BPsJlZhj2Fkt3bxStV431c+O0IkdbO+GfPtX8Syi822xVIgcKdJLVR0EKtrEXOvv5lvzCZjES4eH9QDVq+mJS2z6NoIO6ayfF8hmLvlv7ZqmgylqlDyrb27CHfynXh0Uhjcg9to5sByHZrhA54= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--richardycc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=gyZqYVDI; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--richardycc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="gyZqYVDI" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-234dbbc4899so104838125ad.2 for ; Wed, 18 Jun 2025 06:26:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1750253191; x=1750857991; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=W7GJ0CAsHPIqX2Owo4ue8T4Rk2EdRyqQpbzciyT4MnQ=; b=gyZqYVDI8Me000aaCp+GRlcpS7djYSStNdXAMJx0qC44IyhG1KQPYAWcMRpxVikybg Pq5F/vhxpZ+6svN1yLmxx0dchubzwHn0XCzcYA8SimyfEk5HWAFkBlXmeIXzlvUnFE4y sHj/NSDw/Q5cT0FTLkGl2183RiHILyNGMiA31vYv8w1MhTzdozYqLqO5gnPjEsjc2tku V6bSzupdIMkxXnPwPIImZpOpPDu7VVL09ZYHN0g6uYxYFPmxSbo4MYCNZrxjVSGUiPB4 DPMRpJvC2gr7Rpi15/wFqw/DBI5Z/UHYCJNqbl0K6NsXDfGH1zWURMOJNrEeubAWHFPu K8gQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750253191; x=1750857991; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=W7GJ0CAsHPIqX2Owo4ue8T4Rk2EdRyqQpbzciyT4MnQ=; b=q4Gle0jvdkxXer29zsnUfqZyMoa9z/pBKrKFpMl7Dgud1G6ctDaKHXrQio+g3BNga2 SDXaR4qNMV0c4oghql/QXYs035SbQbsbbWvQbwWhpTyqoG66PLRKH4anDQY3oEjHYqAJ RHMs1dx7evoVOZkMm2aTPAjka8HrEK50sEsmlg2c84g4r14tC0RicLZbsgjFxKHB+pdC iM1BvfxV8Ad19RD9fub1YOriXo5sBTiGBtXKTZMntJ0QiU+LR58gXD5tI7AL/3FCAtG8 Rlhu2ZSoOQ6Mv2wZ9Md4F+UDrxH5SYF8x4+NZsRvd7x4bDEcq+iqtWUVnN8TgvWoaAhC sPVw== X-Forwarded-Encrypted: i=1; AJvYcCUKCEB9AbuMKn8vN0Uu/s7yDjv6wvkTo7VX5LvF1PQc0wMhXdkkYO9baRowbvhDk9edX5lfZzEMkBOAzwY=@vger.kernel.org X-Gm-Message-State: AOJu0Ywo2yI+Q/XUFs7+wowopbQImEgqGHRuzGZWywww2MMbWGfOHtAp dcWdMp8zXXvi6Y0drTUXUs0wqLtPueFNg8GGa4Um+/X4umUbYbyeQmRB1qU35Nw7ib6uW2zCggp I0rv/PqK96gbzJZOCpcYM X-Google-Smtp-Source: AGHT+IEMboGn3F8NlMbfTFMekCEuRM6W/hQZqKmJzSmEZMuOhl9cMu8YBKUPk2+WBPekkrBULauJt3S7ZAY9MgVG X-Received: from pjtd4.prod.google.com ([2002:a17:90b:44:b0:311:a4ee:7c3d]) (user=richardycc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:760f:b0:236:6f5f:cac1 with SMTP id d9443c01a7336-2366f5fcea1mr169653105ad.46.1750253190946; Wed, 18 Jun 2025 06:26:30 -0700 (PDT) Date: Wed, 18 Jun 2025 13:26:22 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.50.0.rc2.696.g1fc2a0284f-goog Message-ID: <20250618132622.3730219-1-richardycc@google.com> Subject: [PATCH] zram: support asynchronous writeback From: Richard Chang To: Minchan Kim , Sergey Senozhatsky , Jens Axboe Cc: bgeffon@google.com, liumartin@google.com, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, Richard Chang Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" This commit introduces asynchronous writeback to zram, improving the idle writeback speed. Key changes include: * Replacing `submit_bio_wait()` with `submit_bio()` to enable non-blocking writeback operations. * Utilizing a dedicated kthread for post-writeback tasks, avoiding potential lock contention in interrupt context. * Refactoring writeback-related code into a separate file `zram_wb.c`, for better organization and maintainability. Signed-off-by: Richard Chang --- drivers/block/zram/Makefile | 1 + drivers/block/zram/zram_drv.c | 142 ++++++++-------------- drivers/block/zram/zram_drv.h | 37 ++++++ drivers/block/zram/zram_wb.c | 222 ++++++++++++++++++++++++++++++++++ drivers/block/zram/zram_wb.h | 41 +++++++ 5 files changed, 353 insertions(+), 90 deletions(-) create mode 100644 drivers/block/zram/zram_wb.c create mode 100644 drivers/block/zram/zram_wb.h diff --git a/drivers/block/zram/Makefile b/drivers/block/zram/Makefile index 0fdefd576691..31ee1ed34e17 100644 --- a/drivers/block/zram/Makefile +++ b/drivers/block/zram/Makefile @@ -8,5 +8,6 @@ zram-$(CONFIG_ZRAM_BACKEND_LZ4HC) +=3D backend_lz4hc.o zram-$(CONFIG_ZRAM_BACKEND_ZSTD) +=3D backend_zstd.o zram-$(CONFIG_ZRAM_BACKEND_DEFLATE) +=3D backend_deflate.o zram-$(CONFIG_ZRAM_BACKEND_842) +=3D backend_842.o +zram-$(CONFIG_ZRAM_WRITEBACK) +=3D zram_wb.o =20 obj-$(CONFIG_ZRAM) +=3D zram.o diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 54c57103715f..1cdebff13049 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -36,6 +36,7 @@ #include =20 #include "zram_drv.h" +#include "zram_wb.h" =20 static DEFINE_IDR(zram_index_idr); /* idr index must be protected */ @@ -56,7 +57,6 @@ static size_t huge_class_size; =20 static const struct block_device_operations zram_devops; =20 -static void zram_free_page(struct zram *zram, size_t index); static int zram_read_from_zspool(struct zram *zram, struct page *page, u32 index); =20 @@ -95,7 +95,7 @@ static __must_check bool zram_slot_trylock(struct zram *z= ram, u32 index) return false; } =20 -static void zram_slot_lock(struct zram *zram, u32 index) +void zram_slot_lock(struct zram *zram, u32 index) { unsigned long *lock =3D &zram->table[index].flags; =20 @@ -104,7 +104,7 @@ static void zram_slot_lock(struct zram *zram, u32 index) lock_acquired(slot_dep_map(zram, index), _RET_IP_); } =20 -static void zram_slot_unlock(struct zram *zram, u32 index) +void zram_slot_unlock(struct zram *zram, u32 index) { unsigned long *lock =3D &zram->table[index].flags; =20 @@ -127,19 +127,17 @@ static unsigned long zram_get_handle(struct zram *zra= m, u32 index) return zram->table[index].handle; } =20 -static void zram_set_handle(struct zram *zram, u32 index, unsigned long ha= ndle) +void zram_set_handle(struct zram *zram, u32 index, unsigned long handle) { zram->table[index].handle =3D handle; } =20 -static bool zram_test_flag(struct zram *zram, u32 index, - enum zram_pageflags flag) +bool zram_test_flag(struct zram *zram, u32 index, enum zram_pageflags flag) { return zram->table[index].flags & BIT(flag); } =20 -static void zram_set_flag(struct zram *zram, u32 index, - enum zram_pageflags flag) +void zram_set_flag(struct zram *zram, u32 index, enum zram_pageflags flag) { zram->table[index].flags |=3D BIT(flag); } @@ -233,22 +231,6 @@ static void zram_accessed(struct zram *zram, u32 index) } =20 #if defined CONFIG_ZRAM_WRITEBACK || defined CONFIG_ZRAM_MULTI_COMP -struct zram_pp_slot { - unsigned long index; - struct list_head entry; -}; - -/* - * A post-processing bucket is, essentially, a size class, this defines - * the range (in bytes) of pp-slots sizes in particular bucket. - */ -#define PP_BUCKET_SIZE_RANGE 64 -#define NUM_PP_BUCKETS ((PAGE_SIZE / PP_BUCKET_SIZE_RANGE) + 1) - -struct zram_pp_ctl { - struct list_head pp_buckets[NUM_PP_BUCKETS]; -}; - static struct zram_pp_ctl *init_pp_ctl(void) { struct zram_pp_ctl *ctl; @@ -258,15 +240,20 @@ static struct zram_pp_ctl *init_pp_ctl(void) if (!ctl) return NULL; =20 + init_completion(&ctl->all_done); + atomic_set(&ctl->num_pp_slots, 0); for (idx =3D 0; idx < NUM_PP_BUCKETS; idx++) INIT_LIST_HEAD(&ctl->pp_buckets[idx]); return ctl; } =20 -static void release_pp_slot(struct zram *zram, struct zram_pp_slot *pps) +static void remove_pp_slot_from_ctl(struct zram_pp_slot *pps) { list_del_init(&pps->entry); +} =20 +void free_pp_slot(struct zram *zram, struct zram_pp_slot *pps) +{ zram_slot_lock(zram, pps->index); zram_clear_flag(zram, pps->index, ZRAM_PP_SLOT); zram_slot_unlock(zram, pps->index); @@ -274,7 +261,13 @@ static void release_pp_slot(struct zram *zram, struct = zram_pp_slot *pps) kfree(pps); } =20 -static void release_pp_ctl(struct zram *zram, struct zram_pp_ctl *ctl) +static void release_pp_slot(struct zram *zram, struct zram_pp_slot *pps) +{ + remove_pp_slot_from_ctl(pps); + free_pp_slot(zram, pps); +} + +void release_pp_ctl(struct zram *zram, struct zram_pp_ctl *ctl) { u32 idx; =20 @@ -312,6 +305,7 @@ static bool place_pp_slot(struct zram *zram, struct zra= m_pp_ctl *ctl, list_add(&pps->entry, &ctl->pp_buckets[bid]); =20 zram_set_flag(zram, pps->index, ZRAM_PP_SLOT); + atomic_inc(&ctl->num_pp_slots); return true; } =20 @@ -713,7 +707,7 @@ static unsigned long alloc_block_bdev(struct zram *zram) return blk_idx; } =20 -static void free_block_bdev(struct zram *zram, unsigned long blk_idx) +void free_block_bdev(struct zram *zram, unsigned long blk_idx) { int was_set; =20 @@ -737,18 +731,18 @@ static void read_from_bdev_async(struct zram *zram, s= truct page *page, static int zram_writeback_slots(struct zram *zram, struct zram_pp_ctl *ctl) { unsigned long blk_idx =3D 0; - struct page *page =3D NULL; struct zram_pp_slot *pps; - struct bio_vec bio_vec; - struct bio bio; - int ret =3D 0, err; + int ret =3D 0; u32 index; + int nr_pps =3D atomic_read(&ctl->num_pp_slots); =20 - page =3D alloc_page(GFP_KERNEL); - if (!page) - return -ENOMEM; + if (!nr_pps) + return 0; =20 while ((pps =3D select_pp_slot(ctl))) { + struct zram_wb_request *req; + struct page *page; + spin_lock(&zram->wb_limit_lock); if (zram->wb_limit_enable && !zram->bd_wb_limit) { spin_unlock(&zram->wb_limit_lock); @@ -765,6 +759,13 @@ static int zram_writeback_slots(struct zram *zram, str= uct zram_pp_ctl *ctl) } } =20 + req =3D alloc_wb_request(zram, pps, ctl, blk_idx); + if (IS_ERR(req)) { + ret =3D PTR_ERR(req); + break; + } + page =3D bio_first_page_all(req->bio); + index =3D pps->index; zram_slot_lock(zram, index); /* @@ -779,63 +780,28 @@ static int zram_writeback_slots(struct zram *zram, st= ruct zram_pp_ctl *ctl) goto next; zram_slot_unlock(zram, index); =20 - bio_init(&bio, zram->bdev, &bio_vec, 1, - REQ_OP_WRITE | REQ_SYNC); - bio.bi_iter.bi_sector =3D blk_idx * (PAGE_SIZE >> 9); - __bio_add_page(&bio, page, PAGE_SIZE, 0); - - /* - * XXX: A single page IO would be inefficient for write - * but it would be not bad as starter. - */ - err =3D submit_bio_wait(&bio); - if (err) { - release_pp_slot(zram, pps); - /* - * BIO errors are not fatal, we continue and simply - * attempt to writeback the remaining objects (pages). - * At the same time we need to signal user-space that - * some writes (at least one, but also could be all of - * them) were not successful and we do so by returning - * the most recent BIO error. - */ - ret =3D err; - continue; - } - - atomic64_inc(&zram->stats.bd_writes); - zram_slot_lock(zram, index); - /* - * Same as above, we release slot lock during writeback so - * slot can