mm/filemap.c: warn if stale pagecache is left after direct write

generic_file_direct_write() tries to invalidate pagecache after O_DIRECT
write.  Unlike to similar code in dio_complete() this silently ignores
error returned from invalidate_inode_pages2_range().

According to comment this code here because not all filesystems call
dio_complete() to do proper invalidation after O_DIRECT write.  Noticeable
example is a blkdev_direct_IO().

This patch calls dio_warn_stale_pagecache() if invalidation fails.

Link: http://lkml.kernel.org/r/157270038294.4812.2238891109785106069.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/filemap.c b/mm/filemap.c
index 189b8f3..dc3b78d 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3241,11 +3241,13 @@ generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
         * do not end up with dio_complete() being called, so let's not break
         * them by removing it completely.
         *
+        * Noticeable example is a blkdev_direct_IO().
+        *
         * Skip invalidation for async writes or if mapping has no pages.
         */
-       if (written > 0 && mapping->nrpages)
-               invalidate_inode_pages2_range(mapping,
-                                       pos >> PAGE_SHIFT, end);
+       if (written > 0 && mapping->nrpages &&
+           invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, end))
+               dio_warn_stale_pagecache(file);
 
        if (written > 0) {
                pos += written;