block: Add BIO_PAGE_PINNED and associated infrastructure

Add BIO_PAGE_PINNED to indicate that the pages in a bio are pinned
(FOLL_PIN) and that the pin will need removing.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Jan Kara <jack@suse.cz>
cc: Matthew Wilcox <willy@infradead.org>
cc: Logan Gunthorpe <logang@deltatee.com>
cc: linux-block@vger.kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230522205744.2825689-5-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index 8516ade..17bd01e 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1169,7 +1169,7 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
        bio_for_each_segment_all(bvec, bio, iter_all) {
                if (mark_dirty && !PageCompound(bvec->bv_page))
                        set_page_dirty_lock(bvec->bv_page);
-               put_page(bvec->bv_page);
+               bio_release_page(bio, bvec->bv_page);
        }
 }
 EXPORT_SYMBOL_GPL(__bio_release_pages);
@@ -1489,8 +1489,8 @@ void bio_set_pages_dirty(struct bio *bio)
  * the BIO and re-dirty the pages in process context.
  *
  * It is expected that bio_check_pages_dirty() will wholly own the BIO from
- * here on.  It will run one put_page() against each page and will run one
- * bio_put() against the BIO.
+ * here on.  It will unpin each page and will run one bio_put() against the
+ * BIO.
  */
 
 static void bio_dirty_fn(struct work_struct *work);

diff --git a/block/blk.h b/block/blk.h
index 9f171b8..7ad7cb6 100644 (file)
--- a/block/blk.h
+++ b/block/blk.h
@@ -420,6 +420,18 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
                struct page *page, unsigned int len, unsigned int offset,
                unsigned int max_sectors, bool *same_page);
 
+/*
+ * 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)
+{
+       if (bio_flagged(bio, BIO_PAGE_PINNED))
+               unpin_user_page(page);
+       else if (bio_flagged(bio, BIO_PAGE_REFFED))
+               put_page(page);
+}
+
 struct request_queue *blk_alloc_queue(int node_id);
 
 int disk_scan_partitions(struct gendisk *disk, fmode_t mode);

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 0922729..8588bcf 100644 (file)
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -488,7 +488,8 @@ void zero_fill_bio(struct bio *bio);
 
 static inline void bio_release_pages(struct bio *bio, bool mark_dirty)
 {
-       if (bio_flagged(bio, BIO_PAGE_REFFED))
+       if (bio_flagged(bio, BIO_PAGE_REFFED) ||
+           bio_flagged(bio, BIO_PAGE_PINNED))
                __bio_release_pages(bio, mark_dirty);
 }
 

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index dfd2c2c..8ef209e 100644 (file)
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -323,6 +323,7 @@ struct bio {
  * bio flags
  */
 enum {
+       BIO_PAGE_PINNED,        /* Unpin pages in bio_release_pages() */
        BIO_PAGE_REFFED,        /* put pages in bio_release_pages() */
        BIO_CLONED,             /* doesn't own data */
        BIO_BOUNCED,            /* bio is a bounce bio */