change under us: slot_free() or slot_free() and - * reallocation (zram_write_page()). In both cases slot loses - * ZRAM_PP_SLOT flag. No concurrent post-processing can set - * ZRAM_PP_SLOT on such slots until current post-processing - * finishes. - */ - if (!zram_test_flag(zram, index, ZRAM_PP_SLOT)) - goto next; - - zram_free_page(zram, index); - zram_set_flag(zram, index, ZRAM_WB); - zram_set_handle(zram, index, blk_idx); + nr_pps--; + remove_pp_slot_from_ctl(pps); blk_idx =3D 0; - atomic64_inc(&zram->stats.pages_stored); - spin_lock(&zram->wb_limit_lock); - if (zram->wb_limit_enable && zram->bd_wb_limit > 0) - zram->bd_wb_limit -=3D 1UL << (PAGE_SHIFT - 12); - spin_unlock(&zram->wb_limit_lock); + submit_bio(req->bio); + continue; + next: zram_slot_unlock(zram, index); release_pp_slot(zram, pps); + free_wb_request(req); =20 cond_resched(); } =20 if (blk_idx) free_block_bdev(zram, blk_idx); - if (page) - __free_page(page); + + if (nr_pps && atomic_sub_and_test(nr_pps, &ctl->num_pp_slots)) + complete(&ctl->all_done); + + /* wait until all async bios completed */ + wait_for_completion(&ctl->all_done); =20 return ret; } @@ -1111,8 +1077,6 @@ static int read_from_bdev(struct zram *zram, struct p= age *page, { return -EIO; } - -static void free_block_bdev(struct zram *zram, unsigned long blk_idx) {}; #endif =20 #ifdef CONFIG_ZRAM_MEMORY_TRACKING @@ -1620,7 +1584,7 @@ static bool zram_meta_alloc(struct zram *zram, u64 di= sksize) return true; } =20 -static void zram_free_page(struct zram *zram, size_t index) +void zram_free_page(struct zram *zram, size_t index) { unsigned long handle; =20 @@ -2247,12 +2211,6 @@ static ssize_t recompress_store(struct device *dev, goto release_init_lock; } =20 - page =3D alloc_page(GFP_KERNEL); - if (!page) { - ret =3D -ENOMEM; - goto release_init_lock; - } - ctl =3D init_pp_ctl(); if (!ctl) { ret =3D -ENOMEM; @@ -2912,6 +2870,9 @@ static int __init zram_init(void) num_devices--; } =20 + if (setup_zram_writeback()) + goto out_error; + return 0; =20 out_error: @@ -2921,6 +2882,7 @@ static int __init zram_init(void) =20 static void __exit zram_exit(void) { + destroy_zram_writeback(); destroy_devices(); } =20 diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 6cee93f9c0d0..7d9081215668 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -139,4 +139,41 @@ struct zram { #endif atomic_t pp_in_progress; }; + +void zram_slot_lock(struct zram *zram, u32 index); +void zram_slot_unlock(struct zram *zram, u32 index); +void zram_set_handle(struct zram *zram, u32 index, unsigned long handle); +bool zram_test_flag(struct zram *zram, u32 index, enum zram_pageflags flag= ); +void zram_set_flag(struct zram *zram, u32 index, enum zram_pageflags flag); +void zram_free_page(struct zram *zram, size_t index); + +#if defined CONFIG_ZRAM_WRITEBACK || defined CONFIG_ZRAM_MULTI_COMP +struct zram_pp_slot { + unsigned long index; + struct list_head entry; +}; + +/* + * A post-processing bucket is, essentially, a size class, this defines + * the range (in bytes) of pp-slots sizes in particular bucket. + */ +#define PP_BUCKET_SIZE_RANGE 64 +#define NUM_PP_BUCKETS ((PAGE_SIZE / PP_BUCKET_SIZE_RANGE) + 1) + +struct zram_pp_ctl { + struct list_head pp_buckets[NUM_PP_BUCKETS]; + struct completion all_done; + atomic_t num_pp_slots; +}; + +void free_pp_slot(struct zram *zram, struct zram_pp_slot *pps); +void release_pp_ctl(struct