linux-kernel - Re: [PATCH v8 07/10] block: Switch to pinning pages.

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Message-ID: <Y9AOYXpU1cRAHfQz@infradead.org>
Date:   Tue, 24 Jan 2023 08:59:13 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     David Howells <dhowells@...hat.com>
Cc:     Christoph Hellwig <hch@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Matthew Wilcox <willy@...radead.org>,
        Jens Axboe <axboe@...nel.dk>, Jan Kara <jack@...e.cz>,
        Jeff Layton <jlayton@...nel.org>,
        Logan Gunthorpe <logang@...tatee.com>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v8 07/10] block: Switch to pinning pages.

This is the incremental patch.  Doesn't do the FOLL_PIN to bool
conversion for the extra helper yet, and needs to be folded into the
original patches still.


diff --git a/block/bio.c b/block/bio.c
index 6dc54bf3ed27d4..bd8433f3644fd7 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1170,14 +1170,20 @@ bool bio_add_folio(struct bio *bio, struct folio *folio, size_t len,
 
 void __bio_release_pages(struct bio *bio, bool mark_dirty)
 {
-	unsigned int gup_flags = bio_to_gup_flags(bio);
+	bool pinned = bio_flagged(bio, BIO_PAGE_PINNED);
+	bool reffed = bio_flagged(bio, BIO_PAGE_REFFED);
 	struct bvec_iter_all iter_all;
 	struct bio_vec *bvec;
 
 	bio_for_each_segment_all(bvec, bio, iter_all) {
 		if (mark_dirty && !PageCompound(bvec->bv_page))
 			set_page_dirty_lock(bvec->bv_page);
-		page_put_unpin(bvec->bv_page, gup_flags);
+
+		if (pinned)
+			unpin_user_page(bvec->bv_page);
+		/* this can go away once direct-io.c is converted: */
+		else if (reffed)
+			put_page(bvec->bv_page);
 	}
 }
 EXPORT_SYMBOL_GPL(__bio_release_pages);
diff --git a/block/blk.h b/block/blk.h
index 294044d696e09f..a16d4425d2751c 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -430,27 +430,19 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
  */
 static inline void bio_set_cleanup_mode(struct bio *bio, struct iov_iter *iter)
 {
-	unsigned int cleanup_mode = iov_iter_extract_mode(iter);
-
-	if (cleanup_mode & FOLL_GET)
-		bio_set_flag(bio, BIO_PAGE_REFFED);
-	if (cleanup_mode & FOLL_PIN)
+	if (iov_iter_extract_mode(iter) & FOLL_PIN)
 		bio_set_flag(bio, BIO_PAGE_PINNED);
 }
 
-static inline unsigned int bio_to_gup_flags(struct bio *bio)
-{
-	return (bio_flagged(bio, BIO_PAGE_REFFED) ? FOLL_GET : 0) |
-		(bio_flagged(bio, BIO_PAGE_PINNED) ? FOLL_PIN : 0);
-}
-
 /*
  * Clean up a page appropriately, where the page may be pinned, may have a
  * ref taken on it or neither.
  */
 static inline void bio_release_page(struct bio *bio, struct page *page)
 {
-	page_put_unpin(page, bio_to_gup_flags(bio));
+	WARN_ON_ONCE(bio_flagged(bio, BIO_PAGE_REFFED));
+	if (bio_flagged(bio, BIO_PAGE_PINNED))
+		unpin_user_page(page);
 }
 
 struct request_queue *blk_alloc_queue(int node_id);