On Wed, Dec 17, 2014 at 12:24:37AM -0800, Christoph Hellwig wrote: > On Wed, Dec 17, 2014 at 08:20:21AM +0000, Al Viro wrote: > > Where the hell would those other references come from? We open the damn > > thing in sys_swapon(), never put it into descriptor tables, etc. and > > the only reason why we use filp_close() instead of fput() is that we > > would miss ->flush() otherwise. > > > > Said that, why not simply *open* it with O_DIRECT to start with and be done > > with that? It's not as if those guys came preopened by caller - swapon(2) > > gets a pathname and does opening itself. > > Oops, should have dug deeper into the code. For some reason I assumed > the fd is passed in from userspace. > > The suggestion from Al is much better, given that we never do normal > I/O on the swapfile, just the bmap + direct bio submission which I hope > could go away in favor of the direct I/O variant in the long run. See my previous message. If we use O_DIRECT on the original open, then filesystems that implement bmap but not direct_IO will no longer work. These are the ones that I found in my tree: adfs befs bfs ecryptfs efs freevxfs hpfs isofs minix ntfs omfs qnx4 qnx6 sysv ufs Several of these are read only, and I can't imagine that anyone is using a swapfile on any of the rest, but if someone is, this would be a regression, wouldn't it? -- Omar -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>