On 9:53 01/07, Christoph Hellwig wrote: > On Mon, Jun 29, 2020 at 02:23:49PM -0500, Goldwyn Rodrigues wrote: > > From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> > > > > For direct I/O, add the flag IOMAP_DIO_RWF_NO_STALE_PAGECACHE to indicate > > that if the page invalidation fails, return back control to the > > filesystem so it may fallback to buffered mode. > > > > Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx> > > I'd like to start a discussion of this shouldn't really be the > default behavior. If we have page cache that can't be invalidated it > actually makes a whole lot of sense to not do direct I/O, avoid the > warnings, etc. > > Adding all the relevant lists. Since no one responded so far, let me see if I can stir the cauldron :) What error should be returned in case of such an error? I think the userspace process must be immediately informed if it in unable to invalidate the page cache and complete the direct I/O. Currently, the iomap code treats this as a writeback error and continues with the direct I/O and the userspace process comes to know only during file closure. If such a change is incorporated, are the current userspace applications prepared for it? -- Goldwyn
