From: Matthew Wilcox (Oracle) willy@infradead.org
commit 39f985c8f667c80a3d1eb19d31138032fa36b09e upstream.
Cachefiles was relying on wait_page_key and wait_bit_key being the same layout, which is fragile. Now that wait_page_key is exposed in the pagemap.h header, we can remove that fragility
A comment on the need to maintain structure layout equivalence was added by Linus[1] and that is no longer applicable.
Fixes: 62906027091f ("mm: add PageWaiters indicating tasks are waiting for a page bit") Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: David Howells dhowells@redhat.com Tested-by: kafs-testing@auristor.com cc: linux-cachefs@redhat.com cc: linux-mm@kvack.org Link: https://lore.kernel.org/r/20210320054104.1300774-2-willy@infradead.org/ Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... [1] Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/cachefiles/rdwr.c | 7 +++---- include/linux/pagemap.h | 1 - 2 files changed, 3 insertions(+), 5 deletions(-)
--- a/fs/cachefiles/rdwr.c +++ b/fs/cachefiles/rdwr.c @@ -24,17 +24,16 @@ static int cachefiles_read_waiter(wait_q container_of(wait, struct cachefiles_one_read, monitor); struct cachefiles_object *object; struct fscache_retrieval *op = monitor->op; - struct wait_bit_key *key = _key; + struct wait_page_key *key = _key; struct page *page = wait->private;
ASSERT(key);
_enter("{%lu},%u,%d,{%p,%u}", monitor->netfs_page->index, mode, sync, - key->flags, key->bit_nr); + key->page, key->bit_nr);
- if (key->flags != &page->flags || - key->bit_nr != PG_locked) + if (key->page != page || key->bit_nr != PG_locked) return 0;
_debug("--- monitor %p %lx ---", page, page->flags); --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -559,7 +559,6 @@ static inline pgoff_t linear_page_index( return pgoff; }
-/* This has the same layout as wait_bit_key - see fs/cachefiles/rdwr.c */ struct wait_page_key { struct page *page; int bit_nr;