+ zram-directly-call-zram_read_page-in-writeback_store.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: zram: directly call zram_read_page in writeback_store
has been added to the -mm mm-unstable branch.  Its filename is
     zram-directly-call-zram_read_page-in-writeback_store.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-directly-call-zram_read_page-in-writeback_store.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Christoph Hellwig <hch@lst.de>
Subject: zram: directly call zram_read_page in writeback_store
Date: Thu, 6 Apr 2023 16:40:55 +0200

writeback_store always reads a full page, so just call zram_read_page
directly and bypass the boune buffer handling.

Link: https://lkml.kernel.org/r/20230406144102.149231-10-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/zram/zram_drv.c |   14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

--- a/drivers/block/zram/zram_drv.c~zram-directly-call-zram_read_page-in-writeback_store
+++ a/drivers/block/zram/zram_drv.c
@@ -54,9 +54,8 @@ static size_t huge_class_size;
 static const struct block_device_operations zram_devops;
 
 static void zram_free_page(struct zram *zram, size_t index);
-static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec,
-				u32 index, int offset, struct bio *bio);
-
+static int zram_read_page(struct zram *zram, struct page *page, u32 index,
+			  struct bio *bio, bool partial_io);
 
 static int zram_slot_trylock(struct zram *zram, u32 index)
 {
@@ -671,10 +670,6 @@ static ssize_t writeback_store(struct de
 	}
 
 	for (; nr_pages != 0; index++, nr_pages--) {
-		struct bio_vec bvec;
-
-		bvec_set_page(&bvec, page, PAGE_SIZE, 0);
-
 		spin_lock(&zram->wb_limit_lock);
 		if (zram->wb_limit_enable && !zram->bd_wb_limit) {
 			spin_unlock(&zram->wb_limit_lock);
@@ -718,7 +713,7 @@ static ssize_t writeback_store(struct de
 		/* Need for hugepage writeback racing */
 		zram_set_flag(zram, index, ZRAM_IDLE);
 		zram_slot_unlock(zram, index);
-		if (zram_bvec_read(zram, &bvec, index, 0, NULL)) {
+		if (zram_read_page(zram, page, index, NULL, false)) {
 			zram_slot_lock(zram, index);
 			zram_clear_flag(zram, index, ZRAM_UNDER_WB);
 			zram_clear_flag(zram, index, ZRAM_IDLE);
@@ -729,9 +724,8 @@ static ssize_t writeback_store(struct de
 		bio_init(&bio, zram->bdev, &bio_vec, 1,
 			 REQ_OP_WRITE | REQ_SYNC);
 		bio.bi_iter.bi_sector = blk_idx * (PAGE_SIZE >> 9);
+		bio_add_page(&bio, page, PAGE_SIZE, 0);
 
-		bio_add_page(&bio, bvec.bv_page, bvec.bv_len,
-				bvec.bv_offset);
 		/*
 		 * XXX: A single page IO would be inefficient for write
 		 * but it would be not bad as starter.
_

Patches currently in -mm which might be from hch@lst.de are

zram-remove-valid_io_request.patch
zram-make-zram_bio_discard-more-self-contained.patch
zram-simplify-bvec-iteration-in-__zram_make_request.patch
zram-move-discard-handling-to-zram_submit_bio.patch
zram-return-early-on-error-in-zram_bvec_rw.patch
zram-refactor-highlevel-read-and-write-handling.patch
zram-dont-use-highmem-for-the-bounce-buffer-in-zram_bvec_readwrite.patch
zram-rename-__zram_bvec_read-to-zram_read_page.patch
zram-directly-call-zram_read_page-in-writeback_store.patch
zram-refactor-zram_bdev_read.patch
zram-dont-pass-a-bvec-to-__zram_bvec_write.patch
zram-refactor-zram_bdev_write.patch
zram-pass-a-page-to-read_from_bdev.patch
zram-dont-return-errors-from-read_from_bdev_async.patch
zram-fix-synchronous-reads.patch
zram-return-errors-from-read_from_bdev_sync.patch