direct I/O fallback sync simplification

In the case of direct I/O falling back to buffered I/O we sync data
twice currently: once at the end of generic_file_buffered_write using
filemap_write_and_wait_range and once a little later in
__generic_file_aio_write using do_sync_mapping_range with all flags set.

The wait before write of the do_sync_mapping_range call does not make
any sense, so just keep the filemap_write_and_wait_range call and move
it to the right spot.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/mm/filemap.c b/mm/filemap.c
index 8b4d88f..96ac6b0 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2240,7 +2240,6 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                size_t count, ssize_t written)
 {
        struct file *file = iocb->ki_filp;
-       struct address_space *mapping = file->f_mapping;
        ssize_t status;
        struct iov_iter i;
 
@@ -2252,15 +2251,6 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
                *ppos = pos + status;
        }
        
-       /*
-        * If we get here for O_DIRECT writes then we must have fallen through
-        * to buffered writes (block instantiation inside i_size).  So we sync
-        * the file data here, to try to honour O_DIRECT expectations.
-        */
-       if (unlikely(file->f_flags & O_DIRECT) && written)
-               status = filemap_write_and_wait_range(mapping,
-                                       pos, pos + written - 1);
-
        return written ? written : status;
 }
 EXPORT_SYMBOL(generic_file_buffered_write);
@@ -2359,10 +2349,7 @@ ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
                 * semantics.
                 */
                endbyte = pos + written_buffered - written - 1;
-               err = do_sync_mapping_range(file->f_mapping, pos, endbyte,
-                                           SYNC_FILE_RANGE_WAIT_BEFORE|
-                                           SYNC_FILE_RANGE_WRITE|
-                                           SYNC_FILE_RANGE_WAIT_AFTER);
+               err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
                if (err == 0) {
                        written = written_buffered;
                        invalidate_mapping_pages(mapping,