zram *zram, struct zram_pp_ctl *ctl); +#endif + +#if IS_ENABLED(CONFIG_ZRAM_WRITEBACK) +void free_block_bdev(struct zram *zram, unsigned long blk_idx); +#else +inline void free_block_bdev(struct zram *zram, unsigned long blk_idx) {}; +#endif + #endif diff --git a/drivers/block/zram/zram_wb.c b/drivers/block/zram/zram_wb.c new file mode 100644 index 000000000000..59f93b22d2bf --- /dev/null +++ b/drivers/block/zram/zram_wb.c @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#define KMSG_COMPONENT "zram_wb" +#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt + +#include +#include +#include +#include +#include + +#include "zram_wb.h" + +static struct task_struct *wb_thread; +static DECLARE_WAIT_QUEUE_HEAD(wb_wq); +static struct zram_wb_request_list wb_req_list; + +static void complete_wb_request(struct zram_wb_request *req) +{ + struct zram *zram =3D req->zram; + struct zram_pp_slot *pps =3D req->pps; + struct zram_pp_ctl *ctl =3D req->ppctl; + unsigned long index =3D pps->index; + unsigned long blk_idx =3D req->blk_idx; + struct bio *bio =3D req->bio; + + if (bio->bi_status) + goto out_err; + + atomic64_inc(&zram->stats.bd_writes); + zram_slot_lock(zram, index); + + /* + * Same as above, we release slot lock during writeback so + * slot can change under us: slot_free() or slot_free() and + * reallocation (zram_write_page()). In both cases slot loses + * ZRAM_PP_SLOT flag. No concurrent post-processing can set + * ZRAM_PP_SLOT on such slots until current post-processing + * finishes. + */ + if (!zram_test_flag(zram, index, ZRAM_PP_SLOT)) { + zram_slot_unlock(zram, index); + goto out_err; + } + + zram_free_page(zram, index); + zram_set_flag(zram, index, ZRAM_WB); + zram_set_handle(zram, index, blk_idx); + atomic64_inc(&zram->stats.pages_stored); + spin_lock(&zram->wb_limit_lock); + if (zram->wb_limit_enable && zram->bd_wb_limit > 0) + zram->bd_wb_limit -=3D 1UL << (PAGE_SHIFT - 12); + spin_unlock(&zram->wb_limit_lock); + zram_slot_unlock(zram, index); + goto end; + +out_err: + free_block_bdev(zram, blk_idx); +end: + free_pp_slot(zram, pps); + free_wb_request(req); + + if (atomic_dec_and_test(&ctl->num_pp_slots)) + complete(&ctl->all_done); +} + +static void enqueue_wb_request(struct zram_wb_request_list *req_list, + struct zram_wb_request *req) +{ + /* + * The enqueue path comes from softirq context: + * blk_done_softirq -> bio_endio -> zram_writeback_end_io + * Use spin_lock_bh for locking. + */ + spin_lock_bh(&req_list->lock); + list_add_tail(&req->node, &req_list->head); + req_list->count++; + spin_unlock_bh(&req_list->lock); +} + +static struct zram_wb_request *dequeue_wb_request( + struct zram_wb_request_list *req_list) +{ + struct zram_wb_request *req =3D NULL; + + spin_lock_bh(&req_list->lock); + if (!list_empty(&req_list->head)) { + req =3D list_first_entry(&req_list->head, + struct zram_wb_request, + node); + list_del(&req->node); + req_list->count--; + } + spin_unlock_bh(&req_list->lock); + + return req; +} + +static void destroy_wb_request_list(struct zram_wb_request_list *req_list) +{ + struct zram_wb_request *req; + + while (!list_empty(&req_list->head)) { + req =3D dequeue_wb_request(req_list); + free_block_bdev(req->zram, req->blk_idx); + free_wb_request(req); + } +} + +static bool wb_ready_to_run(void) +{ + int count; + + spin_lock_bh(&wb_req_list.lock); + count =3D wb_req_list.count; + spin_unlock_bh(&wb_req_list.lock); + + return