On Fri, Aug 08, 2014 at 12:04:40PM -0400, Chris Mason wrote: > > xfs is using truncate_pagecache_range to invalidate the page cache > during DIO writes. The other filesystems are calling > invalidate_inode_pages2_range > > truncate_pagecache_range is meant to be used when we are freeing the > underlying data structs from disk, so it will zero any partial ranges > in the page. This means a DIO write can zero out part of the page cache > page, and it is possible the page will stay in cache. > > This one is an RFC because it is untested and because I don't understand > how XFS is dealing with pages the truncate was unable to clear away. > I'm not able to actually trigger zeros by mixing DIO writes with > buffered reads. > > Signed-off-by: Chris Mason <clm@xxxxxx> > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 8d25d98..c30c112 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -638,7 +638,10 @@ xfs_file_dio_aio_write( > pos, -1); > if (ret) > goto out; > - truncate_pagecache_range(VFS_I(ip), pos, -1); > + > + /* what do we do if we can't invalidate the pages? */ > + invalidate_inode_pages2_range(VFS_I(ip)->i_mapping, > + pos >> PAGE_CACHE_SHIFT, -1); I don't think it can on XFS. We're holding the XFS_IOLOCK_EXCL, so no other syscall based IO can dirty pages, all the pages are clean, try_to_free_buffers() will never fail, no-one can run a truncate operation concurently, and so on. The only thing that could cause an issue is a racing mmap page fault dirtying the page. But if you are mixing mmap+direct IO on the same file, you lost a long time ago so that's nothing new at all. So, I'd just do: ret = invalidate_inode_pages2_range(VFS_I(ip)->i_mapping, pos >> PAGE_CACHE_SHIFT, -1); WARN_ON_ONCE(ret); ret = 0; That way we'll find out if it does ever fail, and if it does we can take it from there. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
