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From:   cgel.zte@gmail.com
To:     axboe@kernel.dk, viro@zeniv.linux.org.uk, hannes@cmpxchg.org
Cc:     linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org,
        Yang Yang <yang.yang29@zte.com.cn>,
        Ran Xiaokai <ran.xiaokai@zte.com.cn>
Subject: [PATCH] block/psi: make PSI annotations of submit_bio only work for file pages
Date:   Wed, 16 Mar 2022 06:39:28 +0000
Message-Id: <20220316063927.2128383-1-yang.yang29@zte.com.cn>
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From: Yang Yang <yang.yang29@zte.com.cn>

psi tracks the time spent on submitting the IO of refaulting file pages
and anonymous pages[1]. But after we tracks refaulting anonymous pages
in swap_readpage[2][3], there is no need to track refaulting anonymous
pages in submit_bio.

So this patch can reduce redundant calling of psi_memstall_enter. And
make it easier to track refaulting file pages and anonymous pages
separately.

[1] commit b8e24a9300b0 ("block: annotate refault stalls from IO submission")
[2] commit 937790699be9 ("mm/page_io.c: annotate refault stalls from swap_readpage")
[3] commit 2b413a1a728f ("mm: page_io: fix psi memory pressure error on cold swapins")

Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
---
 block/bio.c               | 9 +++++----
 block/blk-core.c          | 2 +-
 fs/direct-io.c            | 2 +-
 include/linux/blk_types.h | 2 +-
 4 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 3c57b3ba727d..54b60be4f3b0 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1035,8 +1035,9 @@ void __bio_add_page(struct bio *bio, struct page *page,
 	bio->bi_iter.bi_size += len;
 	bio->bi_vcnt++;
 
-	if (!bio_flagged(bio, BIO_WORKINGSET) && unlikely(PageWorkingset(page)))
-		bio_set_flag(bio, BIO_WORKINGSET);
+	if (!bio_flagged(bio, BIO_WORKINGSET_FILE) &&
+	    unlikely(PageWorkingset(page)) && !PageSwapBacked(page))
+		bio_set_flag(bio, BIO_WORKINGSET_FILE);
 }
 EXPORT_SYMBOL_GPL(__bio_add_page);
 
@@ -1254,7 +1255,7 @@ static int __bio_iov_append_get_pages(struct bio *bio, struct iov_iter *iter)
  * is returned only if 0 pages could be pinned.
  *
  * It's intended for direct IO, so doesn't do PSI tracking, the caller is
- * responsible for setting BIO_WORKINGSET if necessary.
+ * responsible for setting BIO_WORKINGSET_FILE if necessary.
  */
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 {
@@ -1274,7 +1275,7 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 	} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
 
 	/* don't account direct I/O as memory stall */
-	bio_clear_flag(bio, BIO_WORKINGSET);
+	bio_clear_flag(bio, BIO_WORKINGSET_FILE);
 	return bio->bi_vcnt ? 0 : ret;
 }
 EXPORT_SYMBOL_GPL(bio_iov_iter_get_pages);
diff --git a/block/blk-core.c b/block/blk-core.c
index ddac62aebc55..9a955323734b 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -918,7 +918,7 @@ void submit_bio(struct bio *bio)
 	 * part of overall IO time.
 	 */
 	if (unlikely(bio_op(bio) == REQ_OP_READ &&
-	    bio_flagged(bio, BIO_WORKINGSET))) {
+	    bio_flagged(bio, BIO_WORKINGSET_FILE))) {
 		unsigned long pflags;
 
 		psi_memstall_enter(&pflags);
diff --git a/fs/direct-io.c b/fs/direct-io.c
index aef06e607b40..7cdec50fb27b 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -420,7 +420,7 @@ static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
 
 	bio->bi_private = dio;
 	/* don't account direct I/O as memory stall */
-	bio_clear_flag(bio, BIO_WORKINGSET);
+	bio_clear_flag(bio, BIO_WORKINGSET_FILE);
 
 	spin_lock_irqsave(&dio->bio_lock, flags);
 	dio->refcount++;
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 0c7a9a1f06c8..a1aaba4767e9 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -314,7 +314,7 @@ enum {
 	BIO_NO_PAGE_REF,	/* don't put release vec pages */
 	BIO_CLONED,		/* doesn't own data */
 	BIO_BOUNCED,		/* bio is a bounce bio */
-	BIO_WORKINGSET,		/* contains userspace workingset pages */
+	BIO_WORKINGSET_FILE,	/* contains userspace workingset file pages */
 	BIO_QUIET,		/* Make BIO Quiet */
 	BIO_CHAIN,		/* chained bio, ->bi_remaining in effect */
 	BIO_REFFED,		/* bio has elevated ->bi_cnt */
-- 
2.25.1