Re: [patch] call truncate_inode_pages in the DIO fallback to buffered I/O path

Jeff Moyer
2006-10-12T22:01:53Z

==> Regarding Re: [patch] call truncate_inode_pages in the DIO fallback to buffered I/O path; Andrew Morton <akpm@osdl.org> adds:

akpm> So I'd propose:

> diff -puN mm/filemap.c~direct-io-sync-and-invalidate-file-region-when-falling-back-to-buffered-write-fix mm/filemap.c
> --- a/mm/filemap.c~direct-io-sync-and-invalidate-file-region-when-falling-back-to-buffered-write-fix
> +++ a/mm/filemap.c
> @@ -2291,19 +2291,30 @@ __generic_file_aio_write_nolock(struct k
> written_buffered = generic_file_buffered_write(iocb, iov,
> nr_segs, pos, ppos, count,
> written);
> + /*
> + * If generic_file_buffered_write() retuned a synchronous error
> + * then we want to return the number of bytes which were
> + * direct-written, or the error code if that was zero. Note
> + * that this differs from normal direct-io semantics, which
> + * will return -EFOO even if some bytes were written.
> + */
> + if (written_buffered < 0) {
> + err = written_buffered;
> + goto out;
> + }

> /*
> * We need to ensure that the page cache pages are written to
> * disk and invalidated to preserve the expected O_DIRECT
> * semantics.
> */
> - endbyte = pos + written_buffered - 1;
> + endbyte = pos + written_buffered - written - 1;
> err = do_sync_file_range(file, pos, endbyte,
> SYNC_FILE_RANGE_WAIT_BEFORE|
> SYNC_FILE_RANGE_WRITE|
> SYNC_FILE_RANGE_WAIT_AFTER);
> if (err == 0) {
> - written += written_buffered;
> + written = written_buffered;
> invalidate_mapping_pages(mapping,
> pos >> PAGE_CACHE_SHIFT,
> endbyte >> PAGE_CACHE_SHIFT);
> _

This passes my tests and the Oracle tests that triggered the problem in the
first place. Thanks!

Acked-by: Jeff Moyer <jmoyer@redhat.com>