On Thu, Feb 09, 2012 at 01:30:27PM -0500, Chris Mason wrote: > On Thu, Feb 09, 2012 at 01:06:35PM -0500, Christoph Hellwig wrote: > > On Thu, Feb 09, 2012 at 04:02:24PM +0800, Wu Fengguang wrote: > > > On Thu, Feb 09, 2012 at 10:27:19AM +1100, Dave Chinner wrote: > > > > On Wed, Feb 08, 2012 at 07:01:44PM +0800, Wu Fengguang wrote: > > > > > Buffered write(2) is not directly tied to IO, so it's not suitable to > > > > > handle plug in generic_file_aio_write(). > > > > > > > > But generic_sync_write() does issue IO for O_SYNC writes, so unless > > > > there is plugging at a lower layer in the writeback code then it > > > > appears to me that plugging is still necessary (at least inside the > > > > sync branch).... > > > > > > Good catch! It looks that generic_write_sync() eventually calls into > > > vfs_fsync_range() which further calls ->fsync(). We may add plugging > > > around it: > > > > > > NAK, please keep the plugging down in the fs, or the libraries used but > > not common VFS code. > > Please, what Christoph said. At least for btrfs plugging here is wrong. OK, I get the point: the fs knows best when to unplug. Since any higher level plug nesting will turn such low level efforts into no-op, it's highly undesirable to do it in the high level. Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
