Messages in this thread Patch in this message | | | Subject | Re: per-bdi-throttling: synchronous writepage doesn't work correctly | From | Peter Zijlstra <> | Date | Thu, 01 Nov 2007 20:55:37 +0100 |
| |
On Thu, 2007-11-01 at 20:19 +0100, Miklos Szeredi wrote: > > > > > > See the file "Locking" for more details. > > > > > > > > > The "should set PG_Writeback" bit threw me off I guess. > > > > Hmm, set_page_writeback() is also the one clearing the radix tree dirty > > tag. So if that is not called, we get in a bit of a mess, no? > > > > Which makes me think hostfs is buggy. > > Yes, looks like that sort of usage is not valid. But not clearing the > dirty tag won't cause any malfunction, it'll just waste some CPU when > looking for dirty pages to write back. This is probably why this > wasn't noticed earlier.
Documentation/filesystems/Locking is also quite clear on the need to call set_page_writeback() and end_page_writeback().
minimal fix for hostfs
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> ---
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c index 8966b05..b6c1e12 100644 --- a/fs/hostfs/hostfs_kern.c +++ b/fs/hostfs/hostfs_kern.c @@ -415,6 +415,7 @@ int hostfs_writepage(struct page *page, struct writeback_control *wbc) int end_index = inode->i_size >> PAGE_CACHE_SHIFT; int err; + set_page_writeback(page); if (page->index >= end_index) count = inode->i_size & (PAGE_CACHE_SIZE-1); @@ -438,6 +439,7 @@ int hostfs_writepage(struct page *page, struct writeback_control *wbc) kunmap(page); unlock_page(page); + end_page_writeback(page); return err; }
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |