On Mon, 16 Oct 2006 13:38:19 -0700
Badari Pulavarty <[email protected]> wrote:
> >
> > So the answer is that -rc1-mm1 doesn't quite have the most recent
> > version of this patch. Grab the final patch at the end of this post
> > from Andrew:
> >
> > http://lkml.org/lkml/2006/10/11/234
> >
> > It fixes up a misunderstanding that came from
> > generic_file_buffered_write()'s habit of adding its 'written' input into
> > the amount of bytes it announces having written in its return value.
> >
> > From mm-commits it looks like -mm2 will have the full patch.
> >
>
> Hmm.. with that patch applied, I still have fsx failures.
> This time read() returning -EINVAL. Are there any other fixes
> missing in -mm ?
Probably. I need to get off butt and prepare rc2-mm1.
The below is the full patch against 2.6.19-rc2. Please test this version.
From: Jeff Moyer <[email protected]>
When direct-io falls back to buffered write, it will just leave the dirty data
floating about in pagecache, pending regular writeback.
But normal direct-io semantics are that IO is synchronous, and that it leaves
no pagecache behind.
So change the fallback-to-buffered-write code to sync the file region and to
then strip away the pagecache, just as a regular direct-io write would do.
Acked-by: Jeff Moyer <[email protected]>
Cc: Zach Brown <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
mm/filemap.c | 51 +++++++++++++++++++++++++++++++++++++++++++------
1 files changed, 45 insertions(+), 6 deletions(-)
diff -puN mm/filemap.c~direct-io-sync-and-invalidate-file-region-when-falling-back-to-buffered-write mm/filemap.c
--- a/mm/filemap.c~direct-io-sync-and-invalidate-file-region-when-falling-back-to-buffered-write
+++ a/mm/filemap.c
@@ -2222,7 +2222,7 @@ __generic_file_aio_write_nolock(struct k
unsigned long nr_segs, loff_t *ppos)
{
struct file *file = iocb->ki_filp;
- const struct address_space * mapping = file->f_mapping;
+ struct address_space * mapping = file->f_mapping;
size_t ocount; /* original count */
size_t count; /* after file limit checks */
struct inode *inode = mapping->host;
@@ -2275,8 +2275,11 @@ __generic_file_aio_write_nolock(struct k
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
if (unlikely(file->f_flags & O_DIRECT)) {
- written = generic_file_direct_write(iocb, iov,
- &nr_segs, pos, ppos, count, ocount);
+ loff_t endbyte;
+ ssize_t written_buffered;
+
+ written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
+ ppos, count, ocount);
if (written < 0 || written == count)
goto out;
/*
@@ -2285,10 +2288,46 @@ __generic_file_aio_write_nolock(struct k
*/
pos += written;
count -= written;
- }
+ 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;
+ }
- written = generic_file_buffered_write(iocb, iov, nr_segs,
- pos, ppos, count, written);
+ /*
+ * 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 - 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;
+ invalidate_mapping_pages(mapping,
+ pos >> PAGE_CACHE_SHIFT,
+ endbyte >> PAGE_CACHE_SHIFT);
+ } else {
+ /*
+ * We don't know how much we wrote, so just return
+ * the number of bytes which were direct-written
+ */
+ }
+ } else {
+ written = generic_file_buffered_write(iocb, iov, nr_segs,
+ pos, ppos, count, written);
+ }
out:
current->backing_dev_info = NULL;
return written ? written : err;
_
-
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