On Sun 15-11-09 19:46:41, Theodore Tso wrote: > On Tue, Oct 27, 2009 at 01:48:49PM +0100, Jan Kara wrote: > > + /* > > + * Transactions that contain inode's metadata needed to complete > > + * fsync and fdatasync, respectively. > > + */ > > + atomic_t i_sync_tid; > > + atomic_t i_datasync_tid; > > Why do we need an atomic_t here at all? It's not clear it's > necessary. What specific race are you worried about? Well, i_[data]sync_tid are set and read from several places which aren't currently synchronized against each other and I din't want to introduce any synchronization. So atomic_t seemed like a clean way of making clear that loads / stores from those fields are atomic, regardless of architecture, memory alignment or whatever insanity that might make us see just half overwritten field. On all archs where this means just plain stores / loads (such as x86), there's no performance hit since the operations are implemented as such. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
