afs: Use wait_on_page_writeback_killable

Open-coding this function meant it missed out on the recent bugfix
for waiters being woken by a delayed wake event from a previous
instantiation of the page[1].

[DH: Changed the patch to use vmf->page rather than variable page which
 doesn't exist yet upstream]

Fixes: 1cf7a1518aef ("afs: Implement shared-writeable mmap")
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-afs@lists.infradead.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20210320054104.1300774-4-willy@infradead.org
Link: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c2407cf7d22d0c0d94cf20342b3b8f06f1d904e7

diff --git a/fs/afs/write.c b/fs/afs/write.c
index c9195fc67fd8fc41dbe5614b04e3cd9a5f0e42dd..eb737ed63afb6041f26207171b95960e5ec6e7a9 100644 (file)
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -851,8 +851,7 @@ vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
        fscache_wait_on_page_write(vnode->cache, vmf->page);
 #endif
 
-       if (PageWriteback(vmf->page) &&
-           wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
+       if (wait_on_page_writeback_killable(vmf->page))
                return VM_FAULT_RETRY;
 
        if (lock_page_killable(vmf->page) < 0)