count > 0; +} + +static int wb_thread_func(void *data) +{ + set_freezable(); + + while (!kthread_should_stop()) { + wait_event_freezable(wb_wq, wb_ready_to_run()); + + while (1) { + struct zram_wb_request *req; + + req =3D dequeue_wb_request(&wb_req_list); + if (!req) + break; + complete_wb_request(req); + } + } + return 0; +} + +void zram_writeback_end_io(struct bio *bio) +{ + struct zram_wb_request *req =3D + (struct zram_wb_request *)bio->bi_private; + + enqueue_wb_request(&wb_req_list, req); + wake_up(&wb_wq); +} + +struct zram_wb_request *alloc_wb_request(struct zram *zram, + struct zram_pp_slot *pps, + struct zram_pp_ctl *ppctl, + unsigned long blk_idx) +{ + struct zram_wb_request *req; + struct page *page; + struct bio *bio; + int err =3D 0; + + page =3D alloc_page(GFP_NOIO | __GFP_NOWARN); + if (!page) + return ERR_PTR(-ENOMEM); + + bio =3D bio_alloc(zram->bdev, 1, REQ_OP_WRITE, GFP_NOIO | __GFP_NOWARN); + if (!bio) { + err =3D -ENOMEM; + goto out_free_page; + } + + req =3D kmalloc(sizeof(struct zram_wb_request), GFP_NOIO | __GFP_NOWARN); + if (!req) { + err =3D -ENOMEM; + goto out_free_bio; + } + req->zram =3D zram; + req->pps =3D pps; + req->ppctl =3D ppctl; + req->blk_idx =3D blk_idx; + req->bio =3D bio; + + bio->bi_iter.bi_sector =3D blk_idx * (PAGE_SIZE >> 9); + __bio_add_page(bio, page, PAGE_SIZE, 0); + bio->bi_private =3D req; + bio->bi_end_io =3D zram_writeback_end_io; + return req; + +out_free_bio: + bio_put(bio); +out_free_page: + __free_page(page); + return ERR_PTR(err); +} + +void free_wb_request(struct zram_wb_request *req) +{ + struct bio *bio =3D req->bio; + struct page *page =3D bio_first_page_all(bio); + + __free_page(page); + bio_put(bio); + kfree(req); +} + +int setup_zram_writeback(void) +{ + spin_lock_init(&wb_req_list.lock); + INIT_LIST_HEAD(&wb_req_list.head); + wb_req_list.count =3D 0; + + wb_thread =3D kthread_run(wb_thread_func, NULL, "zram_wb_thread"); + if (IS_ERR(wb_thread)) { + pr_err("Unable to create zram_wb_thread\n"); + return -1; + } + return 0; +} + +void destroy_zram_writeback(void) +{ + kthread_stop(wb_thread); + destroy_wb_request_list(&wb_req_list); +} + diff --git a/drivers/block/zram/zram_wb.h b/drivers/block/zram/zram_wb.h new file mode 100644 index 000000000000..e029b4de0de6 --- /dev/null +++ b/drivers/block/zram/zram_wb.h @@ -0,0 +1,41 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#ifndef _ZRAM_WRITEBACK_H_ +#define _ZRAM_WRITEBACK_H_ + +#include +#include "zram_drv.h" + +struct zram_wb_request; + +struct zram_wb_request { + struct zram *zram; + unsigned long blk_idx; + struct zram_pp_slot *pps; + struct zram_pp_ctl *ppctl; + struct bio *bio; + struct list_head node; +}; + +struct zram_wb_request_list { + struct list_head head; + int count; + spinlock_t lock; +}; + +#if IS_ENABLED(CONFIG_ZRAM_WRITEBACK) +void zram_writeback_end_io(struct bio *bio); +int setup_zram_writeback(void); +void destroy_zram_writeback(void); +struct zram_wb_request *alloc_wb_request(struct zram *zram, + struct zram_pp_slot *pps, + struct zram_pp_ctl *ppctl, + unsigned long blk_idx); +void free_wb_request(struct zram_wb_request *req); +#else +inline void zram_writeback_end_io(struct bio *bio) {} +inline int setup_zram_writeback(void) { return 0; } +inline void destroy_zram_writeback(void) {} +#endif + +#endif /* _ZRAM_WRITEBACK_H_ */ --=20 2.50.0.rc2.696.g1fc2a0284f-goog