[PATCH v7 4/4] block: unpin user pages belonging to a folio at once

[Kundan Kumar <kundan.kumar@xxxxxxxxxxx>]

Add a new function bio_release_folio() and use it to put refs by npages
count.

Signed-off-by: Kundan Kumar <kundan.kumar@xxxxxxxxxxx>
---
 block/bio.c        |  7 +------
 block/blk.h        |  7 +++++++
 include/linux/mm.h |  1 +
 mm/gup.c           | 13 +++++++++++++
 4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 32c9c6d80384..0d923140006e 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1205,20 +1205,15 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
 	struct folio_iter fi;
 
 	bio_for_each_folio_all(fi, bio) {
-		struct page *page;
 		size_t nr_pages;
-
 		if (mark_dirty) {
 			folio_lock(fi.folio);
 			folio_mark_dirty(fi.folio);
 			folio_unlock(fi.folio);
 		}
-		page = folio_page(fi.folio, fi.offset / PAGE_SIZE);
 		nr_pages = (fi.offset + fi.length - 1) / PAGE_SIZE -
 			   fi.offset / PAGE_SIZE + 1;
-		do {
-			bio_release_page(bio, page++);
-		} while (--nr_pages != 0);
+		bio_release_folio(bio, fi.folio, nr_pages);
 	}
 }
 EXPORT_SYMBOL_GPL(__bio_release_pages);
diff --git a/block/blk.h b/block/blk.h
index 0c8857fe4079..18520b05c6ce 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -548,6 +548,13 @@ static inline void bio_release_page(struct bio *bio, struct page *page)
 		unpin_user_page(page);
 }
 
+static inline void bio_release_folio(struct bio *bio, struct folio *folio,
+				     unsigned long npages)
+{
+	if (bio_flagged(bio, BIO_PAGE_PINNED))
+		unpin_user_folio(folio, npages);
+}
+
 struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id);
 
 int disk_scan_partitions(struct gendisk *disk, blk_mode_t mode);
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9849dfda44d4..b902c6c39e2b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1618,6 +1618,7 @@ void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,
 void unpin_user_page_range_dirty_lock(struct page *page, unsigned long npages,
 				      bool make_dirty);
 void unpin_user_pages(struct page **pages, unsigned long npages);
+void unpin_user_folio(struct folio *folio, unsigned long npages);
 
 static inline bool is_cow_mapping(vm_flags_t flags)
 {
diff --git a/mm/gup.c b/mm/gup.c
index ca0f5cedce9b..bc96efa43d1b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -488,6 +488,19 @@ void unpin_user_pages(struct page **pages, unsigned long npages)
 }
 EXPORT_SYMBOL(unpin_user_pages);
 
+/**
+ * unpin_user_folio() - release pages of a folio
+ * @folio:  pointer to folio to be released
+ * @npages: number of pages of same folio
+ *
+ * Release npages of the folio
+ */
+void unpin_user_folio(struct folio *folio, unsigned long npages)
+{
+	gup_put_folio(folio, npages, FOLL_PIN);
+}
+EXPORT_SYMBOL(unpin_user_folio);
+
 /*
  * Set the MMF_HAS_PINNED if not set yet; after set it'll be there for the mm's
  * lifecycle.  Avoid setting the bit unless necessary, or it might cause write
-- 
2.25.1