block: Fix page refcounts for unaligned buffers in __bio_release_pages()

Fix an incorrect number of pages being released for buffers that do not
start at the beginning of a page.

Fixes: 1b151e2435fc ("block: Remove special-casing of compound pages")
Cc: stable@vger.kernel.org
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Tested-by: Greg Edwards <gedwards@ddn.com>
Link: https://lore.kernel.org/r/86e592a9-98d4-4cff-a646-0c0084328356@cybernetics.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index 496867b51609f7a9dbca22f333fc66ab09fc249a..a8b691940027056948cf89b341fcb4b0c8b5f49d 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1153,7 +1153,7 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
 
        bio_for_each_folio_all(fi, bio) {
                struct page *page;
-               size_t done = 0;
+               size_t nr_pages;
 
                if (mark_dirty) {
                        folio_lock(fi.folio);
@@ -1161,10 +1161,11 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
                        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++);
-                       done += PAGE_SIZE;
-               } while (done < fi.length);
+               } while (--nr_pages != 0);
        }
 }
 EXPORT_SYMBOL_GPL(__bio_release_pages);