Messages in this thread | | | Subject | Re: [PATCH] aio: propogate post-EIOCBQUEUED errors to completion event | From | Trond Myklebust <> | Date | Tue, 20 Feb 2007 19:05:19 -0500 |
| |
On Tue, 2007-02-20 at 10:40 -0800, Zach Brown wrote: > >> There are some strange O_DIRECT corner cases in here such that the > >> 'last > >> writer' may actually be a 'last reader' and winning can mean have > >> a copy > >> of the page in page cache older than the copy on disk. > > > > As long as it is marked dirty so that it eventually gets synced to > > disk, > > it shouldn't matter. > > No, Chris is pointing out that an an O_DIRECT write can leave clean > read pages in the page cache. > > All it takes is giving a source buffer for the write which is an mmap > ()ed apeture of the region that is being written to. If you get the > offsets right you can get the get_user_pages() down in fs/direct-io.c > will populate the page cache before the actual O_DIRECT write gets to > it.
With invalidate_inode_pages2()? That is supposed to wait until the page lock is taken -> read is done. It then calls unmap_mapping_range() which will remove the offending page from any existing mappings. Sure an application could get stale data, but if it is reading while an O_DIRECT write is proceeding, then it gets what it deserves.
Trond
- 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/
| |