On Wed, May 30, 2012 at 11:57:43PM +0000, Nicholas A. Bellinger wrote: > From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> > > This patch converts fd_execute_cmd() code to drop O_SYNC usage > (the original default) in favor of always preforming an implict > SCSI forced unit access (FUA) operation using vfs_fsync_range() > based on LBA + SectorCount after each completed FILEIO backend write. > > This conversion was inspired by Linus's thoughts on O_SYNC usage in > the thread: http://www.spinics.net/lists/linux-fsdevel/msg55681.html > > "O_SYNC is the absolutely anti-thesis of that kind of "multiple levels > of overlapping IO". Because it requires that the IO is _done_ by the > time you start more, which is against the whole point." > > This patch also drops the now unnecessary fd_buffered_io= token usage > at createvirtdev time. Tested with lio-core code using fio writeverify > to local tcm_loop + FILEIO <-> scsi_debug backed LUNs. If you look at the implementation O_SYNC really just means an implicit vfs_fsync_range after each write, thus I can't see how this patch makes any difference. For target use with WCE=0 semantics you could at least switch to O_DSYNC, though. -- 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
